Chemical Processing of Plastic Wastes – Dissolution and Extraction; Hydrothermal Processing; and Gasification

In two earlier blogs, I provided, in the first blob, some data on global plastic waste production and chemical recycling.  I also identified various chemical methods being commercialized to recycle plastic waste.  (Click here to read that blog.)  In the second blog, I identified some chemical companies that are developing (commercializing) one of the chemical methods – pyrolysis.   (Click here to read the second blog.)

In this blog, I identify some companies that are commercializing the following methods (other than pyrolysis) for recycling plastic wastes: dissolution and extraction; hydrothermal processing; and gasification.

Dissolution and Extraction – involves the dissolution of mixed plastic wastes in a supercritical fluid and extracting (separating out) the various plastics (polymers) in the mix.   The following are some companies that are investigating the commercialization of waste plastics recycling by dissolution and extraction:

Eastman Chemical.  In a process using methanolysis, the United States company Eastman Chemical uses methanol under pressure and elevated temperature to dissolve polyester-based products and extract various components.

MOL and ARK. The Hungarian MOL Group, a multinational oil and gas company, has a joint project with the German recycling company APK using a solvent-based process to recover high-quality materials from multi-layer plastic packaging containing polyethylene and polyamide.

Hydrothermal Processing – involves heating a waste plastic in water at high temperatures (e.g., 400 to 500 degrees centigrade) and high pressure (e.g., thousands of pounds per square inch), which breaks down the plastic to oils.  The following are some companies that are investigating the commercialization of waste plastics recycling by hydrothermal processing:

Neste and ReNew.   The Finnish renewable oil producer Neste is working with the British plastic recycling specialist ReNew to commercialize a patented version (called Cat-HTR) of hydrothermal processing for generating oils from waste plastics.  A key patented element of Cat-HTR is the use of catalysts (hence the use of Cat in the name).

OMV.  The Austrian oil company OMV has built, in 2018, a pilot plant at its Schwechat refinery using a version of hydrothermal processing to covert waste plastics into oils.

Gasification – involves heating a waste plastic to very high temperatures, e.g., greater than 700 degrees centigrade, in a controlled amount of oxygen and/or stream.  The plastics react (degrade) to form a mixture of carbon monoxide, hydrogen, and carbon dioxide, which can be used as a fuel or to produce methanol and hydrogen.  The following are some companies that are investigating the commercialization of waste plastics recycling by gasification:

Enerkem.  The Canadian company Enerkem is building a plant in Rotterdam, with partners Air Liquide, Nouryon, and Shell, which will use gasification technology to convert waste, including plastic wastes, into carbon monoxide, hydrogen, and carbon dioxide.

Sierra Energy. The United States company Sierra Energy specializes in building smaller gasification plants for use at the local level to treat wastes.

The chemical recycling of plastic wastes has been of commercial and public concern and interest for a long time.  For example, gasification plants using plastic wastes as an input were operating in Japan in the early 2000s.   Many companies have come and gone, failing in successfully commercializing various methods of recycling plastic wastes. 

But in recent years, a stronger public emphasis on the need to deal with the enormous amounts of global plastic wastes has developed.  This has gone along with a stronger public pressure being placed on companies, and recognized by the companies as good business sense, to be good environmental stewards and to identify, and quantify as a marketing tool, sustainability as a critical corporate strategic goal.  With this, more attention seems to be present in recent years by companies on treating plastic wastes, such as those companies identified in the three blogs I have written on chemical processing of waste plastics.  

Although the technical aspects of the methods identified  in these three blogs seem to  be developing successfully, it is likely that commercial success of these methods will be difficult to achieve as long as the value (price) of the resulting products from the methods cannot compete with identical, cheaper products produced from fossil fuels.  This uncompetitive situation is likely to continue for some time without public interventions, e.g. through tax, regulatory, and other governmental incentives.