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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]

The synthesis of a 90% Ni/Al2O3 catalyst via solution combustion synthesis with various fuels was studied in this work. Catalysts with a high content of the active component (i.e., nickel) were obtained as a result of the combustion of Ni(NO3)2·6H2O and Al(NO3)3·9H2O mixtures with fuel. The fuels, such as hexamethylenetetramine, glycine, urea, starch, citric acid, and oxalic acid, were investigated. The synthesis was carried out in a furnace, with the temperature being raised from room temperature to 450 °C at a rate of 1 °C per min. The paper evaluates the efficiency of fuels and their effect on the structure and properties of catalysts, as well as their catalytic activity. The catalyst was used for the synthesis of hydrogen and carbon nanofibers by methane decomposition at 1 bar and 550 °C. The catalysts were tested in a vertical flow reactor without preliminary reduction. The obtained samples of catalysts and carbon nanomaterials were studied by transmission electron microscopy, low-temperature nitrogen adsorption, and X-ray diffraction. The highest activity of the catalyst was obtained when citric acid was used as a fuel. The specific yields of hydrogen and carbon nanofibers were 17.1 mol/gcat and 171.3 g/gcat, respectively. Catalytic decomposition of methane led to the formation of cup-stacked carbon nanofibers. [ABSTRACT FROM AUTHOR]

It was the constant pursuit of researchers to explore catalysts with higher catalytic activity, and the use of co-catalysts to modify the performance of photocatalytic materials had a significant effect on charge separation. In this paper, the non-precious metal NiS-modified ZnCo2O4 composite catalytic material prepared by hydrothermal method had high-efficiency catalytic performance. When the weight ratio of NiS to ZnCo2O4 was 12%, the optimal catalytic activity is 3.57 mmol g−1 h−1, which was more than twice that of ZnCo2O4. The presence of NiS not only improved the specific surface area of the catalyst and its ability to respond to light, but the close interface formed by the combination of the two monomer phases accelerated the transfer and the utilization of the photocharge on ZnCo2O4 to NiS, thereby promoting the separation of electron holes and improving the photocatalytic activity of the catalyst. According to the research results, the mechanism of hydrogen production in the photocatalytic system was revealed. In this paper, NiS was used to modify the bimetallic oxide with cubic appearance, which provided a new strategy for the development of new photocatalysts. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) is a complex reaction involving many interdependent physicochemical steps. Highly ordered carbon nitride‐based materials, such as Na‐PHI and K‐PHI, display some of the highest activities for H2 evolution among the carbon nitride‐based materials, due to their electronic properties, but also the presence of cyanimide terminations, which favors the charge transfer for the Pt cocatalyst nanoparticles (NPs). For such highly optimized semiconductor structures, the necessity to control and improve other steps of the photocatalytic process becomes essential, in particular the poor electron transfer from the Pt NPs to the protons in solution over the Helmholtz or Stern layer. Taking highly ordered Na‐PHI as a test material, the influence of water‐dissolved alkali cations on the HER is systematically studied and it is experimentally verified that the electron transfer from the Pt NPs to the protons in solution limits the efficiency of heterogeneous carbon nitride‐based catalysts. This paper explains how hydrated alkali cations influence electron transfer and are able to boost the H2 evolution rate of the same Na‐PHI from 2401 up to 5330 µmol h−1 g−1 with an apparent quantum yield of 13% at 420 nm. [ABSTRACT FROM AUTHOR]

Steam reforming (SR) of bio-oil has been considered as one of the promising methods for hydrogen production. In this paper, cerium modified Ni/Attapulgite (ATP) catalysts were successfully synthesized by traditional chemical precipitation method and utilized for SR of various bio-oil derived oxygenated model compounds. The effect of Ce content on the structural properties of Ni/ATP was investigated by ICP-OES, N2 adsorption–desorption, XRD, H2-TPR and HRTEM characterizations. The results exhibited that 10Ce–Ni/ATP catalyst had the strongest metal-support interaction and highly dispersion of Ni species with smallest particle size of 6.21 nm. Therefore, it presented the maximum ethanol conversion of 97.21% and H2 yield of 83.15% at relative lower reaction temperature 500 °C during 4 h of SR of ethanol (SRE). In addition, it unfolded promising performance for SR of acetic acid (SRAA) and acetone (SRA). Furthermore, the influence of different oxygenates on the amount and nature of carbon deposits in used 10Ce–Ni/ATP catalyst was revealed by TG and Raman analyses. It found that the types of feedstock significantly affected the carbon species and amount and the formation of graphic layers around the Ni metal sites was the mainly factor for rapid deactivation of 10Ce–Ni/ATP during 4 h of SRA reaction. [ABSTRACT FROM AUTHOR]

Recently, hydrogen is utilized by numerous chemical industries as an alternate over non-renewable fuels, and surely it will be considered as an important fuel in the near future. This paper reports a review of various reforming technologies for hydrogen production from butanol produced by fermentation of feedstocks like wheat, sugar beets, sugar cane, etc. with a number of aspects involving selection of an appropriate catalyst to suppress undesirable products as many reforming reactions are dependent on the catalyst properties to enhance the formation of significant fuels which may fulfill the future energy needs. An overview of butanol reforming processes with experimental and theoretical studies in order to grasp possibilities and restrictions of these processes is not comprehensively presented yet. In this paper, an assessment of published articles in brief related to essential parameters to carry out a pertinent research in the future is presented for the advancement of fuel processing technologies. [ABSTRACT FROM AUTHOR]

Synthesis of catalysts with high activity for hydrogen evolution reaction (HER) has been a hot topic in electrocatalysis. In this paper, using MIL-88A(Fe) metal-organic complex, polyoxometalate (POM) and H2PtCl6 as starting materials, hierarchic and low Pt0-loading micro-rods (denoted as Pt-POMFe, i.e. Pt-PW12Fe or Pt-PMo12Fe) have been synthesized, in which the Pt0 nanoparticles can be stabilized by POM. The Pt-PW12Fe micro-rod containing [PW12O40]3- polyoxoanion component (0.30% Pt0-loading) which retains the spindle structure of its parent MIL-88A(Fe) exhibits a low overpotential of 28 mV at current density of 10 mA·cm−2 for HER that is close to the electrocatalytic effect of commercial Pt/C (ca. 20% Pt0-loading). Such high electrocatalytic reactivity is mainly caused by the synergistic effect of the three components of POM, Pt0, and Fe3O4@C. The structure effectively increases the active sites of the catalyst and improves its conductivity and stability. The Pt-POMFe catalyst extends a new family of MOF-POM functional materials and provides a new concept to the design and synthesis of highly-efficient and low-cost electrocatalyst for hydrogen production. [ABSTRACT FROM AUTHOR]

Highlights: This review systematically summarizes the source of electricity, the key choice of catalyst, and the potentiality of electrolyte for prospective hydrogen generation. Each section provides comprehensive overview, detailed comparison and obvious advantages in these system configurations. The problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. Green hydrogen from electrolysis of water has attracted widespread attention as a renewable power source. Among several hydrogen production methods, it has become the most promising technology. However, there is no large-scale renewable hydrogen production system currently that can compete with conventional fossil fuel hydrogen production. Renewable energy electrocatalytic water splitting is an ideal production technology with environmental cleanliness protection and good hydrogen purity, which meet the requirements of future development. This review summarizes and introduces the current status of hydrogen production by water splitting from three aspects: electricity, catalyst and electrolyte. In particular, the present situation and the latest progress of the key sources of power, catalytic materials and electrolyzers for electrocatalytic water splitting are introduced. Finally, the problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. It is expected that this review will have an important impact on the field of hydrogen production from water. [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]

The thermal degradation and conversion of waste polyethylene (PE) using a two‐step process including hydrothermal oxidation (HO) and aqueous phase reforming (APR) were investigated. The objective of this study was to achieve efficient disposal of waste PE and generate H2 in a mild and green way. The effects of various HO conditions on both HO and APR processes were studied. A high H2O2 concentration caused overoxidation of PE resulting in more CO2. Decreasing the H2O2 concentration weakened the overoxidation. The process using diluted H2O2 exhibited the highest selectivity for acetic acid among the produced carboxylic acids. When the HO temperature exceeded 200 °C, there was an increase in the CO2 yield during the HO process and a decrease in the H2 yield during the APR process. In addition, the effects of various monometallic and bimetallic catalysts on the reforming of the aqueous phase from the HO of PE were discussed. The highest H2 mole fraction (51.52 %) in gaseous products from the APR process was obtained with Ru/mesoporous carbon. Nevertheless, Ru−Ni exhibited a higher stability than the monometallic Ru catalyst. [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]

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]

The electrolytic water method is an outstanding hydrogen production process because of its high stability and no restriction. A low-priced and efficient catalyst for electro-deposition of Ni–Co microspheres and nanoclusters on carbon steel (Ni–Co/CS) has been prepared by the dynamic hydrogen bubble template. In the 6 M KOH solution, Ni–Co/CS only requires an overpotential of 48 mV to provide a current density of 50 mA cm−2. At the same time, it also has a large electrochemically active specific surface area (ECSA) and a hydrophilic surface. In addition, the study about the influence of carbon steel (CS) on Ni–Co coatings and the comparison experiment for different base materials has been completed. The results prove that CS is an excellent base material for hydrogen production. It can help the Ni–Co catalyst to have a stable electrolysis in 6 M KOH for 500 h. The above properties of Ni–Co/CS catalyst make it a new choice of hydrogen production by electrolysis of water in practical applications. [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]

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]

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]

Molecular ruthenium cyclopentadienone complexes were employed for the first time as pre‐catalysts in the homogeneously catalysed Aqueous Phase Reforming (APR) of glucose. Shvo's complex resulted the best pre‐catalyst (loading 2 mol %) with H2 yields up to 28.9 % at 150 °C. Studies of the final mixture allowed to identify the catalyst's resting state as a mononuclear dicarbonyl complex in the extracted organic fraction. In situ NMR experiments and HPLC analyses on the aqueous fraction gave awareness of the presence of sorbitol, fructose, 5‐hydroxymethylfurfural and furfural as final fate or intermediates in the transformations under APR conditions. These results were summarized in a proposed mechanism, with particular emphasis on the steps where hydrogen was obtained as the product. Benzoquinone positively affected the catalyst activation when employed as an equimolar additive. [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]

This paper presents a numerical and experimental study on the performance of a methanol steam reformer integrated with a hydrogen/air combustion reactor for hydrogen production. A CFD-based 3D model with mass and momentum transport and temperature characteristics is established. The simulation results show that better performance is achieved in the cross-U type reactor compared to either a tubular reactor or a parallel-U type reactor because of more effective heat transfer characteristics. Furthermore, Cu-based micro reformers of both cross-U and parallel-U type reactors are designed, fabricated and tested for experimental validation. Under the same condition for reforming and combustion, the results demonstrate that higher methanol conversion is achievable in cross-U type reactor. However, it is also found in cross-U type reactor that methanol reforming selectivity is the lowest due to the decreased water gas shift reaction under high temperature, thereby carbon monoxide concentration is increased. Furthermore, the reformed gas generated from the reactors is fed into a high temperature proton exchange membrane fuel cell (PEMFC). In the test of discharging for 4 h, the fuel cell fed by cross-U type reactor exhibits the most stable performance. [ABSTRACT FROM AUTHOR]

Hydrogen is a clean renewable energy with potential for future environmental sustainability. The main challenge in hydrogen production via methanol steam reforming (MSR) is carbon monoxide (CO) formation that deactivates the catalyst. In this study, the effect of zinc (Zn) and cerium (Ce) on copper–mesoporous carbon (MC)-catalyst (Cu–MC) for MSR was investigated. The highest surface area (380.5 m2/g), observed for the Cu–MC prepared by one-pot (OP), decreased after incorporation of Ce and Zn. The temperature programmed reduction (H2-TPR) studies showed a decrease in the reduction temperature of CuO. The metal oxides were well distributed over the MC support based on scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. The MSR studies yielded methanol conversion of 65 and 68% for Ce-loaded Cu–MC prepared by OP and wet-impregnation (WI) methods at 300 °C and 250 °C, respectively. Addition of Zn to Cu–MC decreased methanol conversion, significantly, to 46%, at 300 °C. Both catalysts showed higher hydrogen selectivity, > 90%, with a lower CO selectivity for the Zn–Cu–MC catalyst. The Ce–Cu–MC (WI) catalyst showed good stability for 42 h with high H2 selectivity, > 90%, and methanol conversion of 40% at 250 °C. [ABSTRACT FROM AUTHOR]

By introducing Mg, Cu, Zn, Sn, and Mn into the synthesis processes of Ni and Al based hydrotalcite, Ni–Al layered hydrotalcite-derived catalysts with different metal compositions were prepared. In this paper, the effect of metal composition on the structure of Ni–Al layered hydrotalcite-derived catalysts is investigated, and then catalytic activities of prepared catalysts with different metal compositions on ethylene glycol aqueous-phase reforming are analyzed. The physicochemical properties of the Ni–Al layered hydrotalcite-derived catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), and nitrogen adsorption–desorption technology. The obtained hydrotalcite-derived catalysts were applied to the process of ethylene glycol aqueous-phase reforming (APR). The XRD results confirmed that the precursors of hydrotalcite-derived catalysts with metal compositions of Ni/Mg/Al, Ni/Cu/Al, Ni/Zn/Al, and Ni/Sn/Al had hydrotalcite crystalloid morphology. During the process of ethylene glycol aqueous phase reforming, all the catalysts showed high conversion of ethylene glycol (>90%), and the optimum hydrogen yield (73.5%) was obtained when using the catalyst with metal composition of Ni/Mg/Al at 225 °C under 2.6 MPa in nitrogen atmosphere for 2.5 h. [ABSTRACT FROM AUTHOR]

Green hydrogen production via electrocatalytic water splitting paves the way for renewable, clean, and sustainable hydrogen (H2) generation. H2 gas is produced from the cathodic hydrogen evolution reaction (HER), where the reaction is catalyzed primarily from Pt-based catalysts under both acidic and alkaline environments. Lowering the loading of Pt and the search for alternative active catalysts for HER is still an ongoing challenge. Two-dimensional MXenes are effective supports to stabilize and homogenously distribute HER-active electrocatalysts to boost the HER performance. Factors involved in the effectiveness of MXenes for their role in HER include transition metal types and termination groups. Recently, tailoring the conditions during the synthesis of MXenes has made it possible to tune the morphology of MXenes from multilayers to few layers (delaminated), formation of porous MXenes, and those with unique crumpled and rolled structures. Changing the morphology of MXenes alters the surface area, exposed active sites and accessibility of electrolyte materials/ions to these active sites. This review provides insight into the effects of varying morphology of MXenes towards the electrocatalytic HER activity of the MXene itself and MXene composites/hybrids with HER-active catalysts. Synthesis methods to obtain the different MXene morphologies are also summarized. [ABSTRACT FROM AUTHOR]

A novel Zn−Fe flow battery featuring an Fe3+ reduction reaction (Fe3+RR)‐coupled zinc oxidation, and an Fe2+ oxidation reaction (Fe2+OR)‐coupled hydrogen evolution reaction (HER) system as well, was established. This battery is capable of driving two Fe2+OR‐coupled HER systems in series based on the above Fe2+/Fe3+ cycling, for efficient self‐powered hydrogen evolution. Meanwhile, this Fe2+/Fe3+ cycling enables the preparation of a multifunctional catalyst, Pt‐3@SXNS (siloxene nanosheet), by the Fe2+OR‐promoted dispersion of Pt nanoparticles on SXNS; alternatively, this support could be obtained by Fe3+RR‐assisted exfoliation using Fe3+ from the anolyte of Fe2+OR‐coupled HER. The Pt‐3@SXNS catalyst exhibits excellent catalytic activities toward Fe3+RR in the Zn−Fe flow battery, HER, and Fe2+OR in the electrolyzer, which is attributed to the strong electronic interaction between Pt and Si. This work offers a new strategy for energy storage and low‐cost hydrogen production from acidic wastewater. [ABSTRACT FROM AUTHOR]

Rising energy needs and the exhaustion of fossil fuels are calling for renewable fuels such as dihydrogen (H2), commonly named 'hydrogen.' Biomass treatment produces glycerol, which can be further used to generate dihydrogen or syngas. Here, actual challenges comprise the design of efficient and economically viable catalysts for attaining high hydrogen yield and minimizing coke deposition. Here, we review glycerol valorization routes for hydrogen or syngas generation, such as pyrolysis, steam reforming, aqueous phase, dry, supercritical water, partial oxidation, and autothermal reforming. We focus on cobalt-based catalysts due to their high availability, low cost, thermal stability, and coke resistance. The efficiency of cobalt-based catalysts can be improved by modifying textural properties, particle size and distribution, the strength of metal–support interaction, surface acidity and basicity, oxygen mobility, and reducibility. Such improvements have led to 100% glycerol conversion, 90% dihydrogen yield, and coke deposition of about 0.05%. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H2 production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H2 production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H2 production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H2 production, identifying the promising applications of controlled nanomaterials. [ABSTRACT FROM AUTHOR]

Producing hydrogen via water electrolysis could be a favorable technique for energy conversion, but the freshwater shortage would inevitably limit the industrial application of the electrolyzers. Being an inexhaustible resource of water on our planet, seawater can be a promising alternative electrolyte for industrial hydrogen production. However, many challenges are hindering the actual application of seawater splitting, especially the competing reactions relating to chlorine at the anode that could severely corrode the catalysts. The execution of direct seawater electrolysis needs efficient and robust electrocatalysts that can prevent the interference of competing reactions and resist different impurities. In recent years, researchers have made great advances in developing high-efficiency electrocatalysts with improved activity and stability. This review will provide the macroscopic understanding of direct seawater splitting, the strategies for rational electrocatalyst design, and the development prospects of hydrogen production via seawater splitting. The nonprecious metal-based electrocatalysts for stable seawater splitting and their catalytic mechanisms are emphasized to offer guidance for designing the efficient and robust electrocatalyst, so as to promote the production of green hydrogen via seawater splitting. [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]

Glycerol (a bio-waste generated from biodiesel production) has been touted as a promising bio-syngas precursor via reforming route. Previous studies have indicated that carbon deposition is the major performance-limiting factor for nickel (Ni) catalyst during glycerol steam reforming. In the current paper, dry (CO2)-reforming of glycerol, a new reforming route was carried out over alumina (Al2O3)-supported nonpromoted and lanthanum-promoted Ni catalysts. Both sets of catalysts were synthesized via wet coimpregnation procedure. The physicochemical characterization of the catalyst showed that the promoted catalyst possessed smaller metal crystallite size, hence higher metal dispersion compared to the virgin Ni/Al2O3 catalyst. This was also corroborated by the surface images captured by the FESEM analysis. In addition, BET surface area measurement gave 92.05m2/g for non-promoted Ni catalyst whilst promoted catalysts showed an average of 1 to 6% improvement depending on the La loading. Reaction studies at 873 K showed that glycerol dry reforming successfully produced H2 with glycerol conversion and H2 yield that peaked at 9.7% and 25% respectively over 2wt% La content. The optimum catalytic performance by 2%La-Ni/Al2O3 can be attributed to the larger BET surface area and smaller crystallite size that ensured accessibility of active catalytic area. [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]

Electrochemical hydrogen production is considered as one of the most significant ways to develop clean energy in the future. Herein, the self‐supporting electrocatalyst of MoS2@Ni(Mn)VOX is fabricated on 3D nickel foam (NF) by a facile two‐step electrodeposition approach. The optimal MoS2@Ni(Mn)VOX electrode shows an ultralow overpotential of 61 mV to achieve a current density of 10 mA cm−2 and a Tafel slope of 35.1 mV dec−1 in 1 m KOH, which is superior to NF, MoS2@NF, NiVOX, Ni(Mn)VOX, or MoS2@NiVOX. The uniformly dispersed coral‐shaped heterostructure exposes more active sites and makes the charge transfer rate faster. The outstanding synergistic effect of MoS2 and transition metal oxides of Ni, Mn, and V also contribute to the enhanced activity of the catalyst. Benefiting from these, MoS2@Ni(Mn)VOX shows superior alkaline hydrogen evolution reaction activity and long‐term stability. Herein, a novel catalyst for highly efficient hydrogen evolution in alkaline media is provided. [ABSTRACT FROM AUTHOR]

Some tungsten catalysts of interest that are synthesized are bismuth tungstate (BT) and Tetrabutylammonium decatungstate (TBADT), using two consolidated procedures. BT is used as a photo-catalyst for the simulated solar light degradation of ofloxacin (OFL) antibiotic under relevant real conditions (µg L−1, fresh water) with the limit of 0.05 g L−1 of catalyst. A quantitative drug decomposition occurred following a bi-exponential first-order law, with an efficiency comparable with the most used P25 TiO2 catalyst. The photocatalytic profiles of OFL at µg L−1 and mg L−1 were monitored by high-pressure liquid chromatography (HPLC) coupled with fluorescence (FD) and ultraviolet (UV) detectors. Additionally, the main photoproducts were identified by high-pressure liquid chromatography coupled to electrospray ionization in tandem with mass spectrometry (HPLC-ESI-MS/MS). The catalyst Tetrabutylammonium decatungstate (TBADT) was used as a catalyst to produce hydrogen from glucose and 2-propanol in aqueous solution, providing hydrogen gas evolution up to 10 µmol g−1 h−1. [ABSTRACT FROM AUTHOR]

Summary: In this study, pomegranate peel (PP) waste was used as an efficient, cost‐effective, and metal‐free catalyst for the methanolysis reaction of sodium borohydride (NaBH4); furthermore, the prepared active material was utilized as a supercapacitor for electricity storage. The effect of several parameters, such as different acid concentrations, burning temperature, and burning times on the catalytic performance of the pomegranate peel catalyst (PP‐H3PO4‐Cat) were examined. Under optimum conditions, the most active catalyst was obtained by burning with 7 M phosphoric acid (H3PO4) solution at 400°C for 45 minutes. The maximum hydrogen generation rate (HGR) obtained from the methanolysis reaction of NaBH4 at 30°C and 60°C was found as 57 200 and 76 228 mL min−1 gcat−1, respectively. The activation energy value for the catalytic methanolysis reaction was calculated as 7.89 kJ mol−1. Furthermore, Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma ‐ optical emission spectrometry (ICP‐OES), X‐ray diffractometer spectroscopy (XRD), Brunauer‐Emmett‐Teller (BET), and scanning electron microscope (SEM) analyses were performed for characterization of the synthesized catalyst. The gravimetric capacitance of the prepared electrode (catalyst material with best results) was calculated as 29 F/g at 0.25 A/g current density. The electrodes made from biomass waste are both cheap and have a good capacity. [ABSTRACT FROM AUTHOR]

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: This paper investigated the production of hydrogen from methane under atmospheric pressure using a plasma–catalyst hybrid converter with emphasis on energy conservation. A spark discharge was used to ionize the hydrocarbon fuel and air mixture with a catalyst to enhance hydrogen production using two energy saving schemes, namely, heat recycling and heat insulation. The experimental results showed that higher methane feeding rate resulted in higher reformate gas temperature and a corresponding increase in methane conversion efficiency. The energy saving systems also enabled the oxygen/carbon ratio to be decreased to reduce oxidation of hydrogen and carbon monoxide and thereby improving the concentrations of hydrogen and carbon monoxide. By heat recycling, a lower methane feeding rate showed an 8.7% improvement in methane conversion efficiency whilst improvement was not apparent with higher methane supply rates due to the already high conversion efficiency. Moreover, it was shown that hydrogen production increased significantly with the reaction from water–gas shifting under the same operation parameters but with high methane selectivity. The best combination resulting in a total thermal efficiency of 77.11% was 10L/min methane feeding rate and 0.8O2/C ratio. With water–gas shifting (S/C ratio=0.5), an 86.26% hydrogen yield, equating to 17.25L/min hydrogen production rate could be achieved. The equilibrium production rate was calculated using the commercialized HSC Chemistry software (©ChemSW Software, Inc.). Good correlation was obtained between the calculations and the experimental results. [Copyright &y& Elsevier]

This paper focuses on the effect of Ru and Rh addition to SiO2-supported Co catalysts for the oxidative steam reforming of ethanol to produce hydrogen. Catalysts were tested in the reaction at atmospheric pressure and 623–673 K and characterized by X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and infrared spectroscopy with CO as the probe molecule. A synergistic effect between Co and Rh or Ru was seen in the oxidative steam reforming of ethanol. A study of the deactivation/regeneration of catalysts found that an oxidizing treatment recovered the performance of deactivated bimetallic catalysts. This process could be used in cycles to optimize both ethanol conversion and selectivity toward hydrogen production. [Copyright &y& Elsevier]

On board hydrogen production out of hydrocarbons (reforming) for fuel cells feed is subject to problems when used with traditional catalysts. High device weight, a relatively long transient time and poisoning problems make the integration onboard a vehicle complex. In response to these challenges, hydrocarbons reforming processes assisted by non-thermal plasmas for hydrogen production have been implemented over recent years. This paper aims to provide an overview of the setting up, feasibility and efficiency of the existing technologies here investigated. This state-of-the-art technology review explains the key characteristics of plasma reforming through various original approaches. The performances of some of the systems are then compared against each other and discussed. [Copyright &y& Elsevier]

The paper presents a novel technique that enhances the hydrogen yield of conventional biomass steam gasification. This is done by integrating the gasification and absorption reactions. The method involves steam gasification of a carbonaceous fuel (biomass) in presence of a sorbent. Experiments were conducted by gasifying pine bark in presence of calcium oxide. The gasification was carried out at atmospheric pressure in the temperature range . The hydrogen yield, total gas yield and carbon conversion efficiency increased by 48.6%, 62.2% and 83.5%, respectively, in the presence of sorbent at a gasification temperature of . This was attributed to the reforming of tars and hydrocarbons in the raw product gas in presence of calcium oxide. The CO and concentrations in the product gas were lower while using the sorbent. The calcium oxide played the dual role of sorbent and catalyst. [Copyright &y& Elsevier]

This paper presents experimental study on catalytic autothermal reforming (ATR) of natural gas (NG) for hydrogen () production over sulfide nickel catalyst supported on gamma alumina. The experiments are conducted on a cylindrical reactor of 30mm in diameter and 200mm in length with “simulated” NG of different composition under thermal-neutral conditions and fed with different molar air to fuel ratio () and molar water to fuel ratio . The results showed that reforming performance is significantly dependent on , and concentration of hydrocarbons in inlet fuel. Fuels containing higher hydrocarbons concentration have optimum performance in terms of more at higher and but lower conversion efficiency. Good performance for ATR of fuel containing 15%–20% can be achieved at and , much higher than that for optimum performance of ATR of methane (). In the inlet fuel does not have significant effect on the reversed water–gas shift reaction. Its effect on reforming performance is mainly due to the dilution of inlet fuel and products. [Copyright &y& Elsevier]

Abstract: This paper describes the synthesis and characterization of ceramic microreactors composed of inverted beaded silicon carbide (SiC) monoliths with interconnected 0.75-, 2.2-, or 7.2-μm pores as catalyst supports, integrated within high-density alumina reactor housings obtained via an optimized gel-casting procedure. Structural characterization revealed that these tailored macroporous SiC porous monoliths are stable at temperatures up to at least 1200 °C, and have surface areas and porosities as high as and 74%, respectively. Further characterization of the ceramic microreactors using the decomposition of ammonia with Ru as the catalyst at temperatures between 450 and 1000 °C showed that as much as 54 sccm of hydrogen, or H2 per cm3 of monolith volume, could be obtained from a 36-sccm entering stream of NH3 at >99.9% conversion at temperatures above 700 °C. Moreover, using SiC as a catalyst support appears to increase the catalytic activity of the Ru catalyst, as evidenced by high turnover frequencies. [Copyright &y& Elsevier]

Nickel on alumina support offers opportunity for gasification of biomass for hydrogen production. In a recent contribution from our research team, (González Castañeda, D. G., et al. 2019) showed that cerium or lanthanum co-impregnation at 2 wt% with nickel may have a favorable effect for biomass catalytic gasification. However, and given an observed influence of lanthanum on the formation of small Ni crystallite sizes, five Ni/γ-Al2O3 based fluidizable La promoted catalysts were studied. Nickel-alumina catalysts promotion was effected varying La in the 0.5 and 1.0 wt% range. Once impregnation precursors loaded, they were reduced at 480 °C via an activation step. Catalysts were characterized using BET, XRD, AA, TPR, TPD, H2-chemisorption, TEM-EDX and FTIR. Catalyst performance was established in a fluidized CREC Riser Simulator, using: a) glucose as surrogate biomass, b) 600 °C, c) steam/biomass (S/B) ratio of 1, d) catalyst /biomass (C/B) ratio of 3.2 and e) 20 s reaction time. Data obtained was analyzed using an ANOVA statistical data analysis package with the 5 wt% Ni and 0.5–1 wt% La and Ce on γ-Al2O3 catalysts, prepared using a pH of 1 of impregnating solution were the best yielding 0.53–0.56 hydrogen molar fractions. These catalysts also gave a 39% reduced coke, and this while compared with the coke formed on the 2% Ce – 5 wt%Ni/γ-Al2O3 (González Castañeda, D. G., et al. 2019). This promising performance was assigned to the dominant NH3-TPD medium acidity, the high catalyst specific surface (∼140 m2/g), and the good 9% metal dispersion with 9–10 nm nickel crystallites. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrogen production from a sulfide/sulfite solution is one of the photocatalytic processes that have been of interest recently for hydrogen production. Different types of semiconductor photocatalysts have been prepared and tested for this purpose. In this paper, photocatalysts CdS/ZnS that were prepared by a different coprecipitation technique was studied with and without n-Si in sulphide/sulphite solution irradiated with direct sunlight at laboratory level. From the study of variation in composition of CdS/ZnS, 2:1(by weight) composition was found to be very efficient for hydrogen production. The rate of hydrogen liberation was achieved by addition of n-Si. The maximum hydrogen has been produced with the photocatalyst CdS/ZnS/n-Si (2/1/1.4–1.6%). The recorded maximum hydrogen evolution rate was 35.5 ml h−1 g−1 in 250 ml 0.24 M Na2S and 0.35 M Na2SO3 solution. [Copyright &y& Elsevier]

Fuel cell electric vehicles have recently experienced rising demand. The geographic coverage of hydrogen stations, however, is limited. This study proposes an on-site hydrogen production system that converts heavy naphtha to high-purity hydrogen for remote areas without convenient access to hydrogen. It includes a pressurized steam reformer (SR) to produce H 2 -rich gas and a catalytic membrane reactor (MR) to promote H 2 -producing reactions and permeate hydrogen. By utilizing the liquid-fuel infrastructure, this compact system can produce hydrogen effectively and make it more accessible. Our paper describes how we maximize the system's hydrogen output by investigating how the operating conditions affect each component. Various tests are performed to select the system's water-gas-shift catalyst (Fe–Cr) and determine the optimal temperatures of the SR (800 °C) and the MR (400 °C). The MR shows enhanced catalytic performance from hydrogen permeation or 1.63 times higher hydrogen output at 25 bar(g) than a reactor that contains only catalyst (no membrane). At this pressure, the MR has a maximum hydrogen output at different SR reformate compositions. The maximization is possible by incorporating Le Chatelier's principle and minimizing methanation. This work is important because it proposes a comprehensive method to maximize on-site hydrogen output and ensure the MR's stable operation. • An MR system using heavy naphtha for on-site H 2 stations was proposed. • The membrane and SR/WGS catalysts were investigated for their system performance. • The MR's permeance and methanation competed and caused a new performance peak. • We solved the issues of methanation and membrane damage observed in past studies. [ABSTRACT FROM AUTHOR]

The use of highly-active and robust catalysts is crucial for producing green hydrogen by water electrolysis as we strive to achieve global carbon neutrality. Noble metals like platinum are currently used catalysts in industry for the hydrogen evolution, but suffer from scarcity, high price and unsatisfied performance and stability at large current density, restrict their large-scale implementations. Here we report the synthesis of a type of monolith catalyst consisting of a metal disulfide (e.g., tantalum sulfides) vertically bonded to a conductive substrate of the same metal tantalum by strong covalent bonds. These features give the monolith catalyst a mechanically-robust and electrically near-zero-resistance interface, leading to an excellent hydrogen evolution performance including rapid charge transfer and excellent durability, together with a low overpotential of 398 mV to achieve a current density of 2,000 mA cm−2 as required by industry. The monolith catalyst has a negligible performance decay after 200 h operation at large current densities. In light of its robust and metallic interface and the various choices of metals giving the same structure, such monolith materials would have broad uses besides catalysis. Water electrolysis is a promising hydrogen production technique but is restricted from large-scale application due to poor performance and high cost. Here, the authors report a mechanically stable monolith electrocatalyst that achieves superior hydrogen evolution at large current densities. [ABSTRACT FROM AUTHOR]

NiCl2·6H2O ([Ni(H2O)6]2Cl2) per se does not show electrocatalytic hydrogen evolution reaction activity (HER) in an acidic aqueous medium as well as in neutral water. Interestingly, when [Ni(H2O)6]2+ is present in a polyoxovanadate matrix, for example, in the compound K2[Ni(H2O)6]2[V10O28]·4H2O (1), it exhibits homogeneous electrocatalytic HER activity in an acidic aqueous solution with a turn over frequency of 2.1 s−1 and an effective low overpotential of 127 mV at pH 2.3. Compound 1 is the first nickel-containing polyoxometalate catalyst for hydrogen production via homogeneous electrocatalytic proton reduction without its decomposition under electrochemical conditions of HER. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: In this work, we screened three Grubbs catalysts and two Hoveyda‐Grubbs catalysts for the production of H2 by dehydrogenation of formic acid (FA). The best results were achieved with the use of a first‐generation Hoveyda‐Grubbs catalyst. With a catalyst loading of mere 0.5 μmol, a maximum TON of 36356 was obtained within 3 h. Two key intermediates were identified by using 1H NMR and high‐resolution electrospray ionization mass spectroscopy (HRESI‐MS), based on which a mechanism possibly responsible for the observed catalysis was proposed. [ABSTRACT FROM AUTHOR]

Summary: M‐Al (M = Mg, Ni, Co, Zn) hydrotalcite was synthesized on the surface of the γ‐Al2O3 carrier, and hydrotalcite was calcined to corresponding carrier. Then, A series of Cu‐Ce/M‐Al catalysts were prepared by the sequential dip method. The catalysts were characterized by the means of XRD, BET, H2‐TPR, and XPS, which investigated the effects of different divalent metals M on the structure, properties, and catalytic performance of hydrotalcite derived catalysts for hydrogen production from methanol steam reforming. The main reasons for different effects on the performance of catalysts lie in the difference of the dispersion, reduction temperature, and the content of oxygen vacancies on the surface. Among them, Ce‐Cu/Zn‐Al catalyst had the best performance. When the reaction temperature was 250°C, the molar ratio of water to methanol was 1.2, and the space velocity of methanol gas was 800 hours−1, the methanol conversion reached 100%, and the H2 production rate was 779.7 STP cm3 kg−1 s−1. [ABSTRACT FROM AUTHOR]

We have studied the effect of the reducing gas (H2, CO and CH4) on the hydrogen production by thermo-oxidation of water over the 1%Rh/Ce0.6Zr0.4O2 catalyst prepared by impregnation. The catalyst is characterized by hydrogen chemisorption (Hc), before and after catalytic decomposition of water, temperature-programmed desorption, temperature-programmed reduction, X-ray diffraction and scanning electron microscopy. The catalyst is reduced in situ at 500 °C (4 h) under H2, CO or CH4 flows and flushed with Ar gas. Then, pulses of water (1 μL/pulse) are injected at 500 °C under Ar flow (30 mL/min). The results show clearly that the reducing gas has a strong effect on the H2 production which follows the order: H2 > CH4 > > CO. H2 chemisorption measurements at room temperature highlight a strong metal–support interaction over fresh reduced catalysts which decreases after water decomposition (reduced centers + H2O → oxidized centers + H2). [ABSTRACT FROM AUTHOR]

The composite catalyst of crystalline Co(OH)2 modified rare-earth perovskite-type LaNiO3 was synthesized by physical precipitation-sol high temperature calcination method. The ratio between La/Ni and between Co(OH)2/LaNiO3 added presence obvious impact on hydrogen production performance. Under the illumination of the cut-off filter (≥ 420 nm), when the molar ratio between La/Ni is 2:1, the hydrogen production amount at 5 h reached 70.89 μmol. The hydrogen production of Co(OH)2/LaNiO3 under the optimal catalytic conditions was 4.5 times higher than of pure LaNiO3. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed good crystallinity of the sample and successful synthesis of the material. TEM and SEM were used to detect the appearance of the catalytic material. The Photoluminescence spectrum (PL), ultraviolet–visible spectroscopy (UV–Vis) and electrochemical workstations were used to characterize the catalytic performance, which is consistent with the hydrogen production results. It is indicated that the bulk Co(OH)2 acts as an electron collector in the catalytic process, which significantly increases the transfer rate of photoelectrons, enhance the hydrogen production performance. [ABSTRACT FROM AUTHOR]