Resin-catalyzed reaction modeling integrating catalyst swelling and sites accessibility: Application to solketal synthesis

A novel mathematical model for resin-catalyzed reactions, incorporating dynamic variations in the resin's swelling index, internal mass transfer resistances, non-ideal liquid mixtures, and limited site accessibility, was developed. The Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism, considering water adsorption, was used. Validation with experimental solketal synthesis data in ethanol (R² = 0.96) and solventless systems (R² = 0.99) was successful. A copolymerization model estimated the resin's swelling and accessibility features, using Karam and Tien’s algorithm to obtain linear swelling data correlated with glycerol conversion (R² = 0.9995). Incorporating these linear equations into the catalysis model indicated glycerol conversion could be up to four times higher than in unswollen systems due to increased porosity and decreased tortuosity. Gibbs free energies of 4.7 ± 0.9 kJ mol⁻¹ (solvent) and 12.1 ± 0.6 kJ mol⁻¹ (solventless) were found, with a reaction rate constant of 109 s⁻¹ at 313 K on the catalytic sites.