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

• The formation of carbamate, bicarbonate, and carbonate confirmed for MCHA and DMPD emulsion after CO2 absorption.
• Kinetics of a CO2 reaction with emulsion absorbents were measured.
• The physical properties and CO2 absorption rates of emulsion absorbent were investigated.
• Reaction rate for emulsion absorbent with CO2 were higher than alkanolamine solution.

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 323 K) and amine concentration (10, 20, 30, and 40 wt%) 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 × 107 exp(− 2458/T) and k2,DMPD = 1.002 × 106 exp(− 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.