Biomass Tar Model Compound Research Articles

Recent progress and perspectives of catalyst design and downstream integration in biomass tar reforming

In the last few decades, the development of biomass energy has become a key research focus to press the emissions of greenhouse gas. Syngas production from biomass tar reforming in the presence of the heterogeneous catalyst has been proved to be a clean and promising technology, which could be further connected to the downstream for fuel valorization. Up to now, some literatures has screened the reaction pressure, temperature, atmosphere, and heterogeneous catalyst in tar elimination during the biomass thermochemical conversion process. However, there are some problems, like the economical catalyst chosen for the industrial development of gasification, and integration difficulties between gasification and downstream technologies are still not well discussed. Hence, in this review, we first assess the recent advancements in catalyst fabrication and the activity performance in reforming biomass tar and tar model compounds. After that, the clean-up of produced gas for the next-step application is reviewed. Importantly, we discuss the composition of the produced gas, the possibilities and challenges of the integration with the production of methane, methanol, ethanol, and C2+ alcohols. Finally, the conclusion and prospective are concluded to give an outlook for the development of catalyst, biomass tar reforming, and integration with downstream technologies.

Experimental and thermodynamic study on sorption-enhanced steam reforming of toluene for H2 production using the mixture of Ni/perovskite-CaO

It is known that a considerable amount of tar is usually generated in the biomass gasification process, and catalytic steam reforming is an effective method to remove this by-product. The coupling of in-situ CO2 capture in the process can further shift the forward reforming reaction and produce hydrogen with a high purity. In this work, sorption enhanced steam reforming (SESR) of toluene (as a model compound of biomass tar) was investigated thermodynamically and experimentally using the mechanically mixed Ni/perovskite catalyst and CaO sorbent. It is verified that the appropriate temperature is 650 °C under stoichiometric reaction (S/C = 2), and around 75% average H2 yield with a maximum H2 purity over 95% could be obtained. Moreover, the cyclic SESR-regeneration and characterization including XRD, SEM/EDS, TEM and XPS were carried out, and it shows a stable catalytic performance and compatibility of the Ni/perovskite catalyst in the SESR process for high-purity hydrogen production.

Steam reforming of toluene as model compound of biomass tar over Ni–Co/La2O3 nano-catalysts: Synergy of Ni and Co

A series of LaNi1-xCoxO3 (x = 0, 0.2, 0.5, 0.8 and 1) perovskite catalysts were prepared successfully and applied for toluene steam reforming as a model tar molecule. The Ni–Co alloy formation in reduced LaNi1-xCoxO3 was confirmed by TPR, XRD and XPS. The strong interaction in LaNi0.8Co0.2O3 between Ni and Co produced highly dispersed and smaller metal (8–9 nm), higher reducibility and larger amounts of active sites as well as more abundant oxygen defects and higher surface/lattice oxygen mobility, confirmed by XRD, TEM, TPR, XPS and O2-TPD. Also, a higher electron density prevented Ni from oxidation and sintering; a more oxidized Co (Co3+) facilitated the dissociation of water and activation of CO2, thus removing the coke. At 600 °C, S/C = 3.4 and WHSV = 16.56 ml h−1 gcat−1, an equilibrium conversion was achieved initially and over 80% conversion after 24 h were obtained for LaNi0.8Co0.2O3 with a high H2 yield (81.8% at maximum) and 8.0 of H2/CO ratio. The graphitic/filamentous coke formation was alleviated and no metal sintering was presented after the reaction.

Catalytic hydrocracking reactions of tetralin as aromatic biomass tar model compound to benzene/toluene/xylenes (BTX) over zeolites under ambient pressure conditions

The gas phase selective hydrocracking process of tetralin (biomass tar model chemical compound) into benzene, toluene and xylenes (BTX) was carried out over the H-Beta, H-Mordenite, H-USY, H-Y, and H-ZSM-5 zeolite catalysts in a packed bed reactor under applied atmospheric pressure. To the best of our scientific knowledge, this performed work presents the first systematic investigation, focused on tetralin, cracking to BTX under ambient 1bar. The highest catalytic activity and carbon deposition resistance were established over the H-ZSM-5 (SiO2/Al2O3=30) with the selectivity to the BTX of 52.2mol.% in intermediates’ liquid phase, 88.7mol.% of total conversion yield after the 4h time on stream, 370°C and gas hourly space velocity (GHSV)=530h–1, and limited site deactivation. The gas phase was analyzed and ethylene, propane, ethane and methane were identified as main gas products in the product mixture at different reaction conditions. All catalysts were characterized by BET, ICP-AES, XRD, HRSEM, NH3-TPD, and pyridine-DRIFT technique. This high catalytic performance of the H-ZSM-5 catalyst is attributed to the presence the high mesopore volume and mesopore surface area, the mild acidity and the highest Brönsted to Lewis acid sites ratio (BAS/LAS) comparing with other studied zeolite catalysts. Based on the experimental results, the reaction pathway of tetralin transformation into BTX was proposed. Hydrocracking, ring opening, ring contraction, dehydrogenation/hydrogenation, alkylation/dealkylation, isomerization, and overcracking reactions were involved. Results were consistent with the occurrence of the monomolecular reaction mechanism.

Investigation of Ni–Fe–Cu-Layered Double Hydroxide Catalysts in Steam Reforming of Toluene as a Model Compound of Biomass Tar

This work focused on the synthesis of a catalyst based on layered double hydroxides with a molar cation concentration Ni/Cu/Fe/Mg/Al of 30/5/5/40/20 and its performance in the steam reforming of toluene as a model compound of biomass tar. Its performance at different temperatures (500, 600, 700, 800, and 900 °C) and steam/carbon molar ratios (S/C ratios) (1, 2, 4, 6, 8) was studied. The contact time used was 0.32 g h mol−1. The catalyst obtained allowed us to reach 98–99.87% gas conversion of toluene with a low carbon deposition on catalyst surface (1.4 wt %) at 800 °C and S/C = 4. In addition, conversions in the range of 600–700 °C were higher than 80% and 90%, respectively, and the type of carbon deposited on the catalyst was found to be filamentous, which did not significantly reduce the performance of the catalyst.

Catalytic hydrogenation, hydrocracking and isomerization reactions of biomass tar model compound mixture over Ni-modified zeolite catalysts in packed bed reactor

Gas-phase conversion of a model mixture of biomass tar (5 wt% naphthalene and 95 wt% of 1-methylnaphthalene) into 2-methylnaphthalene liquid product and ethylene and propane gas mixture was carried out over different zeolites and metal promoted zeolites in a packed-bed reactor for the first time. In the present work, a series of MFI (H-ZSM-5), BEA (H-β), FAU (H-Y, H-USY), and MOR (H-Mordenite) zeolites were investigated. The effect of Ni metal addition on the promotion of parent zeolite catalysts was studied. The most successful catalysts were characterized by BET, ICP-AES, XRD, HRSEM, STEM-HAADF, and STEM-BF with EDXS, NH3-TPD, H2-TPR, TGA, and pyridine-DRIFT techniques. The superior performance in comparison to the other studied catalysts was established over the 5 wt%Ni/H-ZSM-5 (SiO2/Al2O3 = 30) with 96.2 mol% of selectivity to 2-methylnaphthalene in the liquid phase, 90 mol% total conversion with the highest part (82.9 wt%) of ethylene and propane in the gas phase after 24 h time-on-stream. This high catalytic performance of the 5 wt%Ni/H-ZSM-5 catalyst can be attributed to the presence of the high mesopore volume, pore diameter, and high mesopore surface area, the existence of the redox active sites, and the presence of strong Lewis acid sites due to synergetic interaction between Ni metal species and zeolite acid support. Based on the product distributions observed, the reaction scheme of the conversion of biomass tar model mixture of naphthalene and 1-methylnaphthalene over studied catalysts was proposed. Our catalytic results obtained over pristine and Ni-modified zeolite catalysts shed light on the potential use of these catalysts in the biomass tar valorization process under atmospheric pressure.

Low-temperature catalytic steam reforming of toluene as a biomass tar model compound over three-dimensional ordered macroporous Ni-Pt/Ce1−xZrxO2 catalysts

Ceria–zirconia solid solution (Ce1−xZrxO2) is a fascinating catalyst support in steam reforming reaction. In order to further improve the performance of Ni-based catalyst with Ce1−xZrxO2 as support for tar team reforming, three-dimensional ordered macroporous Ni-Pt/Ce1−xZrxO2 (Ni-Pt/C1−xZx-3DOM; x = 0.2, 0.3, 0.4) catalysts were prepared by a colloidal crystal template method and their catalytic performances for toluene steam reforming were investigated in low temperature range. The Ni-Pt/C1−xZx-3DOM exhibited excellent catalytic performance, and toluene conversion of Ni-Pt/C0.8Z0.2-3DOM reached 90.4 % at 500 °C under 185 μmol/min toluene flowrate and 10,000 h−1 GHSV. Besides, this catalyst showed good durability with 1.7 mg gcat−1 h−1 carbon deposition rate during 30 h of operation at 600 °C. The characterization results demonstrated the Ni-Pt/C1−xZx-3DOM exhibits desirable characteristics to promote the catalysis performance compared to non-porous Ni-Pt/C1−xZx, including more oxygen vacancies on catalyst surface, higher specific surface areas, larger pore volumes, more meso-pores, smaller crystalline size of active component and support, and better reducibility.

Direct Reduction Ironmaking by Co-Pyrolysis of Biomass Tar Model Compounds and Iron Ore Fines

The low carbon metallurgy technology based on the high-value utilization of biomass is considered as the key development orientation of green ironmaking. In this paper, a pyrolysis coupling technology of biomass tar and iron ore powder is proposed for the reduction of iron ore. Tar is degraded efficiently due to the synergy effects respectively through oxidation of iron oxides and the catalytic action of reduced iron, and simultaneously the reduction of iron oxide to metallic iron. Representative tar components including vanillin, naphthalene, and catechol were selected as tar model compounds. The various reaction conditions on the reduction degree of iron ores was investigated, which include the type of tar component, the pyrolysis temperature, and the ratio of reactants. According to the results, the optimal relationship between tar degradation and reduction of iron ore was identified. It can be found that under the catalytic effects of iron ore fines, the degradation efficiency of the three model compounds followed the following order: naphthalene > vanillin > catechol. Naphthalene owned the better reduction ability. The highest reduction degree of the product reached to 78.5% at 800 °C for 30 min.

One-step preparation of a N-CNTs@Ni foam electrode material with the co-production of H2 by catalytic reforming of N-containing compound of biomass tar

Carbon nanotubes (CNTs) can be formed during catalytic reforming of hydrocarbons with H2 co-production over Ni-based catalysts. Normally, the formed CNTs need to be separated from original catalysts in order to be coated on the substrates to make high performance electrodes. To simplify the traditional preparation process, a novel one-step method for simultaneously producing a CNTs electrode material and H2 was proposed. A Ni-Fe modified Ni foam (Ni-Fe/NF) was chosen as both catalyst and electrode substrate to in situ grow nitrogen-doped carbon nanotubes (N-CNTs) during catalytic reforming of pyrrole. Pyrrole was selected as an N-containing model compound of biomass tar. The results showed that Ni-Fe nanoparticles on Ni-Fe/NF catalyst remarkably improved the H2 production and pyrrole conversion, which increased by more than 20 times than those of fresh Ni foam. Besides, a significant amount of multi-walled CNTs with more than 40 graphite layers grew on the surface of spent catalyst and their diameters were mainly from 10 nm to 20 nm. N element was detected on the formed CNTs and the Graphitic-N was the main type of N-doping. The spent catalyst (N-CNTs@Ni foam) can be directly used as a composite electrode material with high performance and stability. Its electrochemical capacitance reached 855 mF/cm2 at a current density of 5 mA/cm2 and remained over 95% after 10,000 cycles.

Steam reforming of toluene over nickel catalysts supported on coal gangue ash

Abstract The development of high performance and low-cost catalyst is very important to remove tar during biomass gasification. Solid waste coal gangue ash (CGA), which mainly contains SiO2, Al2O3, Fe2O3 and CaO, was selected as support for Ni-based catalyst. The prepared low-cost catalysts were characterized suitably by XRD, BET, TPR, SEM, TG and Raman techniques. Toluene was selected as typical biomass tar model compounds to test the catalyst performance and compared with traditional catalysts Ni/Al2O3 and Ni/SiO2. Ni/CGA-1d exhibited the highest catalytic performance with the toluene conversion and H2 yield accounting for 91.5% and 58.2% respectively, at 800 °C. It was showed that the performance of Ni/CGA-1d was higher than traditional catalysts Ni/Al2O3 and Ni/SiO2, and comparable with other polymetallic reforming catalysts. Due to the good resistance of carbon deposition, the Ni/CGA-1d catalyst also performed better catalytic activity stability. The ability should be attributing to the existence of some metal elements such as Fe, Mg, K, Ca et al. in coal gangue ash support.

Carbon-coated mesoporous silica-supported Ni nanocomposite catalyst for efficient hydrogen production via steam reforming of toluene

Catalytic steam reforming of biomass tars is a promising technique for H2-rich gas production. However, the undesired deactivation of nickel-based catalysts due to nanoparticle (NP) sintering and carbon deposition remains a challenge for industrial applications. In this study, we prepared a carbon-coated ordered mesoporous silica-supported Ni-based catalyst (Ni-SiO2@C) via an evaporation-induced self-assembly (EISA) and calcination process. Characterizations revealed that the Ni-SiO2@C has a regular mesostructure with graphitic carbon layers protected Ni NPs (average 5.5 nm in diameter) highly dispersed and embedded into the silica wall of mesoporous channels. Compared to the SBA-15 and activated carbon-supported catalysts (NiO/SBA-15 and Ni/AC), the Ni-SiO2@C exhibits a higher toluene (a biomass tar model compound) conversion efficiency of 99.9% at 550 °C with an excellent stability for at least 46 h during steam reforming. The good performance can be attributed to the improved Ni NP dispersion, electron transfer and hydrothermal stability by enhanced metal-support interaction (MSI) as well as carbon coating. This work provides a cost-effective and easy handling approach for the synthesis of anti-sintering and coke-resistant tar reforming catalysts.

Pyrolysis char derived from waste peat for catalytic reforming of tar model compound

The pyrolysis char derived from solid waste peat was used in the removal of biomass tar. A laboratory dual-stage reactor was designed to obtain a cost-effective and eco-friendly tar removal approach using peat pyrolysis char-based catalyst. Rich pore structure of pyrolysis char can enhance the adsorption and removal performance of tar, the KOH and CO2 activation method were used to increase the pore structure of pyrolysis char. Toluene was chosen as the model compound of biomass tar for basic research. The effects of pyrolysis char and transition metal Fe on toluene removal were studied. The investigated reforming parameters were reaction temperature (700–900 °C), residence time (0.3–0.8 s) and steam-to-carbon ratio (1.5:1–4:1). The results indicated that the peat pyrolysis char-based Fe catalysts showed excellent catalytic performance (toluene conversion >89%) and gas selectivity, especially the catalyst that activated by CO2 had the best selectivity for syngas (88.1 mol%), and the waste peat catalyst was compared with other waste pyrolysis char-based catalysts. Textural characterization showed that the excellent catalytic activity and stability of the catalysts are due to the presence of FeC and FeSiO3 structures. Such the peat pyrolysis char can as a carrier be used to remove tar and produce high content syngas in pyrolysis process.

Microwave reforming with char-supported Nickel-Cerium catalysts: A potential approach for thorough conversion of biomass tar model compound

Tar abatement and removal is most challenging facing industrialization of biomass gasification technology and its cost-effective removal is indispensably dreamed. Thorough, low-cost and stable removal of toluene, a major compound of biomass tar, was achieved by the microwave catalytic reforming method. A self-designed microwave tube furnace was employed, and toluene was converted with char-supported nickel-iron and nickel-cerium catalysts in an ex situ hot gas conditions. Under the optimal conditions, a 100% toluene conversion efficiency could be achieved, and the hydrogen concentration in the product gas could reach 28.2 vol%. The energy efficiency was 98.97 g/kW h. According to duration tests, the conversion efficiency of nickel-cerium catalysts could still be higher than 90%, even after 8-h successive runs. Comprehensive characterizations of fresh and spent catalysts were conducted, showing agglomeration was the main challenge instead of carbon deposition, which was previously commonly believed. Furthermore, in the pursuit of advancing industrial tar abatement, the depletion and thermal stability of char-supported catalysts were evaluated through a custom-designed gasification-atmosphere-thermogravimetry-mass spectrum analysis. The study provided a breakthrough for the integration of thermal, catalysis and microwave effects for toluene conversion, and the mechanism of char-supported catalysis under specific microwave conditions was also highlighted.

In-situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier

Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.

Exploring the Conversion Mechanisms of Toluene as a Biomass Tar Model Compound on NiFe2O4 Oxygen Carrier

As a novel biomass gasification technology, chemical looping gasification (CLG) could in situ catalytically crack biomass tar by oxygen carrier (OC). This study compares the reactivity of different OCs (Al₂O₃, Fe₂O₃, NiO, NiO+Fe₂O₃, and NiFe₂O₄) to crack a biomass tar model compound (toluene) and preliminarily explores the reaction mechanisms of toluene cracked by NiFe₂O₄ OC. Among five OCs, NiFe₂O₄ with a homogeneous Fe/Ni dispersibility shows the best reactivity for toluene cracking with a toluene conversion and H₂ yield of 96.83% and 0.91 L/g, respectively. Additionally, on the basis of the dispersibility of active sites on the OC sample surface, the reactivity of the other four OCs to crack toluene shows the sequence NiO+Fe₂O₃ > Fe₂O₃ > NiO ≫ Al₂O₃. A large amount of carbon deposition, including amorphous carbon and graphitized carbon, is generated during toluene catalytic cracking, while the addition of steam significantly eliminates the carbon deposition. The NiFe₂O₄ OC shows a dual-function of in situ oxidation–catalysis during toluene cracking. A mechanism of four steps is proposed for the toluene cracking on OCs: (I) toluene cracking at high temperature, (II) reduction of OC, (III) generation of amorphous carbon deposition and (III′) formation of graphitized carbon, and (IV) elimination of carbon deposition.

Removal of biomass tar model compound using reverse vortex flow gliding arc discharge

ABSTRACT Removal of tar derived from biomass gasification using plasma discharge was of great interest. In this work, treatment of biomass tar using a high flow rate, reverse vortex flow gliding arc discharge (RVF-GA) was investigated. Naphthalene was used as a light tar model compound. Investigation was carried out at different inlet tar concentrations, total gas feed rates, and applied energy inputs. The naphthalene concentrations considered were low (≈ 610 mg/m3), moderate (≈ 4,330 mg/m3) and high concentration (≈ 10,330 mg/m3). It was demonstrated that the RVF-GA reactor performed well in removal of tar at high flow rates. The removal efficiency in the range of 75–95%, the specific energy input in the range of 0.11–0.33 kWh/m3 and the energy utilization in the range of 1.4–112 g/kWh could be achieved. The plasma assisted decomposition of naphthalene was found to increase with the applied electrical energyinput.

Enhanced reforming of mixed biomass tar model compounds using a hybrid gliding arc plasma catalytic process

Abstract Plasma-catalytic steam reforming of mixed tar model compounds (toluene and naphthalene) from biomass gasification has been carried out in a gliding arc discharge (GAD) plasma reactor. The influence of three catalysts (15Ni, 7.5Ni7.5Co and 15Co) on the performance of the plasma reforming of toluene and naphthalene has been evaluated including the conversion, the energy efficiency, the yield/selectivity of gaseous products and the formation of by-products. A plasma-catalysis synergy was generated when introducing the catalysts to the plasma tar reforming process. The highest toluene conversion of 95.7% and naphthalene conversion of 83.4% were achieved when the 7.5Ni7.5Co catalyst was integrated with the GAD plasma at a total tar concentration of 16.0 g/Nm3 and a discharge power of 75 W. The corresponding energy efficiency for the conversion of toluene and naphthalene was 38.0 g/kWh and 2.3 g/kWh, respectively, giving the highest total tar conversion of 95.1% and overall energy efficiency of 40.3 g/kWh. The coupling of GAD with the 7.5Ni7.5Co catalyst also showed the highest yield of H2 (42.3%) and CO (37.3%) and the highest CO selectivity of 40.1%. In addition, the combination of the GAD plasma with 7.5Ni7.5Co reduced the carbon deposition on the catalyst surfaces and the formation of by-products in the plasma-catalytic tar reforming process. The enhanced reducibility and NiCo alloy formation of the 7.5Ni7.5Co catalyst contribute to the enhanced conversion of mixed tar compounds and the formation of the plasma-catalysis synergy in the hybrid plasma-catalytic tar reforming process.

Synthesis of graphitic mesoporous carbon supported Ce-doped nickel catalyst for steam reforming of toluene

Graphitic mesoporous carbon (GMC) supported Ce-doped nickel catalyst was prepared by a simple incipient wetness impregnation and calcination method. The catalytic performance of the prepared catalyst was tested by catalytic steam reforming of toluene (a biomass tar model compound). Compared with mesoporous SBA-15 supported catalyst, the GMC supported catalyst has a higher toluene conversion efficiency of 98% at 700 °C and remained stable during 24 h of continuous reaction. The excellent catalytic performance is mainly attributed to the better dispersion of Ni nanoparticles on GMC support and the reduced carbon deposition because of the Ce-doping.

NiCo@NiCo phyllosilicate@CeO2 hollow core shell catalysts for steam reforming of toluene as biomass tar model compound

Developing sintering and carbon resistant tar removal catalysts is crucial for biomass gasification technology. Herein, for the first time, NiCo@NiCo phyllosilicate@CeO2 hollow core shell catalysts have been designed for steam reforming of toluene (SRT) as the biomass tar model compound. They show both good catalytic activity and stability within 45 h of time on stream due to their high sintering resistance of NiCo because of the strong interactions between NiCo and CeO2, high metal exposure as a result of the high specific surface area, high surface metal concentration as well as the high oxygen vacancies as evidenced from the H2-Temperature-programmed reduction (H2-TPR), H2 chemisorption and X-ray photoelectron spectroscopy (XPS) characterizations respectively. Additionally, the synergistic effect between Ni and Co further improves their carbon resistant property. By comparison, Co@Co phyllosilicate@CeO2 catalysts perform the lowest toluene conversion and stability mainly due to their structural instability during reaction resulting from their high Si/Co ratio, leading to their low specific surface area and Co exposure. The outstanding SRT performance of NiCo@NiCo phyllosilicate@CeO2 catalysts indicates their promising application for steam reforming of biomass tar reaction.

High catalytic performance of Fe-Ni/Palygorskite in the steam reforming of toluene for hydrogen production

The inexpensive and abundant material, palygorskite, was used as a promising catalyst support to prepare Fe-Ni/Pal catalysts. Catalytic steam reforming of toluene as a biomass tar model compound over these catalysts was investigated in a fixed-bed reactor under different parameters, including reaction temperatures and S/C molar ratios. The stability and lifetime of Fe3Ni8/Palygorskite catalyst was evaluated under optimal conditions and its kinetic parameters were determined as well. The fresh and used catalysts were characterized using X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), transmission electron microscopy (TEM), and Raman spectra. The results showed that the Fe3Ni8/Palygorskite catalyst with high dispersion was successfully prepared and exhibited superior catalytic performance compared with those of the monometallic catalysts (Fe3/Palygorskite and Ni8/Palygorskite) and the bare Palygorskite. Increasing the reaction temperature from 500 °C to 700 °C was beneficial for the toluene conversion and gaseous yields. The catalytic activity of Fe3Ni8/Palygorskite varied distinctly with the increase of S/C molar ratio and reached maximum at the the S/C molar ratio of 1.0. The apparent activation energy of 41.55 kJ mol−1 and the pre-exponential factor of 1.35 × 103 m3 kg−1 h−1 were obtained for Fe3Ni8/Palygorskite in kinetic studies under optimal reaction conditions, respectively. The carbon deposition analysis of the used catalysts revealed that the formation of graphitic carbon rather than amorphous carbon was the main reason for the deactivation of Fe3Ni8/Palygorskite catalysts. When ceased the injection of steam into the reaction system, the graphitic carbon would be accelerating formed on the surface of the Fe3Ni8/Palygorskite and decreased its catalytic activity for toluene conversion. But owing to the water gas shift reaction, the catalytic activity of Fe3Ni8/Palygorskite seemed to recover gradually to its optimum.