PROCESS FOR PRODUCING ABRASION-RESISTANT SHELL CATALYSTS AND USE OF SAME

摘要

A process for producing shell catalysts, for example, for gas phase oxidations in organic chemistry from an inert support and a shell of catalyst material encompassing said support, is described. A suspension of the starting material for the shell is sprayed on a moving charge of the support while partially withdrawing the dispersing material, whereupon the crude material is dried and tempered. For this purpose the support charge is mechanically moved by a gas stream injected from below while it is loosened. The catalyst prestage containing a binder and, when required, an expanding agent is sprayed on the charge in increasing amounts from above while the ratio of dispersing agent sprayed on to dispersing agent withdrawn remains constant. The coefficient of thermal expansion of the prestage as a dry powder must not vary from that of the support by more than 15%. The applied shell is consolidated by continuing the mechanical and fluidizing mixing motion. The material is then dried in the gas, which continues to flow, and tempered, when required, after decomposing any added expanding agent.