Eco-friendly nitration of acetanilide over MCM-41-supported CeCuCoOx catalyst: A solid acidic catalysis strategy

Abstract

The development of solid acidic catalyst is of great significance to the safe, controllable, efficient and environment-friendly nitration of aromatics. Herein, a series of trimetallic supported catalysts were obtained by the equivalent-volumetic impregnation method. In the as-prepared Ce4Cu6Co0.5Ox/MCM-41 catalyst with strong acidic sites, the metal oxide particles mainly distributed in a form of nanowires in MCM-41 molecular sieve channels. And, the Ce4Cu6Co0.5Ox/MCM-41 catalyst exhibited an excellent catalytic performance for the nitration of acetanilide with equivalent dilute nitric acid as a nitration reagent. Surprisingly, 91% conversion of acetanilide with 91.6% selectivity to mono-nitroacetanilide was achieved. The nitration of acetanilide obviously exhibited a typical ortho-para nitration effect of the aromatics. Furthermore, an excellent stability and acceptable reusability proved a potential to replace the nitration system of concentrated acid in chemical industry. The Lewis acid sites of Ce4Cu6Co0.5Ox/MCM-41 solid acid catalyst can act a similar role to a strong protic acid in mixed acid system, which can polarize nitric acid molecules to form active NO2+ reagents. Meanwhile, the abundant strong acidic sites of solid acidic Ce4Cu6Co0.5Ox in MCM-41 channels are significantly conducive to the sorption and activation of the reactants. The present work provides a prospective strategy for constructing a solidic acid catalyst with an eco-friendly nitration of aromatics.