Recycling: Loop/Hyosung TNC tie-up to expand polyester recycling; Yale researchers develop catalyst-free pyrolysis with 66% yield to convert waste into fuel

Canada’s Loop Industries and Hyosung TNC, a sustainable textile solutions provider, have tied up to expand access to circular polyester through textile-to-textile supply chains.

This alliance combines Loop’s Infinite Loop depolymerisation technology and Hyosung TNC’s expertise in advanced textile materials. Loop transforms low-value textile waste into Twist, its branded polyester resin that is 100% recycled, fully traceable, and specifically designed for the textile industry. Hyosung TNC then converts this material into performance yarns under its regen brand portfolio, for brands across fashion, activewear, and other textile markets.

The result is a circular solution that meets the technical and environmental needs of today’s leading global brands. This relationship has been established for products from Loop’s Terrebonne facility and will be significantly expanded once the planned India Infinite Loop facility is operational.

Hyosung TNC’s customer base spans Asian, Europe and North America.

“Building on the success of our collaboration with brand partner, Pleatsmama, where we introduced a limited-edition handbag made entirely from textile-to-textile recycled polyester, we’re proud to deepen our strategic alliance with Loop Industries,” said Simon Whitmarsh-Knight, Hyosung TNC Global Sustainability Director – Textiles.

Meanwhile, as tonnes of plastic waste continue to build up in landfills every day, Yale University researchers have developed a way to convert this waste into fuels and other valuable products efficiently and cheaply. The results of their work are published in Nature Chemical Engineering.

Specifically, the researchers are using a method known as pyrolysis, a process of using heat in the absence of oxygen to molecularly break materials down. In this case, it’s used to break plastics down to the components that produce fuels and other products. The study was led by Yale Engineering professors Liangbing Hu and Shu Hu, both members of the Center for Materials Innovation and Yale Energy Sciences Institute.

Conventional methods of pyrolysis often use a catalyst to speed up the chemical reactions and achieve a high yield, but it’s a method that comes with significant limitations. 

“Whenever you talk about catalysts, they’re very expensive and you have a lifetime issue because catalysts will eventually die by different means,” said Liangbing Hu, the Carol and Douglas Melamed Professor of Electrical & Computer Engineering & Materials Science, and director of Center for Materials Innovation.

Methods that don’t employ a catalyst, though, tend to have low rates of converting the waste into products of use. 

For this project, the researchers found a way around both of these obstacles and developed a highly selective, energy-efficient, and catalyst-free pyrolysis method that can convert plastic into valuable chemicals.

The key, they say, is a 3D-printed electrically heated carbon column reactor made of three sections of decreasing pore size. The first section is made of one-mm pores, while the next section contains 500-micrometer pores, and the third section is made of 200-nanometer pores. As the chemicals pass through the reactor, the hierarchical porous structure plays a pivotal role in controlling the reaction progress of the chemicals. For one thing, it prevents larger molecules from advancing through the reactor before they’ve been adequately broken down.

Further, it provides a way to control the temperature in the reactor, which prevents coking and other effects that can inhibit the process. 

To test the system, the researchers tried the reactor out on a sample of PE and reported a record-high yield of nearly 66% of the plastic waste converted into chemicals that can be used for fuels. 

Using 3D printing to build the structure allowed the researchers to precisely control the dimensions of the reactor pores and investigate the effects of pyrolysis.

To demonstrate a more scalable design, the researchers also used a device made up of commercially available carbon felt. They found that this design - even without the optimisation that a 3D-printed structure provided - still improved the selectivity of the pyrolysis products and achieved a satisfactory yield, converting more than 56% of the plastic into useful chemicals.

This work was done through collaborations with Prof. Qi Dong of Purdue University, Profs. Kelvin Fu and Dongxia Liu of the University of Delaware, Prof. Jie Huang of Missouri University of Science and Technology, Prof. Fernando V. Lima of West Virginia University, Prof. Xuejun Pan of the University of Wisconsin–Madison, Prof. Yiguang Ju of Princeton University, and Dr. Gregg Beckham of National Renewable Energy Laboratory and Bottle Consortium.

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