CATALYTIC COOPERATION BETWEEN MOO3 AND SB2O4 IN N-ETHYL FORMAMIDE DEHYDRATION .1. PREPARATION, CHARACTERIZATION, AND CATALYTIC RESULTS

Catalysts containing MoO3 and α-Sb2O4 with different "architectures" were prepared by different methods: mixing of separately prepared pure oxides, impregnation of MoO3 by Sb2O4 or vice versa. We report results obtained in the oxygen-aided dehydration of N-ethyl formamide catalyzed by these solids. A strong synergy between Mo and Sb is always observed. Extensive characterization of the catalysts before and after catalytic test, by X-ray diffraction, Electron Microscopy, Analytical Electron Microscope, XPS, and Ion Scattering Spectroscopy excludes the formation of mixed oxides or solid solutions as well as mutual contamination. Rather, the artificial contamination created by impregnation with a precursor of the other oxide exhibits a strong tendency to disappear. The catalytic synergy persists after the contamination has disappeared. The origin of the observed synergy is attributed to a remote control mechanism, namely spillover oxygen produced by α-Sb2O4 creates and/or regenerates active and selective sites on MoO3. © 1991.