Analysis of Reaction Kinetics of CO₂ Absorption into a Novel 1-(2-Hydroxyethyl)-piperidine Solvent Using Stopped-Flow Technique

In this present work, the absorption kinetics of CO 2 into aqueous 1-(2-Hydroxyethyl) piperidine (1-(2-HE)PP) solutions with respect to observed pseudo-first-order rate constant ( k 0 ) and second order reaction rate constant ( k 2 ), were determined using the stopped-flow apparatus within the 1-(2-HE)PP concentration range of 0.20–1.00 kmol/m 3 and a temperature range of 293–313 K. The values of k 0 were then represented using the correlation based on the base-catalyzed hydration mechanism. The results show that the correlated values of k 0 matched well with the experimental values with an acceptable AAD of 8.3%, which indicates that the base-catalyzed hydration mechanism can satisfactorily describe the experimental kinetics data of the1-(2-HE)PP reaction with CO 2 . In order to comprehensively understand the kinetics, the ion speciation plots of 1-(2-HE)PP-H 2 O–CO 2 system were developed using the pH method. In addition, the Brønsted plots between k 2 (obtained from stopped-flow apparatus) and p K a (obtained from experimental measurement) for 1-(2-HE)PP were developed, and then used to predict k 2 using the values of p K a .