Steam Reforming Of Tar Research Articles

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.

Microwave driven steam reforming of biomass model tar based on metal organic frameworks (ZIF-67) derived Co/C catalyst

Tar catalytic removal is a key issue in biomass gasification, which is suffering from catalyst coking and sintering. Microwave technology is attractive due to the high activity on polar molecules and ability to lower activation energy. In this study, the Co/C derived from metal-organic frameworks (ZIF-67) was developed as a bifunctional microwave catalyst that can strengthen the interaction between microwave and tar catalytic reforming, and enhance the anti-coking and sintering ability. The effects of the temperature, heating method, tar concentration, and catalyst support on model tar conversion rate were investigated. The operating conditions at 700 °C and tar concentration lower than 20 g/m3 can reach a promising conversion rate over 90.15 % under microwave irradiation. On the one hand, microwave heating groups performed better in conversion rate and coking compared to conventional heating, due to the active species generated from the microwave plasma. On the other hand, Co/C showed better performance in catalytic activity and sintering stability, due to the highly dispersion of cobalt nanoparticles and the confinement effect of carbon nanotubes on the catalyst surface. These findings proposed a novel approach for efficient biomass tar removal under microwave irradiation, and offered a potential tool to further reveal the mechanism in microwave driven tar steam reforming system.

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.

Optimization and Techno-Economic analysis of catalytic gasification of wheat straw biomass using ASPEN PLUS model

Biomass gasification efficiently produces heat, electricity, and power. However, removing harmful contaminants from raw syngas is crucial. Tar production is a challenge due to blockage, plugging, and corrosion. Tar steam reforming (TSR) is the most promising technique, converting high molecular weight hydrocarbons into CO, CO2, H2, and CH4. In this study, a model of biomass gasification using wheat straw as biomass feedstock has been developed using Aspen Plus. The gasification flow sheet encompasses gasification, catalytic filter candle, gas cleaning, impurity removal reactor, separator, and subsequent sorbent reactors. Ni-based catalysts with Ni ratios (5%, 10%, and 15%) are used to simulate TSR reactions. Results show that the 15% Ni-Co-Al2O3 catalyst outperforms the 10% and 5% Ni-Co-Al2O3 catalysts. This study explores the impact of temperature, catalyst loadings, and steam-to-carbon (S/C) ratios on toluene conversion and hydrogen yield in catalytic steam reforming, along with temperature, steam-to-biomass ratios, and equivalence ratio on syngas fraction in gasification. It includes a techno-economic analysis of wheat straw gasification to improve syngas energy through efficient tar conversion.

Highly Efficient Transformation of Tar Model Compounds into Hydrogen by a Ni-Co Alloy Nanocatalyst During Tar Steam Reforming.

Hydrogen (H2) production from coal and biomass gasification was considered a long-term and viable way to solve energy crises and global warming. Tar, generated as a hazardous byproduct, limited its large-scale applications by clogging and corroding gasification equipment. Although catalytic steam reforming technology was used to convert tar into H2, catalyst deactivation restricted its applicability. A novel nanocatalyst was first synthesized by the modified sol-gel method using activated biochar as the support, nickel (Ni) as the active component, and cobalt (Co) as the promoter for converting tar into H2. The results indicated that a high H2 yield of 263.84 g H2/kg TMCs (Tar Model Compounds) and TMC conversion of almost 100% were obtained over 6% Ni-4% Co/char, with more than 30% increase in hydrogen yield compared to traditional catalysts. Moreover, 6% Ni-4% Co/char exhibited excellent resistance to carbon deposition by removing the nucleation sites for graphite formation, forming stable Ni-Co alloy, and promoting the char gasification reaction; resistance to oxidation deactivation due to the high oxygen affinity of Co and reduction of the oxidized nickel by H2 and CO; resistance to sintering deactivation by strengthened interaction between Ni and Co, high specific surface area (920.61 m2/g), and high dispersion (7.3%) of Ni nanoparticles. This work provided a novel nanocatalyst with significant potential for long-term practical applications in the in situ conversion of tar into H2 during steam reforming.

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.

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.

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.

The Efficiency of Carbon Conversion and Hydrogen Production from Tar Steam Reforming of Biomass Using Ni-Based Catalysts with Alkaline Earth Promoters

H2 production can be used as a clean and renewable energy source for various applications, including fuel cells, internal combustion engines, and chemical production. Using nickel-based catalysts for steam reforming biomass tar presents challenges related to catalyst deactivation, poisoning, heterogeneous composition, high process temperatures, and gas impurities. To overcome these challenges, adopting a nickel-based catalyst with selected oxide support and MgO and CaO promoter is a promising approach for improving the efficiency and sustainability of steam reforming for hydrogen production. The majority of studies conducted to date have focused on the steam reforming of particular tar compounds, most commonly benzene, phenol, toluene, or naphthalene, over a range of support catalysts. However, the actual biomass tar composition is complex, and each component impacts how well steam reforming works. In this research, a multi-compound biomass tar model including phenol, toluene, naphthalene, and pyrene underwent a steam reforming process. Various types with 10 wt.% of nickel-based catalysts were generated by the co-impregnation technique, which included 90 wt.% different oxide supports (Al2O3, La2O3, and ZrO2) and 10 wt.% of combination alkaline oxide earth promoters (MgO and CaO). Thermogravimetric analysis, Brunauer–Emmett–Teller (BET) method, N2 physisorption, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (CO2-TPD), and X-ray diffraction (XRD) of ni-based catalyst characterized physiochemical properties of the prepared catalyst. The reaction temperature used for steam reforming was 800 °C, an S/C ratio of 1, and a GHSV of 13,500 h−1. Ni/La2O3/MgO/CaO (NiLaMgCa) produced the most carbon to-gas conversion (86.27 mol%) and H2 yield (51.58 mol%) after 5 h of reaction compared to other catalysts tested in this study. Additionally, the filamentous carbon coke deposited on the spent catalyst of NiLaMgCa does not impact the catalyst activity. NiLaMgCa was the best catalyst compared to other catalysts investigated, exhibiting a stable and high catalytic performance in the steam reforming of gasified biomass tar. In conclusion, this study presents a novel approach by adding a combination of MgO and CaO promoters to a ni-based catalyst with various oxide supports, strengthening the metal-support interaction and improving the acid-base balance of the catalyst surface. The mesoporous structure and active phase (metallic Ni) were successfully developed. This can lead to an increase in the conversion of tar to H2 yield gas and a decrease in the production of undesired byproducts, such as CH4 and CO.

Comparison of reaction characteristics and kinetics between tar thermal cracking and steam reforming in a micro fluidized bed reaction analyzer

In this study, a micro fluidized bed reaction analyzer (MFBRA) was used to investigate the reaction characteristics of tar thermal cracking and steam reforming at different temperatures (T, 750, 850, and 950 °C) and steam partial pressures (SP, 10%, 20%, and 30%). The reaction kinetics, including gas components generation (H2, CO, CO2, and CH4) and carbon (C) conversion in gas products, were calculated and further compared. For the two processes, the behaviors of gas generation and C conversion can be classified as Stage-1 and Stage-2 based on the different increases. By raising temperature and SP, the yields of H2/CO/CH4 and C conversion increased obviously, while CO2 showed a growing and subsequently declining trend. A similar phenomenon also existed in the relationship between reaction rate Vs. gas yield/C conversion. Compared to thermal cracking, the reaction time in tar steam reforming became much longer; the yields of H2/CO/CH4 and the C conversion increased significantly, while CO2 decreased. In the meantime, there was a clear reduction in all reaction rates of gas generation and C conversion. Furthermore, in tar steam reforming, the activated energy (Ea) of gas components generation (H2, CO, CO2, and CH4) decreased from 114.92 to 90.48, 86.54–74.49, 32.39–28.87, and 55.34–42.06 kJ/mol, respectively; and Ea of total C conversion lowered from 87.74 to 65.75 kJ/mol. Additionally, SP had no impact on Ea during tar steam reforming. To ensure the validity of the test results by MFBRA, the kinetics of tar thermal cracking was compared with that in the literature.

Facile synthesis of low-cost Co-Cu/C alloy catalysts for hydrogen-rich syngas production from low-temperature steam reforming of biomass tar

Recovering beneficial metal ions from industrial effluents by suitable support can be an efficient and environment-friendly way to prepare specific catalysts directly. Herein, modified lignite was developed as an ion exchange material and used to prepare Co-Cu bimetallic catalysts for hydrogen-rich syngas production from steam reforming reactions. For all the catalysts studied, Co75Cu15/600 (carbonization temperature at 600 °C) exhibits the optimal catalytic activity and stability in both steam reforming of toluene and biomass tar under low temperatures. Fresh and spent catalysts were detailedly characterized to investigate the metal interactions and catalyst deactivation. The introduction of Cu contributes to the formation of Co-Cu alloy and the lower particle size of Co (4.17 nm), thereby suppressing the carbon deposition, the oxidation of metals and the change of catalyst structure after reaction. Therefore, the inexpensive and readily-available Co-Cu/C has the potential to serve as a promising catalyst for large-scale biomass gasification technology.

Preparation of highly dispersed lignite-char-supported cobalt catalyst for stably steam reforming of biomass tar at low temperature

The removal of generated tar during the biomass gasification is a serious issue. Catalytic tar cracking is one of the most efficient methods to reduce tar deposition while many common tar cracking catalysts suffer problems of serious carbon deposition and active metal sintering, especially at low temperatures. Therefore, developing catalysts with both high activity and stability is critical. In this work, we aim to prepare catalysts with a high active metal contents, a small metal particle size and a high dispersion to contribute to the highly efficient tar removal at relatively low temperatures. By adjusting the type and the concentration of the Co precursor solution when lignite is used as the carbon precursor, we prepared a series of catalysts which were then applied for both activity and stability test of the steam reforming of model tar and biomass tar. The results show that Co0.15-C2H3O2− prepared with a 0.15 M solution of Co(C2H3O2)2·4H2O achieves a Co content of about 16.0 wt% with an average particle size of about 3.77 nm and a relatively high metallic Co dispersion. For steam reforming of toluene, the catalyst achieves an almost 100 % toluene conversion at 400 °C and exhibits a high stability in the 100 h test. Moreover, Co0.15-C2H3O2−, which produces approximately 283.8 mL.gcorncob−1.gcat−1.h−1 H2 catalytically, is also active and stable in biomass tar cracking. The catalyst prepared in the present study by using the economic and simple ion-exchange method also has a well-dispersed nano-metal-loaded structure and can efficiently remove the tar at a low temperature with a high stability, which will contribute to the industrial application in the future.

Hydrogen production from tar steam reforming over hydrangea-like Co-phyllosilicate catalyst derived from Co/Sepiolite

Co-phyllosilicate with structure flexibility is acknowledged as a promising catalyst for hydrogen production by steam reforming. In this work, a series of hydrangea-like Co-phyllosilicate catalysts were synthesized by a template-free urea hydrothermal method, where the silica source was supplied by amorphous sepiolite. Both the exsolution property of phyllosilicate and the hierarchical macro-/meso-pore architectures of hydrangea-like morphology were combined to improve the metal dispersion and reactant activation. The catalytic behaviors of as-synthesized xCo/SEP-PS catalysts were evaluated in simulated tar (phenol + ethanol) steam reforming. It was founded that 10Co/SEP-PS catalyst achieved an optimal conversion (89.3%) and H2 yield (67.4%) at 700 °C, as well as the lowest apparent activation energy of 35.5 kJ/mol. Various characterization results coupling with experimental investigations indicated that the fine Co particles implanted on Co-phyllosilicate lamella were highly stable and active for H2 production. Meanwhile, the hydrangea-like Co-phyllosilicate provided high Lewis acidity and developed pore structure, significantly facilitating the reactant adsorption and activation, especially for phenol dehydrogenation. The synergy between developed pore structure and enhanced metal-support interaction of Co-phyllosilicate conferred 10Co/SEP-PS with a robust durability in a 50 h stability test and effective resistance to metal sintering and coke deposition.

How syngas composition affects catalytic steam reforming of tars: An analysis using toluene as model compound

Tar removal by catalytic steam reforming has an important role to play in gasification hot gas treatment. Despite the importance of understanding the influence gas atmosphere has on this reaction, the effect of a full syngas mixture has not been comprehensively investigated. This study aims to bridge that gap by analyzing the effect of each component as well as their combinations on steam reforming of toluene as biomass gasification tar model over a Ni/Al2O3 catalyst. It has been found that H2, CO and CO2 have minor inhibitory effects, slightly decreasing the initial toluene conversion. On the other hand, while CO and CO2 do not lead to catalyst deactivation, H2 and CH4 deactivate Ni/Al2O3 by promoting coke deposition. Only 3 vol.% of CH4 can significantly increase deactivation, despite being insignificant with toluene or CH4 separately. The joint presence of CH4 and H2 causes further drops in conversion with time on stream.

Modulating lattice oxygen activity of Ca2Fe2O5 brownmillerite for the co-production of syngas and high purity hydrogen via chemical looping steam reforming of toluene

The chemical looping steam reforming (CLSR) of biomass tar enables the process intensification for the co-preparation of syngas and high purity hydrogen. The practical application of brownmillerite-structured Ca2Fe2O5 is hindered by activity-related issues such as low fuel conversion and oxygen transfer capacity. Here, the doping of heteroatoms, e.g. Ni induces structural changes to the brownmillerite lattice, transforming it from a Pnma phase to a Pcmn one, with increased distortion of the FeO6 octahedra. The structural changes lead to the upwards shifts of the O 2p band of oxygen carrier, and subsequently improved lattice oxygen activity as well as oxygen transfer capacity. The formation of oxygen vacancy is a rate determining step during CLSR, while the Ni-doped Ca2Fe2O5 reduces the energy of oxygen vacancy formation and energy barrier for lattice oxygen migration through the bulk. During CLSR, Ca2Ni0.25Fe1.75O5 lead to significant improvement in syngas productivity, hydrogen purity and fuel conversion.

Construction of high-performance NiCe-MOF derived structured catalyst for steam reforming of biomass tar model compound

High-performance and inexpensive catalysts play a large role in effective removal of biomass tar produced during biomass gasification. In this study, raw wood, with long, through, but distorted channels and a low tortuosity, was selected as a support. A layered NiCe-metal organic framework (NiCe-MOF) was grown in-situ on the surface of raw wood microchannels by using abundant surface hydroxide groups. Then, this catalyst was carbonized at 600 °C in a N2 atmosphere to obtain NiCe-MOF derived catalyst/wood carbon (NiCe-MDC/WC), which was selected as a structured reactor for the steam reforming of biomass tar. NiCe-MDC/WC achieved an excellent conversion rate of approximately 99% for toluene and a high catalytic stability of 48 h at low temperature of 550 °C. Moreover, NiCe-MDC/WC showed higher catalytic performance than Ni-MDC/WC (∼79%), crushed-NiCe-MDC/WC (∼94%), and Ni/WC (∼75%) in stability tests. These excellent results were assumed to be derived from the multilevel structure obtained from wood carbon microchannels and secondary layered MOF channels, appropriate metal-support interactions, and the presence of Ce, which could improve the dispersion of active sites and mass transfer efficiency and inhibit coke formation. Thus, such Ni-based MOF-derived structured reactors are promising for tar conversion and useful syngas production.

Effect of Ni-Co bimetallic core-shell catalyst for coke resistance in CO2 reforming of biomass Tar

The deactivation of catalysts due to coke deposition is a major challenge in CO2 reforming of tar technology. The Ni-Co bimetallic catalysts have good resistance to coke deposition for steam reforming of tar, but the performance of for filamentous coking of CO2 reforming of tar is not known. In this work, the effect of Ni-Co bimetallic synergy on the corrosion resistance of filamentous coke was investigated by comparing the catalytic performance of nickel monometallic and Ni-Co bimetallic core-shell catalysts. The Ni8Co@SiO2 catalyst showed efficient and stable hydrogen conversion (62.3–53.3%) and carbon conversion (64.7–56.7%) and excellent resistance to coke deposition with little coke (1.5%) deposition after 300 min of CO2 reforming tar reaction. The Ni8Co@SiO2 was also regenerated for four cycles, demonstrating excellent catalytic activity and recyclability performance. However, as the cobalt content in the Ni-Co bimetal increased, the activity and resistance to coke deposition of the core-shell catalyst decreased due to the increase in size of the Ni-Co alloy and the decrease in the nickel active component. The above results are helpful for the future application of bimetallic core-shell catalyst during CO2 reforming tar.

Oxygen-rich ultramicroporous activated carbon for boosting H2 production via toluene steam reforming: Effect of H2O2-modification and Ni/Co loading

The development of sustainable materials to produce a highly stable and efficient tar removal catalyst is important for biomass gasification technology. In this study, the effect of support modification using hydrogen peroxide (H2O2) and Ni and/or Co loadings on catalytic performance over palm kernel shell-based activated carbon (AC) supported catalysts for hydrogen (H2) production via steam reforming of toluene as biomass tar model compound have been investigated. The H2O2-modified AC (ACP) registers enhanced surface oxygenated functional groups and ultramicroporosity leading to highly dispersed active metals sites with uniform distribution and high acidity after NiCo impregnation. The highest activity is conferred by 10%Ni-10%Co/ACP at 93.8% and 90.2% of H2 yield and toluene conversion, respectively, with 325 h of stability. This is attributed to high turnover frequency, small crystallite size, weak metal-support interaction (WMSI) and simultaneous NiCo reducibility. The WMSI leads to carbon nanotube formation with tip-growth mechanism and suppresses catalyst deactivation. The reaction is endothermic and non-spontaneous with an ordered system at transition state. The results imply that the oxygenated functionalized ultramicroporous palm kernel shell-based ACP has a great potential as a high-performance catalyst in steam reforming of tar for H2 production.

Ni-Fe-Ce hydrotalcite-derived structured reactor as catalyst for efficient steam reforming of toluene

Development of the efficient and inexpensive catalyst for steam reforming of biomass tar plays a significant role in the wide application of biomass gasification. In the present study, the long, through, but distorted channels with a low tortuosity of wood, which are preserved after carbonization and the Ni-Fe-Ce hydrotalcite-derived catalyst deposition, were employed for the catalytic steam reforming of biomass tar. Outstanding catalytic activity was achieved as the reactant gases flow through the Ni-Fe-Ce hydrotalcite-derived structured reactor (NiFeCe-HTc/WC), with over 98.5% toluene conversion and good stability observed at 550 °C. Moreover, the NiFeCe-HTc/WC catalyst exhibited much better catalytic performance compared to the NiFe-HTc/WC catalyst and the Ni-Fe-Ce hydrotalcite-derived catalyst supported on traditional activated carbon (NiFeCe-HTc/AC). This was because of the presence of Ce, the open but distorted channels of monolithic wood, and the graphitic carbon layer covering the active sites, which could improve the dispersion of Ni species and the mass transfer efficiency, and prevent coke formation. This work demonstrated that the Ni-Fe-Ce hydrotalcite-derived structured reactor is potentially cost-effective for a range of high-temperature applications.

Upgrading syngas from wood gasification through steam reforming of tars over highly active Ni-perovskite catalysts at relatively low temperature

Tar formation during biomass gasification causes several operational problems, besides limiting the downstream application of the syngas produced. The development of an efficient catalyst for tar reforming at mild temperature is targeted. In this study, La-based perovskite (La0.6Sr0.4Co0.2Fe0.8O3-δ)-supported Ni materials have been synthesized through wetness impregnation (Ni/LSCF) and one-pot sol-gel method (Ni-LSCF). As-prepared catalysts have been characterized by N2 physisorption, XRD, TPR, H2-TPD and XPS. The impact of the synthesis path and the effect of Ru have been evaluated in steam reforming of toluene and phenol at low temperature (550 °C) under a model syngas. Regardless the tar model molecule, similar catalytic stability and activity toward tar reforming were attained for both Ni/LSCF and Ni-LSCF. However, a better catalytic performance toward WGS and higher resistance to coke formation were evidenced for Ni-LSCF than for Ni/LSCF. This better behavior has been mainly ascribed to the high Sr content at its surface, pointing out the key role of the basic elements at the catalytic surface in the activity and stability in steam reforming of tars. The addition of Ru led to an enhancement in the catalytic activity for toluene reforming, while no noticeable improvement was attained for phenol reforming.