A reusable, impurity-tolerant and noble metal-free catalyst for hydrocracking of waste polyolefins

One-step conversion of low-purity polyolefins to value-added products without pretreatments represents a great opportunity for chemical recycling of waste plastics. However, additives, contaminants, and heteroatom-linking polymers tend to be incompatible with catalysts that break down polyolefins. Here, we disclose a reusable, noble metal-free and impurity-tolerant bifunctional catalyst, MoSx-Hbeta, for hydroconversion of polyolefins into branched liquid alkanes under mild conditions. The catalyst works for a wide scope of polyolefins, including different kinds of high-molecular weight polyolefins, polyolefins mixed with various heteroatom-linking polymers, contaminated polyolefins, and postconsumer polyolefins with/without cleaning under 250? and 20 to 30 bar H-2 in 6 to 12 hours. A 96% yield of small alkanes was successfully achieved even at a temperature as low as 180?. These results demonstrate the great potentials of hydroconversion in practical use of waste plastics as a largely untapped carbon feedstock.

Automated summary

One-step conversion of low-purity polyolefins to branched liquid alkanes is achieved using a reusable, noble metal-free and impurity-tolerant bifunctional catalyst, MoSx-Hbeta. The catalyst works under mild conditions and is compatible with various types of polyolefins, including those mixed with heteroatom-linking polymers and contaminated polyolefins. The hydroconversion process demonstrates high yields of small alkanes, even at low temperatures, making it a promising method for chemical recycling of waste plastics.