4 ms·

The journal article is open access. https://pubs.rsc.org/en/content/articlelanding/2025/gc/d4gc05916f https://pubs.rsc.org/en/content/articlelanding/2025/gc/d4g

by kibibu 2y ago

The journal article is open access. https://pubs.rsc.org/en/content/articlelanding/2025/gc/d4gc05916f https://pubs.rsc.org/en/content/articlelanding/2025/gc/d4gc0... > Catalytic amounts of AC/MoO2 selectively convert waste PET into its monomer, terephthalic acid (TPA), within 4 h at 265 °C with yields as high as 94% under 1 atm air. I'm not a chemist so don't know if you can find a way to calculate the cost, but the authors claim that it's cheaper than current methods. The bigger deal imo is that it recovers PET monomers from mixed plastics, which means avoiding manufacturing more plastic.

projektfu 2y ago
Yeah, these are pizza oven temperatures. The temperature appears to be just above the melting point for PET. It is also in the liquid phase for PBT, PEN and PEF. I think most recycling methods for PET require melting anyway.
- stubish 2y ago
  Also manufacturing, so importantly this might be more energy efficient and maybe even cheaper than making new plastic. Depending on how the monomer->PET part gets solved.
PaulHoule 2y ago
This is contrast to the pyrolysis-based "chemical recycling of plastics" which makes a mix of petrochemicals similar to what you find in the BTX stage of a petrochemical factories [1], especially for condensation polymers like PET. That is, this process produces fairly pure Terephthalic acid [2] and Acetaldehyde [3] and the first of those could be recycled into more PET. The thing is BTX chemicals and other precursors of mass produced plastics cost about 50 cents a pound which makes it hard for any kind of recycling process to be competitive. [1] https://en.wikipedia.org/wiki/BTX_(chemistry) https://en.wikipedia.org/wiki/BTX_(chemistry) [2] https://en.wikipedia.org/wiki/Terephthalic_acid https://en.wikipedia.org/wiki/Terephthalic_acid [3] https://en.wikipedia.org/wiki/Acetaldehyde https://en.wikipedia.org/wiki/Acetaldehyde
- culi 2y ago
  > about 50 cents a pound which makes it hard for any kind of recycling process to be competitive. We've had almost a century of subsidization of the oil industry. The gov't needs to play a bigger similar role if the recycling industry is ever gonna be able to compete We need a tax on the full lifecycle cost of plastics so we can stop treating waste as an economic externality
  - PaulHoule 2y ago
    Landfilling plastics on the other costs about 4 cents a pound. The nightmare scenario about plastics is not that they get landfilled but that people chuck them on the ground and they find their way to the ocean and get ground up into microplastics.
    - Gigachad 2y ago
      Or that they just shed microplastics during their lifetime. Car tires and clothing being a huge source. It would be cheaper to just ban stuff like polyester fleece than to try to clean it up after.
      - timschmidt 2y ago
        Or we could price cleanup and recycling of the constituent materials into the purchase price by requiring manufacturers to pay to recycle all the items they manufacture. This approach closes the loop in a way which encourages manufacturers to re-engineer their products to be less expensive to recycle.
        Gigachad 2y ago
        Cleanup is impossible though. How are you going to clean up a trillion nanoplastic dust particles? What is the effective difference between phasing out fleece clothing vs charging $100M for a jacket?
        2y ago
jandrese 2y ago
That's within the range of a kitchen oven. The biggest problem is that plastic is so cheap that even that relatively modest energy use may make it uneconomic compared to virgin TPA, especially if you have to clean the inputs thoroughly first.
- roughly 2y ago
  In fairness, that’s mostly because current plastic production externalizes the cost of everything about the lifecycle before and after manufacturing and use.
  - hinkley 2y ago
    Tariff on virgin, and at least half the same for recycled material.
hinkley 2y ago
4 hours sounds like a lot of factory space to generate a substantial flow of output.
- ta988 2y ago
  Those processes can be made continuous most of the time.
  - hinkley 2y ago
    You've still got Little's Law though. You either need a very giant machine or a very low feed rate in order to have stuff come out one end 4 hours after going in the other. I think steel recycling may be faster than that.
alhw 2y ago
The authors' claim is that it is cheaper than other catalytic methods that have been explored/invented to depolymerize PET into TPA monomers. These qualitative cost estimates are based on the reaction conditions (temperature, solvent, other reactants (in this case, humid air)) and the unit operations involved in the downstream separation processes that isolate the TPA product from unreacted PET. The largest hurdle that precludes widespread deployment of technologies for PET recycling, as well as those for most other plastics, occurs (way) upstream of the reaction and separation train. The highest cost is related to collecting and sorting used PET bottles and TPA-derived textiles. Mechanical recycling or any flavor of chemical recycling (pyrolysis, hydrolysis, etc.) all suffer from the same hurdle. If the target product of the recycling process is a TPA-derived plastic (be it for clothing or soda bottles), then mechanical recycling is usually cheaper, since it produces a product that only needs to be reshaped and remolded to give shirts or jugs. Chemical recycling converts PET into its constitutive monomers, and to (re)produce a TPA-derived plastic from the monomers requires a not inexpensive (re)polymerization step, in addition to reshaping and remolding. Chemists, even highly regarded ones like Tobin Marks, are less interested in "solving" the PET recycling issue and more interested in the fundamental chemistry involved in chemical recycling. Issues of Green Chemistry (or blurbs in phys.org) are not the appropriate reading materials to get insight into costs, scale-up, etc.. Very few, if any, academic journals are focused on such matters, and rightly so, in my opinion.

by kibibu 2y ago

projektfu 2y ago

Yeah, these are pizza oven temperatures. The temperature appears to be just above the melting point for PET. It is also in the liquid phase for PBT, PEN and PEF. I think most recycling methods for PET require melting anyway.

stubish 2y ago
Also manufacturing, so importantly this might be more energy efficient and maybe even cheaper than making new plastic. Depending on how the monomer->PET part gets solved.

PaulHoule 2y ago

This is contrast to the pyrolysis-based "chemical recycling of plastics" which makes a mix of petrochemicals similar to what you find in the BTX stage of a petrochemical factories [1], especially for condensation polymers like PET. That is, this process produces fairly pure Terephthalic acid [2] and Acetaldehyde [3] and the first of those could be recycled into more PET. The thing is BTX chemicals and other precursors of mass produced plastics cost about 50 cents a pound which makes it hard for any kind of recycling process to be competitive. [1] https://en.wikipedia.org/wiki/BTX_(chemistry) https://en.wikipedia.org/wiki/BTX_(chemistry) [2] https://en.wikipedia.org/wiki/Terephthalic_acid https://en.wikipedia.org/wiki/Terephthalic_acid [3] https://en.wikipedia.org/wiki/Acetaldehyde https://en.wikipedia.org/wiki/Acetaldehyde

culi 2y ago
> about 50 cents a pound which makes it hard for any kind of recycling process to be competitive. We've had almost a century of subsidization of the oil industry. The gov't needs to play a bigger similar role if the recycling industry is ever gonna be able to compete We need a tax on the full lifecycle cost of plastics so we can stop treating waste as an economic externality
- PaulHoule 2y ago
  Landfilling plastics on the other costs about 4 cents a pound. The nightmare scenario about plastics is not that they get landfilled but that people chuck them on the ground and they find their way to the ocean and get ground up into microplastics.
  - Gigachad 2y ago
    Or that they just shed microplastics during their lifetime. Car tires and clothing being a huge source. It would be cheaper to just ban stuff like polyester fleece than to try to clean it up after.
    - timschmidt 2y ago
      Or we could price cleanup and recycling of the constituent materials into the purchase price by requiring manufacturers to pay to recycle all the items they manufacture. This approach closes the loop in a way which encourages manufacturers to re-engineer their products to be less expensive to recycle.
      - Gigachad 2y ago
        Cleanup is impossible though. How are you going to clean up a trillion nanoplastic dust particles? What is the effective difference between phasing out fleece clothing vs charging $100M for a jacket?
        2y ago

jandrese 2y ago

That's within the range of a kitchen oven. The biggest problem is that plastic is so cheap that even that relatively modest energy use may make it uneconomic compared to virgin TPA, especially if you have to clean the inputs thoroughly first.

roughly 2y ago
In fairness, that’s mostly because current plastic production externalizes the cost of everything about the lifecycle before and after manufacturing and use.
- hinkley 2y ago
  Tariff on virgin, and at least half the same for recycled material.

hinkley 2y ago

4 hours sounds like a lot of factory space to generate a substantial flow of output.

ta988 2y ago
Those processes can be made continuous most of the time.
- hinkley 2y ago
  You've still got Little's Law though. You either need a very giant machine or a very low feed rate in order to have stuff come out one end 4 hours after going in the other. I think steel recycling may be faster than that.

alhw 2y ago

The authors' claim is that it is cheaper than other catalytic methods that have been explored/invented to depolymerize PET into TPA monomers. These qualitative cost estimates are based on the reaction conditions (temperature, solvent, other reactants (in this case, humid air)) and the unit operations involved in the downstream separation processes that isolate the TPA product from unreacted PET. The largest hurdle that precludes widespread deployment of technologies for PET recycling, as well as those for most other plastics, occurs (way) upstream of the reaction and separation train. The highest cost is related to collecting and sorting used PET bottles and TPA-derived textiles. Mechanical recycling or any flavor of chemical recycling (pyrolysis, hydrolysis, etc.) all suffer from the same hurdle. If the target product of the recycling process is a TPA-derived plastic (be it for clothing or soda bottles), then mechanical recycling is usually cheaper, since it produces a product that only needs to be reshaped and remolded to give shirts or jugs. Chemical recycling converts PET into its constitutive monomers, and to (re)produce a TPA-derived plastic from the monomers requires a not inexpensive (re)polymerization step, in addition to reshaping and remolding. Chemists, even highly regarded ones like Tobin Marks, are less interested in "solving" the PET recycling issue and more interested in the fundamental chemistry involved in chemical recycling. Issues of Green Chemistry (or blurbs in phys.org) are not the appropriate reading materials to get insight into costs, scale-up, etc.. Very few, if any, academic journals are focused on such matters, and rightly so, in my opinion.