Capture of CO2 by vermiculite impregnated with CaO.

Abstract

Vermiculite samples were impregnated with different amounts of calcium oxide by the con- ventional thermal heating technique and subject to CO2 capture experiments in thermal

analysis equipment. The amount of CO2 captured by calcium oxide increased from 13 g of CO2 per mol of CaO to 16.8 g of CO2 per mol of CaO when the experiments were carried out with pure calcium oxide and vermiculite impregnated with CaO (1:1), respectively. Integral isoconversional methods of Kissinger-Akahira-Sunose (KAS) and Osawa-Flynn-Wall (OFW) were used for the kinetic study of the process and good correlation coefficients were achieved. The apparent activation energy values showed that for low conversions (a < 0.3)

the controlling step of the process is a mixed step where the chemical reaction and the dif- fusion of the reagents into the vermiculite have rates of the same order of magnitude

(20 kJ < Ea < 40 kJ). For higher conversions values (a > 0.3) the apparent activation energy values suggest that the slow step is a chemical step (Ea> 40 kJ).