Steam
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Chemical Resistance (Chemical Engineer Needed)
Perhaps a experienced chemical engineer can help me with this one...
I am producing dimethylamine salt for use in this reaction http://www.sciencemadness.org/talk/viewthread.php?tid=11634 (by the way, it is really cool how it changes colors). I am currently doing a large
project on this stuff for school and despite my good fumehood I am sick of the smell of rotting flesh from the amine lingering in my lab. I need a way
to produce dimethyamine without tying up all my glassware and without it being IN my lab. I would like to make an standalone device which will:
produce the salt on a decently large scale (50-100 grams of salt at a time I am thinking?), use little to no glass, be operable outside, and be rugged
enough that it can last multiple uses without to much maintenance. The method I am using calls for use of concentrated HCl, multiple filtrations, and
requires me to boil down the mixture to concentrate it. Basically I am using Vogels method.
I have been doing some ebay-ing and I found some stainless steel industrial reaction vessels and such and I have been wondering If I can use metals
like stainless steel for fabrication of a "miniature industrial chemical plant"? I have a good relationship with the shop teacher at my school and he
lets me use the machine shop every so often. Also I have a MIG welder at home and I know how to use it. I have some rough sketches of the layout of
the plant and I will scan them in the morning.
I guess what I am asking is: do any of you know if stainless steel will resist Concentrated HCl fumes, and have you had any experience doing chemistry
on this slightly larger scale.
Just so you know, I know that I could just make a few LARGER batches rather than multiple smaller ones. I would rather make
something which I can create dimethylamine in smaller amounts on demand rather than in a large quantity which will undoubtedly be laying around in my
shed in storage.
[Edited on 20-4-2014 by Steam]
[Edited on 20-4-2014 by Steam]
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
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plante1999
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Plastic are your best bet. Steels won't stand HCl.
Glass, plastic, tantalum, platinum, etc would work well, copper could work if oxygen is excluded. Lead could be an idea too.
I never asked for this.
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mnick12
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Not a chemical engineer, but as plante said most regular grades of stainless won't work.
Your regular stainless like 306 and 316 or any of the 300 series are susceptible to stress corrosion cracking in the presence of elevated levels of
chloride. If your are set on stainless, alloys with high nickel content are more resistant but also a lot more expensive. Although probably less
expensive than tantalum or platinum. The problem with chloride is that it wreaks havoc on most metals, and at a low pH it is even more pronounced.
Some of the nitrogen steels have improved chloride resistance, but stainless in general is going to get wrecked by hot HCl.
What about dedicating some glassware exclusively to this reaction? Glass seems like the ideal material here.
Edit:
Just thought of something else.
How are you making your dimethylamine? If you are making it from the hydrolysis of DMF, you could dissolve it in some non-polar solvent like ether.
Gassing the resulting solution with HCl should ppt your ammonium salt with very little water, and remove the need for boiling the solution.
[Edited on 20-4-2014 by mnick12]
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macckone
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Hasteloy B is resistant to HCl and most other chemicals.
Enameled metal is often used in industrial plants.
Enamel is essentially a thin layer of glass.
Silver plating or lead lining will provide some degree
of resistance but silver is expensive while lead is cheap.
Neither is resistant to formic acid which is formed
during the reaction.
5 gal glass water carboys can be used as
makeshift reaction flasks but extreme caution
should be used in heating them. ie. always use
an oil or sand bath.
A section of glass tubing (fluorescent light bulb)
could be used as a reflux tube.
However you would need some method of joining the
two in a removable manner. A PTFE coupling of some
kind would be ideal. However CPVC is moderately good
at handling formic acid and HCl at elevated temperatures.
Note this is CPVC not regular PVC. Dimethylamine may
attack CPVC but I don't have data one way or the other.
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Steam
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Will the steel alloys resist cont. HCl at room temperatures? ie for filtering coloumb?
Also is there a way to enamel metal at home without the use of a kiln? Maybe some spray on ptfe coating I could apply?
Definitely looking into the hasteloy B!
[Edited on 20-4-2014 by Steam]
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
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macckone
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You can do what is called flame enameling.
I know very little about the process except that it
is used in jewelry making and uses enamel frit and
a blow torch.
My impression is you really need a kiln for larger items.
They do sell PTFE coatings but they have to be sintered
at about 400C. Which is not much lower than low
melting point enamels (550C).
You are probably going to need access to a kiln with
good temperature control to do those processes.
I think the kiln will cost more than larger glassware.
I also found that silicone is fairly resistant to the reactants
and products of the process you are using.
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Steam
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Yeah, probably going to have to rule out enameling for now, however I am getting a quote hasteloy B for a rxn vessel.
As for filtering off the amonium chloride, I was planing on realeasing the mixture into a large tube with a perforated end cap which I could insert
filter paper into. (Sort of like a very long buncher funnel. However instead of drawing a vacuum on the receiving side, I would add compressed air on
the filtrate side. I could remove the ammonium chloride by simply washing the tube out with water. This woild also remove any hydrochloric acid
within the tube. Since this tube wont be exposed to hydrochloric acid for very long, could it potentially be made of a stainless steel alloy?
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
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macckone
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most stainless is easily attacked by chlorides.
You should probably just buy a large capacity buchner funnel.
Polypropylene is resistant to the reaction components except
concentrated HCl. Polypropylene probably could not handle
the heat either but it would work fine for a buchner funnel.
For $15 why try to invent something you don't need:
http://www.ebay.com/itm/Polypropyelene-2-piece-Buchner-Funne...
As the filtration process required multiple filtrations even for
a kg, a 650ml is going to be sufficient. Of course you could
spend $90 and get a 2.5L.
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Steam
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ooooh thanks! That is exactly what I need!
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
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nannah
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Which electroplating can add even more resistance to corrosion of stainless steel?
I read somewhere that Caesium is used to prevent corrosion of some metals. I was talking to my next door neighbour about this yesterday, and he claims
that Cs is radioactive, but im not 100% sure about that, becouse galliumsource.com have it available for the public to buy.
/n.
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gdflp
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Some isotopes of cesium are not radioactive, and these are stable and available for sale to the public. Saying an element is radioactive is usually
not too precise due to most elements having radioactive isotopes. Just because sodium has radioactive isotopes, it doesn't mean that all sodium
chloride is radioactive. However, cesium is an alkali metal and a very reactive one. It will explode violently on contact with water much more so
than sodium or potassium. I believe that the element you are thinking of is cerium, which is a relatively cheap rare earth metal which is used in
many alloys.
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smaerd
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Can we see the sketches, or the the proposed reaction/mechanism and scale?
Personally I'm a little too lazy to crack open Vogel and guess what you are trying to do with an unknown reaction vessel material. Often times process
scale chemistry takes a different route then bench-scale for practical purposes. Chemical engineers if I'm not mistaken try to take a reaction/work-up
that has say 5-10 or so mechanical steps (boiling, filtering, distilling, etc) and do it in one or two.
Also a great resource for chemical resistance without calling for a chemical engineer would be: http://www.coleparmer.com/Chemical-Resistance?referred_id=20...
edit - also keep in mind, chemical resistance is not only based on a chemical species, it is also a concentration/temperature/pressure/time issue.
Which I am sure you know, but figured it was worth mentioning.
[Edited on 30-8-2014 by smaerd]
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Texium
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Thread Moved
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