Reactive Molecular Dynamics Simulations of the Depolymerization of Polyethylene Using Graphene-Oxide-Supported Platinum Nanoparticles

Abstract

While plastic materials offer many benefits to society, the slow degradation and difficulty in recycling plastics raise important environmental and sustainability concerns. Traditional recycling efforts often lead to materials with inferior properties and correspondingly lower value, making them uneconomical to recycle. Recent efforts have shown promising chemical pathways for converting plastic materials into a wide range of value-added products, feedstocks or monomers. This is commonly referred to as “chemical recycling”. Here, we use reactive molecular dynamics (MD) simulations to study the catalytic process of depolymerization of polyethylene (PE) using platinum (Pt) nanoparticles (NPs) in comparison to PE pyrolysis (thermal degradation). We apply a simple kinetic model to our MD results for the catalytic reaction rate as a function of temperature, from which we obtain the activation energy of the reaction, which shows the that the Pt NPs reduce the barrier for depolymerization. We further evaluate the molecular mass distribution of the reaction products to gain insight into the influence of the Pt NPs on reaction selectivity. Our results demonstrate the potential for the reactive MD method to help the design of recycling approaches for polymer materials.

Modeling and simulations for 2D materials: a ReaxFF perspective

“…For example, ReaxFF force fields have been developed for various nanoparticles such as Ag, Pt, Cu nanoparticles supported on graphene. Zhang et al [301] used the Pt/C/O/H ReaxFF force field [302,303] to study the catalytic effect of a single Pt nanoparticle on the decomposition of PE (figures 21(a) and (b)). The presence of a Pt nanoparticle (with or without GO support) was shown to facile the PE depolymerization by lowering the reaction activation energy, compared to simple thermal degradation.…”