Structure and Activity of NiO/α-Al_2O_3 and NiO/ZrO_2 Calcined at High Temperatures I. Structure

Abstract

A series of NiO/α-Al_2O_3 and NiO/ZrO_2 catalysts were prepared by impregnation and calcination in air between 750 and 1050 °C. Examination of the catalysts by means of nitrogen adsorption, H_2 chemisorption, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy showed marked variations in physical and chemical properties as a function of calcination temperature. The results indicate that NiO does not interact with ZrO_2 whereas NiO-Al_2O_3 interaction is extensive at the interface between NiO and Al_2O_3 when the calcination temperature exceeds 850 °C. When the calcined samples of NiO/ZrO_2 were reduced in hydrogen, extensive redispersion of the metal was observed.

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