Effects of doping with CeO2 and calcination temperature on physicochemical properties of the NiO/Al2O3 system

Abstract

Abstract:The effects of doping with CeO 2 and calcination temperature on the physicochemical properties of the NiO/Al 2 O 3 system have been investigated using DTA, XRD, nitrogen adsorption measurements at -196°C and decomposition of H 2 O 2 at 30-50°C. The pure and variously doped solids were subjected to heat treatment at 300, 400, 700, 900 and 1000°C. The results revealed that the specific surface areas increased with increasing calcination temperature from 300 to 400°C and with doping of the system with CeO 2 . The pure and variously doped solids calcined at 300 and 400°C consisted of poorly crystalline NiO dispersed on γ-Al 2 O 3. Heating at 700°C resulted in formation of well crystalline NiO and γ-Al 2 O 3 phases beside CeO 2 for the doped solids. Crystalline NiAl 2 O 4 phase was formed starting from 900°C. The degree of crystallinity of NiAl 2 O 4 increased with increasing the calcination temperature from 900 to 1000°C. An opposite effect was observed upon doping with CeO 2 . The NiO/Al 2 O 3 system calcined at 300 and 400°C has catalytic activity higher than individual NiO obtained at the same calcination temperatures. The catalytic activity of NiO/Al 2 O 3 system increased, progressively, with increasing the amount of CeO 2 dopant and decreased with increasing the calcination temperature.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.