NiO/La2O3-ZrO2/WO3 Catalyst Prepared by Doping ZrO2 with La2O3 and Modifying with WO3 for Acid Catalysis

Abstract

A series of catalysts, NiO/La 2 O 3 -ZrO 2 /WO 3 , for acid catalysis was prepared by the precipitation and impregnation methods. For the NiO/La 2 O 3 -ZrO 2 /WO 3 samples, no diffraction lines of nickel oxide were observed, indicating good dispersion of nickel oxide on the catalyst surface. The catalyst was amorphous to X-ray diffraction up to 300 °C of calcination temperature, but the tetragonal phase of ZrO 2 and monoclinic phase of WO 3 by the calcination temperatures from 400 °C to 700 C were observed. The role of La 2 O 3 in the catalyst was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity. The high acid strength and high acidity were responsible for the W=O bond nature of complex formed by the modification of ZrO 2 with WO 3 . For 2-propanol dehydration the catalyst calcined at 400 °C exhibited the highest catalytic activity, while for cumene dealkylation the catalyst calcined at 600 °C showed the highest catalytic activity. 25-NiO/5-La203-Zr02/15-W03 exhibited maximum catalytic activities for two reactions due to the effects of WO 3 modifying and La 2 O 3 doping.