Valorization of waste biodegradable polyester for methyl methacrylate production

Biodegradation of polyesters such as polylactic acid (PLA), which could serve as a carbon source for value-added chemicals, leads to CO2 emissions. Here the authors develop a two-step catalytic process to convert PLA into methyl methacrylate, a key building-block molecule, for sustainable valorization of waste PLA. Biodegradable polyesters such as polylactic acid are promising alternatives to conventional plastics as they do not accumulate in the environment upon disposal. However, their biodegradation leads to CO2 emissions. Alternatively, waste biodegradable polyesters could serve as a carbon source for the production of value-added chemicals. Valorization of waste biodegradable polyesters not only avoids CO2 emissions during their biodegradation but also achieves sustainable carbon use. Here, we report a two-step catalytic process to convert polylactic acid waste into methyl methacrylate, a key building-block molecule. Polylactic acid is first transformed into methyl propionate with near-quantitative yields (conversion >99%, selectivity 98%) over the alpha-MoC catalyst in methanol solution, which is followed by reacting the obtained methyl propionate with formaldehyde to produce methyl methacrylate with a conversion of 81% and selectivity of 90%. This study opens up a new path for managing end-of-life biodegradable polyester plastics and contributing to a circular economy.