ACTIVITY AND SURFACE CHARACTERISTICS OF SEVERAL ALKALI-DOPED IRON CATALYSTS FOR NITRILE HYDROGENATION

A non-doped and several alkali (Na, K, Cs)-doped iron catalysts were prepared by reduction of the impregnated iron oxide. The surface characterization of the catalysts was accomplished by use of BET, XRD, XPS, and surface acid determination. The surface areas of the catalysts decrease with the increase of the alkali atomic volume (BET). Alkali migration towards the surface is always found (XPS). The surface acid determination shows an increase in the number of acid centres per m2 of catalyst with the atomic volume of the alkali promoter. The curves of base adsorption show the presence of acid sites of different strengths in all the reduced catalysts. The characterization results are correlated with those of catalytic activity for hydrogenation of adiponitrile at 200-250 °C. The results indicate correlations between conversion and the type and concentration of surface acid sites. © 1990.