Path to plastics recycling lies in the chemical route

17:09 PM | November 8, 2019 | Francinia Protti-Alvarez

Renewed interest in recycling is pushing R&D in chemical recycling process technologies, which could hold the key to increasing the volumes recycled.  Polyethylene terephthalate (PET) has the greatest potential to be recycled.

Eastman is investigating building a commercial plant for its advanced circular recycling technology that was shelved in the 1990s.

Nearly all the PET recycled today is done mechanically. Around the world, albeit to varying levels, the infrastructure for post-consumer PET collection is already in place. According to IHS Markit data, the average PET collection rate in 2017 was 55% worldwide.

Chemical recycling has the potential for endless closed-loop recycling. Theoretically, chemical processes can take larger amounts of poorer quality post-consumer PET and transform it into feedstock to produce virgin PET resin.

However, only a portion of the post-consumer PET collected becomes recycled PET (rPET). The rest is disposed of, typically because of contamination or poor quality. Most of the rPET goes into fiber applications, particularly staple fiber, which have less stringent requirements than packaging resins such as bottle-grade PET, IHS Markit says.

Start-ups working on chemical-recycling platforms say these would be able to convert mixed post-consumer PET waste, including colored resin, into high-quality feedstock.

Loop Industries’ (Terrebonne, Quebec, Canada) platform relies on ambient temperature and pressure for depolymerization, while Carbios’s (St-Beauzire, France) process aims for enzymatic depolymerization. Meanwhile, Ioniqa Technologies’ (Eindhoven, Netherlands) depolymerization platform uses an ionic liquid catalyst to achieve its goal, and Gr3n (Castagnola, Switzerland) is putting on trial its depolymerization process using microwaves.

“Patents disclosure from these companies indicates that the technologies are still many years from commercialization. However, these technologies could potentially support a circular supply chain,” says Susan Bell, research and analysis director at IHS Markit.

There are several commercially proven chemical-recycling processes: Uhde Inventa-Fischer’s Flake-to-Resin (FTR) process ; Sabic’s post-consumer PET upcycle process; and Equipolymers’ (Schkopau, Germany) partial glycolysis process.

“The implementation risk for these processes is low, but the rewards are small. These platforms have additional limitations. For instance, both the FTR, and the Equipolymers processes require relatively clean rPET feedstock, and can only be used to produce packaging resins containing up to 30% recycled content,” Bell notes.

Still, before chemical recycling reaches a scale-up phase, consumer behavior needs to support the expanded collection infrastructure that would be required to feed the chemical-recycling plants of tomorrow, says Bell.

Learn more on PET recycle during the Technology Seminar at the World Petrochemical Conference in New Orleans, Louisiana March 24-27, 2020.