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Author: Subject: pyrolysis of plastic and plastic products
xfusion44
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[*] posted on 11-10-2014 at 15:32


@Oxirane

Thanks for that information :)

I have a question: when you decompose PET, by heating, does it also release HCl gas, like when you burn it? And if it does, could I use it, to make some strong HCl acid, by bubbling it through water?




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Little_Ghost_again
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[*] posted on 11-10-2014 at 15:41


http://en.wikipedia.org/wiki/Polyethylene_terephthalate

I have PET, so will give this a shot and see if I get what you do, its a recycle of 1 so that means it might be worth the effort.
Looks like crystals are to be expected, I have other things going on experiment wise so I cant give much time to it, but I can try and see if its worth trying to get fuel.
At some point soon I might be able to give you MUCH more info ;).
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xfusion44
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[*] posted on 11-10-2014 at 21:31


Ok, thanks :)

What kind of apparatus will you use for pyrolysis? Do you already have something, or do you need to build something?




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Little_Ghost_again
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[*] posted on 12-10-2014 at 01:57


I will probably start small in a boiling tube and bubble into a water bath with a upturned gas jar, if that goes ok then scale up to a 2 Ltr conical flask again into a water bath and large gas jar.
If I get anything similar to yours I will try and fractionate it into test tubes with 1C increments depending.
I also have TLC plates so they might be worth a shot.
We recycle milk bottles so have a stack of them at the moment.
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blogfast25
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[*] posted on 12-10-2014 at 03:30


Quote: Originally posted by xfusion44  
I have a question: when you decompose PET, by heating, does it also release HCl gas, like when you burn it? And if it does, could I use it, to make some strong HCl acid, by bubbling it through water?


It doesn't contain significant amounts of chlorine, so no.




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xfusion44
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[*] posted on 12-10-2014 at 04:28


Quote: Originally posted by blogfast25  
Quote: Originally posted by xfusion44  
I have a question: when you decompose PET, by heating, does it also release HCl gas, like when you burn it? And if it does, could I use it, to make some strong HCl acid, by bubbling it through water?


It doesn't contain significant amounts of chlorine, so no.


Ok, thanks :)




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xfusion44
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[*] posted on 12-10-2014 at 04:29


Quote: Originally posted by Little_Ghost_again  
I will probably start small in a boiling tube and bubble into a water bath with a upturned gas jar, if that goes ok then scale up to a 2 Ltr conical flask again into a water bath and large gas jar.
If I get anything similar to yours I will try and fractionate it into test tubes with 1C increments depending.
I also have TLC plates so they might be worth a shot.
We recycle milk bottles so have a stack of them at the moment.


Can't wait for your report :)




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aga
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[*] posted on 27-10-2014 at 12:10


I finally got my 10 gallon pyrolysis rig set up, and working.

The rocket stoves didn't work (5 at once).
Welding up a grate and simply making a wood fire under the tank got the interior to > 300 C.

For the first run, i used some weeds, which are in plentiful supply hereabouts.

Syngas was (presumably) the gaseous product, as it burned rather well, and with hardly any colour.

Is there anything to be Done with syngas other than just burning it ?




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blogfast25
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[*] posted on 27-10-2014 at 12:28


Quote: Originally posted by aga  
Is there anything to be Done with syngas other than just burning it ?


Have you tried condensing some of it?




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aga
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[*] posted on 27-10-2014 at 13:10


i added a Cold Finger to the end of the piping, with cold-ish water running thru it.

Still 24~28 C+ here all day. The water was probably around 15~18C (Brrrr !).

*some* brown stuff aggregated on the glass as it entered the cold finger thing, and the escaping syngas/smoke was neither hot nor cold to the touch.

Edit:

I Caught a litre of it to play with.

[Edited on 27-10-2014 by aga]




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[*] posted on 27-10-2014 at 13:28


Might be easier if you see what Advanced Technological Apparatus is deployed here.

rig.JPG - 209kB

Yes, the blue and white tub is full of water and about 5 feet of copper pipe as a condenser.

[Edited on 27-10-2014 by aga]




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blogfast25
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[*] posted on 28-10-2014 at 05:27


Anyroads, enough with torturing weeds. Next up, uPVC? I'd really like some benzene produced from PVC pyrolysis...



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plante1999
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[*] posted on 28-10-2014 at 06:15


Many plastic are reputed to produce benzene upon pyrolysis, but it is really dependant on the temperature.
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[*] posted on 28-10-2014 at 10:49


Any clues about the most favourable temperature to convert PVC to Benzene & HCl ?

While we're at it, how about an efficient way to absorb the HCl in water ?

Current thoughts are to condense the benzene in the bucket-condenser (with a shorter pipe from the pyrolysis tank) and then try to dissolve the HCl in very cold water, whilst avoiding suck-back.

I have a small Test lump of PVC (247g) which calculates out to give a max of ~4 mol HCl = 88 Litres of gas (!).

The HCl Gas is my main concern, and a gas mask will be on hand, maybe on face.




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blogfast25
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[*] posted on 28-10-2014 at 13:07


Quote: Originally posted by aga  
While we're at it, how about an efficient way to absorb the HCl in water ?

The HCl Gas is my main concern, and a gas mask will be on hand, maybe on face.


Just about any way will due to the very high solubility of the HCl gas in water.

When I did a HCl generator once (H2SO4 + NaCl) I lead the gas directly through water with a tube. What was interesting was that no bubbles where ever formed: at the outlet of the tube the gas was directly dissolved into the water without any bubbles forming! You just can't go wrong. Trust me, no gas mask is needed.

But do use an anti-backsuction device, between pyrolysatorix and HCl absorption unit. Lead the gas into an empty vessel first, then back out and into the water. This way, if there's an unexpected pressure drop on the reactor side, only a bit of the water will be sucked into the anti-backsuction device, and not all the way into the pyrolyser.

[Edited on 28-10-2014 by blogfast25]




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Oxirane
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[*] posted on 28-10-2014 at 13:21


The gas evolvement rate may become so high that it can heat up the water and at extreme restrict the solution rate to 20%. I got into slight trouble with that at 1 liter suction flask which heated way up, but I had insulated reactor and powerful propane burner so slowing down will solve the issue. Slower rates such as faced in the HCl+H2SO4 or NaHSO4 generator are very easy to handle and as blog said, there will be very little if no bubbling at all.
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[*] posted on 28-10-2014 at 14:16


Pyrolyzing nitriles can produce quite substantial amounts of hydrogen cyanide.

One gram of polyacrylonitrile (PAN) burned (not pyrolyzed) in a 15.6-liter combustion chamber created a cyanide concentration of 1500 ppm (lethal in 1-2 minutes).

http://www.ncbi.nlm.nih.gov/pubmed/6315551

Cyanide poisoning has become a major contributor to fire deaths. ("Smoke inhalation" deaths are not due to smoke particles, but are due to CO, HCN and thermal injury.)
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[*] posted on 28-10-2014 at 15:03


HCN production in Combustion or Pyrolysis ?

I think it's Combustion.

Yes, way too much 'plastic' around these days, so it's time to fight back and convert it all to useful reactants.

Call Captain Pyrolysis !

It might seem hard to get a Sofa into a 10 gallon tank through a 4" hole.
All you need to do is light a match in the tank, and push part of the sofa into the hole.
It worked for the Boiled Egg in a Bottle trick !

If the dissolution rate of HCl is *that* high, i suppose i'd better get rid of as much water as possible from the apparatus first.




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plante1999
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[*] posted on 28-10-2014 at 15:08


I had chart for the temperature back then, but I lost them.

If I may say, HCl should not be a problem, simply let it go over water in a flask..
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[*] posted on 28-10-2014 at 15:10


Quote: Originally posted by blogfast25  
Anyroads, enough with torturing weeds. Next up, uPVC? I'd really like some benzene produced from PVC pyrolysis...
It may be Good if i were to have some Test that shows that Benzene had been produced - a way to Know it was Benzene.



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plante1999
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[*] posted on 28-10-2014 at 17:01


I have a test which use oleum, but I think it may not be for you.. You can also make nitrobenzene to test it.
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blogfast25
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[*] posted on 29-10-2014 at 05:41


Quote: Originally posted by aga  
]It may be Good if i were to have some Test that shows that Benzene had been produced - a way to Know it was Benzene.


Smell is quite characteristic (I can send you a sample, if you like), once you've smelled it you'll understand the meaning of the term 'aromatic compounds'. BP and MP (the latter is 5.5 C, thus easy to verify).

Cheap and colourful test for benzene I do not know of.

Quote: Originally posted by aga  
If the dissolution rate of HCl is *that* high, i suppose i'd better get rid of as much water as possible from the apparatus first.


Yes. Use the condenser first to eliminate low boilers like water, benzene et al. Then lead the cooled gas through the anti-suck-back and through the water to capture the HCl that wasn't condensed.

But if your starting product is dry and there's little oxygen you can't get a lot of water in the pyrolysis products anyway.


[Edited on 29-10-2014 by blogfast25]




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[*] posted on 29-10-2014 at 12:23


Test run done with 237g of uPVC.

The 'rig' was washed out as best it could be after the Wood pyrolysis, yet some black goop remained in the tank.

I assume Benzene smells like Diesel fuel.
If not, i made Diesel Fuel and not Benzene.

Plenty of HCl produced.
To even weigh the assumed benzene, the gas mask came out.
It Fumes horribly, whiffing of HCl and more complex smells, similar to Diesel.

Several Leaks in the rig, from which quite a lot of HCl escaped, presumably other products too.

All data in the attached excel file.

Leaks will be fixed, and a few Kgs of PVC attempted next run.


Attachment: Data.xlsx (11kB)
This file has been downloaded 382 times

IMG_0192.JPG - 302kBIMG_0194.JPG - 266kBIMG_0196.JPG - 141kBIMG_0201.JPG - 161kB




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plante1999
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[*] posted on 29-10-2014 at 13:08


Distill and get a BP.
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[*] posted on 29-10-2014 at 13:21


There's about 8ml of brown stuff, full of HCl too.

Would there be enough Gas to even heat up the 250ml RBFs i have, let alone the thermometer ?

Perhaps i should vac the HCl off first, and distill the leftover 3g of benzene-maybenot afterwards.

I can see now where a micro-scale disty rig would be useful.

Edit:

It should be mentioned that the 5L Benzene collecting bottle had Pink liquid droplets on the inside.
Maybe the Seal on the valve got dissolved.

I will check tomorrow, and post pictures of the post-trauma PVC.

[Edited on 29-10-2014 by aga]




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