What was Old is New Again: Chemical Recycling of Plastic Waste using Pyrolysis

By Rosemarie Szostak, Ph.D., Ben Bahavar, Ph.D., Richard Maldanis, Ph.D.

Originally Published February 3, 2023

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Recycling has been popular for over 50 years, but there are still growing pains.

Mechanical recycling of plastic has been the primary approach, yet it remains to have serious issues. Recycling plastic using mechanical techniques (shredding, grinding, melting, etc.) is a challenge since a) it degrades the properties of the polymer during processing and b) improper sorting will affect the purity of the output. Chemical recycling, though, has been slow to catch on. Until now.

Chemical Recycling Using Pyrolysis

Pyrolysis is the thermal decomposition of any organic compound when heated in the absence of air. The products of this process, depending on the conditions, can consist of (H2/CO)/lower hydrocarbons/aromatics.

Products of the pyrolysis of organic material have been used as early as the 12th century. The process produced pine resin used for waterproofing wooden ships and impregnating ropes. It became commercial in the 16th century for this application. WWI precipitated the need for aromatic compounds from the pyrolysis of biomass to make the explosive TNT. After that, the production of aromatic compounds from waste languished for 60 years.

The first interest in the pyrolysis of mixed plastic waste to form the aromatic compounds benzene, toluene, xylene, referred to as BTX, began in the early 1970s in both the academic as well as patent literature. During this period, environmental conservation came to the forefront in the US and around the world precipitating an interest in recycling on a large scale.

In 1976 there were the first three academic articles from a group in West Germany discussing the use of pyrolysis of waste plastic and tires for chemical recycling. Fast forward to the 2020s and the number of papers ballooned exponentially, with 123 papers published in 2022 alone, up from 100 in 2021 and 62 and 45 in 2020 and 2019, respectively. In this sector, most of the academic funding for chemical recycling to produce BTX is from government agencies in China, followed by the EU. While hurdles remain at the federal level within the US on utilizing pyrolysis techniques for chemical recycling due to it being energy intensive and environmental concerns, states are promoting its use. As of 2022, 18 states have passed laws regarding this as a viable recycling technique (read the article here).

Patent activity has also exploded recently. SABIC is the leading company with the most first-time patent filings for the conversion of waste plastic to BTX – these filings were published in 2021 and 2022. SABIC has only filed world patent applications for their recent innovations in the production of BTX using pyrolysis (no first-time US patent applications yet since 2021). Overall, SABIC has 11 pending, eight granted, and four dead patents in BTX production from pyrolyzed waste plastic. Coverage ranges from China, World, US, Japan, EU, and Korea and a few other individual countries, so it is anticipated that these recent patent applications will be filed in the US and other countries. SABIC’s first patent application, specifically in this area, occurred in 2014.

Eastman Chemical and Anellotech have published four recent patent application each. Eastman Chemical has been patenting in pyrolysis of waste for several decades. The start-up, Anellotech, is a recent entrant starting pilot operations over the past decade. They recently announced the possibility of advancement of their technology from the lab to commercial scale with assistance from potential partnering companies. Their technology can use mixed textile wastes, including cotton, polyester, nylon, elastane, acrylic, and polyurethane, a unique application of pyrolysis to a significant waste stream (read the article here).

A recent advancement in commercial chemical recycling of waste mixed plastics to BTX was signed (read the article here) through a Joint Development and Cooperation Agreement with Synova, SABIC Global Technologies, and Technip Energies with their respective MILENA, OLGA, and Pure.rGas processes. This collaborative effort will focus on the development and launch of a new commercial plant to produce olefins and aromatics from mixed plastic waste.

Eastman Chemical has been very active in the circular economy, improving recycling, including chemical recycling. Though several of their processes are in the process of commercialization, their pyrolysis technology has not yet been implemented commercially.

Making new renewable sources for deriving BTX available can have many supply-chain benefits to the petrochemical, polymer, and coating/formulation industry. This will also improve the value of recycling mixed plastic waste and usher plastic waste recycling into today’s circular economy.

So, why is this important to you?

Are you interested in emerging technologies that may impact your business?

How Can Nerac Help?

Nerac can provide you with the backstory for new technologies, who the players are in the space, both in the market as well as the patent literature. These may be your competitors and/or new entrants who could be potential targets for partnership or acquisition. We can provide you with the intelligence you need to understand how these players may impact your business, either positively or negatively.

In parallel, should you desire, we can investigate the academic contributions to a technology area, who is funding the research, and the key players involved. In this latter case, it will allow you to identify academic partners or potential consultants to help you move forward with more arrows in your quiver to keep you on top of your game as you move your company towards a more circular economic model.

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About the Analysts

Rosemarie Szostak, Ph.D.

Rosemarie Szostak, Ph.D., advises companies on technology, patents, innovation and disruptive technology. She has 20 plus years of experience as a thought leader and analyst with broad technical knowledge in chemistry, materials and chemical engineering.

Academic Credentials

  • Post Doctoral Fellow, Chemical Engineering Department, Worcester Polytechnic Institute
  • Ph.D., Chemistry, University of California Los Angeles
  • M.S., Chemistry/Physics, Georgetown University

Ben Bahavar, Ph.D.

Ben Bahavar, Ph.D., advises companies focused on stepping out to adjacent markets where they could apply their core technologies in new ways. He brings particular insight by synthesizing information from technology evaluations (patent and non-patent), competitive intelligence, and market elements.

Academic Credentials

  • Ph.D., Chemical Engineering, Clarkson University
  • M.S., Chemical Engineering, University of Maine
  • B.S., Chemistry, SUNY at Stony Brook

Richard Maldanis, Ph.D.

For over a decade, Richard Maldanis, Ph.D. has been assisting Nerac clients in the specialty chemistry and material science fields. His diverse expertise in organic, inorganic, organometallic and polymer chemistry provides clients with solutions to a broad range of chemistry-related challenges.

Academic Credentials

  • D., Polymer/Organometallic Chemistry, University of Massachusetts-Amherst
  • S., Chemistry, Drew University

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