Hydroformylation of propylene in supercritical carbon dioxide

Homogeneously catalyzed propylene hydroformylation using Co-2(CO)(8) precatalyst in supercritical carbon dioxide (SCCO2) was studied in a batch reactor. The experiments were carried out at temperatures of 66-108 degrees C and at pressures of 1350-2700 psig. The pseudo-first-order rate constant was calculated for each run employing an empirical kinetic expression from the literature. It has been observed that at constant temperature the observed rate constant increased with pressure. The activation energy of the reaction in SCCO2 was determined at 1650 and 2400 psig, and the value 23.3 +/- 1.4 kcal/mol was comparable to values of 27-35 kcal/mol obtained in conventional organic solvents. The product selectivity was determined at different temperatures and pressures, and it was observed that, at the constant temperature of 88 degrees C, the product selectivity increases from 2.7 to 4.3 as the pressure doubles from 1350 to 2700 psig.