Catalysts For Steam Reforming Research Articles

Noble metal (Pt, Pd and Rh) promoted Ni-Co/Mg(Al)O catalysts for steam reforming of tar impurities from biomass gasification

Steam reforming is a promising approach to remove biomass gasification tar impurities. Noble metal promotion (Pt/Pd/Rh), Ni+Co loading (20–40 wt%) and calcination temperature (600–800 °C) effects were investigated with hydrotalcite-derived Ni-Co/Mg(Al)O catalysts for bio-syngas tar steam reforming. Fresh catalysts were characterized by XRD, ICP-MS, XRF, N2-physisorption, H2-chemisorption and TPR. Small-diameter metal particles were achieved (5.1–5.8 nm) below a Ni+Co loading threshold (above 30 wt%). Model bio-syngas activity tests were performed (CH4/H2/CO/CO2 molar ratio = 10/35/25/25, 700 °C, steam-to-carbon = 3.0) with and without tar addition (toluene/1-methylenaphthalene, 10 g/Nm3). Tar elimination was achieved with all samples. Enhanced reforming activity accompanied by strong tar active site inhibition effects were found for the Rh promoted catalyst. Noble metal promoted samples were effectively reduced in the bio-syngas environment (H2/CO/CH4) without any pre-reduction (in situ activation by the action of the syngas) with Rh > Pt > Pd. Coke characterization was conducted with TPO-MS and Raman spectroscopy. High-dispersion 20NiCo/30NiCo samples were strongly deactivated through active site inhibition and coke formation. High-temperature calcination (800 °C) reduced the deactivation effects of the coke deposition, attributed to enhanced Mg(Al)O-assisted coke gasification.

METHANOL STEAM REFORMING FOR HYDROGEN PRODUCTION OVER Ni-BASED CATALYSTS: STATE-OF-THE-ART REVIEW AND FUTURE PROSPECTS.

With increasing global emphasis on environmental sustainability, the reliance on traditional energy sources such as coal, natural gas, and oil is encountering significant challenges. H2, known for its high energy content and pollution-free usage, emerges as a promising alternative. However, despite the great potential of H2, approximately 95% of hydrogen production still depends on non-renewable resources. Hence, the shift towards producing H2 from renewable sources, particularly through methods like steam reforming of methanol - a renewable resource - represents a beacon of hope for advancing sustainable energy practices. This review comprehensively examines recent advancements in efficient H2 production using Ni-based catalysts in methanol steam reforming (MSR) and proposes the future prospects. Firstly, the fundamental principles of MSR technology and the significance in clean energy generation are elucidated. Subsequently, the design, synthesis techniques, and optimization strategies for enhancing the catalytic performance of Ni-based catalysts are discussed. Through the analysis of various catalyst compositions, structural adjustments, surface active sites, and modification methods, the review uncovers effective approaches for boosting the activity and durability of MSR reactions.By offering a comprehensive critical analysis, this review serves as a valuable reference to enhance MSR hydrogen production efficiency and catalyst performance.

Effect of Lanthanum and Iron Doping on Nickel‐Based Alumina and Ceria Supported Catalysts for Steam Reforming of Methane

AbstractMembrane reformers emerge as an efficient technology for ‘on‐site’ ultra‐pure hydrogen production. The membrane reformer can be integrated with PEM fuel cell (PEMFC) to provide power. However, as the PEMFC works at lower temperature hence, such integration requires a low temperature catalyst. Further, for successful integration of membrane reformer with PEMFC, a low CO selective catalyst is vital. In current work, Ni‐based alumina and ceria supported catalysts are used. The effect of La and Fe promoters on the performance of Ni‐based alumina and ceria supported catalysts are investigated. The catalysts are synthesized using wet impregnation method. A complete characterization of catalysts is performed using BET, XRD, FESEM, and EDX. Fe promoted catalysts shows low CO and high CO2 selectivity which is desirable for membrane reformer. However, the catalytic activity of Fe promoted Ni‐based alumina and ceria supported catalysts were low. La promoted Ni‐based catalysts show high catalytic activity on both alumina and ceria supported catalysts. La promoted catalysts also gives low start up time, high catalytic activity and low CO selectivity at low temperature. Ni−La/Al2O3 catalyst provides 50 % conversion and 12 % CO selectivity at 500 °C. This makes it suitable for ‘on‐site’ generation of ultra‐pure hydrogen through membrane reformer.

Removal of silica in rice husk derived Ni/biochar modifies reaction intermediates formed and minimizes coking in steam reforming of glycerol

Metal/biochar catalyst features with the advantages for easy recovery of chemical energy of biochar carrier and metal species via simply combustion. Another unique feature of biochar carrier is intrinsic inorganic species, which might also interact with metal species in resulting catalyst. This was investigated herein by synthesis of the Ni/biochar with rice husk-derived biochar carrier pretreated with NaOH for removal of SiO2 and evaluation of the resulting catalysts in steam reforming of glycerol. The solid phase reactions between NaOH and biochar (mass ratio: 2) plus subsequent washing removed 94.6% of ash (mainly SiO2). This formed Ni/biochar of fragmented surface with specific surface area increasing from 207.8 to 457.4 m2g-1 and simultaneously increasing mesopore percentage from 15.5% to 24.0%. NaOH treatment also effectively removed significant portion of both Lewis and Brønsted acidic sites but created abundant alkaline sites. These drastically enhanced nickel dispersion and activity for steam reforming. In-situ IR characterization suggested enhanced adsorption/activation of CO2 and H2O over Ni/biochar treated with NaOH (Ni/biochar-NaOH), which mitigated accumulation of coke precursors bearing CO or CC via accelerated gasification reactions. This led to the reduced amount of coke (mass ratio to catalyst) from 193.4% to 94.7% over Ni/biochar treated with 2-fold of NaOH or to 111.3% over Ni/biochar treated with 1-fold of NaOH. The coke formed was mainly catalytic type in form of carbon nanotube over Ni/biochar-NaOH. The superior resistivity to coking originated from developed pores, enhanced Ni dispersion and abundant alkaline sites from the NaOH treatment.

Hydrolysis Precipitation Method for the Preparation of Cu‐ZnO@Al2O3 Catalyst in Methanol Steam Reforming

AbstractA hydrolysis precipitation method was developed to prepare Cu based catalyst for methanol steam reforming. A comparison of the hydrolysis precipitation and the conventional coprecipitation method was conducted. The test results present that Cu‐ZnO@Al2O3 prepared by hydrolysis precipitation exhibits better catalytic activity and stability in MSR reaction. XRD, XRF, EDS, SEM, TPR, XPS and N2 adsorption/desorption reveal that the high catalytic performance of Cu based catalyst from hydrolysis precipitation could be attributed to developed pore organization, surface enrichment of active components and higher reducibility.

The study of strong metal-support interaction enhanced PdZn alloy nanocatalysts for methanol steam reforming

Methanol steam reforming faces a significant challenge due to CO formation, which can lead to poisoning of fuel cell electrodes. This study introduces a series of Pd/ZnO catalysts prepared by ethylene glycol reduction, exhibiting remarkable selectivity in methanol steam reforming (MSR). The majority of palladium species exist in the form of PdZn alloy, attributed to the dual reduction process. This process, along with the generation of zinc vacancies and oxygen vacancies, enhances the interaction between the metal-carrier, promoting the formation of PdZn alloy, significantly improving CO2 selectivity and catalytic activity. Even at a high temperature of 400 °C, the active phase remains stable. After 5 hours of MSR, the 3% Pd/ZnO-300 H2 catalyst achieves a hydrogen production rate of 1628.0 mmol·gcat−1·h−1, with methanol conversion stabilized at 94%, CO2 selectivity reaching 97.7%, and CO content as low as 0.5%. These results outperform recent studies on hydrogen production. Furthermore, DFT calculations elucidate the complete reaction pathway (111) on PdZn. This study provides initial insights into the influence of metal-carrier interaction on the formation of PdZn alloy, suggesting a new direction for palladium-based catalysts in methanol steam reforming.

Catalytic Performances of Ni-containing Mesoporous TUD-1 Catalysts in Steam Reforming of Acetic Acid

Catalytic Performances of Ni-containing Mesoporous TUD-1 Catalysts in Steam Reforming of Acetic Acid

Enhancing Bio-Ethanol conversion to renewable H2 via Ethanol Steam Reforming over a highly porous “one-pot” nickel and molybdenum carbide-based catalyst

The pursuit of an economical, active, and stable catalyst for Bio-Ethanol Steam Reforming (ESR) to facilitate renewable H2 production continues. Especially considering that traditional-noble-metal-based catalysts, are too expensive for large scale applications. In this paper, a sol-gel Ni–Mo2C–Al2O3 catalyst was employed for the first time in the ESR reaction. Synthesized by an innovative “one-pot” sol-gel method, this highly porous catalyst (670 m2. gcat−1) promises to deliver, in a single material, the nickel's ability on cleaving C–C bonds with the known catalytic stability of Mo2C in reforming reactions. Catalytic stability and activity were tested over a wide range of temperatures (450 °C-700 °C) and at a high Gas-Hourly-Space-Velocity (GHSV), 200,000 mmol h−1. gcat−1. The high temperature tests (T > 650 °C) exhibited elevated stability (over 12 h) and activity (ethanol conversion and H2-Production-Rate of 100 % and 1700 mmol h−1. gcat−1, respectively). Besides, TPO-O2 and TEM micrographs have shown the presence of both graphitic and aromatic coke on tests E and H spent catalysts, 2.08 mgcarbon. gcat− 1h−1 and 541 mgcarbon. gcat− 1h−1, respectively. Nevertheless, given its more graphitic nature and lower formation rate, H2 yield, and conversion remained constant throughout the entirety of the high-temperature tests, confirming that the coke did not block the catalytic sites.

An Exsolved Cu Nanocatalyst for Highly Efficient Methanol Steam Reforming

AbstractBaZr0.1Ce0.7Y0.2O3 (BZCY) perovskite with in‐situ exsolved metallic Cu catalyst acted as a catalyst for methanol steam reforming (MSR) for the first time. After reduction at 550 °C for 3 hours, fine and uniform metallic Cu nanoparticles were exsolved from the perovskite lattice with more active sites and oxygen vacancies on the surface. The reduced Ba0.9Zr0.1Ce0.7Y0.1Cu0.1O3 (BZCYCu) displayed a stable conversion of methanol above 99.9 % at 500 °C within 120 hours, with a negligible amount of CO in the outlet gas and no carbon species was detected on the surface of catalyst. The BZCYCu gained 7.4 % of their weight at 500 °C during the water vapor adsorption stage in temperature programmed water absorption experiment, which showed a considerable water adsorption capacity. Such a hygroscopicity could promote the catalytic methanol steam reforming and CO elimination. And metallic Cu has also been widely applied for the methanol steam reforming reaction due to their high activity and carbon resistance. The synergy of metallic Cu nanoparticles and perovskite substrate with more oxygen vacancies and well hydroscopicity improved the structural stability and ensured the catalytic activity of RBZCYCu catalysts.

Interface engineering of Ce/La-doped hydrochar-supported nickel catalysts for enhanced tar reforming performance at low temperature

Catalytic reforming of biomass tar to syngas-especially under mild temperature-is an attractive albeit elusive route, necessitating the manufacture of highly efficient catalysts, in particular, from inexpensive, sustainable, and renewable resources as a prerequisite. Two interface-engineering strategies, including one-pot hydrothermal carbonization (HTC) approach and two-step HTC-impregnation method, were applied to fabricate a series of Ce/La-doped hydrochar-supported nickel catalysts, employing pinewood sawdust-derived hydrochar as the support, nickel as the active sites, and Ce or La as the promoter species. After the optimization of synthetic variables and operation conditions, the Ni0.1/Ce0.05-HC catalysts prepared by the two-step HTC-impregnation method simultaneously exhibited boosted activity, selectivity and recyclability than the Ni/HC counterpart without Ce addition as well as reported state-of-the-art catalysts in steam reforming of biomass tar at a low temperature of 600 °C. This exceptional catalytic performance was mainly attributed to the modulation of geometric structure and electronic structure of the exposed active sites by appropriate inclusion of cerium on the hydrochar-based nickel catalyst, which favored the water-gas shift, boudouard reaction and coke gasification, thereby imparting the materials with remarkable resistance against metal sintering and coke deposition during the steam reforming process. The result in this work underscores that the controlled interface between Ni species and hydrochar support by addition of Ce, which pertain to the hydrothermal processing technique, is a promising blueprint toward effective fuel production from waste biomass.

Influence of Ru-substitution on the performance of pyrochlore catalysts in oxidative steam reforming of ethanol

This study reveals that La2Zr2−xRuxO7−δ optimizes hydrogen production and ethanol conversion, particularly at a 2.66% Ru concentration, outperforming traditional 5 wt% Ru catalysts through superior long-term stability and efficiency.

Waste derived ash as catalysts for the pyrolysis-catalytic steam reforming of waste plastics for hydrogen-rich syngas production

Ash derived from the oxidation of waste tire and processed municipal solid waste in the form of refuse-derived fuel have been investigated for their potential as catalysts in the pyrolysis catalytic steam reforming of high-density polyethylene to produce hydrogen-rich syngas. The surface morphology, element distribution, pore structure and metal composition of the ashes were characterized to explore the effects of these ash properties on the catalytic process. Further work using tire ash investigated the influence of the process parameters, catalytic temperature and catalyst plastic ratio in relation to the production of hydrogen and syngas. The results showed that tire ash had a higher specific surface area and pore volume than refuse-derived fuel ash, resulting in a slightly higher hydrogen yield compared to refuse derived fuel ash. An increase in the temperature of the catalytic steam reforming process with the tire ash catalyst significantly increased the hydrogen yield from 13.3 mmol g−1plastic at 800 °C to 83.2 mmol g−1plastic at 1000 °C. At higher catalyst:plastic ratios, the higher amounts of catalyst produced no discernable increase in hydrogen. A tentative reaction mechanism in relation to waste derived ash as catalysts for the steam reforming of plastics pyrolysis volatiles is provided.

Long-term evaluation of palm oil mill effluent (POME) steam reforming over lanthanum-based perovskite oxides

To replace the obsolete ponding system, palm oil mill effluent (POME) steam reforming (SR) over net-acidic LaNiO3 and net-basic LaCoO3 were proposed as the POME primary treatments, with promising H2-rich syngas production. Herein, the long-term evaluation of POME SR was scrutinized with both catalysts under the optimal conditions (600 °C, 0.09 mL POME/min, 0.3 g catalyst, & 74–105 μm catalyst particle size) to examine the catalyst microstructure changes, transient process stability, and final effluent evaluation. Extensive characterization proved the (i) adsorption of POME vapour on catalysts before SR, (ii) deposition of carbon and minerals on spent SR catalysts, and (iii) dominance of coking deactivation over sintering deactivation at 600 °C. Despite its longer run, spent LaCoO3 (50.54 wt%) had similar carbon deposition with spent LaNiO3 (50.44 wt%), concurring with its excellent coke resistance. Spent LaCoO3 (6.12 wt%; large protruding crystals) suffered a harsher mineral deposition than spent LaNiO3 (3.71 wt%; thin film coating), confirming that lower reactivity increased residence time of reactants. Transient syngas evolution of both SR catalysts was relatively steady up to 4 h but perturbed by coking deactivation thereafter. La2O2CO3 acted as an intermediate species that hastened the coke removal via reverse Boudouard reaction upon its decarbonation. La2O2CO3 decarbonation occurred continuously in LaCoO3 system but intermittently in LaNiO3 system. LaNiO3 system only lasted for 13 h as its compact ash blocked the gas flow. LaCoO3 system lasted longer (17 h) with its porous ash, but it eventually failed because KCl crystallites blocked its active sites. Relatively, LaCoO3 system offered greater net H2 production (72.78%) and POME treatment volume (30.77%) than LaNiO3 system. SR could attain appreciable POME degradation (>97% COD, BOD5, TSS, & colour intensity). Withal, SR-treated POME should be polished to further reduce its incompliant COD and BOD5.

Modulation of Rh species in Rh/Al2O3/FeCrAl-foam structured catalysts for steam reforming of toluene

Steam reforming of tar is an appealing way for tar elimination during biomass gasification. In this work, structured Rh/Al2O3 supported on FeCrAl-foam catalysts with different Rh species contents (Rh0, RhiOx and Rh(AlO2)y) were modulated through calcination and/or reduction at different temperatures for toluene steam reforming. Among all the structured catalysts and conventional supported catalysts, the structured Rh/Al2O3/FeCrAl-foam catalyst, calcined in air at 300 °C followed by reduction with hydrogen at 600 °C, showed superior activity as well as excellent resistance to sintering and coke deposition. Such high performance can be attributed to the suitable Rh0/RhiOx ratio as well as the enhanced mass transfer capability. The integrated studies of controlled catalytic tests, catalyst characterizations, TPSR, H2O-TPD and in-situ DRIFTS revealed that metallic Rh0 site was responsible for the cleavage of the C-C/C-H bonds in toluene. The activate ability of H2O was governed by the Rh0/RhiOx ratio, while the RhiOx specie played a significant role, which further promotes the reaction activity and eliminate coke deposition. Furthermore, the RhiOx specie enable the catalyst with high sintering resistance, due to the strong affinity to the Al2O3 surface. However, the Rh(AlO2)y specie was inactive. The catalytic performance was controlled by balancing the toluene activation and H2O dissociation. Consequently, rational tuning of these species is crucial for obtaining high-performance Rh/Al2O3 catalysts for steam reforming of toluene.

Machine learning-driven optimization of Ni-based catalysts for catalytic steam reforming of biomass tar

Biomass gasification is a promising process for producing syngas, which is widely used in various industrial processes. However, the presence of tar in syngas poses a significant challenge to biomass gasification due to the difficulties in its removal and potential downstream issues, such as clogging, slagging, and corrosion. Extensive efforts have been made to address this challenge through catalytic tar removal using various catalysts, generating a vast amount of experimental data. Processing this large dataset and gaining new insights into process optimization requires the development of efficient data analysis methods. In this study, a comprehensive database was built, encompassing a total of 584 data points and 14 input parameters collected from literature published between 2005 and 2020. Machine learning algorithms were then trained using this dataset to predict and optimize the catalytic steam reforming of biomass tar. The predicted results were found to agree well with the experimental data. The results show that the reaction temperature is the most important process parameter, with the highest relative importance of 0.24, followed by the support (0.16), additive (0.12), nickel (Ni) loading (0.08), and calcination temperature (0.07), among the 14 input parameters. This work has proposed optimal ranges for the reaction temperature (600–700 °C), Ni loading (5–15 wt%), and calcination temperature (500–650 °C). Furthermore, it was found that a larger specific surface area and higher Ni dispersion are two critical factors for selecting additives and supports. This study provides insights into key parameters for optimizing the catalytic steam reforming of biomass tar, enabling enhanced efficiency and effectiveness in biomass gasification processes.

Cu-promoted Ni-LaCeOx/SBA-15 catalysts for ethanol steam reforming

Hydrogen is a globally recognized high-energy, clean, and ecofriendly fuel that is currently produced by means of electrocatalysis, biomass conversion, coal gasification, and thermal decomposition of hydrocarbons, with the steam reforming showing high potential. The present work is focused on Cu-promoted SBA-15-supported Ni-LaCeOx catalysts for ethanol steam reforming (ESR). The catalysts were prepared by incipient wetness impregnation and characterized by XRF, N2 adsorption-desorption, IR spectroscopy, SAXS, XRD, H2-TPR, Raman, and STA methods. The support features caused by the distribution of LaCeOx NPs and Cu promoter in proper ratios affect the conditions of formation of active dispersed Ni species to determine the catalyst performance and its reducibility. At 800 оС, the NiСu-LaCeOx/SBA-15 (1:1) catalyst demonstrates a 100 % ethanol conversion and 55 % hydrogen yield. Thus, the role of the Cu-containing promoter comprises both a significant decrease of carbon deposits on the catalyst surface and redirecting of the intermediate interactions towards the formation of the desired gaseous products.

Influence of Rh addition to transition metal-based catalysts in the oxidative steam reforming of acetic acid

In this work, the Rh-promotion to transition metal (Ni and Co) CeO2-supported catalysts has been studied for the first time on the acetic acid oxidative steam reforming. Characterization of the prepared catalysts confirmed the promoting effect of rhodium addition, allowing lower crystallite size which increases the number of available active sites to reactants, along with higher reducibility as evidenced by temperature-programmed reduction (H2-TPR). The influence of the reaction temperature on the acetic acid conversion and hydrogen yield was assessed. Co-based catalysts achieved better catalytic performance than Ni-based samples, almost complete acetic acid conversion, and hydrogen yields were close to the equilibrium values at temperatures over 500 ºC. On the other hand, tests at higher weight-hour space velocity evidenced the superior activity of Co-Rh/CeO2 sample. This sample showed good stability with almost complete acetic acid conversion after 25 h time-on-stream, decreasing only the hydrogen yield by 7% after the first 8 h along with a slight increase in the acetone yield of about 6%. This suggests that after the acetic acid ketonization, acetone steam reforming advanced to a lesser extent on the reaction mechanism because of long-term slight catalyst deactivation.

Isolating the effect of Co and Ce on Ni–X–Y/Al2O3 bi- and trimetallic reforming catalysts for hydrogen generation

This work investigates the individual and combined promoting effects of ceria and cobalt on a nickel-based catalyst for steam reforming. First, the catalysts were synthesized using a fixed 20 wt% Ni content and variable Ce and Co, 0-10 wt% contents. We used a combined experimental (characterization and testing) and computational framework to assess the promoting role in catalytic activity and stability for nickel-alumina-based catalysts. The formation of Ni-Co alloy was approved by combining different characterization techniques. The Ni20Ce2Co10/Al catalyst exhibits superior conversion, H2 yield, and lifetime. The obtained catalytic activity is attributed to the presence of bare Co sites that reduces the Ni crystal size, enhances the accessibility of active sites, promotes the metal–support interaction, and facilitates C-C scission. In addition, the incorporation of Ce with low loading (2 wt %) to Ni-Co interface enhances the accessibility of oxygen vacancy, facilitates the reaction, prevents coke formation and maintains catalytic activity for prolonged lifetime. The simplicity and cost-effectiveness of this proposed catalyst make it an appealing option for scaling up.

A Fibrous Perovskite Nanomaterial with Exsolved Ni-Cu Metal Nanoparticles as an Effective Composite Catalyst for External Steam Reforming of Liquid Alcohols

The conversion of hydrogen to power via combined external reforming of liquid alcohol and solid oxide fuel cell (SOFC) technology is an effective approach to address future energy challenges. In this study, an La0.8Ba0.1Mn0.8Ni0.1Cu0.1O3 (LBMNCu) perovskite nanofiber with high porosity was synthesized with a modified electrostatic spinning method, which acted as an efficient catalyst for steam reforming of liquid alcohols (methanol and ethanol). After reduction, fine metallic Ni-Cu was uniformly distributed throughout the perovskite nanofiber surface. The obtained composite displayed a methanol conversion above 99.9% at 450 °C and an ethanol conversion above 99% at 600 °C, which was highly superior to the common Ni-Cu/Al2O3 catalyst. The catalytic performance of our assembled catalysts also remained stable in methanol and ethanol atmospheres for 50 h and no coking was detected. Furthermore, when the reformed gas was fed into a Y0.08Zr0.92O2 (YSZ)-based SOFC system, the open circuit voltage remained around 1.1 V at 700 °C for 50 h accordingly, without coking, and the voltage remained virtually unchanged at 0.7 V for 50 h at 700 °C and 400 mA cm−2 during galvanostatic discharge mode, indicating that using LBMNCu nanofiber as a catalyst for hydrogen production and utilization is an efficient strategy. The interaction of the in situ exsolved metallic nanoparticles and nanofibrous perovskite could also be a promising approach for designing a highly active catalyst for H2 generation.

Highly efficient steam reforming of biomass tar model compound using a high-entropy alloy-based structured catalyst

The development of efficient Ni-based catalysts for steam reforming of biomass tar is crucial for the widespread application of biomass gasification. Multimetal high-entropy alloys (HEAs) have emerged as promising catalysts that can potentially replace conventional metallic materials in various applications. In this study, we investigate NiFeCoMnCu-HEA catalysts supported on the surface of wood carbon (WC) for highly efficient steam reforming of toluene, a model compound for biomass tar. The synergistic effect between Ni and the other four metals in the HEA composition inhibits coke formation during the reaction process, while the appropriate mole ratio of Ni: (Fe + Co + Mn + Cu) reduces the particle size of HEA nanoparticles. Furthermore, the unique structure of wood carbon, with its long, interconnected, yet distorted microchannels, enhances the dispersion of active sites and improves mass transfer efficiency. As a result, the NiFeCoMnCu-HEAs/WC catalyst exhibits outstanding catalytic activity, achieving over 95% toluene conversion for 48 h at 650 °C. This performance surpasses that of the compared catalysts prepared in this work, namely NiFeCoMn/WC (39%), NiFeCoCu/WC (31%), and NiFeCo/WC (20%), underscoring the significance of the HEA structure. The findings also offer valuable insights into enhancing the performance of other nanostructures in the steam reforming of biomass tar.