KINETICS STUDY ON ABSORPTION OF CARBON-DIOXIDE INTO SOLUTIONS OF ACTIVATED METHYLDIETHANOLAMINE

A disk column was used to investigate the kinetics of carbon dioxide absorption in activated methyldiethanolamine (MDEA) solutions which contain piperazine as an activator. Experiments were conducted within the temperature range 30-70-degrees-C, MEDA concentration 1.75-4.21 kmol/m3, and piperazine concentration 0.041-0.21 kmol/m3. The kinetic data agree with a proposed mechanism which can be regarded as a rapid pseudo-first-order reversible reaction between CO2 and piperazine in parallel with the reaction between CO2 and MDEA. The absorption rate can be expressed as N(CO2) = H(CO2)[D(CO2)(k2C(am) + k(p)C(p))]1/2(p(CO2) - p(CO2)*), where k2 = 5.86 x 10(6) exp(-3984/T) and k(p) = 2.98 x 10(11) exp(-6424/T).