Nanoparticle Surfaced-Induced Decomposition of Polyethylene to Alkylaromatics

Local surface morphology variations inherent to metal nanoparticles deterministically influence their catalytic ability to transform or deconstruct the surface-adsorbed molecules. The selectivity and yield not only depend on the facets but also on the less-coordinated defects, edges, and corners. These sites tend to stabilize molecular binding and thus promote reactions. In this study, we combined reactive molecular dynamics simulations, enhanced sampling, and first-principles density functional theory to unravel the roles of sub 3 nm Pt nanoparticle catalysts in transforming polyethylene (PE) to alkylaromatics via aromatization and hydrogenolysis. We identified a three-step mechanism that is crucial to aromatics formation, which first aligns a PE chain along a step of a suitable size, then activates successive dehydrogenation, and finally closes the ring. We further quantitatively investigated the dependence of PE deconstruction on various facet and edge types. Our study provides physical insight into the influence of non-pristine surface features on polymer deconstruction and can be used to rationally design more effective nanostructured catalysts in the future.