Professor Martin/Associate Researcher Wang Meng, School of Chemistry and Molecular Engineering, Peking University, recently proposed a new process for converting polylactic acid plastics into methyl methacrylate through a two-step catalytic reaction. This method has greater advantages than natural degradation paths, and has brought inspiration for the high-value conversion of other types of waste plastics. The research results were recently published in "Nature Sustainability" under the title of "Upgrading and Converting Degradable Waste Plastics to Prepare Methyl Methacrylate". The research team introduced that plastic is an important synthetic material, and its output gradually increases with the increasing development of society. By 2022, the annual output of plastic products in China has reached nearly 80 million tons. The vast majority of waste plastics are directly discarded, landfilled, or burned after use, resulting in serious environmental pollution and resource waste. Using biodegradable plastics, including polylactic acid, is a feasible solution to plastic pollution. However, the degradation rate of polylactic acid waste plastics in the actual environment is very slow, and ultimately releases in the form of carbon dioxide, resulting in a huge waste of carbon resources. Therefore, converting various biodegradable waste plastics, including polylactic acid, into high value-added chemicals is an important way to achieve carbon resource recycling. In response, the research team used molybdenum carbide based catalysts and methanol in the first step of the reaction to efficiently prepare methyl propionate from polylactic acid waste plastics through alcoholysis and hydrodeoxygenation processes without additional hydrogen. This hydrodeoxygenation catalytic system is suitable for the catalytic degradation of both polyglycolic acid and polycaprolactone. In the second step, the team used silicon oxide supported cesium lanthanum catalysts to achieve efficient conversion of methyl propionate and formaldehyde to methyl methacrylate. The efficiency of two-step conversion of poly (lactic acid) to methyl methacrylate was evaluated using a commercial poly (lactic acid) pipette. After two-step catalytic conversion of 6 grams of poly (lactic acid) pipette, 2.5 grams of methyl methacrylate and 2.1 grams of methyl propionate were obtained. It is worth noting that no additional hydrogen is required during the entire reaction process. "It can be said that using the 'carbon cycle' transformation idea to convert polylactic acid into high-value-added chemicals, a new method not only proves the feasibility of using plastic waste as a carbon resource to produce high-value products, but also may stimulate the development of upgrading and recycling processes for various waste plastics." Team members said. (Outlook New Era Network)