The global plastic waste crisis has been burgeoning for decades due to inadequate processing of post-consumer plastic. Traditional recycling methods have been unable to uptake the > 300 million tons of plastic waste produced annually, largely leading to plastic being thrown into landfills and the environment. Furthermore, plastic production is projected to only increase as construction, shipping, and consumer applications continue to expand. Ultimately, this has led to an abundance of microplastics in the food chain, in our waterways, and in our bodies that will continue to grow. The work we have conducted aims to circumvent the current stream of plastic waste by converting it into higher value products, such as waxes, detergents, and lubricants in particular. We have designed a catalyst composed of ~2 nm Pt nanoparticles decorating 50 – 70 nm SrTiO₃ nanocubes (Pt/STO) that convert polyethylene (PE) and polypropylene (PP) of varying molecular weight (M_w = 4 – 900 kDa) and structure (HDPE, LLDPE, iPP, sPP, aPP, etc.) into wax and liquid C₃₀ – C₄₀ products. Cube-on-cube epitaxy prevents sintering of the Pt nanoparticles during 300 °C and 170 psi H₂ batch reaction conditions. The resulting liquid products have been tribologically evaluated and found to perform comparably to high-end synthetic base oils, such as polyalphaolefins (PAOs). A 44% reduction in wear was also observed when compared to traditional Group III mineral oil. Blending these plastic-derived oils with synthetic oils also offered a synergistic reduction in wear when compared to standalone oils, hinting at an ease in market implementation with existing oil formulations. Explorations on analogous catalyst architectures using alternative metals are currently underway in attempts to improve reaction kinetics while maintaining the high yields to liquid product (99%) from Pt/STO. Testing of post-consumer mixed plastic feedstock with various contaminants and additives is also being done to ensure commercial viability of this catalytic technology at scale to effectively combat the plastic crisis.

Shishir Kumar

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