A Frugal High-Throughput Method for Poly(ethylene terephthalate) Depolymerisation and Polymer-Supported Metal Catalyst Discovery

To address the critical issue of plastic waste, new methods for depolymerising plastics such as poly(ethylene terephthalate) (PET) must be developed. Existing methods are limited by the high temperatures and pressures used, as well as issues around catalyst robustness and selectivity. To overcome these issues, highly active catalysts must be discovered and developed, necessitating thousands of individual reactions. Unfortunately, existing methods for PET depolymerisation are limited by the need to weigh out multiple solid species per reaction, the insolubility of many of these species, the high temperatures and pressures used (frequently ≥ 180 °C), and the timeconsuming nature of many analysis techniques. In this work we develop a broadly applicable highthroughput process for PET depolymerisation that rapidly accelerates the rate of catalyst discovery by enabling one researcher to conduct ca. 100 × 2 h reactions per day using readily available equipment. We demonstrate the potential of this methodology by using it to explore polymersupported metal catalysts for PET depolymerisation, conducting > 630 individual reactions to map out this chemical space in a catalyst-agnostic fashion that includes examples of heterogeneous, homogeneous, gel-like, and colloidal systems. The depolymerisation activity of top-performing catalysts was examined against a panel of commodity polymers to generate selectivity profiles, demonstrating the broad scope of this methodology outside of PET depolymerisation. This methodology will accelerate the discovery and development of new depolymerisation catalysts, democratise and standardise depolymerisation methodologies, and generate large datasets for future machine learning approaches to digital catalyst discovery.