(638f) Computational Design of Highly Selective Catalyst for PET to BTX Production Via Hydrogenolysis

The conversion of waste plastics into energy-dense chemical feedstocks such as benzene, toluene, and xylene (BTX) offers a promising route to address both environmental challenges and energy demands. As BTX compounds are key components in fuel blending and chemical manufacturing, efficient catalytic processes for their production from plastic waste are of great interest. In particular, selective hydrogenolysis of polyethylene terephthalate (PET)-derived intermediates provides a viable path for chemical upcycling and energy recovery. In this study, density functional theory (DFT) calculations were employed to investigate the hydrogenolysis mechanisms of Bis(2-hydroxyethyl) terephthalate (BHET) to BTX over Pt/Sn alloy catalysts.

Our computational analysis of the hydrogenolysis mechanism from BHET to xylene revealed that the reaction steps involve the elimination of two water and two ethylene glycol molecules, necessitating the dissociative adsorption of six hydrogen molecules. DFT results indicate that on Pt₃Sn catalyst, the Sn sites exhibit strong adsorption of the carbonyl group, which facilitates C–O bond activation and subsequent cleavage, thereby promoting the overall hydrogenolysis process. Pt site also demonstrates superior dissociative hydrogen adsorption capability, particularly under high hydrogen coverage, providing a consistent supply of active hydrogen atoms required for the reaction. Moreover, the study delved into the roles of metal-support interactions, particularly focusing on how the Pt/Sn catalyst interacts with the Al₂O₃ support. It was observed that these interactions influence the dispersion of the metal sites and the accessibility of reactant molecules, impacting the catalyst's activity and selectivity.

The insights garnered from these analyses suggest the potential of using Pt/Sn alloys in developing next-generation catalysts that not only improve the selectivity towards BTX but also reduce the energy requirements for PET recycling.