3 ms·

There used to be a startup near me that was turning plastic into crude oil. Looks like they're still around: https://www.agilyx.com/ https://www.agilyx.com/

PaulHoule 3y ago
Polystyrene is relatively easy to depolymerize with enzymes, catalysts and moderate amounts of heat, see https://pubs.acs.org/doi/10.1021/acssuschemeng.1c08400 https://pubs.acs.org/doi/10.1021/acssuschemeng.1c08400 The pyrolysis route they are using can be problematic because it produces carcinogenic aromatic compounds like https://en.wikipedia.org/wiki/Benzopyrene https://en.wikipedia.org/wiki/Benzopyrene which has a metabolite which is almost a cancer-causing drug. In principle you could pyrolyze plastics all the way down to carbon monoxide + hydrogen syngas and then build that up to molecules you want with C1 chemistry https://en.wikipedia.org/wiki/C1_chemistry https://en.wikipedia.org/wiki/C1_chemistry but most of the people who are trying chemical recycling by pyrolysis are trying to cook the molecules partially so the output fuel is a witches brew rich in hazardous aromatics. There is a lot of research into cleaner processes for chemical recycling such as https://www.nature.com/articles/s41598-021-83659-2 https://www.nature.com/articles/s41598-021-83659-2 and that one at the top but every large scale plant I've seen is a pyrolysis plant that's had to fight with environmentalists to start operations. From the viewpoint of a chemical engineer making fuel is for the birds because gasoline costs 50 cents a pound and (almost) any other chemical costs a lot more than that.
- versteegen 3y ago
  > Polystyrene is relatively easy to depolymerize with enzymes, catalysts and moderate amounts of heat Wow. The paper from 2022 so surely noone is using this process yet, but are there any plans to? Any idea if it's practical? For expanded polystyrene?
  - PaulHoule 3y ago
    That paper is not too remarkable, it's (1) the first one I found and (2) it uses extraordinarily mild conditions. The gap between the bench and a commercial factory is immense and there are many areas where people write papers like this for decades but nothing really gets built. I think the usual excuse is that the factory is large enough that it needs to gather waste over a huge area and that transportation of EPS is prohibitively expensive. It doesn't help that styrene monomer is worth only 50 cents a pound, about the same as gasoline.

PaulHoule 3y ago

Polystyrene is relatively easy to depolymerize with enzymes, catalysts and moderate amounts of heat, see https://pubs.acs.org/doi/10.1021/acssuschemeng.1c08400 https://pubs.acs.org/doi/10.1021/acssuschemeng.1c08400 The pyrolysis route they are using can be problematic because it produces carcinogenic aromatic compounds like https://en.wikipedia.org/wiki/Benzopyrene https://en.wikipedia.org/wiki/Benzopyrene which has a metabolite which is almost a cancer-causing drug. In principle you could pyrolyze plastics all the way down to carbon monoxide + hydrogen syngas and then build that up to molecules you want with C1 chemistry https://en.wikipedia.org/wiki/C1_chemistry https://en.wikipedia.org/wiki/C1_chemistry but most of the people who are trying chemical recycling by pyrolysis are trying to cook the molecules partially so the output fuel is a witches brew rich in hazardous aromatics. There is a lot of research into cleaner processes for chemical recycling such as https://www.nature.com/articles/s41598-021-83659-2 https://www.nature.com/articles/s41598-021-83659-2 and that one at the top but every large scale plant I've seen is a pyrolysis plant that's had to fight with environmentalists to start operations. From the viewpoint of a chemical engineer making fuel is for the birds because gasoline costs 50 cents a pound and (almost) any other chemical costs a lot more than that.

versteegen 3y ago
> Polystyrene is relatively easy to depolymerize with enzymes, catalysts and moderate amounts of heat Wow. The paper from 2022 so surely noone is using this process yet, but are there any plans to? Any idea if it's practical? For expanded polystyrene?
- PaulHoule 3y ago
  That paper is not too remarkable, it's (1) the first one I found and (2) it uses extraordinarily mild conditions. The gap between the bench and a commercial factory is immense and there are many areas where people write papers like this for decades but nothing really gets built. I think the usual excuse is that the factory is large enough that it needs to gather waste over a huge area and that transportation of EPS is prohibitively expensive. It doesn't help that styrene monomer is worth only 50 cents a pound, about the same as gasoline.