Formation regulation of various rosin esters and intensification mechanism using pressurized CO₂

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.

Keywords:

• Various esters regulation
• pressurized CO₂–high-temperature water
• CO₂ acid catalysis mechanism
• a stepwise esterification

Disclosure statement

There are no conflicts to declare.

Additional information

Funding

This work was supported by National Natural Foundation of China (Grant Nos. 21878056, 31560241) and Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology (Grant No. 2019Z002).