Dehydrogenation of methanol to methyl formate over copper-containing perovskite-type oxides

Abstract

The dehydrogenation of methanol over partially substituted copper-containing LaM 1-xCu xO 3 (M=Mn,Ti) oxides has been studied. At atmospheric pressure and temperatures in the range 200–260°C methyl formate was the major reaction product with selectivity ca. 65%, carbon monoxide and small amounts of dimethyl ether and methane also being observed. In general, both activity and selectivity were found to be stable, without any apparent deactivation after two hours on-stream. The pre-reduction of the two catalyst series at temperatures in the range 200–450°C modified neither the specific activity nor the methyl formate selectivity. The X-ray photoelectron spectra of the catalyst used in the reaction revealed that reduced copper species are responsible for the catalytic activity. The L 3M 4, 5M 4, 5 Auger copper transition at 1850.9 eV found on the representative LaMn 0. 4Cu O. 60 3 prereduced and used catalyst confirmed that the dominant reduced copper species is metallic copper. In addition, although copper is highly stable in the perovskite structure, some migration of copper from the subsurface layers toward the topmost layer seems to occur on catalysts prereduced and/or used in the reaction.