The relative importance of heterogeneous and homogeneous methanol carbonylation using supported rhodium catalysts in the liquid phase

Rhodium catalysts supported on ZrO2, carbon, a cross-linked polystyrene with pendant Ph2P groups (SDT) or polyvinylpyrrolidone have been tested as catalysts for the heterogeneous carbonylation of methanol in the bulk liquid phase. In all cases, leaching of the catalyst into solution occurs and the observed increase in the rate of production of methyl ethanoate with time is attributed to the rate of the homogeneous reaction being faster than that of the heterogeneous. A detailed kinetic analysis for the catalyst supported on polyvinylpyrrolidone suggests that the rate constant for the homogeneous reaction is ca. 2 x that of the heterogeneous at 150 degrees C. (C) 1998 Elsevier Science S.A.