In a growing corner of the circular plastic supply chain that hasn’t even decided what to call itself yet—chemical, advanced, or molecular recycling are early leaders—it stands to reason that the constituent technologies don't all operate the same. Some chemical and others biological, the processes used to break plastics molecules down from polymer to monomer include solvent-based techniques, pyrolysis, gasification, and methanolysis, among others. While the depolymerization endgame of these processes is awfully similar, the routes to get there are markedly different. So naturally, the inputs used to feed these disparate technologies are also distinct. 
From left, Dan Lief, Resource Recycling (moderator); Candace Rutherford, Brightmark; Holli Alexander, Eastman; Rachel Dial, PureCycle; and Natalie Martinez, ExxonMobil.
This is especially important as more chemical recycling facilities begin rolling out across the U.S., all of which seeking for source streams to keep their chemical recycling beasts fed and producing chemically recycled PCR (cPCR)
This tangled web was highlighted Tuesday at the Plastics Recycling Conference outside of Washington DC, where four representatives of different chemical recycling technologies took the stage to explain their specific paths and supply architectures to sourcing material for their operations.
Brightmark's pyrolysis sourcing strategy
Brightmark is a company with two pillars of complementary technologies: plastics renewal via chemical recycling, and anaerobic digestion of organic waste into natural gas. Candace Rutherford, senior manager, Feedstock, Brightmark focused on the plastics renewal side of the business, explaining that 200 million pounds of plastics are chemically recycled annually by the company’s Ashley Circularity Center, diverting nearly 9 million metric tons of plastic from landfills and waterways. 
“Every hour, two and a half million plastic bottles are thrown away in United States,” Rutherford says. “We all know these bottles have value and they need to be recovered to make into new bottles. But it is a challenge on the supply side of things, trying to harvest the supply that makes it out to the waste stream [to landfill instead of mechanical recycling]. We need to have it to run our plants, so we got to come together and try to come up with some solutions.”
Brightmark takes the pyrolysis route to plastics recovery, perhaps the oldest and most established of the chemical recycling methods. Recovered materials of all different sorts of plastics are first shredded into pellets, then metals and other contaminants are removed. Finally, the pelletized plastics materials are heated and vaporized in an oxygen-starved environment (pyrolysis). The vapor is captured, cooled into hydrocarbon liquid, and processed into commercial grade, low-carbon diesel fuel, as well as the feedstocks for new plastic resins: recycled wax and circular naphtha.
When it comes to finding used plastic packaging feedstocks over the years, she says she has “seen the different collection infrastructures develop as the markets develop. When I was trying to find milk jugs in the 1990s, they were really hard to find because nobody realized the value that they had. As the infrastructure collection came in place, there is more material and more technologies and more capacity. And I'm hoping that this new generation of plastics recycling takes the same course.”
As a longer-established chemical recycling tech, a benefit of pyrolysis is comparatively greater sophistication and scale. The feedstock can be just about anything made of hydrocarbons.
“Materials coming in and shipping that might be foam, might be rigid, might be strapping mixed materials, mixed resins, coated bottles, or laminated films, and that's what we put all that into the same suit to harvest the hydrocarbons,” Rutherford says. “A typical bale might be mixed rigids, mixed colors, it doesn’t matter to us. We can take recycling symbols 1-7 and turn them all back into hydrocarbons.
Eastman’s current gasification, and coming soon, methanolysis
Eastman’s Holli Alexander told a tale of two chemical recycling technologies in the company’s pursuit of circularity.
“One is our carbon renewal technology, which is a gasification technology that's operational today,” she says. “We also have polyester renewal technology, methanolysis, that we're super excited about, and that's going to be starting up this summer.”
The carbon renewal gasification tech breaks different materials all the way down to basic hydrocarbons, CO (carbon monoxide) and hydrogen. Under this methodology, Eastman can take a broader mix of materials (like Brightmarks pyrolysis) and mixed polymer families. A purification and preparation, similar to mechanical recycling, begins the process. The plastics are combined traditional fossil fuels producing syngas (or synthesis gas), which is CO and hydrogen. Eastman uses these as the building blocks to create new plastics, many of which become packaging.
Even though gasification can accept a broad range of feedstocks, that doesn’t mean sourcing inputs is easy. “It’s important to consider that we're focused on streams that do not have good options or good homes within mechanical recycling,” Alexander says. “Eastman is focused on ensuring that what we do is complementary to the mechanical recycling stream. We want to expand the pie, we want to take advantage of what these technologies can do to recycle materials that may not be easily recycled or valued in the mechanical system today.”
The materials Eastman sources then must be feedstock streams that exist today, but cannot be mechanically recycled, or at minimum could be recycled at a much higher value via chemical recycling than they could via mechanical models. This is rare, so Alexander has to seek out material and create streams that don’t yet exist.
“One of the places we've been working on that in automobile shredder residue, through a project with USAMP and PADNOS, part of the US car project,” she adds. “I know we are often focused on recycling of packaging, but there are a lot of plastics that go into a lot of other things. And these technologies, in many cases, are going to be a great way for us to get those recycled.”
In the case of methanolysis, Eastman takes a mix of polyesters, goes through a mechanical preparation and sortation process, and then from that depolymerize and produce that dimethyl terephthalate (DMT) and ethylene glycol. From those stocks, Eastman is able to re-polymerize into materials indistinguishable form virgin (prime). This highly desirable material is turned into some traditional PET bottle polymers, but also into things like reusable packaging or dishwasher durables, really a mix of different outputs.
Sourcing for methanolysis feedstocks is similar to sourcing for the gasification method, but “in this case,” Alexander says, “we're really looking at where's the PET that's already coming through the system that doesn't have a good home. Let's talk about strapping or purge or fines or things like that, that are being created. Partnering, we're working a lot on textiles and carpet. We're doing some interesting work in e efforts like the Recycling Partnership’s PET Coalition to start to build collection channels and mechanisms and expand the pie for things like PET thermoforms, and for colored and opaque bottles.”
PureCycle’s polypropylene-focused sourcing
PureCycle is a solvent-based a polypropylene chemical recycling process that takes polypropylene waste and creates a PP plastic pellet. 
“Our purification process is a physical separation process where we're able to remove color, odor, other plastics, and any other contamination that may be in that polypropylene plastic waste. We use a chemical solvent to dissolve the polypropylene, separate polypropylene from non-polypropylene, and to render it crystal clear, like new recycled pellets,” says Rachel Dial, chief of staff. “Because we're not performing any chemical reaction during our physical separation process, we are not producing any hazardous byproducts or emissions from our process. We have conducted an initial LCA and the good news … is that we're seeing a decrease in greenhouse gas emissions when compared to virgin production by 35%. And then we're also seeing a decrease of our energy footprint, when compared to virgin production, by 79%.”
As a PP-focused chemical recycling technology, PureCycle has to be even more selective with material inputs. But Dial says it’s competitively positioned to source them. It’s supply strategy has four pillars.
· Sorting polypropylene out of curbside materials and mixed rigids (3 through 7s) and residue streams, and upgrading number five bales to increase the polypropylene content to enter it into our system.
· Post-consumer non-curbside, such as international imports and special events. Also new programs such as PureZero. Within this program, organizations that are hosting large events (sports, entertainment) put a strategy in place to recover plastics before they are consumed. This includes PureCycle partnerships with the Cleveland Browns, the Cincinnati Bengals, the Jacksonville Jaguars, and the Orlando Magic. {image caption: recycling at the conference}
· Post-industrial content, direct from manufacturing, including compounding waste and viring production waste
· Advocacy programs, like the Polypropylene Collation. “We’re big fans and supporters of the Polypropylene Coalition. Obviously, they have made amazing strides in increasing the collection around the United States or polypropylene,” Dial says.
ExxonMobil’s Exxtend pyrolysis scales chemical recycling, scales input procurement
ExxonMobil uses another example of thermal pyrolysis technology that can take plastic materials that would be challenging to recycle in mechanical streams, like metalized films, and convert them to certified PCR, virgin-quality polymers. 
“These are plastics that have the same characteristics as virgin resin and can be used in applications such as food-contact packaging or healthcare packaging applications,” says Natalie Martinez at ExxonMobil. “The technology is to take those plastic feedstocks and to break them down to the molecular level. The good thing about our [chemical recycling] facilities is they’re integrated into our existing chemical facilities. So those molecules as they go through those various units, they get processed to the right end-uses, including the certified circular polymers that we produce. So the molecules are basically all captive.”
A big part of the ExxonMobil chemical recycling story is scale. The company’s existing Baytown, Texas facility is a 40,000 ton/year cPCR facility, but it’s just one of many globally.
“ExxonMobil has ambitions to get to 500 KTA [kilotons per anum] capacity by the end of 2026. These are units that will be able to expand multiple different facilities across the U.S., Canada, Europe, and Asia Pacific,” Martinez says. “Something that's really important for us, and what we think is important for the industry, is to be able to do this at scale to create a very meaningful solution for the industry.”
At that kind of scale, sourcing is only exacerbated. That’s why in 2020, ExxonMobil helped to create Cyclyx, a consortium-based supply chain innovation company that understands the chemical complexity of plastic that gets the right waste plastic feedstock into chemical recycling streams. 
PureCycle and ExxonMobil worked with iSustain Inc. to deliver four-stream recycling stations to the conference. Some of the collected materials will be chemically recycled and reprocessed as virgin-quality PCR.
“They're gearing up to find and bring innovative solutions to aggregate and collect plastics for advanced [chemical] recycling and also work on chemically characterizing those plastics. That's something that's not typically done now it is a little bit different and a little bit new. And they're doing that for the industry as a whole,” Martinez says.
How do they pre-process waste that others don’t want to deal with? She cites plastic bottles for car engine motor oil. How do you pre-process that so that it’s not a residual motor oil-contaminated mess upon shredding? Cyclyx is working on those problems.
Exxon is also developing takeback programs at a grassroots, community level. It’s discovering new streams for sourcing its chemical recycling facilities feedstock that way. A new, never-before-tapped polymer supply chain comes from used field turf from athletic stadiums.
“Also, we established the Houston Recycling Collaboration, a diverse partnership with city of Houston LyondellBasell, Exxon Mobil, Cyclyx, and the FCC Environmental Services,” Martinez says. “That collaborative effort was able to bring to life the Kingwood all-plastic takeback collection program. That material will be sorted into both advanced recycling and mechanical recycling destinations.”
MRFs the common thread
While these disparate strategies are reflective of different chemical recycling methodologies and scales, when asked which of the four panelists relied heavily on Materials Recovery Facilities (MRFs) to source their feedstock, all four enthusiastically raised their hands. The growing, and increasingly sophisticated contingency of MRFs in the U.S. and abroad are now employing advanced sortation methodologies of their own, including AI, advanced robotics, and near infrared vision to better sort and supply both mechanical and chemical recyclers. These facilities really are a collective cornerstone unlocking a circular plastics economy. PW
