Sustainable Bisphenol A Alternatives from Vanillin and Erythritol Using Zeolite Catalysts

Bisphenol A (BPA), a key monomer used in polymer production, poses significant health and environmental risks, necessitating the need for sustainable alternatives. This study establishes a sustainable route for BPA alternatives via the acetalization of biomass-derived vanillin and erythritol using industrially relevant zeolite catalysts. Among various homogeneous and heterogeneous Brønsted and Lewis acid catalysts tested, heterogeneous mordenite zeolite (SiO₂/Al₂O₃ = 40) achieves the highest BPA derivative yield (90%). Kinetic studies confirm a consecutive reaction mechanism, with the hemiacetal-to-acetal step being the rate-determining step. The catalyst is recyclable and maintains stable performance over five consecutive runs. Detailed structural characterizations, reactant accessibility studies, conditional experiments, and probe molecule tests reveal that a higher external surface area, Brønsted acid sites on the external surface, and greater hydrophobicity are key to the zeolite's high efficiency. These features facilitate the adsorption and desorption of large reactant and product molecules, circumventing pore-diffusion limitations while evading byproduct water-induced deactivation. This study not only demonstrates the use of industrial zeolites for sustainable BPA derivatives from biorenewables but also highlights critical structural and compositional parameters for optimizing catalyst design. Also, the findings provide a framework for rationalizing zeolite-based catalysts for a broad range of biobased BPA alternatives.