Route For Hydrogen Production Research Articles

Kinetic features of ethanol steam reforming and decomposition using a biochar-supported Ni catalyst

The catalytic steam reforming of bio-ethanol will provide a sustainable route for renewable hydrogen production in a future hydrogen economy. Ni catalysts will be an economically attractive alternative to noble metals. Biochar is a promising reforming catalyst or catalyst support, having shown already good activity for tar reforming. The structure of biochar, its inherent alkali and alkaline earth metallic species and the content of O-containing functional groups are factors affecting its catalytic performance. A kinetic study of ethanol steam reforming and decomposition over a biochar-supported Ni catalyst is presented in this study in order to elucidate the role of biochar in the reaction mechanism. The effects of temperature, space velocity and reactant partial pressure were investigated over a range of conditions. The chemical structural features of used biochar samples were characterized with Raman spectroscopy. Biochar itself was found to be catalytically active and participating in ethanol reforming and decomposition. It was established that the reactions on Ni and biochar active sites were not independent. Analysis of kinetic compensation effects showed commonality on biochar and suggested that the rate-limiting step occurs in the dehydrogenation pathway on the biochar surface. O-containing functional groups in biochar were observed to reduce with reforming/decomposition time.

Catalytic and Photothermo-catalytic Applications of TiO2-CoOx Composites

Objective: The necessity to have green and sustainable industrial processes has promoted new technologies for air and water purification together with the research of new energy sources. In this contest, the TiO2-based photocatalysis can be considered a promising route for both environmental applications aIn this work, we have investigated the photocatalytic performance of TiO2-CoOx composites on both photooxidation and photoreduction reactions. Specifically, we have compared the performance of the composites in the thermo-catalytic, photo-catalytic and photothermal-catalytic oxidation of ethanol chosen as model volatile organic compound (VOC) and in the photocatalytic hydrogen production by simulated solar light from aqueous solution of ethanol.nd hydrogen production through water splitting. Background: The necessity to have green and sustainable industrial processes has promoted new technologies for air and water purification together with the research of new energy sources. In this contest, the TiO2-based photocatalysis can be considered a promising route for both environmental applications and hydrogen production through water splitting. Methods: The samples were prepared with a simple impregnation method, and were characterized by Scanning Electron (SEM) and Transmission Electron (TEM) microscopies, X-ray powder diffraction (XRD), N2 adsorption-desorption measurements, Temperature Programmed Reduction in hydrogen (H2- TPR) and X-ray Photoelectron (XPS), Raman, UV-Vis Diffuse Reflectance (UV-Vis DRS) and Photoluminescence (PL) spectroscopies. The catalytic and photocatalytic activity were carried out on pyrex reactors irradiated with a solar lamp and analyzing the reactions products through gas chromatography. Results: The presence and the amount of cobalt oxide were found crucial in determining the performance of the TiO2-based composites for both the catalytic and photocatalytic processes. In particular, the addition of 1 weight percent of CoOx led to the best performance in the photocatalytic processes, whereas a higher amount was beneficial in the thermo-catalytic tests. The multi-catalytic approach based on the synergistic effect of photocatalysis and thermocatalysis in the presence of the TiO2-1%CoOx sample allowed the temperature necessary to obtain 50% ethanol conversion and 50% yield in CO2 to be reduced by 40°C and 50°C, respectively. The same sample was also the best catalyst for photocatalytic solar H2 production. Conclusion: The presence of small amounts of cobalt oxide leads to an efficient composite with TiO2 facilitating the space charge separation and increasing the lifetime of the generated photoholes and electrons. The wide versatility of TiO2-CoOx catalysts both for photooxidation and photoreduction reactions motivates to further exploit the use of these systems in real solar-driven photocatalysis.

Dynamics of bacterial communities and substrate conversion during olive-mill waste dark fermentation: Prediction of the metabolic routes for hydrogen production

The aim of this work was to study the biological catalysts and possible substrate conversion routes in mesophilic dark fermentation reactors aimed at producing H2 from olive mill wastewater. Bacillus and Clostridium were the most abundant phylotypes during the rapid stage of H2 production. Chemical analyses combined with predictive functional profiling of the bacterial communities indicated that the lactate fermentation was the main H2-producing route. In fact, during the fermentation process, lactate and acetate were consumed, while H2 and butyrate were being produced. The fermentation process was rich in genes that encode enzymes for lactate generation from pyruvate. Lactate conversion to butyrate through the generation of pyruvate produced H2 through the recycling of electron carriers via the pyruvate ferredoxin oxydoreductase pathway.Overall, these findings showed the synergy among lactate-, acetate- and H2-producing bacteria, which complex interactions determine the H2 production routes in the bioreactors.

Fabrication of Magnetic Superstructure NiFe2O4@MOF-74 and Its Derivative for Electrocatalytic Hydrogen Evolution with AC Magnetic Field.

As an ideal hydrogen production route, electrolyzed water still faces the challenges of high cost of noble-metal electrocatalysts and low performance of non-noble-metal catalysts in scalable applications. Recently, introduction of external fields (such as magnetic fields, light fields, etc.) to improve the electrocatalytic water splitting performance of non-noble-metal catalysts has attracted great attention due to their simplicity. Here, a simple method for preparing magnetic superstructure (NiFe2O4@MOF-74) is described, and the hydrogen evolution reaction (HER) behavior of its carbonized derivative, a ferromagnetic superstructure, is revealed in a wide range of applied voltage under an AC magnetic field. The overpotential (@10 mA cm-2) required for the HER of the obtained ferromagnetic superstructure in 1 M KOH was reduced by 31 mV (7.7%) when a much small AC magnetic field (only 2.3 mT) is applied. Surprisingly, the promotion effect of the AC magnetic field is not monotonically increasing with the increase of the applied voltage or the strength of AC magnetic field, but increasing first, then weakening. This unusual behavior is believed to be mainly caused by the enhanced induced electromotive force and the additional energy by the applied AC magnetic field. This discovery provides a new idea for adjusting the performance of electrocatalytic reactions.

Propane steam reforming on mesoporous NiO–MgO–SiO2 catalysts for syngas production: Effect of the MgO/SiO2 molar ratio

In this research, a series of NiO-xMgO-SiO2 catalysts with various MgO/SiO2 molar ratios were prepared via precipitation method followed by a hydrothermal treatment in the presence of PVP as surfactant. The synergic effect between MgO and SiO2 leading to the various characteristic and catalytic performance during propane steam reforming was investigated in detail. The results showed that 15 wt% NiO-0.5MgO–SiO2 catalyst possessed the highest catalytic activity (68.9% conversion for C3H8 at 550 °C) with a negligible amount of carbon formation after 20 h of reaction duration. This superior catalytic performance can be attributed to the enhanced basicity strength along with strong metal-support interaction due to the formation of NiO–MgO solid solution, as confirmed by CO2-TPD and TPR analyses, respectively. In addition, the maximum hydrogen yield was obtained through the NiO–MgO sample because of higher progress in other hydrogen production routes as opposed to that of the propane steam reforming. It also can be suggested that relatively weak interaction between active sites and support was probably the main reason for unstable catalytic behavior of NiO–SiO2 sample with the lowest activity. This study confirms that the appropriate MgO/SiO2 ratio led to the sufficient metal-support interaction and delicate balance between acidic/basic sites, which was followed by the great activity, and coke resistance during PSR.

Interfacial engineering of Ni/V2O3 for hydrogen evolution reaction

Electrocatalytic water splitting offers a sustainable route for hydrogen production, enabling the clean and renewable alternative energy system of hydrogen economy. The scarcity and high-cost of platinum-group-metal (PGM) materials urge the exploration of high-performance non-PGM electrocatalysts. Herein, a unique hierarchical structure of Ni/V2O3 with extraordinary electrocatalytic performance (e.g., overpotentials as low as 22 mV at 20 mA·cm−2 and 94 mV at 100 mA·cm−2) toward hydrogen evolution reaction in alkaline electrolyte (1 M KOH) is reported. The investigation on the hierarchical Ni/V2O3 with a bimodal size-distribution also offers insight of interfacial engineering that only proper Ni/V2O3 interface can effectively improve H2O adsorption, H2O dissociation as well as H adsorption, for an efficient hydrogen production.

Functional use of CO2 for environmentally benign production of hydrogen through catalytic pyrolysis of polymeric waste

A benign route for hydrogen (H2) production is environmentally desirable. To achieve this, H2 synthesis from polymeric waste was investigated. A new route was sought to maximize H2 production with the least formation of coke during catalytic pyrolysis of fishing net waste (FNW) by using CO2 (as reaction media) and a Ni/SiO2 (as catalyst). The thermolytic characteristics of FNW were also evaluated under the CO2 condition (and N2 as reference environment) both with and without catalysts to assess the full scope of variabilities involved in catalytic pyrolysis of FNW. The use of Ni/SiO2 catalyst in each of the N2 and CO2 conditions improved the reaction kinetics in terms of syngas formation with significant production of H2 (1,543 and 770 mmol g−1cat h−1) and CO (11 and 1157 mmol g−1cat h−1), respectively. However, H2 production rate dropped when the catalyst was deactivated due to (hydro)carbon deposition onto the catalyst surface under N2 environment. Under CO2 environment, CO2 served as an oxidant during FNW thermolysis with additional CO formation and prolonged lifetime of catalyst (via suppressed deactivation). H2 production mediated by CO2 increased to ≥1,093 mmol g−1cat h−1 during five repeated cycles of FNW pyrolysis, coupling with water–gas shift reaction (WGS: CO+H2O⇌H2+CO2). This new approach to H2 production is demonstrated as a practical measure for producing H2 while extending catalyst life.

Environmental evaluation of european ammonia production considering various hydrogen supply chains

Ammonia synthesis is a topic of high interest in the industry as the market continues to expand and demand increases. The current ammonia production route is very energy and carbon-intensive, relying greatly on natural gas both as feedstock as well as for heat and power generation within the plant. In the present work, a cradle-to-gate environmental assessment of conventional and greener hydrogen production routes integrated with ammonia synthesis is carried out according to ReCIPe impact assessment method. Hydrogen production through conventional steam methane reforming coupled with gas-liquid carbon dioxide absorption by amines and chilled ammonia, electrolysis, and iron-based chemical looping are analysed and compared. Mass and energy balances from process flow modelling are used as inputs for the environmental evaluation using Life Cycle Assessment. The system boundaries considered in this work include: i) main processes: ammonia production, hydrogen production, carbon dioxide separation; ii) upstream processes: nitrogen, natural gas, ilmenite, Methyl-DiEthanol-Amine, chilled ammonia and catalysts supply chains, iii) downstream processes: carbon dioxide compression, transport and storage, degradation/disposal of solvents/oxygen carrier. The results show that natural gas-based ammonia synthesis integrated with chemical looping hydrogen production gives the highest reduction in Global Warming Potential while six out of the nine investigated impact indicators (excluding Global Warming Potential) suffer an increase between 30% and 60%. In the case of hydrogen produced from electrolysis, unless the electricity necessary for electrolysis is obtained from non-fossil sources, it results in the highest overall emissions to air, water and soil.

Sulfur-Doped CoSe2 Porous Nanosheets as Efficient Electrocatalysts for the Hydrogen Evolution Reaction.

The electrochemical hydrogen evolution reaction (HER), as a promising route for hydrogen production, demands efficient and robust noble-metal-free catalysts. Doping foreign atoms into an efficient catalyst such as CoSe2 could further enhance its activity toward the HER. Herein, we developed a solvothermal ion exchange approach to doping S into CoSe2 nanosheets (NSs). We provide a combined experimental and theoretical investigation to establish the obtained S-doped CoSe2 (S-CoSe2) nanoporous NSs as highly efficient and Earth-abundant catalysts for the HER. The optimal S-CoSe2 catalyst delivers a catalytic current density of 10 mA·cm-2 for the HER at an overpotential of only 88 mV, demonstrating that S-CoSe2 is one of the most efficient CoSe- and CoS-based catalysts for the HER. We performed density functional theory (DFT) calculations to determine the stable structural configurations of S-CoSe2, and on the basis of which, we calculated the hydrogen adsorption Gibbs free energy (ΔGH) on CoSe2, CoS2, and the S-CoSe2 and the barrier energies of the rate-determining step of the HER on S-CoSe2. DFT calculations reveal that S-doping not only decreases the absolute value of ΔGH (move toward zero) but also significantly lowers the kinetic barrier energy of the rate-determining step of the HER on S-CoSe2, leading to a greatly improved HER performance.

Microbial electrolysis cells for hydrogen production

Microbial electrolysis cells (MECs) present an attractive route for energy-saving hydrogen (H2) production along with treatment of various wastewaters, which can convert organic matter into H2 with the assistance of microbial electrocatalysis. However, the development of such renewable technologies for H2 production still faces considerable challenges regarding how to enhance the H2 production rate and to lower the energy and the system cost. In this review, we will focus on the recent research progress of MEC for H2 production. First, we present a brief introduction of MEC technology and the operating mechanism for H2 production. Then, the electrode materials including some typical electrocatalysts for hydrogen production are summarized and discussed. We also highlight how various substrates used in MEC affect the associated performance of hydrogen generation. Finally we presents several key scientific challenges and our perspectives on how to enhance the electrochemical performance.

Activating the Pd-Based catalysts via tailoring reaction interface towards formic acid dehydrogenation

Formic acid dehydrogenation (FAD) offers an ideal route for hydrogen production, where searching for efficient and selective catalysts is imperative. However, the current state-of-the-art Pd-based metallic catalysts severely suffer from low catalytic efficiency and self-poisoning, owning to the FA dehydration side reaction. In this work, we design PANI-Pd/C composite catalysts via interfacial microenvironment regulation technique. The as-prepared 0.01-PANI-Pd/C catalyst exhibits high turnover frequency (TOF, 5654 h−1) and excellent resistance to CO poisoning. The merit of polyaniline can be ascribed to: a) construction of abundant Pd–PdO interfaces; b) capturing H+ and accelerating the formation of the reactive species.

NiFeMo Alloy Inverse-Opals on Ni Foam As Outstanding Catalysts for Alkaline Electrolytic Water Splitting

Hydrogen, a clean energy carrier with a high gravimetric energy density, is currently most economically produced with steam reforming of natural gases, in which fossil fuels are used as the raw material and CO2 is generated as a side product, both not environmentally sustainable. Renewable energy driven electrocatalytic water splitting is considered the most promising route for future hydrogen production. Its production cost, dominated by the electric energy consumption, however places it in a disadvantageous position, and highly efficient, cost-effective, and durable electrocatalysts, aiming to reduce the necessary working potential for cost competiveness, are critically important for the prevailing of the technology. The present work developed, based on the essential concept of improving quantity and quality of active sites of the catalyst, NiFeMo alloy inverse-opals on nickel foam as an extraordinary catalyst for alkaline electrolytic water splitting, achieving ultralow overpotentials of 33 and 249 mV for the hydrogen evolution reaction (HER) and 198 and 293 mV for the oxygen evolution reaction (OER) at current densities of 10 and 500 mA cm-2, respectively. Ultralow cell voltages of only 1.47 and 1.75 V are enough to deliver current densities of 10 and 500 mA cm-2, respectively, for overall water splitting, outperforming the benchmark couple, Pt/C and IrO2, and state-of-the-art electrolytic water splitting cells. The stability of the product is also outstanding, remaining stable after operations at an ultrahigh current density of 500 mA cm-2 for 50 hours. The success of the product catalyst is attributed to the much increased active site number with the construction of inverse-opals on nickel foam and the much enhanced intrinsic activities of the active sites through synergistic effects between the three constituent elements.

An experimental and modeling study aiming to enhance the performance of OSR of a methane fuel processor via Box-Behnken design

OSR is the energy efficient hydrogen production route used in small scale fuel processors. The performance of the methane OSR catalyst is crucial for the overall performance of FPs. Current work proves the activity and hydrogen selectivity of OSR catalyst can exceed thermodynamic limits if the contact time is defined properly. It furtherly shows the intricate nature of OSR, comprising synchronous series and parallel reactions, can be modeled parsimoniously unveiling the effect of parameters. Results of total 27 experiments according to a Box-Behnken (BB) design revealed higher CH4 conversion values were experimentally obtained for higher temperature, higher S/C feed ratio and lower C/O2 feed ratio with certain exception(s) for S/C feed ratio; however, mostly lower CH4 conversion values were observed for higher catalyst weight, i.e. higher contact time. Contrary to the conventional practice of including up to quadratic terms in the BB models, statistical analysis shows the necessity of including 3rd order two-way interaction terms in the models. The most statically significant 3rd order interaction terms were those between W and S/C, which are required to explain the unexpected partial effects of W and S/C on response variables.

Biorenewable hydrogen production through biomass gasification: A review and future prospects

Hydrogen is recognized as one of the cleanest energy carriers, which can be produced from renewable biomass as a promising feedstock to achieve sustainable bioeconomy. Thermochemical technologies (e.g., gasification and pyrolysis) are the main routes for hydrogen production from biomass. Although biomass gasification, including steam gasification and supercritical water gasification, shows a high potential in field-scale applications, the selectivity and efficiency of hydrogen production need improvement to secure cost-effective industrial applications with high atom economy. This article reviews the two main-stream biomass-to-hydrogen technologies and discusses the significance of operating conditions and considerations in the catalytic system design. Challenges and prospects of hydrogen production via biomass gasification are explored to advise on the critical information gaps that require future investigations.

Hydrogen production via catalytic propane partial oxidation over Ce1-xMxNiO3-λ (M=Al, Ti and Ca) towards solid oxide fuel cell (SOFC) applications

Indirect hydrogen production routes presented extensive compatibilities for distributed solid oxide fuel cell systems. Catalyst activity directly determines hydrogen production and profoundly affects the power generation. In this work, Ce1-xMxNiO3-λ (M = Al, Ti and Ca) were synthesized for hydrogen production from propane partial oxidation (POx). From the results, it indicated that the choice of catalyst compositions could directly affect the microstructure during the preparation process. Also, different Ce1-xMxNiO3-λ catalysts displayed distinctive carbon tolerance performances due to the different active particle sizes and surface properties of the catalysts. In general, the synthesized Ce1-xMxNiO3-λ catalysts showed higher hydrogen production than a commercial nickel cerium catalyst. From the observation of a SOFC test system powered by injecting the generated H2 from catalytic propane POx reaction, the obtained power density of CNO–Al displayed an increase of 22.6% compared to the commercial nickel cerium catalyst. It was quite impressive that the equivalent hydrogen (160 ml/min) produced over CNO–Al and the obtained power density (482.6 mW/cm2) of SOFCs were competitive while CNO–Ca presented an excellent stability with a better carbon tolerance performance for the long-term tests. The achievements of this work might offer a novel point of view for developing low-cost catalyst towards indirect hydrogen production for SOFC.

Silicon and Phosphorus Co-doped Bipyridine-Linked Covalent Triazine Framework as a Promising Metal-Free Catalyst for Hydrogen Evolution Reaction: A Theoretical Investigation.

Electrocatalytic water spliting is the most attractive route for hydrogen production, but the development of nonprecious, stable, and high-performance catalysts for hydrogen evolution reaction (HER) to replace the scarce platinum group metal-based electrocatalysts is still a challenging task for the scientific community. In this work, within the framework of density functional theory computations, we have predicted that a silicon and phosphorus co-doped bipyridine-linked covalent triazine framework, followed by substitution of bipyridine hydrogens at the P-site with fluorine atoms, may be a potential catalyst for HER. Our predicted model system (SiPF-Bpy-CTF) exhibits a very low band gap (7 meV), which may exhibit facile charge transfer kinetics during HER. Using the Gibbs free energy for the adsorption of atomic hydrogen ([Formula: see text]) as the key descriptor, we have found that our proposed model system (SiPF-Bpy-CTF) exhibits superior HER catalytic activity, with its [Formula: see text] being close to the ideal value (0 eV).

Net energy and carbon footprint analysis of solar hydrogen production from the high-temperature electrolysis process

This paper assesses the viability of the solar-based high-temperature steam electrolysis (HTSE) process by estimating the cumulative energy demand (CED) and carbon emission footprint (CEF) of hydrogen. In the analysis, photovoltaic (PV) and concentrated solar power (CSP) plants are considered as the source of electricity. The trend of variation in CED and CEF with the changing temperature and current density of the solid oxide electrolyzer is obtained. The requirements for the feasibility of the HTSE process is established by comparing the results with the solar-based alkaline electrolysis process. Monte Carlo simulation is done to capture the effects of data and performance uncertainties. The carbon footprint of the solar-based high-temperature and alkaline electrolysis processes are also compared with the renewable, nuclear and hydrocarbon-based routes for hydrogen production. The CED of the PV and CSP based HTSE processes are 15.1–28 MJ/kg of hydrogen and 18.8–30.1 MJ/kg, respectively. This implies a net energy gain of 90–104 MJ/kg of hydrogen. The carbon footprint of the PV and CSP driven processes are 1.03–1.87 kg CO2/kg of hydrogen and 1.05–1.67 kg/kg, respectively. The carbon footprint of the steam methane reforming (SMR) process, solar-based alkaline electrolysis, and thermochemical cycles are 10.6 kg/kg, 2–2.3 kg/kg and 4.3–4.5 kg/kg respectively. Thus, the solar-HTSE process is a sustainable alternative not only to the SMR route but also to other solar technologies like alkaline electrolysis and thermochemical cycles. It is recommended that the solar-HTSE route should be further explored by demonstrating the technology on a pilot scale.

Colloidal Co single-atom catalyst: a facile synthesis strategy and high catalytic activity for hydrogen generation

A facile route for on-demand hydrogen production via simply controlling the mixing process of a KBH4 solution and an aqueous solution of ISOBAM-104 stabilized Co2+ ions.

Hydrogen from solar energy, a clean energy carrier from a sustainable source of energy

Solar energy is going to play a crucial role in the future energy scenario of the world that conducts interests to solar-to-hydrogen as a means of achieving a clean energy carrier. Hydrogen is a sustainable energy carrier, capable of substituting fossil fuels and decreasing carbon dioxide (CO2) emission to save the world from global warming. Hydrogen production from ubiquitous sustainable solar energy and an abundantly available water is an environmentally friendly solution for globally increasing energy demands and ensures long-term energy security. Among various solar hydrogen production routes, this study concentrates on solar thermolysis, solar thermal hydrogen via electrolysis, thermochemical water splitting, fossil fuels decarbonization, and photovoltaic-based hydrogen production with special focus on the concentrated photovoltaic (CPV) system. Energy management and thermodynamic analysis of CPV-based hydrogen production as the near-term sustainable option are developed. The capability of three electrolysis systems including alkaline water electrolysis (AWE), polymer electrolyte membrane electrolysis, and solid oxide electrolysis for coupling to solar systems for H2 production is discussed. Since the cost of solar hydrogen has a very large range because of the various employed technologies, the challenges, pros and cons of the different methods, and the commercialization processes are also noticed. Among three electrolysis technologies considered for postulated solar hydrogen economy, AWE is found the most mature to integrate with the CPV system. Although substantial progresses have been made in solar hydrogen production technologies, the review indicates that these systems require further maturation to emulate the produced grid-based hydrogen.

Lignocellulose to bio-hydrogen: An overview on recent developments

Production of hydrogen from lignocellulosic biomass using biological methods is an alluring approach to generate green and clean energy. However, the challenges levied by structural and compositional aspects of lignocellulosic biomass block the way to harness their complete energy potential. The review revisits the available methods of pretreatment to augment the accessibility of carbon source required for microorganism to perform biomass to hydrogen conversion. The fermentation methods that have been employed for years for bio-hydrogen production are discussed in brief to provide the background of biological routes of hydrogen production. The review further highlights the latest research trends and upgrades in technologies including the identified novel microbial strains, reactor configurations, integrated schemes of fermentations, nanocatalysts addition and the genetic engineering tactics to enhance the competence of hydrogen producing bacteria.