[HN Gopher] Scientists break down plastic using a simple, inexpe...
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Scientists break down plastic using a simple, inexpensive catalyst
and air
Author : PaulHoule
Score : 54 points
Date : 2025-03-21 20:12 UTC (4 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| kikokikokiko wrote:
| Well, they used a "simple, inexpensive catalyst" and then HEATED
| the plastic/catalyst mysture. Nowhere in the article it gives you
| an estimate of the final cost of the process.
| IAmBroom wrote:
| Yes. I can break down plastics that way, using ordinary tap
| water.
|
| Actually, the tap water is optional.
|
| And instead of monomers, the end product is carbon - which is
| even more recyclable!
| kibibu wrote:
| The journal article is open access.
| 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
| degC 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 wrote:
| 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.
| PaulHoule wrote:
| 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)
|
| [2] https://en.wikipedia.org/wiki/Terephthalic_acid
|
| [3] https://en.wikipedia.org/wiki/Acetaldehyde
| culi wrote:
| > 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 wrote:
| 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.
| jandrese wrote:
| 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 wrote:
| In fairness, that's mostly because current plastic
| production externalizes the cost of everything about the
| lifecycle before and after manufacturing and use.
| hinkley wrote:
| Tariff on virgin, and at least half the same for recycled
| material.
| hinkley wrote:
| 4 hours sounds like a lot of factory space to generate a
| substantial flow of output.
| ta988 wrote:
| Those processes can be made continuous most of the time.
| kylehotchkiss wrote:
| I was expecting a much more complicated catalyst!
| wolfi1 wrote:
| there is also the possibility to recycle pet-bottles into food
| grade bottles again using just mechanical means, I know at least
| two European companies who provide such machines
| PaulHoule wrote:
| I've seen 100% recycled PET bottles for Coca-Cola products in
| the US
|
| https://www.cnn.com/2024/03/19/food/coca-cola-new-bottles/in...
|
| and Pepsi is selling 100% post-consumer bottles in some EU
| countries
|
| https://www.pepsico.com/our-stories/press-release/pepsico-co...
|
| Those clear beverage containers are an ideal case for
| mechanical recycling. This company
|
| https://repreve.com/
|
| makes polyester fiber from recycled PET. I have a few garmets
| made from it and my impression is that the fabric feel is nicer
| than average.
| culi wrote:
| Yes PET (#1) and HDPE (#2) are the two easiest plastics to
| recycle and the most commonly recycled
| Xiol32 wrote:
| Break down into what? Is this also going to end up in my
| testicles?
| __MatrixMan__ wrote:
| terephthalic acid and acetaldehyde (the paper: https://pubs.rsc
| .org/en/content/articlehtml/2025/gc/d4gc0591...)
| tigerBL00D wrote:
| It says "Leveraging the trace amounts of moisture in air, the
| broken-down PET is converted into monomers--the crucial
| building blocks for plastics. From there, the researchers
| envision the monomers could be recycled into new PET products
| or other, more valuable materials." I don't know if there's
| some enormous challenge hiding behind the word "envision", but
| I'm assuming it's a closed system until something useful comes
| out of the other end. The method just can't be a lot more
| expensive than to make the same thing/material from scratch or
| it's never going to gain traction.
| Imustaskforhelp wrote:
| Well let's truly hope that its not that much expensive
| culi wrote:
| What percentage is actually broken down into monomers? How much
| microplastic waste is left behind. Given the reliance on "ambient
| air" I imagine it's not 100%.
|
| Regardless, I'm excited to hear about progress on solving the
| plastic waste crisis. It seems better than the current
| alternatives the article presents:
|
| > "The U.S. is the number one plastic polluter per capita, and we
| only recycle 5% of those plastics," said Northwestern's Yosi
| Kratish, the study's co-corresponding author. "There is a dire
| need for better technologies that can process different types of
| plastic waste. Most of the technologies that we have today melt
| down plastic bottles and downcycle them into lower-quality
| products.
| culi wrote:
| This is great but PET (symbol #1) is one of the few plastics that
| ARE recyclable. I wonder if any of these techniques can be used
| to solve the non-recyclable plastic problems
| iwontberude wrote:
| Not infinitely so, maybe this is used on old PET
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