Influence of alkali and rare-earth elements on the Cr(II) content and structure of Cr2O3�Al2O3MexOy catalysts

Abstract

1. Incorporation of cations of alkali elements and rare earths into aluminum-chromium catalysts after their reduction reduces the Cr(II) content in comparison with catalysts without such additives; this is due to ordering of the chromic oxide structure, leading to a decrease in the number of surface chromium ions. 2. The chemical change in the surface of oxidized aluminum-chromium catalysts after incorporation of potassium ions has little effect on the Cr(II) content. 3. The Cr(VI) ions are distributed throughout oxidized aluminum-chromium-calcium catalysts, and are not located only on the surface.