Sciencemadness Discussion Board - pyrolysis of plastic and plastic products

Seems that the pyrolysis products of PVC vary wildly with pressure.

Precis:
http://www.sciencedirect.com/science/article/pii/S0141391003...

Paper:
https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/42_...

[Edited on 27-9-2014 by aga]

Oxirane - 28-9-2014 at 00:05

So it's essentially an effective and OTC source of benzene and HCl.

aga - 28-9-2014 at 01:54

*If* you got a metal pot and some copper pipe.

I think metal pots are List II, copper pipe List I.

Oxirane - 28-9-2014 at 03:04

Dont worry, I've got mine.

I just tested this thing. I cut up some pvc tubing into steel pot, lead a distill bridge into receiver flask and gas tube to water trap. After the tube got hot, receiver filled with chlorine coloured gas and bubbles came through the water trap. The gas production came more intense when heat built up, so I had to relieve it a little, and the liter of cold water got hot and I got to make own cold bath for it. Eventually more HCl was released what the water could handle, so I had to stop the reaction. pH paper gave very dark red. The whole reaction took no more than half an hour. The downside is that the HCl solution in this setup got greenish tint and some solid impurities in it. I think this could be avoided by cooling the receiver and installing a reflux column to it to condense all the solids.

The reaction also releases a lot of noxious and thick fumes and one may need to build two water traps back to back and make sure that all connections and threads etc. are thightly closed. I made my reaction outside and yet there was quite a stench.

So it can be said that PVC is very efficient OTC source of HCl, but some special equipment is needed to utilize it. I still got to open the pot and see how grimy it has become and if there is any corrosion. I believe it's quite a view.

[Edited on 28-9-2014 by Oxirane]

blogfast25 - 28-9-2014 at 03:54

Oxirane:

If I recall well (note caveat) concerns have been raised about the pyrolysis of PVC yielding dioxins. You may want to research that before going much further.

Eventually more HCl was released what the water could handle, so I had to stop the reaction. pH paper gave very dark red.
[Edited on 28-9-2014 by Oxirane]

With a maximum attainable concentration of 37 w% the amount of water needed to absorb the 'theoretical amount' of HCl should be easy to estimate.

[Edited on 28-9-2014 by blogfast25]

The generation of dioxins is related to the combustion (incineration) of PVC bearing household waste.

http://en.wikipedia.org/wiki/Polyvinyl_chloride#Dioxins

[Edited on 28-9-2014 by blogfast25]

Oxirane - 28-9-2014 at 05:26

Oh well thanks, now I'm sitting here shit scared and waiting for the symptoms of dioxin poisoning to show up...

Oxirane - 28-9-2014 at 07:32

http://rua.ua.es/dspace/bitstream/10045/12199/1/articulo%20c...

It seems that dioxins generally need oxygen at 400-700C to form. My reactor was closed from oxygen and the temperature decreased very quickly far below 400 before facing oxygenic environment. Even the distilling bridge was cool to hand touch.

On the page 6, if you mind to see the results, pyrolysis of PVC results only very little or no PCDD:s.

Think if Im going to continue pyrolysis tests I'll have to make an ejector chimney to blow all the remaining exhaust fumes up to the sky, make a larger condenser to condense all solids and wear complete safety gear when cleaning the parts.

This issue must be solved dead clear, because this sounds very good source of HCl. There must be way to complete it safely and cleanly.

[Edited on 28-9-2014 by Oxirane]

aga - 28-9-2014 at 13:50

Oxirane ! You Pioneering wonder !

I haven't even got my rig set up, and you got HCl !

Any Benzene apparent anywhere ?

Oxirane - 29-9-2014 at 00:57

Still alive, though dioxine will take 1-6 weeks to kill. Doh..

I only got very thick, heavy fuel oil - type residue, which I believe is a mixture of additives and benzene. Part of this residue came out and mixed to the HCl solution, which is because there was no actual condenser in use, only submerged receiver. HCl came out from the nozzle as a white, thick fume with extremely irritating smell, and mixed with it was greenish-brown gunk.

phlogiston - 29-9-2014 at 01:49

Pyrolysing rubber will yield Limonene in significant quantities:

http://www.sciencedirect.com/science/article/pii/S0165237000...

Full text available here

I doubt it'll smell as good as limonene made via other routes.

blogfast25 - 29-9-2014 at 04:10

http://rua.ua.es/dspace/bitstream/10045/12199/1/articulo%20c...

It seems that dioxins generally need oxygen at 400-700C to form. My reactor was closed from oxygen and the temperature decreased very quickly far below 400 before facing oxygenic environment. Even the distilling bridge was cool to hand touch.

From the structures it's clear oxygen would be needed to get dioxins from PVC. Anaerobic pyrolysis will yield a witches' brew (possibly with its own toxicity issues) without dioxins.

[Edited on 29-9-2014 by blogfast25]

Oxirane - 29-9-2014 at 05:29

That means there should be insignificant amounts of dioxins. I've got to clean the parts yet, gonna wear chemical industry grade respirator mask, gloves and maybe even protective suit. Bought those well ahead.

It would be good to make a topic for overall pyrolysis product, because many OTC stuff and even things considered garbage may yield some very interesting chemicals.

Polystyrene - styrene (and some toluene and benzene)
PVC - hydrogen chloride
Rubber - limonene
And so on.

TheChemiKid - 29-9-2014 at 06:49

UC has a good video on the pyrolysis of polystyrene: https://www.youtube.com/watch?v=6tEs7P6UUVQ

aga - 29-9-2014 at 07:15

Spurred on by Oxirane's attempt, i had a go at PVC pyrolysis today, using a 1L paint thinners tin, a rocket stove, and some copper pipe.

37.8g of PVC-B was cut from a PVC drainpipe coupler and put in the tin.
The outlet of the tin was taken via about 1m of 15mm dia copper pipe into exactly 1L of distilled water. The end of the pipe was underwater.

After 20mins, bubbles were seen leaving the pipe.
It was allowed to run for 1hr 30 mins.

The water is now rather acidic, turning UI paper red instantly.

A quick distillation of 200ml of the water gave a distillate at 95.5 C for 10 minutes.

The liquid left in the pot is still acidic, the distillate is neutral.
The distillate smells slightly sweet, but does not burn.

I was expecting gaseous HCl to be present, so had some damp UI paper in front of the vac adapter, but it remained neutral.

Allowing +/- 1 C around 95.5, that gives two azeotropes most likely:-
anisole / water (95.5 C) however insoluble in water ...
chloral / water (95.0 C)

Mightliy confusled.

[Edited on 29-9-2014 by aga]

The Acidity is around 0.08 [M] after a rough titration, and an even rougher Mohr's shows chlorides present.

[Edited on 29-9-2014 by aga]

blogfast25 - 29-9-2014 at 08:52

Aga:

Careful about suck back with that set up: water sucked back into the pyrolyser retort (the paint can, LOL) could be nasty (steam explosion). At a very minimum always get the tube out of the water before switching off the heat!

Assuming the 0.08 M to be correct, calculate how much of the PVC's chlorine ended up in the water as HCl. Did the water smell of anything?

If the pyrolyser is hot enough, organics should also come over and form a two layer system (but some will be gaseous). But if temperature is too low you might not be depolymerising the PVC just yet. The higher the temperature the jollier, within reason.

What does the PVC look like now?

Any idea of temperature inside the pyrolyser pot?

'Cracking' the backbone of this polymer requires fairly high temperatures, if you want it to proceed reasonably fast. The backbone is after all -C-C-C-C-C-C-, so highly stable. All these stable C-C covalent bonds...

[Edited on 29-9-2014 by blogfast25]

aga - 29-9-2014 at 09:16

On taking the rig to bits, a large volume of HCl escaped.
Clouds of it everywhere.

0.08[M] HCl collected roughly equals 13% of the available Cl extracted (2.84g / 21.44g).

Some of the PVC has disintegrated into fine black dust/grains.
A lot of it is still in a solid, porous, pliable mass, and looks black and shiny.
Definitely not PVC as we know it anymore.
Reminds me a lot of the shiny rock stuff in steel slag.

That lump wouldn't come out or break up, so i stuffed handfuls of dry weeds in with it to let it have another go.

I'd expect the temperature to about 300C ish in the pot.

Definitely need some bigger square steel section

blogfast25 - 29-9-2014 at 10:11

0.08[M] HCl collected roughly equals 13% of the available Cl extracted (2.84g / 21.44g).

Correct. And going by the escaped gas, considerably more.

Going by the rest, it looks like significant decomposition was achieved, but I'm surprised there didn't seem to be much condensable organic matter. Perhaps more time would achieve that.

Perhaps a cold trap after the HCl trap might also reveal more low boiling organics?

[Edited on 29-9-2014 by blogfast25]

aga - 29-9-2014 at 10:54

The idea was to use a 10 gallon steel tank and multiple burners, at least 2 condensers and some other stuff.

Oxirane beat me to it with his steel pot, so i *had*to rig this up and try it.

blogfast25 - 29-9-2014 at 11:06

Palavering a bit more, since as we're reasonably sure HCl comes off, the following structural rearrangement (HCl elimination reaction) must at least in part take place:

[-CHCl-CH2-]n --- > [-CH=CH-]n + n HCl

... giving rise to oligomeric structures like -CH=CH-CH=CH-CH=CH-CH=CH- etc.

Cyclisation of this conjugated structure could give rise to benzene and a plethora of other stuff, as suggested in the paper Oxirane linked to on the previous page.

[Edited on 29-9-2014 by blogfast25]

Oxirane - 29-9-2014 at 11:21

Gotta get you guys some pics on my setup next time I go to my workshop.

But my outcome was somewhat similar to aga's. The PVC was not much disintegrated and actually most part of it was quite intact. This is because I did not bring the process to an end but stopped it when there became those minor issues I mentioned. The vapor tube from the receiver which was PVC tubing got full of black tar and I was afraid of it blocking and causing burst from the receiver connector, and major amounts of HCl gas was released to atmosphere from the HCl water flask because of temp increase. This was quite un-scientific proof-of-concept-work in which I just dumped some PVC in and heated it up, but it gave the most important result: it does generate HCl and it does it in very good yield.

aga - 29-9-2014 at 11:28

Palavering a bit more, since as we're reasonably sure HCl comes off,

That it does !

Question is, What to chuck in there with the PVC to push the reaction(s) towards Benzene (or whatever) as well ?

blogfast25 - 29-9-2014 at 11:35

This could also be the object of a smaller, more quantitative lab test: boiling tube with PVC (heated by furnace of Bunsen), leading to small Liebig condenser, leading into anti-suck back trap (trapping also stuff like benzene), leading to HCl water trap, leading to cold trap.

blogfast25 - 29-9-2014 at 11:37

Question is, What to chuck in there with the PVC to push the reaction(s) towards Benzene (or whatever) as well ?

Something that favours cyclisation. Need to look at some catalysts for that...

aga - 29-9-2014 at 11:45

Iron wool, bits of verdigris-covered copper tube then !

blogfast25 - 29-9-2014 at 12:03

Iron wool, bits of verdigris-covered copper tube then !

Huh?

A starting point for choice of catalyst is to understand the cyclisation reaction itself better, of course.

[Edited on 29-9-2014 by blogfast25]

blogfast25 - 29-9-2014 at 12:21

One can try to imagine a possible cyclisation reaction as the bridging between carbon atoms 1 and 6, in 'badly drawn boy', here:

Can't be that hard, now cannit?

[Edited on 29-9-2014 by blogfast25]

aga - 29-9-2014 at 12:48

Nah. Lose some H and it's given.

What likes H more than C does, but isn't O or Cl ?
Oh yeah. OH.

So lob some NaOH in with the PVC ?

OH attack on pos 1 pushes electron density into the (left) CH, ejecting it, straining the ring, consequently rippling back and ejecting the CH on pos 6, leaving 1 and 6 nowhere to go but each other's open arms.

(I just made that up. It's unlikely to be reasonable, let alone true.)

Edit:

Forgot it's OC for second. All above fantasy via 10 intermediates.

[Edited on 29-9-2014 by aga]

blogfast25 - 30-9-2014 at 04:23

So lob some NaOH in with the PVC ?

An unusual way to prepare NaCl?

Last night I was doodling some more possible conformations of highly unsaturated, conjugated oligomers (residue from HCl elimination reactions) and came up with one that could be the most promising for cyclisation. Will upload tonight.

Any catalyst we throw in there had better be cheap because catalyst recovery from the gunk will be near impossible.

[Edited on 30-9-2014 by blogfast25]

aga - 30-9-2014 at 06:06

An unusual way to prepare NaCl?

Doh !

blogfast25 - 30-9-2014 at 06:28

Latest doodlings.

Imagine a longish stretch (at least 8 C atoms long) of PVC that has been subjected to HCl elimination reactions.

Imagine this now in the top conformation. By, erm, thermal rearrangement [cough!] atoms 1 and 6 could then link up to form benzene and more conjugated bonds are left in the part that was split off.

The dotted line between 2 and 5 represents the conjugated double bonds between 2 and 3 and between 4 and 5.

1 tentative mechanism for 1 compound, 49 or so to go!

[Edited on 30-9-2014 by blogfast25]

aga - 30-9-2014 at 11:04

Seems that in this polymer, the Position of the Cl is random, so randomly twisted chains would randomly allow two Cl to meet, possibly causing them to eject as Cl₂ , leaving the remaining C-H to latch on to other local C-H, occasionally forming Benzene, most times forming other stuff.

blogfast25 - 30-9-2014 at 11:48

Seems that in this polymer, the Position of the Cl is random, so randomly twisted chains would randomly allow two Cl to meet, possibly causing them to eject as Cl₂ , leaving the remaining C-H to latch on to other local C-H, occasionally forming Benzene, most times forming other stuff.

Possibly but it seems most chlorine leaves as HCl, not Cl2.

Also, you'd still have to break two strong C-Cl bonds, for instance:

-CH2-CHCl-CH2-(add some units)-CH2-CHCl- [twisted conformation] ===> Cl2 + cyclic compound

would have a positive ΔH, according to the bond enthalpies. The entropic term - TΔS would then have to save the day. It's not impossible, it just doesn't seem to happen much in reality.

[Edited on 30-9-2014 by blogfast25]

aga - 30-9-2014 at 13:28

Possibly but it seems most chlorine leaves as HCl, not Cl2.

.. you'd still have to break two strong C-Cl bonds ...

... would have a positive ΔH, according to the bond enthalpies.

[CH3Cl]n -> Sos + HCl

Perhaps the HCl is the most stable product that can be detected easily, and forms as a result of various intermediate reactions, of which there will probably be a great many.

The +ΔH is fine : we're pouring energy into this thing.

OC must be at least Partly guesswork to have gotten anywhere.
It's simply far too complex to be totally certain.

The PVC chain is 100s of 1000s of vinyl groups long.

How do OC chemists cope with thinking about the multitude of possible side reactions ?

Is this where NMR, GC etc became Required just to get a clue ?

blogfast25 - 1-10-2014 at 03:38

Another strong argument against Cl2 is the following. Take 1,6 dichlorohexane: Cl-(CH2

6-Cl. On heating it does not split off chlorine.

But use a Cl scavenger like an alkali metal and then:

2 K + Cl-(CH2

6-Cl === > (CH2

6 [cyclohexane] + 2 KCl becomes highly thermodynamically favourable (I'm not claiming this is a practical method to prepare cyclohexane, I don't know that).

(Don't try this at home: mixtures of haloalkanes and alkali metals are known to be explosively unstable!!)

Good point about the +ΔH!

Unravelling OC reaction mechanisms require some guess work, yes. More so here with this myriad of possibilities (see the paper Oxirane linked to for pyrolysis products of PVC).

All kind of analytical techniques can assist in solving the puzzle, including IR, GC, NMR and mass spectrometry (among others).

Perhaps the HCl is the most stable product that can be detected easily, and forms as a result of various intermediate reactions, of which there will probably be a great many.

We know from literature that the Cl is almost quantitatively recoverable but as HCl. Chlorine is also easy to detect (use nose but sparingly!)

[Edited on 1-10-2014 by blogfast25]

Little_Ghost_again - 1-10-2014 at 04:50

Really interesting way to get Hydrochloric acid! Great thread

aga - 1-10-2014 at 07:50

the Cl is almost quantitatively recoverable but as HCl. Chlorine is also easy to detect (use nose but sparingly!)

I must have been designed for OC as i have a Big nose (plenty of tests before dissolution)

Got a bloke making me 6 bigger burners for the 10 gallon tank.
Ready by Friday evening he says ...

blogfast25 - 1-10-2014 at 08:21

[Got a bloke making me 6 bigger burners for the 10 gallon tank.
Ready by Friday evening he says ...

Natural Gas? (I'm thinking of your BB...)

Oxirane - 1-10-2014 at 11:00

You might wanna go look for BBQ burners. Those bitches breath up to 6000 watts of heat. Remember also that insulating the reactor will significantly ease the heating. I use normal rockwool. Didnt remember to take pics.

Little_Ghost_again - 1-10-2014 at 13:36

Ok I am going to stop reading this thread now, I found some PVC pipe off cuts in a shed

. The temptation to have a go is increasing, so for the sake of safety I will follow no more

. good luck though, its a really neat way to do something with a waste product

aga - 1-10-2014 at 14:15

Insulation yes. Not Rockwool, but a star-wars-ti-fighter arrangement to duct the hot air.

It will certainly raise the 'reactor' temperature a bit.

I drilled a hole and welded a sealed stainless steel pipe into the 'reactor' so a thermometer can get in there - isn't Science with no measurements.

Least Fuel possible, hence the rocket stoves.

The Fuel can be the Reactant as well.

Collect some twigs, burn some, pyrolyse the rest.
Temptation is to pyrolise a few kg PVC, but wood seems more interesting (got enough HCl at the mo).

Weight the Total mass, split it into Reactants and Fuel, all weighed, then see what the results are.

All Good. Roll on Saturday.

Quick Vote : pyrolise Wood or PVC first ?

Oxirane - 1-10-2014 at 14:22

Wood would probably be less harmful overall and work as a practice to see how all is going. Also cleaning the mess from PVC pyrolysis can be a real PITA. It's good to wash all the parts with toluene, it seems to dissolve all that gunk readily.

aga - 1-10-2014 at 14:26

Ok I am going to stop reading this thread now, I found some PVC pipe off cuts in a shed

. The temptation to have a go is increasing, so for the sake of safety I will follow no more

. good luck though, its a really neat way to do something with a waste product

Do it Small Scale and Lab-wise to get the maths right (as blogfast25 suggested a while back)

~1 gramme of PVC, test tube, burner, water trap followed by cold trap.
Note all the exact weights of everything, and volumes of liquid in each trap.

Hit the TT with heat until stuff stops happening (~300+ C)

Note everything you can. Temprtatures, Times, Weights etc.

Titrate the water, weigh any stuff in the cold trap.

Scientifically, Your data will be more useful than what i'm welding up.

aga - 1-10-2014 at 14:30

Wood would probably be less harmful overall and work as a practice to see how all is going. Also cleaning the mess from PVC pyrolysis can be a real PITA. It's good to wash all the parts with toluene, it seems to dissolve all that gunk readily.

Does toluene dissolve PVC as well as the black stuff ?

Late here, so will have to try that tomorrow.

Oxirane - 1-10-2014 at 14:38

I must say I've never tested it on the plastic itself, but the solid distillate residue dissolved almost immediately upon pouring in some toluene. It was very easy to clean the parts which I was afraid needing weeks of submersion as once happened in another case.

Some sources indicate that toluene would dissolve at least some PVC, and compatibility charts rank it as not compatible in all forms. VinyLoop uses probably THF or something like that to dissolve PVC from other plastics and recycle it in high % and I though about this in order to quickly utilize pvc from difficult sources like cables and shallow parts, but it would consist a major work to handle the solvent, not talking about the sheer price of it..

aga - 1-10-2014 at 15:03

>not talking about the sheer price of it.

Good Point.

I'll do Wood first.

Little_Ghost_again - 2-10-2014 at 01:13

Ok I will see if my gas mask is upto the job

. I am definitely up for the wood one

.
Since last year I have been playing with building a wood gas generator. I go look later and see if I can scale this down safely.
I will take notes etc

.

As a side note is it worth also doing this under reduced pressure? I could use a very thick walled conical flask as the reactor vessel.

[Edited on 2-10-2014 by Little_Ghost_again]

blogfast25 - 2-10-2014 at 04:12

I must say I've never tested it on the plastic itself, but the solid distillate residue dissolved almost immediately upon pouring in some toluene. It was very easy to clean the parts which I was afraid needing weeks of submersion as once happened in another case.

I doubt if toluene would work as a solvent for PVC: too chlorinated, too high MW.

@Aga and Oxirane: are you using unplasticised PVC? Plasticised PVC contains dioctyl phthalate (well, di-(2-ethylhexyl)-phthalate, off the top of my head), which would probably come off too at high T. Not to be confused with benzene/other aromatics!

blogfast25 - 2-10-2014 at 04:14

As a side note is it worth also doing this under reduced pressure? I could use a very thick walled conical flask as the reactor vessel.

Personally I don't think it's worth the hassle.

aga - 2-10-2014 at 06:18

@Aga and Oxirane: are you using unplasticised PVC?

Not the foggiest idea.

Mine was a bit of straight drainpipe connector, saying 'PVC-B' on it.

blogfast25 - 2-10-2014 at 08:34

Mine was a bit of straight drainpipe connector, saying 'PVC-B' on it.

Ok. If it's kind of hard and not very flexible it's uPVC, like your piece. Also uPVC: most PVC plumbing, PVC window frames, PVC cladding, fascias and other exterior bits on a house, most PVC flacons and containers.

Plasticised PVC: garden hose, vinyl gloves, vinyl flooring, vinyl shower curtains, low quality plastic seals and other generally soft and flexible PVC items.

aga - 2-10-2014 at 11:32

so the 'u' in uPVC means 'unplasticised' ?

Edit

Sorry. Just googled it and Yes it does.

[Edited on 2-10-2014 by aga]

Little_Ghost_again - 4-10-2014 at 02:50

The wood one is interesting, I have vague memories of reading about different woods and what they yield, also the splitting of cellulose etc, with so many different trees here I might give this a shot. I assume we are after saw dust? Or maybe fine shredded fiber? I was thinking willow put through a high power shredder gives a kind of fluffy fiber.
First the hose pipe and boiling tube (save me cutting stuff up too small)

xfusion44 - 9-10-2014 at 13:24

Few months ago, I did this experiment (pyrolisis of plastic) and I ended up with product seen on picture below. It has really strong smell of I don't know, maybe gasoline/diesel or something like that. It burns similar to diesel - releasing lots of soot, but the color is rather yellowish, than black and it's rather oily liquid. I don't know what stuff is this, but probably all kinds of different toxic chemicals... I made it using a lot of different plastics, but I've also tried only with PS plastic and the appearance of product was pretty much the same...

[Edited on 9-10-2014 by xfusion44]

[Edited on 9-10-2014 by xfusion44]

blogfast25 - 10-10-2014 at 12:06

@xfusion44:

Some more detail would be welcome.

xfusion44 - 10-10-2014 at 22:48

@blogfast25

Well, what do you have in mind?

If you mean how I've done pyrolysis itself, I've used empty acetone can (I threw pieces of plastic inside) and then attached copper pipe to it (I sealed the gap with 100% PTFE tape). Then I've heated the can with butane burner and directed gases to the beaker with cold water. When plastic started to boil, it started to decompose and the gases produced were cooled by water and formed that liquid, which floated to the top of the water. Then I just separated the product from water by pipette and that's it.

PS: if doing that, you may need to stop the process from time to time and let the water cool, to prevent evaporation of the product and insufficient cooling of the gases. Anyway this does not necessary happen if you use larger quantity of water (better heat dissipation ability).

[Edited on 11-10-2014 by xfusion44]

Little_Ghost_again - 11-10-2014 at 06:02

What is the pH of that solution?
Do you have a fractionating column?
Have you tried to distill it using tight temperature bands for the fractions?

Failing that would it be possible to do a TLC on it?

If you leave 5ml out how much evaporates in say one hour (weight wise), does the colour change if it evaporates?

Approx how much plastic is that?

Sorry for all the questions but I got a feeling about this

blogfast25 - 11-10-2014 at 06:28

LGa:

I'm rather surprised he got a clearish liquid pyrolysis product at all, instead of black goo. Starting from undifferentiated 'plastic' (there are literally hundreds of commercially used polymers today) leads of course to a witch's brew that would require serious separating power to obtain something useful.

Oxirane - 11-10-2014 at 08:49

It is very easy to get liquid distillate in large amounts from any PE, PS, PP or these common plastics. It is actually performed in large scale. XFusion's product looks pretty familiar, and by greenish color I would say there was little residue of PVC, pure PS yields mostly deep yellow liquid.

PE and PP yield mostly medium length hydrocarbons and major impurities are BTX. With fractionation these can be used on diesel engine. There was an article on this on a german forum where guys made a reactor from oil drum and produced quite large amounts of fuel subsitute from common waste plastic. From PS one will get mostly styrene which can be fractionated to pure form as well. 5-30% will be gaseous form, and one can actually use these to fuel the heater for the reaction. There will be 10-20% of weight of residue which is very dark, heavy fuel oil-type goo and soot, which is sticky as hell and probably very highly carcinogenic.

From PVC there may be little liquid residue. It should be mostly benzene, if it is common, non-mixed PVC. PVC must not be used if liquid fractions are wanted, because large amounts of HCl formed, which may contaminate the liquid and cause major problems in use.

[Edited on 11-10-2014 by Oxirane]

Little_Ghost_again - 11-10-2014 at 08:55

LGa:

I'm rather surprised he got a clearish liquid pyrolysis product at all, instead of black goo. Starting from undifferentiated 'plastic' (there are literally hundreds of commercially used polymers today) leads of course to a witch's brew that would require serious separating power to obtain something useful.

Yes but its clear.......

Is it possible that there is a strong oxidizer in there that ate most the gunk? That fact its clear makes me think its worth a look into it.

It also looks very much like a petrol type mix. He might have thought he used many plastics but when I went a looking around here for PVC all I could find was various versions of PP and PeP.
So just maybe he actually used just one or maybe two different types. That may account for the clarity. I tried drain pipe and got awful smelly black thick residue.
I tried milk bottles and got a awful smelly yellow liquid........So bad I had to chuck it straight away.
Surely its worth a couple of test's?

blogfast25 - 11-10-2014 at 09:27

[It also looks very much like a petrol type mix.

Hmmm... what something looks like and what it is are poorly correlated: could you distinguish a bottle of diesel from a bottle of water, even from small distance? Careful of wishful thinking and confirmation bias.

blogfast25 - 11-10-2014 at 09:35

major impurities are BTX. [Edited on 11-10-2014 by Oxirane]

BTX?

Little_Ghost_again - 11-10-2014 at 09:44

[It also looks very much like a petrol type mix.

Yes very sorry I wrote that poorly, I wasnt trying to say he had made petrol. I was kind of thinking more down the lines of flammable fractions or oils. Plus his description of smell suggest something in there might burn.
I do find the whole thing interesting but cant help feeling this is a dangerous path.
Like you said its a brew of god knows what. I doubt its something safe to mess with without taking precautions.

xfusion44 - 11-10-2014 at 14:47

What is the pH of that solution?
Do you have a fractionating column?
Have you tried to distill it using tight temperature bands for the fractions?

Failing that would it be possible to do a TLC on it?

If you leave 5ml out how much evaporates in say one hour (weight wise), does the colour change if it evaporates?

Approx how much plastic is that?

Sorry for all the questions but I got a feeling about this

-The pH seems to be around 7, but I don't know if pH indicator paper is really best to use with oily liquids? Well, it seems to be good. If it wouldn't be 7, it would mean, that I have an acid or base.

-No, I don't have fractionating column, I just have the "device", which I described in my last post.

-No, I didn't try to distill it, I just wanted to see if I could get usable fuel out of it.

-Sorry I don't have equipment for TLC.

-I would need to try that with evaporation (I think that the color wouldn't change, but there are some small crystals, that formed over time, who knows, what that would be - interesting).

-I don't really know, I think I used maybe 100grams of plastic, but I didn't used it all.

-No problem, just ask anything you like

I'm not sure, but I think I've used only HDPE, LDPE and PS. Oh, I've forgot how strong that smell is - when I was checking pH of it, it made whole room smell... And I can tell: don't breathe it, it can happen fast, that you'll become nauseous and you'll get headache. I seriously doubt, that this is not very toxic product.

Oh, and I have this erlenmeyer flask kept closed with ballon over it, but the smell can come through, if you smell it from small distance and it even dissolves ballon rubber.

PS: if you want to know, how it smells, just heat PS plastic until boiling and smell the vapors (that's exactly how it smells). DON'T SMELL IT TOO MUCH!

[Edited on 11-10-2014 by xfusion44]

xfusion44 - 11-10-2014 at 14:54

It is very easy to get liquid distillate in large amounts from any PE, PS, PP or these common plastics. It is actually performed in large scale. XFusion's product looks pretty familiar, and by greenish color I would say there was little residue of PVC, pure PS yields mostly deep yellow liquid.

PE and PP yield mostly medium length hydrocarbons and major impurities are BTX. With fractionation these can be used on diesel engine. There was an article on this on a german forum where guys made a reactor from oil drum and produced quite large amounts of fuel subsitute from common waste plastic. From PS one will get mostly styrene which can be fractionated to pure form as well. 5-30% will be gaseous form, and one can actually use these to fuel the heater for the reaction. There will be 10-20% of weight of residue which is very dark, heavy fuel oil-type goo and soot, which is sticky as hell and probably very highly carcinogenic.

From PVC there may be little liquid residue. It should be mostly benzene, if it is common, non-mixed PVC. PVC must not be used if liquid fractions are wanted, because large amounts of HCl formed, which may contaminate the liquid and cause major problems in use.

[Edited on 11-10-2014 by Oxirane]

It just looks like that on the picture (in reality it isn't greenish, only yellowish). And over time some crystals formed in it, as I mentioned in post above.

Oxirane - 11-10-2014 at 15:00

The smell of styrene is very distinguishable. Your product is very much like mine when I did PS pyrolysis, it smells very strongly, it has nice chemical-laced sweet aroma and it will form some white crystals eventually. They are likely polymerization products, and the distillate can be purified by fractional distilling it.

BTX stands for Benzene, Toluene and Xylene. A term from pet industry. Sorry.

xfusion44 - 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?

Little_Ghost_again - 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

xfusion44 - 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?

Little_Ghost_again - 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.

blogfast25 - 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.

xfusion44 - 12-10-2014 at 04:28

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

xfusion44 - 12-10-2014 at 04:29

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

aga - 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 ?

blogfast25 - 27-10-2014 at 12:28

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

Have you tried condensing some of it?

aga - 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]

aga - 27-10-2014 at 13:28

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

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]

blogfast25 - 28-10-2014 at 05:27

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

plante1999 - 28-10-2014 at 06:15

Many plastic are reputed to produce benzene upon pyrolysis, but it is really dependant on the temperature.

aga - 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.

blogfast25 - 28-10-2014 at 13:07

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]

Oxirane - 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.

careysub - 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.)

aga - 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.

plante1999 - 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..

aga - 28-10-2014 at 15:10

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.

plante1999 - 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.

blogfast25 - 29-10-2014 at 05:41

]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.