EFFECTS OF RARE EARTH OXIDES ON PERFORMANCES OF Ni/Al_2O_3 CATALYSTS FOR METHANE STEAM REFORMING REACTION

The Catalytic performances for methane steam reforming reaction ofNi/Al_2O_3(commercial), Ni/Al_2O_3 (developed surface )and Ni/Al_2O_3-R_xO_y (R israre earth oxide) Catalysts were investigated by means of X-ray diffraction,TG, SEM/ X-ray analysis, pulse gas chromatography,BET and Mercuryporsiniter techniques. The distribution of rear earth oxides on the supports,themetal-support (additives) interaction and the influence of rare earth oxideadditives on the dispersion of active components,catulytic activities,variationof nickel crystallites size,CO chemisorption,formation of NiAl_2O_4 as well asthe reducibility of the catalysts were examined.The presence of rare earthoxides in the Ni/Al_2O_3 (developed surface) results in great improvement ofstubility through suppressing the growth of Ni crystallites,the oxidation of themetallic Ni and the formation of NiAl_2O_4. The effect of heavy rare earth oxidesis more distinct than that of the light ones.Strong metal support interaction(SMSI) exists in Ni/Al_2O_3- R

EFFECTS OF RARE EARTH OXIDES ON PERFORMANCES OF Ni/A1_2O_3CATALYSTS FOR METHANE STEAM REFORMING REACTION

The catalytic performances for methane steam reforming reaction ofNi/Al2O3 (commercial) ,Ni/Al2O3(developed surface)and Ni/Al2O3-RxOy(R is rare earth oxide) catalysts were investigated by means of X-ray diffraction, TG, SEM/ X- ray analysis, pulse gas chromatography, BET and Mercury porsiniter techniques. The distribution of rear earth oxides on the supports, the metal-support (additives) interaction and the influence of rare earth oxide additives on the dispersion of active components, catalytic activities, variation of nickel crystallites size, CO chemisorption, formation of NiAl2O4 as well as the reducibility of the catalysts were examined. The presence of rare earth oxides in the Ni/Al2O3 (developed surf ace) results in great improvement of stability through suppressing the growth of Ni crystallites, the oxidation of the metallic Ni and the formation of NiAl2O4. The effect of heavy rare earth oxides is more distinct than that of the light ones. Strong metal support interaction (SMSI) exists in Ni/ A12O3- RxOy catalyst, and it may be the result of interactions that made the performances of catalysts greatly improved. And the model of interaction is different from the catalyst doped with Y2O3 or La2O3 to the catalyst doped with CeO2. In Ni/A12O3-La2O3 and Ni/A12O3-Y2O3, the interaction may mainly be the embedment, but in Ni/Al2O3-CeO2,it may be an electronic interaction.