A promising dual-functionalized MIL-101 catalyst for Bisphenol A synthesis: A theoretical study

The production of bisphenol A from phenol and acetone is a typical reaction that requires the synergistic catalysis of both sulfonic acid and thiol groups. However, although the roles of the two groups play in the reaction have been inferred based on macroscopic phenomena, it has not been proved by any systematic theoretical investigation. Metal Organic Frameworks (MOFs), as excellent carriers that can be modified by multi-functional groups, could be the ideal catalysts for bisphenol A production through rational design. Herein, we investigate the overall mechanism of this reaction using density functional theory (DFT) calculations. We find that the existence of thiol group facilitates the adsorption and activation of acetone carbocation and allylphenol carbocation on sulfonic acid-type MOFs. Kinetic simulation techniques were employed to investigate the selectivity at different temperatures. Specifically, it was found that the formation of the allylphenol carbocation is the rate-determining step. The intermediate species (CH3)2C(C6H4OH)* is the dominant intermediate in form (I) at all temperatures, and high temperature accelerate conversion of (CH3)2C(C6H4OH)*(I) to BPA. The energy barrier difference between the (CH3)2C(C6H4OH)*(I) and phenol to generate bisphenol A and 2,4-bisphenol A is-0.53 eV, making it easier to generate bisphenol A. The results provide theoretical guidance for the development of MOFs catalysts for bisphenol A synthesis.