Modeling the Effect of Cross-Link Density on Resins Catalytic Activities

Abstract

Two mathematical models were coupled to quantitatively assess the effect of cross-link density on the catalytic activity of sulfonated styrene−divinylbenzene (DVB) resins: (I) a copolymerization model comprised of the mass balances of species and sequences, which is used to quantify inaccessible catalytic sites, and (II) a second-order pseudohomogeneous kinetic model to describe the catalyzed reactions. The fraction of inaccessible sites ranged from 10% to 72% of the total sites for resins with 4% and 20% DVB, respectively. It was found that chain segments with six or less monomer units between cross-links contain inaccessible sites for the catalyzed reactions studied herein. The mathematical approach was validated with 53 catalysis experiments from the literature and provided good agreements. A linear correlation for the fraction of inaccessible sites as a function of sequences distribution was proposed and validated, providing R 2 = 0.992. These results can represent a valuable tool to improve the performance of styrene−DVB-based catalysts.