217 results
Search Results
2. Study on paper-structured catalyst for direct internal reforming SOFC fueled by the mixture of CH4 and CO2.
- Author
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Shiratori, Yusuke, Ogura, Teppei, Nakajima, Hironori, Sakamoto, Mio, Takahashi, Yutaro, Wakita, Yuto, Kitaoka, Takuya, and Sasaki, Kazunari
- Subjects
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CHEMICAL structure , *CATALYTIC reforming , *SOLID oxide fuel cells , *GAS mixtures , *CARBON dioxide , *CATALYST supports , *METHANE , *ENERGY conversion , *BIOGAS - Abstract
Abstract: Inorganic fiber network including YSZ fiber which acts as catalyst support was created by the simple paper-making process, and novel Ni-loaded paper-structured catalysts (PSCs) with excellent catalytic activity for the dry reforming of methane were designed and developed. The PSCs exhibited high fuel conversion comparable to the conventional powdered catalysts with less than one-tenth catalyst weights. The significant advantages of the PSCs are their high mechanical flexibility and material workability. So far, a functionally-graded catalytic reaction field which leads to uniform temperature distribution during biogas reforming resulting in stable operation of planar SOFC was successfully developed by the PSC array based on the kinetic simulation model built in this research. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
3. Mn doped CoFe layered double hydroxides lead to d-d orbital repulsion toward advanced electrocatalysts for oxygen evolution reaction.
- Author
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Yang, Yibin, Gao, Di, Ou, Yingqing, Yang, Yang, Xiao, Peng, and Zhang, Yunhuai
- Subjects
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OXYGEN evolution reactions , *LAYERED double hydroxides , *HYDROGEN evolution reactions , *ELECTROCATALYSTS , *CARBON dioxide , *CARBON paper - Abstract
Currently, developing highly active and low-cost electrocatalytic materials for oxygen evolution reaction (OER) is an enormously grand challenge. Herein, we developed a novel and highly active Mn doped Co 2 Fe layer double hydroxide (LDH) electrocatalyst for OER. We discovered that these electrocatalytic materials can be directly grown on carbon papers to construct high-specific-surface-area electrode, which shows the lowest overpotential of 266 mV at 10 mA cm−2. Furthermore, after introducing Mn element, DFT + U calculation found that the ∗OOH of Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH could draw more electrons than Co 2 Fe LDH due to the electronegativity differences between Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH and Fe-site on Co 2 Fe LDH, which is reason that the energy level of Fe 3d (e g) was obviously downshifted by d-d repulsion of Mn 3d and Fe 3d in the neighboring sites of Co 2 Fe 0.67 Mn 0.33 LDH after doped Mn element, which leads to reduce charge-transfer energy from O 2p to Fe 3d (e g) to promote oxygen evolution processes for OER. Meanwhile, the band gap is also decreased after doped Mn element in Co 2 Fe LDH due to the downshifted e g orbital energy of Fe 3d. This study gives a general avenue to design and developing efficiently active LDH electrocatalysts for OER in the future. • Both bimetallic CoFe LDH and Mn doped CoFe LDHs directly grown on carbon paper are successfully synthesized. • The Co 2 Fe 0.67 Mn 0.33 LDH@NFs exhibits a small overpotential of 236 mV at 10 mA cm−1 for OER. • DFT + U studies reveal that the observed superb OER activity could be attributed to d-d repulsion of Mn 3d and Fe 3d. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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4. Modeling & optimization of renewable hydrogen production from biomass via anaerobic digestion & dry reformation
- Author
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Udaya Bhaskar Reddy Ragula, Rishi Kaashyap Balaji, and Krishna Prasad Rajan
- Subjects
Hydrogen ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,01 natural sciences ,Methane ,0104 chemical sciences ,Catalysis ,Steam reforming ,chemistry.chemical_compound ,Anaerobic digestion ,Fuel Technology ,chemistry ,Biogas ,Carbon dioxide ,Environmental science ,0210 nano-technology ,Hydrogen production - Abstract
There is a growing interest in the usage of hydrogen as an environmentally cleaner form of energy for end users. However, hydrogen does not occur naturally and needs to be produced through energy intensive processes, such as steam reformation. In order to be truly renewable, hydrogen must be produced through processes that do not lead to direct or indirect carbon dioxide emissions. Dry reformation of methane is a route that consumes carbon dioxide to produce hydrogen. This work describes the production of hydrogen from biomass via anaerobic digestion of waste biomass and dry reformation of biogas. This process consumes carbon dioxide instead of releasing it and uses only renewable feed materials for hydrogen production. An end-to-end simulation of this process is developed primarily using Aspen HYSYS® and consists of steady state models for anaerobic digestion of biomass, dry reformation of biogas in a fixed-bed catalytic reactor containing Ni–Co/Al2O3 catalyst, and a custom-model for hydrogen separation using a hollow fibre membrane separator. A mixture-process variable design is used to simultaneously optimize feed composition and process conditions for the process. It is identified that if biogas containing 52 mol% methane, 38 mol% carbon dioxide, and 10 mol% water (or steam) is used for hydrogen production by dry reformation at a temperature of 837.5 °C and a pressure of 101.3 kPa; optimal values of 89.9% methane conversion, 99.99% carbon dioxide conversion and hydrogen selectivity 1.21 can be obtained.
- Published
- 2020
5. An experimental approach to produce hydrogen and methane from food waste using catalyst
- Author
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Chinmay Deheri and S. K. Acharya
- Subjects
Hydrogen ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,01 natural sciences ,Methane ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Food waste ,Fuel Technology ,Biogas ,Calcium peroxide ,Carbon dioxide ,0210 nano-technology ,Cow dung - Abstract
Anaerobic co-digestion of food waste, cow dung, and sludge solution is experimented in the presence of calcium peroxide (CaO2) as the catalyst to produce hydrogen and methane as a source of renewable energy. The substrate to inoculum ratios (v/v) of 1:1(S1), 1:2(S2), 1:3(S3), 1:4(S4) and 1:5(S5) are investigated in separate fermentative and methanogenic reactors. The result from the fermentative reactors indicate maximum hydrogen concentration of 26.34% with cumulative yield of 114.1 mL/g total solid (TS) in S3 compared to the other samples. Methanogenic reaction shows the highest methane concentration of 54.13% in S3. The highest daily (average) and cumulative biogas yield of 5.36 mL/g TS and 201.9 mL/g TS respectively are identified in S3. A maximum carbon dioxide concentration of 63.11% is found in S1. Overall, the substrate to inoculum ratio of 1:3 is spotted to be optimal for effective hydrogen and methane production during the anaerobic co-digestion process.
- Published
- 2020
6. Modulating composition and electronic structure enhance the catalytic performance of Co2MO4 (M=Fe, Ni, Cu) for NaBH4 hydrolysis.
- Author
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Wu, Longxiang, Yang, Mao, Liu, Yonghui, Wu, Yucheng, Huang, Duohui, Juxiang Shao, and Wang, Xiaolian
- Subjects
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ELECTRONIC structure , *CATALYTIC hydrolysis , *HYDROLYSIS , *VALENCE bands , *DENSITY functional theory , *CARBON dioxide - Abstract
The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. [Display omitted] • Flower-like Co 2 FeO 4 showed the best catalytic performance. • The "D-band center" and "valence -band center" of Co 2 MO 4 were studied. • Composition and electronic control improve the catalytic performance of Co 2 MO 4. • The adsorption configuration of H 2 O on the Co 2 MO 4 (311) surface was studied. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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7. Techno-economic assessment of a chemical looping reforming combined cycle plant with iron and tungsten based oxygen carriers
- Author
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Mohammed N. Khan and Tariq Shamim
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Materials science ,Hydrogen ,Combined cycle ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,Tungsten ,010402 general chemistry ,01 natural sciences ,Oxygen ,law.invention ,chemistry.chemical_compound ,law ,Natural gas ,Renewable Energy, Sustainability and the Environment ,business.industry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,0104 chemical sciences ,Fuel Technology ,chemistry ,Carbon dioxide ,0210 nano-technology ,business ,Electrical efficiency ,Chemical looping combustion - Abstract
Chemical looping reforming (CLR) is an efficient technology that transforms hydrocarbons into hydrogen (H2) and carbon dioxide (CO2) with the use of an oxygen carrier. The three-reactor CLR (TRCLR) uses natural gas as fuel similar to a conventional steam-methane reforming (SMR) process. In the current study, two of the most suitable oxygen carriers with base metals iron (Fe) and tungsten (W) are investigated. The model of the CLR unit integrated with a combined cycle power plant is developed using Aspen Plus. The results show that the W-based TRCLR plants are 4 %-points more efficient in terms of H2 production efficiency. In terms of electrical efficiency, the Fe-based TRCLR plant produces excess power at an efficiency of 1.6% whereas the W-based plant requires 3% of extra power from the grid. As a result, the Fe-based plant is 2.6 %-points more efficient than the W-based plant in terms of global efficiency. The costs of H2 production for the Fe and W-based plants are estimated to be $1.66/kg and $16.92/kg, respectively. Compared to the SMR process, the cost of H2 production from the Fe-based TRCLR plant is about 31% lower.
- Published
- 2019
8. A well to pump life cycle environmental impact assessment of some hydrogen production routes
- Author
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Ibrahim Dincer and Osamah Siddiqui
- Subjects
Electrolysis of water ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,01 natural sciences ,0104 chemical sciences ,Steam reforming ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Carbon dioxide ,Environmental science ,Coal gasification ,Nitrogen dioxide ,Methanol ,0210 nano-technology ,Life-cycle assessment ,Hydrogen production - Abstract
In the present study, a comparative well to pump life cycle assessment is conducted on the hydrogen production routes of water electrolysis, biomass gasification, coal gasification, steam methane reforming, hydrogen production from ethanol and methanol. The CML 2001 impact assessment methodology is employed for assessment and comparison. Comparatively higher life cycle Carbon dioxide and Sulphur oxide emissions of 27.3 kg/kg H2 and 50.0 g/kg H2 respectively are determined for the water electrolysis hydrogen production route via U.S. electricity mix. In addition, the life cycle global warming potential of this route (28.6 kg CO2eq/kg H2) is found to be comparatively higher than other routes followed by coal gasification (23.7 kg CO2eq/kg H2). However, the ethanol based hydrogen production route is estimated to have comparatively higher life cycle emissions of nitrogen dioxide (19.6 g/kg H2) and volatile organic compounds (10.3 g/kg H2). Moreover, this route is determined to have a comparatively higher photochemical ozone creation potential of 0.0045 kg-etheneeq/kg H2 as well as eutrophication potential of 0.0043 kg PO4eq/kg H2. The results of this study are comparatively discussed to signify the importance of life cycle assessment in comparing the environmental sustainability of hydrogen production routes.
- Published
- 2019
9. Carbon dioxide hydrogenation for sustainable energy storage.
- Author
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Boretti, Alberto
- Subjects
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CLEAN energy , *CARBON sequestration , *GASOLINE , *ENERGY storage , *CARBON dioxide , *GREEN diesel fuels , *METHYL ether , *METHANOL as fuel - Abstract
This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
10. Effect of hydroxy and hydrogen gas addition on diesel engine fuelled with microalgae biodiesel
- Author
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Erinç Uludamar
- Subjects
Biodiesel ,Materials science ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,020209 energy ,05 social sciences ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,Raw material ,Condensed Matter Physics ,Diesel engine ,Pulp and paper industry ,law.invention ,Ignition system ,chemistry.chemical_compound ,Ultra-low-sulfur diesel ,Fuel Technology ,chemistry ,law ,0502 economics and business ,Carbon dioxide ,0202 electrical engineering, electronic engineering, information engineering ,050207 economics ,Carbon monoxide - Abstract
Owing to high growth rate, being non-edible, and environmental friendliness; microalgae is a promising third generation biodiesel raw material. In this study, hydrogen and hydroxy gas aspirated compression ignition engine which was fuelled with microalgae biodiesel and low sulphur diesel fuel blend were investigated in order to evaluate their combined effect. The results showed that the brake power and torque output of the test engine decreased with microalgae biodiesel usage. Moreover, microalgae biodiesel addition results in lower carbon monoxide and nitrogen oxides emissions, and higher carbon dioxide. The introduction of hydrogen and hydroxy gas compensated the decrement of torque and power output and increment of carbon dioxide emission. The study enlightened that usage of microalgae biodiesel with hydrogen and hydroxy gas addition is a very promising combination from the environmental viewpoint.
- Published
- 2018
11. Hydrogen-rich syngas produced from the co-pyrolysis of municipal solid waste and wheat straw
- Author
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Zhao Jun, Wang Shuzhong, Wu Zhiqiang, Meng Haiyu, and Chen Lin
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Materials science ,Municipal solid waste ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Biomass ,02 engineering and technology ,Straw ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Carbon dioxide ,0202 electrical engineering, electronic engineering, information engineering ,Heat of combustion ,0210 nano-technology ,Carbon ,Pyrolysis ,Syngas - Abstract
The co-thermochemical conversion of Municipal Solid Waste (MSW) and biomass is a new environmental technology and can produce hydrogen-rich syngas. This study investigated the co-pyrolysis of MSW and wheat straw, using a drop-tube furnace experiment. Using a temperature range of 500 °C–1000 °C, the study assessed pyrolysis gas yield, product distribution, gas low heating value, and carbon conversion of co-pyrolysis MSW with different amounts of wheat straw. Adding wheat straw only slightly increases the gas yield and carbon conversion, but improved the carbon monoxide and carbon dioxide in the syngas. At an experimental temperature below 700 °C, adding wheat straw promoted the cracking reaction of hydrocarbon gas, generated by the pyrolysis of MSW. At a temperature of 600 °C, adding 25% wheat straw improved carbon conversion in the blended sample. This study provides a basis for the application of MSW and WS thermo-chemical conversion.
- Published
- 2017
12. Two-stage thermophilic fermentation and mesophilic methanogenic process for biohythane production from palm oil mill effluent with methanogenic effluent recirculation for pH control
- Author
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Wantanasak Suksong, Mathavee Thipmunee, Chonticha Mamimin, Sompong O-Thong, Poonsuk Prasertsan, and Kanathip Promnuan
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Hydrogen ,Renewable Energy, Sustainability and the Environment ,Chemistry ,020209 energy ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Pulp and paper industry ,Methane ,chemistry.chemical_compound ,Fuel Technology ,Pome ,Carbon dioxide ,0202 electrical engineering, electronic engineering, information engineering ,Fermentation ,0210 nano-technology ,Effluent ,Hydrogen production ,Mesophile - Abstract
Two-stage thermophilic fermentation and mesophilic methanogenic process with methanogenic effluent recirculation to hydrogen reactor for biohythane production from palm oil mill effluent (POME) was investigated. Maximum hydrogen (4.1 L H2/L-POME) and methane production (16.6 L CH4/L-POME) from POME in batch tests were achieved at 30% recirculation rate of methanogenic effluent. Continuous hydrogen production of without and with recirculation phase was 2.2 and 3.8 L H2/L-POME, respectively. Continuous methane production of without and with recirculation phase was 12.2 and 14 L CH4/L-POME, respectively. Both reactor effluents were effective to keep at optimal pH with 2 times increasing in hydrogen production. The hydrogen and methane yield were 135 mL H2/gVS and 414 mL CH4/gVS, respectively. Biohythane gas composition was composed 13.3% of hydrogen, 54.4% of methane and 32.2% carbon dioxide. Two-stage process with methanogenic effluent recirculation flavored Thermoanaerobacterium sp. in the hydrogen reactor and efficiently for energy recovery from POME.
- Published
- 2016
13. A systematic review of CO2 injection for enhanced oil recovery and carbon storage in shale reservoirs.
- Author
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Wang, Lu, Zhang, Yifan, Zou, Rui, Zou, Run, Huang, Liang, Liu, Yisheng, Meng, Zhan, Wang, Zhilin, and Lei, Hao
- Subjects
- *
ENHANCED oil recovery , *SHALE , *SHALE oils , *PROPERTIES of fluids , *CARBON dioxide - Abstract
Global shale oil is abundant in geological reserves, but there are widespread problems of difficult exploitation and unsatisfactory oil recovery. CO 2 injection in shale reservoirs can achieve effective exploitation of shale reservoirs and alleviate the current energy shortage. In this paper, investigations on shale oil in recent years were summarized and analyzed. Firstly, the reservoir characteristics and fluid properties of several shale reservoirs and their effects on CO 2 -enhanced oil recovery (CO 2 -EOR) were analyzed, including porosity, permeability, mineral composition, pore structure, geomechanical characteristics and organic matter properties of shale reservoirs, as well as the density, viscosity, gas-oil ratio and composition of shale oil. Subsequently, multiple mechanisms of CO 2 -EOR in shale reservoirs were revealed, including swelling, diffusion, viscosity reduction, extraction, miscibility, and competitive adsorption. The effects of temperature, pressure, CO 2 injection amount, oil composition and reservoir heterogeneity on different mechanisms were analyzed. The effects of nanopore confinement and CO 2 injection on the fluid phase were also analyzed. Then, the CO 2 storage forms of structural space, bound space, dissolution, and mineralization were introduced. And the effects of temperature, pressure, reservoir heterogeneity and formation water salinity on various forms of CO 2 storage were summarized. Furthermore, the research methods of CO 2 injection technique through molecular simulation, physical simulation, mathematical model, and reservoir numerical simulation were introduced. Finally, the reasonable prospect of CO 2 injection technique for shale oil reservoirs was proposed based on the current technical problems. The purpose of this paper is to provide a theoretical basis for EOR and carbon geological storage of shale reservoirs by using the CO 2 injection technique. [Display omitted] • Reservoir and fluid properties of major shale oil reservoirs were summarized. • EOR mechanisms of CO2 injection in shale reservoirs were reviewed systematically. • Research methods of CO2 injection techniques in shale reservoirs were introduced. • Future perspectives of CO 2 injection techniques in shale reservoirs were analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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14. Fe–Ni composite oxygen carrier for chemical looping gasification with diverse fuels to produce syngas.
- Author
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Zhang, Kun, Han, Xiaotong, Zhang, Chi, Wang, Yunfei, Wang, Siqiong, Li, Weida, and Zhang, Qiumin
- Subjects
- *
COAL gasification , *SOL-gel processes , *SYNTHESIS gas , *CARBON dioxide , *CHAR , *OXYGEN carriers , *BIOMASS gasification - Abstract
Coal-based chemical looping gasification (CCLG) has been proposed as an emergent type of coal gasification technology that produces high-quality syngas by using lattice oxygen from oxygen carrier instead of molecular oxygen. In this paper, the Fe–Ni composite oxygen carrier was synthetized using sol-gel method and the gasification performance of the prepared sample was analyzed by a fixed-bed reactor. The results indicated that the Fe–Ni composite oxygen carrier presented a high carbon conversion of fuel and syngas selectivity during the CCLG process. Additionally, the cycle stability test showed that the carbon conversion of fuel and syngas selectivity did not change significantly with the increase of cyclic frequency. To further study the influence of volatiles released from coal on the gasification performance of oxygen carrier, the interactions between the oxygen carrier samples and char obtained at different pyrolysis temperatures were investigated by a fixed-bed reactor and TG-MS, respectively. The results suggested that the gas products (H 2 , CO, CO 2 and CH 4) yields of char-oxygen carrier were significantly lower than those of coal-oxygen carrier. Besides, the pyrolysis temperature for preparing char had a great effect on the carbon conversion of fuel and syngas selectivity due to the distinction of volatiles released from solid fuel. • Efficient Fe–Ni composite oxygen carrier was crafted via sol-gel method. • Fe–Ni composite oxygen carrier showed good performance with desirable reactivity and cyclic stability. • Interaction between oxygen carrier and volatiles released from coal was investigated. • Char gasification was demonstrated to be the rate determining step during the CCLG process. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
15. Overview of the latest progress and prospects in the catalytic hydrogenation of carbon dioxide (CO2) to methanol in membrane reactors.
- Author
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Mohammed, Mustapha Grema, Hashim, N. Awanis, Daud, Wan Mohd Ashri Wan, Hartley, Unalome Wetwatana, Aroua, Mohamed Kheireddine, and Wohlrab, Sebastian
- Subjects
- *
MEMBRANE reactors , *CATALYTIC hydrogenation , *CARBON dioxide , *SUSTAINABILITY , *METHYL ether , *CATALYST structure - Abstract
Rising levels of carbon dioxide (CO 2) emissions due to human activities exert a substantial adverse effect on the environment. The conversion of CO 2 into methanol (CH 3 OH) through hydrogenation is a promising way to utilize this greenhouse gas, thus maintaining carbon in the cycle. In terms of sustainability, methanol is of particular interest because of its dual utilization potential as a fuel or base material to produce different chemicals. The versatility of the latter allows it to be used directly as a precursor to produce numerous compounds, including dimethyl ether (DME), olefins, formaldehydes, and hydrocarbon fuels. This paper first reviews the latest developments in catalyst design, focusing on the relationship between catalyst structure and performance. In addition, recent advances in understanding the reaction mechanisms, optimizing catalyst architectures, innovating membrane reactors, and reaction conditions have been discussed. This summarizes the strategies for increasing the efficiency of sustainable methanol production with the help of membranes. This study provides an outlook for future research in this field. [Display omitted] • Developing efficient hydrogen conversion is essential for addressing climate change. • Technological improvements in the synthesis of water selective zeolite membranes. • Latest developments in CO 2 hydrogenation using Cu-based catalysts. • Adapting zeolite membranes in catalytic membrane reactors to increase methanol yield. • Challenges and perspectives of CO 2 hydrogenation in the presence of a membrane. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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16. Effects of H2 blended ratio and N2/CO2 dilution fraction on the deflagration shock wave of H2NG in slender closed pipelines.
- Author
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Liu, Qiqi, Liu, Luoqian, Liu, Zhenyi, Peng, Shiyao, Liu, Chuang, Zhang, Hanwen, Liu, Changqi, Li, Pengliang, and Fan, Tao
- Subjects
- *
SHOCK waves , *NATURAL gas laws , *DILUTION , *THEORY of wave motion , *CARBON dioxide , *NATURAL gas - Abstract
To reveal the deflagration hazard and propagation law of hydrogen-enriched natural gas (H 2 NG) in closed spaces, this paper studied the deflagration characteristic parameters under different H 2 blended ratio (λ) and inert gas dilution fraction (X dilution) in slender closed pipelines with steel circular hole obstacles. The results indicate that the positive feedback mechanism's sustained effect, failure, and re-action leads to a "three-zone" distribution of H 2 NG explosion overpressure along the pipeline, namely the acceleration, attenuation, and rebound zones. The maximum explosion overpressure (P max), maximum pressure rise rate ((dP/dt) max), and peak shock wave propagation velocity (V p) all increase with the increase of λ. The rise of λ has the most significant enhancement effect on (dP/dt) max , while the enhancement effect on V p is the smallest. This is because the main reasons affecting their increase are different. P max , (dP/dt) max , and V p exhibit exponential decay with increased N 2 and CO 2. However, CO 2 has a more significant inhibitory effect on the H 2 NG deflagration process. When X CO2 = 25% and X CO2 = 30%, the deflagration process of H 2 NG with λ = 20% and λ = 80% can be inhibited entirely, respectively, which has important guiding significance for the safe application of H 2 NG. • The evolution law of deflagration shock waves in slender closed pipelines by H 2 NG was researched. • Effects of H 2 blended ratio and N 2 /CO 2 dilution fraction on H 2 NG deflagration characteristics were revealed. • The effects of N 2 /CO 2 dilution fraction on the P max , (dP/dt) max , and V p were predicted by an exponential model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Machine learning analysis of catalytic CO2 methanation.
- Author
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Yılmaz, Beyza, Oral, Burcu, and Yıldırım, Ramazan
- Subjects
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MACHINE learning , *METHANATION , *STANDARD deviations , *RANDOM forest algorithms , *CARBON dioxide , *DESCRIPTOR systems , *BIOMASS conversion - Abstract
In this work, a detailed dataset containing 4051 data points gathered from 527 distinct experiments in 100 published articles for catalytic CO 2 methanation was analyzed using machine learning methods. A pre-analysis of the database was performed using simple descriptive statistics while a random forest (RF) model was developed to predict CO 2 conversion as the function of 23 descriptors including catalyst properties, preparation methods, and reaction conditions. Boruta analysis was also performed to identify the significant variables. The random forest model was found to be quite successful in predicting CO 2 conversion with the training and testing root mean square error (RMSE) of 6.4 and 12.7 respectively; R2 was 0.97 for training while it was 0.85 for testing. The success of the model was also verified by computing CO 2 conversion profiles for individual experiments in test data and comparing them with those reported in the related papers. [Display omitted] • Catalytic CO 2 methanation was studied using machine learning. • Dataset contained 4051 data points from 100 published paper. • Simple descriptive statistics and random forest (RF) were used as tools. • RF successfully predicted CO 2 conversion profiles for the test cases. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. Air gasification of dried sewage sludge in a two-stage gasifier. Part 3: Application of olivine as a bed material and nickel coated distributor for the production of a clean hydrogen-rich producer gas
- Author
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Tae-Young Mun, Joo-Sik Kim, and Min-Hawn Cho
- Subjects
Materials science ,Wood gas generator ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy Engineering and Power Technology ,Tar ,chemistry.chemical_element ,Producer gas ,Condensed Matter Physics ,Pulp and paper industry ,complex mixtures ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Carbon dioxide ,medicine ,Coal ,business ,Sludge ,Activated carbon ,medicine.drug - Abstract
Air gasification of dried sewage sludge (DSS) was performed with olivine as the bed material and coal-based activated carbon as the tar-cracking additive in a two-stage gasifier to produce a hydrogen-rich producer gas with low tar content. Additionally, to investigate the possible regeneration of coal-based activated carbon, two different activating agents (carbon dioxide and steam) were applied. Finally, to reduce ammonia and tar contents, the performance of a Ni-coated distributor was examined. In the experiments, gasification at a steam to fuel ratio (STF) of 1.11 achieved a tar removal efficiency of 98% and a maximum hydrogen content of 34 vol.%. Furthermore, the activated carbon used for the gasification was less deactivated, compared to those used in the experiments without any reforming agent. When a Ni-coated distributor was applied, the ammonia content in the producer gas was significantly reduced to 11 ppm.
- Published
- 2014
19. Hydrogen production by biomass gasification in supercritical water: A parametric study
- Author
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Liejin Guo, Ximin Zhang, Qiuhui Yan, Xiaohong Hao, Youjun Lu, and C.M. Ji
- Subjects
Biomass to liquid ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,Biomass ,chemistry.chemical_element ,Condensed Matter Physics ,Pulp and paper industry ,Supercritical fluid ,Methane ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Carbon dioxide ,Water content ,Hydrogen production - Abstract
Hydrogen production by biomass gasification in supercritical water is a promising technology for utilizing high moisture content biomass, but reactor plugging is a critical problem when feedstocks with high biomass content are gasified. The objective of this paper is to prevent the plugging problem by studying the effects of the various parameters on biomass gasification in supercritical water. These parameters include pressure, temperature, residence time, reactor geometrical configuration, reactor types, heating rate, reactor wall properties, biomass types, biomass particle size, catalysts and solution concentration. Biomass model compounds (glucose, cellulose) and real biomass are used in this work. All the biomasses have been successfully gasified and the product gas is composed of hydrogen, carbon dioxide, methane, carbon monoxide and a small amount of ethane and ethylene. The results show that the gas yield of biomass gasification in supercritical water is sensitive to some of the parameters and the ways of reducing reactor plugging are obtained.
- Published
- 2006
20. Direct formation of dendritic Ag catalyst on a gas diffusion layer for electrochemical CO2 reduction to CO and H2.
- Author
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Ham, Yu Seok, Kim, Myung Jun, Lim, Taeho, Kim, Dong-Kwon, Kim, Soo-Kil, and Kim, Jae Jeong
- Subjects
- *
SILVER catalysts , *ELECTROCHEMICAL analysis , *CARBON dioxide , *CARBON paper , *ELECTROPLATING , *POLYETHYLENE glycol - Abstract
Dendritic Ag (a CO 2 -to-CO reduction catalyst) has been synthesized on carbon paper (CP) using pulse electrodeposition to fabricate a gas diffusion electrode. A combination of sonication and pulse deposition facilitated mass transfer of Ag ions to the CP, enlarging the catalyst active surface area without significantly changing the Ag crystalline structure. The current density of CO 2 reduction was proportional to the surface area of dendritic Ag. Further improvements in performance were achieved by adding polyethylene glycol to the CO 2 reduction cell catholyte that removed the CO gas bubbles produced at the electrode surface. The fabrication methods presented herein suggest an effective gas diffusion electrode for application in the membrane-electrode-assembly-type single cell for electrochemical CO 2 reduction. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
21. Towards chemical equilibrium in thermochemical water splitting. Part 2: Re-oxidation.
- Author
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de la Calle, Alberto, Ermanoski, Ivan, Miller, James E., and Stechel, Ellen B.
- Subjects
- *
CHEMICAL equilibrium , *CERIUM oxides , *CARBON dioxide , *HYDROLOGIC cycle , *NOBLE gases , *REMANUFACTURING , *OXIDATION - Abstract
Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step thermochemical water splitting cycles, which dissociate water into hydrogen (H 2) and oxygen (O 2) via sequential thermal reduction and re-oxidation processes. Building on the thermal reduction analysis presented in Part 1, this paper zeroes in on the re-oxidation reaction within the optimal reactor framework – the counter-current reactor. It elucidates the equilibrium pathway, delineating the progression of chemical equilibrium at each incremental stage of re-oxidation. Using ceria (CeO 2) as a model redox-active metal oxide, the investigation analyzes the influence of operational parameters on the re-oxidation reaction. Findings reveal the theoretical feasibility of maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving a total extent of reduction of 0.038 and a hydrogen conversion yield of 32%. While near adiabatic operation is also achievable, practicality is constrained by a maximum total extent of reduction of 6.5·10−3. The study also explores the economic implications of thermochemical water splitting, particularly focusing on the steam-to-hydrogen output ratio. It highlights the severe economic hurdles associated with hydrogen yields below approximately 1%. Furthermore, the investigation reveals that the addition of inert gas to the re-oxidation step offers no significant advantages. Concluding the analysis, a comparative assessment exposes negligible differences in outcomes when substituting carbon dioxide (CO 2) for water (H 2 O) as the oxidant in low-temperature scenarios (800 °C). This comprehensive study not only advances the understanding of re-oxidation dynamics in thermochemical water splitting but also informs practical and economic considerations crucial for the advancement of this technology. • Reversible/equilibrium re-oxidation pathway defined for water splitting cycles. • Reversible quasi-constant temperature and quasi-adiabatic re-oxidation is feasible. • Limited impact of gas purity on re-oxidation at fixed flow/minimum temperature. • Inert gas addition offers no thermodynamic advantage in re-oxidation. • Low re-oxidation temperatures expand the solution space for high cycle efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
22. Effects of H2/CO ratio and CO2 dilution on the explosion behavior and flame evolution of syngas/air mixtures.
- Author
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Su, Bin, Dong, Haowei, Luo, Zhenmin, Deng, Jun, Liao, Pengxiang, Cheng, Fangming, Wang, Tao, Liu, Litao, and Liu, Lu
- Subjects
- *
SYNTHESIS gas , *DILUTION , *FLAME stability , *FLAME , *CARBON dioxide , *EXPLOSIONS - Abstract
Syngas, which is used as both a fuel and a raw material, presents numerous safety risks during its utilization. In this paper, the effects of H 2 /CO ratio (R = 0%, 30%, 50%, 70% and 100%) and CO 2 dilution ([CO 2 ] = 0%–20%) on the explosion behaviors of syngas/air mixtures with different equivalence ratios (φ = 0.8, 1.0, 1.6, and 2.5) are examined via experiments and numerical calculations. The results show that the peaks of explosion pressure and OH* spectral intensity are significantly influenced by the H 2 percentage in the syngas. The introduction of CO 2 notably decreases these parameters in oxygen-rich and severe oxygen-poor states. Additionally, the flame propagation speed noticeably increases with increasing H 2 proportion in the syngas. The influence of CO 2 on the buoyancy instability of the spherical flame of syngas is considered negligible when compared to that of other combustible gases, such as CH 4. Nevertheless, the presence of CO 2 decreases the density ratio between the unburned gas and burned gas and increases the flame thickness of syngas/air mixtures. This trend reduces the cellular instability of the spherical flame, particularly in severe oxygen-poor states. Notably, there is a definite correlation between the formation of cellular flames and the rise rate of explosion pressure. The cellular structure on the flame surface becomes more pronounced when the rise rate of explosion pressure increases. Conversely, it develops later or is noticeably inhibited. Furthermore, the main reaction pathways are H 2 → ∙OH → H 2 O 2 → H 2 O and H 2 → ∙OH → CO → CO 2 during the syngas explosion process. ∙OH is critical in the entire chain reaction because it promotes the conversion of H 2 to H 2 O and acts as a vital connection between the reactants H 2 and CO in the explosion process. • The P max and I max were investigated with H 2 addition and CO 2 dilution. • The cellular instability of the spherical flame was analyzed. • The interaction of flame development and explosion pressure was revealed. • The main reaction pathways during the syngas explosion process were examined. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. Life cycle assessments use in hydrogen-related policies: The case for a harmonized methodology addressing multifunctionality.
- Author
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Arrigoni, Alessandro, Hurtig, Oliver, Buffi, Marco, Eynard, Umberto, Andreasi Bassi, Susanna, Scarlat, Nicolae, and Dolci, Francesco
- Subjects
- *
PRODUCT life cycle assessment , *GREENHOUSE gases , *INCENTIVE (Psychology) , *CARBON dioxide , *GREENHOUSE gas mitigation - Abstract
Legislation regulating the sustainability requirements for hydrogen technologies relies more and more on life cycle assessments (LCAs). Due to different scopes and development processes, different pieces of EU legislation refer to different LCA methodologies, with differences in the way multifunctional processes (i.e., co-productions, recycling, and energy recovery) are treated. These inconsistencies arise because incentive mechanisms are not standardized across sectors, even though the end product, hydrogen, remains the same. The goal of this paper is to compare the life-cycle greenhouse gas (GHG) emissions of hydrogen from four production pathways depending on the multifunctional approach prescribed by the different EU policies (e.g., using substitution or allocation). The study reveals a large variation in the LCA results. For instance, the life-cycle GHG emissions of hydrogen co-produced with methanol is found to vary from 1 kg CO 2 -equivalent/kg H 2 (when mass allocation is considered) to 11 kg CO 2 -equivalent/kg H 2 (when economic allocation is used). These inconsistencies could affect the market (e.g., hydrogen from a certain pathway could be considered sustainable or unsustainable depending on the approach) and the environment (e.g., pathways that do not lead to a global emission reduction could be promoted). To mitigate these potential negative effects, we urge for harmonized and strict guidelines to assess the life-cycle GHG emissions of hydrogen technologies in an EU policy context. Harmonization should cover international policies too, to avoid the same risks when hydrogen will be traded based on its GHG emissions. The appropriate methodological approach for each production pathway should be chosen by policymakers in collaboration with the LCA community and stakeholders from the industry based on the potential market and environmental consequences of such choice. • LCA methodologies for hydrogen-related policies are currently not fully harmonized. • Four hydrogen production pathways involving multifunctionality were analysed. • GHG emissions of hydrogen vary significantly with the LCA methodology adopted. • Inconsistencies can lead to market distortions, inefficiencies, and confusion. • There is an urgent need for harmonized and strict LCA guidelines for H2 production. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. Mo-based bimetallic oxide catalysts for the reverse water gas shift reaction.
- Author
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Dai, Hui, Deng, Xiaobing, Zhang, Anhang, Zhu, Yongqing, Xiao, Xin, Wang, Yan, and Zhou, Changjian
- Subjects
- *
WATER gas shift reactions , *BIMETALLIC catalysts , *CERIUM oxides , *WATER-gas , *CARBON dioxide - Abstract
The reverse water gas shift (RWGS) is of great significance to the resource utilization of CO 2. In this paper, based on the features of MoO 3 , the Mo-based catalysts doped with Ga, Ti and Ce were prepared, and the effects of oxygen vacancies and basic sites on the RWGS reaction were studied. When the volume ratio of H 2 and CO 2 is 1 : 1, the yield of CO can reach 26.66%. Because it exposes higher concentration of Ce sites and moderate alkaline active sites on the surface. When the proportion of H 2 in the reaction gas increases, the highest yield of CO can reach 54.53%, which is mainly attributed to a large number of oxygen vacancies on the surface of MoTi. This study can be used as a reference for the design of catalysts for RWGS reaction under different reaction conditions. A series of Mo-based catalysts were prepared, and the significance of oxygen vacancies and surface basic sites in RWGS reaction was explored, and a reference was provided for the study of similar catalytic materials under different reaction gas ratios. [Display omitted] • MoO 3 by doping transition metal has a good application prospect in RWGS reaction. • The yield of MoTi and MoCe is close to equilibrium in RWGS reaction. • High CO 2 concentration is good for MoTi with higher density oxygen vacancies. • High H 2 concentration is good for MoCe with higher density surface basic sites. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Transition metal dichalcogenides-based catalysts for CO2 conversion: An updated review.
- Author
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Khaidar, Dalilah Mohmad, Isahak, Wan Nor Roslam Wan, Ramli, Zatil Amali Che, and Ahmad, Khairul Naim
- Subjects
- *
TRANSITION metal catalysts , *NATURAL gas , *GREENHOUSE effect , *CARBON dioxide , *FOSSIL fuels , *COALBED methane , *PETROLEUM , *FORMIC acid - Abstract
The rapid depletion of fossil fuels has become the worst scenario as most of the energy needed still depends on the use of fossil energy, oil, natural gas, and coal. The combustion of crude oil and coal has contributed to the major anthropogenic carbon dioxide (CO 2) gas in the atmosphere and has worsened climate change and global warming. Therefore, the abundant CO 2 in the surrounding has opened the door to many studies to convert CO 2 into the next generation of fuels and indirectly reduce the greenhouse effect. Transition metal dichalcogenides (TMDs) nanomaterials have appeared as a practical and reliable catalyst for CO 2 conversion to sustainable fuels under normal atmospheric conditions. Having fascinating electronic and catalytic properties, these earth-abundant element-based materials are being explored and developed for real-world application. This paper reviews the recent insight into the synthesis, properties and application of TMDs as catalysts in electrocatalysis, photocatalysis and thermal catalysis for CO 2 reduction and conversion. The role of type of sulfide (S), selenide (Se) and telluride (Te)-based TMDs in the production of various valuable products such as formate (HCO 2 −), formic acid (CH 2 O 2), methanol (CH 3 OH), and ethanol (CH 3 CH 2 OH), amongst others, will be discussed in detail. The possible reaction pathways and mechanisms and the relationship between tailoring the catalysts properties and CO 2 activation towards high CO 2 reduction and conversion efficiency will also be evaluated. • TMD catalysts have demonstrated promising performance in converting CO 2. • TMD catalyst can be used for electro-, photo- and thermal-catalytic CO 2 conversion. • The synthesis and characterization methods of TMD catalysts has been reviewed. • The different types of TMD catalysts and their potential have been investigated. • The mechanisms of all catalytic reactions have been examined. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Tuning of physicochemical and electronic characteristics of Cu-doped NiCo2O4 ternary inverse spinel oxides for effective electrocatalytic hydrogen evolution reaction.
- Author
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Nair, Durga S., Anil, Anaswara, Elias, Liju, Satyanarayana, N., Holla, Harish Kumar, and Shibli, S.M.A.
- Subjects
- *
HYDROGEN evolution reactions , *TRANSITION metal oxides , *SPINEL , *METALLIC oxides , *COPPER , *CARBON dioxide , *OXIDES - Abstract
The paper reports the development of Cu-doped NiCo 2 O 4 ternary inverse spinel oxides through microwave-assisted hydrothermal method as effective catalysts for alkaline hydrogen evolution reaction (HER). The effective and controlled doping of Cu to NiCo 2 O 4 lattice by the partial replacement of Ni2+/Ni3+ with Cu+/Cu2+ results in the fine-tuning of structural, morphological, and electronic characteristics, favourable for electrocatalytic HER. The study effectively correlates the influence of variation in the percentages of Cu-doping on the material properties and thereby the electrocatalytic characteristics. The experimental results indicate that Cu 0.10 Ni 0.90 Co 2 O 4 electrode having optimum Cu-doping (10%) as the best electrocatalyst with the lowest onset potential for hydrogen evolution (242.7 mV) and reduced overpotential (72.5 mV) values by following a Volmer – Heyrovsky mechanism during HER. The improvement in HER performance after Cu-doping is due to the generation of greater number of active sites and reduction in electronic band gap. The present work advantageously utilises the scope of microwave-assisted transition metal doping strategy to fine tune the physicochemical and electronic characteristics, favourable for electrocatalytic HER, and this may pave a new way for tuning the electrochemical properties of metal oxides for various applications. • Microwave-assisted hydrothermal synthesis is used effectively to develop Cu-doped NiCo 2 O 4. • Cu-doping to NiCo 2 O 4 lattice creates more oxygen vacancies and improves electronic conductivity. • Cu 0.10 Ni 0.90 Co 2 O 4 with 10% Cu-doping exhibits promising electrocatalytic activity towards HER. • Cu-doped NiCo 2 O 4 follows Volmer – Heyrovsky mechanism during alkaline HER. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Reduction in carbon dioxide and production of methane by biological reaction in the electronics industry
- Author
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Kwangkeun Choi, Jin Wook Chung, and Seungjin Kim
- Subjects
Membrane reactor ,Carbon dioxide reforming ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Inorganic chemistry ,Energy Engineering and Power Technology ,Condensed Matter Physics ,Pulp and paper industry ,Methane ,Industrial wastewater treatment ,chemistry.chemical_compound ,Fuel Technology ,Electromethanogenesis ,Carbon dioxide ,Electrochemical reduction of carbon dioxide ,Negative carbon dioxide emission - Abstract
Biological methane production is a more environmentally friendly technology for carbon dioxide reduction than physical and chemical methods. Carbon dioxide can be reduced biologically to methane with hydrogen as the reducing agent under anaerobic conditions. In this study, carbon dioxide discharged from the electronics industry was reduced biologically to methane using the hydrogen produced from electrochemical wastewater treatment. Electrocoagulation technology was applied to treat industrial wastewater and obtain hydrogen without oxygen production. On mixing and injecting the hydrogen and carbon dioxide that were emitted from the facility into an anaerobic reactor, the methane content that was discharged from the anaerobic reactor and the reduction rate of carbon dioxide were 92% and 98%, respectively. This technology, combined with electrocoagulation and biological reaction, reduces carbon dioxide levels and produces methane.
- Published
- 2013
28. Conversion of carbon dioxide and methane in biomass synthesis gas for liquid fuels production
- Author
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Shyamsundar Ayalur Chattanathan, Steven Taylor, and Sushil Adhikari
- Subjects
Carbon dioxide reforming ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Biomass ,Condensed Matter Physics ,Pulp and paper industry ,Methane ,Steam reforming ,chemistry.chemical_compound ,Fuel Technology ,Carbon dioxide ,Organic chemistry ,Carbon monoxide ,Syngas - Abstract
The premise of this research is to find whether methane (CH4) and carbon dioxide (CO2) produced during biomass gasification can be converted to carbon monoxide (CO) and hydrogen (H2). Simultaneous steam and dry reforming was conducted by selecting three process parameters (temperature, CO2:CH4, and CH4:steam ratios). Experiments were carried out at three levels of temperature (800 °C, 825 °C and 850 °C), CO2:CH4 ratio (2:1, 1:1 and 1:2), and CH4:steam ratio (1:1, 1:2 and 1:3) at a residence time of 3.5 × 103 gcat min/cc using a custom mixed gas that resembles biomass synthesis gas, over a commercial catalyst. Experiments were conducted using a Box-Behnken approach to evaluate the effect of the process variables. The average CO and CO2 selectivities were 68% and 18%, respectively, while the CH4 and CO2 conversions were about 65% and 48%, respectively. The results showed optimum conditions for maximum CH4 conversion was at 800 °C, CO2:CH4 ratio and CH4:steam ratios of 1:1.
- Published
- 2012
29. Supercritical water gasification of real biomass feedstocks in continuous flow system
- Author
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Nikolaos Boukis, Tülay Güngören Madenoğlu, Mehmet Sağlam, and Mithat Yüksel
- Subjects
food.ingredient ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,Condensed Matter Physics ,Pulp and paper industry ,Methane ,Potassium carbonate ,chemistry.chemical_compound ,Fuel Technology ,food ,chemistry ,Carbon dioxide ,Organic chemistry ,Hemicellulose ,Cellulose ,Trona ,Carbon monoxide ,Syngas - Abstract
In this study, supercritical water gasification of the selected five biomass samples (cauliflower residue, acorn, tomatoes residue, extracted acorn and hazelnut shell) was investigated. Lignocellulosic feedstocks were gasified in a continuous flow reactor at 600 °C and 35 MPa. The product gas is composed of hydrogen, carbon dioxide, methane, carbon monoxide and a small amount of C2 compounds. Quantitative analysis of product gas was performed by Gas chromatography device. Potassium carbonate (K2CO3) and Trona (Na2CO3·NaHCO3·2H2O) were used as catalysts. Carbon gasification efficiencies were improved by addition of these catalysts into the reacting system. Moreover, carbon gasification efficiency changes with type of biomass that includes different ratio of cellulose, hemicellulose and lignin. The H2 yield (mol gas/kg C in feed) of acorn in the presence of Trona was found to be 7 times higher than that of without catalyst.
- Published
- 2011
30. Life cycle assessment of hydrogen produced from potato steam peels
- Author
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Sebastien Humbert, Sylvestre Njakou Djomo, and Dagnija Blumberga
- Subjects
Hydrogen ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Raw material ,Condensed Matter Physics ,Pulp and paper industry ,Renewable energy ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Greenhouse gas ,Carbon dioxide ,Bioreactor ,Environmental science ,business ,Life-cycle assessment ,Hydrogen production - Abstract
Hydrogen from renewable energy is considered a promising alternative to traditional petroleum-based transportation fuels. Potato steam peels can be used as feedstock to produce hydrogen through fermentation processes. Life cycle assessment is used as an analytical tool to evaluate the main environmental benefits and burdens of using potato steam peals to produce hydrogen rather than to feed animals. Inventory data are derived from the literature and ecoinvent. Impacts are evaluated using IMPACT 2002+. The results show that producing hydrogen from potato steam peels offers clear advantages over a direct use of peels to feed animals. A factor of two to three is observed in the reduction of greenhouse gas emissions, in the savings of non-renewable resources and in the reduction of human health impacts. The two-stage bioreactor is observed to consume around 25 MJ and to emit between 1000 and 1500 g of CO 2 per kilogram of hydrogen produced.
- Published
- 2008
31. Experimental verification of various methods for biological hydrogen production
- Author
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Jaromír Lachman, Jaime O.J. Muñoz, Sergej Ust’ak, Eloy Fernández, and Bohumil Havrland
- Subjects
Hydrogen ,biology ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Condensed Matter Physics ,biology.organism_classification ,Photosynthesis ,Pulp and paper industry ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Biochemistry ,Algae ,Carbon dioxide ,Fermentation ,Green algae ,Scenedesmus ,Hydrogen production - Abstract
The aim of the work was to compare two different biological methods for hydrogen production: fermentative and photosynthetic based upon the modality of batch cultures. For testing of fermentative bio-hydrogen production four mixed cultures representing anaerobic microorganisms (dominant strain Clostridium ) were selected. The kinetic parameters on the intensity of bio-hydrogen production were established. The efficiency coefficient of transformation ranged from 1.65 mol H 2 /mol glucose in the pectin culture up to 2.45 in the mixed culture. The bio-hydrogen concentration never exceeded 30%. The carbon dioxide was produced in a ratio of CO 2 to H 2 (0.5–0.67)/1. The testing of green algae proved that the most effective was the algae species Scenedesmus . High bio-hydrogen purity was analytically verified. The fermentative method of H 2 production is more efficient; it does not need light, has a longer efficiency of one charge and enables effective use of different biological wastes.
- Published
- 2007
32. Research progress of bimetallic catalysts for CO2 hydrogenation to methane.
- Author
-
Wei, Chaojie, Ding, Honglei, Zhang, Ziyi, Lin, Feng, Xu, Yifeng, and Pan, Weiguo
- Subjects
- *
BIMETALLIC catalysts , *CARBON emissions , *CARBON dioxide , *GREENHOUSE effect , *CATALYTIC activity , *ACTIVATION energy - Abstract
It is well known that solving the greenhouse effect caused by increasing CO 2 emissions is urgent, and CO 2 methanation reaction is a popular research area as one of the effective ways. However, there are great obstacles and challenges to develop catalysts with higher stability and catalytic activity. In order to reduce the activation energy required for methanation reactions, it is expected to introduce another metal into monometallic catalysts to form bimetallic catalysts through the synergistic effect between the bimetallic phases. This paper reviews the advantages of metal-phase combinations for bimetallic catalysts applied to CO 2 methanation. The main synthetic methods used to prepare bimetallic catalysts in recent years are discussed. The effects of bimetallic phase synergy, bimetallic phase structure, metal particle size and dispersion, metal component ratio, and carrier effect on catalyst performance are analyzed. Finally, the challenges and application prospects of bimetallic catalysts for CO 2 methanation are presented. • Hydrogenation mechanisms for combinations of combination of dual active components are analyzed. • The preparation method and auxiliary preparation technology of bimetallic catalyst are discussed. • The synergistic effect between the two metal phases should sometimes be enhanced and sometimes suppressed. • The structure between the two metal phases improves the efficiency of the catalysts. • Different catalyst particle sizes affect product generation in CO2 hydrogenation reactions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Review of electrocatalytic reduction of CO2 on carbon supported films.
- Author
-
Yuda, Afdhal, Ebrahimi, Parisa, Selvaraj, Josephine, Kumar, Anand, and Subramanian, Vaidyanathan (Ravi)
- Subjects
- *
CARBON films , *CARBON-based materials , *TRANSITION metal oxides , *BIMETALLIC catalysts , *CARBON dioxide , *CARBON dioxide reduction , *ELECTROLYTIC reduction , *SOLVENTS , *ATMOSPHERIC carbon dioxide - Abstract
Carbon capture and conversion are becoming increasingly important as atmospheric CO 2 concentrations rise and their adverse effects become increasingly evident. CO 2 conversion/utilization-related research has gained renewed interest on a variety of platforms, including thermal, solar, biological, photochemical, and electrochemical conversions. Electrochemical routes, using suitable catalysts, are potentially suitable for commercial purposes owing to ease of integration with solvent-based carbon capture processes. This paper summarizes and evaluates the studies conducted within the past decade regarding the feasibility of carbon-based supports utilized in electrocatalytic carbon dioxide reduction. CO 2 conversion has been reviewed in a number of reports, focusing on specific sections, such as metallic/bimetallic catalysts, CO 2 solubility, and the fabrication of electrodes and electrochemical cells. The number of publications addressing various carbon-based electrocatalysts is increasing, but these materials have not yet been reviewed. Herein, we are focused on three types of electrocatalyst materials: metals, metal-oxides, non-oxides, and combinations thereof with carbon. The scope of this study includes the following: i) carbon-based materials and how they are characterized by distinctive properties, ii) electrocatalytic CO 2 conversion techniques, and iii) research cases for carbon allotrope-supported composites used in CO 2 reduction. The advancement in analytical tools that provide insight into liquid-phase reactions will benefit the development of catalysts and electrodes that will be effective in converting CO 2 into the desired products. Such developments will also be applicable to other systems involving liquid electrolytes or solvents for performing reactions on catalyst surfaces. • A comprehensive review of carbon-based electrocatalysts for CO 2 conversion. • High conductivity of carbon-based materials is suited for superior charge transfer. • Their large surface areas helps in dispersing and stabilizing active sites. • Transition metal oxides provide a large distribution of products in CO 2 reduction. • Catalysts composition and structure govern CO 2 activity and product distribution. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Parametric analysis of a modified ammonia-hydrogen-electricity cogeneration system.
- Author
-
Kang, Zongyao, Liu, Bin, She, Xiaohui, Liu, Wei, Huang, Jingzhong, and Wang, Kaihui
- Subjects
- *
BRAYTON cycle , *COGENERATION of electric power & heat , *HYDROGEN production , *ENERGY consumption , *RANKINE cycle , *CARBON dioxide , *HYDROGEN storage , *NUCLEAR energy - Abstract
In this paper, a novel ammonia-hydrogen-electricity cogeneration system is developed. To mitigate the cost associated with hydrogen storage and transportation in later stages, the proposal is to utilize high-temperature ammonia production instead of conventional hydrogen production. A comparative analysis between ammonia and transportation for hydrogen is conducted to assess cost efficiencies. To improve the system efficiency, a supercritical CO 2 Brayton cycle is applied as the power generation cycle. This choice exhibits superior parameter compatibility with the system compared to the Rankine cycle. The study scrutinizes the impacts of different energy utilization sequences and varying process parameters of the power generation cycle on the system's performance to ascertain the most optimal configuration. The results indicate that the Brayton cycle is more suitable for integration with the nuclear-IS thermochemical hydrogen production system, significantly enhancing the power generation capacity of the ammonia-hydrogen-electricity cogeneration system. These improvements result in 18.8 % increase in power generation efficiency and a 9.3 % boost in overall energy efficiency of the system. Subsequent to this enhancement, the system attains an impressive energy efficiency of 47.0 % along with a system exergy efficiency of 63.4 %. This study introduces an innovative approach for optimizing and enhancing the energy efficiency of a cogeneration system by employing nuclear energy as a high-temperature heat source for hydrogen (ammonia) production. • A novel ammonia-hydrogen-electric cogeneration system is developed. • The system bolsters efficiency by 9.3 % through a synergistic Brayton cycle coupling. • Conducted an assessment and comparison of the transportation and storage expenses associated with hydrogen and ammonia. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. A parametric study on hydrogen production by fluidized bed co-gasification of biomass and waste plastics.
- Author
-
Erdem, Kaan, Gündüz Han, Duygu, and Midilli, Adnan
- Subjects
- *
PLASTIC scrap , *BIOMASS gasification , *HYDROGEN production , *COAL gasification , *HIGH density polyethylene , *BIOMASS , *CARBON dioxide - Abstract
This paper presents a parametric study on hydrogen production potential from biomass and waste plastics via fluidized bed co-gasification technique by using different gasifying agents such as steam, air and CO 2. In this regard, a new Aspen Plus model representing this process was developed. For this purpose, first, a comparative feedstock selection between several materials was performed, ultimately identifying the cotton husk (CH) and high-density polyethylene (HDPE) mixture as the most promising choice. Secondly, the study focused on steam co-gasification of CH with HDPE to assess the impact of various factors, including plastic content in feedstock, temperature, steam to feedstock ratio (S/F), and the introduction of gasifying agents, namely air and CO 2, next to steam. The analysis mainly examined the influence of these parameters on the composition of syngas, calorific value, and the hydrogen production. Accordingly, it was determined that an increase in plastic content and S/F ratio resulted in higher hydrogen concentration in the syngas, and the maximum quantity of H 2 with 1189.3 Nm3/ton feed was produced at 900 °C. In addition, co-utilization of air or CO 2 with steam as a gasifying agent deteriorated the system performance regarding H 2 yield. Thus, it is expected that the model developed will contribute to the researchers, investors, engineers and policy maker working on the gasification technology for hydrogen production. [Display omitted] • Possible mixtures of various biomass and plastics for co-gasification was compared. • H 2 production from cotton husk and HDPE co-gasification showed promising results. • Use of steam, steam & air and steam & CO 2 as gasification agent was studied. • Co-gasification of mixtures with more plastic content yielded greater hydrogen. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Highly stable hierarchical core-shell structure CuMn0.5Co2O4@CC with self-regulating electronic and conductivity for its improved OER performance.
- Author
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He, Xuanmeng, Jing, Yunxiang, Wang, Louqian, Zhang, Zeqin, Liu, Hui, and Wang, Xinzhen
- Subjects
- *
HYDROGEN evolution reactions , *OXYGEN evolution reactions , *CARBON dioxide , *ELECTRONIC structure , *ELECTRIC conductivity , *STRUCTURAL stability , *METALLIC composites - Abstract
Improving the catalytic activity and long-term stability of catalysts have always been the goal of its application. The structure stability and good electrical conductivity of catalysts are the key to OER performance, which have been challenge for application of catalysts. In the paper, we designed an in-situ growth of hierarchical core-shell structure CuMn 0.5 Co 2 O 4 @CC with superior conductivity directly as the catalytic electrode for improved OER performance. The well-standing CuMn 0.5 Co 2 O 4 nanoneedles with mesoporous structure entirely encapsulated on the carbon fibers, exposing a large special surface area and structural stability, while carbon fibers improved its electrical conductivity. Meanwhile, the richer oxygen vacancies and self-regulating electronic structure by the diversification of the metal oxidation state in the catalyst would promote the OER activity and stability. Benefitting from these merits, the requiring overpotential of CuMn 0.5 Co 2 O 4 @CC was 189 mV at the current density of 10 mA cm−2 and the Tafel slop value was 64.1 mV⋅dec−1, which was lower than that of CuMn 0.5 Co 2 O 4 //CC (η 10 = 337 mV and Tafel slop value of 113.9 mV⋅dec−1). In addition, the CuMn 0.5 Co 2 O 4 @CC had a competitive stability of with the current retention rate of 95.3 % after 1000 cycles. The present work provide a useful attempt to construct highly catalytic active and durably stable metal oxide composite catalysts. The synthesized CuMn 0.5 Co 2 O 4 @CC electrode exhibited the excellent OER activity (η 10 = 189 mV and Tafel slope of 64.1 mV⋅dec−1) and higher stability (the current retention rate of 95.3 % after 1000 cycles), which was attributed to the excellent conductivity of carbon fiber, the large surface area of active ingredients, and the regulated electronic structure with adjacent elements. [Display omitted] • The large special surface area and coupled with high structural stability for CuMn 0.5 Co 2 O 4 @CC catalyst. • The richer oxygen vacancies and self-regulating electronic structure promote the OER performance. • The improving OER activity and stability was attributed to the synergetic coupling effect between CC and CuMn 0.5 Co 2 O 4. • A lower overpotential of 189 mV, Tafel slop of 64.1 mV⋅dec−1, and the current density retention of 95.3 % were obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. NO emission characteristics for the HTC and MILD combustion regimes with N2, N2/CO2 and CO2 diluents: effect of H2 addition to CH4.
- Author
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Fordoei, Esmaeil Ebrahimi and Boyaghchi, Fateme Ahmadi
- Subjects
- *
COMBUSTION , *METHANE , *CARBON dioxide , *NITROGEN , *NUMERICAL calculations - Abstract
In this paper, the effect of H 2 addition to CH 4 on the NO emission of oxy-fuel, oxygen-enriched, and air-fuel MILD combustion is studied by numerical and chemical calculations. In the CFD section, the University of Lisbon MILD furnace is modeled. The results show that H 2 added to CH 4 is associated with a higher NO emission in the same oxidant composition. It is due to higher NO formation by NNH and thermal mechanisms. It can be found that by transformation from air-fuel to oxy-fuel MILD regimes, NO emission is reduced significantly. Moreover, the addition of H 2 prevents flame extinction that often occurs under MILD conditions when CO 2 replaces N 2. Reaction pathway analysis displays that dominant routes of NO emission in the H 2 -lean are N 2 O-intermediate for the air-fuel and oxygen-enriched conditions and NNH for the oxy-fuel MILD regime. In the H 2 -rich condition, the NNH mechanism plays the most important role in the NO production. • X H2,cr is known that in the higher values of it, NO emission increases dramatically. • H 2 added to CH 4 prevents flame extinction due to the replacement of CO 2 with N 2. • Change of diluent form N 2 to CO 2 reduces significantly NO emission under MILD regime. • H 2 -lean shows N 2 O-intermediate as main NO mechanism of air-fuel and oxygen-enriched. • NNH is the main route in the NO emission of CH 4 /H 2 -rich MILD regime. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Enhanced CO2 hydrogenation to light hydrocarbons on Ni-based catalyst by DBD plasma.
- Author
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Ullah, Niamat, Su, Meng, Yang, Yuwang, and Li, Zhenhua
- Subjects
- *
METHANATION , *HYDROGENATION , *CARBON dioxide , *EMISSION spectroscopy , *NONEQUILIBRIUM plasmas , *CATALYSTS , *THERMAL plasmas - Abstract
The high thermal stability of CO 2 makes its conversion low in conventional thermal catalysis. Comparatively, non-equilibrium plasma technique provides an efficient way for CO 2 hydrogenation under mild reaction conditions. Introducing effective catalysts to the dielectric barrier discharge (DBD) plasma reactor may further improve CO 2 hydrogenation performance. In this way, the interaction between plasma and catalysts is important to contribute CO 2 hydrogenation performance. Considering Ni-based catalyst is active for CO 2 hydrogenation, we used three different kinds of carrier materials including CeO 2 , γ-Al 2 O 3 and ZSM-5 as supports to prepare nickel-based catalysts by incipient impregnation in this paper. The supported Ni catalysts were tested for the plasma-induced CO 2 hydrogenation to CH 4 and C 2+ hydrocarbons in the DBD-plasma reactor. It was found that the 15Ni/CeO 2 catalyst achieved the best CO 2 conversion of 85.7% and nearly 100% CH 4 selectivity at 300 °C due to its high reducibility and CO 2 chemisorption capacity. In addition, a significant synergistic effect was found between DBD plasma and catalyst. The performance of plasma-catalysis was considerably better than that of thermal catalysis plus pure plasma reaction, and the synergistic effects were enhanced with increase of reaction temperature. Moreover, the mechanism of the synergistic effect was proposed by analyzing the optical emission spectroscopy (OES) of DBD plasma, which provides a theoretical basis for further optimizing and application of plasma-catalysis for CO 2 hydrogenation reaction. [Display omitted] • CO 2 hydrogenation to CH 4 and C 2+ hydrocarbons was enhanced by plasma-catalysis. • The 15Ni/CeO 2 showed better activity due to better reducibility and CO 2 chemisorption ability. • A synergistic effect between plasma and catalyst was enhanced with increase in reaction temperature. • The synergistic mechanism between plasma and catalysts was proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Promotion effect of different lanthanide doping on Co/Al2O3 catalyst for dry reforming of methane.
- Author
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Liang, Zhoujie, Zhang, Yu, Zhang, Guojie, Liu, Jun, Cai, Yajing, Wang, Ying, Zhao, Yuqiong, Li, Guoqiang, and Bei, Kunlun
- Subjects
- *
STEAM reforming , *RARE earth oxides , *RARE earth metals , *CARBON dioxide adsorption , *COBALT catalysts , *CATALYSIS , *METALLIC oxides - Abstract
In this paper, a series of cobalt catalysts modified by different lanthanide metals were synthesized via co-impregnation method using inexpensive industrial-grade alumina as a support for dry reforming of methane. The effect of lanthanide metals as accelerators of cobalt-based catalysts on catalytic performance and anti-coking properties was mainly investigated. The textural relationships between the catalytic performance and physicochemical properties of cobalt-based catalysts doped with different lanthanide metals were further investigated. Different characterization techniques demonstrate the positive effect of lanthanide metals on the physicochemical properties of catalysts. The results show that the electron transfer between cobalt species and lanthanide metal oxides is significantly enhanced due to the introduction of lanthanide elements. The process generates more active sites, which is favorable for the adsorption and activation of methane. In addition, the abundant medium basic sites and oxygen vacancies on the surface of cobalt-based catalysts with the effect of lanthanides promoted the adsorption and activation of carbon dioxide and the gasification of carbon accumulation, which greatly improved the anti-carbon accumulation performance of the catalysts. Therefore, the prepared cobalt-lanthanum-based catalysts showed the best catalytic effect and have great potential for application. • The introduction of lanthanides enhances the electron transfer ability of Co species. • The introduction of lanthanides enhanced the anti-coking performance of the catalyst. • The introduced lanthanides provide abundant active sites for the activation of CH 4 and CO 2. • It provides an efficient and economical strategy for the industrial application of dry methane reforming. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
40. EDTA impregnation assisted synthesis of nickel nanoparticles embedded in activated carbon and its application for dry reforming of methane.
- Author
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Qin, Linbo, Hu, Ziqin, Hu, Mufang, Zhao, Bo, Kong, Lingtian, Chen, Wangsheng, and Han, Jun
- Subjects
- *
ACTIVATED carbon , *METHANE , *ETHYLENEDIAMINETETRAACETIC acid , *NICKEL catalysts , *STEAM reforming , *CARBON dioxide - Abstract
In this paper, the catalysts with nanoscale nickel particles embedded in activated carbon were synthesized by Ethylenediaminetetraacetic acid (EDTA) assisted impregnation method. The experimental results revealed that EDTA addition could promote Ni particle dispersion and decrease Ni particle size. Ni particle size was significantly decreased from 18.23 to 4.57 nm when Ni/EDTA ratio was increased from 1:0 to 1:3. Catalytic performance of Ni 15 -AC-E 3 demonstrated that CH 4 and CO 2 conversion rate under 850 °C were 90.05% and 96.28%, which were decreased by 1.08% and 1.27% after 72 h dry reforming methane (DRM) reaction. Moreover, the characteristic of the used catalyst showed that Ni particle size was only increased from 4.57 to 5.94 nm after the stability test, and NiO was not appeared. Meanwhile, the deposited carbon in the used catalyst was 5.02%. The above results meant that the catalyst prepared by EDTA assisted impregnation method had the ability of suppressing carbon deposition, Ni particle sintering and oxidation during DRM reaction. • EDTA addition could promote Ni particle dispersion and decrease Ni particles size. • The average Ni particle diameter in Ni 15 -AC-E 3 was only 4.57 nm. • CH 4 and CO 2 conversion rate over Ni 15 -AC-E 3 under 850 °C were 90.05% and 96.28%. • CH 4 and CO 2 conversion rate were only decreased by 1.08% and 1.27% after 72 h reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Performance and durability of metal-supported solid oxide electrolysis cells at intermediate temperatures.
- Author
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Wang, Zhongxu, Wang, Yue, Li, Naizhi, Tong, Yongcheng, Teng, Yue, Wang, Di, Chen, Chusheng, and Zhan, Zhongliang
- Subjects
- *
HIGH temperature electrolysis , *ELECTROLYSIS , *CARBON dioxide , *METALLIC oxides , *OHMIC resistance , *WIND power , *STAINLESS steel , *STAINLESS steel corrosion - Abstract
Metal-supported solid oxide electrolysis cells (MS-SOECs) operating at 600–700 °C are attractive for storage of intermittent renewable electricity from solar and wind energy due to their advantages of easy sealing and fast startup. This paper reports on the fabrication of MS-SOECs consisting of dense scandium stabilized zirconia (SSZ) electrolytes, Ce 0.8 Sm 0.2 O 2−δ (SDC)/Ni impregnated 430L/SSZ cathodes and SmBa 0.5 Sr 0.5 Co 2 O 5+δ (SBSCO) impregnated SSZ anodes supported on porous 430L alloys. Such cells demonstrated excellent electrolysis performance with current densities at 650 °C as high as 0.73 A⋅cm−2 at 1.3 V in 50% H 2 O-50% H 2 and 0.95 A⋅cm−2 at 1.5 V in 90% CO 2 -10% CO. Electrochemical impedance measurements indicated that the cell performance was largely limited by the ohmic losses for steam electrolysis and by the cathodic reduction reactions for CO 2 electrolysis, especially at reduced temperatures. Pronounced degradation was observed for both steam and CO 2 electrolysis over the preliminary 90-h stability measurements at 600 °C. SEM examination and EDS mapping of measured cells showed significant aggregation and coarsening of impregnated Ni particles, resulting in smaller activities for H 2 O and CO 2 reduction reactions. As evidenced by the almost unaltered ohmic resistances over the measurement durations, the 430L stainless steel substrates demonstrate excellent resistances against corrosions from H 2 O and CO 2 and thus show great promise for applications in reduced-temperature MS-SOECs. • 430L stainless steel is applied as the support of SOECs. • Ce 0.8 Sm 0.2 O 1.9 /Ni and SmBa 0.5 Sr 0.5 Co 2 O 5+δ are impregnated into the scaffolds. • The MS-SOECs show excellent performance at intermediate temperatures of 600–700 °C. • Coarsening of impregnated Ni particles is the main reason for degradation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. The upper thermal efficiency and life-cycle environmental assessment of nuclear-based hydrogen production via splitting H2S and CO2.
- Author
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Liu, Hong, Zhou, Zuoyong, Lv, Wendong, Ye, Haotian, and Dong, Hongguang
- Subjects
- *
THERMAL efficiency , *PRODUCT life cycle assessment , *CARBON emissions , *INTERSTITIAL hydrogen generation , *NUCLEAR energy , *CARBON dioxide , *HYDROGEN as fuel , *HYDROGEN production - Abstract
It is proposed to develop a novel thermochemical cycle using nuclear energy to decompose H 2 S and CO 2 , thus producing H 2 and CO from acidic gas in petrochemical or coal chemical industries, reducing CO 2 emissions and promoting sustainable energy development. The upper limits and significant energy-consuming steps were determined based on two chemical routes of the thermochemical cycle systems 1 and 2. When the enthalpy of the H 2 S oxidation reaction served as part of the circulating energy input, the values for system 1 and system 2 were 38.7% and 34.3%, respectively. However, if only external energy is considered to satisfy the heat and work required to run the reaction and pump, the thermal efficiency rises to 58.4% and 61.2%, respectively. The life cycle assessment (LCA) was used to investigate the environmental effect of the hydrogen generation process base on the upper thermal efficiency in this study, and the results of the LCA are stated in terms of global warming potential (GWP) and acidification potential (AP). The GWP of systems 1 and 2 was calculated as 2.59 kg CO 2 -eq/kg H 2 , 2.54 kg CO 2 -eq/kg H 2 , The AP of systems 1 and 2 was calculated as 7.48 g SO 2 -eq/kg H 2 and 9.08 g SO 2 -eq/kg H 2 , respectively. This paper assesses the environmental effect of two different hydrogen systems used in manufacturing various subsystems in GWP and AP, and compares them to the life cycle of other hydrogen production pathways. • A novel thermochemical cycle using nuclear energy to split H 2 S-CO 2 is proposed. • Energy-consuming steps and the upper thermal efficiency were determined. • The upper thermal efficiency has been developed to assess environmental impacts. • The LCA integrated China's HTR-PM with the innovative H 2 S-CO 2 process. • GWP and AP in the H 2 S-CO 2 system are compared to other hydrogen methods. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Experimental research on a blended hydrogen-fuel engine.
- Author
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Zhunqing, Hu, Nannan, Sun, Yi, Jia, and Xin, Zhang
- Subjects
- *
HYDROGEN as fuel , *ENGINE cylinders , *GAS as fuel , *INTERNAL combustion engines , *ENGINES , *CARBON dioxide - Abstract
An experimental study on the performance of a single cylinder engine fueled with hydrogen/gas fule blends was carried out. The performance of engine with different fuel components under the load characteristics of the engine was analyzed. The experimental results showed that with the increase of hydrogen blending ratio, the combustion speed was accelerated, and the maximum torque and maximum pressure in the cylinder were increased; The maximum torque of blended fuel with 40% CO 2 was 68.3% of that without CO 2 ; The maximum pressure in cylinder of blended fuel with 40% H 2 was 1.6 times higher than that without hydrogen; When the proportion of hydrogen was more than 30%, the torque decreased; When the mixture was blended with 30% N 2 , the engine torque reached the maximum at the hydrogen ratio of 15%; With the increase of hydrogen blending ratio, the emission of CO increased and the emission of HC and NOx decreased; When the hydrogen blending ratio remained unchanged, the CO emission was the largest at medium load, the HC emission was the largest at small load, and the NOx emission was the largest at high load; When the mixture was blended with 15% H 2 , with the increase of the proportion of nitrogen, emission of CO decreased, emissions of HC and NOx increased. The research of this paper provided an experimental basis for the design and development of gas fuel engines. • The maximum torque and the maximum pressure in the cylinder increase with the increase of H 2 ratio in mixture. • When the throttle opening is fixed,the engine torque of mixture blended with 15% H 2 is the maximum. • Engine power is affected by both the combustion speed and the calorific value of the mixture. • With the increase of hydrogen blending ratio, CO increases and HC and NOx decreases. • Remain H 2 unchanged, with the increase of N 2 , CO decreases, HC and NOx increase. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. Modelling the performance of an SOEC by optimization of neural network with MPSO algorithm.
- Author
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Han, Jing, Wang, Xi, Yan, Limei, and Dahlak, Aida
- Subjects
- *
HYDROGEN economy , *PARTICLE swarm optimization , *GAS mixtures , *CARBON dioxide , *ENERGY consumption , *HYDROGEN as fuel - Abstract
This paper studies the Solid Oxide Electrolyzer Cell as a promising system in the sustainable development for the hydrogen economy and energy systems as a robust system. The Solid Oxide Electrolyzer Cell converts the steam and carbon-dioxide directly to functional fuels through consumption of the additional electrical power of green power sources or off-peak network powers. The present paper evaluates the static efficiency of the SOEC under four various gas mixtures. Modeling of this system is performed using Elman neural network (ENN) and modified particle swarm optimization (MPSO) algorithm. The MPSO algorithm is utilized to determine the optimal values for ENN adjustable parameters. It's known from the empirical results that the steam and carbon-dioxide concentrations can affect the SOEC efficiency. The operational potential and volume share of the hydrogen, carbon dioxide and steam are considered as the system inputs, and efficiency (current) is remarked as its output. The correlation factors of the achieved model are greater than 0.999, and its MSE (mean squared error) is lower than 0.017. It reveals that the forecasted values are almost equal to the empirical data. Subsequently, the efficiency of the SOEC is studied using the achieved model of the MPSO-based ENN in various feedstock concentrations. Thus, this dataset that is used for ENN model can be desirable for different applications of fast-modeling in a standalone group. It as well can be useful for cost, computing-time, and computing burden reduction in a model construction in the efficiency analyzing and system-level designing processes. • The static model of a SOEC is identified in this paper. • Elman neural network is applied in this paper as a novel method in the modeling process. • MPSO algorithm is used to increase the accuracy of the obtained model. • Static efficiency of the SOEC is evaluated for various gas mixtures. • The obtained results demonstrated the high precision of the proposed model. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
45. Production of hydrogen by microbial fermentation
- Author
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D. Cox, M. Levandowsky, and S. Roychowdhury
- Subjects
chemistry.chemical_classification ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Starch ,Pulp (paper) ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Maltose ,engineering.material ,Condensed Matter Physics ,Polysaccharide ,chemistry.chemical_compound ,Fuel Technology ,Biochemistry ,Carbon dioxide ,engineering ,Fermentation ,Food science ,Cellulose - Abstract
Production of hydrogen by defined and undefined bacterial cultures was studied, using pure sugars (glucose and maltose) or natural sources rich in either pure sugars or polysaccharides. The latter included sugar cane juice, corn pulp (enzymatically treated or untreated), and enzymatically treated paper. Mixed microbial flora from sewage and landfill sediments, as well as pure and mixed cultures of known coliform bacteria produced mixtures of hydrogen and carbon dioxide at 37°C and 55°C, with hydrogen concentrations as high as 87%. In the case of the pure glucose substrate, an average yield of 0.7 mol hydrogen per mol glucose was obtained.
- Published
- 1988
46. Effects of CO2 addition on deflagration characteristics of syngas-air premixed mixtures in T-pipeline.
- Author
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Wei, Shengnan, Deng, Haoxin, Xu, Zhuangzhuang, Yan, Mengmeng, Wen, Xiaoping, Wang, Fahui, and Chen, Guoyan
- Subjects
- *
CHEMICAL kinetics , *FLAME spread , *CARBON dioxide , *PRESSURE sensors , *FLAME - Abstract
With the industrial application of syngas, the explosion accident caused by it has gradually become a topic of concern for researchers. In this paper, the effects of CO 2 addition on the deflagration characteristics of syngas-air premixed mixtures were investigated through experiments and numerical simulations. Experiments were carried out inside a T-pipeline, using a high-speed camera and a pressure sensor to simultaneously record the flame evolution and pressure dynamics during deflagration. Simulations were calculated using the GRI 3.0 mechanism by Chemkin Premix Code. The results show that the addition of CO 2 has a certain inhibitory effect on the flame propagation, which can make the finger flame in the vertical pipe evolve into a "tulip" flame. And under the inhibition of CO 2 , the deflagration overpressure of the mixture is reduced, and the number of H, O, OH radicals is also greatly reduced, and the chemical reaction rate is correspondingly slowed down. [Display omitted] • The flame spreads symmetrically in the T-pipeline. • The addition of CO 2 can inhibit the flame propagation in the T-pipeline. • The more CO 2 added, the lower the T-pipeline explosion overpressure. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
47. Constructing rod-shaped Co2C/MoN as efficient bifunctional electrocatalyst towards overall urea-water electrolysis.
- Author
-
Zhang, Lingye, Wang, Yingxi, Cao, Jie, Zhang, Rui, Wang, Feng, and Wu, Huimin
- Subjects
- *
FOAM , *OXYGEN evolution reactions , *HYDROGEN evolution reactions , *ELECTROLYSIS , *CARBON dioxide , *HYDROGEN production - Abstract
In this paper, Co 2 C/MoN/NF at different calcination temperatures (T = 500, 550, 600, 650, 700 °C) was prepared in situ on 3D foam nickel (NF) by hydrothermal treatment and high-temperature calcination. The experimental results show that the sample synthesized at 600 °C (Co 2 C/MoN-600/NF) has the best catalytic capacity and the maximum electrochemical active area. For the hydrogen evolution reaction (HER), the potential is only −176 mV at 100 mA cm−2, meanwhile, only 1.42 V is needed for urea oxidation reaction (UOR). Furthermore, a two-electrode electrolyze cell of Co 2 C/MoN-600/NF‖Co 2 C/MoN-600/NF was constructed. And the voltage required for overall urea splitting (OUS) is 1.507 V at 50 mA cm−2, which is 171 mV lower than that of overall water splitting (OWS, 1.678 V). Moreover, the prepared catalyst not only can treat urea in wastewater but also catalyze the production of hydrogen. Therefore, it will be a promising green electrocatalyst. [Display omitted] • Co 2 C/MoN / NF was synthesized at different calcination temperatures for producing hydrogen energy. • Co 2 C/MoN / NF exhibited efficient bifunctional electrocatalyst towards HER and UOR. • Compared with pure water splitting, the efficiency of the catalyst is higher with the aid of urea. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
48. Glycine-assisted preparation of highly dispersed Ni/SiO2 catalyst for low-temperature dry reforming of methane.
- Author
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Yang, Jiliang, Lu, Xinkang, Han, Cui, Liu, Hui, Gong, Dandan, Mo, Liuye, Wei, Qinhong, Tao, Hengcong, Cui, Sha, and Wang, Luhui
- Subjects
- *
CATALYSTS , *METHANATION , *METHANE , *GLYCINE receptors , *CARBON dioxide , *LOW temperatures , *HIGH temperatures - Abstract
Ni-based catalysts have been widely studied in reforming methane with carbon dioxide. However, Ni-based catalysts tends to form carbon deposition at low temperatures (≤600 °C), compared with high temperatures. In this paper, a series of Ni/SiO 2 -XG catalysts were prepared by the glycine-assisted incipient wetness impregnation method, in which X means the molar ratio of glycine to nitrate. XRD, H 2 -TPR, TEM and XPS results confirmed that the addition of glycine can increase Ni dispersion and enhance the metal-support interaction. When X ≥ 0.3, these catalysts have strong metal-support interaction and small Ni particle size. The Ni/SiO 2 -0.7G catalyst has the best catalytic performance in dry reforming of methane (DRM) test at 600 °C, and its CH 4 conversion is 3.7 times that of Ni/SiO 2 -0G catalyst. After 20 h reaction under high GHSV (6 × 105 ml/g cat /h), the carbon deposition of Ni/SiO 2 -0.7G catalyst is obviously lower than that of Ni/SiO 2 -0G catalyst. Glycine-assisted impregnation method can enhance the metal-support interaction and decrease the metal particle size,which is a method to prepare highly dispersed and stable Ni-based catalyst. [Display omitted] • Highly dispersed Ni/SiO 2 -XG catalysts were prepared by glycine-assisted impregnation. • The Ni/SiO 2 -0.7G shows high activity and coke resistance during low-temperature DRM. • Excellent activity and coke resistance is due to the high Ni dispersion. • Highly dispersed Ni was stable due to the strong metal-support interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
49. Comparative analyses of a novel solar tower assisted multi-generation system with re-compression CO2 power cycle, thermoelectric generator, and hydrogen production unit.
- Author
-
Khanmohammadi, Shoaib, Kizilkan, Onder, and Musharavati, Farayi
- Subjects
- *
HYDROGEN production , *THERMOELECTRIC generators , *SUPERCRITICAL carbon dioxide , *INTERSTITIAL hydrogen generation , *REMANUFACTURING , *WASTE recycling , *SOLAR power plants , *CARBON dioxide - Abstract
In the present paper, a new energy generation system is suggested for multiple outputs, including a hydrogen generation unit. The plant is powered by a solar tower and involves six different subsystems; supercritical carbon dioxide (sCO 2) re-compression Brayton cycle, ammonia-water absorption refrigeration cycle, hydrogen generation, steam generation, drying process, and thermoelectric generator. The thermodynamic assessment of the multi-generation system is carried out for three different cities from Turkey, Iran, and Qatar. The energy and exergy efficiencies are calculated for base conditions to compare the different locations. The operating output parameters for the suggested system and simple re-compression Brayton system are compared. A parametric analysis is also done for investigating the influences of different system variables on plant performance. According to the results, Doha city is found to be more effective due to its geographical conditions. Moreover, based on the comparative study, the proposed cycles produce more power than the basic re-compression cycle with 64.59 kW, 47.33 kW, and 52.25 kW for Doha, Isparta, and Tehran, respectively. Additionally, the analyses revealed that in the term of energy efficiency, the suggested system has 32.29%, 32.28%, and 32.29% better performance than the simple cycle, and in terms of exergy efficiency, it has 4%, 4.8%, and 5% better performance than the simple cycle in Doha, Isparta, and Tehran, respectively. • A new integrated energy system with maximum waste recovery introduced. • Three different cities in Turkey, Iran and Qatar were select for system analysis. • The average annual rate of hydrogen production for Doha is 6.48 kg/h. • Suggested system in Isparta has 2070 kW more exergy destruction than basic system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
50. Supercritical water gasification of oil-containing wastewater with a homogeneous catalyst: Detailed reaction kinetic study.
- Author
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Xu, Jialing, Cheng, Zening, Ren, Changsheng, Yi, Lei, Wei, Wenwen, Jin, Hui, and Guo, Liejin
- Subjects
- *
SUPERCRITICAL water , *WATER-gas , *SEWAGE , *WASTEWATER treatment , *HYDROGEN production , *CATALYSTS , *CARBON dioxide - Abstract
Supercritical water gasification (SCWG) is a promising technology for oil-containing wastewater treatment. This paper aims to establish a reaction kinetic model to provide better guidance for optimal industrial reactor design. The model is developed based on the experimental results obtained from K 2 CO 3 -catalyzed SCWG of diesel (the model compound of oil containment in wastewater) at various conditions of 500–650 °C and 15.23–64.45 s. Then the model validation by using the experimental data from other conditions. The validation results showed that the kinetic model can predict the gas concentration with an acceptable deviation. Afterward, the indicators of carbon gasification efficiency and gas yield versus residence time are predicted. The results show that the required residence time for the complete gasification is varied from 214.2 to 2150.8 s when the temperature changes from 500 to 650 °C. Moreover, the reaction rate analysis result indicates that the two reactions contributed most to the hydrogen production are the forward water-gas shift and the reverse CO methanation reaction. Additionally, the sensitivity analysis result reveals that the hydrolysis reaction of diesel has a significant influence at the initial stage, while the CO and CO 2 methane reactions play a vital role at the late stage for gas production. [Display omitted] • A kinetic model with 13 reactions of SCWG of oil-containing wastewater is developed. • Residence time of 239.2 s for complete gasification under 650 °C is predicted. • Reaction rates for gases production and consumption are analyzed. • The hydrolysis reaction of diesel has a significant influence at the initial stage. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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