r/science Oct 06 '22

A new chemical process can break down a variety of plastics into usable propane - a possible solution to our inability to effectively recycle many types of plastic. Chemistry

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722 Upvotes

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61

u/sumrz Oct 06 '22

It seems like stories about these types of solutions to plastics come out every so often, but are they ever implemented anywhere. I’ve heard about bacteria that eats oil/plastic/whatever or ways to convert bad plastic into better plastic but I never hear anything after these stories are reported. Do oil companies buy and shelve the patents for the processes or what?

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u/sup299 Oct 06 '22

A lot of these novel processes work in the lab but are very difficult to scale to larger volumes, or the process is inefficient enough that the impact on pollutants is comparable to or worse than standard refining methods. This process is one that likely could scale successfully, and if it’s being studied by NREL and backed by the BOTTLE Consortium it has a pretty good chance of succeeding. It’ll still take time to implement, there are tons of logistics and engineering to work out.

Oil companies aren’t necessarily shelving these technologies, and they’ve taken a lot more interest in the last 7 or so years due to public pressure, but there is still so much money for them to make from normal extraction and processing methods that they leave adoption of these technologies to less powerful wings of their companies. Once they commercialize a new tech they’ll make it their entire brand, but because of the enormous scale of the oil and chemicals industry these green solutions are just a drop in the bucket in terms of total extraction, processing, and consumption.

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u/rawbdor Oct 07 '22

You seem smart so I'd like to ask a question. A lot of these ideas to break down plastics seem to center on turning it into some type of usable fuel, which sounds great but, doesn't that just mean we are taking all the carbon and..... Shitting it out into the air? We aren't sequestering the carbon, or using it to feed plants or get it locked up in some nice big trees. We are just shitting it out into the air with extra steps. Turn it into fuel, use the fuel...

Am I wrong about this?

4

u/wherearemypockets Oct 07 '22

Although this is not completely wrong, it’s also not completely correct.

A lot of these technologies produce an oil like substance by breaking down plastics that can be reprocessed into fuels and / or raw chemicals (such as propane or ethane) to be turned into plastic again. The split between fuel and plastic production depends on where the oil like substance is being reprocessed which is dependent on the contamination. It should also be noted that there are technologies in this area that break down plastics only into plastic monomers to be made into plastics. The plastic feedstock for these technologies are generally more restricted than the generic mixed plastic waste, such as only PET.

What is novel about this technology is the catalyst being able to break down the plastic into propane instead of an array of molecules (C1 - C20+). This means the majority of the end product can be sent to make plastic again (a bigger split to plastic production vs fuels is possible for every molecule of plastic).

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u/ElectricNed BS|Engineering|Materials Joining Oct 07 '22

You're not wrong. It's a way to get two uses out of hydrocarbons instead of just one. Two is better than one. Better is good. We need to get to zero fossil fuels, but since we are so far off from that goal, improvements we can get in the near term are worthwhile. We can't wait for perfection.

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u/No-Bother6856 Oct 07 '22

Well idk about that. If the goal is carbon sequestration, it seems to me that carbon stuck in plastics for thousands of years is better than burning it.

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u/ElectricNed BS|Engineering|Materials Joining Oct 07 '22 edited Oct 07 '22

We can't stop burning stuff tomorrow or next year. We need to, but it will take time. Extracting fossils twice for two uses is more harm than extracting it once for two uses. I work in electrification - believe me when I say I am 100% in on stopping burning stuff- but it's not going to taper down that fast.

Plastics aren't going into long term sequestration anyway. Plastic is uneconomic to recover now and it's going into oceans and ecosystems instead of reuse. Making more pathways for economic reuse keeps more plastic out of the environment and results in less oil extraction. Seems like a win to me.

1

u/skaterjuice Oct 07 '22

Excuse my huge oversimplification, but the carboniferous period was such a carbon sink because nothing could use all that plant matter as energy and emit it back into the atmosphere. It got buired and became coal, oil etc. It's probably better to bury the plastic than to burn it no? I often joke this is the platiciferous period.

I suppose we will be pulling new hydrocarbons out of the earth to burn anyway. Extraction has high emissions. So maybe burning hydrocarbons that are at the surface might be better (since we are burning hydrocarbons not because they are there but because we have chosen that method of fueling a piece of equipment)

1

u/dancintoad Oct 07 '22

The plastics are ending up in the soil, food chain and our bodies. Not to mention the ocean. This sounds like An Option not the whole ball of wax. If anyone still collects wax.

1

u/n3w4cc01_1nt Oct 06 '22

the end products expensive and people want cheap fuel. if they made a market for it I'm sure people with mopeds would buy the fuel since they get 200mpg.

1

u/AtomicPyroX Oct 06 '22

It seems the question is always, does it scale. And not only that would it scale to process 100’s to 1000’s of tons per day.

9

u/Hyjynx75 Oct 06 '22

It's often because the process costs more to implement than just making new plastic.

I watched a TED talk once where they talked about implementing a tax on new raw plastic to make recycling techniques more attractive to industry.

https://www.ted.com/talks/andrew_forrest_a_radical_plan_to_end_plastic_waste?language=en

3

u/diagnosedwolf Oct 06 '22

The problem is making the byproduct worth the cost. The bacteria, for instance, are pretty useless at creating anything we can reuse. They just break down oil or plastic. That’s great if that’s your goal, but catastrophic if they were to be unleashed in the environment generally. After all, imagine bacteria eating the plastic parts of your house or car. Of your ventilator.

They do use bacteria during oil spills. You’ll see footage of people with tanks strapped to their backs spraying a clear fluid onto oil-slicked rocks and stuff. That’s the oil-eating bacteria being spread about to clean up.

1

u/YaMamSucksMeToes Oct 07 '22

I thought that clear fluid was just soap

3

u/diagnosedwolf Oct 07 '22

Soap works by creating a small bubble around oil and dirt. It can do this because it is bipolar, with a hydrophobic end and a hydrophilic end. Oil is hydrophobic, so it ends up clustered near the hydrophobic end of the soap, which arranges itself into a sphere all the way around the oil.

The outside of this little bubble can be carried away by water. That’s why we use soap and water - soap by itself doesn’t work.

What this means is if you just used soap on an oil slick, it would basically just dissolve the oil into the water. Instead of the oil floating on top of the water, it penetrates deep below the surface and poisons a far greater number of marine organisms.

1

u/MD4LYFE Oct 07 '22

Why do you think oil companies would want to stop this type of technology? They'd love for their products to be more sustainable. It would be a major boon to them.

6

u/Maharsi Oct 06 '22

40bar at 523k for <80h for 25cm3 chamber with cobalt based catalyst.

That's quite a bit of energy for a little amount, currently, could net more productively with more research.

5

u/kkngs Oct 07 '22

Couldn’t we just bury the plastic somewhere geologically stable (e.g. Nevada) and call it carbon sequestration?

3

u/1heart1totaleclipse Oct 07 '22

I don’t think Nevada is big enough for all the trash we have

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u/kkngs Oct 07 '22

It easily is. The whole “running out of space in landfills” thing from the early 90s was bs, there was just a temporary shortage of new landfills being opened due to economic and permitting issues.

The real failure of my suggestion is that the cost and CO2 footprint of transporting all that plastic is likely worse than just burning it.

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u/[deleted] Oct 06 '22

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u/jefflovesyou Oct 07 '22

That is some good news, I tell you hwhat.

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u/allbright1111 Oct 07 '22

I was going to say that Hank Hill must be so happy right now.

2

u/nadmaximus Oct 07 '22

Many propane accessories are made of plastic. We can close the cycle.

4

u/[deleted] Oct 06 '22

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3

u/muskoka83 Oct 07 '22

Scenario: Imagine a massive rush to collect all the trash plastic from the ocean now because it's valuable. Planet thrives because of greed.

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u/[deleted] Oct 06 '22

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0

u/blackhornet03 Oct 07 '22

If a plastic is not easily recycled we should not make it.

1

u/allbright1111 Oct 07 '22

“Should” statements aren’t super helpful when the action has already taken place. I support scientific endeavors to deal with the problems we actually have.