CHEMICAL EQUILIBRIA OF ABSORPTION OF C02 INTO NONAQUEOUS SOLUTION OF AMINE

抄録

The moles of CO₂ absorbed into an amine-nonaqueous solvent mixture were measured by using the stirred-cell method. The test solutions were the mixtures of amine such as butylamine, tert-butylamine, dibutylamine, diethylamine and dipropylamine, and solvents such as octane, triethylamine and methanol.
The equilibria of the reactions between CO₂ and amine in nonaqueous solvent were studied by examining the pressure dependency of the absorption of CO₂ at lower temperatures, and could be described by the following reactions:
CO₂(1)+R₂NH⇔R₂NCO₂H (1)
R₂NCO₂H+R₂NH⇔R₂NCO₂^-R₂NH₂⁺ (2)
R₂NCO₂H+R₂NH⇔R₂NCO₂^-+R₂NH₂⁺ (3)
where R is the alkyl group.
The equilibrium constants, K₁, K₂ and K₃, were estimated simultaneously by the method of least squares with respect to the pressure dependency of the absorption of CO₂.
The equilibria of the reactions in a nonpolar solvent were mainly described by Eqs. (1) and (2). Those in a polar solvent were described by Eqs. (1) and (3). The proposed reactions, Eqs. (1) to (3), were supported by enthalpies estimated from the Arrhenius plot of the equilibrium constant.