Sulfuric acid from Ammonium sulfate?

[Nitric-producer]

I Just tried a search and could not find anything previously posted about this, so here goes!

Read a while back that Sulfuric acid, and Ammonia, can be prepared by dissolving Ammonium Sulfate in concentrated Sulfuric acid. If I remember correctly the salt will decompose below Sulfuric acid's boiling point, into gaseous Ammonia, and liquid sulfuric acid (in addition to original acid). This is good for me because I can get Ammonium Sulfate OTC and quite cheap.

I just tried a simple experiment in my distallation apparatus. The salt seemed to dissolve, and I tried to collect the gas, but the acid bumped badly and spewed into my collection beaker. :(

After which the experiment was abandoned. I plan on scaling this up, possibly in a stainless steel beer keg? (unsure if this will corrode)
Has anyone else ever heard of this reaction or tried it? It gives a cheap, plentiful supply of ammonia and Sulfuric acid! :D

[Nitraptor]

You can't collect ammonia gas that way because sulfuric acid is also breaking down to SO3 and H2O at the (NH4)2SO4 decomposing temperature.

You must somehow separate the NH3 from VERY hot mix of SO3, SO4, H2O,NH3.

[Nitric-producer]

At this temperature, will there not be an equilibrium of NH3, H2SO4 and
(NH4)2 SO4 ?

[Charles Owlen Picket]

(of course, use some bump stones, etc)
I think I know where you're going with this .....what sort of condenser did you have on the distillation rig? Ammonium sulfate is some useful material. I have certainly heard of simple ways of getting anhydrous ammonia, etc via sodium hydroxide. Was there a vacuum on it?

[NoltaiR]

I understand you are trying to find a proper procedure for this, but isn't sulfuric acid pretty easy to attain? I have always just bought it from Lowe's in the 93% form.

[nightandday]

@Nitricproducer

Probably it´s not possible to separate the gaseous mixture (SO3 + H2O + NH3) produced by heating ammonium sulfate. But, by addition of oxygen (air) to this hot mixture , the ammonia is oxidized (2 NH3 + 3 O2 -> N2 + 6 H2O) and you will get a mixture of SO3, H2O and N2, which on cooling will give H2SO4 + H2O (i.e. diluted H2SO4) and N2.

[Nitric-producer]

Just found this, a bit vague though, and I cannot find the actual patent:

http://www.freepatentsonline.com/EP1444166.html

[nightandday]

Here is some literature in PDF form about that:

http://rapidshare.com/files/45936186/NH4_HSO4_dec.zip.html

You need only a simple distillation apparatus to check whether the claims in that patent are right.

[Nitric-producer]

Nightandday : Very informative post there, the literature helped a lot!

Does anyone know whether 99% Sulfuric acid would corrode a stainless steel beer keg?

I have a couple of peltier's rated to -30*C ambient temperature, so I reckon if I cooled the heatsink on them with an ammonium nitrate ice bath, I could easily liquefy the ammonia, and then bottle it! :D

[Charles Owlen Picket]

Stainless steal should hold up. HCl does a job on stainless but not H2SO4 or HNO3 - however then we would need to qualify what type of stainless....it would need to be high chrome, etc....there are some materials that are "rust resistant" and some that are "stainless", etc, etc. But basically mostly I have not seen that which is purported to be SS to break down with H2SO4. You MAY get some roughening over time. Glass is very easy to obtain; why take a chance?

[megalomania]

Search google for chemical compatibility charts. I found a few...

Type 304 stainless steel is commonly used for chemical processing equipment, for food, dairy, and beverage industries, for heat exchangers, and for the milder chemicals.

Type 316 stainless steel contains molybdenum to control pit type attack so it is slightly more corrosion-resistant than Type 304 stainless steel. Type 316 is ideal for chemical and pulp handling equipment, for photographic equipment, food and beverage processing and for dispensing equipment and equipment that will be exposed to salt water.

According to the Cole Parmer website...
Sulfuric acid 10%: both 304 and 316 are rated as "questionable"
Sulfuric acid 75%: both 304 and 316 are rated as "unsatisfactory"
Sulfuric acid fuming: both 304 and 316 are rated as "unsatisfactory"

According to the Hayata website...
Sulfuric acid 10%: 304, D-Severe Effect; 316, B-Good
Sulfuric acid 10-75%: both 304 and 316 are rated D-Severe Effect
Sulfuric acid 75-100%: 304, C-Fair; 316 D-Severe Effect
Sulfuric Acid (cold concentrated): 304, C-Fair; 316 B-Good
Sulfuric Acid (hot concentrated): 304, D-Severe Effect; 316, C-Fair

Try the selection of chemical compatibility guides compiled at http://www.grayledge.com/ChemicalCompatibility.html

It does not look like steel is suitable with concentrated sulfuric acid, at least the common alloys I listed.

[nbk2000]

For oleum, 25%, which is what I figure is the actual product prior to dilution, I found this:


Hastelloy-C A-Excellent
Kalrez A-Excellent
Kel-F A-Excellent
PPS (Ryton) A-Excellent
PTFE (Teflon) A-Excellent
Viton A-Excellent
304 stainless steel B-Good
316 stainless steel B-Good
Aluminum B-Good
Bronze B-Good
Fluorocarbon (FKM) B-Good

At 100%, only aluminum and Fluorocarbon were B-Good, everything else being destroyed. With Sulfuric Acid over 75%, many materials were compatible, but only Fluorocarbon is compatible with both SA and Oleum, so that's it right there.