Sciencemadness Discussion Board

Thy famous tubes - a scrapyard approach

Organikum - 12-3-2004 at 09:59

I n this thread I will document an approach to build a multipurpose furnace tube by the most simple means without any hard to get parts or catalysts. The tube shall be used in oxidations/dehydrogenations, like toluene to benzaldehyde/benzoic acid, ethylalcohol to acetaldehyde/acetic acid and more. It is by no means sure that it will work well also I am sure it WILL actually work more or less. The approach aims for simplicity and selectivity, say purity of product, the actual yield per pass is not important here. Unreacted substrate will be refed and if higher throughput is wanted the tube can simply be made bigger or preferable multiple tubes may be used.

Here a first picture of the rawmaterials which I plan to use.

I will post pictures of every single step of building this - this tells more than 1000+ words I believe, but one point may be disclosed in advance:
It is a "boilerless" design I will try to implement here for safety and simplicity.

here we go


axehandle - 12-3-2004 at 10:17

I'm doing basically the same thing, only difference is that my burner will only be burning sulfur.

My approach is basically the same, apart from material choices.

And dare I suggest an addition to your general purpose burner? Well, I'll do it anyway: Add an air dessicator somewhere in the air pump feed path. I'd suggest a CaCl2 column. It's not really general purpose if you feed the odd water molecule from time to time... :)

You can see some of my ideas at

Edit: I should really submit some pictures of my scrapyard-contents-built copper melting capable propane burner..... it really kicks. In lack of a picture, it's basically a Reil burner with an adjustable air feed blower. Melted a distillation borosilicate vessel by accident once....

Edit2: Whoooooaaaahhh!!! My weblog just started vomiting access lines like a maniac!

[Edited on 2004-3-12 by axehandle]

[Edited on 2004-3-12 by axehandle]

Organikum - 12-3-2004 at 10:47


I'm doing basically the same thing


axehandle - 12-3-2004 at 11:39

Yes, really. Well, not <i>exactly</i> the same, but still... it's a strange coincidence, no?

It's funny how people who think somewhat alike often take on the same thing at the same time... like trying to call another at the same time, deciding to build something, etcetera....

Tacho - 12-3-2004 at 11:53

OK, let's see... What is the blue stuff? Why do you need steel wool?
What is the orange gadget?

Humm... I understand the tube will be made of copper and you will insert the glass tube inside of it as needed, is that right?

You wouldn´t, by any chance, be in need of a thermostat, would you?

Have I ever told you about the wonders of dentist´s phosphate cement?

axehandle, I gess I found a new victim.

axehandle - 12-3-2004 at 11:56

Tacho, are you planning on shoving 30 thermostats down Organikum's throat as well? :)

To be honest, I don't feel like a victim, you have been a great help to me, especially with the molten salt thermostat. <b>Very</b> impressive and innovative work. Needless to say, I'll use it.

Edit: Btw, copper isn't inert enough. Organikum, I suggest you use osmium-plated iridium instead. Much easier.

[Edited on 2004-3-12 by axehandle]

Organikum - 12-3-2004 at 12:53


if you two look into some of my older posts you may find that tubes are not really new to me.......

It's funny how people who think somewhat alike often take on the same thing at the same time... like trying to call another at the same time, deciding to build something, etcetera....

Eh, thus honors me, but I just need some benzaldehyde, thats all....

[Edited on 12-3-2004 by Organikum]

Organikum - 12-3-2004 at 13:10

No, there is no glasstube to be inserted into the coppertube, why should this be done?

The orange thingie is a hairdryer, 350W, somehow oldfashioned.....
Also there is a dimmer for comtrolling the temperature, some coppersulfate, a toaster (400W) with nice ceramictubes for heating which make isolation between the coppertube and the heatingpart neglectable and some steelwool which is bound to serve as preheating and condensation enhancer - it will be pushed in the relevant parts of the tube....



[Edited on 12-3-2004 by Organikum]

unionised - 12-3-2004 at 16:38

Hot steel wool is not known for it's inert nature.

Organikum - 13-3-2004 at 01:57

unionised wrote:

Hot steel wool is not known for it's inert nature.
Btw. you didnt bother reading my first post where I descriped for what purpose I am building this tube furnace, did you?

Tacho - 13-3-2004 at 02:23

Thanks axehandle. I just tested it and it is still OK.


I attached a drawing of two possibilities. Maybe I got it all wrong. Using the search engine here is a pain, because everytime you go back, the page has expired and you have to do it again. Searching all your posts is not an option.

Take a look and tell me which, if any, are you planning to built.

Tubeoptions.jpg - 12kB

unionised - 13-3-2004 at 07:58

So far as I can tell from this thread (and you don't seem to have included a reference to any others) your first post starts with the words "In this thread" and ends with "here we go.
It doesn't mention steel wool in between those phrases.
It does talk about oxidation and I presume that you will be using air as the oxidant (again, it isn't specified).
Steel wool is not known for tolerating "hot air".
Please let me know what it is that I haven't read.

Organikum - 13-3-2004 at 10:55

The (stainless btw.) steelwool is for preworming toluene or ethylalcohol at about 100°C to 150°C, I doubt this will hurt in any way. This is a tube for ORGANIC oxidations, the steelwool is not in the reactor itself (and if it will with coated by copper/copperoxide).

But I made an quick experiment and heated the wool for 30minutes with my hot-air pistol which is rated at 500°C. Nothing happened. So I guess that steelwool can stand hot air very well.

My experience

ballzofsteel - 13-3-2004 at 11:57


Wow,that resembles the makings of a furnace i once built.

When opperating my furnace for the uses mentioned previous,I toyed with various catalyst composition and substrates,-
My first attempt being that of simply attatching a copper tube filled with copper scrub pads to the top af a flask and heating the tube until red hot with a stove element, then passing vapour through this,resulting in fruity aromas in the vapour trap and that was about all.

I found that in low-tech applications a nice catalyst was produced by simply steaming(in a kitchen steamer) some copper scrub pads over vinegar,and then reducing the
acetate coating on the pads, in a fashion not so dissimular to the method you suggested in the acetaldehyde thread,e.g
heat and hold,heat an hold to +-450c.

The beauty of a furnace of this design,is that one can controll the heat,making for
better catalyst production and selectivity.

A better catalyst was produced by steeping activated filter carbon into a hot Cu acetate sollution and then heating until dry,but not at a high enough temp or over a long enough duration to reduce the acetate to oxides.
I would then fill my tube with this carbon support and then top the tube up with more acetate sollution.
Id slowly crank the heat tube to its highest temp,along the way holding the temp every 100deg or so for 3-4 hours at a time.
Let it cool,Invert the tube and then repeat a time or two more.
I dont remember the precise details,
but I got the idea from a patent I found which decribed the entire process,including furnace design/dimensions etc.
Unfortunately,I never atempted to activate the catalyst by passing H2 over the catalyst.

I also tried using bought copper oxides without any of the activation steps,without nearly as much success as the home-preped catalyst.
I think much to do with that was the inhibited flow rate of the vapour stream,
due to being careless and simply coating,or dusting some ground scoria with the oxide and using that as is.
Basically clogged the tube.

I am interested to see how you work such a device without a boiler.
I assume you will include an air-port,pre tube?
I found this seemed to help the process quite substantially if a LIGHT stream of air was introduced.

Sorry Org Ill stop shitting in ya thread now.
Carry on.
Look forward to your picture essay.

Thats a funky toaster btw.

[Edited on 13-3-2004 by ballzofsteel]

[Edited on 13-3-2004 by ballzofsteel]

gritty_cryst - 13-3-2004 at 12:19

Very interesting project...
Eagerly awaiting reports of progress.

Organikum - 13-3-2004 at 13:54

Thanks Ballz, was helpful what you wrote. The copper-acetate patent is known to me, it is US2002/0143213A1, if I am right....
As told, I am sfter the most simple way now...not sure how it will work though.

The tube will work like a carburator, the fan blows air in, a small nozzle/tube inserts toluene/EtOH and some heated steelwool makes sure all is well mixed and in gasphase when it hits the hot catalyst.

Pictures will be made furtheron to show the howto. First run is tomorrow night so everything works well. :D

Here we go.


axehandle - 13-3-2004 at 16:16


Eh, thus honors me, but I just need some benzaldehyde, thats all....

No, it honours me.

Organikum - 14-3-2004 at 07:39

This resembles my ideas best:

Courtesy Polverone.

Somebody traveled through time, stole my ideas and wrote an article in the past. Its always the same....

unionised - 14-3-2004 at 16:41

Just on the off chance that someone is interested I made a tube furnace too.
I got a foot of half inch brass tube, filled it with granular copper oxide, wrapped it with filter paper (Whatman's GF/A) and then wound on nichrome wire (about 4.2 ohm/ metre). I put a thermocouple against this and then more layers of the same paper. I then wrapped it with glass cloth and finally put it in a pyrex tube.
I connected the nicrome to a 50 V transformer (100W IIRC) that was controlled with a phase angle controller.
I turned up the voltage until the meter connected to the thermocouple said 300C.
I had hoped to use it to oxidise ammonia to nitrogen. Unfortunately (from my point of view) it gave a mixture of NO and NO2.

axehandle - 15-3-2004 at 02:47


I had hoped to use it to oxidise ammonia to nitrogen. Unfortunately (from my point of view) it gave a mixture of NO and NO2.

Which could be very useful for using the lead chamber process for H2SO4 production, without using xNO3!

Edit: Or for making 68% nitric acid...

[Edited on 2004-3-15 by axehandle]

Organikum - 15-3-2004 at 07:13

unionised, you have to heat the tube to a red glow for the HN3 to nitrogen oxidation, this is best done by an propane burner.

There must be a thread somewhere here on nitrogen production (as inert gas) under my name.

Hey! I think its great that more members are going to play with the hot tubes! They are nifty devices and sooo useful in many ways - collecting and sharing our experiences will bring us a big step foreward in whatever direction we want to go!

[Edited on 15-3-2004 by Organikum]


Note to other members: This might be one of Orgies evil plans to grab world domination. Be careful and use your tinfoil hat!

[Edited on 15-3-2004 by vulture]

axehandle - 15-3-2004 at 14:12

And for fuck's sake, don't BUY a propane burner. You can build one from scrap plumbing and some brass rod for next to nothing. If anyone's interested, I'll document my monster burner on my homepage. That was an RFC.

Organikum - 15-3-2004 at 14:29


If anyone's interested, I'll document my monster burner


Dont think I havent seen it Vulture.......

axehandle - 15-3-2004 at 14:34

Very well. I'll begin now. There will shortly be a section on my homepage titled "Monster Propane Burner". :)


axehandle - 15-3-2004 at 15:18

Edit: If anyone wants to see the flame of burning hell, I could, with some longer network cable to the Axis camera server, take pictures. Suffice to say, it's <b>VERY</b> hot...

Edit2: And it <b>gobbles</b> propane too fast for my economy. I'll have to buy a 0.6mm drill....

[Edited on 2004-3-15 by axehandle]

[Edited on 2004-3-15 by axehandle]

unionised - 15-3-2004 at 15:59

I didn't want NOx; I still got it and I didn't have the thing red hot. I wanted nitrogen for an N2 laser. The reaction of ammonia and air seemed a really neat solution. Air's mainly N2 all I had to do was strip out the O2 (I didn't care about the other stuff, Ar etc.). Using ammonia as a fuel gave more nitrogen as a by-product. Just what I wanted. the only problem was it didn't work.
It might have worked better if I had a greater ammonia concentration to work from.
I got bored of this game and used sulphamic acid and sodium nitrite.

axehandle - 15-3-2004 at 16:22

And noone is impressed with my burner... sigh. Guess I'll have to take a few shots of it burning....

[Edited on 2004-3-16 by axehandle]

Organikum - 15-3-2004 at 17:48

N2 - nitrogen from air


Next time please search for your own.

Organikum - 15-3-2004 at 17:57

Nice work!

THIS resembles utmost my tube furnace concept. More or less of course... :D

axehandle - 16-3-2004 at 14:18

Thanks. Did you need an air dessicator in series with the intake? I built one:

ballzofsteel - 17-3-2004 at 06:58

I dig the steel wool idea for sure.

I know the patent you have noted.

Here is another simular, but more straight forward.

patent 4,220,803
Cu acetate for acetaldehyde

Organikum - 17-3-2004 at 09:52

Thanks Ballz, but the patent youn name doesnt use the acetate as catalyst but it uses the acetate to prepare the catalyst which is the oxide.

Doesnt matter though.

Organikum - 17-3-2004 at 11:52

Thats the substrate injector

The tube goes straight to the can siphonning the substrate out and delivering it to the tube. The hot air from the hairdryer will hopefully take the substrate with it forward to new adventures......

The inlet is a slaughtered bicycle tire valve, screwed into a hole of the coppertube with some teflon tape. In the copppertube there is some steelwool for distributing the substrate and for the higher surface area facilating evaporation.

At least I would like it to work this way...

[Edited on 17-3-2004 by Organikum]


trilobite - 17-3-2004 at 15:25

Hairdryers' often have an overheating protection which makes them turn off even when they aren't used to pump air through a catalyst tube. I'd pump air with a suitable pump and wind nichrome wire, with proper insulation of course, around the pipe for heating.

Interesting thread by the way.:)


ballzofsteel - 17-3-2004 at 16:57

Yeah,thats what I said?
Reduce it to oxide.
I believe the acetate is reduced to oxide when used as a semicatalyst anyhows right.Especially @300deg.

Do you plan on any amount of pressure
within thy tube?

I dont quite understand how the siphon feed effect is meant to work.

Are you being literal? Or is it supposed to act on some type of venturi system?
E.g the vaccume caused by the fan/expanding vapour?
In either case,I think a finer diameter copper capillary tube would work much better for the feed inlet
Less surface,less vaccuum needed greater control,durability.
Plus I hate pvc tube.
You couldnt have to great a reducer in between the tube outlet and the condensor for fear of "backpressure".

Say,for once the siphon begins,how will you stop it from flooding the tube?
If you meant siphon that is.

With a couple more bucks spent on copper,and a tap/dye you can easily build a fully automated/safe/recycling system.
Ill post some ideas/design this evening.
Not hard,Just more pipes.

axehandle - 17-3-2004 at 17:37

I could punctuate better than that in grammar school.

Organikum - 18-3-2004 at 04:35

Punctuation isnt important. Proper cApitAliZaTiOn is what you need to survive :D

Two pictures from a first catalyst preparation test. Copper precipitated on steelwool from hot CuCl2 solution - works like a charm, one can imagine the fractal structures which build up and which will make the big surface area desired for use in the tube furnace.

Thats the partially covered steelwool.

Thats a nearer view to make the idea better imaginable.

The steelwool was washed several times with perchlorethylene to remove oily and fatty residues - thats a MUST DO any defatter should work - then with cupious amounts of water and in the end with distilled water.

Looks good.

I made the reducing piece with gypsum as you told axehandle. If the tube wont work I will blame it on you, ok?

[Edited on 18-3-2004 by Organikum]

Organikum - 18-3-2004 at 07:37

I know of the problems hairdryers have because of the overheating. For this reason I got me an old, low-power (500W max.) dryer. It runs at the moment with the reducing part applied and it seems to work well.

New 1000W+ hairdryers are not very useful here, I agree, to much hassle, better getting an old one than removing the heatsensor and having a "hairdryer meltdown".
Been there, done that....

Organikum - 19-3-2004 at 12:07

trilobite right, Organikum wrong, hairdryer quits as soon it has to work against some resistance in the flowpath.

Problem: Airflow and preheating of substrate.
Solution II: 12V computer CPU fan as blower, the hairdryer as separate preheater directed to the tube.

Pictures as soon as the gypsum for the adapter has dried out a lil´ bit - the actual reaction tube will be depicted also then.

madscientist - 13-4-2004 at 22:31

The tube shall be used in oxidations/dehydrogenations, like toluene to benzaldehyde/benzoic acid,

How is that done?