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Nowadays, hydrogen is gaining attention as one of the green energy alternatives within transition to a zero-emission economy. Increasing demand for hydrogen and its production has prompted the development of low-carbon strategies and technologies for hydrogen generation from hydrocarbons. This paper provides a thorough analysis of traditional and innovative methods for hydrogen production from fossil feedstock, reviewing the critical aspects and recent advancements in the field. The paper emphasizes the potential of in situ hydrogen generation as the most promising method, taking into account CO2 emission concerns. Additionally, this study explores the use of software packages for modeling hydrogen production, outlining their advantages and disadvantages and proposing the most favorable software for in situ hydrogen generation from hydrocarbons. Subsequent analysis sheds light on the effectiveness, economic viability, environmental impact, and future perspectives of various hydrogen production technologies. • Overview of hydrogen production technologies: conventional and innovative methods. • Key issues and best practices of the latest experimental and numerical studies. • Comparative analysis of various hydrogen production technologies and approaches. • Subsurface hydrogen generation has a great development potential. • There are methods for clean hydrogen production from hydrocarbon feedstock. [ABSTRACT FROM AUTHOR]

Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH 4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH 4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H 2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH 4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides. [Display omitted] • Ni–CoP catalyst was electrodeposited on a carbon support. • Material characterization proved the formation of desired active layers. • High efficiency and stability of the catalyst for a long-term NaBH 4 hydrolysis was revealed. [ABSTRACT FROM AUTHOR]

• Co doped MoS 2 was decorated on nitrogen-doped carbon fiber/carbon paper (NCFCP) by a solvothermal process. • The lattice spacing of (1 0 0) plane of Co-MoS 2 was slightly narrow than that of MoS 2. • The as-prepared Co-MoS 2 /NCFCP hybrids showed enhanced electrochemical activity for HER. In this paper, Co-doped MoS 2 (Co-MoS 2) with various Co/Mo mole ratio (6%–12%) decorated on nitrogen-doped carbon fiber/carbon paper (NCFCP) (Co-MoS 2 /NCFCP) is fabricated by a solvothermal method as an efficient electrocatalyst for hydrogen evolution reaction (HER). The NCFCP substrate is prepared by electrochemical deposition of polypyrrole on carbon paper followed by heat treatment. The obtained 9% Co-MoS 2 /NCFCP hybrid catalyst exhibits an excellent electrocatalytic HER activity with a low overpotential of 174 mV at 10 mA cm−2, a small Tafel slope of 52 mV dec−1 and long-term stability. Thus, Co-MoS 2 /NCFCP hybrid holds high potential as an efficient earth-abundant electrocatalyst material for HER. [ABSTRACT FROM AUTHOR]

The continuous ortho-para hydrogen conversion technology represented by the plate-fin heat exchanger filled with catalyst (PFHEFC) is one of the key technologies for the breakthrough of large-scale hydrogen liquefaction system. An appropriate numerical model of the PFHEFC can provide reference and guidance for its design. The thermal-hydraulic behaviors of the catalyst filled layer (CFL) are essential for the model development of the PFHEFC. In this paper, the thermal-hydraulic correlations of the high-pressure and low-temperature hydrogen in the CFL are investigated by the numerical simulation and then used to improve the existing numerical models of the PFHEFC. The results show that the simulation results of the face centered cubic (FCC) packing structure are close to the results of some classical correlations of the CFL with most relative deviations within ±10% and can be used to approximate the actual CFL. And taking 40 K as the dividing point, the new thermal-hydraulic correlations of the high-pressure and low-temperature hydrogen in the CFL are obtained with the relative deviations within ±10%. Further, the New model of the PFHEFC is developed with the new thermal-hydraulic correlations. The New model has some margin in the heat transfer performance, considers the special thermal-hydraulic performances of the high-pressure and low-temperature hydrogen in the CFL, and is consistent with the existing numerical models in the ortho-para hydrogen conversion performance. It shows the New model is more suitable for the PFHEFC and can provide more accurate results for the design of the PFHEFC than the existing numerical models. • Assumption of the FCC approximating the actual CFL is reasonable and enforceable. • Thermal-hydraulic behaviors of high-pressure hydrogen at 30–80 K in the CFL are analyzed. • Porosity is a nonnegligible parameter affecting the thermal-hydraulic performances of the CFL. • New thermal-hydraulic correlations of high-pressure hydrogen at 30–80 K are obtained. • New model of the PFHEFC is proposed and is better than the existing numerical models. [ABSTRACT FROM AUTHOR]

This paper is focused on the photocatalytic hydrogen production on Pd/TiO 2 (-WO 3) catalysts from water-methanol and water-glycerol mixtures under UVA and solar irradiation. The photodeposition method for Pd was studied varying conditions such as Pd amount, catalyst concentration and methanol concentration. The catalysts were tested at lab scale under simulated solar light and UVA radiation and also at large scale (25 L) under solar energy using a pilot-scale solar Compound Parabolic Collector (CPC). The catalysts characterization was performed by means of ICP-OES, N 2 adsorption–desorption isotherms, XRD, HR-TEM, XPS and DR–UV–Vis spectroscopy. Hydrogen evolution was monitored by on-line gas chromatography.From results it was found the Pd photodeposition method plays a key role to increase the hydrogen evolution, affecting parameters like the Pd amount deposited, the Pd nanoparticles size and dispersion. The highest quantum efficiency (ϕ) obtained in this study was 11.8% and 41.2% under simulated solar and UVA irradiation, respectively, using Pd(0.24 wt%)/P25 in an aqueous solution of methanol (50 vol%). In the pilot-scale solar CPC, for Pd(0.24 wt%)//P25 catalysts in 5 vol% of methanol or glycerol as sacrificial agents, the quantum yield were 2.1 and 2.2%, respectively. When the concentration of the sacrificial agents decreased to 0.37 vol%, the quantum yields were 1.3 and 2.4% for methanol and glycerol, respectively. Compared to literature, the low noble metal content of these catalysts (0.25 wt%) seems to be a competitive factor considering their high price. • Efficient catalysts for H 2 generation under solar radiation obtained by Pd photodeposition over TiO 2 and WO 3 supports. • Pd photodeposition method plays a key role in the hydrogen evolution, affecting parameters such as the nanoparticles size. • Low H 2 evolution with municipal wastewater demonstrates the challenges to overcome the photocatalytic H 2 generation. [ABSTRACT FROM AUTHOR]

Over the course of a few decades, the concern of environmental damages of fossil fuels, an increase in CO 2 emission and a decrease of hydrogen have been growing more and more. Accordingly, hydrogen production is a crucial issue nowadays. Different polymers are applied to attain the purpose. Among all polymers, biodegradables polymers are the best choices to develop the main aim. Polysaccharides and proteins are biodegradable polymers with unique places and advantages with regards to their ecofriendly properties. There are different techniques to apply and achieve the foremost purpose. It is worthwhile to mention that green and facile methods are always attracting attention in different aspects and fields. The three non-polluting and economical techniques, that is, electrochemical hydrogen evolution reaction (HER), photocatalytic technique, and hydrolysis of hydrides, are reviewed in this paper. This review helps researchers, who are environment supporters, to evaluate and choose the most ecological biopolymers and processes in their work. [Display omitted] • Developments in hydrogen evolution by biopolymer-derived (nano)catalysts have been described. • Summary of synthetic procedures to obtain biopolymer-derived (nano)catalysts. • Future challenges of hydrogen evolution using biopolymer-derived (nano)catalysts have been discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the hot gas temperature effect on enhancing hydrogen generation and minimizing tar yield using zeolite and prepared Ni-based catalysts in rice straw gasification. Results obtained from this work have shown that increasing hot gas temperature and applying catalysts can enhance energy yield efficiency. When zeolite catalyst and hot gas temperature were adjusted from 250 °C to 400 °C, H 2 and CO increased slightly from 7.31% to 14.57%–8.03% and 17.34%, respectively. The tar removal efficiency varies in the 70%–90% range. When the zeolite was replaced with prepared Ni-based catalysts and hot gas cleaning (HGC) operated at 250 °C, H 2 contents were significantly increased from 6.63% to 12.24% resulting in decreasing the hydrocarbon (tar), and methane content. This implied that NiO could promote the water-gas shift reaction and CH 4 reforming reaction. Under other conditions in which the hot gas temperature was 400 °C, deactivated effects on prepared Ni-based catalyst were observed for inhibiting syngas and tar reduction in the HGC system. The prepared Ni-based catalyst worked at 250 °C demonstrate higher stability, catalyst activity, and less coke decomposition in dry reforming. In summary, the optimum catalytic performance in syngas production and tar elimination was achieved when the catalytic temperature was 250 °C in the presence of prepared Ni-based catalysts, producing 5.92 MJ/kg of lower heating value (LHV) and 73.9% tar removal efficiency. Image 1 • Prepared Ni-based catalyst can enhance hydrogen production in biomass gasification. • Zeolite at 400 °C generates more H 2 content comparing to prepared Ni-based catalyst. • Ni-based catalyst at 400 °C is deactivated by sulfur poison and coke decomposition. • Ni-based catalyst is not guaranteed to be effective for trace pollutants removal. [ABSTRACT FROM AUTHOR]

Chemical hydrogen storage in molecules such as ammonia (>17 wt% H 2) have the unique potential to overcome the current storage and transport limitations of the H 2 economy. However, sustainable on-demand production of hydrogen via ammonia decomposition, requires the development of novel transition metal-based catalysts beyond the current use of highly active but expensive ruthenium to ensure economic feasibility. In this paper, we provide fundamental understanding of the effects of a range of synthetic methods of Co/γ-Al 2 O 3 catalysts on the resulting ammonia decomposition activity. The main activity determining factors are collectively the reducibility of the cobalt species and their particle size. This systematic work demonstrates that decreasing the cobalt particle size enhances the ammonia decomposition catalytic activity. However, a careful balance is required between a strong metal-support interaction leading to small particle sizes (promoted by precipitation methods) and the formation of inactive cobalt aluminate species (encouraged by adsorption methods). In addition, impurities such as boron and chloride remaining from particular synthetic methods were found to have detrimental effects on the activity. Image 1 • High H 2 production from ammonia on cobalt-based catalysts. • Guidance for future cobalt-based catalysts development to replace scarce Ru. • Cobalt particle size plays a key parameter on ammonia decomposition activity. • Cobalt catalyst preparation method affects its size and interaction with support. • Strong-cobalt support interaction leads to formation of unreducible and inactive species. [ABSTRACT FROM AUTHOR]

In this paper, we present a solvothermal synthesis of iron phosphide electrocatalysts using a triphenylphosphine (TPP) precursor. The synthetic protocol generates Fe 2 P phase at 300 °C and FeP phase at 350 °C. To enhance the catalytic activities of obtained iron phosphide particles heat-treatments were carried out at elevated temperatures. Annealing at 500 °C under reductive atmosphere induced structural changes in the samples: (i) Fe 2 P provided a pure Fe 3 P phase (Fe 3 P−500 °C) and (ii) FeP transformed into a mixture of iron phosphide phases (Fe 2 P/FeP−500 °C). Pure Fe 2 P films was prepared under argon atmosphere at 450 °C (Fe 2 P−450 °C). The electrocatalytic activities of heat-treated Fe 2 P−450 °C, Fe 3 P−500 °C, and Fe 2 P/FeP−500 °C catalysts were studied for hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4. The HER activities of the iron phosphide catalyst were found to be phase dependent. The lowest electrode potential of 110 mV vs. a reversible hydrogen electrode (RHE) at 10 mA cm−2 was achieved with Fe 2 P/FeP−500 °C catalyst. Image 1 • Iron phosphides catalyst were synthesized via a wet-chemistry method. • Spin-coating of iron phosphide particles onto graphite substrates yielded uniform thin films. • Heat treatment of iron phosphides at 500 °C resulted in structural changes. • The iron phosphide films were used as electrocatalysts for efficient hydrogen evolution. [ABSTRACT FROM AUTHOR]

Steam reforming of biomass pyrolysis oil or bio-oil derivatives is one of the attractive approaches for hydrogen production. The current research focused on the development of promising catalysts with favorable catalytic activity and high coke resistance. Noble metal such as Rh has been proven to achieve promising reforming reaction efficiencies. However, Ni has attracted considerable attention owing to its stability, cost effectiveness, and good activity in breaking C–C and C–H bonds. Nevertheless, Ni-based catalysts have serious carbon deposition problems arising from chemical poisoning, metal sintering, and poor metal dispersion. This paper attempted to review the current trends in catalyst development considering the aspects of supports, metals, and promoters as an effort to find possible solutions for the limitations of Ni-based catalysts. The present review also covered the current understanding on the reaction mechanisms as well as the future prospects in the field of steam reforming catalysts. Image 1 • Catalysts efficiency rely on nature of metal, support, and metal-support interface. • Advanced catalyst synthesis is a new direction for achieving promising catalyst. • Mechanism of oxygenates compounds steam reforming is well discussed. • Further studies to elucidate mechanism of bio-oil steam reforming are required. [ABSTRACT FROM AUTHOR]

This paper presents high-performance Ni-YSZ tubular catalysts for CO 2 methanation prepared by the extrusion molding. We fabricated tubular-shaped Ni-YSZ catalysts with various Ni contents (25–100 wt% NiO) and investigated the effect of Ni content on CO 2 methanation performance under various temperatures and gas flow rates. Catalysts with Ni contents >75 wt% showed CH 4 yields >91% above 270 °C with high CH 4 selectivities (>99%). High CH 4 yields were also observed under high GHSVs at 300 °C: 93% and 92% at 8700 and 17,500 h−1, respectively. Investigation of methanation with the catalysts revealed that CO 2 methanation was accelerated by a localized hotspot at the reactor inlet arising from the interaction between reaction kinetics and heat generation. Using a numerical simulation, we considered the optimum arrangement of catalytic activity in the reactor to avoid hotspot generation and realize a stable high CO 2 methanation performance. We can simultaneously achieve high CH 4 production and prevent hotspot formation by properly arranging catalysts with different activities. • Ni content >75% gave CH 4 yields >91% above 270 °C with selectivities >99%. • Inlet hotspot arises from interaction of heat generation and reaction acceleration. • Increasing catalytic activity along reactor length can avoid hotspot formation. [ABSTRACT FROM AUTHOR]

In this paper energy dispersive spectroscopy, X-ray diffraction and Williamson-Hall grain size/strain characterization techniques were used to determine the effect exhaust water electrical conductivity, heating and electrical current had on Proton Exchange Membrane electrocatalyst degradation and the underlying mechanism. Quartz containing polybenzimidazole polymer had 6 nm of platinum sputter-coated and while 50 to 400 cycles of either 0.7 mA or 30 mA current were applied. Results showed between 38% (overall) and 100% (locally) platinum removal using 0.7 mA (400 cycles) or 30 mA (50 cycles) using water with 5 vol% acetic acid. The acetic acid increased the water's electrical conductivity and helped transport quartz to the sample surface to interact with the platinum. This interaction increased quartz's lattice strain to 1.4% and resulted in detached platinum. Furthermore, similar results may occur using membranes formulated with acid side chains, which can leach during thermal decomposition and destroy stack performance. Image 1 • Heating >100 °C using water & acetic acid did not detach catalyst from membrane. • Electrical current, quartz & conductive water detached catalyst from membrane. • Electrically conductive water critical component to remove catalyst from membrane. • Larger electrical current magnitudes removed catalyst at faster detachment rates. • Mechanism involved diffusion of quartz & catalyst increasing quartz lattice strain. [ABSTRACT FROM AUTHOR]

In this paper, different methods to prepare a Pt/stainless steel mesh catalyst for catalytic hydrogen combustion are reported. Pt was deposited as a thin layer onto stainless steel mesh as a support matrix. Thermal treatment resulted in the formation of uniformly distributed near nano-sized Pt particles on the support's surface. The catalysts were evaluated for catalytic hydrogen combustion, and temperatures of between 420 and 520 °C were achieved and maintained at hydrogen flow rates of 0.2–0.4 Nl/min. SEM and EDX results indicate that stainless steel support calcination promoted the formation of a native oxide layer. This oxide layer stabilized Pt particles during hydrogen combustion procedures, effectively preventing significant Pt aggregation from occurring. It was also found that the Ni content of stainless steel promoted the catalytic hydrogen combustion reaction. • Pt/stainless steel mesh catalysts were developed and evaluated for catalytic H 2 combustion applications. • High temperatures associated with catalytic H 2 combustion allowed for significant Pt-aggregation. • Catalysts with stabilized Pt achieved H 2 combustion temperatures of 420–520 °C, which were maintained for several hours. • Spontaneous auto ignition occurred on catalysts above 40 °C. • Significant reduction in NO x formation occurs from catalytic combustion compared with naked flame combustion. [ABSTRACT FROM AUTHOR]

Food waste is a kind of wet bio-waste which has been a challenge for the ecological environment and disposal. In this paper, hydrogen production from subcritical water gasification (SbWG) of food waste with and without catalyst loading was systematically investigated. The effects of reaction temperature (300–360 °C), residence time (30–90 min), food waste concentration (10–30 wt%) and catalysts (Ni/γ-Al 2 O 3 , Ni/ZrO 2 , NaOH, KOH, and FeCl 3) were studied within a pressure range of 10.5–20 MPa. The optimal process condition for SbWG of food waste without catalysts loading was determined to be 360 °C and 90 min with 10 wt% food waste. The liquid products and hydrochar were characterized by TOC, TGA/DTG, and SEM. The TOC concentration of liquid products decreased vastly with increasing reaction temperature. The highest H 2 yield (1.88 mol/kg), H 2 mole fraction (35.01%), and H 2 selectivity (53.86%) were achieved at 360 °C for 90 min with 5 wt% loading of KOH. It can be concluded that the performance of the catalysts for improving hydrogen production in SbWG of food waste was in the following order: KOH > NaOH > Ni/γ-Al 2 O 3 > Ni/ZrO 2 > FeCl 3. The catalytic SbWG can be a potential alternative for energy conversion of food waste and hydrogen production. Image 1 • Catalytic subcritical water gasification of food waste was investigated. • Optimal operating condition were found to be 360 °C, 90 min with 10 wt% food waste. • Alkaline metals, Ni-based, and Lewis acid catalysts were comprehensively studied. • Activity of the catalysts was ranked as: KOH > NaOH > Ni/γ-Al 2 O 3 > Ni/ZrO 2 > FeCl 3. [ABSTRACT FROM AUTHOR]

The bifunctional catalyst provided a novel platform for biomass pyrolysis to efficiently and cleanly produce hydrogen, realizing the high-value conversion of biomass. First, the effect of catalyst/biomass ratios on the reaction activity of the Mo 0.5 Ni 1 Ca 7 catalyst was investigated. On this basis, the effects of La 2 O 3 and LaCoO 3 stabilizers on the cycling stability of the Mo 0.5 Ni 1 Ca 7 catalyst were examined. Eventually, the catalytic mechanism and the anti-deactivation model of the Mo 0.5 Ni 1 Ca 7 -LaCoO 3 catalyst were proposed in this paper. The results showed that the LaCoO 3 perovskite-type stabilizer greatly enhanced the cycling stability of the catalyst. In particular, the H 2 yield of the Mo 0.5 Ni 1 Ca 7 -LaCoO 3 catalyst was slightly reduced from 402 mL g biomass − 1 to 392.05 mL g biomass − 1 after ten cycles, with a relative decrease of only 2.47%. After ten regeneration cycles, the Mo 0.5 Ni 1 Ca 7 -LaCoO 3 catalyst maintained high oxygen activity, demonstrating that the catalyst exhibited stable coke resistance. The surface structure of the catalyst was optimized after ten cycles with the formation of more fine particles, which allowed the catalyst to maintain a high activity. The excellent dispersion of the LaCoO 3 stabilizer effectively inhibited the sintering of CaO and NiO. It delayed the aggregation of CaMoO 4 , leading to a stable catalytic ability and adsorption capacity of the catalyst. [Display omitted] • Corn cob pyrolysis for hydrogen-rich gas realizes high value utilization of biomass. • The Mo 0.5 Ni 1 Ca 7 -LaCoO 3 catalyst has the largest NiO/Ni(OH) 2 and lattice oxygen ratio. • The CaMoO 4 alloy enhances the catalytic activity and stability of the catalyst. • The LaCoO 3 perovskite-type stabilizer inhibits active phase particle sintering. • After ten cycles, the H 2 yield is 392.05 ml/g, with a decrease of only 2.47%. [ABSTRACT FROM AUTHOR]

• The predictive ability of ΔG H for TMPs is enhanced by the integrated algorithm. • In terms of data sources, simply combining experimental or calculated data. • Feature importance analysis includes global and local feature importance. Transition metal phosphides (TMPs) are potential substitutes for platinum group metal catalysts in hydrogen evolution reactions (HER) for sustainable energy. In this work, a novel machine learning (ML)-based technique for HER performance prediction of TMPs is presented. ΔG H , which assesses catalytic activity, was utilized as the expected target value and data from sources like collected papers and self-calculated data were also employed. The random forest (RFR) technique produced an R2 of 0.89 on the test set, while non-tree ML algorithms were utilized for learning and feedback. Additionally, TMPs of ΔG H were predicted using an original Ensemble learning technique. The ensemble learning method significantly increased the model's predictive effect and strengthened the model's stability and resilience, resulting in an R2 >0.85 on the test set for the tree algorithm model. The SHAP (SHapley Additive exPlanations) algorithm and RFR showed that the geometric means of atomic volume, first ionization energy, and p-orbital electron number significantly impact free energy performance evaluation by tree ML algorithms. These findings can effectively guide the design and development of new products. In conclusion, this approach offers a useful tool to assess TMPs' performance in HER studies. [Display omitted] [ABSTRACT FROM AUTHOR]

• Al-rich Cu@MFI catalyst was developed for furfuryl alcohol upgrading to pentanediols. • The maximum yield of pentanediols was 91.7%% in a continuous-flow reactor. • The excellent activity was attributed to the proximity of Brønsted acid and metal sites in Cu@HZ40. • The catalyst exhibits excellent anti-sintering performance in a high-temperature hydrogen environment. Bifunctional metal-acid catalysts have been widely used in the process of upgrading the molecules of biomass. As an important bifunctional catalyst, metal @ zeolite exhibits excellent sintering resistance and efficient catalytic performance, which is significant for improving practical applications. While the development of Al-rich zeolite-confined nanocluster catalysts is still a considerable challenge. In this paper, Cu@ZSM-5 (SiO 2 /Al 2 O 3 = 40) catalyst with Al-rich ZSM-5 zeolite-confined copper nanoclusters were designed and synthesized by the in-situ ligand-assisted hydrothermal crystallization method. The average size of the encapsulation metal clusters was only 2.3 nm after treatment at 400°C for 2 h in a hydrogen environment, which exhibits excellent thermal stability. 27Al MAS NMR and Pyridine-adsorbed IR (Py-IR) spectra confirmed that Al was successfully introduced into the zeolite framework. The intimate metal- Brønsted acidic site distribution enables complete conversion of furfuryl alcohol and 92.1 % selectivity of pentanediols. DFT calculations revealed that the high catalytic activity in catalyzing the ring opening of furfuryl alcohol to pentanediols could be attributed to the unique electronic effect in the Al-rich catalyst Cu@ZSM-5 (SiO 2 /Al 2 O 3 = 40). The in-situ ligand-assisted hydrothermal crystallization method will be very attractive regarding the simplicity required for industrial production. The Al-rich Cu@ZSM-5 (SiO 2 /Al 2 O 3 = 40) catalyst was endowed with rich and dense metal-Brønsted acidic sites by a simple in-situ synthesis method, providing a practical and feasible path for the high-value utilization of biomass molecules. Al-rich Cu@MFI catalyst encapsulating copper nanoparticles exhibits significant pentanediols selectivity and high anti-sintering performance in boosting furfuryl alcohol upgrading to pentanediols. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new Ni/Co 9 S 8 non-precious heterostructure electrocatalyst for alkaline hydrogen evolution electrocatalysis was fabricated. • An ultralow overpotentials of 76 mV for HER at 10 mA cm−2 in 1.0 M KOH was achieved on the optimized electrocatalyst. • The Ni/Co 9 S 8 @FP is able to maintain a current density of 100 mA cm−2 at 380 mV (vs. RHE) for 37 h. • The synergistic effect of Ni and Co 9 S 8 lead to the moderate hydrogen adsorption on Ni surface, thus improving the interfacial water dissociation. Hydrogen from electrolysis cell driven by sustainable electricity is one of the most clean and renewable energy sources. The design and synthesis of efficient and robust noble-metal-free electrocatalyst for hydrogen evolution reaction (HER) are of paramount importance in modern society. Herein, we developed a simple two-step strategy to construct a new Ni/Co 9 S 8 heterostructure using carbonised (900 °C) filter paper (FP) as a precious metal-free electrocatalyst for hydrogen evolution reaction (HER) in alkaline media. The optimized electrocatalyst can achieve an ultralow overpotentials of 76 mV for HER at 10 mA cm−2 in 1.0 M KOH. Moreover, it can be maintained a current density of 100 mA cm−2 at 380 mV (vs. RHE) for 37 h. More importantly, experimental and theoretical calculations reveal that the remarkable enhancement of HER activity could be attributed to the synergistic effect of Ni and Co 9 S 8 that lead to the moderate hydrogen adsorption on Ni surface and improve the water dissociation at the interface of Ni/Co 9 S 8. Our work paves a new pathway to design high-efficient electrocatalysts for massive hydrogen production. [Display omitted] [ABSTRACT FROM AUTHOR]

Synthesis gas production is a technology that dates to the 1950s. Recently, the conversion of hydrocarbons to syngas has played an important role in various applications from gas-to-liquid (GTL) processes to fuel cell applications. However, the current industrial production method is only profitable when large quantities of syngas are produced and generates high amounts of CO2 as a by-product. With the growing demands for smaller-scale and mobile syngas production technology, the catalytic partial oxidation of hydrocarbons has become a promising alternative to the conventional methane steam reforming technology. With the infrastructure for production and distribution of many commercial fuels already in place, numerous studies have been done on conversion of these fuels into syngas. This paper reviews the research that has been done in the past decade on the catalytic partial oxidation of conventional fuels and biofuels. The challenges faced in catalyst development are described as well as solutions that have been proposed to address those challenges. Advances in kinetic modelling of catalytic partial oxidation are presented, and techniques used to develop such models have also been highlighted. Finally, research gaps have been identified and recommendations have been given for further investigations to address current challenges. [ABSTRACT FROM AUTHOR]

One of the most attractive routes for the production of hydrogen or syngas for use in fuel cell applications is the reforming and partial oxidation of hydrocarbons. The use of hydrocarbons in high temperature fuel cells is achieved through either external or internal reforming. Reforming and partial oxidation catalysis to convert hydrocarbons to hydrogen rich syngas plays an important role in fuel processing technology. The current research in the area of reforming and partial oxidation of methane, methanol and ethanol includes catalysts for reforming and oxidation, methods of catalyst synthesis, and the effective utilization of fuel for both external and internal reforming processes. In this paper the recent progress in these areas of research is reviewed along with the reforming of liquid hydrocarbons, from this an overview of the current best performing catalysts for the reforming and partial oxidizing of hydrocarbons for hydrogen production is summarized. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2), as a promising catalyst, has been widely investigated for hydrogen evolution reaction (HER). But the low density and poor reactivity of active sites, poor electrical transport, and inefficient electrical contact to the catalyst, leads to the modest performance. In this work, we demonstrate an effective route to overcome those issues by decorating the conductive LixMoS2 nanoparticles on the three-dimensional carbon fiber paper (CFP) through combining hydrothermal method and lithium intercalation. Thus, the dense LixMoS2 nanoparticles of the surface can provide the large number of exposed active sites, the highly-conductive LixMoS2 nanoparticles and CFP substrate can facilitate the transfer of electron not only between the LixMoS2 nanoparticles and CFP, but also between the whole sample and current collector, and the porous networked structure can enable the diffusion and penetration of electrolyte. Prompted by those advantage, the as-prepared samples exhibit outstanding HER catalytic activity with the small Tafel slope of 62 mv dec−1 and the low overpotential of −115.6 mV vs RHE at an electrocatalytic current density of 10 mA cm−2. Chronoamperometric current test for 10 h confirms the long-term stability of the catalyst. [ABSTRACT FROM AUTHOR]

The management of plastic wastes has become an urgent issue due to the overconsumption of single-use plastic products. As a promising avenue for plastic waste valorization, chemical recycling by converting plastics into value-added products has attracted tremendous attention. In this paper, the Fe-Ni alloy catalysts via in-situ exsolution were employed for the straightforward microwave plasma-initiated decomposition of plastic wastes for high yield H 2 and carbon nanotubes. The partial substitution of Fe by Ni promoted in-situ exsolution of alloy nanoparticles homogeneously. Specifically, characterization results showed that the introduction of Ni modulated metal-support interaction, which further affected the crystalline phase, nanoparticle size and oxygen vacancies. The exsolved Fe-Ni alloy catalyst exhibited the highest catalytic activity, over which 96 % hydrogen of plastic wastes rapidly evolved out in the form of gas products accompanied with high-purity carbon nanotubes. The H 2 yield was 415 mmol·g−1H plastic , which exhibited an over 2 times improvement versus the supported catalyst. Moreover, the successive cycle test displayed the potential for converting plastic wastes into H 2 -rich fuels and high-quality CNTs continuously. Generally, the in-situ exsolution strategy of Fe-Ni alloy catalysts contributed to the sustainable and high-efficient recycling of plastic wastes into H 2 -rich gas products and carbon nanotubes under microwave plasma. [Display omitted] • Partial substitution of Fe by Ni promoted in-situ exsolution of nanoparticles. • 96 % hydrogen was converted into gas fuels with H 2 yield of 415 mmol·g-1H plastic. • H2 yield of Fe 0.7 Ni 0.3 -Al 2 O 3 increased over 2 times versus the supported catalyst. • High quality CNTs were fabricated over exsolved Fe-Ni alloy catalyst continuously. [ABSTRACT FROM AUTHOR]

Abstract: The paper deals with fluidized bed gasification of a biomass for producing a syngas with optimized hydrogen yield thanks to in-bed catalysis. Four different bed materials have been adopted: inert quartzite as reference case, olivine and dolomite as natural catalysts, and Ni-alumina as artificial catalyst. The gasification tests have been carried out at steady state in a pilot-scale bubbling fluidized bed, under operating conditions typical for gasification as reported in the paper. The gas analyses have been performed with dedicated instrumentation, like continuous analyzers and gas chromatograph, and adopting a standard protocol for tar sampling and characterization. The influence of the catalytic materials on the concentration of stable gases (e.g. H2, CO2, CO, CH4 and light hydrocarbons) as well as on the efficiency of tar conversion has been studied. In particular the artificial catalyst has the largest effectiveness in enhancing the H2 yield as well as in tar reduction. The catalyst gives rise to an elutriation rate significantly lower than that observed for dolomite at comparable U/U mf ratio, denoting a better mechanical resistance. A stable activity of the nickel–alumina catalyst has been observed for the whole duration of reaction tests suggesting that no deactivation phenomena occurred, due to coke deposition or morphological modifications of the particles. [Copyright &y& Elsevier]

Abstract: This is the third in a series of papers by our team on apparently anomalous Balmer series line broadening in hydrogen containing RF generated, low-pressure () plasmas. In this paper the selective broadening of the atomic hydrogen lines in pure and mixtures in a large general electronics conference (GEC)-type cell (36cm length ID) was mapped as a function of position, ratio, time, power, and pressure. Several observations regarding the selective line broadening were particularly notable as they are unanticipated on the basis of earlier models. First, the anomalous broadening of the Balmer lines was found to exist throughout the plasma, and not just in the region between the electrodes. Second, the broadening was consistently a complex function of the operating parameters, particularly gas composition (highest in pure position, power, and pressure. Clearly, not anticipated by earlier models were the findings that under some conditions the highest concentration of “hot” () hydrogen was found at the gas entry end, and not in the high-field region between the electrodes, and that in other conditions, the hottest H was at the (exit) pump (also grounded electrode) end. Third, excitation and electron temperatures (measured optically) were less than 1eV in all regions of the plasma not directly adjacent () to the electrodes, providing additional evidence that the energy for broadening, contrary to standard models, is not obtained from the electric field. Fourth, in contrast to our earlier studies of hydrogen/helium and water plasmas, we found that in some conditions 98% of the atomic hydrogen was in the “hot” state throughout the GEC-type cell. Virtually every operating parameter studied impacted the character of the hot H atom population. Clearly, second and third order effects exist, indicating a need for experimental design. Some non-field mechanisms for generating hot hydrogen atoms are outlined. [Copyright &y& Elsevier]

Abstract: Hydrogen for use in fuel cells is produced in a fuel processor by the catalytic reforming of hydrocarbons. Experimental results from synthetic diesel and JP8 autothermal reforming activity tests performed over a commercial Pt/ceria catalyst was presented in part I of this paper. A reversible–irreversible poisoning phenomenon affected the catalyst''s activity. The objective of this paper is to present the results of characterization studies on these catalysts. Temperature programmed reduction (TPR) studies suggest that the oxidation–reduction properties of ceria are affected by poisoning. Temperature programmed desorption (TPD) and XPS analysis confirmed the formation of chemisorbed sulfur entities (irreversible poisoning). Based on these findings, a global deactivation mechanism is proposed. Experiments confirmed that the poisoning is reversible and is enhanced at higher temperatures in presence of a reducing environment. [Copyright &y& Elsevier]

Abstract: Hydrocracking is widely practiced by the refiners to convert heavy petroleum feedstocks into desired lighter products. There are many process variables and catalyst formulations for optimization of hydrocracker performance with respect to yield pattern, products’ quality and catalyst life. A user-friendly steady state hydrocracker model (HC-MOD) has been developed based on novel continuum theory of lumping approach for simulating hydrocracking kinetics and heat effects in a commercial hydrocracker. The model formulation includes skewed Gaussian type primary yield distribution function to describe yield and selectivity of the hydrocracking components. The model provides excellent prediction of commercial units’ performance, as it incorporates hydrocracking kinetics of paraffins, naphthenes, and aromatics. The capabilities of HC-MOD include prediction of products’ yields and qualities, reactor bed temperature profile, estimation of chemical hydrogen consumption, etc. In the present paper, case studies from operating refineries are presented where HC-MOD has been successfully applied for optimization and troubleshooting, leading to better performance. The cases involve: (i) solving low conversion problem in a two stage hydrocracker, (ii) catalyst selection for maximum middle distillates, and (iii) increase in middle distillates selectivity through optimization of operating conditions. The paper also describes the knowledge-based solutions, which have led to the significant benefits to the operating refineries. [Copyright &y& Elsevier]

In this paper, a simple method of NaHCO 3 reduction to CH 3 COOH in water with Al powder as a reductant on a commercially available Pd/C catalyst is described that producing CH 3 COOH with a good yield of 8% from NaHCO 3 on a carbon basis at 300 °C under hydrothermal conditions. A high adsorption enthalpy of C 1 intermediates on the Pd catalyst may act as an important role in the reduction of NaHCO 3 into CH 3 COOH on Pd/C catalyst. This research provides a simple way to convert the CO 2 into a C 2 compound. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the DME ATR reaction with different types of precious metal (Pt, Rh, Ru)-supported CGO catalysts. We also evaluated the reaction characteristics of DME ATR reaction by modifying certain reforming conditions, including the temperature, the amount of air and water, and the flow rate. The Ru-added CGO catalyst showed the best performance in DME ATR. The operating condition that produced the greatest effect on conversion efficiency was temperature; however the amounts of steam and air were also important with regard to conversion efficiency and the reaction heat. In case higher GHSV conditions the methane yields are increased. To maximize conversion efficiency with thermal neutral operating conditions, we suggest an SCR of 1.5, OCR of 0.45, over temperature of 700 °C, and a GHSV of less than 20,000/h. Under harsh conditions, such as low temperature and high GHSV, the methane yield increases. Therefore, the high temperature DME ATR reaction seems to consist of two main steps: the DME decomposition to methane and the methane autothermal reforming reaction. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of NO x to nitrogen by hydrogen (H 2 -SCR) does not result in any secondary pollutants and can reduce NO x at the lowest possible temperatures. To achieve this goal, proper catalysts are critical. In this paper, NiFe 2− x Pd x O 4 catalysts were prepared using a sol–gel auto-ignition method for the selective catalytic reduction of NO with hydrogen (H 2 -SCR) in the presence of oxygen at 150–250 °C. The NiFe 2− x Pd x O 4 catalysts exhibited high SCR activity providing 100% NO conversion at 190 °C, and the activity improved as the palladium content increased. NiFe 1.90 Pd 0.10 O 4 exhibited a slightly lower activity in the 180–220 °C range. NiFe 1.93 Pd 0.07 O 4 and NiFe 1.95 Pd 0.05 O 4 exhibited larger acidity, higher level of reducibility and catalytic activity, which was validated through NH 3 -TPR, H 2 -TPR analysis and SCR activity tests. The XRD results indicated that the samples had a spinel cubic structure with good crystallization. The EDS results indicated that the Fe/Ni and Pd/Ni atomic ratio in the samples were consistent with the theoretical molecular formula (i.e., NiFe 2− x Pd x O 4 ). The effects of GHSV, H 2 /NO ratios and O 2 feed concentration on the NO conversion over the NiFe 1.95 Pd 0.05 O 4 catalyst were also investigated. An increase in the O 2 concentration from 0% to 6% and a decrease in the H 2 /NO ratio from 10:1 to 5:1 produced only a slight decrease in the NO conversion. Studies on the effect of 3% and 5% H 2 O on the SCR activity concluded that the slight activity decrease, was due to reversible inhibition and weakly irreversible deactivation, and that the catalysts contained excellent water tolerance. [ABSTRACT FROM AUTHOR]

The preparation, characterization, activity, and stability of a Ni–Al 2 O 3 catalyst derived from reduction of a Ni–Al layered double hydroxide precursor (LDH, Ni 6 Al 2 (OH) 16 (CO 3 ) 0.75 (OH) 0.25 ·4H 2 O) are reported in this paper. In-situ X-ray adsorption spectroscopy shows that reduction of Ni from the LDH precursor to form a highly loaded 80% Ni–Al 2 O 3 catalyst (Ni–Al 2 O 3 –LDH) is faster than reduction of a 10% impregnated Ni–Al 2 O 3 alumina (Ni–Al 2 O 3 –I) catalyst. The reduced Ni–Al 2 O 3 –LDH catalyst exhibits highly dispersed Ni nanoparticles (3–5 nm) distributed on top, partially embedded nanoparticles, and some encapsulated in the Al 2 O 3 matrix. The nanoparticles impregnated on alumina (Ni–Al 2 O 3 –I) are larger (∼7–15 nm) and appear on top of the alumina support. Conversion vs time on stream (TOS) results during ethanol decomposition at 250 °C on Ni–Al 2 O 3 –LDH exhibits only a slight deactivation during 100 h TOS, while the Ni–Al 2 O 3 –I catalyst shows rapid deactivation with no conversion after 2 h TOS. X-ray photoelectron spectroscopy shows that the carbon content increases up to 48% after 100 h TOS on the Ni–Al 2 O 3 –LDH catalyst, while a similar increase occurs after 2 h TOS on the Ni–Al 2 O 3 –I catalyst . TEM shows that after 100 h TOS either a thin layer of amorphous carbon or carbon nanotubes forms on Ni on top of the alumina matrix and on partially embedded Ni nanoparticles on the Ni–Al 2 O 3 –LDH catalyst. Total surface area of the Ni–Al 2 O 3 –LDH catalyst increased during TOS, which may be suplying fresh surface Ni from the encapsulated Ni nanoparticles that sustain the high activity. [ABSTRACT FROM AUTHOR]

• Catalytic cracking of toluene with PDA porous carbon increases hydrogen production. • The concentration of activated steam has a positive influence on the surface area. • More C-O functional groups are more likely to have n-π interaction with toluene. Carbon-based metal catalysts have excellent catalytic performance due to their porous structure and high dispersion of metal particles. In this paper, polydopamine (PDA) microspheres as carbon supports and Fe as the metal phase are used to synthesize carbon-based nano-Fe catalysts for catalytic cracking of toluene. The PDA derived carbon-based metal catalysts has more regular spherical shape when compared with biomass derived catalyst. The effect of activation steam concentration and Fe load on the characteristics of catalyst have been studied. As the concentration of activated steam increases from 7.5% to 15%, the specific surface area of the carbon support increases significantly, and the number of micropores also increases. When the Fe impregnation concentration is less than 5%, the dispersion of the metal particles on the surface of the carbon support is very good, and when the Fe impregnation concentration is greater than 5%, the metal particles on the surface of the carbon support begin to agglomerate. The introduction of this catalyst can significantly increase the removal efficiency of toluene and the hydrogen content of tail gas. The carbon-based metal catalysts before and after the toluene catalytic cracking experiments are characterized and found that the microporous structure played an important role in the removal of toluene, and the C─O functional groups and ─OH groups on the catalyst surface also played an important role in the catalytic process. The addition of Fe species can increase the specific surface area and promote the formation of surface functional groups, and can also strengthen the π-π interaction and electrostatic interaction on the catalyst surface. The lattice oxygen introduced by iron oxide can provide oxygen source for the oxidation reaction of toluene. [ABSTRACT FROM AUTHOR]

Oily sludge (OS) from steel mills contains a large number of heavy components and has high viscosity. In this paper, the preparation of high value-added gas from the pyrolysis of OS catalyzed by calcined olivine (C-OL), xiuyan jade (C-XY), iddingsite (C-ID) and their nickel carrier was investigated. ICP-OES, SEM, EDX, XRF, and XRD were applied to characterize the catalysts. The effect of the catalyst on the pyrolysis of OS and the regulation mechanism of gas product quality were investigated. Thermogravimetric results showed that all the six catalysts could improve the total weight loss of OS, among which the addition of C-OL(Ni) increased by 11.58 wt%. Compared with the pyrolysis of OS, the production of H 2 increased by 82.65 and 23.49 mL after C-OL and C-XY were added at 900 °C, respectively. Ni ore-based catalysts can promote tar cracking, thereby producing more pyrolysis gas, in which the production of H 2 is significantly increased. The addition of C-XY(Ni) increased the production of H 2 by 239.29 mL. After nickel was loaded, the catalysts showed better catalytic activity at a high temperature. Results show that the nickel-loaded natural ore as catalyst can promote the pyrolysis of OS and can obtain pyrolysis gas with high added value. [Display omitted] • The catalytic pyrolysis of oily sludge was employed with six different catalysts. • Ni ore-based catalysts promoted pyrolysis of oily sludge to produce hydrogen. • Calcined-xiuyan jade loaded with Ni(C-XY(Ni)) showed the best catalytic ability. • After adding C-XY(Ni), the maximum gas yield was 1322 mL and the H 2 accounted for 45%. [ABSTRACT FROM AUTHOR]

The removal of biomass tar is the key technology in the pyrolysis and gasification technology, and the advantages of solid waste pyrolysis char in tar removal gradually become prominent. In this paper, the tar model compound (benzene) was catalytic reformed by a novel hybrid carrier catalysts using a laboratory dual-stage reactor. The hybrid carrier catalyst was prepared by wet impregnation method with nickel active substance, and the carrier was a two-material mixture of peat char and sludge char. In the reaction of steam reforming benzene, the effects of temperature (600–800 °C) and nickel load (5%–20%) on benzene conversion were investigated, showing that the catalyst have good benzene removal ability (91.8%) and the gas product with high syngas content (93.6%) was obtained. The surface properties of the catalyst was detected by SEM, EDS, BET and XRD detection, in order to prove that the catalytic performance was related to surface nanoparticles and abundant active sites. The novel hybrid carrier catalyst can effectively remove the aromatic tar and produce syngas with high performance. • A novel PC-SC based Ni catalyst was prepared for benzene removal. • The benzene conversion can reach 91.8% under the optimized conditions. • The as-synthesized catalysts show excellent selectivity for syngas (93.6%). • The active substance is present in the form of Ni and NiSi. • The selectivity for CO 2 increased gradually with the increase of time. [ABSTRACT FROM AUTHOR]

In this paper, a series of bimetallic palladium–iridium catalysts supported on active carbon (Pd–Ir/C) were prepared by the impregnation-reduction method. Effects of the composition on the performance and stability of bimetallic catalysts in the decomposition of HI were investigated. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area were employed to characterize their structure, morphology and surface area, respectively. The results of activity tests indicated that all the bimetallic Pd–Ir catalysts were more active than the monometallic 5% Pd/C and 5% Ir/C catalysts at both 400 °C and 500 °C. Among Pd, Ir and binary Pd–Ir catalysts, the 4% Pd–1% Ir/C was the most active for HI catalytic decomposition at 400 °C. Due to the low cost, high activity and good stability, the carbon supported bimetallic Pd–Ir catalysts are more potential candidates to replace Pt/C for HI decomposition in the IS thermochemical cycle. [ABSTRACT FROM AUTHOR]

The use of ceria–zirconia based catalysts in hydrogen production from simple alkanes and oxygenated hydrocarbons for the processes of steam reforming (SR), autothermal reforming (‘ATR’), catalytic partial oxidation (‘CPO’), and dry reforming (‘DR’) is reviewed in this paper. Along with preparation methods, the effects of operating conditions like molar steam to carbon ratio, oxygen to carbon ratio, and temperature on the performance of hydrogen production from methane, acetic acid, ethanol, and glycerol were examined. SR and ATR of these feedstocks over ceria–zirconia supports have been widely investigated. In comparison the utilization of these supports in the CPO and DR processes has been investigated mainly for methane as compared to oxygenated hydrocarbons. Ce-rich supports were reported to be effective in hydrogen production from SR and ATR of ethanol and glycerol and in steam methane reforming (SMR) in the ‘low’ temperature range (500–600°C), whereas zirconium-rich supports exhibited higher catalytic activity in the ‘high’ temperature range (700–800°C). In the case of DR, Ce-rich supports were effective at high temperatures i.e. above 700°C. The methods of preparation of the supports/catalyst are shown to affect the surface area (catalyst/support), crystallite size of (active metal/support), reducibility and dispersion of the active metal, thus affecting performance of the catalyst. [ABSTRACT FROM AUTHOR]

• NiO/NaF has universality for hydrogen production from OVOCs steam reforming. • OVOCs steam reforming over NiO/NaF is a rapid surface reaction process. • NaF can promote the efficient adsorption of OVOCs by NiO/NaF. • The local electric field generated by F- induces the weakening of the Ni-O bond. Regenerable NiO/NaF catalysts break the limitation that catalyst with low specific surface area is difficult to obtain high catalytic activity. In this paper, we investigated the feasibility and universal applicability of hydrogen evolution from different oxygen-containing volatile organic compounds (OVOCs) such as methanol, formaldehyde, formic acid, ethanol, acetic acid, acetone and ethyl acetate steam reforming over NiO/NaF catalysts. The reaction processes and catalytic mechanism of OVOCs steam reforming by 4 wt%NiO/NaF catalyst were analyzed by FESEM, H 2 -TPR, in situ DRIFTS, XRD characterization and Density functional theory (DFT) calculation. The results showed that different OVOCs could achieve high-efficiency hydrogen production in steam reforming over 4 wt%NiO/NaF catalyst. The order of conversion easiness was formic acid > formaldehyde > methanol > acetic acid > ethanol > acetone > ethyl acetate. Single-carbon organics such as formic acid, formaldehyde and methanol, had H 2 selectivity exceeding 100% at 350, 450 and 500 °C, respectively. The effective reforming temperature rose with the increasing of carbon contents of reactants. Further investigation confirmed that hydrogen production from different OVOCs steam reforming over 4 wt%NiO/NaF catalyst was a rapid surface reaction. And NaF played a key role, which not only promoted the adsorption of the catalyst to the reactants, but also generated local electric field induced by F- ion that weakened the Ni-O bond and reduced the activation energy. As a result, NiO/NaF had better low-temperature redox properties and hydrogen evolution performance than other nickel-based catalysts with big specific surface area. [ABSTRACT FROM AUTHOR]

Abstract: The water gas shift reaction (WGSR) is an attractive process for enhancing the conversion of syngas carbon monoxide contents into carbon dioxide and hydrogen by means of steam in medium- and small-scale coal gasification power plants integrated with Carbon Capture and Storage (CCS) technologies. Fixed bed gasifiers, in fact, may become an interesting solution for medium- and small-scale applications in distributed power generation, although a syngas with a low LHV (about 6–7MJ/kg), high N2 (40–45%) and low H2 content, is generated when air is used, as usual, as oxidant. Syngas LHV can be enhanced by using oxygen (or oxygen enriched air) instead of air. However, when oxygen is used an appropriate amount of diluent agent as additional steam, recirculated syngas or CO2 is fed into the gasifier to control gasification temperature. In the case of syngas recirculation, the gasification process produces a syngas characterized by a high CO2 content, suitable for a more efficient separation. This paper concerns the experimental investigation and numerical simulation of carbon monoxide conversion and hydrogen generation from WGSR, when high CO2 content operating mixtures are considered. A baseline mixture was assumed that simulates the fuel gas produced by coal gasification in a small-scale air-blown updraft gasifier. During the experiments the fraction of N2 in the baseline mixture was gradually replaced with increasing CO2 fraction in order to investigate its effects of CO2 concentration on reaction and catalysts performances. An experimental apparatus, designed and built at the Department of Mechanical Engineering of the University of Cagliari (DIMECA), was used to investigate the main performance of WGSR, using high CO2-content operating mixtures and different catalyst types (Fe/Cr or Pt/Al for high temperature and Cu/Zn or Pt/Al for low temperature), and varying fundamental parameters, such as residence time of reactants in the catalyst bed, reaction temperature and H2O/CO ratio. The experimental results are supported by an in-depth numerical analysis. Numerical simulations were carried out using zero-dimensional (CSTR-based equilibrium model), one-dimensional (PFR-based) and CFD two-dimensional computational models to characterize the spatial and time-dependent behavior of the process. [Copyright &y& Elsevier]

Abstract: This paper investigates a facile and one-step synthesis of trimetallic magnetic Cu@FeNi core–shell nanoparticles, which are composed of crystalline Cu cores and amorphous FeNi shells, at room temperature under ambient atmosphere within 2 min. It is found that among the Cu@FeNi system, Cu0.4@Fe0.1Ni0.5 shows the best synergistic performance for catalyzing the hydrolytic dehydrogenation of ammonia borane with the activation energy of 32.9 kJ/mol, being lower than most of the reported data, and the catalytic activity of Cu0.4@Fe0.1Ni0.5 is much better than its monometallic, bimetallic and trimetallic counterparts whether in states of pure metals, alloys or physical mixtures. Further, the present catalyst has a good recycle stability with an easy magnetic separation method. [Copyright &y& Elsevier]

Abstract: This paper explores the effect and siting (location) of Nafion on Pt/C as exists in a PEM fuel cell catalyst layer. The addition of 30wt% Nafion on Pt/C (Nfn-Pt/C) resulted in a severe loss of BET surface area by filling/blocking the smaller pore structures in the carbon support. Surprisingly, the presence of this much Nafion appeared to have only a minimal effect on the adsorption capability of either hydrogen or CO on Pt. However, the presence of Nafion doubled the amount of time required to purge most of the gas-phase and weakly-adsorbed hydrogen molecules away from the catalyst during hydrogen surface concentration measurements. This strongly chemisorbed surface hydrogen was determined by a H2/D2 switch and exchange procedure. Nafion had an even more pronounced effect on the reaction of a larger molecule like cyclopropane. Results from the modeling of cyclopropane hydrogenolysis in an idealized pores suggest that partial blockage of only the pore openings by the Nafion for the meso–macropores is sufficient to induce diffusion limitations on the reaction. The facts suggest that most of the Pt particles are in the meso–macropores of the C support, whereas Nafion is present primarily on the external surface of the C where it blocks significantly the micropores but only partially the meso–macropores. [Copyright &y& Elsevier]

Abstract: The major challenge of complex hydride for hydrogen storage is to release hydrogen at a moderate temperature with rapid kinetics. This paper reports a new composite system (NaBH4/ZnF2) to generate hydrogen at a low temperature below 100 °C. The NaBH4 and ZnF2 mixture was prepared by a mechanical milling in a 2:1 M ratio. Dehydrogenation of the mixture during a heating process shows that the initial dehydrogenation temperature was below 100 °C with favorable kinetics. The structural analysis confirmed the formation of NaBF4 and Zn in the reaction products. The study concerning the reaction mechanism reveals that ZnF2 plays a role of reagent rather than catalyst. The produced intermediate of NaZnF3, however, affects the decomposition of the emitted B2H6. This work suggests that the extension of the decomposition mechanism of NaBH4/ZnF2 composite system would favor the development of new catalysts for complex hydride systems. [Copyright &y& Elsevier]

Abstract: The present paper deals with the study on complete removal of CO in H2-rich gas stream through CO-SMET over Ru-based catalysts supported on γ-Al2O3 and CeO2 carriers. All the catalysts, loaded with 3% Ru, were prepared by a conventional impregnation method and their CO removal performance was determined at the powder level in a fixed bed micro reactor. The 3% Ru–γAl2O3 catalyst showed the best performance; consequently, it was deposited on microchannel metal plates reactor. With a catalyst load on the microchannel plates of 5mgcm−2 the performance was poor as complete CO conversion was not reached and also CO2 methanation was present. Increasing Ru load to 5%, the performance further worsened, the CO conversion decreased and higher amount of methane was produced. The catalytic activity on microchannel metal plates reactor was improved with the 3% Ru–γAl2O3 catalyst by doubling the its load on the surface (10mgcm−2): the residual CO concentration decreased to about 100–150ppmv at 310°C, but a large amount of methane was formed also by the CO2 methanation, thus reducing catalyst selectivity. [Copyright &y& Elsevier]

Abstract: Over the past couple of years, the resurgence of placing an effective and sustainable amendment to combat against the auxiliary industrial entities, remains a highly contested agenda from a global point. With the renaissance of activated carbon, there has been a steadily growing interest in the research field. Recently, the adoption of zeolite composite, a prestigious advanced catalyst which formulates the enhancement of adsorption rate and hydrogen storage capability, has fore fronted to be a new growing branch in the scientific community. Confirming the assertion, this paper presents a state of art review of activated carbon/zeolite composite technology, its fundamental background studies, and environmental implications. Moreover, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbon/zeolite composite represents a potentially viable and powerful tool, leading to the plausible improvement of environmental preservation. [Copyright &y& Elsevier]

Abstract: This paper deals with self-ignition of catalytic microburners from ambient cold-start conditions. First, reaction kinetics for hydrogen combustion is validated with experimental results from the literature, followed by validation of a simplified pseudo-2D microburner model. The model is then used to study the self-ignition behavior of lean hydrogen/air mixtures in a Platinum-catalyzed microburner. Hydrogen combustion on Pt is a very fast reaction. During cold start ignition, hydrogen conversion reaches 100% within the first few seconds and the reactor dynamics are governed by the “thermal inertia” of the microburner wall structure. The self-ignition property of hydrogen can be used to provide the energy required for propane ignition. Two different modes of hydrogen-assisted propane ignition are considered: co-feed mode, where the microburner inlet consists of premixed hydrogen/propane/air mixtures; and sequential feed mode, where the inlet feed is switched from hydrogen/air to propane/air mixtures after the microburner reaches propane ignition temperature. We show that hydrogen-assisted ignition is equivalent to selectively preheating the inlet section of the microburner. The time to reach steady state is lower at higher equivalence ratio, lower wall thermal conductivity, and higher inlet velocity for both the ignition modes. The ignition times and propane emissions are compared. Although the sequential feed mode requires slightly higher amount of hydrogen, the propane emissions are at least an order of magnitude lower than the other ignition modes. [ABSTRACT FROM AUTHOR]

Abstract: Selenium is a trace element of concern in several geochemical contexts, due to the potentially high mobility of the selenium oxyanions and the narrow range between deficiency and toxicity of the element. For high level nuclear waste repositories the long-lived fission product 79Se has been identified as a potential key dose contributor for the long-term safety. This paper deals with the catalytic effect of Pd(s) on the H2 reduction of selenium oxyanions which was studied experimentally in aqueous solutions containing bicarbonate and chloride. Pd-catalysts and hydrogen have been proposed for the remediation of various groundwater contaminants and can also serve as a model substance for catalytic noble metal inclusions present in spent nuclear fuel. In this study selenite (SeO3 2−) was found to adsorb on Pd. In the presence of hydrogen the rate of selenite removal increased yielding elemental Se. However, no adsorption or reduction of selenate (SeO4 2−) was observed. A simple radiation chemical experiment revealed a notable barrier towards stepwise one-electron reduction of selenate to selenite. This provides an explanation for the lower reactivity of selenate in systems where reductive immobilization of selenite as well as selenate is thermodynamically favorable. [Copyright &y& Elsevier]

Abstract: This paper deals with the preparation (by solution combustion synthesis, SCS), characterization (by XRD, BET, FESEM and TPD/R analyses), catalytic activity evaluation (in a temperature-programmed reaction—TPRe apparatus), and the assessment of the reaction mechanism of NO reduction by H2 in the presence of oxygen on a series of perovskite-type catalysts belonging to the LaFeO3 family (LaFeO3, La0.8Sr0.2FeO3, Pd/La0.8Sr0.2FeO3, La0.8Sr0.2Fe0.9Pd0.1O3, La0.7Sr0.2Ce0.1FeO3, Pd/La0.7Sr0.2Ce0.1FeO3, La0.7Sr0.2Ce0.1Fe0.9Pd0.1O3). The catalysts have been studied in the 25–350°C temperature range. Significant catalytic activities were measured at 150–250°C. Among the catalysts screened, La0.8Sr0.2Fe0.9Pd0.1O3, showed the best performance. Hence, it was deposited directly over a ceramic honeycomb monolith by in situ SCS and then tested in a lab-scale test rig. A mechanistic analysis is presented concerning the relationship between the observed activity and the reducibility of the B site, determined from TPR experiments, as well as the correlation between the observed oxygen inhibition and the proposed NO x reduction mechanism. Some final conclusions are drawn on the perspective of the practical application of the investigated after-treatment route for diesel exhaust gases. [Copyright &y& Elsevier]

Abstract: The hydrogen storage properties, phase components and surface characteristics of a newly designed MgH2–(Sr,Ca)2AlH7 composite doped with a little amount of TiF3 were studied in this paper. It was found that the MgH2–30wt.% (Sr,Ca)2AlH7 composite doped with 2mol% of TiF3 desorbed hydrogen quickly at 573K. Moreover, it has a higher re-hydrogenation rate at the temperatures below 473K under the hydrogen pressure of 1.0MPa. The new Ti-contained species as well as the phases (Sr,Ca)F2, (Sr,Ca)H2 and (Sr,Ca)Al4 formed during the dehydrogenation process prior to the hydrogen uptake distributes homogeneously on the surface of Mg particles, and has a good catalytic effect on the re-hydrogenation process of Mg phase consequently. [Copyright &y& Elsevier]

Abstract: The production of alternative fuels such as biodiesel and ethanol has increased over the last few years. Such fuels are vital for the reduction of energy dependence on foreign countries and to protect the environmental damage associated with the use of fossil fuels. Due to the increased production of biodiesel, a glut of crude glycerol has resulted in the market and the price has plummeted over the past few years. Therefore, it is imperative to find alternative uses for glycerol. A variety of chemicals and fuels including hydrogen can be produced from glycerol. Hydrogen is produced by using several processes, such as steam reforming, autothermal reforming, aqueous-phase reforming and supercritical water reforming. This paper reviews different generation methods, catalysts and operating conditions used to produce hydrogen using glycerol as a substrate. Most of the studies were focused on hydrogen production via steam reforming process and still less work has been done on producing hydrogen from crude glycerol. [Copyright &y& Elsevier]

Abstract: The environmental issues, due to the global warming caused by the rising concentration of greenhouse gases in the atmosphere, require new strategies aimed to increase power plants efficiencies and to reduce CO2 emissions. This two-paper work focuses on a different approach for capture and reduction of CO2 from flue gases of fossil fired power plant, with respect to conventional post-combustion technologies. This approach consists of flue gases utilization as co-reactants in a catalytic process, the tri-reforming process, to generate a synthesis gas suitable in chemical and energy industries (methanol, DME, etc.). In fact, the further conversion of syngas to a transportation fuel, such as methanol, is an attractive solution to introduce near zero-emission technologies (i.e. fuel cells) in vehicular applications. In this Part A, integrated systems for co-generation of electrical power and synthesis gas useful for methanol production have been defined and their performance has been investigated considering different flue gases compositions. In Part B, in order to verify the environmental advantages and energy suitability of these systems, their comparison with conventional technology for methanol production is carried out. The integrated systems (ITRPP, Integrated Tri-Reforming Power Plant) consist of a power island, based on a thermal power plant, and a methane tri-reforming island in which the power plants'' exhausts react with methane to produce a synthesis gas used for methanol synthesis. As power island, a steam turbine power plant fuelled with coal and a gas turbine combined cycle fuelled with natural gas have been considered. The energy and environmental analysis of ITRPP systems (ITRPP-SC and ITRPP-CC) has been carried out by using thermochemical and thermodynamic models which have allowed to calculate the syngas composition, to define the energy and mass balances and to estimate the CO2 emissions for each ITRPP configuration. The repowering of the base power plants (steam turbine power plant and gas turbine combine cycle) is very high because of the large amount of steam produced in the tri-reforming island (in the ITRPP-SC is about of 64%, while in the ITRPP-CC is about of 105%). The reduction in the CO2 emissions has been estimated in 83% (15.4 vs. 93.4 kg/GJFuelinput) and 84% (8.9 vs. 56.2 kg/GJFuelinput) for the ITRPP-SC and ITRPP-CC respectively. [Copyright &y& Elsevier]

Abstract: Solid oxide fuel cells (SOFCs) constitute an attractive power-generation technology that converts chemical energy directly into electricity while causing little pollution. NanoDynamics Energy (NDE) Inc. has developed micro-tubular SOFC-based portable power generation systems that run on both gaseous and liquid fuels. In this paper, we present our next generation solid oxide fuel cells that exhibit total efficiencies in excess of 60% running on hydrogen fuel and 40+% running on readily available gaseous hydrocarbon fuels such as propane, butane etc. The advanced fuel cell design enables power generation at very high power densities and efficiencies (lower heating value-based) while reforming different hydrocarbon fuels directly inside the tubular SOFC without the aid of fuel pre-processing/reforming. The integrated catalytic layered SOFC demonstrated stable performance for >1000h at high efficiency while running on propane fuel at sub-stoichiometric oxygen-to-fuel ratios. This technology will facilitate the introduction of highly efficient, reliable, fuel flexible, and lightweight portable power generation systems. [Copyright &y& Elsevier]

Abstract: One of the major problems facing mankind in 21st century is the global warming which is induced by the increasing concentration of carbon dioxide and other greenhouse gases in the atmosphere. One of the most promising processes for controlling the atmospheric CO2 level is conversion of CO2 to methanol by catalytic hydrogenation. In this paper, the conversion of CO2 in a membrane dual-type methanol synthesis reactor is investigated. A dynamic model for this methanol synthesis reactor was developed in the presence of long-term catalyst deactivation. This model is used to compare the removal of CO2 in a membrane dual-type methanol synthesis reactor with a conventional dual-type methanol synthesis reactor. A conventional dual-type methanol synthesis reactor is a vertical shell and tube heat exchanger in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual-type methanol synthesis reactor, the wall of the tubes in the conventional gas-cooled reactor is covered with a palladium–silver membrane, which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. The proposed dynamic model was validated against measured daily process data of a methanol plant recorded for a period of 4 years and a good agreement was achieved. [Copyright &y& Elsevier]