Zhang Zhaofu, Wu Weze, Han Buxing, Jiang Tao, Wang Bo, Liu Zhimin
Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
J Phys Chem B. 2005 Aug 25;109(33):16176-9. doi: 10.1021/jp050514q.
The effect of CO2 on the phase behavior of the reaction system and equilibrium conversion for esterification of acetic acid and ethanol in ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate, [bmim][HSO4]) was studied at 60.0 degrees C up to 15 MPa. It was demonstrated that there was only one phase in the reaction system in the absence of CO2. The reaction system underwent two-phase-->three-phase-->two-phase transitions with increasing pressure. The pressure of CO2 or the phase behavior of the system affected the equilibrium conversion of the reaction markedly. As the pressure was less than 3.5 MPa, there were two phases in the system, and the equilibrium conversion increased as pressure was increased. In the pressure range of 3.5-9.5 MPa, there existed three phases, and the equilibrium conversion increased more rapidly with increasing pressure. As the pressure was higher than 9.5 MPa, the reaction system entered another two-phase region and the equilibrium conversion was nearly independent of pressure. The total equilibrium conversion was 64% without CO2 and could be as high as 80% as pressure was higher than 9.0 MPa. The apparent equilibrium constants (K(x)) in different phases were also determined, showing that the K(x) in the middle phase or top phase was much greater than that in the bottom phase.
在60.0℃至15MPa的条件下，研究了二氧化碳对离子液体（1-丁基-3-甲基咪唑硫酸氢盐，[bmim][HSO4]）中乙酸和乙醇酯化反应体系相行为及平衡转化率的影响。结果表明，在无二氧化碳时反应体系只有一相。随着压力升高，反应体系经历了两相→三相→两相的转变。二氧化碳的压力或体系的相行为对反应的平衡转化率有显著影响。当压力小于3.5MPa时，体系中有两相，平衡转化率随压力升高而增加。在3.5 - 9.5MPa的压力范围内，存在三相，平衡转化率随压力升高增加得更快。当压力高于9.5MPa时，反应体系进入另一个两相区，平衡转化率几乎与压力无关。无二氧化碳时总平衡转化率为64%，当压力高于9.0MPa时可高达80%。还测定了不同相中表观平衡常数（K(x)），结果表明中间相或顶部相中的K(x)远大于底部相中的K(x)。
