Low-emission hydrogen production via the thermo-catalytic decomposition of methane for the decarbonisation of iron ore mines in Western Australia

The Pilbara, located in Western Australia is one of the largest iron ore-mining regions in the world and will need to achieve significant emission reductions in the short term to conserve the limited carbon budget and abide by the Paris Agreement targets. Green hydrogen has been communicated as the desired solution, however, the high production cost limits the deployment of these systems. The thermo-catalytic methane decomposition (TCMD) process is an alternative solution, which could be implemented as a bridge technology to produce low-emission hydrogen at a potentially lower cost. This is especially attractive for iron ore mines due to the utilisation of iron ore as a process catalyst, which reduces the catalyst turnover costs and can increase the grade of spent iron ore catalyst. In this study, a preliminary techno-economic assessment was carried out in comparison with green hydrogen to determine the feasibility of the TCMD process for the decarbonisation of iron ore mine sites in the Pilbara. The results show that the TCMD process had a CO₂ abatement cost between 25 and 40% less than green hydrogen, however, the magnitude of these costs was lowest for mining operations >60 Mt/yr at approximately $150 and $200 USD/t CO₂ respectively. Since green hydrogen is expected to have significant cost reductions in the future, integrating renewables already into the mine could reduce emissions in the short term, which could then be extended for green hydrogen production once it becomes viable. The TCMD process, therefore, only has a narrow window of opportunity, although considering the uncertainty of the process and that green hydrogen is a proven technology with greater emission-reduction potential, green hydrogen may be the most suitable solution despite the model results presented in this work.     

Encapsulation of Pt nanocatalyst with N-containing carbon layer for improving catalytic activity and stability in the hydrogen evolution reaction

As hydrogen emerges as a next-generation clean energy source, the production of hydrogen is generating much research interest. Water electrolysis, one of the promising methods of hydrogen production, has the advantage of no resource depletion or carbon dioxide emissions. In this study, a Pt@C core–shell catalyst in which an N-containing carbon layer covers individual Pt nanoparticles was applied to the hydrogen evolution reaction (the cathodic reaction of water electrolysis), and the effect of the carbon shell on the activity and stability of the catalyst was investigated. The catalyst was synthesized by simple annealing of Pt-aniline complexes at 600 °C in a N₂ atmosphere. The thermal decomposition of aniline during annealing resulted in N-containing carbon shells. The carbon shell had a positive effect on both the activity and stability of the catalyst in the hydrogen evolution reaction. Graphitic N and pyridinic N on the carbon shell, along with Pt, served as active sites for the hydrogen evolution reaction, increasing the catalytic activity. The carbon shell also effectively protected the Pt core from dissolution and agglomeration while allowing the transport of the reactant protons through the shell, improving stability with minimal loss of catalytic activity.     

Investigation of the benefits of diabatic microreactors for process intensification of the water-gas shift reaction within the steam reforming process

Currently, the steam reforming process is the largest industrial source of hydrogen. Improving its efficiency can help to reduce associated carbon emissions and hydrogen production costs. Intensifying the water-gas shift reaction using microreactors with integrated cooling is one way of achieving this. In this study, a 2-D computational model of one of these microreactors is developed, validated with experimental data, and then used to demonstrate how microreactors can enhance the conversion of the water-gas shift reaction beyond what can be achieved using conventional packed bed reactors. These results are then generalized into a full system model of the steam reforming process to demonstrate how microreactors can reduce hydrogen production costs. The results suggest that microreactors can significantly reduce the required reactor volume and catalyst loading for the water-gas shift reaction and can similarly reduce the hydrogen production costs associated with the steam reforming process.     

A review of hydrotalcite based catalysts for hydrogen production systems

Hydrotalcite is a double layered lamellar clay and is used as a catalyst precursor due to its structural properties. Hydrotalcite derived catalysts for hydrogen production through different processes have been reviewed. Recent developments of catalysts for hydrogen production are discussed accordingly. A brief introduction to structure and different synthesis routes of hydrotalcite based catalysts is also included. Article is focused on hydrotalcite derived catalysts consisting of different metals like Fe, Ni, Cu, Pt etc. and their performances in hydrogen production at different conditions. Use of such catalysts in hydrogen production process like steam reforming, sorption enhanced based generation, and various other applications is reviewed critically. Pros and cons of catalysts are discussed in detail. The scope and challenges in development of the hydrogen production process have been detailed out focusing modified hydrotalcite derived catalyst and process conditions.     

Determination of critical catalyst preparation factors (cCPF) influencing hydrogen evolution

In recent years, the energy crisis has gotten worse as a result of global challenges like the pandemic and the Ukraine crisis. To solve this problem, researchers have focused on development of sustainable resources and renewable energy infrastructure for its potential as a promising and effective strategy. Hydrogen is a significant energy carrier that will fulfill global energy demand while also significantly reducing greenhouse gas (GHG) emissions in the future decades. The catalysts used in hydrogen generation have a substantial effect on hydrogen efficiency, however unknown parameters affecting catalyst activity throughout the catalyst preparation process are a major source of concern. The most essential components are to accurate determination the development conditions of the catalysts used in the hydrogen generation. The main objective is to produce hydrogen energy with high efficiency thereby reducing the currently usage of fossil fuels, which are currently used in transportation, industry, home, and commercial applications. This study's aim is to examine critical catalyst preparation factors (cCPF) that have an effect on the efficiency of the catalyst using the fuzzy DEMATEL method. In this regard, twelve cCPF were identified based on literature review and in consultation with experts and the causal relationships among critical factors were visualized with the proposed method. The results highlighted that the most critical CPF that should be tackled to improve hydrogen generation efficiency are: appropriate reduction temperature (F), and the appropriate reduction agent concentration (G), drying conditions (L), drying time (M) and calibration of instruments and equipment (N). The findings of this study can be used to researchers and decision-makers for improving the overall performance of catalysts.     

Pyrolysis–gasification of post-consumer municipal solid plastic waste for hydrogen production

Post-consumer plastic waste derived from municipal solid waste was investigated using a two-stage, catalytic steam pyrolysis–gasification process for the production of hydrogen. The three important process parameters of catalyst:plastic ratio, gasification temperature and water injection rate were investigated. Temperature-programmed oxidation (TPO) and scanning electron microscopy (SEM) methods were used to analyse the reacted catalysts. The results showed that there was little influence of catalyst:plastic ratio between the range 0.5 and 2.0 (g/g) on the mass balance and gas composition for the pyrolysis–gasification of waste plastics; this might be due to the effective catalytic activity of the Ni–Mg–Al catalyst. However, increasing the gasification temperature and the water injection rate resulted in an increase of total gas yield and hydrogen production. The coke formation on the catalyst was reduced with increasing use of catalyst; however, a maximum coke formation (9.6 wt.%) was obtained at the gasification temperature of 700 °C when the influence of gasification temperature was investigated. The maximum coke formation was obtained at the water injection rate of 4.74 g h⁻¹, and a more reactive form of coke seemed to be formed on the catalyst with an increase of the water injection rate, according to the TPO experiments.     

Exergy and energy analysis of hydrogen production by the degradation of sodium borohydride in the presence of novel Ru based catalyst

Chemically possible hydrogen storage material of the most important and widely used metal hydride compound is sodium borohydride. A current research issue is the development of systems that allow regulated hydrogen generation employing appropriate catalysts for the creation of hydrogen gas from the hydrolysis of sodium borohydride (NaBH₄). In this study, controlled hydrogen production from alkali solution of NaBH₄ was aimed. On hydrogen generation rate (HGR), the effects of NaBH₄ and alkaline solution concentrations, catalyst quantity, and temperature were examined. Considering the energy and exergy analysis, which have gained importance in the international arena in recent years, in this study, the exergy energy analysis of the environment in which the sodium borohydride solution is located was performed. The best one of the Ru-based catalysts synthesized in different atomic ratios was determined as 90:10 RuCr. The surface characterization of the obtained catalyst was carried out using scanning electron microscope (SEM-EDX) and X-ray diffractometer (XRD). In the kinetic calculations, the activation energy was calculated as 35,024 kj/mol and the reaction ordered n was found to be 0,65. By applying exergy and energy analysis to the hydrogen production step, the energy and exergy efficiency of the system were found to be 24% and 7%, respectively.     

Production of ultra-dense hydrogen H(0): A novel nuclear fuel

Condensation of hydrogen Rydberg atoms (highly electronically excited) into the lowest energy state of condensed hydrogen i.e. the ultra-dense hydrogen phase, H(0), has gained increased attention not only from the fundamental aspects but also from the applied point of view. The physical properties of ultra-dense hydrogen H(0) were recently reviewed (Physica Scripta 2019 https://doi.org/10.1088/1402-4896/ab1276), summarizing the results reported in 50 publications during the last ten years. The main application of H(0) so far is as the fuel and working medium in nuclear particle generators and nuclear fusion reactors which are under commercial development. The first fusion process showing sustained operation above break-even was published in 2015 (AIP Advances) and used ultra-dense deuterium D(0) as fuel. The first generator giving a high-intensity muon flux intended for muon-catalyzed fusion reactors was patented in 2017, using H(0) as the working medium. Here, we first focus on the different nuclear processes using hydrogen isotopes for energy generation, and then on the detailed processes of formation of H(0). The production of H(0) employs heterogeneous catalysts which are active in hydrogen transfer reactions. Iron oxide-based, alkali promoted catalysts function well, but also platinum group metals and carbon surfaces are active in this process. The clusters of highly excited Rydberg hydrogen atoms H(l) are formed upon interaction with alkali Rydberg matter. The final conversion step from ordinary hydrogen Rydberg matter H(l) to H(0) is spontaneous and does not require a solid surface. It is concluded that the exact choice of catalyst is not very important. It is also concluded that the crucial feature of the catalyst is to provide excited alkali atoms at a sufficiently high surface density and in this way enabling formation and desorption of H(0) clusters. Finally, the relation to industrial catalytic processes which use H(0) formation catalysts is described and some important consequences like the muon and neutron radiation from H(0) are discussed.     

Feasibility of preparing additive manufactured porous stainless steel felts with mathematical micro pore structure as novel catalyst support for hydrogen production via methanol steam reforming

In this paper, an additive manufacturing prepared porous stainless steel felt (AM-PSSF) is proposed as a novel catalyst support for hydrogen production via methanol steam reforming (MSR). In the method, 316 L stainless steel powder with diameter of 15–63 μm is processed by the additive manufacturing technology of selective laser melting (SLM). To accomplish the preparation, the reforming chamber where the AM-PSSF is embedded is firstly divided into an all-hexahedron mesh. Then, the triply periodic minimal surface (TPMS) unit with mathematical form, high interconnectivity and large specific surface area is mapped into the hexahedrons based on shape function, forming the fully connected three-dimensional (3D) micro pore structure of the AM-PSSF. By correlating the mathematical parameter and the porosity of the TPMS unit, and taking into account the SLM process, the porosity of the AM-PSSF is well controlled. Based on the designed 3D pore structure model, the AM-PSSF is produced using standard SLM process. The application of the AM-PSSF as catalyst support for hydrogen production through MSR indicates that: 1) both the naked and catalyst-coated AM-PSSF have the characteristics of high porosity, large specific surface area and high connectivity; 2) the MSR hydrogen production performance of the AM-PSSF is better than that of the commercial stainless steel fiber sintered felt. The feasibility of AM-PSSF as catalyst support for MSR hydrogen production may pave a better way to balance different requirements for catalyst support, thanks to the excellent controllability provided by AM on both the external shape and the internal pore structure, and to the produced rough surface morphology that benefits the catalyst adhesion strength. In addition, catalyst support with pore structures that are more accommodated with the flow field and the reaction rate of MSR reaction may be prepared in future, since the entire catalyst support structure, from macro scale to micro scale, is under control.     

Pellet size dependent steam reforming of polyethylene terephthalate waste for hydrogen production over Ni/La promoted Al2O3 catalyst

The effect of different pellet sizes of nickel (Ni) and lanthanum (La) promoted Al₂O₃ support on the catalytic performance for selective hydrogen production from polyethylene terephthalate (PET) plastic waste via steam reforming process has been investigated. The catalysts were prepared by impregnation method and were characterized using XRD, BET, TPD-CO₂, TPR, SEM, EDX, TEM and TGA. The results showed that NiLa-co-impregnated Al₂O₃ catalyst has excellent activity for the production of hydrogen. Feed conversion of 88.53% was achieved over 10% Ni/Al₂O₃ catalyst which increased to 95.83% in the case of 10% Ni-5% La/Al₂O₃ catalysts with a H₂ selectivity of 70.44%. The catalyst performance in term of gas production and feed conversion was further investigated under various operating parameters, e.g., feed flow-rate, and catalyst pellet size. It was found that at 0.4 ml/min feed flow rate, highest feed conversion and H₂ selectivity were achieved. The Ni particles, which are the noble-based active species are highly effective, thus offered good hydrogen production in the phenol-PET steam reforming process. Incorporation of La as a promoter in Ni/Al₂O₃ catalyst has significantly increased the catalyst reusability with prolonged stability. The NiLa/Al₂O₃ catalyst with larger size showed remarkable activity due to the presence of significant temperature gradients inside the pellet compared to smaller size. Additionally, the catalyst showed only slight decrease in H₂ selectivity and feed conversion even after 24 h, although production of carbon nanotubes was evidenced on its surface.     

Hydrogen production by catalytic processing of renewable methane-rich gases

Biomass-derived methane-rich gases such as landfill gas (LFG), biogas and digester gas are promising renewable resources for near-future production of hydrogen. The technical and economical feasibility of hydrogen production via catalytic reforming of LFG and other methane-rich gases is evaluated in this paper. The thermodynamic equilibrium calculations and experimental measurements of reformation of methane-rich CH₄–CO₂ mixtures over Ni-based catalyst were conducted. The problems associated with the catalyst deactivation due to carbon lay down and effects of steam and oxygen on the process sustainability were explored. Two technological approaches distinguished by the mode of heat input to the endothermic process (i.e., external vs autothermal) were modeled using AspenPlus^TM${\mathrm{AspenPlus}}^{\mathrm{TM}}$ chemical process simulator and validated experimentally. A 5 kW_th pilot unit for hydrogen production from LFG-mimicking CH₄–CO₂ mixture was fabricated and operated. A preliminary techno-economic assessment indicates that the liquid hydrogen production costs are in the range of $3.00–$7.00 per kilogram depending upon the plant capacity, the process heat input option and whether or not carbon sequestration is included in the process.     

Comparison of two different flow types on CO removal along a two-stage hydrogen permselective membrane reactor for methanol synthesis

Carbon monoxide (CO) is a gaseous pollutant with adverse effects on human health and the environment. Industrial chemical processes contribute significantly to CO accumulation in the atmosphere. One of the most important processes for controlling carbon monoxide emissions is the conversion of CO to methanol by catalytic hydrogenation. In this study, the effects of two different flow types on the rate of CO removal along a two-stage hydrogen permselective membrane reactor have been investigated. In the first configuration, fresh synthesis gas flows in the tube side of the membrane reactor co-currently with reacting material in the shell side, so that more hydrogen is provided in the first sections of the reactor. In the second configuration, fresh synthesis gas flows in the tube side of the membrane reactor counter-currently with reacting material in the shell side, so that more hydrogen is provided in the last sections of the reactor. For this membrane system, a one-dimensional dynamic plug flow model in the presence of catalyst deactivation was developed. Comparison between co-current and counter-current configurations shows that the reactor operates with higher conversion of CO and hydrogen permeation rate in the counter-current mode whereas; longer catalyst life is achieved in the co-current configuration. Enhancement of CO removal in the counter-current mode versus the co-current configuration results in an ultimate reduction in CO emissions into the atmosphere.     

Hydrogen production by thermo-catalytic decomposition of methane: Regeneration of active carbons using CO2

Thermo-catalytic decomposition of methane using carbons as catalyst is a very attractive process for free CO₂–hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO₂ as activating agent under different regeneration conditions. It has been stated that during the regeneration stage, a compromise between the regeneration of the initial properties of the catalyst and the burn-off is needed in order to keep the sustainability of the process. Three deactivation–regeneration cycles have been performed for two sets of regeneration conditions. A progressive decreasing in the burn-off, surface area and surface oxygenated groups after each decomposition/regeneration cycle is observed. It can be explained considering that the carbon removed during the regeneration steps is not the carbon deposited from methane but the remaining initial catalyst, which is less resistant to gasification. The implication is that after three cycles of decomposition/regeneration, most of the carbon sample consists of carbon formed during the process since the initial catalyst has been gasified.     

Effective utilization of by-product oxygen from electrolysis hydrogen production

To avoid fossil-fuel consumption and greenhouse-gas emissions, hydrogen should be produced by renewable energy resources. Water electrolysis using proton exchange membrane (PEM) is considered a promising hydrogen-production method, although the cost of the hydrogen from PEM would be very high compared with that from other mature technologies, such as steam methane reforming (SMR). In this study, we focus on the effective utilization of by-product oxygen from electrolysis hydrogen production and discuss the potential demand for it, as well as evaluating its contribution to improving process efficiency. Taking as an example the utilization of by-product oxygen for medical use, we compare the relative costs of hydrogen production by means of PEM electrolysis and SMR.     

Overview of hydrogen production from biogas reforming: Technological advancement

In this article, possibilities of biogas reforming techniques for hydrogen production are discussed. The consideration of biogas reforming to produce H₂ and fuel cell application from membrane technology is presented. In steam reforming process, methane requires a high temperature for reaction, but a suitable catalyst can manage a higher temperature. The ratio of H₂/CO is close to 3, which means higher H₂ yield (above 70%). The ratio of H₂/CO to nearly 2 and H₂ yield almost 67% and also reduces the soot formation for partial oxidation process. In Auto thermal reforming, higher yield of H₂ is around 74% with the ratio of H₂/CO close to 2.8. The dry reforming process leads to a molar ratio H₂/CO of nearly one and H₂ yield of approximately 50%. The ratio of H₂/CO correspondingly improves and generates H₂ yield of approximately 60% for dry oxidation reforming process. For sustainable decentralized power generation in remote and rural areas, large-scale development of H₂ energy technology is required. Biogas reforming is an auspicious process for the production of green hydrogen gas as well as for reducing overburden on natural gas. The main benefit of using biogas for H₂ production as a renewable energy source is reducing excessive burden on natural gas and greenhouse gas emissions. Nowadays, the importance of renewable H₂ production has increased due to many reasons such as depletion of fossil fuel reserves, global environmental issues, energy issues, and demand for pure H₂.     

Potassium catalytic hydrogen production in sorption enhanced gasification of biomass with steam

Sorption enhanced gasification (SEG) of biomass with steam was investigated in a fixed-bed reactor to elucidate the effects of temperature, catalyst type and loading on hydrogen production. K₂CO₃, CH₃COOK and KCl were chosen as potassium catalyst precursors to improve carbon conversion efficiency in gasification process. It was indicated that from 600 °C to 700 °C, the addition of K₂CO₃ or CH₃COOK catalyzed the gasification for hydrogen production, and hydrogen yield and carbon conversion increased with increasing catalyst loadings of K₂CO₃ or CH₃COOK. However, the hydrogen yield and carbon conversion decreased as the amount of KCl was increased due to inhibition of KCl on gasification. The maximum carbon conversion efficiency (88.0%) was obtained at 700 °C corresponding to hydrogen yield of 73.0 vol.% when K₂CO₃ of 20 wt.% K loading was used. In particular, discrepant catalytic performance was observed between K₂CO₃ and CH₃COOK at different temperatures and the corresponding mechanism was also discussed.     

Optimal design of wind-powered hydrogen refuelling station for some selected cities of South Africa

The transport sector is considered as one of the sectors producing high carbon emissions worldwide due to the use of fossil fuels. Hydrogen is a non-toxic energy carrier that could serve as a good alternative to fossil fuels. The use of hydrogen vehicles could help reduce carbon emissions thereby cutting down on greenhouse gases and environmental pollution. This could largely be achieved when hydrogen is produced from renewable energy sources and is easily accessible through a widespread network of hydrogen refuelling stations. In this study, the techno-economic assessment was performed for a wind-powered hydrogen refuelling station in seven cities of South Africa. The aim is to determine the optimum configuration of a hydrogen refuelling station powered by wind energy resources for each of the cities as well as to determine their economic viability and carbon emission reduction capability. The stations were designed to cater for 25 hydrogen vehicles every day, each with a 5 kg tank capacity. The results show that a wind-powered hydrogen refuelling station is viable in South Africa with the cost of hydrogen production ranging from 6.34 $/kg to 8.97 $/kg. These costs are competitive when compared to other costs of hydrogen production around the world. The cities located in the coastal region of South Africa are more promising for siting wind powered-hydrogen refuelling station compared to the cities located on the mainland. The hydrogen refuelling stations could reduce the CO₂ and CO emissions by 73.95 tons and 0.133 tons per annum, respectively.     

A GIS-based assessment of coal-based hydrogen infrastructure deployment in the state of Ohio

Hydrogen infrastructure costs will vary by region as geographic characteristics and feedstocks differ. This paper proposes a method for optimizing regional hydrogen infrastructure deployment by combining detailed spatial data in a geographic information system (GIS) with a technoeconomic model of hydrogen infrastructure components. The method is applied to a case study in Ohio in which coal-based hydrogen infrastructure with carbon capture and storage (CCS) is modeled for two distribution modes at several steady-state hydrogen vehicle market penetration levels. The paper identifies the optimal infrastructure design at each market penetration as well as the costs, CO₂ emissions, and energy use associated with each infrastructure pathway. The results indicate that aggregating infrastructure at the regional-scale yields lower levelized costs of hydrogen than at the city-level at a given market penetration level, and centralized production with pipeline distribution is the favored pathway even at low market penetration. Based upon the hydrogen infrastructure designs evaluated in this paper, coal-based hydrogen production with CCS can significantly reduce transportation-related CO₂ emissions at a relatively low infrastructure cost and levelized fuel cost.     

Constructing a new business model for fermentative hydrogen production from wastewater treatment

The development of hydrogen energy as a sustainable energy resource is essential for mitigating climate change. The primary challenge to the commercialization of hydrogen energy, relative to that of petrochemical fuels, is cost. Therefore, an innovative business model that converts the costs of procuring biomass into revenue via the production of hydrogen was developed. Profitable hydrogen production can typically be realized by lowering costs through continuous technological development and increasing scale. Feedstock procurement costs, however, limit the cost/benefit reduction flexibility. This study employs biowaste material as feedstock for biological fermentative hydrogen production. This model extends the hydrogen production value chain to include the income from biomass hydrogen production as well as the revenue from processing biowaste and reduced fuel source costs. This study investigates the costs involved in the commercialization of the hydrogen fermentation process, develops an innovative business model, and presents a case study to describe this model.     

Simulation and optimization of continuous catalytic reforming: Reducing energy cost and coke formation

Continuous catalytic naphtha reformers are one of the main refinery units producing hydrogen. Reliable and comprehensive modeling of such a complex and integrated refinery unit plays a pivotal role in optimization to increase the efficiency of the process. A reaction network with 26 pseudo components and 58 reactions, considering coke formation and catalyst activity, was proposed to predict the outlet compositions of reactors in more detail. The whole unit, including reaction and purification sections, was simulated to cover all products. NOMAD optimizer, with the mesh adaptive direct search algorithm, is used to minimize energy costs. Non-linear constraints were defined to guarantee the quality of the final products. The optimized decision variables reduced the energy cost by 13.5%, mainly caused by a significant decline in natural gas consumption. The simulation also indicated an increase of 4800 ton/y in reformate production, which the product is rich in aromatics. By contrast, LPG, hydrogen-rich gas, and coke production dropped by nearly 4355, 321, and 127 ton/y, respectively. The coke production decline can significantly increase the catalyst lifetime and decrease the operating cost of the catalyst regeneration unit.