| Pages:
1
..
3
4
5
6 |
Oxirane
Hazard to Self
Posts: 92
Registered: 19-9-2014
Member Is Offline
Mood: No Mood
|
|
Your results seem very similar to mine. The HCl water trap got contaminated with yellow-browish tint, which probably could be purified to some extent
by filtering it through ceramic or silica sand filter and maybe even activated charcoal, if it doesn't absorb HCl on it's own. Very good cooling of
pyrolysis gases seems to be important, but because I noted that there condensed thick gunk which could potentially block some of the lines, the fumes
should be led directly to a submerged condensing flask and then exhausted through reflux condenser into a tube and out to the water trap for HCl
collection.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
8 g of liquid pyrolysis products out of 237 g PVC and after 85 minutes of runtime seems a little... underwhelming, considering your effort. You'll
need a longer run or continue this one to see if more 'goo' can be squeezed out...
Like oxirane suggested, active charcoal may remove the worst of the colour.
Hard to distil such small quantities too. For that I suggest a temporary mini-still cobbled together from a boiling tube, some glass tubing and a
cooled receiver test tube, for a crude single plate distillation. De-water the 'goo' first, though. And hope extending the run will give more 'goo'...
I'm a bit unclear about how you capture the 'goo' though. It is supposed to go into the white PE or PP large bottle but I see only 1 inlet/outlet (the
ball valve)? Why not collect the 'goo' directly in the first of the two conical flasks (the vac flask, tssk, tssk!)?
[Edited on 29-10-2014 by blogfast25]
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
That'd be the anti-suck back too full then, to be any use as anti-suck-back innit.
Idea was to let any Liquid phase stuff leaving the condenser drop into the bottle, while Gas phase stuff carries on into the anti-suck-back, and then
into the water.
Personally i see the experiment as a dismal failure, but then, that's what experimenting is all about - Discovery, Trial and error, hopefully
Learning.
From Observation, Stuff Happens at 300 C+
For this Rig, that means Log On more often.
The drops in temperature correlated nicely with Lack of action.
So, next run will be chopped up sun loungers or chairs, whichever gets Discovered (i.e. discarded) first.
Should Benzene burn easily ?
Some of the leaking fluid was absorbed onto some paper, and it it didn't burn at all.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
Quote: Originally posted by Oxirane  | | Your results seem very similar to mine. The HCl water trap got contaminated with yellow-browish tint, which probably could be purified to some extent
by filtering it through ceramic or silica sand filter and maybe even activated charcoal, if it doesn't absorb HCl on it's own. Very good cooling of
pyrolysis gases seems to be important, but because I noted that there condensed thick gunk which could potentially block some of the lines, the fumes
should be led directly to a submerged condensing flask and then exhausted through reflux condenser into a tube and out to the water trap for HCl
collection. |
My HCl collector is mostly Clear, with what looks like black Oily crap floating on top.
Likely SOS left over from the Wood pyrolysis.
Even though the Gasses do not even get all of the copper pipe Warm, never mind Hot *before* they enter the condenser, all products left the condenser
Cool, i.e. < 45 C.
Some gasses were seen leaving the second pot.
|
|
|
plante1999
International Hazard
Posts: 1936
Registered: 27-12-2010
Member Is Offline
Mood: Mad as a hatter
|
|
I heard HDPE is one of the best substrate for BTX production.
Preferable temp appear to be 600 C
|
|
|
deltaH
Dangerous source of unreferenced speculation
Posts: 1663
Registered: 30-9-2013
Location: South Africa
Member Is Offline
Mood: Heavily protonated
|
|
Loved your rig Aga!
A suggestion if I may... I don't know if you're after the HCl as a co-product, but it sounds to me more of a pain than its worth (especially to your
apparatus). What about mixing your PVC with lime and then pyrolysing? This way the lime reacts with the HCl formed in situ to generate water
and solid calcium chloride and plus the lime would also act as a heterogeneous base catalyst to the pyrolysing melt that may (or may not) help....
making tar/coal being the worst case scenario 
If it works your condensate would consist of a two phases, water and aromatics. I presume if any aromatic oxygenates (e.g. phenols, cresols, etc)
form, they would concentrate in your aqueous phase.
I cannot say for sure about the potential dangers of doing so, though... For example, the reaction between the lime and the PVC would probably be
exothermic once it gets going (potentially a good thing if not too exothermic), but this could lead to a thermal runaway. A test tube sized test prior
to employing your rig may be a prudent precaution. Also be aware that poisonous CO could also be produced. Heck, now that I think about it, it might
just make lots of syngas and 'carbon', aka black crap... 
[Edited on 30-10-2014 by deltaH]
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
aga:
Yes, benzene is quite flammable. Which is why you should be very careful with any joints on the pyrolyser being fully airtight. You've got open flames
there!
I still don't really understand your set up: seems to me there's only one inlet into the intended organics collector (the large plastic bottle) and no
outlet.
I think 300 C is still way too low. Try a charcoal fire or a combination of wood and charcoal, with lots and lots of air. The more air, the
more combustion, the higher the temperature. Think BBQ.
At 300 C only a small part will depolymerise or it will take a century to get to say 80 % depolymerisation.
[Edited on 30-10-2014 by blogfast25]
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
Ah. So if it *had* worked as planned, it could have exploded.
Excellent.
Maybe the photos don's show the setup too well.
Out of the condenser is a T-piece, the bottom part of the T is where the plastic bottle is.
The orange pipe takes the Gas into the buchner on the Left, via the spout.
A bung in the top has a glass pipe, connecting to the clear plastic pipe leading to the Buchner on the right, which also has a glass pipe leading from
the bung down to just below the level of the water, which is Only in the right hand flask.
The Outlet is the spout on the right hand buchner.
In the event of suckback, the left hand flask would catch some liquid until the level of water in the right hand one fell by about 5mm, after which
air could flow freely through both flasks.
|
|
|
Oxirane
Hazard to Self
Posts: 92
Registered: 19-9-2014
Member Is Offline
Mood: No Mood
|
|
Minor leaks are not hazardous since the apparatus is filled with HCl and vapors which dispalce oxygen, so only the leaks would ignite after exiting
the vessel.
You should apply heat liberally, plastic pyrolysis occurs mostly at temperatures over 300, usually between 350 to 600 degrees. Even though PVC starts
to decompose at 200-250, the decomposition products do not differ unless the temperature gets so high the molecules start to decompose, but I find no
risk for anyone here getting such high temperatures unless electric heaters or forced oxygen flames are used. I applied 6kw propane heater under a
200x300mm cylindrical reactor which had 100mm layer of rockwool insulation all around it except bottom and the HCl generation rate became quite high
at the end of it. With your setup I see a chance for very slow decomposition, so bring the pot closer to the flame.
But afterall, PVC is not a good source for benzene, but HCl. It will generate almost 50% by weight of hydrogen chloride, whileas only 1-10% will be
recovered as benzene and rest will be carbon monoxide, dioxide and hydrocarbons of different sizes and lengths. Polyethenes with or without zeolite
catalysts are better for obtaining BTX as said before. PVC should only be regarded as a viable source for HCl.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
PVC is certainly good for HCl, and Plenty of it.
My observation was that around 270+ C things start happening.
Perhaps Benzene was being a little too ambitious.
Here's a photo of the poor old PVC post-pyrolysis.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Aga:
Explosion/fire would only occur with direct leakage from the pyrolysator and proximity of open flame. DO make sure any seals on that part are secure.
I see what you mean now and it is what I thought it was: the T-junction acts as inlet/outlet on the plastic collector. That's far from ideal: think of
what happens when you empty a full bottle into a glass or container: the liquid is trying to exit at same time air needs to enter the bottle. Here's
it's the reverse: condensate tries to enter the bottle while air must try to get out at the same time. It won't work very well when your condensate
flow is larger.
"PVC is certainly good for HCl, and Plenty of it." Did you titrate the HCl? It could be a good way to follow progress of the pyrolysis.
Oxirane:
"[...] but I find no risk for anyone here getting such high temperatures unless electric heaters or forced oxygen flames are used."
Hmmm... even my paint can charcoal fired furnace melts copper (at a push). With good geometry and plenty air, charcoal fire will melt steel!
[Edited on 30-10-2014 by blogfast25]
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
660 C is relatively easy with charcoal and a hairdryer (melting Al)
Not so sure i want a partially sealed 10 gallon tank at 660 C next to me in a field though.
No, i have not yet titrated the HCl.
As before, with the 1L can, there is a stack of HCl left floating about in the reactor, which escapes and gasses you when you open the door.
I closed the door before the cloud was big enough to cause serious Weather Events and squirted some water into the other end to absorb it.
Makes the skin on your arm sting a bit when you stick it into a vat full of HCl gas.
(grabbing that lump of carbon for the photo)
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by aga | 660 C is relatively easy with charcoal and a hairdryer (melting Al)
Not so sure i want a partially sealed 10 gallon tank at 660 C next to me in a field though.
|
A smaller reactor would be safer. Something like a defunct car fire extinguisher, for instance.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
| Quote: Originally posted by Oxirane |
You should apply heat liberally, plastic pyrolysis occurs mostly at temperatures over 300, usually between 350 to 600 degrees. |
OK. So lots and lots of heat. Thanks !
Think i can do that.
The leaks worry me, in that Stuff goes where it should not, so they will be fixed for the next run.
In deference to the flammability of any 'products' that may occur, i'll make the tank exit pipe longer, and maybe live to tell the tale.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by aga |
In deference to the flammability of any 'products' that may occur, i'll make the tank exit pipe longer, and maybe live to tell the tale.
|
That's not really the issue, IMHO, because the cooled 'products' are already much less flammable. The real danger is where the reactor exhaust connect
to the reactor: gasses/vapours are still very hot at that point, there's plenty air (for leaked product vapours) and nearby open flame and possibly
cinders flying off the wood.
What kind of seal are you using to seal that connection? I would suggest to have a piece of steel pipe welded properly to the hole in the reactor. You
can then further down the line connect the steel to the copper pipe that goes into the condenser.
Are there any other vulnerable points in the reactor, like where you load the PVC into it, maybe?
Another issue remains the connection between the tube and the product collector. Looking at one of the photos on the previous page, I can see (shock,
horror!) than the thread from the T-piece doesn't even match the thread in the defunct milk bottle (or whatever it was in a previous life)! That's a
recipe for losing HCl.
I'm a bit loathe to say [considering your effort] that this project would have much benefited from a lab bench apparatus comprised of no more
than some well connected boiler tubes, an ice bath and a HCl scrubber, for higher temperatures and much more quantitative work.  Weighing everything (walk in Lavoisier's footsteps!), determining HCl obtained,
accurate temperature control and decent mass balances could throw so much light on this most interesting problem that your more dangerous ad hoc
apparatus can not.
[Edited on 1-11-2014 by blogfast25]
|
|
|
Waffles SS
Fighter
Posts: 998
Registered: 7-12-2009
Member Is Offline
|
|
Why pyrolysis of PVC when you can try another interesting pyrolysis?
Pyrolysis of used tires
dl-lemonene is major product and also below compounds as minor products:
2,7,7-trimethylbicycloheptane
1,4-dimethyl-1,3-cyclohexadiene
1-methyl-4-ethylbenzene
1-methylpropylbenzene
1-methyl-3-isopropylbenzene (m-cymene)
2-methyl-1-propenylbenzene
2 or 3-tert-butylthiophene
Diethylthiophene
4-methyl-1-isopropylcyclohexene
Indane
4-methylene-1-isopropylcyclohexene
Butylbenzene
Butenylbenzene
1-methyl-5-isopropenylcyclohexene
2-ethenyl-1,4-dimethylbenzene
Diethylbenzene
Dimethylethylbenzene
Trimethylbenzene
Ethyl-3,5-dimethylbenzene
| Quote: |
Various samples of used car and truck tires were pyrolyzed in a batch mode under vacuum
and in a continuous feed reactor. The pyrolysis temperature varied in the range of
440–570°C. dl-limonene is a major product formed during the thermal decomposition of
rubber under reduced pressure conditions. The pyrolysis oils were distilled to obtain a
dl-limonene-rich fraction. The difficulty of obtaining a pure dl-limonene fraction is discussed.
A high pyrolysis temperature decreases the dl-limonene yield due to the cracking of the
pyrolysis oil. Several secondary organic compounds produced by cracking were identified by
gas chromatography/mass spectrometry (GC/MS) analysis. These compounds had a boiling
point similar to dl-limonene. The dl-limonene yield decreases with an increase of the
pyrolysis reactor pressure. The mechanism of the thermal degradation of tires leading to the
formation of dl-limonene is discussed. A dl-limonene-rich fraction was obtained following a
series of distillation. Sulfur-containing compounds in the dl-limonene-rich fractions were
analyzed by GC using a sulfur specific detector. Several thiophene-derivatives were identified.
Quantitative analysis of the sulfur compounds in the dl-limonene rich fractions was made.
An olfactometry test was performed on a standard thiophene sample in d- and dl-limonene
solutions to establish an approximate threshold value to detect the thiophene odor.
Production of dl-limonene by vacuum pyrolysis of used tiresPakdel, HJournal of Analytical and Applied
Pyrolysis2001, 57: 91–107.doi:10.1016/S0165-2370(00)00136-4
|
[Edited on 1-11-2014 by Waffles SS]
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
All eyes are on the prize: benzene. Increasingly hard to get for hobbyists.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
| Quote: Originally posted by blogfast25 | | I'm a bit loathe to say [considering your effort] that this project would have much benefited from a lab bench apparatus comprised of no more
than some well connected boiler tubes, an ice bath and a HCl scrubber, for higher temperatures and much more quantitative work. Weighing everything (walk in Lavoisier's footsteps!), determining HCl obtained,
accurate temperature control and decent mass balances could throw so much light on this most interesting problem that your more dangerous ad hoc
apparatus can not. |
I agree totally.
The 'experiment' was useless in any Scientific sense.
Seeing as i'd not know Benzene if i met it, all rather pointless too.
Welding up the rig and firing up a 10 gallon pot was fun though.
I think i have a fire extinguisher, and will take you up on your previous suggestion.
[Edited on 1-11-2014 by aga]
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
No, not useless, just flawed.
|
|
|
Oxirane
Hazard to Self
Posts: 92
Registered: 19-9-2014
Member Is Offline
Mood: No Mood
|
|
Easiest way for benzene is to get benzoic acid or sodium benzoate and pyrolyse it with sodium hydroxide. If you go hardcore, you can catalytically
oxidize toluene to benzoic acid under pressure and heat. There was a patent concerning this. Otherwise, I would still head for polyethenes if I wanted
benzene. Who seeks for it, should search internet with "plastic pyrolysis benzene".
And Mr. SS, you will certainly get hundreds of compounds out of plastics and tires, but try you to separate those into useful fractions! If you've got
a chemical plant with tens of feets high vacuum fractionating columns side by side and tons of tires to pyrolyse in a continuous process, go for it.
Did you know that you can get phenol, aniline an ammonia in tons from common coal - if you happen to have tens of thousands of tons that for turning
into coke? But for average amateur chemist with his glassware and utilized fire extinguisher reactors, only residues with few useful fractions are
reliably separated. Yes, you can make HCl from PVC, yes you can make styrene from polystyrene, but no, you probably can not separate Indane from car
tyre residue oil.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
Hmm.
Both of my fire extinguishers have Aluminium casings.
Lidl is getting unreliable these days.
A small propane tank might be better.
Car boot time.
Maybe a Butane bottle. They're steel.
[Edited on 1-11-2014 by aga]
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
300 C isn't even half way there.
"The maximum BTX aromatics yield was obtained at 719 °C"
http://pubs.acs.org/doi/abs/10.1021/ef901127v?journalCode=en...
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Oxirane | | Easiest way for benzene is to get benzoic acid or sodium benzoate and pyrolyse it with sodium hydroxide. |
http://www.sciencemadness.org/talk/viewthread.php?tid=325
(very long thread)
| Quote: Originally posted by aga | A small propane tank might be better.
Car boot time.
Maybe a Butane bottle. They're steel.
[Edited on 1-11-2014 by aga] |
Defunct CO<sub>2</sub> Sodastream bottle? Quite small.
From the abstract:
"The maximum BTX aromatics yield was obtained at 719 °C, with a value of 18 wt % of the organic product."
That caught my eye: 18 % is not a lot, the rest being 'char', I suppose. Interesting also how they suppressed chlorine by addition of oyster shells
(limestone, basically) to the feed.
And then there's this:
"Besides the pyrolysis oil, a combustible gas was also obtained. The main components of the gas were CH4, C2H4, C3H6, C4H6, and C4H10."
That is something that really should be checked too: add a gazometer after the HCl scrubber to capture non-water soluble gases. If only for safety.
Part of it will be air of course.
[Edited on 2-11-2014 by blogfast25]
|
|
|
plante1999
International Hazard
Posts: 1936
Registered: 27-12-2010
Member Is Offline
Mood: Mad as a hatter
|
|
Burn the off gases under the tank to help sustain the reaction. Use polyethylene instead of PVC.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
I got ample supplies of sun-loungers and chairs made of PVC, so needs to be PVC for me.
Eating all these oysters to get raw material is making me Fat, and fishy.
I'd just use some CaO, but i have no idea how to make it into oyster shells.
[Edited on 2-11-2014 by aga]
|
|
|
| Pages:
1
..
3
4
5
6 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
