Steam Reforming Research Articles

Research Progress on Characteristics of On‐Line Hydrogen Production by Methanol Steam Reforming

On‐line hydrogen production via methanol steam reforming (MSR) has gained considerable interest due to its high efficiency, affordability, and eco‐friendliness. Currently, this technology has been widely applied in the industry and has become an important method for hydrogen energy production. However, there are still some issues with this technology, such as short catalyst lifespan and CO pollution, which require further research and improvement. This article provides a comprehensive review of the research progress made in this field, with a particular focus on the catalyst development, reaction mechanism, theoretical calculation, and reactor design. Additionally, the challenges and prospects of on‐line hydrogen production by MSR are also discussed. In conclusion, MSR technology for hydrogen production has vast application prospects and development potential. It will be further explored in‐depth and extensively in future research.

Predicting nickel catalyst deactivation in biogas steam and dry reforming for hydrogen production using machine learning

This study employs Random Forests (RF) and Artificial Neural Networks (ANN) to model the transient behavior of Ni catalyst deactivation during steam and dry reforming of model biogas containing H2S, with a focus on hydrogen production. Deactivation, induced by carbon deposition and sulfur poisoning, is a complex and transient phenomenon demanding precise kinetic mechanisms for accurately predicting Ni catalyst behavior in biogas reforming. Black-box machine learning (ML) models are developed, incorporating catalyst properties, biogas composition, and operating conditions. Encompassing both dry and steam reforming, the ML models aim to predict catalyst behavior, expressed in terms of packed bed reactor exit mole fractions (H2, CO, CH4, and CO2) and conversions (CH4 and CO2). The ML models are trained and tested across a temperature range of 700–900 C with 0–145 ppm of H2S in model biogas (CH4/CO2 ratio varying from 1.0 to 2.0). RF outperforms the ANN across all performance metrics, including overall R2 and root mean squared error (RMSE). The RF achieves a mean overall R2 of 0.979, with training and testing RMSE equal to 6.7×10−3 and 1.47×10−2 respectively. In contrast, the ANN achieves a mean overall R2 of 0.939, with training and testing RMSE equal to 2.6×10−2 and 2.55×10−2 respectively. Moreover, pre-trained RF models are validated with unseen data of dry reforming of biogas containing 30 ppm of H2S (25 data points). It is suggested that 35 % of this unseen experimental data is required to train the RF model for it to predict catalyst deactivation, achieving a validation R sufficiently2> 0.9. The mean overall R2 values attained by the RF fine-tuned on 35 % of the unseen experiment data for both CH4 and CO2 conversions, as well as for all mole fraction predictions, are 0.952 and 0.948, respectively.

Extraction of sustainable and low-emission hydrogen from hydrogen-blended natural gas driven by multi-product sequential separation

Blending hydrogen in natural gas, taking advantage of the readily available pipeline transportation, is considered as a highly promising means of sustainable hydrogen deployment on a vast scale. However, re-obtaining hydrogen from the mixture for end users via conventional separation technologies could pose practical challenges both energetically and economically, due primarily to the relatively low blending ratio (<30 vol%). In contrast to the commonly adopted pressure swing adsorption (PSA) separation, we propose a thermochemical approach of deriving hydrogen with synergistic capture of CO2 by steam reforming of the mixture to tackle such challenges. The process is simulated by a two-dimensional model validated by experimental data. Three typical scenarios with hydrogen blending ratios of 0–30 vol% are investigated in the operating temperature range of 300–400 °C and natural gas pipeline pressure of ≤ 40 bar. Results show that in all scenarios the amount of hydrogen recovered can exceed the amount of renewable hydrogen initially blended and additional hydrogen could be contributed thermochemically, all at relatively low energy cost. Thermochemical methods increase the partial pressure of target products, reducing separation energy and increasing yield. For the typical 10 vol% blending ratio (widely adopted), when considering the separation of hydrogen at the end user and compressing the separated off-gas before transporting it to the next end user, the hydrogen separation cost, after counterbalancing with the revenue from carbon dioxide, is only 1.33$/kgH2 with the new approach. This corresponds to a decrease by over 70.2 % as compared with that of the PSA separation cost (4.45$/kgH2). The captured CO2 in its high-purity form helps to reduce the final cost of hydrogen by a maximum of 0.33$/kgH2. The new route shows great potential for integrated hydrogen production, hydrogen purification and carbon capture for the promotion of renewable energy, green hydrogen and related technologies.

Numerical analysis of catalytic reaction kinetics in methanol steam reformer with variable cross-sectional channel

ABSTRACT Methanol steam reforming (MSR) is a hydrogen production method recognized for its low harmful emissions and high cost-effectiveness. In this study, a three-dimensional numerical model of MSR within channels of variable cross-section. A quantitative relationship between local equilibrium constants and channel structural parameters was established based on the partial pressures of the components. Additionally, the mechanisms by which variable cross-sectional channel structural parameters regulate MSR reaction performance were quantitatively analyzed, considering fluid dynamics, hydrogen production efficiency, and chemical kinetics rates. The results indicate that the kinetic rate of MSR and local equilibrium constants are significantly influenced by the modulation of variable cross-sectional channel structural parameters, with a maximum variation of 50.6%. A positive correlation between methanol conversion rate and the local equilibrium constant of MSR was observed. Utilizing channel structural parameters to enhance MSR led to an 8.75% increase in methanol conversion rate within the same reaction volume. These conclusions may provide theoretical support for regulating volumetric reactions through variable cross-sectional channel structural parameters.

Multiscale modeling of catalyst deactivation in dry methane reforming

Dry methane reforming (DRM) presents a promising strategy to convert greenhouse gases (CH4 and CO2) into syngas, a valuable precursor for the production of long-chain alkanes. However, catalyst deactivation remains a major issue, primarily caused by the deep cracking of CH4 and CO2 as well as the metal-catalyzed growth of carbon whiskers. To address this challenge, we introduce a multiscale model that analyzes DRM reactions on the Ni surface and predicts whisker formation. The multiscale modeling approach integrates microscopic kinetic Monte Carlo (kMC) simulations for surface reactions, mesoscopic pellet-scale modeling for predicting whisker growth length and macroscopic modeling to consider packed bed porosity and pressure drop across the reactor. Further, by systematically introducing time-steppers using the gap-tooth scheme, we significantly improved the computational efficiency, reducing the computational time from 17 days to 6 h at the expense of minimal accuracy loss in predicting whisker length. Based on this, we assert that such a multiscale model enables the analysis of various operating conditions affecting catalyst deactivation and kinetics of surface reaction, aiding in the design and optimization of DRM process.

Efficient Hydrogen Production by Combined Reforming of Methane over Perovskite-Derived Promoted Ni Catalysts

Efficient Hydrogen Production by Combined Reforming of Methane over Perovskite-Derived Promoted Ni Catalysts

Highly Stable Ni-B/Honeycomb-Structural Al2O3 Catalysts for Dry Reforming of Methane.

Two-component catalysts have garnered significant attention in the field of catalysis due to their ability to inhibit Ni sintering. In the present work, honeycomb-structuralstructured Al2O3-supported Ni and B were prepared to enhance coke tolerance during dry reforming of methane (DRM). Transmission electron microscopy (TEM) results revealed that the average particle sizes on Ni/Al2O3 and Ni-0.16B/Al2O3 were 7.6 nm and 4.2 nm, respectively, indicating that B can effectively inhibit Ni sintering. After a 100-hour reaction, the conversion of CH4 and CO2 on Ni/Al2O3 decreased by approximately 5 %, whereas on Ni-0.16B/Al2O3, there was no significant decrease in CH4 and CO2 conversion, with values of approximately 81.6 % and 87.2 %, respectively. In situ DRIFT spectra demonstrated that Ni-0.16B/Al2O3 enhanced the activation of CO2, thus improving the catalyst's stability. A Langmuir-Hinshelwood-Hougen-Watson (LHHW) model was developed for intrinsic kinetics, and the resulting kinetic expressions were well-fitted fit to the experimental data, with R2 values exceeding 0.9. ActivationThe activation energies were also calculated. The outstanding stability of Ni-0.16B/Al2O3 can be attributed to its stable honeycomb structure and B's ability to significantly inhibit Ni sintering, reduce catalyst particle size, and enhance coke tolerance.

Optimization of a novel hydrogen production process integrating biomass and sorption-enhanced reforming for reduced CO2 emissions

Recently, there has been a growing demand for clean and sustainable energy sources to bridge the energy gap. Hydrogen has emerged as an attractive and environmentally friendly energy carrier due to its potential for high energy efficiency and minimal pollution generation, making it a promising alternative to fossil fuels. This study proposes and investigates a novel coupled process that utilizes chemical looping technologies for hydrogen production, simultaneously utilizing natural gas and biomass as feedstocks. The primary objective of this research is to develop a process model that maximizes hydrogen production while minimizing carbon dioxide emissions. Aspen Plus version 10 was employed to simulate and analyze the proposed process configuration to achieve this. One of the proposed process's key advantages is its competitiveness compared to conventional steam methane reforming (SMR) processes, which are widely used in industry. The novel process offers significant benefits, such as enhanced hydrogen purity and reduced CO2 content in the product gas. The simulation results obtained from Aspen Plus reveal the successful production of highly pure hydrogen with a molar ratio of H2/CO equal to 268 and syngas with a molar ratio of H2/CO approximately equal to 1. Additionally, the process demonstrates the capability to produce highly high-purity hydrogen with a molar ratio of H2/CO equal to 155,000 in three-section reactors.

DFT insights into oxygen vacancy formation and chemical looping dry reforming of methane on metal-substituted CeO2 (111) surface

DFT insights into oxygen vacancy formation and chemical looping dry reforming of methane on metal-substituted CeO2 (111) surface

Amorphization-sparked superb activity and excellent coke-resistance of Ni nanocatalyst

Selective conversion of CH4 and CO2 to syngas via the dry reforming reaction is highly desirable in terms of restraining the greenhouse effect and meanwhile acquiring useful chemicals. However, the most promising Ni catalysts for the reaction still suffer from severe coking and thus poor durability. Here, we report that using amorphous Ni nanoparticles synthesized on an N modified mesoporous silica support, the catalytic activity and coke-resistant performance of Ni toward the photothermal dry reforming of methane (DRM) are greatly improved. Theoretical calculations further unveil that the amorphous Ni nanoparticles are much more energetically favorable to activate the CH4 and CO2 molecules as well as to remove the C* intermediates for coke formation than their crystalline Ni counterparts, which renders the amorphous Ni nanoparticles with both superb activity and excellent coke-resisting property. This finding possibly provides a new avenue to make both highly efficient and anti-coking catalysts for the DRM reaction and beyond via facile amorphization of active metals.

Regulating N-Cu/MoxC interfacial effect coupling β-Mo2C/γ-MoC phase engineering to achieve efficient hydrolysis dissociation and methanol dehydrogenation for hydrogen production

Methanol steam reforming (MSR) is a promising solution for achieving the integration of hydrogen storage, transportation, and in-situ supply. However, it is limited by the slow rate of hydrogen generation and low selectivity. This study constructed a highly active N-Cu/MoxC catalyst with strong interaction between Cu and MoxC, effectively enhancing methanol activation, hydrolysis, and hydrogen production efficiency. Under optimized condition, the 2.8 N-Cu/MoxC catalyst achieved a remarkable H2 productivity of 147.9 mmol gcat−1 h−1 and H2 selectivity of 65.7 %. N induced a partial transition from β-Mo2C phase to γ-MoC phase, resulting in a doubling of H2 production rate. The interfacial N-Cu-MoxC sites facilitated highly reactive efficient CH bond dissociation to convert CO+4H and OH activation, as well as the highly efficient CO reforming. Additionally, temperature programmed surface reaction and isotope testing futher coroborated its superiority in methanol dehydrogenation and hydrolysis dissociation. These discoveries can provide guidance for the design of advanced MSR catalysts.

Study on Ce-MOF-derived oxides as morphology-tunable catalyst supports for dry reforming of methane

Dry reforming of methane (DRM) using CH4 and CO2 as feedstocks to catalytically produce high-value synthesis gas products has great application prospects. However, as a high-temperature heterogeneous catalytic reaction, the challenge lies in preparing efficient and stable catalysts for long-term operation. To enhance the catalytic performance by optimizing support, this study proposed regulating the catalyst structure and properties using Ce-based metal-organic framework (MOF) derivatives. Compared with the conventional Ni/CeO2, Ni/CeO2-MOF catalysts performed better in DRM. Especially, Ni/CeO2-UiO-66 demonstrated significant improvement in both catalytic activity and stability. It was also noticed that the Ni/CeO2-MOF catalysts had a potential benefit in limiting the conversion of carbon species to inactive forms given the relatively lower carbon gasification temperatures at their surfaces. The advantage of Ni/CeO2-MOF catalysts was attributed to their better void structure and reduction characteristics, as well as higher oxygen vacancy concentration and improved CO2 adsorption activation capability after pre-activation. This study revealed that MOF-derived supports had distinctive structural characteristics, which were manifested as an important component in high-temperature catalyst systems.

Nickel silicate CHA-type zeolite prepared by interzeolite transformation and its catalytic activity in dry reforming of methane

We newly synthesized the nickel silicate CHA-type zeolitic material (Ni-CHA) through the interzeolite transformation of the parent nickel silicate MWW-type zeolite (Ni-MWW) using the structure-directing ability of N,N,N-trimethyl-1-adamantammonium hydroxide. With increasing crystallization time under hydrothermal conditions, the parent Ni-MWW was decomposed into an X-ray amorphized nickel silicate, which was then consecutively reassembled into Ni-CHA. Furthermore, as the crystallization progressed, the framework Ni species gradually transformed from intermediate Ni to isolated Ni species, achieving a more thermodynamically stable chemical state. The metallic Ni clusters can be formed by exsolving from the CHA framework during the high-temperature reduction treatment, which were mainly distributed on the external surface. A series of in-situ reduced Ni-CHA-x catalysts obtained after different crystallization times (x = 0–72 h) were applied to the dry reforming of methane to evaluate their catalytic activity corresponding to the differences in crystallinity and chemical state. As a result, the interzeolite transformed Ni-CHA-72 h catalyst exhibited the highest catalytic performance even compared to the Ni-impregnated commercial SSZ-13.

Influence of the Interaction of Nickel and Copper with Ceria on Ethanol Steam Reforming over Ni-Cu-CeO2 Catalysts

Catalysts of nickel-ceria, nickel-copper-ceria, and copper-ceria were explored with respect to their properties for hydrogen production through ethanol steam reforming (ESR). They were prepared by coprecipitation of the components within inverse microemulsions to achieve intimate contact between them, and the catalysts were characterized by N2 adsorption measurements, XRD, Raman spectroscopy, TPR, and XPS. The catalysts were tested for the ESR reaction, and they were regenerated with oxygen when significant deactivation took place, as occurred for the copper-containing systems. In contrast, the nickel–ceria catalyst exhibits a high activity and stability despite the formation of an important amount of carbon deposits during the course of the ESR test. The presence of nickel sites, which strongly interact with the ceria support, and which are affected by the presence of copper, and the limitation of copper for C-C bond breaking are invoked to explain the results obtained on the whole.

Reforming of methane over two-dimensional Mo2C-Ni/γ-Al2O3 catalyst

The impact of two-dimensional Mo2C (2D-Mo2C) on the activity and stability of a Ni/γ-Al2O3 catalyst for the dry reforming of methane (DRM) is reported. 1.1 wt% 2D-Mo2C added to 13 wt% Ni/γ-Al2O3 increased activity by ∼40 %. Characterization results showed an interaction between 2D-Mo2C and Ni that resulted in the formation of a NixMoy bulk phase (XRD) and Ni-Mo-oxycarbide surface species (XPS). The presence of 2D-Mo2C also improved the stability of the catalyst compared to Ni/γ-Al2O3 by reducing coke deposition. H2 space-time-yields (STYs) were independent of CO2 partial pressure and were lower than the CO STYs. Power law kinetic models were consistent with a DRM reaction pathway via CH4 decomposition (MD) and the reverse Boudouard (RBD) reactions.

The Role of Catalysts in Life Cycle Assessment Applied to Biogas Reforming

The real implementation of biogas reforming at an industrial scale to obtain interesting products (like hydrogen or syngas) is a developing research field where multidisciplinary teams are continuously adding improvements and innovative technologies. These works can contribute to the proliferation of green technologies where the circular economy and sustainability are key points. To assess the sustainability of these processes, there are different tools like life cycle assessment (LCA), which involves a complete procedure where even small details count to consider a certain technology sustainable or not. The aim of this work was to review works where LCA is applied to different aspects of biogas reforming, focusing on the role of catalysts, which are essential to improve the efficiency of a certain process but can also contribute to its environmental impact. In conclusion, catalysts have an influence on LCA through the improvement of catalytic performance and the impact of their production, whereas other aspects related to biogas or methane reforming could equally affect their catalytic durability or reusability, with a subsequent effect on LCA. Further research about this subject is required, as this is a continuously changing technology with plenty of possibilities, in order to homogenize this research field.

Design and multi-objective optimization of hybrid process of membrane separation and electrochemical hydrogen pump for hydrogen production from biogas

A new hybrid process for hydrogen (H2) production that including membrane separation, electrochemical hydrogen pump (EHP) and steam methane reforming (SMR) was proposed. Firstly, the combination of two different membranes (PEO-CA) is applied to upgrade the biogas and capture CO2. Secondly, to avoid the toxic effect of CO on the EHP catalyst and, more importantly, to improve the H2 purity, the reforming reaction module is supplemented with water gas shift after the SMR. Finally, EHP is used to achieve high purity hydrogen. Simultaneously, the heat and power integration are considered to improve system efficiency. Sensitivity analysis, maximal information coefficient method and response surface methodology are applied to establish the correlation between objectives and parameters. Then, the second generation multi-objective non-dominated genetic algorithm (NSGA-II) is utilized to achieve minimum levelized cost of hydrogen (LCoH) and carbon emission per unit of hydrogen (ECO2). The optimized LCoH is 2.72 $/kgH2, and the ECO2 is 3.24 kgCO2e. Multi-stage membrane carbon capture process enhances CH4 conversion in SMR. The application of EHP reduces energy consumption and enhances hydrogen yield compared to PSA. The innovative use of membrane is hybridized with EHP to achieve the system intensification. The new hybrid process has a significant advantage in terms of ECO2 (37.45% reduction), although the price is higher compared to conventional biogas-to-hydrogen processes. Thus the new process is a promising low-carbon hydrogen production process from biogas.

Techno-economic assessment of gasoline production from Fe-assisted lignocellulosic biomass hydrothermal liquefaction process with minimized waste stream

Techno-economic analyses were conducted on an iron-assisted hydrothermal liquefaction (HTL) process for converting lignocellulosic biomass into gasoline, comparing two approaches for minimizing by-product streams. The primary difference between the two approaches lies in their hydrogen (H₂) source for upgrading bio-crude to bio-gasoline. Scheme 1 utilizes residual water-soluble and gaseous compounds from the process to generate the H₂ needed for upgrading. Scheme 2, on the other hand, converts these waste streams into heat to supply part of the required energy, while external H₂ from steam methane reforming (with or without CO₂ capture) or water electrolysis (green hydrogen) is used for upgrading. Both schemes use pinewood and red mud as feedstocks. Red mud, after the reduction of Fe₂O3 to metallic iron, is employed in the HTL reactor as a hydrogen producer, enhancing both the yield and quality of the bio-crude while minimizing the H2 consumption in the upgrading unit. The HTL reactor was modeled based on optimal operating conditions experimentally determined while sensitivity analyses were performed on the other scheme’s units to determine their optimal conditions. A Life Cycle Assessment (LCA) was also conducted to measure the environmental impact of the two scenarios.Both schemes produce 459 tonnes of gasoline equivalent per day, consuming 33 tonnes of H2. Scheme 2 achieves a minimum fuel selling price (MFSP) of $0.94 per liter of gasoline equivalent (LGE), with methane reforming and CO₂ capture providing the lowest emissions (1.13 kg CO₂-Eq per kg of LGE). Scheme 1 has a slightly higher MFSP of $0.96 per LGE but is more environmentally sustainable, with a LCA showing 1.11 kg CO₂-Eq per kg of LGE.

Co–Fe/Al2O3 catalyst for low-temperature steam reforming of phenol for hydrogen production

In this study, a series of high-efficient catalyst, Co–Fe/Al2O3, were synthesized via the sol-gel method for low-temperature phenol steam reforming (PSR). The optimized catalyst, 15Co–2Fe/Al2O3, exhibited a remarkable phenol conversion of 95.3%, a H2 yield of 92.1% at 450 °C, GHSV = 7500 h−1 and a steam-to-carbon (S/C) ratio of 10. Furthermore, the catalyst activity was maintained for 660 min before a gradual decline was observed. The NH3-TPD analysis revealed that the addition of Fe enhanced the surface acidity of the catalyst, providing more active sites for phenol adsorption and activation. This study aims to address the challenges associated with high reaction temperatures and poor catalyst stability in PSR. Various characterization techniques have been employed to investigate the reaction mechanisms of bimetallic catalysts in low-temperature PSR.

Exploring the superior mild temperature performance of nickel-infused fibrous titania silica for enhanced dry reforming of methane

Carbon (IV) oxide (CO2) and methane (CH4) contribute significantly to greenhouse gas emissions and global warming. One potential approach for reducing their environmental impact is transforming these gases into synthesis gas (CO + H2). This study illustrates the advancement of catalysts supported by fibrous titania silica (FTS), which have nickel loadings of 1%, 3%, and 5%. The FTS support, a modified variant of silica-titania, has a distinct fibrous structure and exhibits mesoporous material properties such as a type IV isotherm and an H1 hysteresis loop. After 72 h of operation, the 1Ni/FTS catalyst converted over 80% of CH4 and CO2 with low coke deposition, outperforming other catalysts. The bare FTS support had reduced CH4 conversion at 600°C, CO2 conversion at 650°C, and H2/CO ratio at 700°C. However, the 5Ni/FTS and 3Ni/FTS catalysts showed consistent increases in CH4 conversion at 600°C. The 1Ni/FTS catalyst, with a pore size of 7.39 nm, had strong metal-support interaction and moderate basicity sites, which helped with reactant dissociation and coke gasification. Despite the slightly higher CH4 conversion of the 3Ni/FTS catalyst and the high basicity of the 5Ni/FTS catalyst, the 1Ni/FTS catalyst demonstrated superior thermal stability and coking resistance, as evidenced by negligible weight loss during TGA analysis. Raman shifts revealed the presence of carbon synthesis and the buildup of disordered amorphous carbon. The Id/Ig ratios of FTS, 1Ni/FTS, 3Ni/FTS, and 5Ni/FTS were 1.01, 0.98, 1.01, and 1.01, respectively. The lower Id/Ig ratio of 1Ni/FTS suggests less disorder. The FTS support promises mild-temperature, carbon-neutral CH4 reforming with long-term catalytic applications. This study demonstrates the efficacy of FTS-supported catalysts in constructing long-term and efficient systems for converting greenhouse gasses.