Absorption of carbon dioxide in O/W emulsion absorbent: Kinetics of absorption in N-methylcyclohexylamine and 2,6-dimethylpiperidine emulsion

Abstract

Speciation and kinetics of carbon dioxide absorption by N-methylcyclohexylamine (MCHA) and 2,6-dimethylpiperidine (DMPD) emulsion absorbents were evaluated. The physical solubility, diffusivity, and carbon dioxide absorption rate were measured as a function of temperature (293, 303, 313, and 323K) and amine concentration (10, 20, 30, and 40wt%) by using a semibatch reactor and wetted wall column (WWC). The results showed that the rate of carbon dioxide absorption by the MCHA and DMPD emulsion absorbents increased with the carbon dioxide partial pressure and amine concentration. Using the physical data and absorption rate, the rate constants for carbon dioxide absorption by MCHA and DMPD were evaluated. Based on the pseudo-first-order reaction, the rate constants were determined to be k2,MCHA=2.698×107exp(−2458/T) and k2,DMPD=1.002×106exp(−1511/T). Notably, the activation energies for carbon dioxide absorption by the emulsion absorbents containing MCHA or DMPD were lower than those of alkanolamine solutions.