Infrared spectral characteristics of metal-support interactions in Ni-Silica catalysts

Abstract

The precipitation of nickel hydroxy carbonate on silica has been carried out using NiSO₄ and Na₂CO₃ under varying conditions of temperature and <em>p</em>H. Thermal and infrared studies show a shift of carbonate rich to hydroxide-rich composition as the severity of precipitation medium increases. The doublet band at 1050 and 1000 cm^-1 in the IR spectrum of silica-supported nickel catalyst is assigned to the silicate species bonded to Ni-O-C-O and Ni-O-H groups respectively. The IR spectra of samples with high CO<img src='http://www.niscair.res.in/jinfo/three.gif' border=0> / (OH) <img src='http://www.niscair.res.in/jinfo/twobytwo.gif' border=0> ratio exhibit a strong band at 1050cm^-1; this disappears more rapidly compared to the band at 1000 cm^-1 when the reduction temperature is increased from 200 to 450&deg;C. Therefore, a strong interaction between Ni(OH)₂ and silicate species is supported by infrared studies.