Screening of supported transition metal catalysts for hydrogen production from glucose via catalytic supercritical water gasification

In total 17 heterogeneous catalysts, with combinations of 4 transition metals (Ni, Ru, Cu and Co) and various promoters (e.g., Na, K, Mg, or Ru) supported on different materials (γ-Al₂O₃, ZrO₂, and activated carbon (AC)), were investigated with respect to their catalytic activity and stability for H₂ production from glucose via supercritical water gasification (SCWG). The experiments were carried out at 600 °C and 24 MPa in a bench-scale continuous-flow tubular reactor. Ni (in metallic form) and Ru (in both metallic and oxidized forms) supported on γ-Al₂O₃ exhibited very high activity and H₂ selectivity among all of the catalysts investigated for a time-on-stream of 5-10 h. With Ni20/γ-Al₂O₃ (i.e., γ-Al₂O₃ with 20 wt% Ni), a H₂ yield of 38.4 mol/kg glucose was achieved, approximately 20 times higher than that obtained during the blank test without catalyst (1.8 mol/kg glucose). In contrast, Cu and Co catalysts were much less effective for glucose SCWG reactions. As for the effects of catalyst support materials on activity, the following order of sequence was observed: γ-Al₂O₃ > ZrO₂ > AC. In addition, Mg and Ru were found to be effective promoters for the Ni/γ-Al₂O₃ catalyst, suppressing coke and tar formation.     

Novel highly efficient alumina-supported cobalt nitride catalyst for preferential CO oxidation at high temperatures

Novel alumina-supported cobalt nitride catalysts with Co loading ranging from 1 to 10 wt% prepared by NH₃-temperature-programmed reaction were investigated as potential catalysts for preferential CO oxidation (PROX) in excess H₂ at high temperatures. The formation of the Co₄N phase was confirmed by a combination of XRD and XPS, and the Co 2p binding energies of Co₄N reported previously were corrected to 798.2 ± 0.2 and 782.5 ± 0.2 eV. We observed that the catalytic activities of these nitrided Co/γ-Al₂O₃ catalysts were greatly related to their Co loadings. The nitrided 3 wt% Co/γ-Al₂O₃ catalyst showed the best PROX performance in temperature range of 200-220 °C, which was quite different from Co oxide precursor but was similar to Pt-group metals.     

The influence of Ni loading on coke formation in steam reforming of acetic acid

Steam reforming of acetic acid on Ni/γ-Al₂O₃ with different nickel loading for hydrogen production was investigated in a tubular reactor at 600 °C, 1 atm, H2O/HAc = 4, and WHSV = 5.01 g-acetic acid/g-cata.h^?1. The catalysts were characterized by temperature programmed oxidation (TPO) and differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that the amount of deposited carbidic-like carbon decreased and graphitic-like carbon increased with Ni loading increasing from 9 to 15 wt%. The Ni/γ-Al₂O₃ catalyst with 12 wt% Ni loading had higher catalytic activity and lower coke deposited rate.     

Hydrogen production by biomass gasification in supercritical water with bimetallic Ni-M/γAl2O3 catalysts (M = Cu, Co and Sn)

Supercritical water gasification (SCWG) of wet biomass is a very promising technology for hydrogen energy and the utilization of biomass resources. Ni-based catalysts are effective in catalyzing SCWG of original biomass and organic compounds for hydrogen production. In this paper, hydrogen production by SCWG of glucose over alumina-supported nickel catalysts modified with Cu, Co and Sn was studied. The bimetallic Ni-M (M = Cu, Co and Sn) catalysts were prepared by a co-impregnation method and tested in an autoclave reactor at 673 K with a feedstock concentration of 9.09 wt.%. XRD, XRF, N₂ adsorption/desorption, SEM and TGA were adopted to investigate the changes of chemical properties between Ni and Ni-M catalysts and the deactivation mechanism of catalysts. According to the experimental results, the hydrogen yield followed this order: Ni-Cu/γAl₂O₃ > Ni/γAl₂O₃ > Ni-Co/γAl₂O₃ > Ni-Sn/γAl₂O₃. The results show that Cu could improve the catalytic activity of Ni catalyst in reforming reaction of methane to produce hydrogen in SCWG. In addition, Cu can mitigate the sintering of alumina detected by SEM. Co was found to be an excellent promoter of Ni-based catalyst in relation to hydrogen selectivity.     

Hydrogen production by biomass gasification in supercritical water over Ni/γAl2O3 and Ni/CeO2-γAl2O3 catalysts

Hydrogen production by supercritical water gasification (SCWG) is a promising technology for wet biomass utilization. Ni catalyst can realize the high gasification efficiency of biomass near the critical temperature of water. In this paper, Ni/γAl₂O₃ and Ni/CeO₂-γAl₂O₃ catalysts were prepared by an impregnation method. The catalyst performance for glucose gasification in supercritical water was tested in autoclave reactor. All experiments were carried out in the autoclave at 673 K, 24.5 MPa, and the concentration of glucose was 9.09 wt.%. The catalysts before and after reaction were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET specific surface area measurements, X-ray fluorescence spectrum (XRF) and Thermo-gravimetric analyses (TGA) in order to investigate on the chemical property and catalytic mechanism. The experimental results showed that hydrogen yield and hydrogen selectivity increased sharply with addition of Ni/γAl₂O₃ and Ni/CeO₂-γAl₂O₃ catalysts. The catalytic activity and H₂ selectivity of Ni/CeO₂-γAl₂O₃ was higher than that of Ni/γ-Al₂O₃ catalyst. The results revealed that carbon deposition and coking led to the deactivation of the catalysts. Ce in the Ni/CeO₂-γAl₂O₃ catalyst had a certain role in the inhibition of carbon deposition and coking.     

Support and alloy effects on activity and product selectivity for ethanol steam reforming over supported nickel cobalt catalysts

Ni, Co and bimetallic Ni–Co catalysts supported on Ca-γ-Al₂O₃ and ZrO₂ were investigated for the production of hydrogen via ethanol steam reforming (ESR). Catalysts were prepared by wet impregnation method and characterized using temperature-programmed reduction (TPR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). ESR and temperature-programmed desorption of ethanol (ethanol-TPD) were carried out in a continuous flow fixed bed micro-reactor and the outlet gases were monitored by an on-line GC or MS. Ni is found to be more active for the C–C bond rupture than Co on both supports, Ca-γ-Al₂O₃ and ZrO₂. Catalyst support plays very important roles for the ESR. Strong interaction between support and metal affects the formation of NiCo bimetallic compound, resulting in the variety of catalytic activity. On Ca-γ-Al₂O₃ support, the catalytic activity of ESR follows the sequence of 10%Ni > 6.7%Ni 3.3%Co ∼ 3.3%Ni 6.7%Co > 10%Co. On ZrO₂, the trend is 10%Ni > 6.7%Ni 3.3%Co > 10%Co > 3.3%Ni 6.7%Co. The H₂O adsorption/activation ability of the support determines the reaction pathway and thus the product selectivity. On Ca-γ-Al₂O₃, water gas shift reaction is more favorable than on ZrO₂, due to the availability of surface OH groups. The roles of the metal and support for ESR are also discussed.     

Hydrogen generation from Al-Water reaction promoted by M-B/γ-Al2O3 (M = Co,Ni) catalyst

Al-water reaction promoted by catalysts is a promising hydrogen generation technology. In this work, a high-activity M-B/γ-Al₂O₃ (M = Co, Ni) catalyst is prepared by wet chemical reduction method. It is found that M-B/γ-Al₂O₃ catalyst significantly promotes the Al-water reaction and decreases the induction time. When the molar ratio of γ-Al₂O₃ to Co-M in Co–B/γ-Al₂O₃ catalyst is 1:1, the induction time is only 0.43 h. The catalytic activity of M-B/γ-Al₂O₃ is proportional to its active area. SEM analyses show that M-B particles are dispersed on γ-Al₂O₃ surface, which reduces the agglomeration of M-B and increases the active surface of M-B/γ-Al₂O₃, leading to a high catalytic activity. A possible mechanism is proposed, which shows that the dissociation of water molecules on γ-Al₂O₃ surface and the microgalvanic interaction between M-B and Al can promote the hydration process of passive oxide film on Al particle surface, speeding up the Al-water reaction.     

Coke-resistance enhancement of mesoporous γ-Al2O3 and MgO-supported Ni-based catalysts for sustainable hydrogen generation via steam reforming of acetic acid

Highly ordered mesoporous γ-Al₂O₃ particles and MgO materials were synthesized by evaporation induced self-assembly (EISA) and template-free hydrothermal co-precipitation routes, respectively. Ni, Ni–MgO, and Ni–La₂O₃-containing catalysts were prepared using a wet-impregnation method. The synthesized catalysts were characterized by N₂ adsorption–desorption, XRD, SEM-EDS, DRIFTS, XPS, TGA-DTA, and Raman spectroscopy analysis. The mesoporous γ-Al₂O₃ catalyst support exhibited a high surface area of 245 m²/g and average pore volume of 0.481 cm³/g. The DRIFTS results indicate the existence of large Lewis's acid regions in the pure γ-Al₂O₃ and metal-containing catalysts. Catalytic activity tests of pure materials and metal-containing catalysts were carried out at the reaction temperature of 750 °C and a feed molar ratio of AA/H₂O/Ar:1/2.5/2 over 3 h. Complete conversion of acetic acid and 81.75% hydrogen selectivity were obtained over the catalyst 5Ni@γ-Al₂O₃. The temperature and feed molar ratio had a noticeable impact on H₂ selectivity and acetic acid conversion. Increasing the water proportion in the feed composition from 2.5 to 10 considerably improved the catalytic activity by increasing hydrogen selectivity from 81.75% to 91%. Although the Ni-based γ-Al₂O₃-supported catalysts exhibited higher activity performance compared to the Ni-based MgO-supported catalysts, they were not as resistant to coke formation as were MgO-supported catalysts. The introduction of MgO and La₂O₃ into the Ni@γ-Al₂O₃ and Ni@MgO catalysts' structures played a significant role in lowering the carbon formation (from 37.15% to 17.6%–12.44% and 12.17%, respectively) and improving the thermal stability of the catalysts by decreasing the agglomeration of acidic sites and reinforcing the adsorption of CO₂ on the catalysts' surfaces. Therefore, coke deposition was reduced, and catalyst lifetime was improved.     

CO2 reforming of methane on Ni/γ-Al2O3 catalyst prepared by dielectric barrier discharge hydrogen plasma

Ni/γ-Al₂O₃ catalyst was prepared by direct treatment of Ni(NO₃)₂/γ-Al₂O₃ precursor with dielectric barrier discharge (DBD) hydrogen plasma at different input powers, characterized by XRD, H₂-TPR, CO₂-TPD, N₂ adsorption and TEM, respectively, and used as the catalyst for CO₂ reforming of methane (CRM). The results showed that the input power obviously affected the reduction degree and catalytic performances of catalysts. Low input power under 40 W mainly resulted in the decomposition of nickel nitrate into Ni oxides. The reduction degree, catalytic activity and stability increase with the input power. Similar catalytic performances in CRM reaction can be obtained when the power exceeds 80 W. Compared with the Ni/Al₂O₃ catalyst prepared by traditional method, Ni/γ-Al₂O₃ samples prepared by H₂ DBD plasma exhibit better activities, stability and anti-carbon deposit performances. It is mainly ascribed to smaller Ni particle size, more basic sites and weaker basicity. The increase of Ni particle sizes due to the sintering at high temperature results in the decrease of catalytic activities and coke formation.     

Evaluation of catalytic subcritical water gasification of food waste for hydrogen production: Effect of process conditions and different types of catalyst loading

Food waste is a kind of wet bio-waste which has been a challenge for the ecological environment and disposal. In this paper, hydrogen production from subcritical water gasification (SbWG) of food waste with and without catalyst loading was systematically investigated. The effects of reaction temperature (300–360 °C), residence time (30–90 min), food waste concentration (10–30 wt%) and catalysts (Ni/γ-Al₂O₃, Ni/ZrO₂, NaOH, KOH, and FeCl₃) were studied within a pressure range of 10.5–20 MPa. The optimal process condition for SbWG of food waste without catalysts loading was determined to be 360 °C and 90 min with 10 wt% food waste. The liquid products and hydrochar were characterized by TOC, TGA/DTG, and SEM. The TOC concentration of liquid products decreased vastly with increasing reaction temperature. The highest H₂ yield (1.88 mol/kg), H₂ mole fraction (35.01%), and H₂ selectivity (53.86%) were achieved at 360 °C for 90 min with 5 wt% loading of KOH. It can be concluded that the performance of the catalysts for improving hydrogen production in SbWG of food waste was in the following order: KOH > NaOH > Ni/γ-Al₂O₃ > Ni/ZrO₂ > FeCl₃. The catalytic SbWG can be a potential alternative for energy conversion of food waste and hydrogen production.     

Steam reforming of dimethyl ether over Cu–Ni/γ-Al2O3 bi-functional catalyst prepared by deposition–precipitation method

Cu–Ni/γ-Al₂O₃ catalysts with different metal contents for dimethyl ether steam reforming (DME SR) were prepared by the method of deposition–precipitation. Characterization of specific surface area measurement (BET), X-ray diffraction (XRD) and hydrogen temperature-programmed reduction (H₂-TPR) revealed that nickel improved the dispersion of copper, increased the interaction between copper and γ-Al₂O₃, and therefore, inhibited the sintering of copper. Ammonia temperature-programmed desorption (NH₃-TPD) showed that metal particles could occupy the acid sites, leading to the decrease in acid amount and acid strength of Cu–Ni/γ-Al₂O₃ catalyst. Kinetic measurements indicated that γ-Al₂O₃ is vital for DME SR and a higher content of γ-Al₂O₃ in catalyst was needed. The addition of nickel suppressed the water gas shift (WGS) reaction. Initial durability testing showed that the conversion of DME over Cu–Ni/γ-Al₂O₃ catalyst was always almost complete during the 30 h experimental reaction time. Therefore, Cu–Ni/γ-Al₂O₃ could be a potential DME SR catalyst for the production of hydrogen.     

Evaluation of Ni/Y2O3/Al2O3 catalysts for hydrogen production by autothermal reforming of methane

Ni/xY₂O₃–Al₂O₃ (x = 5, 10, 15, 20 wt%) catalysts were prepared by sequential impregnation synthesis. The catalytic performance for the autothermal reforming of methane was evaluated and compared with Ni/γ-Al₂O₃ catalyst. The physicochemical properties of catalysts were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-Ray Photoelectron Spectrometer (XPS), Thermo Gravimetric Analyzer (TGA) and H₂-temperature programmed reduction techniques (TPR). The decrease of nickel particle size and the change of reducibility were found with Y modification. The CH₄ conversion increased with elevating levels of Y₂O₃ from 5% to 10%, then decreased with Y content from 10% to 20%. Ni/xY₂O₃–Al₂O₃ catalysts maintained high activity after 24 h on stream, while Ni/Al₂O₃ had a significant deactivation. The characterization of spent catalysts indicated that the addition of Y retarded Ni sintering and decreased the amount of coke.     

Properties of Ni/Y2O3 and its catalytic performance in methane conversion to syngas

Ni/Y₂O₃, with Y₂O₃ support prepared by the conventional precipitation method, was prepared by an impregnation method. The physicochemical properties of Y₂O₃ and Ni/Y₂O₃ were characterized by BET, CO₂-TPD, NH₃-TPD, TPR, XRF and TGA, and compared with those of γ-Al₂O₃ and Ni/γ-Al₂O_3, respectively. The catalytic performance of Ni/Y₂O₃ in the reaction of partial oxidation of methane (POM) to syngas was evaluated and compared with that of Ni/γ-Al₂O₃ catalyst, too. The results showed that, Y₂O₃ was a basic support with few acidic sites while γ-Al₂O₃ was an acidic support. NiO particles supported on Y₂O₃ were more easily to be reduced than those supported on γ-Al₂O₃. In the partial oxidation of methane, Ni/Y₂O₃ catalyst showed high catalytic activity and exhibited better catalytic stability than Ni/γ-Al₂O₃. After POM reaction at 700 °C for 550 h, methane conversion decreased little and only 2.2 wt% carbon was deposited on Ni/Y₂O₃ catalyst. Ni/Y₂O₃ was stable in POM even after a series of reaction temperature variations within the temperature range of 400 ∼ 800 °C.     

An investigation on the role of ytterbium in ytterbium promoted γ-alumina-supported nickel catalysts for dry reforming of methane

Addition of low quantities of ytterbium to sol–gel prepared Ni/γ-Al₂O₃ catalysts has been shown to lead to significant increases in catalytic activity and long term stability in the catalytic conversion of CO₂ and CH₄ into syngas (H₂ and CO). The role of ytterbium in these catalysts was investigated in this study through detailed investigations on the structure and composition of ytterbium promoted Ni/γ-Al₂O₃ catalysts using the following techniques: synchrotron X-ray diffraction, X-ray Photoemission Spectroscopy, Transmission Electron Microscopy, Scanning Electron Microscopy/Energy Dispersive X-ray analysis, Temperature Programmed Reduction techniques and N₂ adsorption–desorption isotherms. The results obtained indicated that ytterbium, at small quantities (up to 2 wt%), interacted strongly with the support which in turn altered the interaction between nickel and the support (most notably it was found to completely inhibit the formation of NiAl₂O₄). This decreased interaction between Ni and the support also led to a higher quantity of Ni being present in the catalyst in the form of Ni.     

Modification effect of natural mixed rare earths on Co/γ-Al2O3 catalysts for CH4/CO2 reforming to synthesis gas

The study first investigated the modification effect of natural mixed rare earths (MRE) on cobalt catalysts for CH₄/CO₂ reforming to synthesis gas. The Co/γ-Al₂O₃ catalysts modified with the natural mixed rare earths were synthesized by the impregnation method, and characterized via ICP, BET, XRD, H₂-TPR, TEM and TG–DSC techniques. The result showed that the addition of mixed rare earths enhanced the anti-sintering ability of metallic cobalt after reduction and improved anti-coke performance of the catalysts via the synergic effect of mixed rare earths. The 20% Co/γ-Al₂O₃ catalyst promoted by the appropriate natural mixed rare earths exhibited good activity and stability with low carbon formation at 800 °C for 320 h reaction.     

Effect of Pr addition on the properties of Ni/Al2O3 catalysts with an application in the autothermal reforming of methane

Ni/xPr-Al₂O₃ (x = 5, 10, 15, 20 wt%) catalysts with an application in autothermal reforming of methane were prepared by sequential impregnation synthesis; its catalytic performance was evaluated and compared with that of Ni/γ-Al₂O₃ catalyst; the physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-Ray Photoelectron Spectrometer (XPS), Thermo Gravimetric Analyzer (TGA) and H₂-temperature programmed reduction techniques (TPR). The results showed that Pr addition promoted the reduction of nickel particle size on the surface. TPR experiments suggested a heterogeneous distribution of nickel oxide particles over xPr-Al₂O₃ supports and the promotion of NiO reduction by Pr modification. The CH₄ conversion increased with elevating levels of Pr addition from 5% to 10%, then decreased with Pr content from 10% to 20%. For the stability catalytic tests, Ni/xPr-Al₂O₃ catalysts maintained the high activity after 48 h while Ni/Al₂O₃ had a significant deactivation.     

Steam reforming of acetic acid using Ni/Al2O3 catalyst: Influence of crystalline phase of Al2O3 support

Ni-based catalysts supported on various alumina supports with different crystalline phases (γ-, α-, θ- and δ-Al₂O₃) were prepared and the effects of crystalline phases on the catalytic performance towards acetic acid steam reforming (AASR) were investigated. An acetic acid conversion of nearly 100% was observed in all the four catalysts, and their hydrogen selectivities were in the following order: Ni/α-Al₂O₃ (90%) > Ni/γ-Al₂O₃ (79%) > Ni/δ-Al₂O₃ (53%) > Ni/θ-Al₂O₃ (25%). Using different characterization methods, the inner relationship between catalyst crystalline phase and catalytic properties was determined. Through TEM, H₂-TPR and XPS characterization, Compared with α-Al₂O₃, on the surface of other crystalline phases of Al₂O₃ support were formed NiAl₂O₄ which indicated stronger interaction intensity between these supports and Ni., and that would reduce the formation of metallic Ni. It was confirmed that metallic Ni played a core role of catalytic AASR. More metallic Ni content caused better CC bonds and CH bonds breaking capability and eventually enhanced the selectivity towards hydrogen. That would be the key reason for Ni/α-Al₂O₃ showed best hydrogen selectivity among these four catalysts.     

Autothermal reforming of iso-octane and gasoline over Rh-based catalysts: Influence of CeO2/γ-Al2O3-based mixed oxides on hydrogen production

Autothermal reforming (ATR) of iso-octane in the presence of Rh-based catalysts (0.5 wt% of Rh) supported onto γ-Al₂O₃, CeO₂, and ZrO₂ were initially carried out at 700 °C with a S/C ratio of 2.0, an O/C ratio of 0.84, and a gas hourly space velocity (GHSV) of 20,000 h⁻¹. The activity of Rh/γ-Al₂O₃ was found to be higher than Rh/CeO₂ and Rh/ZrO₂, with H₂ and (H₂ + CO) yields of 1.98 and 2.48 mol/mol C, respectively, after 10 h. This Rh/γ-Al₂O₃ material, however, was potentially susceptible to carbon coking and produced 3.5 wt% of carbon deposits following the reforming reaction, as evidenced by C, H, N, and S elemental analysis. In contrast, Rh/CeO₂ catalyst exhibited lower activity but higher stability than Rh/γ-Al₂O₃, with nearly no carbon being formed within 10 h. To combine the superior activity originated from Rh/γ-Al₂O₃ with high stability from Rh/CeO₂, Rh/CeO₂/γ-Al₂O₃ catalysts with different CeO₂ contents were synthesized and examined for the ATR reactions of iso-octane. Compared to Rh/γ-Al₂O₃, the newly prepared Rh/CeO₂/γ-Al₂O₃ catalysts (0.5 wt% of Rh and 20 wt% of CeO₂) showed even enhanced activity during 10 h, and H₂ and (H₂ + CO) yields were calculated to be 2.08 and 2.62 mol/mol C, respectively. In addition, as observed with Rh/CeO₂, the catalyst was further found to be stable with less than 0.3 wt% of carbon deposition after 10 h. The Rh/γ-Al₂O₃ and Rh/CeO₂/γ-Al₂O₃ catalysts were eventually tested for ATR reactions using commercial gasoline that contained sulfur, aromatics, and other impurities. The Rh/γ-Al₂O₃ catalyst was significantly deactivated, showing decreased activity after 4 h, while the Rh/CeO₂/γ-Al₂O₃ catalyst proved to be excellent in terms of stability against coke formation as well as activity towards the desired reforming reaction, maintaining its ability for H₂ production for 100 h.     

Highly stable and active Ni-mesoporous alumina catalysts for dry reforming of methane

Nanostructured Ni-incorporated mesoporous alumina (MAl) materials with different Ni loading (7, 10 and 15 wt %) were prepared by a template assisted hydrothermal synthesis method and tested as catalysts for CO₂ reforming of methane under different conditions (nickel loading, gas hourly space velocity (GHSV), reaction temperature and time-on-stream (TOS)). The most active catalyst tested (Ni(10 wt%)-MAl) showed a very high stability over 200 h compared to a Ni(10 wt%)/γ-Al₂O₃ prepared using a co-precipitation method which had a significant loss in activity after only ∼4 h of testing. The high stability of the Ni-MAl materials prepared by the template assisted method was due to the Ni nanoparticles in these catalysts being highly stable towards migration/sintering under the reaction conditions used (800 °C, 52,000 mL h⁻¹ g⁻¹). The low susceptibility of the Ni nanoparticles in these catalysts to migration/sintering was most likely due to a strong Ni-support interaction and/or active metal particles being confined to the mesoporous channels of the support. The Ni-MAl catalysts also had significantly lower amounts of carbon deposited compared to the catalyst prepared using the co-precipitation method.     

Effects of Y2O3-modification to Ni/γ-Al2O3 catalysts on autothermal reforming of methane with CO2 to syngas

The effects of Y₂O₃-modification to Ni/γ-Al₂O₃ catalysts on autothermal reforming of methane to syngas were investigated. It was found that the introduction of Y₂O₃ (5%, 8%, 10%) lead to significant improvement in catalytic activity and stability, and the H₂/CO ratio could be adjusted via controlling the O₂/CO₂ ratio of the feed gas. According to the characterization results of catalysts before and after reaction, it was found that the Y₂O₃·γ-Al₂O₃ supported Ni catalysts had higher NiO reducibility, smaller Ni particle size, higher Ni dispersion and stronger basicity than those of the Ni/γ-Al₂O₃ catalysts. The analysis of catalysts after reaction showed that the addition of Y₂O₃ inhibited the Ni sintering, changed the type of coke and decreased the amount of coke on the catalysts. All the experimental results indicated that the introduction of Y₂O₃ to Ni/γ-Al₂O₃ resulted in excellent catalytic performances in autothermal reforming of methane, and Y₂O₃ played important roles in preventing metal sintering and coke deposition via controlling NiO reducibility, Ni particle size and dispersion, and basicity of catalysts.