Acetic acid and methyl acetate formation from methanol alone over ruthenium (II)-tin (II) cluster complex catalysts supported on copper-containing oxides

Abstract

Acetic acid is a very important chemical, and the carbonylation of methanol (the Monsanto process) is now one of the main processes involved in its production. Recently, we found that homogeneous Run-Sn” cluster complexes { [Ru(SnC13)5L]3-, L=CH3CN and PPh 3 are effective for the formation of } methyl acetate in a single step with methanol used as the sole source [ 11. This reaction is to be preferred over the Monsanto process because neither carbon monoxide as a carbonylation source nor iodide promoter (often corrosive to reaction apparatus) is required. However, these cluster complexes show low solubilities in methanol and conventional solvents and hence the yields of methyl acetate are rather low. In the present study, we tried to improve this advantageous characteristic by making a heterogeneous catalyst where the Run-Sn” cluster complex is supported on various inorganic supports; by performing the reaction in the gas phase, the relative amount of cluster complex in contact with methanol will be increased. Notably it was found that when copper-containing oxides (wellknown heterogeneous catalysts for methyl formate formation from methanol) were used as supports, activity and selectivity to acetic acid ( + methyl acetate) formation were remarkably enhanced.