The Problem Of Waste Plastic And Why Pyrolysis Oil Might Just Contain The Answer
The title of this post, is the same as that of this article on the Chemical Engineer.
These three paragraphs introduce the article.
One of the few technologies that can break down unrecyclable post-consumer waste plastic, pyrolysis is fast becoming a potential recycling route for companies trying to reduce their waste output.
The world produces around 450m t/y of plastic, but only 9% is recycled, with most waste ending up in landfill. Pyrolysis, which involves heating the plastic at extremely high temperatures in the absence of oxygen, breaks down the molecules to produce pyrolysis oil or gas. The oil can then be used to develop new products.
George Huber, a professor of chemical engineering at the University of Wisconsin-Madison, is leading a research team that is investigating the chemistry of pyrolysis oil and its use in polyolefin recycling.
This is a quote from George Huber
Waste plastic should be viewed as a resource we can use to make plastics and other chemicals. We should not be landfilling or burning it, we should be reusing the carbon in waste plastics.
I very much agree with what he said.
These are my thoughts.
Pyrolysis
The Wikipedia entry for pyrolysis starts with this paragraph.
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere.
This paragraph describes the technique’s use in the chemical industry.
The process is used heavily in the chemical industry, for example, to produce ethylene, many forms of carbon, and other chemicals from petroleum, coal, and even wood, or to produce coke from coal. It is used also in the conversion of natural gas (primarily methane) into hydrogen gas and solid carbon char, recently introduced on an industrial scale. Aspirational applications of pyrolysis would convert biomass into syngas and biochar, waste plastics back into usable oil, or waste into safely disposable substances.
I came across pyrolysis in my first job after graduating, when I worked at ICI Runcorn.
ICI were trying to make acetylene in a process plant they had bought from BASF. Ethylene was burned in an atmosphere, that didn’t have much oxygen and then quenched in naphtha. This should have produced acetylene , but all it produced was tonnes of black soot, that it spread all over Runcorn.
I shared an office with a guy, who was using a purpose-built instrument to measure acetylene in the off-gas from the burners.
When he discovered that the gas could be in explosive limits, ICI shut the plant down. The Germans didn’t believe this and said, that anyway it was impossible to do the measurement.
ICI gave up on the process and demolished their plant, but sadly the German plant blew up.
I would assume we have progressed with pyrolysis in the intervening fifty years.
University of Wisconsin-Madison
The University of Wisconsin-Madison is a top-ranked American University and is part of my daily life, as the Warfarin, that stops me having another stroke was developed at the University in the 1940s.
Conclusion
The article is a must-read and I feel that my past experience says, that George Huber and his team could be on to something.
I wish them the best of luck.
The Anonymous Widower 
Sounds like a potential answer to serious problem. I recall seeing an article about using bacteria to ingest plastics some time back. On the face of it a good idea BUT, how do you prevent said bacteria chewing its way through plastics which are still in active use!
Comment by MauriceGReed | May 4, 2024 |