A structure-property model for the prediction of pKa values of different amines in the CO2 capture process of concern to the prediction of thermodynamic properties

Abstract

In this study, Quantitative Structure-Property Relationship (QSPR) method has been applied on a dataset including the pKa values of 21 different structures (20 amines and ammonia) at four temperatures in the post-combustion-capture process using QSARINS. QSPR models have been accomplished in two situations, called fixed and unfixed temperatures. In the fixed temperatures, four predictive models with one descriptor have been separately developed at each temperature. Besides, thermodynamic properties have been calculated by the van’t Hoff equation using predicted pKa values. In the unfixed temperatures, two general models were developed which take into account the effects of molecular structure and temperature, simultaneously. The predicted pKa values and calculated Gibbs free energy have a good consistency with related values in the literature. The reliability of each developed model has been examined using external assessments. The values of some statistical parameters such as R2 = 0.89 and AARD% = 2.68 verify the prediction capability of models.