Steam Methane Reforming Research Articles

Estimation-based model predictive control of an electrically-heated steam methane reforming process

The surge in demand for hydrogen (H2) across diverse sectors, including clean energy transportation and chemical synthesis, underscores the need for a thorough investigation into H2 production dynamics and the development of effective controllers for industrial applications. This paper focuses on an electrically heated steam methane reforming (SMR) process for H2 production, offering advantages such as enhanced environmental sustainability, compactness, efficiency, and controllability compared to conventional reforming methods. Electric heating of the entire system allows for adjustments in current to control reactor temperature, thereby impacting hydrogen production rates. However, accurately modeling hydrogen production dynamics presents a formidable challenge, as complex models with high precision are computationally unsuitable for real-time control integration. Considering these factors, an accurate and efficient first-principles-based lumped-parameter model is developed to provide a dependable estimation of hydrogen production in an electrically-heated steam methane reformer. This model is validated experimentally and then utilized in a model predictive controller (MPC). To obtain the necessary state estimate information for the MPC, an extended Luenberger observer (ELO) method is employed to estimate state variables from limited, infrequent and delayed measurements of gas-phase reactor outlet stream and frequent measurements of the reactor temperature. Simulation comparisons with a proportional-integral (PI) controller reveal a much faster response in achieving the desired H2 production rate under the estimation-based MPC. Additionally, the simulations demonstrate the robustness of the controller to process variability such as a decrease in catalyst activation energy, commonly encountered in the SMR process, highlighting its effectiveness in maintaining stable operation under varying process conditions.

Multi-scale reduced-order models of electrified wire reactors for carrying-out endothermic reactions

In chemical manufacturing applications with endothermic reactions, the heat of reaction is supplied by burning fossil fuels. Electrified reactors are one of the enticing alternatives to the traditional configurations where heating can be achieved via renewable power, leading to reduced or net-zero CO2 emissions. In this work, we consider flow-through wire-based electrified reactors and develop reduced order model (ROM) for this configuration. The ROM is expressed in terms of multiple concentration and temperature modes that are coupled with various local property dependent transfer coefficients. Steam methane reforming is selected as an example to demonstrate the utility of ROM and reactor configuration for such processes. We present a detailed sensitivity study with respect to space time and feed temperature. In addition, we also investigate the effect of power supply on the reactor performance and compare with the existing literature results. Finally, we provide physical interpretation of the ROM, describe some special cases, and discuss its applicability for other electrified reactor configurations.

Promising Directions in Chemical Processing of Methane from Coal Industry. Part 3. Catalytic Tests

For the processing of coal mine methane into hydrogen-containing gas, a catalytic process of methane tri-reforming (СH4 + O2 + CO2 + H2O) was proposed and its component reactions were studied – partial oxidation (СH4 + O2, POM), dry reforming (СH4 + CO2, DRM) and steam reforming (СH4 + H2O, SRM) of methane. Promoted nickel supported on aluminum oxide was used as a catalyst. Experiments were carried out by varying temperature (600–850 ºC), contact time (0.04–0.15 s), linear feed rate (40–240 cm/min) and composition of the reaction mixture (POM – СH4 : O2 : He = 1 : (0.5–0.7) : (3.3–3.4); DRM – СH4 : CO2 : He = 1 : (0.8–1.4) : (2.6–3.2); SRM – CH4 : H2O : He = 1 : (0.8–2.0) : (2.0–3.2)). Optimal reaction conditions were determined to ensure maximum efficiency of hydrogen production by reforming methane-containing mixtures of various compositions (temperature in the range of 800–850 ºC, contact time 0.15 s, linear feed rate 160 cm/min, molar ratio of CH4 : O2 = 1 : 0.5 for POM, CH4 : CO2 = 1 : 1 for DRM and CH4 : H2O = 1 : 1.1 for SRM). The degree of catalyst carbonization during the reactions was reduced (from 3 to 1.5% for POM, from 20.7 to 2.2% for DRM, and from 15.2 to 0.4% for SRM) due to an increase in the O/C molar ratio in the initial reaction mixture. Regulation of H2/CO molar ratio was achieved over a wide range (0.9–6.5). It has been shown that the hydrogen concentration in the resulting hydrogen-containing mixture is determined by the type of process and is equal to 30±5 vol.%.

Biogas reforming as a sustainable solution for hydrogen production: Comparative environmental metrics with steam-methane reforming and water electrolysis in the Portuguese context

This study delves into the dynamics of hydrogen production, with a specific focus on biogas reforming (BGSMR) for hydrogen generation. It compares the environmental impact of this solution with hydrogen production from natural gas-steam reforming (NGSMR) and commercial electrolysis in the Portuguese context. Various metrics, including carbon footprint, water depletion, energy utilization, and waste valorization are employed for a comprehensive comparison. The assessment explores the impact of operational parameters and different off-gas combustion scenarios, incorporating water recycling practices. Due to challenges in obtaining detailed data on the actual reforming process, the study relies on process simulation techniques, primarily using DWSIM. Commercially available data for water electrolysers were used for comparison. In the context of decarbonizing power systems, hydrogen from water electrolysis emerges as a competitive option only in a scenario where the power system is 100% reliant on renewable sources, particularly with respect to the carbon footprint metric. Biogas systems, characterized by near-zero carbon emissions, stand out as a favourable option from the near future to the long run. This research contributes valuable insights into the dynamics of hydrogen production, shedding light on environmentally viable alternatives across a range of power system scenarios.

Optimizing hydrogen yield in sorption-enhanced steam methane reforming: A novel framework integrating chemical reaction model, ensemble learning method, and whale optimization algorithm

High hydrogen production is essential in sorption-enhanced steam methane reforming (SE-SMR). This study presents an innovative optimization framework to optimize the H2 yield of SE-SMR through a coupled reaction model, prediction surrogate model, and whale optimization algorithm. Firstly, a computational fluid dynamics chemical reaction model of SE-SMR is constructed. A database is established to consider the H2 yield of SE-SMR with temperature, pressure, velocity, and steam to carbon ratio. Then, a surrogate model is developed on the basis of eXtreme Gradient Boosting (XGBoost) to predict the H2 yield under various operating parameters. Finally, the surrogate model is exploited to calculate the fitness function of the whale optimization algorithm to construct an optimization framework for maximizing the H2 yield. The results show that the XGBoost ensemble surrogate model can predict the H2 yield of SE-SMR within 4 s with high accuracy. The optimization framework can optimize the maximum H2 yield and the corresponding operating parameters within 1 min. The optimization results are validated by applying the model and the percentage error of only 0.79 %. Moreover, under optimal operating conditions, methane is almost completely converted to hydrogen, and the dry hydrogen mole fraction could reach 95.96 %. The presented optimization framework can guide the prediction of H2 yield and the optimization of operating parameters in SE-SMR.

Thermodynamic analysis of a CCHP system with hydrogen production process by methane reforming enhanced by solar-assisted chemical looping adsorption

Combined cooling, heating and power (CCHP) systems integrated with renewable energy can greatly alleviate the fossil energy crisis and greenhouse effect. This work proposes a novel CCHP system, which consists of a solar-assisted sorption enhanced chemical looping steam methane reforming (SE-CL-SMR) hydrogen generation subsystem, a solid oxide fuel cell-gas turbine (SOFC-GT) subsystem, a dual-effect Li-Br absorption chiller/heat pump (DAC/H) subsystem, and a domestic hot water (DHW) subsystem. The impacts of the reformer temperature, pressure, the ratios of steam to carbon, calcium oxide to carbon, and nickel oxide to calcium oxide on the system’s methane conversion rate, hydrogen yield, hydrogen purity, and CO2 capture efficiency are also explored. While ensuring the hydrogen production effect and considering the lowest energy consumption, the optimal reforming temperature, reforming pressure, ratios of S/C, CaO/CH4 and NiO/CaO of the CCHP system are 560 °C, 1 atm, 3, 1 and 0.5, respectively. The system’s energy and exergy analysis is performed under the optimized operating condition. In comparison with the data of reference, the findings demonstrate that the system’s overall power generation efficiency is 53.23 %, the total energy utilization rate is 74.32 %, and the exergy efficiency is 52.87 %.

Phase transition Ni-Co-Ca-O bifunctional catalysts for high and stable hydrogen production from sorption enhanced steam methane reforming

Sorption enhanced steam methane reforming (SESMR) is an effective method to improve the efficiency of hydrogen production from methane reforming while fixing CO2 to reduce carbon emissions. However, the deactivation of adsorbents during high temperature recycling limits the utilization of SESMR. In this paper, by combining the phase transition process of Ca-Co-O species and Ni-Co alloy, we prepared a series of Ni-Co-Ca-O bifunctional catalysts for SESMR hydrogen production. The 1Ni4.5Co4.5CaO catalyst exhibited high catalytic activity in the SESMR reaction with hydrogen concentration exceeding 99.6 % and complete methane conversion. The catalyst also showed high stability in 50 cycle experiments with no significant reduction in hydrogen production and CO2 uptake performance. The Ni-Co-Ca-O bifunctional catalysts consisted of NiO and Co-Ca-O species, by analyzing the fresh and reacted catalysts, the mechanism of the catalyst with high catalytic activity and stability was revealed. Firstly, the catalyst formed Ni-Co alloy and CaO adsorbent by a reduction reaction, and then the SESMR hydrogen production reaction was carried out. After the complete conversion of CaO to CaCO3, the catalyst was re-formed into NiO and Co-Ca-O species by introducing O2 in the regeneration reaction to carry out a new cycle of reduction → hydrogen production. The synergistic interaction between the Ni-Co alloy enhanced the methane reforming and water gas shift reaction, leading to an increase in hydrogen production and methane conversion. The phase transition of Co from Co-Ca-O species to Ni-Co alloy and back to Co-Ca-O species inhibited the sintering of CaO, which significantly enhanced the cyclic stability of the catalyst. The results of this study are expected to provide a new pathway for the design of SESMR bifunctional catalysts.

Enhanced co-production of high-quality syngas and highly-concentrated hydrogen via chemical looping steam methane reforming over Ni-substituted La0.6Ce0.4MnO3 oxygen carriers

Chemical looping steam methane reforming (CLSMR) is increasingly attracting more and more attention as a promising technology for co-production of syngas and hydrogen. However, low reactivity, poor selectivity and weak resistance to carbon deposition of oxygen carriers (OCs) probably discourage further commercial application of CLSMR. With this background, a novel strategy of incorporating Ce and Ni into LaMnO3 is advised to promote lattice oxygen migration rate and improve syngas selectivity. The redox activity and cycle stability of La0.6Ce0.4Mn1−xNixO3 for CLSMR are explored in a fixed-bed reactor coupling with various characterization methods. The characterization results show that La0.6Ce0.4Mn1−xNixO3 OCs still maintain the standard perovskite structures and well-ordered skeleton. The introduction of Ce3+ induces large amounts of oxygen vacancies on the surface of OCs and improve the syngas selectivity of methane reforming, leading to higher oxygen mobility and lower carbon deposition. Meanwhile, the experimental results also confirm that the doping of Ni into La0.6Ce0.4MnO3 can greatly improve the oxygen-donation ability and effectively provide more active sites for reaction with methane. While excessive Ni in perovskite will enhance the methane dissociation, which is the main reason of carbon deposits. The proper amount of Ni doping can well match the methane activation rate to migration rate of bulk lattice oxygen that is feasible to realize the balance between productivity and efficiency. In addition, the reduced metal elements along with great amounts of oxygen vacancies together contribute to more active sites for the following steam splitting which avails to produce high-purity H2. La0.6Ce0.4Mn0.7Ni0.3O3 oxygen carrier eventually achieve syngas yield of 2.8 mmol/g H2 and 1.4 mmol/g CO that is closed to the ideal value without obvious carbon deposition, and pure H2 yield of 3.8 mmol/g, exhibiting the best redox performance and good regenerability. Meanwhile, La0.6Ce0.4Mn0.7Ni0.3O3 can still maintain high redox activity and basic perovskite structure after 15 cyclic redox tests, illustrating a desirable stability and reliability. In summary, this study offers a valuable and effective strategy to tackle with the bottleneck of CLSMR, paving the way of doping transition metal as a pathway of modulating reaction performance and stability of OCs in chemical looping processes.

Technical and economic performance assessment of blue hydrogen production using new configuration through modelling and simulation

Steam methane reforming (SMR) is the dominant process for hydrogen production, which produce large amount of carbon dioxide (CO2) as a by-product. To address concerns about carbon emissions, there is an increasing focus on blue hydrogen to mitigate carbon emissions during hydrogen production. However, the commercialization of blue hydrogen production (BHP) is hindered by the challenges of high cost and energy consumption. This study proposes a new configuration to address these challenges, which is characterized by: (a) the use of piperazine (PZ) as a solvent, which has a high CO2 absorption efficiency; (b) a more efficient heat exchange configuration which recovers the waste exergy from flue gas; (c) the advanced flash stripper (AFS) was adopted to reduce the capital cost due to its simpler stripper configuration. In addition, the technical and economic performance of the proposed energy and cost-saving blue hydrogen production (ECSB) process is investigated and compared with the standard SMR process. The detailed models of the SMR process and the post-combustion carbon capture (PCC) process were developed and integrated in Aspen plus® V11. The results of the technical analysis showed that the ECSB process with 30 wt.% PZ achieves a 36.3 % reduction in energy penalty when compared to the standard process with 30 wt.% Monoethanolamine (MEA). The results of the economic analysis showed that the lowest levelized cost of blue hydrogen (LCBH) was achieved by the ECSB process with 30 wt.% PZ. Compared to the BHP process with 30 wt.% MEA, the LCBH was reduced by 19.7 %.

Simulation of Olive Pomace Gasification for Hydrogen Production Using Aspen Plus: Case Study Lebanon

Biomass is a renewable energy source gaining attention for its potential to replace fossil fuels. Biomass gasification can produce hydrogen-rich gas, offering an environmentally friendly fuel for power generation, transportation, and industry. Hydrogen is a promising energy carrier due to its high energy density, low greenhouse gas emissions, and versatility. This study aims to develop a hydrogen generation plant using a dual fluidized bed gasifier, which employs steam as a gasifying agent, to convert olive pomace waste from the Lebanese olive oil industry into hydrogen. The process is simulated using Aspen Plus and Fortran coding, and it includes a drying unit, gasification unit, gas cleaning unit, steam methane reformer unit, water–gas shift reactor unit, and a pressure swing adsorption unit. The generated gas composition is verified against previous research. Sensitivity analyses are conducted to investigate the impacts of the steam-to-biomass ratio (STBR) and gasification temperature on gas composition, demonstrating a valid STBR range of 0.5 to 1 and a reasonable gasification temperature range of 700 °C to 800 °C. Further sensitivity analyses assess the impact of reformer temperature and the steam-to-carbon ratio (S/C) on the gas composition leaving the steam methane reformer.

The state of the market of hydrogen raw materials in Russia and the world

The study analyses the current state and prospects of hydrogen energy and its impact on macro- and microeconomic indicators both development in Russia and in the world as a whole. The article describes the most promising hydrogen production methods as the ne west renewable energy resource such as electrolysis, steam reforming of methane, coal gasification, and pyrolysis. The countries that have achieved the most significant results in scientific development and technological production of hydrogen for its further utilization have been highlighted. Based on the analysis of hydrogen energy development concepts adopted in developed countries (China, Japan, India, and European Union countries), a hydrogen energy development detailed forecast for each country highlighted in the article has been made. Special attention has been paid to the concept of hydrogen energy development in Russia, approved by M. V. Mishustin on August 5, 2021. Possible ways of hydrogen energy development in Russia have been analyzed. A detailed forecast of hydrogen energy development in the world up to 2030 based on the hydrogen raw materials import and export analysis results carried out by the leading countries of the world has been presented. The risks have been listed, as well as the requirements for problem solving in implementing projects to introduce hydrogen into the energy balance of Russia.

An Economic Analysis of In-Situ Hydrogen Production from Natural Gas Wells with Subsurface Carbon Retention

Summary An economic analysis for a wellbore methodology that promotes sustainable natural gas conversion to hydrogen is presented. The methodology uses at-source, wellbore gasification of methane for hydrogen production, incorporating the simultaneous in-situ sequestration of carbon for both climate and economic benefit. The proposal is for a wellbore completion tool, to take natural gas (methane) production from the reservoir and perform gasification within the wellbore tool (not within the reservoir). This would not interfere with reservoir management, allowing standard reservoir management practices to be used. The proposed process is for natural gas fields and not for use in the gasification of heavy oils (which is covered by other “combustion type” reservoir management processes performed deep within the reservoir geology). The proposed methane gasification tool, when located deep within the wellbore, takes maximum advantage of the “free” energy provided by the elevated temperatures and pressures of the surrounding fluid-connected geology. The combination of surface-injected fluids and geofluids, mixed inside the wellbore gasification tool at depth, significantly reduces the excess process energy input from the surface and lessens feedstock consumption for power. The proposed system is neither electricity cost dependent nor fuel cost dependent, as both are provided in situ and through heat recovery and reserves. There are therefore several process steps and significant energy and cost savings to be gained by this method when compared with surface-based methane reformation facilities, as well as infrastructure longevity benefits. In addition, CO2 life cycle climate savings are made, as zero carbon is produced to the surface, eliminating the harm greenhouse gases (GHGs: CH4 and CO2) do while transitioning through the environment. The proposed methodology therefore avoids the expense and energy consumption of the subsequent, only partial, downstream recapture of the CO2 released from the combustion of this same methane. To help maintain consistency and ensure comparability for hydrogen production types, the standardized H2A template of the National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy was used in our analysis. This economic template contains several cost model scenarios used to illustrate the possible magnitudes of economic advantages using this wellbore methodology. Based on the model’s comparative cost analyses, such a proposed system could produce hydrogen from natural gas wells consistently below 1 USD/kg H2, leading to cost-competitive wellbore hydrogen production when compared with surface-based steam methane reformation facilities. Using several scenarios for cost analysis, we found that the cost cannot be higher than 2 USD/kg H2. In our uncertainty quantification, we included the effects of the number of wells that can be used as well as mixing H2 with CH4 (v/v%).

Study on tritium permeation behavior in primary and second circuits of the hydrogen production system by methane steam reforming using HTGR

Hydrogen production by methane steam reforming (MSR) using the process heat from High-temperature gas-cooled reactor (HTGR) is one of the most promising technology for hydrogen production using nuclear energy in the near future. The permeation behavior of tritium produced by the reactor is extremely important when analyzing the safety of this hydrogen production system. There are two methods of connection between a nuclear reactor and a hydrogen production system. One is direct coupling that the steam reformer of the hydrogen production system is directly connected to the first circuit of the nuclear reactor. The other is indirect coupling via an intermediate heat exchanger (IHX) to connect nuclear reactor and hydrogen production system. Hence, this work proposed a model to analyze the difference in tritium permeation between these two coupling ways and to compare the tritium permeation behavior for different IHX alloys at various operating conditions. This model includes tritium's production rate, release fraction, and decay reduction in the system. The results show that the pre-exponential factor of the IHX alloy mainly limits the tritium permeation rate. In addition, the tritium permeation rate increases about two times when the temperature rises from 750 °C to 950 °C at a steady state. Further, the decrease of tritium permeation rate is seen from the calculation results for the system with IHX, e.g., for T = 750 °C, the mean permeation rate of tritium into the product gas is 9.31 × 10−12 mol/s at the whole year for indirect coupling with an IHX, compared to 3.86 × 10−12 mol/s for direct coupling, which reduced 58.54 % (This means that with IHX the permeation rate is lower than the system without IHX). These results will contribute to designing an effective and safe hydrogen production system by MSR using HTGR process heat.

Multi-objective optimization of steam methane reformer in micro chemically recuperated gas turbine

A kinetic theory, known as the Langmuir–Hinshelwood–Hougen–Watson adsorption model, is applied to describe the steam methane reforming (SMR) in a 500 kW scale micro chemically recuperated gas turbine (CRGT) cycle. The response surface models of important performance parameters, including the methane conversion, carbon monoxide selectivity, and chemically recuperated heat as a function of the temperature, pressure, steam-to-carbon ratio, and contact time are numerically obtained based on the cases selected by the central composite design. The factors affecting the SMR performance are analyzed, and the reformer performance is optimized using both the desirability function combined with the response surface methodology and the second generation non-dominated sorting genetic algorithm. Finally, performance of the optimized reformer and electrical efficiency of the micro CRGT cycle with the reformer are evaluated. Results reveal that the efficiency of the micro CRGT is 40.70%, which is much higher than the typical high-efficiency micro gas trubine without reformer.

Methane catalytic cracking by solid materials and molten media for hydrogen production: A review

Excessive emission of carbon dioxide is the leading cause of global warming. Hydrogen has the advantages of high calorific value and zero carbon emissions. It is considered an ideal energy to solve the problem of global warming, so the demand for hydrogen is increasing yearly. Due to economic considerations, methane is the main raw material for hydrogen production. Currently, 48% of the world's hydrogen comes from steam methane reforming. However, this process needs to burn some methane for heating, generating carbon dioxide emissions simultaneously. In order to avoid carbon emissions from hydrogen production, there is an urgent need to develop new methods to produce hydrogen from methane. Because the carbon generated from direct methane cracking exists in solid form while not as carbon dioxide, the direct methane cracking process for hydrogen production has become a hot research topic in recent years. In this paper, a comprehensive review of the research related to catalytic methane cracking for hydrogen production is presented, especially the research on catalytic cracking of methane using solid materials or molten metal media as catalytic media is summarized in detail. Next, a brief overview of the mechanism of catalytic methane cracking for hydrogen production and the characteristics of the generated carbon as a by-product are presented. Finally, the catalytic cracking of methane in molten media or solid materials and the research trend were prospected.

High-Throughput Screening of Sulfur-Resistant Catalysts for Steam Methane Reforming Using Machine Learning and Microkinetic Modeling.

The catalytic activity of bimetallic catalysts for the steam methane reforming (SMR) reaction was extensively studied previously. However, the performance of these materials in the presence of sulfur-containing species is yet to be investigated. In this study, we propose a novel process aided by machine learning (ML) and microkinetic modeling for the rapid screening of sulfur-resistant bimetallic catalysts. First, various ML models were developed to predict atomic adsorption energies (C, H, O, and S) on bimetallic surfaces. Easily accessible physical and chemical properties of the metals and adsorbates were used as input features. The Ensemble learning, artificial neural network, and support vector regression models achieved the best performance with R2 values of 0.74, 0.71, and 0.70, respectively. A microkinetic model was then built based on the elementary steps of the SMR reaction. Finally, the microkinetic model, together with the atomic adsorption energies predicted by the Ensemble model, were used to screen over 500 bimetallic materials. Four Ge-based alloys (Ge3Cu1, Ge3Ni1, Ge3Co1, and Ge3Fe1) and the Ni3Cu1 alloy were identified as promising and cost-effective sulfur-resistant catalysts.

Levelized Cost of Biohydrogen from Steam Reforming of Biomethane with Carbon Capture and Storage (Golden Hydrogen)—Application to Spain

The production of biohydrogen with negative CO2 emissions through the steam methane reforming of biomethane, coupled with carbon capture and storage, represents a promising technology, particularly for industries that are difficult to electrify. In spite of the maturity of this technology, which is currently employed in the production of grey and blue hydrogen, a detailed cost model that considers the entire supply chain is lacking in the literature. This study addresses this gap by applying correlations derived from actual facilities producing grey and blue hydrogen to calculate the CAPEX, while exploring various feedstock combinations for biogas generation to assess the OPEX. The analysis also includes logistic aspects, such as decentralised biogas production and the transportation and storage of CO2. The levelized cost of golden hydrogen is estimated to range from EUR 1.84 to 2.88/kg, compared to EUR 1.47/kg for grey hydrogen and EUR 1.93/kg for blue hydrogen, assuming a natural gas cost of EUR 25/MWh and excluding the CO2 tax. This range increases to between 3.84 and 2.92, with a natural gas cost of EUR 40/MWh with the inclusion of the CO2 tax. A comparison with conventional green hydrogen is performed, highlighting both prices and potential, thereby offering valuable information for decision-making.

Feasibility assessment of transition metal carbides applied to chemical looping reforming – A proof-of-concept for tungsten carbide

This paper is the first study to present an innovative technology for hydrogen and syngas production named Carbide Chemical Looping Reforming (CCLR). Nine different Transition Metal Carbides (TMC) were assessed in a thermodynamic study to evaluate potential materials to be applied in the system that could possibly form hydrogen and carbide when in the presence of methane. Out of all the materials, tungsten proved to be the best suitable due to its known high resistance to carbon deposits [1], low-temperature range to form carbides (at least 750 °C), no formation of undesired compounds, and considerably high hydrogen quality in syngas range. A sensitivity analysis is performed in order to assess the better conditions of temperature, pressure and methane ratio for the process to maximize the formation of hydrogen. A study of the heat balance between the air reactor and fuel reactor is shown to prove the system can work as an autothermal process and exclude external heat sources as well as an analysis of the carbon emission potential to prove the technology accounts for lower emission when compared to current technologies, such as Steam Methane Reforming and Steam Methane Reforming with Carbon Capture and Storage. Experimental thermogravimetric analysis showed a high formation of hydrogen and carbide in the system with high selectivity towards hydrogen/syngas reactions, proving the formation of carbides in a process and replicability of the system. Lastly, an economic assessment is performed with tungsten carbide to show that the application of tungsten in CCLR could achieve a competitive level to current technologies with a hydrogen cost price of USD 3.23, with the potential to be reduced even more depending on the process configuration.

Significant improvement of both hydrogen permeation and catalytic activity of nickel hollow fiber membrane reactor by surface electrochemical modification

We developed a novel approach to modify the nickel hollow fiber membrane (NHFM) for enhanced H2 permeation and catalytic activity. In this work, the outer dense layer of the manufactured NHFM was precisely removed by surface electrochemical modification. A porous structure was formed on the membrane surface after the removal of the outer dense layer, but the inner dense layer still maintained intact. Compared to the raw membrane, not only H2 permeation of the modified membrane increased by approximately 2 times in the separation test, but also the catalytic activity of the modified membrane increased by 5 ∼ 7 times in the methane steam reforming (MSR) reaction test. Acid etching, electrochemical etching with various electrolyte solutions was comparably investigated for the removal of the outer dense layer. Acid etching showed low effectiveness and uneven surface modification as the etching process starts from the grain boundary. Electrochemical etching showed higher efficiency to achieve a uniform modification in a shorter etching time. Among the three investigated electrolytes, namely H2SO4, HCl and HNO3, H2SO4 had the best performance due to its complete remove of the outer dense layer and the formation of a uniform open porous structure on the membrane surface. The removal of the outer dense layer reduces mass transfer resistance for hydrogen permeation and allowed the formation of open porous structure to increase the specific surface area for more reaction catalytic sites. It is a highly efficient technique to improve both hydrogen permeation and catalytic activity for NHFM reactors.

Thermodynamic model: steam and oxidative reforming of methane over nickel catalyst

In this paper, we have used a thermodynamic model for the first time to investigate the steam and oxidative reforming of methane over a nickel catalyst in a wide temperature range, i.e., 400–1200 K. The available literature focus on the kinetic models and hence, thermodynamic models require attention to understand the behaviour of the thermochemistry of the species involved in the mechanism. This study presents the comparison between the species concentration produced using the thermodynamic model against the available kinetic model to validate the results. The investigation is further extended, firstly, to perform the sensitivity analysis of the reactions involved in a thermodynamic model to figure out the most influential reactions at various temperatures and pressures. This allows us to compare the most influencing reactions in reforming process for kinetic and thermodynamic model to optimize the processes. Secondly, the reaction flow analysis is carried out for the thermodynamic model to comprehend the effect of the thermochemistry of the species and the major difference in the reaction pathways for both the models are noted.