Methanol carbonylation catalyzed over polymer-bound RhCl(CO)(PPh 3) 2: EDAX, FTIR and kinetic study

Abstract

RhCl(CO)(PPh 3) 2 was immobilized on phosphinated 2% crosslinked gel-type PS/DVB (poly(styrene-divinylbenzene) copolymer) and 20% crosslinked macroreticular-type PS/DVB. The results of EDAX study indicated that the rhodium was uniformly distributed over the polymer bead for both the macroreticular-type PS/DVB, and the gel-type PS/DVB. FTIR study indicated that the deactivation could be ascribed to the change in the structure of rhodium carbonyl from active trans-(CO)ClRhP 2 to inactive cis-(CO) 2RhClP during the methanol carbonylation (P = polymer-PPh 2).The catalytic properties of these catalysts were evaluated in the methanol carbonylation reaction. The catalytic activity of the polymer-bound rhodium component was 60–70% of its homogeneous counterpart, RhCl 3·3H 2O. However, the catalytic activity decreased after repeated use of the catalyst in methanol carbonylation due to leaching of the catalytic component from polymer bead. Modelling of the kinetics of the methanol carbonylation catalyzed over polymer-bound rhodium catalysts indicated that the rate constant and activation energy were different from those of homogeneous catalyst due to the unique properties of polymer-bound catalysts, such as swelling effect, diffusion limitation and steric hindrance.