Kinetics of CO2 Absorption into Aqueous AMP/HMDA/TEG Mixtures

摘要

Mixtures of 2-amino-2-methyl-1-propanol (AMP), 1,6-hexamethyl diamine (HMDA), triethylene glycol (TEG) and water, which merge the loading capacity of AMP, reactivity of HMDA and low volatility of TEG, are improved CO2-capturing solvents. In the present study, kinetic aspects of the reaction of CO2 with the blend AMP+HMDA were investigated using co-solvents TEG+ Water. Kinetic data were experimentally obtained in a stirred cell at 303-318 K. The concentrations of AMP and HMDA in the mixtures were changed in the 2-3 and 0.1-0.5 M range whereas TEG concentration was changed between 0.7 and 2 M. Pseudofirst order rate constants were measured. Knowing the CO2 absorption rates in the aforesaid mixtures, the second-order rate constant (65195 M~(-1) s~(-1)) for the reaction between CO2 and HMDA at 308 K was found. The activation energy for the CO-(2-) HMDA system in aqueous solution was 33.1 kJ/mol. Equilibrium solubility of CO2 in AMP/HMDA/TEG/Water mixtures was measured. Finally, it was established that N,N'-dimethyl-1,6- hexamethyl diamine (or HMDAP-N,N') - a dialkyl derivative of HMDA - is a further attractive promoter for AMP in TEG+Water mixtures.