LAUSR

Abstract The esterification of rosin with pentaerythritol (PE) was studied, using pressurized CO2 as an intensified additive to high-temperature water (HTW), which formed the various esters with different soften points to meet industrial applications. A multiple linear regression model was established to determine the dependence of independent variables (CO2 pressure, temperature, PE-to-rosin mass ratio and reaction time) on rosin conversion, where the elasticity of the logarithm of CO2 pressure was 0.13, indicating pressurized CO2-HTW can effectively enhance this esterification. The conversion of rosin could be improved either by increasing the PE-to-rosin mass ratio or the reaction time, but products were monoester and triesters, respectively, thus the process regulation for the formation of various esters can be achieved through operating conditions. A corresponding stepwise esterification was proposed. Furthermore, the catalytic mechanism of pressurized CO2-HWT for this esterification were identified to be the acid catalysis of carbonic acid and the enhancemennt of CO2.