Can recyclers break the polyester barrier?

In brief

Polyethylene terephthalate (PET) is one of the most ubiquitous plastics, found in everyday items like beverage bottles and salad containers. And in a world increasingly worried about plastic waste, it is among the most recycled resins. But it isn’t recycled as much as it could be. Organizations are looking to improve recycling systems to capture more of the PET objects we use. Some of the solutions are relatively simple, like launching more curbside recycling programs. Others are more challenging, such as building plants that depolymerize PET into raw materials that can be turned into new plastic again.

At its headquarters complex in Kingsport, Tennessee, Eastman Chemical is putting the final touches on what may prove to be a watershed for polymer sustainability.

Eastman is starting up a plant that will use methanolysis to break down postconsumer polyethylene terephthalate (PET) into the raw materials dimethyl terephthalate (DMT) and ethylene glycol. With the capacity to process 110,000 metric tons (t) of PET per year, the plant will be far and away the largest of its kind in the world.

The feedstock for Eastman’s new unit won’t be the clear bottles that feed standard PET recycling plants, which rely on mechanical sorting and washing. Rather, the Eastman unit will take in materials that mechanical recyclers avoid, such as polyester clothing and carpet fibers, green- and brown-tinted PET bottles, and the strapping used to fasten commercial pallets.

“Widening the feedstock aperture” is what Sandeep Bangaru, vice president of circular economy platforms at Eastman, calls it. “I do think there’s a role here where we need to get substantially more coming into the recycling system, not less,” he says. “That needs to be the industry’s goal: How do you get more into the recycling system?”

Maybe a better phrase is “getting even more.” PET is already the most recycled plastic. In the US, the collection rate for PET bottles is nearly 29%, according to the National Association for PET Container Resources. US Environmental Protection Agency figures put the entire plastics recycling rate at 9%. PET’s only rival in US recycling is unpigmented high-density polyethylene bottles—mostly milk jugs—which boast a similar collection rate, according to the EPA.

That needs to be the industry’s goal: How do you get more into the recycling system?

Sandeep Bangaru, vice president of circular economy platforms, Eastman Chemical

But despite its success, the PET sector is under pressure to step up its recycling game. The industry’s customers are demanding it. Coca-Cola, for example, aims to incorporate 50% recycled content across all materials in its packaging by 2030. The company uses 15% recycled PET today.

Other firms, such as PepsiCo, Danone, and Unilever, have similar goals to use far more recycled PET than they do now. And governments will require it too. California’s extended producer responsibility law, which passed in 2022, mandates 30% of plastic packaging to be recycled by 2028. The European Union will require 30% incorporation of recycled content in packaging by 2030.

The PET industry will need to do better if it is to reach such targets. Bringing new chemistry to bear on the problem, as Eastman and other companies are doing with depolymerization, is one strategy. But big gains can be made by simply collecting more material from consumers, improving yields at material recovery facilities, and increasing the recycling of materials, like thermoformed food packaging trays, that the recycling system previously overlooked.

In other words, boosting PET recycling rates will mean improving a system that is already in place and taking advantage of the polymer’s inherent strengths.

A unique polymer

PET is made via the polycondensation of purified terephthalic acid (PTA) or DMT and ethylene glycol. The polymer has been around as polyester fiber since the 1940s. But PET’s properties, such as its clarity, strength, and gas barrier performance—which keeps gases from escaping or entering the container—made it a natural fit in later years for beverage bottles.

Since the first plastic soda bottle, a DuPont innovation, was introduced in the 1970s, PET has grown to dominate the soft-drink market. In the 1990s, PET helped create a market for bottled water. It went on to take food packaging applications like peanut butter and mayonnaise jars away from glass.

The world consumes about 28 million t of PET, not including fiber, per year, according to Ashish Pujari, a PET consultant with Chemical Market Analytics by OPIS.

Credit: Carbios

Carbios developed a machine that shreds clothing for use in its enzymatic depolymerization process.

Luckily, just as it is a natural for packaging, PET lends itself to recycling as well. One reason is that there is so much of it. Municipalities include it in their curbside recycling programs even if they don’t collect plastics like polypropylene. And the critical mass makes it worthwhile for material recovery facilities (MRFs) that process municipal recyclables to separate PET from the metal, glass, and non-PET plastics that they collect. MRFs sell bales of PET to recyclers—also known as reclaimers—that further process it into resins suitable for molding.

Joaquin Mariel is chief commercial officer of Balcones Resources, which operates 11 MRFs in six states, including one that handles the recycling stream of mixed plastics, metal, and glass from New York City.

“PET is definitely the highest volume of the plastics,” Mariel says. About 10% of the recycling stream that Balcones encounters is plastic; of that, two-thirds is PET.

For the reclaimers that are Balcones’s customers, the gas barrier attribute that drives PET’s success in packaging also aids recycling. Being less porous, the plastic can be cleaned thoroughly because contaminants don’t penetrate into its surface as much as they do for polyethylene.

Likewise, the ester bond in PET is a convenient target for chemical recycling, Eastman’s Bangaru notes. “PET is a pretty unique molecule in the polymer world because it lends itself to be readily mechanically recycled as well as efficiently depolymerized into its building blocks,” he says. “Not all plastics have both pathways. PET has a unique capability to get to really high levels of circularity.”

But PET isn’t living up to its recycling potential. Globally, the collection rate is 40–45%, according to Chemical Market Analytics’ Pujari. Because of waste in the system, like material that is rejected, only about 32% of the PET used by consumers—about 9 million t of material—is transformed into final products.

Moreover, most of the processed material, about 80%, is turned into fiber, not the food containers and beverage bottles it came from. Recycling PET into fiber is cheaper than turning it into new bottles because fewer purification steps are needed.

But in the mid-2010s, public outcry over plastics in the ocean made waste from single-use plastics a high priority for the industry. As a result, bottles and other forms of packaging have started to take a bigger portion of PET from the recycling stream. “Up until 2015 or 2016, there was not so much pressure on doing bottle-to-bottle recycling,” Pujari says.

If the industry is to achieve 30% postconsumer content in bottles and packaging, the target some governments have set, the amount of PET recycled into final products globally would need to exceed 17 million t per year, almost twice the current level, Pujari says. The collection rate would have to increase to about 70%.

This is a heavy lift but not an impossible one, Pujari says. The US, with its under-30% collection rate, is an outlier for how poor its collection system is. At the other end of the spectrum, Japan has a collection rate of about 95%, he notes.

The leaky system

People running MRFs and recycling facilities think the problems in the system, particularly in the US, can be mended. To these experts, the problems begin with the consumer, the person that has just finished a bottle of Coke or a salad served in a plastic clamshell.

“The most important thing that we need as a recycler is the collection of bottles,” says Srinivasan Prabhushankar, chief technology officer of recycling at Indorama Ventures. “People should recycle their material. They should bring it back.”

A truck carrying bales of crushed polyethylene terephthalate bottles, such as soda bottles, arrives at an Indorama Ventures recycling plant in Thailand.

Credit: Indorama Ventures

Indorama Ventures operates many polyethylene terephthalate recycling plants worldwide, including this one in Nakhon Pathom, Thailand.

Indorama is the world’s largest PET producer and also one of the largest recyclers. Prabhushankar says the industry has ample PET recycling capacity. What it needs is more material to process. “The infrastructure is being developed. The last piece is the behavior piece,” he says.

But consumers don’t always have someplace to put their bottles. “Not everybody has a convenient recycling program,” says Adam Gendell, director of material advancement for the Recycling Partnership, an industry-backed organization that promotes recycling. For example, according to the Recycling Partnership, 27% of US households do not have recycling pickup that is comparable to their regular garbage collection.

Consumers can do more too. “We know that those that do participate in recycling don’t put all of their PET in the recycling bin,” Gendell says. Among single-family homes in the US that have access to recycling programs, consumers are putting only 47% of their PET containers into the recycling bin. They are recycling even less, 40%, of thermoformed PET items like berry containers and clear plastic egg cartons.


Plateau


The US recycling rate for polyethylene terephthalate bottles has dipped in recent years.


Source: National Association for PET Container Resources.

“We really want to see consumers just recycle more,” Balcones’s Mariel says. All the municipalities that his company serves conduct waste characterization studies, which find valuable materials are thrown away. “And you’re still seeing high volumes of very easily recoverable and easily marketable grades of material like aluminum, PET, and cardboard,” he says.

One important caveat is that “bottle bill” states, which charge consumers deposit fees on bottles and offer redemptions if they return the bottles to the store, have much higher collection rates than states that do not. The capture rate of bottles in California, where Indorama operates a plant, is approximately 70% because of the state’s deposit law, Prabhushankar says. Alabama, where the firm also operates a plant, has only curbside collection, if there is a recycling option at all. It has a capture rate of about 10%.

“If there was a national bottle bill, then the quality and the quantity of the material would go up big time,” he says.

Also nagging PET recycling are the yield losses within the system itself. According to Gendell, MRFs on average miss one out of four PET bottles that enter the system. “Some MRFs are doing a good job and probably getting like a 95% capture rate, and others might literally be more like a 50–60% success rate,” he says.

Prabhushankar says the quality of the plastic the company gets from MRFs has been slipping in recent years—there has been more contamination, like aluminum cans and glass bottles. “I buy a pound of material, but am I able to make half a pound out of that, or three-quarters of a pound out of that? It depends upon what is the quality of the incoming stream,” he says.

Antonio Garza, vice president of recycling at Alpek Polyester, another large PET producer and a major recycler, agrees that quality has been deteriorating. “Reinvestment is needed in the facilities,” he says.

Balcones’s Mariel disputes the assertion that quality is on the decline, at least as far as his company is concerned. “When we think about yield, we’re thinking about how much PET we are yielding from the total stream, and we have not seen that go down,” he says.

But not every facility is the same. “There’s a lot of old infrastructure in certain regions,” Mariel says. For example, some MRFs still rely on hand sorting instead of automated optical equipment.

Mariel says MRFs are constantly trying to keep up with the “changing ton.” Consumer habits evolve over time, and so does the waste. For example, when Balcones completed its plant in Austin, Texas, 12 years ago, PET was only 2% of the waste stream. After volumes of PET swelled, the company installed additional optical sorters to capture it.

Last year, the Recycling Partnership launched the PET Recycling Coalition to award grants to reclaimers and MRFs to help them purchase such new equipment. In its most recent quarterly round, it awarded $900,000 in grants.

Gendell says the grants create incentives for making PET recycling improvements a high priority for MRFs and reclaimers. “The MRF has kind of a top 10 list of improvements that they’d like to make, and the types of improvements that we’d like to make might not be on the top of that list,” he says.

Beyond the bottle

The coalition has a particular interest in helping MRFs and reclaimers invest in the capacity to process thermoformed PET containers—the clear clamshells that house berries, salad, and eggs. Balcones received a grant so it could invest in processing thermoforms separately from bottles at the Austin plant.

Thermoforms aren’t as widely recycled as bottles. Only 55–60% of US households have access to thermoform collection, the Recycling Coalition says. And the materials can be challenging to recycle. For example, the labels used on thermoforms are notoriously difficult to remove.

Gendell sees a lot of untapped potential in thermoforms, which compose 15–20% of the PET packaging market. “We now see mechanical reclaimers that have been designed especially for thermoforms,” he says. “And that’s sort of a new wave that I think is really promising.”

One of the trailblazers is Direct Pack, which makes thermoform containers with recycled content for companies such as Chick-fil-A, Costco, and the Cheesecake Factory. Companies like this have desired more resins, particularly from thermoforms, in their packaging. For example, Driscoll’s uses 50% recycled content in its berry containers and wants to use as much material derived from thermoforms as possible.

Direct Pack operates a recycling plant in Mexico that supplies resin to four thermoforming plants in the US and Mexico. Because customers demand it, Direct Pack is focused on acquiring thermoform containers to recycle. “We thought it was going to be a big challenge, but it has actually turned out to be a big success,” says Andrew Jolin, Direct Pack’s director of sustainability.

Direct Pack has created a market for waste thermoforms, starting in California. There, MRFs have traditionally bundled mixed bales of plastic containing both PET bottles and thermoforms. Direct Pack is a willing buyer of thermoforms, providing an incentive for the California MRFs to separate and make bales of thermoformed containers. It buys bales from between 10 and 15 MRFs; another 10–20 are interested in participating.

The firm has received two grants from the PET Recycling Coalition. One is to expand its recycling line in Mexico. Another will help it build a new line in North Carolina, which the company hopes will lead to a similar thermoform recycling system in the Southeast. When the company completes these projects, it will be able to process a total of 100 truckloads of thermoform bales per month.

Depolymerization’s promise

Much like Direct Pack is opening up new vistas in PET recycling by creating a market for thermoforms, companies developing depolymerization technologies are offering a solution for even-less-desirable PET-containing materials than bottles or thermoforms.

Depolymerization, often referred to as chemical recycling, comes in a few different forms. Hydrolysis uses water to break the ester bond in PET, yielding PTA and ethylene glycol. In methanolysis, methanol works on that bond to divide the polymer into DMT and ethylene glycol. And glycolysis uses ethylene glycol to break PET into bis(2-hydroxyethyl) terephthalate (BHET). All these products can be turned back into PET via condensation polymerization.

Depolymerization has its skeptics. One is Anja Brandon, associate director of US plastics policy at the Ocean Conservancy. “We can mechanically recycle PET; we just need to do a better job collecting it and cleaning it and separating it from other things,” she said in a recent webinar. Of depolymerization, she said, “What problem are we really solving?”

Critics often point out that depolymerization is more energy intensive than mechanical recycling. Companies involved in depolymerization readily concede the point. “Of course from an energy or energetic point of view, mechanical recycling is better than chemical recycling,” says Fabio Silvestri, head of marketing and business development at one such firm, Gr3n. “But we are doing two different things. They are washing a car; we are disassembling a car and then cleaning each piece. So the energy consumption is different.”

They are washing a car; we are disassembling a car and then cleaning each piece.

Fabio Silvestri, head of marketing and business development, Gr3n

And polymerization firms see the bottom line as the energy savings versus making virgin PET. Eastman, for example, claims PET made using its methanolysis process is 30–40% less greenhouse gas intensive than PET produced from new raw materials.

The developers of depolymerization technology think they will solve meaningful problems.

“We think that chemical recycling will always complement mechanical recycling,” Indorama’s Prabhushankar says. For example, the mechanical recycling process produces fines, particles that are too small for further processing. In addition, depolymerization can treat X-ray films, pigmented resins, polyester clothing, and everything else containing PET that mechanical recycling can’t handle. “All this material will become the feedstock of chemical recycling,” he says.

The fiber market alone is about twice the size of the PET polymer sector in terms of annual production, according to Chemical Market Analytics.

Another problem that depolymerization aims to solve is quality. Mechanical recycling can attain the high levels of purity needed for food-grade applications only through meticulous sortation, repeated washing, and the application of heat and vacuums to draw molecular contaminants from the polymer. The resins are also run through a solid-state reactor, which brings the molecular weight of the polymer, and thus the intrinsic viscosity of the plastic, up to a level that is suitable for packaging.

But the process is laborious and expensive. And just a few parts per million of contamination will make the neck of a 100%-recycled-content plastic bottle look hazy. Chemical recyclers, in contrast, are able to achieve higher levels of purity by employing techniques such as crystallization and distillation on the monomers they produce.

Attaining high purity is the focus of Revalyu Resources. The company, backed by the German industrial conglomerate Heraeus Holding, intends to build a $50 million glycolysis-based recycling plant in Statesboro, Georgia, by the end of 2024.

Breaking down polyester

Reaction equations for PET hydrolysis, methanolysis, and glycolysis. Hydrolysis produces terephthalic acid and ethylene glycol. Methanolysis produces dimethyl terepthalate and ethylene glycol. And glycolysis produces bis(2-hydroxyethyl) terephthalate.

The depolymerization of polyethylene terephthalate (PET) has emerged as a potential improvement over the repeated washing of mechanical recycling. The processes essentially run in reverse of the polycondensation reactions used to make PET in the first place. They yield molecules that can be chemically purified and polymerized into PET that is indistinguishable from virgin PET made from fossil raw materials. And depolymerization plants can take in feedstock, like discarded polyester garments, that mechanical recycling can’t.

Revalyu is taking a different approach than Eastman, which aims to process hard-to-recycle materials. Revalyu will buy PET flake from mechanical recycling plants. It will apply the glycolysis process to the material, breaking it down only to the PET oligomer, not all the way down to BHET. It will then filter the oligomer to remove impurities and repolymerize it to PET.

Vivek Tandon, Revalyu’s founder, sees Revalyu’s processes as a finishing step for resins that have gone through a “rudimentary clean” in mechanical recycling. In achieving the high levels of purity needed for food-grade applications, the mechanical process suffers from diminishing returns, he says. “At a certain point, washing does not get the product that much cleaner, and the costs go up and the carbon footprint goes up because there’s a lot of hot water.”

Revalyu has been running a glycolysis plant in India since 2012, making polyester fiber from waste PET. Tandon claims that it is the first plant in the world to conduct depolymerization profitably.

Using glycolysis to upgrade mechanically recycled material isn’t that unusual in the PET industry. Alpek has been doing it since 2016. While some of the resins from its mechanical recycling plants go directly to customers, others go through an oligomer-yielding glycolysis process. The oligomer is reacted with virgin polymer at an intermediate stage of polymerization to create a product that has up to 25% recycled content.

“The value you are adding when you depolymerize is that you go to a much lower viscosity, so you have the ability to filter much smaller particles,” Garza says.

Eastman has been running a small glycolysis plant since 2020 in Kingsport, where it uses DMT to make specialty polyester copolymers. It exited the commodity PET business a decade ago.

For the new plant in Tennessee, Eastman is opting for methanolysis. Bangaru says the reason is purification. BHET can be crystallized, but DMT can be crystallized and distilled. As a result, methanolysis can handle dirtier feedstock than glycolysis can.

A chemical plant under construction with scaffolding and cranes.

Credit: Eastman Chemical

Eastman Chemical is putting the final touches on a plant in Kingsport, Tennessee, that will break down polyethylene terephthalate into the raw materials dimethyl terephthalate and ethylene glycol.

With methanolysis, Eastman can go after colored PET, carpet fiber, blended plastics, and resins rejected from the mechanical recycling system. “Methanolysis is really what we believe is the technology that’s required to have a much broader aperture of feedstock,” Bangaru says.

Eastman aims to make PET recycling a major new business. It is planning a second plant in Port-Jérôme-sur-Seine, France, that will have 160,000 t per year of recycling capacity when it starts up around 2026. As part of that project, expected to cost about $1 billion, Eastman will build polymerization plants that will make both its specialty copolymers and standard PET, bringing the company back, through recycling, into a business it exited.

Eastman is also planning a second US facility that, like the one in France, will have the ability to make PET resins. The company has already signed a supply contract with PepsiCo, which will buy a large part of that output. Eastman hasn’t decided on a location yet, but it recently filed for tax breaks to build the facility at its complex in Longview, Texas.

France will also see a second major depolymerization project. The start-up Carbios is planning a plant in Longlaville based on an enzymatic hydrolysis process that produces PTA and ethylene glycol from PET. The plant, which will be able to process 50,000 t of waste PET per year and is scheduled for commissioning in 2025, will be adjacent to an Indorama PET plant. Indorama is coinvesting in the depolymerization unit and will use the output to make fiber and PET.

Emmanuel Ladent, Carbios’s CEO, has an ambition to capture 4–8% of the PET recycling market by 2030. He sees advantages for the enzymatic approach over methanolysis. For instance, it yields PTA, which is the raw material for the vast majority of PET plants.

To feed the French plant, Carbios will buy PET bottles as well as alternative feedstock. “Food trays and polyester fibers are not currently recycled, and they are either incinerated or landfilled,” Ladent says, noting that they are cheaper to acquire than bottles. “That’s where we see a big opportunity.”

The company already has agreements to acquire about 30% of the discarded food trays in France. It has also developed a machine for preprocessing textiles. It shreds the garments and removes nonfiber elements such as zippers and buttons.

Recycling fibers opens up new demand, Ladent says. Many clothing brands already use recycled PET, but it normally comes from bottles. “They want to move away from bottle to fibers,” Ladent says. “They want to go fiber to fiber.”

Like Carbios, the Swiss firm Gr3n is conducting hydrolysis with a twist. It breaks down the polymer in water using sodium hydroxide. But instead of heating the vessel from the outside, the firm uses microwaves to assist in the reaction.

Silvestri says heating up the particles directly makes the reaction go much faster. It is finished in 10 min when a normal reaction could take hours, he says.

The company, along with its major shareholder, the Spanish engineering firm Intecsa Industrial, is building a plant in Spain that will be able to produce 40,000 t per year of recycled PET by 2027.

Gr3n got its start in 2011 when its founders Maurizio Crippa and Matteo Parravicini met at the University of Milano-Bicocca. “The request for chemical recycling was more or less zero in 2011,” Silvestri recalls. “Sustainability was not yet the buzzword. We were lucky because everything changed.”

Everything has indeed changed. It was not so long ago that the world was complacent about recycling and didn’t yet see plastic waste as a global crisis. But many of the problems in PET recycling are identified, and the industry seems to have a new determination to finally solve them. For PET, if not for other plastics, a revolution in recycling is perhaps within reach.


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