New market study explores advances in chemical recycling technology

In its latest report entitled Chemical Recycling and Dissolution of Plastics 2023-2033, independent market research firm IDTechEx Chemical has examined the early-stage technologies for chemical recycling and assessed the players and likely commercial impact.

The report includes independent market forecasts, industry analysis and critical technical assessment on pyrolysis, depolymerisation, gasification, and dissolution processes; both those in use today and being proposed for the near future.

In chemical recycling, end-of-life plastic is converted back to either its monomeric feedstock or further upstream to raw materials. These then re-enter the value chain at virgin-grade quality, a process that, in theory, can be repeated an infinite number of times.

It is a promising approach but one that has caused considerable controversy. The environmental credentials and economic viability of the different chemical recycling processes have come under frequent and heavy criticism from opponents, while advocates of the technology tend to present it in an all-too-positive light. The reality is that the merits of these technologies are still emerging; their benefits and limitations are still being evaluated.
So what are these technologies? IDTechEx Chemical has compiled an overview of the most common ones in use.

Depolymerisation
Depolymerisation is one of the most exciting areas of chemical recycling; it involves breaking down polymer chains into their monomers. This is not appropriate for all polymers, but it can be highly effective for some. The monomer will also hold more value than a raw material, but there are challenges, including the process conditions and the requirements of a more homogeneous waste feedstock, to give two examples.
Currently, the two main materials focused on in this space are PET, which can be depolymerised via methanolysis, hydrolysis, or glycolysis; and the thermal depolymerisation of PS. PET depolymerisation is a key focus area that is being explored by both young companies, like Loop Industries, and major industry players, including Eastman.
According to IDTechEx Chemical, there are two processes close to larger-scale deployments that warrant a further look. The first is enzymatic depolymerisation and the main player in this space in France-based Carbios, who announced in 2022 that they would build their first plant in partnership with Indorama Ventures. They have a JDA with Novozymes to produce the proprietary recycling enzyme and end-user partnerships, including Pepsi, L'Oréal, On, Patagonia, Salomon, PUMA, Nestle Waters, Suntory Beverage & Food Europe. Carbios are not alone, as many others enter this field. Another emerging company is Samsara Eco in Australia.
Microwave-assisted depolymerisation is the second depolymerisation technology of interest. In thermal depolymerisation, achieving efficient heat transfer is essential; this is where microwaves could play a role. As with enzymatic processes, academic interest has been very considerable, but the commercial success stories are increasing. One of the key players in the field is Pyrowave. Pyrowave have been operating a reactor for PS for many years and have reported that their recycled product has already gone into many finished goods. Michelin is a key investor and is in the process of installing their first multi-reactor project with the product utilised for their styrene-butadiene rubber. There are others exploring microwaves, including Microwave Chemical in Japan, who work with Mitsubishi Chemical on PMMA and other engagements, and Gr3n, who received 2021 funding from Chevron Technology Ventures and Standex International, looking at PET.

Pyrolysis
Pyrolysis is a familiar technology backed up by decades of research and commercial exploration. Currently, major commitments made by major petrochemical players such as BASF, Sabic, and ExxonMobil are driving the market. In 2022 alone, Encina announced a US$1.1 billion investment in a new plant; Plastic Energy progressed in their commercialization with announcements surrounding TotalEnergies, INEOS, LyondellBasell, and Qenos; and Honeywell announced a strategic agreement with TotalEnergies and a JV with Avangard. However, the technology is highly controversial: in 2022 lawmakers and environmental groups submitted over 100 letters to the Environmental Protection Agency on the regulation of this technology. The uproar has led to setbacks, as well:  Brightmark Energy, for example, scrapped plans for a US$680m plant in the state of Georgia.

One of the more notable technology developments in a related field is hydrothermal liquefaction. Here, supercritical water and a catalyst are used to break mixed polymers into long chain hydrocarbons. One of the reported advantages is the ability to tolerate lower-quality mixed material feedstocks, specifically those with a higher proportion of PVC, which is a key problem in pyrolysis. As with pyrolysis, this is not new, but newer companies such as Mura Technology, for example, are currently gaining significant momentum, progressing to strategic partnerships and planned projects with the likes of Dow, Mitsubishi Chemical, and LG Chem.

Similarly, gasification is also not a new process and has been extensively deployed to remove municipal solid waste (MSW), particularly in Japan. What is changing is the idea that syngas generated need not be used for on-site energy, but rather it can be purified and converted into longer chain hydrocarbons, methanol, or ethanol. With the ability to use MSW, gasification acts as the final option for any circularity before incineration. Players are exploring this. Enerkem is one of the more notable players, and their first commercial plant opened in 2014. As of late 2022, Enerkem has a further plant under construction for 2023, and two more are being planned. It should be noted that, as with pyrolysis, although the product can re-enter the supply chain, it often does not and is instead used as a fuel.

Various other processes, ranging from developing polymers with dynamic bonds to facilitate the circular economy, to secondary recycling processes for the dissolution or purification of plastics, are also in various stages of development. Secondary recycling processes are strictly speaking not chemical recycling, but they also offer a promising route to achieving higher-grade materials than other mechanical routes without having to go so far back up the value chain. Players in this field are Trinseo, Purecycle Technologies, APK, Polystyvert, and Worn Again; as with the other processes, many of the younger technology providers have entered into partnerships with major companies across the plastic value chain. An emerging space is ‘physical recycling’: selectively dissolving the polymer and subsequently precipitating this to produce the pure polymer. Ideally, it is a low energy process, and the recycled polymer retains properties closer to that of the virgin material.