Kinetic study on the reaction between CO₂ and tertiary amine catalyzed by zinc(II) aza-macrocyclic complexes

In this work, the kinetics study on the reaction between CO2 and tertiary amine catalyzed by zinc(II)-1,4,8,11-tetraazacyclotetradecane complexes (CM) and zinc(II)-1,4,7,10-tetraazacyclododecane complexes (CN) was carried out in a stopped-flow device. The effects of the catalyst concentration, type of tertiary amines, and temperature on the reaction rate (nu) and catalytic activity (phi) were studied. It was found that the catalyst concentration, tertiary amine with higher pK(a), and temperature had positive effects on nu. nu in N-methyl diethanolamine solution with 10.0 mol m(-3) CM and CN were 16.62 and 26.05 folds than the uncatalyzed nu at 298 K, respectively. phi increased with increasing catalyst concentration, decreasing temperature and tertiary amine's pK(a). In addition, the kinetics behavior of tertiary amine-CM/CN-CO2 systems conformed to the Michaelis-Menten model. The activation energies in catalytic systems were 4%-15% lower than that in the non-catalytic systems.