In 2019, the world produced 353 million tons of plastic waste. Of this, a mere 9% underwent recycling processes, with 19% being burned, and 22% escaping into the natural environment due to improper handling. The bulk of the remaining plastic waste was deposited in landfills, presenting a significant risk to environmental safety and human health. Plastic wastes are rich in energy and carbon, presenting a potential resource for the chemical industry. Initiatives are underway to convert these wastes into valuable chemicals through a process known as chemical upcycling. Our studies indicate that zirconia nanoparticles, which are abundant on Earth, can effectively break down the carbon-carbon bonds in polyethylene, leading to the production of small hydrocarbon molecules with a narrow distribution. These reactions are facilitated by a material composed of zirconia nanoparticles encased within the structure of mesoporous silica, referred to as L-ZrO₂@mSiO₂. The mesoporous silica (mSiO₂) coating plays a crucial role in stabilizing the active sites required for the catalytic process. Our density functional theory (DFT) analyses suggest that these oxides can perform hydrogenolysis of C–C bonds with an efficiency that rivals that of commercial Pt/C, thanks to the unique combination of small ZrO₂ crystals and mSiO₂ which likely hosts numerous ZrO_x defects with catalytic properties. We propose a novel bifunctional (hydroxy)organozirconium oxide species for catalytic applications. The hydrogenolysis process involving L-ZrO₂@mSiO₂ represents an innovative heterogeneous counterpart to the C–C bond cleavage processes demonstrated in surface organometallic chemistry (SOMC). Additionally, L-ZrO₂@mSiO₂ has a much better tolerance to oxygen and moisture than SOMC catalysts and thus can be readily adopted by industry.

Kyung-Eun You

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