Catalytic study of MCM-41 immobilized RhCl3 for the hydroformylation of styrene

Abstract

RhCl3 was chemically immobilized on mesoporous silicate MCM-41 functionalized by amine or phosphorus organosilane to form heterogeneous catalysts: RhCl3/MCM-41(NH2) and RhCl3/MCM- 41(PPh2). XRD and N2 adsorption-desorption studies illustrated that the functionalized MCM-41 maintained the mesoporous structural ordering, but exhibited reduced pore sizes, total pore volumes and BET surface areas. XPS characterization indicated that chemical interaction between rhodium species of RhCl3 and the surface ligands occurred, and rhodium (III) species were reduced to lower oxidation states. RhCl3/MCM-41(NH 2) was tested to be stable for recycling, however a significant rhodium leakage was observed for RhCl3/MCM-41(PPh2). The catalytic system formed of the prepared RhCl3/MCM-41(NH2) catalyst and additional PPh3 (PPh3/Rh = 2.5) showed very good catalytic activity and high selectivity toward the branched aldehydes in the hydroformylation of styrene. © 2008 Springer Science+Business Media, LLC.