Chinese scientists have opened up new avenues for upgrading the recycling of discarded polyethylene plastics. Petroleum | polyethylene | plastics
Hefei, June 28th (Xinhua) - Recently, it was learned from the University of Science and Technology of China that Professor Zeng Jie's research group has made breakthrough progress in the field of plastic recycling upgrading. It is understood that researchers have designed a "hydrogen respiration" strategy to convert high-density polyethylene plastics into high-value cyclic hydrocarbons without the need for additional hydrogen or solvents, providing a new method for the "artificial carbon cycle" of waste plastics.
Schematic diagram of the degradation of high-density polyethylene plastic under the action of a catalyst.
In daily life, plastic products can be seen everywhere. However, while people enjoy the convenience brought by plastic, they also bear the negative impact of plastic pollution on the natural environment and human health. Solving the problem of "white pollution" is urgent.
Polyethylene plastic is one of the five universal plastics, with high stability and difficulty in natural degradation. Considering the similar chemical structure and composition of polyethylene and petroleum, in this research work, Zeng Jie et al. drew on the technology of the petroleum industry and treated waste polyethylene plastic as a "solid petroleum" to process and prepare petroleum based downstream chemical products.
Two processes in the petroleum industry have attracted the attention of researchers: one is the catalytic reforming of short chain gasoline fractions to obtain higher value-added cyclic hydrocarbons, which produce hydrogen gas; Another method is the hydrogenation cracking of heavy oil to prepare short chain hydrocarbons, which consumes hydrogen gas.
Inspired by these two processes, researchers have designed a "hydrogen respiration" strategy to degrade high-density polyethylene plastics. The molecular sieve supported metal ruthenium catalyst they developed can allow plastics to dehydrogenate into cyclic hydrocarbons, exhale hydrogen gas, and at the same time allow plastics to absorb the hydrogen gas released by themselves and crack into short chain hydrocarbons.
Researchers have introduced that this strategy uses the hydrogen atoms of polyethylene itself to replace the added hydrogen, achieving the "self production and self sales" of hydrogen elements, not only reducing costs, but also obtaining higher value cyclic hydrocarbon products. It is understood that cyclic hydrocarbons are an important petrochemical product that can be used as raw materials for the synthesis of drugs, dyes, resins, and fibers, with a wide range of applications.
Han Buxing, an academician of the CAS Member and a researcher of the Institute of Chemistry of the Chinese Academy of Sciences, commented: "This research work uses environmental pollutants such as waste polyethylene plastics to prepare petroleum based chemical products, provides a new method for the 'artificial carbon cycle' of waste plastics, and puts forward new ideas for the partial replacement of petroleum."
The research results were recently published in the international authoritative academic journal Nature Nanotechnology.
