Solubilities of CO2 capture absorbents methyl benzoate, ethyl hexanoate and methyl heptanoate

摘要

Carbon capture, utilization and sequestration technology is effective for carbon emissions reduction. The development of new absorbent seems to be one of the core components of carbon capture technology. In this paper, three esters, methyl heptanoate, ethyl hexanoate and methyl benzoate, were selected to determine CO2 solubilities at different temperatures ranging from 293.15 to 333.15 K, and pressures up to 1.2 MPa, using the isothermal synthesis method. The results showed that the absorbent with the straight-chain alkyl group was more effective for improving CO2 absorption capacity than the benzene group. Ethyl hexanoate showed slightly higher CO2 solubilities than its isomer methyl heptanoate. In addition, Henry's constant and thermodynamic properties such as solution enthalpy, solution entropy, solution Gibbs energy and solution heat capacity, were determined based on the measured data since the above properties are essential for designing an absorption process. Ethyl hexanoate is superior to the other two selected absorbents, common solvents, commercial absorbents, some physical absorbents, some polymeric absorbents and some ionic liquids, which indicates that it has potential value for CO2 capture technology. However, further studies will be necessary to assess the reliability of its industrial application. (C) 2018 Elsevier Ltd.