Direct Conversion of Polypropylene into Liquid Hydrocarbons on Carbon-Supported Platinum Catalysts

Efforts to selectively convert polypropylene (approximate to 30 % of all plastic waste) have not been particularly successful. Typical distributions span from gas to solid products, highlighting a challenging cleavage control. Here, carbon-supported platinum nanoparticles were designed for complete hydrocracking into liquid hydrocarbons (C-5-C-45). The metal and carrier phases operated synergistically. The cleavage activity depended on platinum and its rate rose with decreasing particle size. The carbon carrier controlled selectivity via hydrocarbon binding strength, which depended on the chain length and on the surface oxygen concentration. An optimal binding provided by carbons with high oxygen content promoted both adsorption of long chains and desorption of short products. This strategy achieved an unprecedented 80 % selectivity toward motor oil (C-21-C-45). Carbons exhibiting too strong binding (low oxygen content) hindered product desorption, while non-binding materials (e. g., silica or alumina) did not promote plastic-Pt contact, leading in both cases to low performance. This work pioneers design guidelines in a key process towards a sustainable plastic economy.

Automated summary

The study successfully converted polypropylene into liquid hydrocarbons with up to 80% selectivity for motor oil using carbon-supported platinum nanoparticles. It was found that the selectivity was controlled by the binding strength of hydrocarbon on the carbon carrier, with an optimal effect seen in carbons with high oxygen content.