Abstract
The surface composition of chromia–alumina catalysts has been investigated. Electron spin resonance was used to follow changes in the signal ascribed to Cr3+ ions (at g= 1.986) after reduction in dry hydrogen (Cr2+ produced) and in hydrogen + water-vapour mixture at 500°C (only Cr3+ produced). The extent of reduction to Cr2+ depends on the concentrations of chromia present on the surface. Preliminary kinetic studies show that the rate of ethane dehydrogenation is higher on Cr2+ than on Cr3+ sites. Evidence supporting the presence of Cr2+ ions on the surface has also been provided.

This publication has 0 references indexed in Scilit: