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Water gas shift (WGS) reaction commonly converts CO to CO 2 using H 2 O and produces H 2 and CO 2 in a catalytic fixed bed reactor. This study aims to develop a Cu/ZnO/ZSM-5 catalyst loaded in water gas shift reactor for converting typical synthesis gas produced from dry reforming of methane (DRM) at medium temperature shift (MTS, 200–350 oC) conditions and for preventing reverse reaction due to high feed concentrations of CO 2 and H 2. The Cu/ZnO/ZSM-5 catalyst was prepared by impregnation method with lower Cu metal loading of 5, 10, and 15 wt%, respectively, compared to commercial catalysts. The synthesized catalyst was characterized using XRF, XRD, SEM, H 2 -TPR, NH 3 -TPD, and TGA. The catalyst activity and stability for the WGS reaction were tested in the fixed bed reactor at atmospheric pressure and temperature of 325 °C. The experimental results show that CO conversion increases with increasing Cu loading. The 15 wt% Cu/ZnO/ZSM-5 catalyst showed the best results with a CO conversion of 35% and a yield of H 2 of 36% and showed good stability for 32 h. Based on the TGA, the 15 wt% Cu/ZnO/ZSM-5 catalyst forms a 0.04 g carbon/g catalyst, which is much lower when compared to commercial catalyst (0.105 g carbon/g catalyst). The relative activity of the synthesized catalyst indicates 2.4 times better when compared to commercial catalysts. High concentrations of H 2 and CO 2 in the feed may initiate side reactions, including reverse WGS, methanation, and carbon formation, which will decrease H 2 yield. • Cu/ZnO/ZSM-5 catalyst boosts CO conversion to 35% at 325 °C in WGS reaction. • 15 wt% Cu/ZnO/ZSM-5 achieves 36% H2 yield with 32-h stability in WGS. • Carbon formation is 0.04 g/g, lower than commercial catalyst's 0.105 g/g. [ABSTRACT FROM AUTHOR]

The concentration of hydrogen in oxygen (HTO) is a crucial factor in determining the load limit of alkaline water electrolysis (AWE) due to the risk of explosion with high HTO levels. In this study, we analysed the impact of circulating electrolytes, carrying dissolved gas, on HTO in a home-designed zero-gap alkaline water electrolysis system, operating at atmospheric pressure and constant temperature. By comparing the experimental results from mixed and separated cycles, we found that the amount of dissolved hydrogen in the electrolyte significantly contributes to HTO. We then developed a theoretical model to predict HTO values and experimentally confirmed a linear relationship between the HTO and the ratio of electrolyte circulation to gas production (Q L / Q O 2 ). Based on this evidence, we proposed a new electrolyte circulation control strategy that reduces the HTO value by as much as 63.56%. These findings could help overcome the load limit of alkaline water electrolysis systems, which is crucial for their large-scale application. [Display omitted] • Electrolyte circulation contributes significantly to HTO. • Circulating electrolytes carries dissolved hydrogen that increases HTO. • Optimization of electrolyte circulation helps to reduce HTO by up to 63.56%. [ABSTRACT FROM AUTHOR]

Smouldering has recently been developed as a cost effective and energy efficient technology for challenging wastes. These systems are often used to eliminate environmental liabilities, and only minimal work has explored their use for generating useful by-products. This study addressed this research gap and demonstrated that applied smouldering systems can be tuned to favour hydrogen production. Calcium oxide and steam were added to the smouldering system, which completely treated woody biomass and coal tar, while producing hydrogen. The maximum hydrogen concentration achieved in the smouldering system was 33.7%, resulting in a net energy positive syngas. Results suggest that both heterogenous gasification and the water gas shift were key mechanisms behind hydrogen formation. These results indicate that smouldering systems can be used as a new method to sustainably produce hydrogen-rich syngas from challenging wastes. [Display omitted] • Experimental study produced up to 34% H 2 from smouldering combustion. • Experiments used different fuels, porous media, steam, and CaO amendments. • New methodology to drive net-energy-positive H 2 -rich syngas from smouldering. • Optimum steam/carbon ratio was found to be between 2 and 3 to maximize H 2 yield. • Heterogenous gasification and the water gas shift were key H 2 production mechanisms. [ABSTRACT FROM AUTHOR]

Background: The facultatively anaerobic thermophile Parageobacillus thermoglucosidasius is able to produce hydrogen gas (H2) through the water–gas shift (WGS) reaction. To date this process has been evaluated under controlled conditions, with gas feedstocks comprising carbon monoxide and variable proportions of air, nitrogen and hydrogen. Ultimately, an economically viable hydrogenogenic system would make use of industrial waste/synthesis gases that contain high levels of carbon monoxide, but which may also contain contaminants such as H2, oxygen (O2) and other impurities, which may be toxic to P. thermoglucosidasius. Results: We evaluated the effects of synthesis gas (syngas) mimetic feedstocks on WGS reaction-driven H2 gas production by P. thermoglucosidasius DSM 6285 in small-scale fermentations. Improved H2 gas production yields and faster onset towards hydrogen production were observed when anaerobic synthetic syngas feedstocks were used, at the expense of biomass accumulation. Furthermore, as the WGS reaction is an anoxygenic process, we evaluated the influence of O2 perturbation on P. thermoglucosidasius hydrogenogenesis. O2 supplementation improved biomass accumulation, but reduced hydrogen yields in accordance with the level of oxygen supplied. However, H2 gas production was observed at low O2 levels. Supplementation also induced rapid acetate consumption, likely to sustain growth. Conclusion: The utilisation of anaerobic syngas mimetic gas feedstocks to produce H2 and the relative flexibility of the P. thermoglucosidasius WGS reaction system following O2 perturbation further supports its applicability towards more robust and continuous hydrogenogenic operation. [ABSTRACT FROM AUTHOR]

Through the actual production situation of the PSA unit in a large refinery's hydrogen production unit, it was found that the problems that occurred during the operation of the PSA unit were mainly concentrated in two aspects; Adsorbent crushing and program control valve failure. After analysis, it is believed that the main reasons for the crushing of adsorbent are the pressure difference and gas flow rate during the pressure equalization process, the influence of the adsorbent pressure network and pressure plate on the top of the adsorption tower, the presence of water in the feedstock gas, and the failure of the programmable valve, which mainly includes valve inspection alarm, electromagnetic valve failure, damage to the valve core sealing surface, leakage of the packing gland, cracking of the valve plate shaft sleeve, and breakage of the valve pin breakage, etc. Based on long-term practical experience, summarize and list the basis for judging faults, analyze the causes of various faults, and develop effective measures such as refining equipment installation inspections, strengthening daily maintenance, optimizing operating parameter settings, and upgrading relevant accessory materials. This can eliminate common faults in the PSA unit and ensure its long-term stable operation. [ABSTRACT FROM AUTHOR]

Plastic waste is being manufactured for the production of hydrogen. The amount of plastic waste collected annually is 189,953 tonnes from adjacent nations like Indonesia and Malaysia. Polyethylene (PE), Polypropylene (PP), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), and Polystyrene (PS) are the five most prevalent forms of plastic found in most waste. Pyrolysis, water gas shift and steam reforming reaction, and pressure swing adsorption are the three main phases utilized and studied. In this research, authors examines the energy consumption on every stage. The plastic waste can be utilized to manufacture many hydrocarbons using the pyrolysis reaction. For this process, fast pyrolysis is being used at a temperature of 500 °C. A neutralization process is also needed due to the presence of Hydrochloric acid from the pyrolysis reaction, with the addition of sodium hydroxide. This is being carried to prevent any damage to the reactor during the process. Secondly, the steam reforming process continues after the water gas shift reaction has produced steam and carbon monoxide, followed by carbon dioxide and hydrogen formation. Lastly, pressure swing adsorption is designed to extract H2S and CO2 from the water gas shift and steam reforming reaction for greater purity of hydrogen. From the simulation study, it is observed that using various types of plastic waste procured (total input of 20,000 kg per hour of plastics) from, Brunei Darussalam, Malaysia and Indonesia, can produce about 340,000 tons of Hydrogen per year. Additionally, the annual profit of the Hydrogen production is estimated to be between $ 271,158,100 and $ 358,480,200. As per the economic analysis, it can be said that its a good to start hydrogen production plant in these regions. [ABSTRACT FROM AUTHOR]

This research presents a simulated model of hydrogen generation through the application of the steam gasification process (SGP) for algae biomass coupled with the water-gas shift (WGS) reaction. A non-stoichiometric equilibrium-based model is constructed in Aspen Plus and validated against available experimental results in the literature. Four types of algae, namely Spirulina , Chlorella vulgaris , Spirogyra , and Rhizoclonium sp., are utilized as biomass feedstocks. The impact of operating conditions, such as gasifier temperature and the steam-to-biomass ratio (SBR), on the composition of the product gas is investigated. Exergy efficiency and cold gas efficiency (CGE) for each type of algae are calculated and examined within the SBR range of 0.2–1.2 and the gasifier temperature range of 650 °C–1050 °C. The results indicate that the maximum H 2 concentration is attained at the highest SBR while there exists an optimum value for the gasifier temperature. Exergy efficiency demonstrates an enhancement with an increase in gasification temperature and SBR. Among the algae types, Spirulina exhibits the highest exergy efficiency at a temperature of 1050 °C (61.3 %), whereas Spirogyra demonstrates the lowest exergy efficiency at the same temperature (35 %). Furthermore, at an SBR of 0.2, Rhizoclonium sp. demonstrates the highest exergy efficiency (41.8 %), and Spirogyra exhibits the lowest exergy efficiency (27.9 %). The findings also reveal that an increase in SBR leads to a decrease in CGE, whereas an increase in gasifier temperature improves the CGE. The influence of the WGS reaction on CGE and exergy efficiency is investigated. The results indicate that the WGS reaction contributes to an improvement in exergy efficiency, but it has a negative effect on CGE. [Display omitted] • H 2 production via steam gasification of algae biomass is evaluated. • Process performance is considered in terms of exergy efficiency and CGE. • There is an optimum value for gasifier temperature to maximize H 2 production. • The exergy efficiency improved with increasing gasification temperature and SBR. • Spirulina and spirogyra algae had the highest and lowest CGE. [ABSTRACT FROM AUTHOR]

The catalytic gasification of sewage sludge was explored using different catalyst particle sizes, bed temperatures, and gasifying agents. Activated carbon and sawdust biochar were used as catalysts in this study. The effects of the porosity of activated carbon on tar adsorption and cracking, and biochar containing alkali and alkaline earth metallic species (AAEMs), which can enhance gasification reactions, were investigated under different conditions. A catalyst bed temperature of 800 °C and particle size of 0.5–1.7 mm showed optimum conditions for increasing H 2 and CO content and decrease CO 2 fraction; however, a higher solid residue (∼38 wt%) was also observed due to the high ash content in sewage sludge. Furthermore, the introduction of steam had a positive effect on the H 2 increment, owing to the presence of inherent AAEMs in the biochar, promoting water gas shift and hydrocarbon steam reforming reactions. The results of this study provide effective measures for using activated carbon and affordable biochar to enhance H 2 production with a parametric effect on the catalyst bed. [Display omitted] • Sewage Sludge gasification was performed over activated carbon and biochar. • Effect of catalysts bed particle size and temperature was investigated. • Particle size of 0.5–1.7 mm and temperature of 800 °C was considered optimum for H 2. • Biochar showed significant water gas shift activity compared to activated carbon. • The presence of AAEMs in biochar can enhance H 2 generation. [ABSTRACT FROM AUTHOR]

The thermodynamic simulation analysis of carbon monoxide water gas shift in rich hydrogen was researched by using the method of Gibbs free energy minimization with Aspen plus software. For the purpose of purifying trace amount of CO in hydrogen, two raw gas compositions, 1%CO–99%H 2 and 1%CO–24%CO 2 –75%H 2 , were purposely selected, and the influences of water to gas molar ratio (1–7) and transformation temperature (40–280 °C) were investigated. The results showed similar variation law as compared with the water gas shift of a pure CO gas. When the transformation temperature increased, the chemical equilibrium shifted toward the reverse direction, resulting in decreased CO equilibrium conversion; when the water to gas molar ratio increased, the CO conversion increased. The results also showed that CO 2 had great negative effects on CO conversion compared with H 2. For the CO/H 2 feed gas, it was concluded that it was possible to reduce the 1% CO content to 100 ppm at 120 °C with the use of the best low-temperature catalyst reported in literature. If we want to further reduce the trace amount of CO in hydrogen to 10 ppm, it is necessary to develop ultra-low temperature catalysts that are highly active below 70 °C. • Simulation of CO water gas shift reaction in excess H 2 and H 2 /CO 2. • CO 2 has a great influence on CO conversion compared to H 2. • 1%CO in H 2 reduced to 100 ppm with the available catalyst at 120 °C. • To reduce CO to 10 ppm, it is necessary to develop catalysts below 70 °C. [ABSTRACT FROM AUTHOR]

Methane reforming and gasification processes are valuable pathways toward hydrogen production, and currently they represent nearly 79% of the worldwide hydrogen production market share. Chemical looping-water gas shift (CL-WGS) is a promising downstream process that can be integrated with reforming and gasification reactors and utilizes redox active metal oxides as oxygen exchange materials to produce separate streams of H 2 and CO 2. Thus, this technology can enable the production of high-purity hydrogen coupled with carbon capture without the need for an additional CO 2 separation system. Although a number of redox-active metal oxides have been proposed in the literature as viable candidates for CL-WGS, the majority are based on stoichiometric metal oxides. However, non-stoichiometric oxides, which have the benefit of stability, rapid kinetics, and thermodynamic tunability, have only been proposed a handful of times. And of the prior proposed non-stoichiometric materials, none of the so called "water splitting" redox materials of the solar thermochemical H 2 O splitting (STCH) fields have been discussed for CL-WGS applications, despite their potentially favorable thermodynamic properties. In this research, we have identified 13 potential oxygen carrier materials and screened these for CL-WGS viability based on a simplified closed-system thermodynamic analysis. Ceria (CeO 2-δ), CZO20 (Ce 0.8 Zr 0.2 O 2-δ), and LSMA4060 (La 0.6 Sr 0.4 Mn 0.4 Al 0.6 O 3-δ) are identified to have the most suitable properties in terms of operating temperatures, specific H 2 yields, and conversions of syngas, during reduction, and steam, during oxidation. Results show that CZO20 and LSMA4060 have especially excellent reduction and oxidation extents at relatively low operating temperatures. For example, CZO20 and LSMA4060 have 85% syngas and steam conversions when cycled between 485-912 and 100–635 °C, respectively. Results show that only CZO20 is viable for isothermal operation, but higher temperatures are required; at 1023 °C, syngas and steam conversions are 80 and 12%. • Screening of 13 candidate oxygen carriers for chemical looping water gas shift reactor. • A thermodynamic analysis is implemented to compare the candidate materials. • The comparison based on operating temperatures, H 2 yields, and conversions of syngas and steam. • La 0.6 Sr 0.4 Mn 0.4 Al 0.6 O 3-δ shows highest conversions (i.e., >85%) at low T (e.g., 100–635 °C). • Ce 0.8 Zr 0.2 O 2-δ shows highest conversions (i.e., >85%) at moderate T (e.g., 485–912 °C). [ABSTRACT FROM AUTHOR]

Some methods were considered to remove tritium-containing hydrogen compounds from various gas flows from scientific and production facilities in the nuclear and thermonuclear power industry. The possibilities of tritium removal from a gas flow in the form of hydrogen were analyzed, and it was concluded that these methods can be applied at low flow rates of the gas being purified. At high gas flow rates, the main detritiation methods are adsorption and water phase isotope exchange. Both these methods include the preliminary catalytic oxidation of tritium-containing molecules to water with the further removal of tritiated water from the gas. The main technological parameters of these methods were compared, and it was inferred that phase isotope exchange has great advantages. [ABSTRACT FROM AUTHOR]

Some major drawbacks encountered in the synthesis of copper-ceria (Cu-CeO2)-based Water Gas Shift (WGS) catalyst via the conventional Impregnation (IMP) method are aggregate formation and nanoparticles' instability. These lead to the poor interaction between Copper and Ceria, thereby impeding the catalytic activity with the inefficient utilization of active sites. To overcome these drawbacks, in this study, we described the synthesis of the Cu-CeO2 catalyst via the Reverse Microemulsion (RME) method with the help of the organic surfactant. This development of insights and strategies resulted in the preparation of porous particles with uniform size distribution and improved interaction within the composites, which were evident through XRD, XPS, BET Surface area, TPR, TEM and SEM analysis results. Remarkably, the optimum 20% Cu-CeO2 catalyst prepared by RME method was found to have superior Water Gas Shift (WGS) catalytic activity than the conventionally Impregnated catalyst when their CO conversion efficiencies were tested in WGS reaction at different feed gas compositions with and without CO2. Moreover, the 20% Cu-CeO2 sample prepared by RME method exhibited sustained catalytic activity throughout the entire 48 h period without any signs of deactivation. This observation highlights RME method as the potential pathway for developing more effective nanoparticle catalysts for hydrogen production, contributing to the growing demand for clean and sustainable energy sources. [ABSTRACT FROM AUTHOR]

Hydrogen is mainly produced by steam reforming of fossil fuels. Thus, research has been continuously conducted to produce hydrogen by replacing fossil fuels. Among various alternative resources, waste is attracting attention as it can produce hydrogen while reducing the amount of landfill and incineration. In order to produce hydrogen from waste, the water–gas shift reaction is one of the essential processes. However, syngas obtained by gasifying waste has a higher CO concentration than syngas produced by steam reforming of fossil fuels, and therefore, it is essential to develop a suitable catalyst. Research on developing a catalyst for producing hydrogen from waste has been conducted for the past decade. This study introduces various catalysts developed and provides basic knowledge necessary for the rational design of catalysts for producing hydrogen from waste-derived syngas. [ABSTRACT FROM AUTHOR]

This work presents for the first time an integrated hydrogen generation system with storage based on aluminum waste from soda cans to supply hydrogen on-demand to a PEM (proton exchange membrane)-type fuel cell for reliable electricity generation. The raw material that feeds the hydrogen generator consists of distilled water, aluminum from soda cans and sodium hydroxide to remove the oxide layer that passivates the aluminum, a technique known as alkaline activation. The design of the generator was done based on the analysis of the mass and energy balance and its experimental verification. The stainless-steel prototype consisted of a vessel with a capacity of 2.1 L batch reactor, which delivers the gas produced to a column of water to scrub the gas. The three components function as a temporary gas storage system while the fuel is delivered at a regulated pressure. The NaOH container has a maximum storage capacity of 0.45 L, enough for 21 g of aluminum to react and produce 25.7 L (at 0 °C and 105 Pa) of hydrogen; the reaction yield in the generator was 97%. Through the evaluation of the electrical performance at a home-made 9 cm2 PEMFC and extrapolation to 45 W, it was calculated that the generator can supply H2 to the cell for 53 min at that power. [ABSTRACT FROM AUTHOR]

The water–gas shift (WGS) reaction is an important process in the hydrogen industry, and its catalysts are of vital importance for this process. However, it is still a great challenge to develop catalysts with both high activity and high stability. Herein, a series of high-purity Cu-Mn-Al hydrotalcites with high Cu content have been prepared, and the WGS performance of the Cu-Mn-Al catalysts derived from these hydrotalcites have been studied. The results show that the Cu-Mn-Al catalysts have both outstanding catalytic activity and excellent stability. The optimized Cu-Mn-Al catalyst has displayed a superior reaction rate of 42.6 μ mol CO − 1 ⋅ g cat − 1 ⋅ s − 1 , while the CO conversion was as high as 96.1% simultaneously. The outstanding catalytic activities of the Cu-Mn-Al catalysts could be ascribed to the enriched interfaces between Cu-containing particles and manganese oxide particles, and/or abundant oxygen vacancies. The excellent catalytic stability of the Cu-Mn-Al catalysts may be benefitting from the low valence state of the manganese of manganese oxides, because the low valence manganese oxides have good anti-sintering properties and can stabilize oxygen vacancies. This study provides an example for the construction of high-performance catalysts by using two-dimensional hydrotalcite materials as precursors. [ABSTRACT FROM AUTHOR]

When storing gas in a salt cavern, it occupies most of the excavated volume, but the lower part of the cavern inevitably contains residual brine, in contact with the gas. The design of hydrogen and compressed air storage in salt caverns requires to have a thermodynamic model able to accurately predict both phase properties such as densities, and phase equilibrium (gas solubility and water content of the vapour phase). This work proposes a parameterization of the e-PPC-SAFT equation of state in this context. Experimental data of pure components and mixtures of light gas + pure water and light gas + salted water are reviewed and used to fit pure component parameters for hydrogen, nitrogen, oxygen, and the brine, and binary interaction parameters between H2, O2, N2 + water and H2, O2, N2 + ions (Na+ and Cl−), for temperature ranging from 273 to 473 K and salinities up to NaCl saturation (6 mol/kg). The model developed delivers good accuracy in reproducing data: the average deviation between experiments and calculated data is between 3% and 9% for gas solubility in saturated brine. More interestingly, the model has been validated on its capability to predict data not included in the parameterization database, including the composition of the vapor phase, and its extension to a mixture, such as air. Finally, it has been used in a case study of Compressed Air Energy Storage (CAES) to evaluate the water content of the gas produced during injection-withdrawing cycles. [ABSTRACT FROM AUTHOR]

In the present article, a series of coupled computational physics - fluid dynamics models were developed aiming at assessing the feasibility of photothermal synthetic fuel production from biogas (biomethane) and steam blends using plasmonic nanostructure Ag/TiO 2 substrate (each, 0.1 μm in thickness) inside a thermal, momentum and mass transport boundary layer in a microreactor. A chain of partial and complete biogas reforming and water-gas shift reactions were modelled as the dominant chemical reactions responsible for synthetic fuel production from biomethane. Using equilibrium analysis, plausible thermodynamic operating conditions were identified and applied to the computational models. The effect of light wavelength (λ) on the reaction rate, chemical conversion extent, syngas quality, exergy partitioned in synthetic fuel, and composition of gas products were investigated. The results showed that the performance of the microreactor is wavelength-dependent. It was found that the highest production rate for the synthetic fuel was achieved at 580 nm < λ < 620 nm. Within the same wavelength range, the chemical conversion of biomethane to synthetic fuel reached 85% at steam to methane ratio of 3 and the synthetic fuel quality was >2.05, which is suitable for a Fischer-Tropsch process. It was also identified that the syngas quality of the synthetic fuel can be regulated by adjusting the wavelength of the light. The exposure time was also identified to be a critical parameter affecting the performance of the microreactor. For an exposure duration of up to 10 ns, high quality of synthetic fuel >2.05 can be achieved within the optimum wavelength range of 580 nm < λ < 620 nm. • Syngas production via plasmonic 1 μm microreactor was numerically investigated. • Computational physics and computational fluid dynamics modelling were utilised. • Effect of light wavelength on conversion and syngas quality was investigated. • Conversion of 85% at wavelength 580 < 620-nm was reported. • Exposure time was a key operating parameter affecting quality of syngas. [ABSTRACT FROM AUTHOR]

Despite the potential of hydrogen (H2) storage in liquid organic carriers to achieve carbon neutrality, the energy required for H2 release and the cost of catalyst recycling have hindered its large‐scale adoption. In response, a photo flow reactor packed with rhodium (Rh)/titania (TiO2) photocatalyst was reported for the continuous and selective acceptorless dehydrogenation of 1,2,3,4‐tetrahydroquinoline to H2 gas and quinoline under visible light irradiation at room temperature. The tradeoff between the reactor pressure drop and its photocatalytic surface area was resolved by selective in‐situ photodeposition of Rh in the photo flow reactor post‐packing on the outer surface of the TiO2 microparticles available to photon flux, thereby reducing the optimal Rh loading by 10 times compared to a batch reactor, while facilitating catalyst reuse and regeneration. An example of using quinoline as a hydrogen acceptor to lower the energy of the hydrogen production step was demonstrated via the water‐gas shift reaction. [ABSTRACT FROM AUTHOR]

Dimethyl ether (DME) is an emerging alternative to traditional diesel and LPG as a power-to-X product. This study employs kinetic models to simulate potential DME production routes, assessing key technical and economic performance indicators for comparison. Aspen Plus, a commercial process flowsheet simulation tool, is used alongside Pinch methodology for heat integration. Four production routes are examined: two direct, converting feed gas directly to DME, and two indirect, involving methanol as an intermediate step. For one case in each, CO 2 is initially converted to CO via the reverse water gas shift process (rWGS). Post heat integration, all routes exhibit higher cooling demand, with significant energy savings, notably in the indirect pathways. Indirect routes achieve power-to-fuel efficiencies of up to 39.6%, considering electrolysis and carbon capture. Direct routes excel in carbon conversion efficiencies, reaching 92.6%. Economically, indirect routes have higher upfront costs but lower operational expenses due to better energy efficiencies. Direct CO 2 conversion yields the lowest levelized manufacturing costs at 2.45 €/kg, closely followed by the indirect route with rWGS. Further research is needed to enhance kinetic models and reduce simulation result uncertainty for direct conversion. • Comparison of four potential routes to produce dimethyl ether from hydrogen and carbon dioxide. • Detailed process simulation of each considered production pathway. • Evaluation of technical and economical key performance indicators for each process route. • Identification of remaining research questions regarding the renewable production of dimethyl ether. [Display omitted] [ABSTRACT FROM AUTHOR]

The WGS reaction is an exothermic reaction between carbon monoxide and steam to form carbon dioxide and hydrogen. This reaction, which has been used industrially for more than 100 years, has recently received a great deal of attention from researchers as one of the ways to produce environmentally acceptable hydrogen from fossil fuels in large quantities. For the application of this reaction on an industrial scale, the key is choosing the optimal catalysts that can ensure high CO conversion and have a long lifetime under industrial conditions. Therefore, new types of catalysts are being developed that meet these requirements better than the Fe- and Cu-based catalysts commonly used in the past. The WGSR on a commercial nickel-based catalyst and a laboratory-prepared copper- and cobalt-based catalyst was tested in a laboratory apparatus set up at the University of Chemistry and Technology Prague. The best performance of the laboratory-prepared catalyst was observed for the catalyst with a Cu content of 14.8 wt% and activated in a hydrogen atmosphere. The laboratory-prepared Co-based catalyst showed good WGSR activity in the temperature range of 200–450 °C, although this was always inferior to that of the Cu-based catalyst. When subjected to the feed gas containing 0.4 mole% H2S, the Co-based catalyst showed good resistance to sulphur poisoning. Therefore, Co-based catalysts can be considered good sulphur-tolerant intermediate temperature WGSR catalysts. [ABSTRACT FROM AUTHOR]

Summary: A comprehensive model is developed to predict and optimize the hydrogen production via integrated configuration of steam gasification process of biomass and water‐gas shift reaction by taking advantage of the ASPEN plus software and sensitivity analysis techniques. The steam gasification process of three different generations of biomass, including corn cob as the first generation, wood residue and rice husk as second generation, and Spirulina algae as the third, are investigated and evaluated to achieve maximum hydrogen production. This model is successfully validated with experimental data reported in the literature about steam gasification of rice husk in the fluidized bed reactor. The impact of main operating parameters is considered in terms of products composition, hydrogen yield, CO conversion, H2/CO ratio in the gas products stream, and cold gas efficiency (CGE). The results indicated that the maximum hydrogen concentration is achieved at the highest steam to biomass (S/B) ratio in the gasifier and water‐gas shift (WGS) reactor and at the lowest WGS reaction temperature, whereas there is an optimum value about the gasification temperature. The highest CO conversion and H2/CO molar ratio belong to rice husk biomass at all considered range of temperature, whereas they are almost the same for wood residue and Spirulina. The predicted results confirmed that CGE of all feedstocks improves with increasing gasification temperatures and S/B ratio. The steam gasification performance of different feedstocks at 750°C is ranked as wood residue (83.56%) > spirulina (83.47%) > corn cob (74.94%) > rice husk (69.86%). The presented configuration can be applied as a novel approach for process evaluation and optimization through the downdraft biomass gasification integrated with water‐gas shift reaction to intensify the hydrogen production. [ABSTRACT FROM AUTHOR]

• Novel concept of thermally coupled catalytic hydrogen combustion-reverse water gas shift reactor is reported. • Concept feasibility was demonstrated via numerical simulations of transient 2D model. • Hot spot location, which is crucial for reactor performance, can be controlled by feed temperature and space velocity. • Reactor model predicted 100% catalytic H2 combustion conversion and 80% CO2 conversion. Thermally coupled catalytic hydrogen combustion-reverse water gas shift reactor for CO 2 conversion to synthesis gas was designed and numerically analyzed using a 2D model with a shell-and-tube configuration. A transient, pseudo-homogeneous mathematical model was formulated accounting for axial and radial heat dispersion and using experimentally obtained reaction kinetic parameters. Transient reactor behavior was studied to analyze the dynamic behaviour. Steady-state reactor performance was analyzed in terms of temperature and reactant/product distribution, as well as output parameters of practical importance, namely maximum and outlet reactor temperatures, and outlet conversions. Numerical simulations demonstrate the feasibility of the suggested reactor concept and providing insights into thermal management, including the formation of hot spots, appearance of temperature fronts, and the importance of thermal insulation. The model predicted the possibility of 100 % catalytic H 2 combustion conversion and 80 % CO 2 conversion, with the reactor temperature of ca. 900 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pt doping produced a synergistic effect that promoted the reduction of Pt and Co. • Activity of bimetallic Pt-Co catalysts in glycerol APR was stable over 100 h TOS. • WGS activity of bimetallic assays was higher than monometallic counterparts. • Improved stability was related to restrained coke formation. • Co oxidation and leaching are the main drawbacks of Pt-Co bimetallic catalysts. Pt/CoAl 2 O 4 catalysts with small amounts of Pt (0.3 and 1 wt.%) were prepared by wet impregnation of platinum on cobalt aluminate (mole ratio Co/Al = 0.625). These catalysts were compared with monometallic Pt/alumina and cobalt aluminate counterparts. The physicochemical characteristics of the obtained materials were thoroughly analysed. The catalytic performance of the prepared assays was investigated in the Aqueous-Phase Reforming (APR) of glycerol for up to 100 h TOS, and in liquid phase Water-Gas Shift (WGS). It was concluded that the addition of Pt to cobalt aluminate resulted in a synergistic effect that promoted the reduction of both Pt and Co species, as well as cobalt dispersion, what increased the amount of exposed metallic sites. These effects were, however, sensitive to the amount of Pt loaded. The glycerol APR activity of bimetallic catalysts was very stable over 100 h TOS with conversion values above 99 %. Conversion to gas was also above 95 % during the whole operation. Contrarily, the counterpart monometallic catalysts suffered noticeable deactivation at above 70 h TOS. Also, WGS activity of bimetallic assays was higher than the monometallic counterparts. Addition of Pt to cobalt aluminate lowered selectivity to hydrogen, due to a higher CO hydrogenation activity. Examination of the spent catalysts showed better textural stability of the bimetallic samples, as well as much lesser formation of carbonaceous surface deposits. Nevertheless, oxidation and leaching of cobalt remains as the main drawback of bimetallic catalysts to be used in APR. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) fuel synthesis depends on the intermittent solar intensity of the diurnal cycle and ceases at night. Here, an integrated device that does not only possess PEC water splitting functionality, but also operates as an electrolyzer in the nocturnal period to improve the overall capacity factor is described. The bifunctional system is based on an "artificial leaf" tandem PEC architecture that contains an inverse‐structure lead halide perovskite protected by a graphite epoxy/parylene‐C coating (conferring 96 h stability of operation in water), and a porous BiVO4 semiconductor. The light‐absorbers are interfaced with a H2 evolution catalyst (Pt) and a Co‐based water oxidation catalyst, respectively, which can also be directly driven by electricity. Thus, the device can operate in PEC mode during irradiation and switch to an electricity‐powered mode in the dark through bypassing of the semiconductor configuration. The bifunctional perovskite‐BiVO4 tandem provides a solar‐to‐hydrogen efficiency of 1.3% under simulated solar irradiation and an onset for water electrolysis at 1.8 V. The compact design and low cost of the proposed device may provide an advantage over other technologies for round‐the‐clock fuel production. [ABSTRACT FROM AUTHOR]

Inadequate management of swine manure can lead to contamination of watercourses, groundwater, soil, and air, representing a risk to the sustainability and expansion of pig farming as an economic activity. The aim of this study was to evaluate the potential of this waste for the production of hydrogen from swine manure biogas through steam reforming and water gas shift processes. In this study, calculations of ecological, exergetic and economic efficiencies were carried out. The ecological efficiency, pollution indicator and energy efficiency of the process were, respectively, 93.73%, 19.15 and 79.06%, showing the viability from an ecological standpoint. This is an 8-year plant payback with a hydrogen production cost of $0.14/kWh, in a production scenario of 8760 h/year, showing an exergetic efficiency of 76%. The results from these analyses demonstrates that this type of hydrogen production is an attractive economic route. The results from these analyses have shown that this hydrogen production technology has great economic potential and presents high exegetic yield. • The hydrogen cost is 0.14 US$/kWh. • The production of hydrogen by cassava wastewater provides economic feasibility. • The exergetic efficiency of the plant was 93.73%. • The pollution indicator of the plant was 19.57 kg CO2e /kg H2. • The ecological efficiency of the plant was 93.73%. [ABSTRACT FROM AUTHOR]

Summary: To increase the hydrogen (H2) concentration in bio‐syngas containing carbon dioxide(CO2), water‐gas shift reaction (WGSR) is widely used. In this study, the effects of CO2 concentration on the WGSR and unwanted side reactions were investigated by varying the operating parameters, such as the steam/carbon monoxide (CO) ratio, reaction temperature, and the gas‐hourly space velocity (GHSV). Based on the obtained results, CO conversion and H2 yield decreased with increasing CO2 concentration, especially when the steam/CO ratio was lower than 3. This implies that to minimize the negative effect of CO2 on WGSR, the steam/CO ratio should be 3 or higher. For any CO2 concentration, the highest CO conversion and H2 yield were obtained at a reaction temperature of 400°C. Therefore, the temperature should be precisely controlled at 400°C. As GHSV decreased, the CO conversion approached equilibrium with any CO2 concentration; however, the H2 yield remained unchanged. [ABSTRACT FROM AUTHOR]

Existing literature data have been used to model the steam reforming of ethanol on catalytic honeycombs coated with Rh-Pd/CeO 2 , which have shown an excellent performance and robustness for the production of hydrogen under realistic conditions. In this article, a fully 3D non-isothermal model is presented, where the reactions of ethanol decomposition, water gas shift, and methane steam reforming have been modelled under different operational pressures (1–10 bar) and temperatures (500–1200 K) at a steam to carbon ratio of S/C = 3 and a space time of W/F between 2·10−3 and 3 kg h L liq −1. According to the modelling results, a maximum hydrogen yield of 80% is achieved at a working temperature of 1150 K and a pressure of 4 bar at S/C = 3. • Ethanol steam reforming has been modelled with a 3D non-isothermal model. • EtOH decomposition, water gas shift and CH 4 steam reforming have been considered. • Honeycombs loaded with Rh-Pd/CeO 2 catalyst have been modelled at S/C = 3. • A maximum H 2 yield of 80% is achieved at 1150 K and 4 bar. [ABSTRACT FROM AUTHOR]

In this study, gasification performance and importance of hydrogen production using waste of a tea factory were evaluated. A mathematical model was developed for the gasification system, which includes a water gas shift reactor used for hydrogen purification. The gasifier temperature was 877 °C for the developed model. The model has been validated against experimental data from an 80 kW thcylindrical downdraft gasifier, given in the literature for syngas composition for three different air-to-fuel ratios. With the developed model, hydrogen production from tea wastes was achieved to yield a higher level by additionally using a water gas shift reactor. Tea waste (1000 kg) was gasified and after the hydrogen purification process, a total of 4.1 kmol hydrogen was achieved, whereas the amount would be 2.8 kmol gas hydrogen if a normal gasification method were used. The validity of the developed model was verified by comparing the experimental results obtained from the literature with the results of the model under the same conditions. After verification of the developed model, the effect of the moisture content of the biomass and the air/fuel ratio on the composition of the product gas were investigated. These investigations were also confirmed by experimental data. The results show that it is important to convert biomass waste into a clean energy source of hydrogen to minimize its environmental impact. [ABSTRACT FROM AUTHOR]

Fischer‐Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe‐Mn‐K/MgO catalyst, a parameter screening and long‐term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water‐gas shift reaction and results in lower yields of hydrocarbons. [ABSTRACT FROM AUTHOR]

The hydroformylation of olefins is one of the most important homogeneously catalyzed industrial reactions for aldehyde synthesis. Various ligands can be used to obtain the desired linear aldehydes in the hydroformylation of aliphatic olefins. However, in the hydroformylation of aromatic substrates, branched aldehydes are formed preferentially with common ligands. In this study, a novel approach to selectively obtain linear aldehydes in the hydroformylation of styrene and its derivatives was developed by coupling with a water–gas shift reaction on a Rh single‐atom catalyst without the use of ligands. Detailed studies revealed that the hydrogen generated in situ from the water–gas shift is critical for the highly regioselective formation of linear products. The coupling of a traditional homogeneous catalytic process with a heterogeneous catalytic reaction to tune product selectivity may provide a new avenue for the heterogenization of homogenous catalytic processes. [ABSTRACT FROM AUTHOR]

Pd-based membranes prepared by pore-plating technique have been investigated for the first time under fluidization conditions. A palladium thickness around 20 μm was achieved onto an oxidized porous stainless steel support. The stability of the membranes has been assessed for more than 1300 h in gas separation mode (no catalyst) and other additional 200 h to continuous fluidization conditions. Permeances in the order of 5·10−7 mol s−1 m−2 Pa−1 have been obtained for temperatures in a range between 375 and 500 °C. During fluidization, a small decrease in permeance is observed, as consequence of the increased external (bed-to-wall) mass transfer resistances. Moreover, water gas shift (WGS) reaction cases have been carried out in a fluidized bed membrane reactor. It has been confirmed that the selective H 2 separation through the membranes resulted in CO conversions beyond the thermodynamic equilibrium (of conventional systems), showing the benefits of membrane reactors in chemical conversions. Image 1 • Novel Pd membranes prepared by pore-plate techniques are presented. • These membranes are tested under fluidizitation conditions for the first time. • Stability of these membranes is assessed for 1500 h in empty reactors. • CO conversion in the FBMR is above the one obtained in conventional reactors. [ABSTRACT FROM AUTHOR]

The push to control the greenhouse gas emissions is motivated by environmental regulations. For the aim to be achieved, the suggestion of eliminating or at least reducing gas flaring is currently taken under environment. In this regard, a new configuration for flare gas treatment is proposed in this study. This configuration is aimed to collect H 2 and CO 2 from flare gas, simultaneously. The collected components would be sent to the methanol synthesis reactor in the upstream section. The proposed configuration is made up of a multi-step membrane-assisted separation unit. In order to clarify what lies behind the idea, we proposed a mathematical formulation which is composed of conservation equations and kinetic rate equations is developed. H 2 and CO 2 elimination in the first step followed by a membrane-assisted water gas shift reactor for catalytic CO conversion and H 2 recovery in tandem, and removing the remaining CO 2 in the supplementary step is investigated numerically. The collected H 2 /CO 2 mixture is aimed to recover into the upstream methanol synthesis reactor. The obtained results reveal that by utilizing such a strategy, about 2500 kmol/day CO 2 (almost 98% of total input) is eliminated from the flare gas stream. Moreover, by considering the converted CO, about 4050 kmol/day CO 2 is recovered to the methanol reactor. As a whole, 0.68% enhancement in the methanol generation and the reduction of about 4050 kmol/day flare gas pollutants are achieved in tandem when 98% N 2 and 92.9% CH 4 is separated the from purge gas. Image 1 • Investigation of hydrogen and carbon dioxide recovery in a methanol plant. • Proposing a three-step membrane-based separation process. • Developing a mathematical model for the process. • Increasing methanol production inside decreasing carbon oxides release. [ABSTRACT FROM AUTHOR]

[Display omitted] • Process modelling of H 2 production through the BECCS approach. • Optimisation of steam-assisted gasification through kinetic-based modelling. • A hydrogen yield of 81.47 gH 2 /kg dry biomass has been estimated. • The overall energy efficiency of the system is 49.6%. • The emission factor is estimated at −1.38 kgCO 2 -eq/kg biomass. Hydrogen production through biomass gasification coupled with carbon capture has the potential to be a net negative emission process. Among the different designs of biomass gasifiers, the two-stage fixed bed gasifier has proved its ability to produce high quality syngas with minimum tar content at an industrial scale. However, it has not been investigated for hydrogen production. Hence, the current study is the first attempt to assess, through process modelling, the technical feasibility of hydrogen production in a 10 MW th two-stage gasification system using wood chips as feedstock. Mass and energy balances have been established in the Aspen Plus and MATLAB software. In contrast to most models in the literature, which were based on the equilibrium approach, the proposed system utilizes reliable kinetic models for the gasifier operation and the main downstream processes. An extensive validation of the gasifier kinetic model has been carried out and then a sensitivity analysis, which has revealed that the optimum steam-to-biomass ration (SBR) is 0.8 and 1.2 for the air-steam and the oxy-steam gasification systems, respectively. Further, the optimum steam-to-CO ratio (S/CO) for the water gas shift reactors (WGSRs) is 4, under which an overall 82.9% conversion of CO has been achieved. The results show that the 10 MW th two-stage gasifier can attain a specific hydrogen yield of 81.47 gH 2 /kg dry biomass. Based on the carbon footprint assessment, the process is net negative with an emission factor of −1.38 kgCO 2 -eq/kg biomass. Further, heat integration has also been conducted and it was found that the energy conversion efficiency of the whole system is 49.6%. This study is important since it provides a reliable data source for biomass-based hydrogen production through gasification in a commercial two-stage gasifier that can dictate operational strategies of pilot and demo plants. [ABSTRACT FROM AUTHOR]

Herein, (VO)2P2O7 nanosheets function as a highly-active electrocatalyst for the hydrogen evolution reaction with an ultralow overpotential of 30 mV at 10 mA cm−2 in basic media, being close to Pt/C. Furthermore, as a bifunctional electrocatalyst, (VO)2P2O7 not only exhibits high activity but also good stability for overall water splitting. [ABSTRACT FROM AUTHOR]

Polygeneration systems, designed for providing multiple energy services like hydrogen, heat and electricity, represent a possible solution for the transition to sustainable low-carbon energy systems, thanks to a substantial increase in the overall efficiency. A further step to reach zero-carbon energy systems can be done by using renewables as primary sources. In this study a biogas-based polygeneration system for the combined hydrogen, heat and electricity production is designed and analyzed from energy and economic points of view. The system consists of four sections: a biogas processing unit consisting in an autothermal reactor and a water gas shift reactor, an SOFC power unit, a hydrogen separation unit and a hydrogen compression/storage unit. The syngas generated in the autothermal reforming reactor is split in two fluxes: the first one is sent to the SOFC power unit for generating electricity and heat, the second one is sent to the water gas shift reactor to increase the hydrogen content. The hydrogen rich gas exiting the shifter, purified in the hydrogen separation unit (hydrogen quality is equal to 99.995%), is then compressed up to 820 bars and stored. The system behavior and the energy performances have been investigated by using the numerical simulation based on thermo-electrochemical models. Four operating conditions, related to different SOFC loads (from 30% to 100%), have been analyzed. The evaluated overall efficiencies range from 68.5% to 72.3% and the energy saving, calculated with respect to the separate production of hydrogen, heat and electricity, ranges from about 8% to 26%. The economic assessment, carried out by estimating the total capital investment and the plant profitability, has been performed by analyzing different management strategies (Base Load, Peaker, Ancillary Service and Mobility) and accounting for different technological development levels and market scenarios. Results show that the hydrogen production is the main contributor to the system economic sustainability thanks to the highest prices of hydrogen with respect to the electricity ones. • A techno-economic analysis of a biofuel-based Multi-Energy System (MES) is proposed. • Numerical modeling based on thermo-electrochemical models has been applied. • The polygeneration of electricity, heat and hydrogen has been studied. • Economic indicators have been calculated for estimating the plant profitability. • The MES economic sustainability is mainly due to the hydrogen production revenues. [ABSTRACT FROM AUTHOR]

In this study, co-pyrolysis of Xilinhot lignite (XL) and rice husk (RH) was carried out in an aluminum retort to investigate potential interaction mechanism by analyzing the product distribution and hydrogen transfer route. Results indicate that co-pyrolysis yields more water and less tar. This may be related to the hydrogen transfer route during co-pyrolysis process. Hydrogen free radicals prefer combining with small molecular free radicals to produce water and gas rather than combining with medium and large molecular free radicals to produce tar and char. The addition of RH induces the polycondensation reactions to form more condensed char, leading to a higher C/H atomic ratio of char. 1H NMR shows that the tar molecules from co-pyrolysis are with shorter side-chains, which may be because that more methoxyl free radicals from RH transfer into tar than individual pyrolysis, which can be confirmed by the higher content of methoxy phenols in co-pyrolysis tar than expected (from GC/MS analysis). Besides, the alkali and alkaline earth metals (AAEMs) in RH intensify not only the second cracking of tar from RH but also that from XL, leading to hydrogen transfer from tar to gas. • There are positive and negative synergies on water and tar formation, respectively. • H free radical prefers to combine with small free radicals rather than large ones. • AAEMs in RH intensify not only the cracking of tar from RH but also that from XL. • RH induces the polycondensation reactions to form more condensed char. [ABSTRACT FROM AUTHOR]

A new base metal catalyzed sustainable multicomponent synthesis of pyrroles from readily available substrates is reported. The developed protocol utilizes an air‐ and moisture‐stable catalyst system and enables the replacement of themutagenic α‐haloketones with readily abundant 1,2‐diols. Moreover, the presented method is catalytic in base and the sole byproducts of this transformation are water and hydrogen gas. Experimental and computational mechanistic studies indicate that the reaction takes place through a combined acceptorless dehydrogenation hydrogen autotransfer methodology. [ABSTRACT FROM AUTHOR]

The commercial high‐temperature water‐gas shift (HT‐WGS) catalyst consists of CuO‐Cr2O3‐Fe2O3, where Cu functions as a chemical promoter to increase the catalytic activity, but its promotion mechanism is poorly understood. In this work, a series of iron‐based model catalysts were investigated with in situ or pseudo in situ characterization, steady‐state WGS reaction, and density function theory (DFT) calculations. For the first time, a strong metal‐support interaction (SMSI) between Cu and FeOx was directly observed. During the WGS reaction, a thin FeOx overlayer migrates onto the metallic Cu particles, creating a hybrid surface structure with Cu‐FeOx interfaces. The synergistic interaction between Cu and FeOx not only stabilizes the Cu clusters, but also provides new catalytic active sites that facilitate CO adsorption, H2O dissociation, and WGS reaction. These new fundamental insights can potentially guide the rational design of improved iron‐based HT‐WGS catalysts. [ABSTRACT FROM AUTHOR]

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The catalytic activity of M(Ag, Ru, Pt)–Ni/CeO2–SiO2 catalysts prepared by wet impregnation at different M loadings (0–3 wt%) for oxidative steam reforming of ethanol (OSR) was investigated at H2O/C2H5OH = 4, O2/C2H5OH = 0.5, T = 300–600 °C and WHSV = 61.7 h−1. Ag deposition on the Ni/CeO2–SiO2 sample resulted in lower H2 yields, whatever the silver content. Conversely, Ru and Pt addition improved the performances of the monometallic sample and catalyst activity was enhanced by the reduction of metals loading. Similar results were recorded over the catalysts prepared at the same metals content and a metal loading of 0.5 wt% was sufficient to reach the highest performance in the investigated temperature interval. The kinetic model able to predict the experimental results obtained over the most promising formulations includes ethanol decomposition, methane oxidation and steam reforming, water gas shift; Pt as well as Ru addition to the Ni/CeO2–SiO2 sample reduced the activation energy of the involved reactions and Ru was demonstrated to be a valid substitute of the Pt for OSR of ethanol. Thus, by employing smaller noble metal content and less expensive materials, it is possible to reduce the catalyst price. [ABSTRACT FROM AUTHOR]

In this study, Kenaf biomass was gasified under subcritical liquid-vapor conditions and effect of initial water amount on gas composition and hydrogen production was evaluated at different temperatures. Gasification was carried out in a batch type reactor, with various initial water volumes (0, 12, 25, 50, 75 mL), at different temperatures (250, 275, 300, 325 °C) and with different catalysts (Ru/C, Pt/C, Na 2 CO 3 , Fe 2 O 3 , CaO, CaCO 3 and RuCl 3). The results revealed that the gasification efficiency and hydrogen selectivity are dramatically varied with initial water percentage that was fed to the reactor. The gaseous products obtained from hydrothermal gasification of kenaf were mainly H 2 , CO 2 , and in lower but varying amounts, CH 4 and C 2 H 4. Water soluble RuCl 3 was found to be more effective than water insoluble Ru/C catalyst on biomass gasification. RuCl 3 catalyst has a high catalytic activity for kenaf gasification with greater H 2 selectivity. Maximum total gas (462.5 mL) and H 2 mole fraction in the gaseous product (44.5%) were obtained at 250 °C with RuCl 3 catalyst. The maximum carbon conversion (%) was also obtained with RuCl 3 as 71.3%. Water behaves as both the reaction medium and the second main reactant beside biomass, during the subcritical liquid-vapor phase gasification process. • Initial water percentage of the reactor dramatically affects the hydrogen yield. • Activity of the catalysts was ranked as; RuCl 3 > Ru/C > Pt/C > Pd/C > Raney Ni. • Water soluble RuCl 3 has more catalytic activity than water insoluble Ru/C. • Operating temperature affects the product distributions and total gas formation. [ABSTRACT FROM AUTHOR]

Highlights • CO 2 capture from water-gas shift process was studied using a bench-scale pilot plant. • Comparative analysis of MDEA-PZ and novel MDEA-DA2MP was investigated. • The MDEA-DA2MP blend has higher mass transfer coefficient than MDEA-PZ. • MDEA-DA2MP blend has lower regeneration energy and higher CO 2 capture efficiency. • The optimal amine blend is 3 kmol/m3 MDEA-1 kmol/m3 DA2MP. Abstract This research is a bench-scale pilot plant investigation of novel amine solvent blend containing MDEA and 1,5-diamino-2-methylpentane (DA2MP) for CO 2 capture from water-gas shift process plant (H 2 production). The CO 2 concentration used in this study (50 vol.% CO 2 with N 2 balance) is similar to that of the water-gas shift product gas. The CO 2 capture performance of the MDEA-DA2MP blend was compared to the standard 3 kmol/m3 MDEA-0.5 kmol/m3 PZ blend (34.4 wt.% MDEA-5 wt.% PZ). The low concentration of PZ in this study is because of the chemical toxicity of PZ and possible precipitation at medium to high concentration. The MDEA concentration in the MDEA-DA2MP blend was kept constant at 3 kmol/m3 while the DA2MP was varied from 0.5 kmol/m3 (6.75 wt.%) to 1.5 kmol/m3 (20.3 wt.%). The pilot plant analysis was performed at a gas flow rate, amine solution flow rate, and reboiler temperature of 14 SLPM, 50 mL/min, and 120 °C respectively. Pilot plant results revealed that the higher MDEA-DA2MP blend concentration possesses higher CO 2 capture efficiency (up to 24%), higher CO 2 absorption rate (up to 23.5%) and higher absorber mass transfer coefficient (up to 23.9%) compared to the MDEA-PZ blend. It was also discovered that the high MDEA-DA2MP concentration has lower regeneration energy (up to 25.4%), lower initial amine solution utilized (up to 20.5%), lower desorber mass transfer coefficient (up to 32.5%) compared to the MDEA-PZ blend. However, the optimal amine concentration is the 3 kmol/m3 MDEA-1 kmol/m3 DA2MP blend. Overall results show that the MDEA-DA2MP blend can offer a cost-effective and energy efficient CO 2 capture compared to MDEA-PZ. [ABSTRACT FROM AUTHOR]

[Display omitted] • Techno-environmental-economic performance of the excavated waste to H 2 is studied. • Sorption enhanced water–gas-shift route has better performance. • The highest H 2 yield of refuse-derived fuel from excavated waste is 121.87 kg/ton. • The highest levelized profit of excavated waste is 185.78 $. The mismanagement of excavated waste (EW) is leading to serious land occupancy and greenhouse gases leakage problems globally. This study explores the possibility to realize utilization of EW and satisfaction of the hydrogen fuel demand at the same time. Based on plasma gasification (PG), the excavated waste has shown its potential to act as a sustainable source of hydrogen. In this study, the techno-environmental-economic performance of the EWtH (excavated waste to hydrogen) process based on PG-WGS-AGR (water gas shift-acid gas removal) and PG-SEWGS (sorption enhanced water gas shift) routes are investigated. The results demonstrate that the EWtH process based on the PG-SEWGS route has higher exergy efficiency, better environmental performance, and more promising economic feasibility. The EWtH process can maintain profitable when resisting the fluctuation of EW treatment subsidy, selling price of CO 2 and carbon tax (±75%), with the biggest LP EW (levelized profit of excavated waste) drop of 19.22%. However, as the selling of H 2 is the largest income, the LP EW has decreased to a negative value within the fluctuation of the selling price of H 2 in ± 55%, which suggests that the selling price of H 2 is the decisive factor in the economic feasibility of the EWtH process. Also, the EW with fewer landfill years brings higher profit, and the material recovery process plays a more significant role in the treatment of EW with longer landfill years. The highest exergy efficiency (57.79%) and the most environmentally friendly performance (-70.84 mPE) locates in the 05-EWtH process applying SEWGS, and the 15-EWtH process based on PG-SEWGS route has the highest LP EW of 185.78 $/ton EW. [ABSTRACT FROM AUTHOR]

• Effects of H2 co-injection via tuyere and shaft on the performance of an industrial scale blast furnace are quantified. • Impacts of water gas shift reaction on blast furnace performance are studied. • Interrelation between utilisation efficiencies of H2 and CO on isothermal lines is identified. • Operation strategies for H2-rich operation of blast furnaces are explored. Hydrogen (H 2) can be co-injected into the tuyere and shaft into a blast furnace (BF) for reducing CO 2 emissions. However, the feasible co-injection schemes and their effects on in-furnace phenomena are not well understood. In this study, a multi-fluid industrial-scale BF model is further developed to investigate the impacts of H 2 co-injection through the shaft and/or tuyere on the BF internal state and overall performance in terms of temperature field, H 2 and CO utilisation efficiency, and species distributions. The results show that the proposed H 2 co-injection through tuyere and shaft allows H 2 to be better utilized and the overall BF temperature field can be improved, compared to respective tuyere or shaft injection cases. Further, the effects of high hydrogen injection rate at tuyere (i.e., low hydrogen injection rate at shaft) are studied. It is found that with increasing H 2 injection ratio at tuyere, the water gas reaction and water gas shift reaction are intensified; the temperature is decreased and the H 2 utilization efficiency is suppressed; the raceway adiabatic flame temperature (RAFT) gradually decreases; the lowest coke rate is 285.8 kg-C/t-HM is found when the distribution ratio of injected H 2 is 4:6 at tuyere and shaft, and the highest coke replacement ratio is 4.1 kg-C/kg-H 2. Then, the possible operation strategies for H 2 -rich operation of blast furnaces are explored. This paper provides a cost-effective tool to understand the flow-thermal-chemical behaviours inside a BF when H 2 co-injection schemes are employed. [ABSTRACT FROM AUTHOR]

Digested water hyacinth with waste sludge as inoculum were obtained after anaerobic digestion at 35 and 45°C. High organic content of digested biomass were evaluated through gasification at supercritical conditions of water in the absence and presence of catalysts (KOH, NaOH, LiOH and K2CO3) with 10 wt.% of volatile solid in feed. Supercritical water gasification of digested biomass was performed in batch reactor system at temperature and pressure ranges of 500-600°C and 35-45 MPa, respectively. The highest carbon gasification efficiency, hydrogen and methane yields were reached at 600°C (with samples digested at 45°C) in the absence of catalyst as 84.6 (g C in gaseous/g C in digestate), 53.0 (mol H2%) and 14.2 (mol CH4%), respectively. High organic content of digested biomass was converted by supercritical water gasification to methane and hydrogen rich gas, and aqueous products (aliphatic hydrocarbons, phenol, substituted phenols, N-heterocyclic, substituted N-heterocyclics, and substituted benzene) that can be evaluated as platform chemicals. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the operation of a heat exchange integrated, Pt-CeO 2 /Al 2 O 3 washcoated microchannel water-gas shift (WGS) reactor under fuel processing conditions by mathematical modeling techniques. In this context, operation of a single microchannel is modeled, whose outcomes are compared with experimental data obtained from the literature. Simulations show good agreement with the experimental data, with an error below 4%. Upon its validation, single channel model is used to simulate a heat exchange integrated microchannel reactor, which involves periodically located groups of reaction and air-fed cooling channels. The integrated reactor is modeled by 2D Navier-Stokes equations together with reactive transport of heat and mass. Incorporation of heat exchange function minimizes the impact of thermodynamic limitations on WGS by precise regulation of reaction temperature and gives 77.6% CO conversion, which is 67.4% in the absence of cooling. Improvement in conversion from 69.2% to 77.6% is observed upon increasing feed temperature of the reaction stream from 565 to 595 K, above which the reaction is controlled by equilibrium. Coolant feed temperature, however, changes conversion only by <1%. Isothermal conditions are obtained upon feeding reaction and coolant channels at 595 K and 587 K, respectively. Changes in the thickness and material of the wall between the channels give limited deviations in conversion. An integrated reactor with 2.37 L volume is sufficient for supplying H 2 necessary to drive a 1 kW PEMFC unit. [ABSTRACT FROM AUTHOR]

• Effect of recycling of the exhaust emissions from internal combustion engines inside the air-blown gasification system is investigated. • A 2D CFD model is investigating the novel research idea and further study the combined effects on the gasifier performance. • A new parameter – CB ratio – is defined, which is the exhaust/emissions from ICE gases to the feedstock mass ratio. Optimum values of CB are recommended between (0.05–0.25). • The proposed design helps in preserving the environment, reducing CO 2 and GHG emissions, and increasing the gasifier performance. • The significant outcomes of the study are applicable for different scales of air-blown gasifiers. The current research presents a proposed system for the recycling of the exhaust emissions from internal combustion engines (ICE) inside the air-blown gasification system. A 2D Computational Fluid Dynamics (CFD) model is investigating the novel research idea and further study the combined effects on the gasifier performance. To this end, the numerical model will be validated against wide range of operating conditions. Additionally, the effect of exhaust emissions injection along with air (the gasifying medium) on gasification, carbon conversion, system performance, syngas composition, and yield will be investigated. A new parameter – CB ratio – is defined, which is the exhaust/emissions from ICE gases to the feedstock mass ratio. Optimum values of CB are recommended between (0.05–0.25). The research idea resulted in boosting the yield of H 2 , and CO by 10.3, and 3.3 mol.% respectively, and correspondingly, higher heating values by 5.8% within the optimum range of CB. For the same range, N 2 , and CO 2 emissions are found to decrease within the gasifier. The exhaust emissions stream with high temperature and rich content of CO 2 , and H 2 O resulted in higher turbulence, velocity, and mixing inside the gasifier. Thus, enhanced the gasification reactions i.e., boudouard, and water gas reactions. Moreover, producer gas yield, carbon conversion and gasification efficiencies are found to be 28, 10, and 11% higher than air gasification under the same working conditions respectively. The proposed design (20 kW gasifier) – i.e., small scale industrial gasification unit – is found to consume around 3.5 kg/hr of the ICE emissions. Thus, preserving the environment, reducing CO 2 and GHG emissions, and increasing the gasifier performance. The significant outcomes of the study are applicable for different scales of air-blown gasifiers. [ABSTRACT FROM AUTHOR]

Kinetic and pulse experiments were performed to elucidate the mechanism of the water–gas shift reaction (WGSR) under practical conditions. CO conversion was found to be significantly influenced by H 2. The reaction was strongly suppressed at high H 2 concentrations. A simple rate equation based on a competitive redox mechanism was derived. The H 2 O-induced oxidation of Cu0 to Cu+ was assumed to be the rate-determining step. H 2 affected the CO conversion rate because it competitively reduced Cu+ to Cu0. In the proposed rate equation, the rate constant k f determines the rate of the catalytic cycle and the selectivity factor κ may control the selectivity to CO conversion. CO-pulse experiments independently yielded the selectivity factor κ (1.38), which was almost identical to that obtained from the kinetic analysis (1.39). The coincidence of these values strongly corroborates the proposed competitive redox mechanism. [Display omitted] • A competitive redox mechanism is proposed for low-temperature WGSR over Cu-ZnO-Al 2 O 3. • The rate equation is a product of the oxidation rate and selectivity to reduction. • The detrimental effect of H 2 can be explained by the competitive redox mechanism. • Results of pulse experiments support the competitive redox mechanism. • The number of active surface-Cu0 sites can be estimated from the pulse experiments. [ABSTRACT FROM AUTHOR]

The environmental impact of increasing waste emissions and the demand for clean energy have led to the development of waste-to-energy technologies. Hydrogen, a clean energy carrier, can be produced via the water gas shift (WGS) reaction, accompanied by waste gasification. CuFe 2 O 4 spinel ferrite has been synthesized by various methods, such as co-precipitation, electrospinning, dehydration, sol-gel, and hydrothermal methods, and has been applied to the WGS reaction of waste-derived syngas. Among the different methods, the electrospinning method affords nanofiber-structured CuFe 2 O 4 , which showed the highest WGS activity which is attributed to its remarkable reducibility and easier formation of active species. It was also found that the distinct nanofiber structure of this catalyst prevents Cu sintering at high temperatures, resulting in stable activity during the WGS reaction. [Display omitted] • The WGS reaction was carried out to produce hydrogen from waste. • CuFe 2 O 4 synthesized by electrospinning exhibited the highest WGS performance. • It was due to the remarkable reducibility and easier formation of active species. • Nanofiber structure of CuFe 2 O 4 -ES is effective in preventing the Cu sintering. [ABSTRACT FROM AUTHOR]

Water vapor removal by the polymeric membrane to reduce the energy cost during the water–gas shift reaction in a catalytic membrane reactor was investigated. In this study, polyamideimide (PAI) defect-free hollow fiber membranes were produced by a dry/wet phase inversion method. The purpose of this study was to investigate the water vapor removal efficiency under high pressure and high temperature. The morphologies of the hollow fiber membranes were characterized by SEM. The water vapor and hydrogen mixed gas separation properties were used to verify the performance of a defect-free membrane. The water vapor removal efficiency increased from 54% to 90% (at 120 °C) as a function of the operating conditions because of the enhanced water vapor flux. However, the H 2 retention ratio was negatively related to the water removal efficiency. [ABSTRACT FROM AUTHOR]