Assessment, measurement and correlation of (vapour + liquid) equilibrium of (carbon dioxide + butyl, isobutyl, and amyl formate) systems

Abstract

In this work, three formates (butyl, isobutyl, and amyl formate) were considered as relative perfect CO2 absorption performance based on the excess Gibbs function as the thermodynamics criterion. An online static-analytical method was used to measure the (vapour + liquid) equilibrium (VLE) data for the CO2+butyl, isobutyl, and amyl formates under the pressure of (0.2 to 6)MPa and the temperatures at a range from (283.15 to 343.15)K. Then the VLE data were correlated by Peng–Robinson (PR) equation of state (EOS) with classic mixing rule, PR EOS with Wong–Sandler (WS) mixing rule and Soave–Redlich–Kwong (SRK) EOS with classic mixing rule. It is shown that SRK EOS is comparatively appropriate for CO2+butyl formate binary system. Both PR EOS with classic mixing rule and SRK EOS can be used to correlate the binary systems of CO2+isobutyl, amyl formate. It is found that the solubility order of three formates for CO2 from high to low is arranged as CO2+amyl formate>CO2+butyl formate>CO2+isobutyl formate, showing the system of CO2+amyl formate has the best absorption performance. By comparison, it indicates that formates have a greater solubility for CO2 than acetates on the condition of the same temperature and pressure. In addition, the thermophysical properties, mole absorption and mass absorptive amount of several industrial absorbents were assessed and the absorption performance of amyl formate for CO2 is better than other physical absorbents. Thus, the study concluded that amyl formate has potential research value as physical absorbent for CO2 capture.