Trinseo pursues sustainable future for PS

Materials supplier Trinseo is out to improve polystyrene's public image.

Many people do not realize just how much PS is used, said Julien Renvoise, recycling and marketing manager for Europe, the Middle East and Africa at Trinseo. To begin with, polystyrene is one of the "best" materials available for food packaging.

"It's been used for the past 70-80 years." And while it is, for the most part associated by many with single-use and disposable applications, it has found much wider application in other sectors as well.

As he told Sustainable Plastics during a recent telephone interview, PS is also the material of choice for refrigerator liners and, when foamed, serves as the core material in insulation panels. This ubiquitous use of PS means that it is imperative to seek the best disposal solution for the material at the end of life.

"Of course, we need to consume less, and to generate less waste. And for the waste that we have, we think that recycling is the best way to dispose of these materials," Renvoise said. Yet while mechanical recycling is an excellent solution in many cases, the "complex, multi-layered structure of much packaging, that is moreover often highly contaminated," presents a challenge.

"Moreover, we see a big deterioration in properties with mechanical recycling," he said. This is the reason why Trinseo is looking at other solutions.

The company has been a major driver behind the development of chemical recycling processes for PS — the "holy grail to address the challenge of plastic waste," Renvoise said.

"Chemical recycling offers a broader scope, but it costs more energy. There is an urgent need for a parallel development: In other words, not one or the other, but both kinds of recycling are needed if we are to reach the recycling targets of the European Commission," he explained.

And PS is a polymer with unique circularity potential, as it is most easily reversed into its original monomer, at high yield, with the help of the latest chemical recycling technologies. The liquid state of its monomer enables easy purification and the recycled monomer is identical to the virgin monomer. It can thus be processed into virgin-like styrenic polymers, suitable for all applications, including food contact. Also, from there it can be continuously recycled, over and over again.

Three years ago, Trinseo, based in Berwyn, Pa., decided to put its money where its mouth was when it became one of the founding members of an initiative launched by PlasticsEurope to promote innovative recycling solutions for polystyrene, in a push to support the European Union's circular economy plan. Known as Styrenics Circular Solutions (SCS), the initiative emerged a year later as an independent legal entity after its four founding members — Ineos Styrolution, Total, Trinseo and Versalis (Eni) — all of which were styrenics suppliers, signed the SCS incorporation agreement.

The platform has since been joined by other members from across the styrenics value chain and has made significant progress on the development of technologies aimed at enabling polystyrene, EPS and other styrenic based plastics to be fully recycled so that they can be reused in high-quality applications, ultimately also for food contact.

"We, SCS, are the voice of styrenics recycling," said Renvoise. He emphasized that communication was one of the three pillars on which the platform was founded.

"We have three aims: We want to develop the best recycling technology for styrenics; second, we are seeking to develop the right waste stream to collect the waste — it is vital that we have the right feed; and third, we need to communicate our message. Brand owners, retailers, converters, recyclers: they all need to know about us," he said.

Next to the SCS initiative, Trinseo has embarked on other chemical recycling projects in collaboration with partners, both in Europe and in the United States. Via polystyrene supplier Americas Styrenics, a joint venture equally owned by Trinseo LLC and Chevron Phillips Chemical Co. LP, AmSty has set up Regenyx, a joint venture with Agilyx, an Oregon-based chemical recycling company that has developed technology to convert waste plastics to low carbon fuels and chemicals.

The process, called PolyUsable, converts used PS products into styrene monomer. The recycled styrene can be used to make new PS products without any degradation of quality or value. The new joint venture, Regenyx, took over the assets of Agilyx's Oregon facility, which was already shipping recycled styrene monomer to AmSty.

Trinseo is also collaborating with Ineos Styrolution and Agilyx in Europe, to build a commercial-scale chemical recycling plant in Europe, at a location that remains to be announced.

"The new plant will be capable of processing up to 18,000 metric tons per day of post-consumer PS feedstock into styrene oil, which will be used by Trinseo and Ineos to produce virgin quality PS," Renvoise said.

Trinseo has two "well-located" plants in Europe, he continued, one in Tessenderlo, Belgium, and another in Schkopau, Germany, which will process the styrene monomer from the project.

"It will be operational by 2022," Renvoise said. The project was initiated by SCS as part of the commitment to drive up European styrenics recycling rates and follows the promising results of an evaluation study in which SCS, engaged Agilyx to perform tests with samples of post-consumer PS food packaging waste.

Agilyx evaluated the composition of the waste feedstock and successfully recycled it back into its original liquid monomer. Another project involves a collaboration with a Belgian recycler who has developed a depolymerization process in which polyolefins are broken down into naphtha and wax, while PS waste is depolymerized into styrene monomers.

Critical to the success of all these initiatives, however, is the need for the basics to be in place and functional.

"We need a fundamental focus on each step: collection, sorting and recycling," Renvoise urged.

"In many countries, we see the recycling goals outpacing the waste collection. In France, for example, the blue bin or yellow bin scheme currently applies in only 40 percent of the country. This will reach 100 percent by 2022, so that curbside collection of waste plastic is available to everyone," he said.

Recyclers also need to rethink their sorting procedures.

"PET, LDPE, PP — these materials are all well sorted at the sorting centers. PS is not that well sorted, which means that efforts are required on the part of the PS suppliers to convince them that this material is worth sorting," Renvoise noted.

"We are taking a long-term commitment with them, to demonstrate the investment is worthwhile."

The growing awareness of consumers is the main force behind the push for more recycling, Renvoise said. This increased consumer awareness is also felt by the public authorities, which has led to a broad range of new goals, rules and regulations on the national and European level regarding recycling and circularity.

"What we need is a scientific, rather than an emotional approach," he said. "As a value chain, we need to collaborate in order to achieve the goals we have set. And we need to communicate better. Obviously, as an industry, we have a credibility issue. But we consider that to be simply another challenge we must seek to overcome."