Homogeneously catalytic hydroformylation of propylene in supercritical carbon dioxide

This project focuses on pollution prevention in chemical process industries by replacing organic solvents used in homogeneous catalysis reactions with environmentally friendly solvents.; In this study, supercritical carbon dioxide was used as the reaction medium to replace the conventional organic solvents. The homogeneously catalyzed propylene hydroformylation using Co-based and Ru-based catalysts in supercritical carbon dioxide was studied in a batch reactor. The experiments were carried out at the temperature range of 68 to 108{dollar}spcirc{dollar}C and the operating pressure was changed from 90.6 to 194.1 bar. Different feed concentrations of reactants and different amounts of catalyst per batch were used. An empirical kinetic expression was evaluated and the rate constant and the activation energy were determined. The product selectivity was also determined at different reaction conditions. A visual cell was fabricated and used to monitor the phase behavior of the reaction mixture. All the reactions were carried out in the single-phase region. At a constant temperature, the selectivity increased with pressure. At a given pressure, the selectivity decreased with temperature. By equilibrium calculations it was shown that the changes in selectivity were not equilibrium controlled. The transition-state theory was employed to interpret the observation. The partial molar volumes of the two products were measured using the dynamic tracer response technique. The difference of the partial molar volumes of two isomers was related to the selectivity variation at constant temperature. The Peng-Robinson EOS was employed along with the van der Waals I-fluid mixing rules to calculate the partial molar enthalpies. The interaction parameters were obtained from the partial molar volume data. The partial molar enthalpy data were used to explain the selectivity change with the temperature at a constant pressure.