Plastic depolymerization requires a solid acid catalyst to initiate the chemical breakdown. Credit: Maskot/Getty
Scientists have developed a new way to improve solid acid catalysts, a critical tool in breaking down plastic waste, by introducing imperfections in the material’s structure1.
Plastic depolymerization requires a solid acid catalyst to start the chemical reaction. To break down large plastic polymers, the catalyst must have high acidity and large pores, to accommodate the polymer and allow it and the resulting smaller molecules to move freely. Currently, the process demands extremely high temperatures, which increases the carbon footprint, contributing to global warming.
Using defect engineering, scientists at the Tata Institute of Fundamental Research (TIFR) in Mumbai and the National High Magnetic Field Laboratory, Florida State University, in Florida in the United States created oxygen vacancies, in amorphous acidic aluminosilicates (AAS), a type of solid acid previously designed by the researchers. AAS combines the strong acidity of zeolites with the mesoporosity of amorphous aluminosilicates - types of solid acids.
The team introduced the defects in AAS through a magnesiothermic treatment, where magnesium powder at a high temperature removes oxygen atoms from its structure and produced vacancies. The material was washed with acid to remove unreacted magnesium and magnesium-based by-products.
These defect centres further enhanced the catalyst’s acidity, making it more efficient and speedy. “It reduces the energy required for tasks like plastic depolymerization. This could make plastic recycling more environmentally friendly and feasible,” says Vivek Polshettiwar at TIFR.
The researchers say that fine-tuning the defects can enable the design of specialized, high-performance catalysts for industrial production of chemicals, pharmaceuticals, and fuels.
