Catalysts For Steam Reforming Research Articles

Impact of Potassium Addition on the Performance of Ni/MgAl2O4 Catalysts in Steam Reforming of Bio-Oil Model Compounds

Impact of Potassium Addition on the Performance of Ni/MgAl₂O₄ Catalysts in Steam Reforming of Bio-Oil Model Compounds

Steam reforming of toluene as model compounds of biomass tar by Fe–K-based biochar nano-catalysts at mild temperatures

Development of efficient catalysts for steam reforming of biomass tar is crucial for the widespread application of biomass gasification. In this work, a novel biochar nano-catalyst (BN) is conveniently prepared via one-step catalytic pyrolysis, using K and Fe to adjust the surface structure of the biochar, thereby enhancing the activity for toluene reforming. Fe–K/BN is tested in a fixed-bed reactor for steam reforming of toluene, a model compound of biomass tar, achieving a 100% toluene conversion rate at 650 °C. Fe–K/BN is activated in situ with steam to increase their specific surface area and enhance the O-containing functional groups on the surface, improving toluene adsorption and reforming. Finally, the stability of Fe–K/BN is tested in the simulated syngas, maintaining a 100% toluene conversion rate during a 26-h continuous catalytic reforming experiment. This work provides a promising strategy for the design of an active and stable catalyst for toluene reforming, which has potential for application of tar steam reforming during biomass gasification.

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.

Steam reforming of dodecane using Ni-red mud catalyst: A sustainable approach for hydrogen production

Conventional energy sources emit huge amounts of carbon dioxide (CO2) into the atmosphere causing global warming. Hydrogen (H2) is an alternative clean energy carrier that produces only heat and water vapor upon combustion. In this work, we utilized industrial waste material (Red Mud, RM) to develop a cost-effective and efficient catalyst for steam reforming of diesel (n-dodecane as a model compound) for hydrogen production. We impregnated nickel (Ni), a prudent and effective metal, in red mud (RM) in varied proportions to employ as a catalyst for hydrogen production. The catalysts' structure was characterized by powdered X-ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Electron Dispersive Spectroscopy (EDS) were used to measure the elemental composition while Scanning Electron Microscopy (SEM) was used to investigate the catalysts’ morphology. Surface area and porosity were analyzed using the N2 adsorption/desorption isotherms, and H2-Temperature Programmed Reduction (H2-TPR) to study the reducibility and interaction of Ni species to the RM. The catalysts were then evaluated for hydrogen production by the steam reforming process of n-dodecane (SRD). It was found that the catalyst with 20% Ni loading (20% Ni@RM) can produce hydrogen with selectivity as high as 75%, and stability for 20 h with a negligible decline in the catalyst performance.

Cu0·1In0·01/S-1 catalysts with high efficiency towards methanol steam reforming

Cu0·1/S-1, Cu0·1Zn0·01/S-1, Cu0.1Inx/S-1 (x = 0.01, 0.03, 0.05) and Cu0·1Ce0·01/S-1 were successfully prepared with S-1 as the carrier material and applied to methanol steam reforming (MSR) reaction. To further explore its chemical and physical properties, XRD, BET, SEM-EDS, ICP, FTIR, H2-TPR, NH3-TPD, CO2-TPD, and Raman were used to characterize the synthetic S-1 zeolite catalysts. The measured physicochemical properties revealed that utilizing S-1 zeolite as the carrier effectively altered the size of the metal particles, enhancing their dispersion and reduction characteristics. Compared with five different types of S-1 zeolite catalysts, the Cu0·1In0·01/S-1 catalyst has a large specific surface area and pore size. It exhibited superior active metal dispersion, with the lowest reduction temperature for the active metal CuO. The catalyst also showed a high Lewis acid content on its surface, forming the In-Lewis acid site. Consequently, the Cu0·1In0·01/S-1 catalyst exhibits exceptional performance in methanol steam reforming for hydrogen production reactions. It exhibited the best performance with a methanol conversion rate of 100%, H2 selectivity of 100% under the conditions of 1 MPa, 250 °C, the S/C molar ratio of 2.5, and the WHSV of 0.5 h−1, which outperforms most of the reported catalysts in methanol steam reforming.© 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Novel Ni–Ru/CeO2 catalysts for low-temperature steam reforming of methane

Upgrading of biogas and biomethane into H2-rich streams by steam reforming is regarded as an effective strategy to reduce fossil fuel consumption contributing to the transition towards a green energy system. In this context, novel reactor configurations such as membrane reactors appear a promising route for process intensification, but they require novel catalysts more active at low temperatures, stable, and resistant to coke formation. In this work, we prepared and tested structured catalysts characterized by a low Ni content (7 wt%) and a very low Ru content (≤1 wt%) supported on ceria and deposed onto SiC monoliths. Catalysts were tested at low temperatures (<600 °C), i.e. at temperatures suitable for applications in Pd-based membrane reactors. Fresh and used catalysts were characterized by ICP-MS, N2 physisorption, XRD, TEM, SEM-EDS, XPS and H2-TPR to identify the physicochemical properties affecting the catalytic activity. The catalysts showed good activity towards methane reforming, stable performance, and good resistance to coke formation. Ruthenium affects both the intrinsic catalytic activity and the resistance to the inhibiting effect of steam on the reaction rate. This is related to improved redox properties due to the intimacy between the active metals and their strong-metal-support-interaction with the ceria. Finally, our catalysts show self-activation under reaction conditions, which is an interesting property for applications.

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 are 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. Moreover, the review investigates the causes of deactivation in Ni-based catalysts during MSR reactions and proposes strategies for extending catalyst lifespan through fine design and optimization of operation parameters. Lastly, this review outlines the current research challenges and anticipates the future trends and potential applications of Ni-based catalysts in MSR hydrogen production. By offering a comprehensive critical analysis, this review serves as a valuable reference to enhance MSR hydrogen production efficiency and catalyst performance.

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.

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.