Kinetics of the Ag/KNO3/CaCO3 Catalyzed Aerobic Propylene Epoxidation and Effects of CO2

In this contribution we investigate the aerobic propylene epoxidation over a Ag/KNO3/CaCO3 catalyst. The catalytic performance and surface speciation of the catalyst depends on the concentrations of feed modifiers such as ethyl chloride and nitric oxide, added to the feed to improve the selectivity by suppressing total combustion to CO2. After a kinetic characterization of the system, we investigate the kinetics in the presence of CO2. We demonstrate that CO2 alters the rate dependence in both reactants, affects the activation of O2, and results in the same maximum rate of propylene oxide formation. Kinetic investigation: Catalyst systems used in propylene epoxidation are often lacking thorough understanding of the system due to the complex nature of the catalyst. Improving selectivity is a key goal for the future implementation of aerobic propylene epoxidation. The catalytic performance, reaction kinetics, and surface speciation were investigated for Ag/KNO3/CaCO3 in propylene epoxidation in the presence of EtCl and NO feed modifiers. The effects of CO2 cofeeding were also examined, with added CO2 leading to higher propylene oxide selectivity.