The promise of chemical recycling

At a time when headlines scream about plastic choking the oceans, companies around the world are searching for ways to repurpose end-of-life plastics. For some, the answer might be found in a philosophy of better living through chemistry.

Proponents say chemical recycling offers a way to recover plastics that are unsuited to traditional mechanical recycling methods. Most chemical recycling operations are just now emerging out of the experimental phase.

Chemical recycling processes vary, but they typically follow this template: Plastic is chopped up and treated with some combination of water, heat, pressure and enzymes or catalysts, breaking the resin down into its constituent parts. These chemicals can be repolymerized into virgin-quality resins or used as fuel or as the raw materials for other products.

“Chemical recycling will enable brand owners to produce plastics made at 100 percent from reused material,” says M. Benjamin Audebert, director of investor relations for Carbios S.A., based in Saint-Beauzire, France. “It’s clearly the only way for global brand owners to fulfill their sustainable commitments and for recyclers to better value the plastics that are currently landfilled or incinerated.”

Many of the innovations are still in a nascent phase, with companies, including startups, looking to scale up.

Agilyx Inc.

Agilyx Inc., Tigard, Oregon, is one of a few established chemical recyclers in the U.S. Its technology for recycling mixed plastics has yielded more than 800,000 gallons of crude oil that the company sells to refineries to be made into products such as low-carbon recycled jet fuel, gasoline and plastic resin.

“Agilyx has developed a comprehensive platform over the past 14 years that can effectively convert a broad range of plastics to a broad range of high-quality fuels and chemical substrates,” says CEO Joseph Vaillancourt.

Earlier this year, Agilyx ret

In the process, Agilyx first analyzes the feedstock to be recycled. It densifies the foam and shreds the plastic to a consistent size. Once the material is prepared, it’s heated up in a reactor in the absence of oxygen.

Vaillancourt says, “The styrene pathway is exciting for us as it has quickly led us to be able to take different mixes of waste plastics and convert [them] into chemical intermediates that can be used to make a variety of new plastics and polymers.”

Carbios

Carbios, a green chemistry company focused on plastics recycling, is targeting polyethylene terephthalate (PET)—a resin it believes offers huge market potential.

The company has developed what it claims is the first biological process to infinitely recycle PET. It uses a reactor to catalyze a reaction involving enzymes, PET and water. At atmospheric pressure and a temperature of 149 F, it can depolymerize PET into its original building blocks—purified terephthalic acid (PTA) and monoethylene glycol (MEG). The process allows the recycling of all types of PET items and polyester fibers, Audebert says.

Carbios is running a pilot project in a 1,000-liter reactor at its headquarters. The Carbios process starts with mixed PET that is shredded into flakes, which are placed in the depolymerization unit. Water and the Carbios enzyme catalyst are added, and the brew is then heated. After 16 hours, 97 percent of the mixed PET is converted into PTA and MEG. The company says it is improving the enzymatic reaction to speed up the process. It is working with an oil and gas company to scale up the technology for industrial production. Carbios anticipates the technology will be ready for demonstration by 2021.

Recycling Technologies Ltd.

Recycling Technologies Ltd., Swindon, England, employs thermal cracking to break down mixed plastics that can’t be recycled economically by mechanical means. The process produces a low-sulfur oil, dubbed Plaxx, which can be used to manufacture food-grade plastics, says Adrian Haworth, the company’s marketing and sales director.

The company’s system, called the RT7000, has a pretreatment and materials separation unit where moisture, organic materials and inert materials are removed. In its thermal cracker, which uses fluidized beds featuring ceramic beads, the plastic is subjected to high heat in the absence of oxygen, which breaks long-chain molecules into shorter chain hydrocarbons. The hydrocarbons are condensed into Plaxx, which then can be used as a feedstock for plastics, wax and fuel.

The unit is designed to process 2,204 pounds per hour of dry plastic scrap for 7,000 hours per year, or about 15.4 million pounds. It will make 11.4 million pounds of Plaxx from that total, Haworth says.

The thermal cracker is designed for installation at existing recycling centers. The company says it hopes to build 1,300 machines in the next decade.

Image: BioCellection Inc.

BioCellection Inc.

Startup BioCellection Inc., Menlo Park, California, is targeting plastics that would otherwise be landfilled because of contamination or lack of mechanical recycling options. It is focused mainly on low-grade polyethylene film.

The company’s prototype machine uses liquid catalysts and doesn’t require plastics to be clean before recycling. The device triggers a chemical reaction at atmospheric pressure and a temperature of 284 F. Once the polymer is broken down into molecules with fewer than 10 carbon atoms, oxygen from the air adds to the chain, resulting in the production of dibasic esters, molecules that can replace petroleum as building blocks for new plastics. With an input of 2.2 pounds of contaminated films, the process takes only three hours and produces 1.5 pounds of final product, according to the company.

“The chemicals that we make occupy multibillion-dollar existing markets and are used as essential precursors for polymers, solvents and new materials,” CEO Miranda Wang says.

The company is working on what it believes are the final technical challenges to its scalability pilot.

While BioCellection would compete against chemical producers that use petroleum as their raw material, the company’s business model allows it to sell its chemicals at the same price or cheaper, she says. Wang says Bio- Cellection also will face some operational challenges as it begins integrating its technology into existing MRFs. The company plans to begin licensing its technology early in 2019.

Image: Loop Industries Inc.

Loop Industries Inc.

Like BioCellection, Loop Industries Inc., Terrebonne, Quebec, uses a catalyst. The patented catalyst breaks down PET material—including mixed PET and polyester fiber—without the use of heat or pressure. The technology doesn’t require sorting, but shredding speeds up the process, as smaller pieces depolymerize more quickly.

Nelson Switzer, chief growth officer for Loop Industries, touts the company’s heat-free process. “This means the energy inputs are lower and the overall PET yield is much higher—a commercially and environmentally efficient process.”

The process yields dimethyl terephthalate (DMT) and MEG that the company repolymerizes its Loop-branded PET that is suitable for food contact. The company also makes Loop polyester fiber.

“We can use the material that others cannot as feedstock in our process,” Switzer says. “For instance, the fines generated from mechanical recyclers that may contain paper or other plastics and contaminants or ocean plastics that have been degraded by the sun can be processed through our technology.”

He is optimistic about the company’s prospects. “The greatest challenge at the moment is growing fast enough to meet the demand we face,” Switzer says. “Feedstock is readily available, the technology is proven and customers are abundant.”

Market demand

In August, recycler ReNew ELP, Redcar, England, and Finnish refinery company Neste agreed to partner to use plastic scrap as a raw material to produce liquid hydrocarbons, chemicals and new plastics.

ReNew’s process turns end-of-life plastics into stable synthetic oils and petrochemicals. The catalytic hydrothermal reactor (Cat-HTR) technology it uses, developed by Australian company Licella Holdings Ltd., employs very hot water at high pressure to break down a variety of feedstocks, including end-of-life plastics, into biocrude or synthetic crude oil.

ReNew is building the first commercial-scale plant using the Cat-HTR technology in England; it is scheduled to begin operating by the end of 2019. Initially, it will process 44 million pounds of plastics per year, with plans to eventually increase that to 176 million pounds annually.

Coca-Cola also has expressed interest in the chemical recycling of plastics. Maria Luisa Polli, technical director of Coca-Cola Central & Eastern Europe, has joined the advisory board of Demeto, a European consortium based in Brussels that is developing chemical recycling technology with funding from the European Union. Demeto, named by abbreviating “depolymerization by microwave technology,” is working to commercialize technology that uses microwaves to break down PET and repolymerize it into food-grade resin. Gr3n Recycling, Castagnola, Switzerland, invented the technology.

“We have a target for all of our plastic bottles to contain at least 50 percent recycled material by 2030,” Polli says. “We’re looking for the fastest ways to get there even earlier if we can. Technology like this opens up that possibility.”

The author is a correspondent for Plastics Machinery Magazine and can be reached at agerlat@plasticsmachinerymagazine.com.