Tar Steam 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.

Tar microwave reforming over different biochar-based Ni catalysts by experiments and DFT

In order to remove tars generated during biomass pyrolysis. In this study, tar steam reforming was investigated using toluene as a tar model compound and a biochar-based nickel catalyst under microwave conditions. Based on the catalyst characterization results, density functional theory (DFT) calculations were performed to investigate the effect of different forms of nickel presence in the catalyst on toluene cracking. The experimental and simulation results indicate that the formation of Ni3S2 negatively affects the cracking of toluene. The catalyst prepared by Ni(NO3)2 impregnation demonstrated relatively good catalytic activity and stability, with 81.6 % conversion even after 190 min of pyrolysis. The ratio of water to carbon (S/C) has a significant impact on the steam reforming of toluene. A high S/C can lead to the destruction of the catalyst carbon matrix, resulting in catalyst deactivation. Conversely, a low S/C can cause a slow increase in the catalytic effect of the catalyst. The catalytic effect of the Ni(NO3)2 catalytic remains good even without the addition of water, with 78.6 % hydrogen conversion remaining at the end of 190 min pyrolysis. The addition of water molecules will inhibit the production of CH4.

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.

Continuous coke management with Ni and Ni-Co catalysts for bio-syngas tar steam reforming – The Switch-SRCG unit

Continuous coke management with Ni and Ni-Co catalysts for bio-syngas tar steam reforming – The Switch-SRCG unit

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.

Construction and reaction characteristics of pyrochlore-supported Ni catalysts for tar steam reforming

Tar is a common by-product during the gasification of biomass and its presence largely limits the subsequent application of syngas generated. Although biomass tar could be converted into hydrogen-rich syngas by catalytic steam reforming, the frequently adopted high-activity and low-cost Ni catalysts suffer from the problem of easy deactivation as a result of carbon deposition, and more efficient and stable catalyst needs to be developed for tar removal in biomass gasification. In the work, various Ni/pyrochlore catalysts characterized with redox properties were constructed and further modified through partial replacement of A-site in support, and their reaction characteristics in toluene steam reforming were comprehensively investigated. Results show that catalysts of Ni/La2Ce2 and Ni/Y2Ce2 have good catalytic performance due to the strong interaction between Ni and pyrochlore. Although a small amount doping of Sr in A-site is observed to decrease Ni/pyrochlore interaction, the great promotion in surface oxygen mobility make Ni/La1.8Sr0.2Ce2 possess the best reactivity among all catalysts studied, and the optimum operating conditions is determined to be 650 °C and S/C = 2. Moreover, Ni/La1.8Sr0.2Ce2 is found to be very stable during toluene steam reforming, which is proved to be a result of the superior capability in resisting coke formation.

Recent progress on catalyst development in biomass tar steam reforming: toluene as a biomass tar model compound

Recent progress on catalyst development in biomass tar steam reforming: toluene as a biomass tar model compound

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.

Plasma-catalytic steam reforming of benzene as a tar model compound over Ni-HAP and Ni-γAl2O3 catalysts: Insights into the importance of steam and catalyst support

Non-thermal plasma (NTP) coupled Ni-based catalysts are a promising method for tar steam reforming to syngas. In this work, Ni-based catalysts supported on hydroxyapatite (Ni-HAP) and γAl2O3 (Ni-γAl2O3) coupled with a coaxial dielectric barrier discharge (DBD) plasma were used to degrade biomass tar, and benzene was selected as a typical unbranched benzene ring structured tar model compound. In the NTP alone system, an increase in discharge power leads to benzene deep cracking to carbon deposition. In the NTP-catalytic system, the reaction temperature is a critical factor for catalysis, and the catalyst leads to a significant increase in benzene conversion and total gas yield, prompting the conversion of more cracking intermediates to gaseous products. Steam in the system has both positive and negative effects: a certain amount of steam can increase the amount of H· and ·OH, promoting benzene decomposition and carbon deposit elimination; excessive steam will compete for energetic electrons or oxidize the active metal in the catalyst, inhibiting benzene conversion. The Ni3-HAP catalyst exhibits the maximum benzene conversion (92.13 %) and energy efficiency (8.49 g/kWh), thanks to the formed Ni2+[I] and Ni2+[II] in the lattice due to the flexible ion exchange properties of the HAP support. The main reason for the catalyst activity degradation is carbon deposition rather than catalyst sintering. A good match among tar conversion rate, degree of decomposition, steam content and steam decomposition rate is critical for efficient and stable operation of the NTP-catalytic system.

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.

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.

Tunable syngas production from biomass: Synergistic effect of steam, Ni–CaO catalyst, and biochar

The production of tunable syngas from biomass will further establish the role of biomass-derived syngas as a versatile platform for liquid fuels and value-added chemical synthesis. This study introduced steam, Ni–CaO catalyst, and biochar into a proposed two-stage sorption-enhanced catalytical thermochemical conversion process, aiming to obtain the tunable syngas through the in-situ stepwise generation of high purity H2 and CO. The presence of steam and Ni–CaO catalyst shows unprecedented performance in enhancing the H2 generation due to the promotional tar steam reforming/cracking and water-gas shift reactions at the first stage, and the control experiments indicate that the steam performs a higher selectivity to H2 than the Ni–CaO catalyst. The introduction of biochar with a supplementary carbon source, remarkably promotes the CO generation at the second stage, which could be further pronounced by the addition of Ni–CaO catalyst. A synergistic effect of steam, Ni–CaO catalyst, and biochar contributes to a significant enhancement in H2 and CO generation with an inherently separated generation of H2 (88.2 ± 2.3 vol% of purity) and CO (55.6 ± 1.3 vol% of purity). And the combined use of steam, Ni–CaO catalyst, and biochar could lead to a superior syngas quality with high LHVsyngas and energy recovery efficiency.

Development of a High Temperature CO2 Sorbent Based on Hydrotalcite for a H2-Rich Syngas Production

To adapt hydrotalcite-based sorbents (also known as layered double hydroxides—LDHs) to high-temperature CO2 sorption compatible with tar steam reforming, the addition of CaO was investigated, maintaining the LHDs porosity and accessibility but mostly assuring the CO2 sorption stability during sorption/desorption cycles. In co-precipitation synthesis, the investigated parameters are (i) various interlayer anions with different sizes and valences (carbonate, oxalate, and stearate); (ii) various pH values; (iii) different Mg/Ca molar ratios. The characterization of these modified LDHs by TGA, XRD, N2 adsorption, SEM, sorption capacity, and sorption/desorption stability (cyclic TGA) allowed understanding the effect of the various synthesis parameters and highlighted the effect of oxalate use as the interlayer anion. After calcination of sorbent with Mg/Ca/Al ratio = 1/2/1, typical LDH sand roses were formed both with carbonate and oxalate anions: this former exhibited the highest sorption capacity and accessibility of CaO sites at 600 °C, higher than pure CaO. However, the best stability during cycles was obtained with the sorbent from oxalate and Mg/Ca/Al ratio = 1.5/1.5/1 at pH 10 for which comparable sorption results are reached. For these two samples, the observed macro-porosity was associated with the highest specific surface area and pore volume.Graphic Abstract

Comparative evaluation of tar steam reforming over graphitic carbon supported Ni and Co catalysts at low temperature

The development of cheap and highly dispersed nano-catalyst is one of the key technologies for low temperature steam reforming (SR) of biomass tar. This work used acid-washed and oxidized Shengli lignite char (OXAWSL) as carbon precursor to load Co (Co/OXAWSL) and Ni (Ni/OXAWSL) via ion exchange method to SR of toluene and biomass tar. The Co/OXAWSL was more active and stable than Ni/OXAWSL during the 30 h test with a final toluene conversion of 85% at a relatively low temperature of 450 °C and steam to carbon ratio (S/C) of 3.4, which resulted from its small particle size (5.6 nm) and high dispersion (12.3%) of Co. The relatively high H2 production (42.59 mmol/g-biomass) over Co0.1/OXAWSL (450 °C, S/C = 3.4) in SR of tar was also obtained. A low Ea (22.0 kJ/mol) value of Co/OXAWSL and good affinity to oxygen for Co explained its excellent performance. The low-temperature tar cracking process can provide theoretical and technical support for the large-scale industrial utilization of biomass pyrolysis and gasification.

Nickel supported over MCM-41 coated ceramic membrane for steam reforming of real tar

A novel catalyst, Nickel supported over MCM-41 coated ceramic membrane (NMC), was developed using coating method and deposition-precipitation method and applied for steam reforming of real tar in fixed bed. The effects of reaction conditions such as Ni loading amount, reaction temperature and mass ratio of steam to tar were also studied. The good dispersion of Ni nanoparticles and the strong interaction between Ni particles and the support were identified by BET, XRD, H2-TPR and SEM/EDS, resulting in the excellent performance of NMC catalysts. Maximum tar conversion of 96.4% and H2 yield of 98.7 mmol g−1 were obtained using 20NMC with a mass ratio of steam to coal tar of 2 at 800 °C. Moreover, 20 NMC exhibited a good stability in 10 h of lifetime test and the resistance of graphitic carbon formation prone to easier regeneration of catalysts illustrated by Raman spectroscopy. It indicates that the utilization of NMC catalysts for tar steam reforming is a promising way.

Tar steam reforming for synthesis gas production over Ni-based on ceria/zirconia and La0.3Sr0.7Co0.7Fe0.3O3 in a packed-bed reactor

In this work, NiO level was varied from 5 to 40% whereas CexZr1-xO2 (x = 0.5, 0.7 and 0.9) (CZO) and La0.3Sr0.7Co0.7Fe0.3O3 (LSCF) were chosen as two different kinds of support. Regardless the type of support, the surface NiO (at 40%) was completely reduced at 600 °C, giving the amount of activated Ni at 8950 μmol/gcat. The reducibility of the updoped LSCF was found to be much better than that of the undoped CZO, evidenced by the H2-TPR of the both materials at 600 °C where the oxygen storage capacity (OSC) of LSCF and CZO was determined at 4273 and 307 μmol/gcat, respectively. In contrast, the OSC of 40%Ni-CZO (where x = 0.7, 0.9) was found to be higher than that of the LSCF, implying that the addition of Ni more enhanced both electronic defect and oxygen mobility in CZO than in LSCF, according to the H2-TPR results. Coke resistant of CZO is presumable more satisfying than that of LSCF, thus, the longer lifespan of the CZO catalyst system is expected. The catalytic performance of 40%Ni-CZO (x = 0.9) was however comparable with 40%Ni-LSCF as they accommodate the same number of active sites. The slightly better catalytic performance of the 40%Ni-CZO (x = 0.9) could be due to its smaller crystallite size (CZO = 26.83, LSCF = 35.73), rendering more access for the relative gaseous reactants. The best catalyst amongst all was 5%Ni-CZO (x = 0.9), giving 89% toluene conversion, 46% H2 yield, 71% CO selectivity, and 25% CO2 selectivity at optimum reaction temperature of 700 °C.

Tar steam reforming during biomass gasification: kinetic model and reaction pathway

In this study, the steam reforming of naphthalene and pyrene as heavy tar model compounds was investigated experimentally in a horizontal tube reactor and theoretically using the CHEMKIN simulation. The experimental results revealed that the reactivity of naphthalene was higher than that of pyrene in the presence of steam. The carbon content converted to soot is a little more than that converted to light gas during tar steam reforming. The kinetic parameters of the overall reaction were determined, and the pre-exponential factor and activation energy were calculated using the experimental data. The comparison of the numerical simulation with the experimental findings exhibited an excellent agreement for the prediction of the light gas products and soot after eliminating the influence of the water–gas shift. Further, the reaction schemes including the reaction pathway and associated kinetics were determined for the steam reforming of these model compounds. Both naphthalene and pyrene exhibited a similar performance during the reaction in the presence of steam. Benzene and naphthalene, representing the precursors of the light gas product, were confirmed to be the dominant intermediate components of naphthalene and pyrene, respectively. The consecutive reactions of these intermediates subsequently resulted in the generation of the light gaseous products.

Role of phosphorus (P) additive in the performance of char-supported nickel (Ni) catalyst on tar reforming

Developing high-efficiency and low-cost tar removal catalysts is immediate and critical for gasification technology. In this work, phosphorus (P) was introduced into char-supported nickel (Ni) catalysts for steam reforming of tar. P and Ni were loaded on the catalyst support precursor, Yining coal oxidized by 20% H2O2, using two kinds of loading sequence, Ni, P co-loading and stepwise loading to obtain (P + Ni)/20%O-C and P-Ni/20%O-C catalysts respectively. Sand and Ni/γ-Al2O3 were selected for blank experiment and comparison. The self-designed dual-stage quartz reactor was used as an evaluation device to test tar steam reforming activity of the catalysts. Preparation conditions for catalyst and reaction technology were also optimized. The effect of P on the structure and acidity of catalysts was investigated by XRD, N2 adsorption, SEM, TEM, XPS, and NH3-TPD. It was found that (P + Ni)/20%O-C prepared by Ni, P co-loading method exhibited superior catalytic performance due to a better dispersion of Ni, more acid sites and higher amount of Ni0. Meanwhile, it is verified that pH 11 and 600 °C is the optimal preparation condition and reaction temperature. Compared to Ni/γ-Al2O3, the (P + Ni)/20% O-C catalyst achieved the highest reforming gas yield (39.3 mmol/g) and lowest tar yield (4.9%), which could be attributed to the function of conversion heavy tar to light fraction of (P + Ni)/20%O-C catalyst. That means most polycyclic materials cracked to small molecule products.