Kinetics of the carbon monoxide reactive uptake by an imidazolium chlorocuprate(I) ionic liquid

• The kinetics of CO reaction with a chlorocuprate(I)-based ionic liquid are reported.
• Enhancement factors varied with temperature and Cu(I) concentration between 2 and 7.
• Kinetic reaction is first order in CO and first order in Cu(I).
• Second order kinetic constant of reaction and the activation energy are determined.

In this work, the kinetics of a new process for the selective recovery of CO from industrial flue gases based on the reactive absorption of carbon monoxide in a chlorocuprate(I) ionic liquid have been assessed; the experimental analysis has been performed in a stirred tank reactor at temperatures ranging from 293 to 313 K and copper(I) concentrations from 0 to 2 kmol m−3. To the best of our knowledge, this is the first study on the kinetics of CO reactive uptake in ionic liquid media, since only kinetic data of CO reactive absorption in COSORB solutions have been previously reported. The enhancement factors obtained from the experimental CO absorption fluxes varied from 2.1 to 6.8; however, the infinite enhancement factors were not achieved at any operating condition so the instantaneous kinetic regime was not met. Therefore, the kinetic results, apparently obtained in the fast reaction regime, were interpreted both from a point of view of pseudo-first order reaction and using the DeCoursey approximation based on the Danckwerts surface-renewal model with an enhancement factor corrected for reversible reactions of finite rate. The overall pseudo-first order kinetic constants obtained with both approaches are very similar, indicating that the reaction very likely took place in the pseudo-first order reaction regime. Besides, the reaction rate could be interpreted in terms of first order in both reactants, thus the second-order forward rate constant at 303 K and the activation energy found for this reaction are 2.5 × 10−4 m3 mol−1 s−1 and 23.7 kJ mol−1, respectively.