NU 2021-150

INVENTORS

• Tobin Marks*

• Yosi Kratish

SHORT DESCRIPTION
A solvent-free tandem catalytic process to selectively depolymerize common polyester plastics into their monomeric components, using air and moisture-stable catalysts.

BACKGROUND
A mechanism-based tandem catalytic approach enables the selective depolymerization of commodity polyester plastics such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) into terephthalic acid (or naphthalene dicarboxylic acid for PEN) and ethane (or butane for PBT), in a solvent-free process. This innovative method addresses the limitations of current PET recycling technologies, offering a promising solution for the chemical recycling of polyesters.

ABSTRACT
Combining commercially available, air and moisture-stable catalysts, Hf(OTf)4 and Pd/C, under 1 atm of H2, this technology efficiently depolymerizes laboratory grade and waste polyester plastics into their monomeric components. The process is effective on various plastics and does not require solvents, showcasing a high potential for batch and continuous-flow applications in chemical recycling.

APPLICATIONS

• Chemical recycling of commercial and post-consumer polyester plastics to monomers.

• Production of terephthalic acid and naphthalene dicarboxylic acid from PET, PBT, and PEN.

• Recovery of ethane and butane as by-products from the depolymerization process.

ADVANTAGES

• Selective production of monomers from PET, PBT, or PEN using cost-effective catalysts.

• Effectiveness with post-consumer plastics.

• Compatibility with mixed plastic types.

• Operation under mild conditions (1 atm H2) without the need for solvents.