Infrared study of hydroxyl groups on nickel oxide and silica‐supported nickel catalysts

Abstract

AbstractThe decomposition of nickel hydroxide and the decomposition and reduction of some silica supported catalysts have been studied by means of IR spectroscopy.In the spectrum of decomposed nickel hydroxide two bands remain at 3676 and 3575 cm−1 which may be assigned to the existence of free and disturbed hydroxyl groups on the nickel oxide surface. The presence of these groups only partially explains the previously published water retention after decomposition. The band at 3676 cm−1 also remains in the spectrum of a silica‐supported nickel impregnation catalyst after heat treatment and disappears readily after reduction with hydrogen. IR absorption bands at other positions in other types of supported nickel catalysts possibly originate from the formation of nickel hydrosilicates.The decomposition of nickel hydroxide was also studied by means of thermogravimetry and it was found that the rate of decomposition at 225°C could be described by a first order law, provided that the degree of conversion was defined as being one at the apparent decomposition stage of about 80%.