Scalable Synthesis of Pt/SrTiO3 Hydrogenolysis Catalysts in Pursuit of Manufacturing-Relevant Waste Plastic Solutions

An improved hydrothermal synthesis of shape-controlled, size-controlled 60 nin SrTiO3 nanocuboid (STO NC) supports, which facilitates the scalable creation of platinum nanoparticle catalysts supported on STO (Pt/STO) for the chemical conversion of waste polyolefins, is reported herein. This synthetic method (1) establishes that STO nucleation prior to the hydrothermal treatment favors nanocuboid formation, (2) produces STO NC supports with average sizes ranging from 25 to 80 nm with narrow size distributions, and (3) demonstrates how SrCO3 formation and variation in solution pH prevent the formation of STO NCs. The STO synthesis was scaled-up and conducted in a 4 L batch reactor, resulting in STO NCs of comparable size and morphology (m = 22.5 g, d(avg) = 58.6 +/- 16.2 nm) to those synthesized under standard hydrothermal conditions in a lab-scale 125 mL autoclave reactor. Size-controlled STO NCs, ranging in roughly 10 nm increments from 25 to 80 nm, were used to support Pt deposited through strong electrostatic adsorption (SEA), a practical and scalable solution-based method. Using SEA techniques and an STO support with an average size of 39.3 +/- 6.3 nm, a Pt/STO catalyst with 3.6 wt % Pt was produced and used for highdensity polyethylene hydrogenolysis under previously reported conditions (170 psi H-2, 300 degrees C, 96 h; final product: M-w = 2400, D = 1.03). As a well-established model system for studying the behavior of heterogeneous catalysts and their supports, the Pt/STO system detailed in this work presents a unique opportunity to simultaneously convert waste plastic into commercially viable products while gaining insight into how scalable inorganic synthesis can support transformative manufacturing.

Automated summary

An improved hydrothermal synthesis method for shape-controlled and size-controlled STO NC supports was reported, enabling the scalable creation of Pt/STO catalysts for chemical conversion of waste polyolefins. The study demonstrated the importance of STO nucleation, SrCO3 formation, and solution pH in determining the formation of STO NCs. The Pt/STO catalyst produced through strong electrostatic adsorption showed promising results in high-density polyethylene hydrogenolysis.