Recycling and Application of Plastics

Plastics are used everywhere, but they also generate a lot of waste and emissions, and they are in urgent need of recycling. Currently, the tightening of sustainable development goals and the introduction of new technologies are vigorously promoting the development of plastic recycling and promoting plastic recycling to "turn waste into treasure". In the face of new business opportunities, how can plastics industry companies effectively grasp the latest trends and get a share of the pie?

Plastics emit about 2 billion tons of carbon dioxide equivalent (greenhouse gases, GHGs) every year, accounting for about 4% of total global carbon emissions. As the main plastic producer and processor, the EU accounts for 9% of global emissions. Greenhouse gas emissions occur throughout the entire plastic value chain, and only 10% of plastics are recycled after they are discarded. At the same time, plastic demand is expected to maintain strong growth, and plastic waste will also increase.

Recently, the teams of Bobby G. Sumpter of Oak Ridge National Laboratory and Guoliang Liu of Virginia Tech, as well as the team of George W. Huber of University of Wisconsin-Madison, published papers in Science magazine in the same period, discussing the issue of plastic recycling from different angles. Realize the reuse of plastic waste. Kevin M. Van Geem of Ghent University in Belgium also commented on the above two works in Science magazine and proposed the concept of circular plastic economy [2]: After raw materials are extracted from fossil fuels, they are continuously produced and processed (orange) , use, collection and classification (blue), followed by recycling and regeneration (green), forming a closed loop in which so-called "waste" is also considered a resource for further production of chemicals.

The research idea of Bobby G. Sumpter and Liu Guoliang's team is to upcycle waste polyethylene (PE), polypropylene (PP) and their mixtures into higher value surfactants [3]. PE and PP together account for nearly 60% of global plastic production (approximately 400 million tons), and their production consumes high energy.

Since mass production of plastics began in 1950 (at that time, the output was about 2 million tons), plastic output has grown at a compound annual growth rate of 8.4%, reaching approximately 348 million tons in 2017. It is estimated that 8.3 billion tons have been produced. Which can be broken down into 7.3 billion tons of resins and additives (resin plastics contain an average of 7% additives), and 1 billion tons of fiber. If this continues, Blue Earth may become a "plastic planet."

Currently, approximately 400 million tons of plastic waste are generated globally every year. But the problem is even more serious, as plastic has seeped into some of the most remote and pristine areas on Earth. Relevant research was published in Nature on July 12, 2023 at the same time, and was selected as the cover paper. Therefore, strengthening research on the recycling and upgrading of plastics has become an important proposition in the current field of polymers. Here, the editorial department has compiled the latest progress in plastic upcycling published in Nature and Science in the past year for the benefit of readers.

Therefore, strengthening research on the recycling and upgrading of plastics has become an important proposition in the current field of polymers. Here, the editorial department has compiled the latest progress in plastic upcycling published in Nature and Science in the past year for the benefit of readers.

Polyethylene + Ethylene → Propylene On September 22, 2022, John F. Hartwig’s research group at the University of California, Berkeley, developed a new polyethylene degradation process. Through a series of catalytic processes, they first introduced unsaturation into the PE chain, and then Subsequent C-C bond cleavage unwinds the carbon chain to form propylene via a combination of olefin metathesis and isomerization. The process uses a catalyst to successfully break down long polyethylene polymers into small propylene molecules. Through this process, high-density (HDPE) or low-density (LDPE) high-molecular-weight polyethylene is dehydrogenated and undergoes a metathesis reaction with ethylene to form propylene, with a yield of up to 80%. Combined with the universal application of polyethylene materials and the high efficiency of the process, this process of decomposing polyethylene into propylene has very broad application prospects. The process was published in Science in an article titled "Catalytic deconstruction of waste polyethylene with ethylene to form propylene".

Under the "Double Carbon Target" and the "Plastic Ban Order", plastic upgrading and recycling is imperative! Currently, more and more end markets (automobiles, consumer electronics, communications industries) are beginning to use recycled plastics for production and application in order to reduce emissions, reduce costs and increase efficiency.

Plastic regulations: Target setting is an effective way to promote plastic recycling

Since the 1990s, relevant mandatory regulations for plastic waste disposal have been introduced around the world, especially in Europe. Currently, about 70% of plastic waste is included in the regulatory scope of EU sustainable regulations, covering a variety of plastic application scenarios such as consumer goods and transportation goods packaging, textiles, and electronic products. But this also means that 30% of plastic waste in Europe is still not included in the scope of regulation, mainly from the construction, automobile, manufacturing and agricultural sectors. Therefore, the world is still a long way from fully realizing a circular economy, and there are many gaps in the current regulatory framework.

In 2020, 24% of plastic waste in the EU was recycled, and the rest was landfilled or incinerated. In the case of plastic packaging, the recycling rate is even higher, at 30%, because almost all of the EU's current plastic regulations focus on packaging. However, the 30% recycling rate is still far from the target set in the Packaging and Packaging Waste Directive introduced in 2018. The goal is to reach 50% recycling by 2025 and 55% by 2030

Plastic pollution has always been one of the important environmental challenges facing the world today, causing serious impacts on marine ecosystems, wildlife, and human health. According to statistics, more than 1 million bottles of plastic-packed mineral water or beverages are sold globally every minute, and sales are expected to double again by 2030. Effective plastic recycling can alleviate the impact of plastic pollution to a great extent and solve the pollution problem at the source, which has attracted extensive research by many scientists and scholars.