Computational Screening of Main-Group Based Heterogeneous Catalysts for Chemical Upcycling of Plastics

Abstract

The global plastic waste issue demands recycling technology development beyond the conventional ones, which is limited by contamination, polymer degradation, and energy inefficiency. The thesis describes the potential of main-group-based acid species supported on a zirconia as a catalyst for chemical upcycling of polypropylene (PP), one of the most widely used plastic but difficult to recycle. Inspired by previous study on sulfated zirconia (SZO), which abstract the hydride via its Lewis acidic site, this work explores whether the same activity can be achieved with phosphoric acid, tetraboric acid, boric acid, fluorosulfuric acid, triflic acid, and bistriflimide. Density Functional Theory (DFT) was used to determine adsorption energies, surface saturation effects, Lewis acidity (via probemolecules), and hydride abstraction barriers using Nudged Elastic Band (NEB) analysis. Fluorosulfuric acid and triflic acid were found to activate polyolefins, demonstrating their potential for catalytic upcycling. Also, fluorosulfuric and triflic acid were found to have comparable energy barriers to SZO; however no system studied surpassed SZO in terms of Lewis acidity or overall reactivity.