Studies on the mixed oxide catalyst MgO-SiO 2 IV. The influence of catalyst structure and texture characteristics on catalytic dealkylation of cumene

Abstract

The catalytic dealkylation of cumene was investigated on eight samples of mixed MgO-SiO 2 calcined at 600 or 800 °C. The dealkylation was found to be a first order reaction with a calculated activation energy of 8.4 kcal mol -1. The extent of cumene conversion depends almost linearly on the MgO content of the catalyst up to 85 mol.% MgO but then decreases with further increase in the MgO content. It appears that the catalytic activity does not depend on the available surface area since the catalysts heated at 800 °C, with considerably lower surface areas than the catalysts treated at 600 °C, exhibit somewhat higher activity. Hydrothermal treatment of the parent materials causes slight changes in the extent of conversion. The extent of conversion is related to the number of acidic sites per unit area as well as to the basicity of the 600 °C products; this may be due to easier cracking as a result of polarity within the surface between acidic and basic sites.