Study on CO2 Sorption on Coal Measured by Heat of Sorption and Spin-Spin Relaxation

Abstract

CO2 sorption on coal was estd. by two expts., one is heat of sorption measurement and the other is 1H-NMR measurement. In the heat of sorption measurement, differential heat of sorption (qd) was compared with the calcd. one. Measured qd was same value with calcd. one at low pressure. It decreased gradually with pressure and became lower than the calcd. one. Since it couldn't be explained by the theory based on physisorption, it is estd. that the coal-CO2 system could not be explained by only simple physisorption. In 1H-NMR measurement, spin-spin relaxation time (T2) and compn. fractions of L12, L2 and G were measured. Compn. fractions and T2 of L1 increased with CO2 gas pressure. Furthermore, the correlation was obsd. between vol. increments and dissoln. amt. at over 10 atm. It indicates that part of CO2 sorption capacity was used to coal relaxation