Sulfuric acid from Ozone?

[Nitric-producer]

From my hours of researching the use of Ozone in the production of Nitric acid, I came across this:

S + H2O + O3 → H2SO4
3 SO2 + 3 H2O + O3 → 3 H2SO4

It got me thinking about a way for the home experimenter to produce high purity Sulfuric acid. Those of you who can get your Sulfuric acid easily may think this is stupid. However this may be helpful for people who have difficulty getting chemicals.

The top equation looks good, I am thinking of a big container filled with water and Sulfur and Ozone gas bubbled through - with possible agitation from a magnetic stirrer. Anyone think this could work? Comments appreciated.

[Grapes Of Wraith]

Sulfur doesn't dissolve in water, would you have it floating on top? or are you talking about SO₂ ?

3 SO2 + 3 H2O + O3 → 3 H2SO4
This doesn't make sense, is the ozone a catalyst? if so it should be:
3 SO₂ + 6 H₂O + O₃ → O₃ + H₂SO₄
but then again thats the regular sulfuric acid formula except with ozone as a catalyst.
or it could be something else I am to lazy to write.

[megalomania]

Anyone care to conjecture as to the rate of reaction of forming sulfuric acid from a mixture of water, ozone, and sulfur? I can't imagine it would be very high, so this reaction might just be a theoretical curiosity without practical applications. Of course what is unsuitable for industry is not necessarily unsuitable for us. I have plenty of time to let a mixture sit for weeks if need be.

Perhaps the solubility of sulfur, and the resulting rate of reaction, could be increased by adding a suitable solvent also miscible with water. The presence of ozone and sulfuric might also affect the solubility of sulfur.

This reaction is at least easy enough to prove through experimentation since the reagents and conditions are within the reach of many Forumites.

What source did you locate that gave that reaction, Nitric-producer?

[Alexires]

Grapes Of Wraith - Although sulfur itself may be insoluble in water, it could be oxidised to SO2 (using O3) where it reacts with H2O to form H2SO3 and then further oxidised with O3 to H2SO4.

The latter part of this is supported by this from wikipedia

"Sulfuric acid is a constituent of acid rain, being formed by atmospheric oxidation of sulfur dioxide in the presence of water - i.e. oxidation of sulfurous acid. Sulfur dioxide is the main product when the sulfur in sulfur-containing fuels such as coal or oil is burned."

I think perhaps it would be better to burn the sulfur (easily done) and then perhaps a glow discharge from a NST or an ignition coil on the way to the nitric acid generator would be enough to oxidise it with atmospheric O2. Suppose there is no real way to know but to try.

[Microtek]

Nitrogen oxides catalyse the oxidation of SO2 to SO3 by atmospheric oxygen. The reaction is still not extremely fast, so you would need to device a way to get long residence times for gaseous reactants. Possibly a long plastic tube where the SO2 and the NOx are steadily fed into one end and the product taken out at the other. The tube would need to be quite unreactive since SO3 is rather aggressive if any water is present.

[Grapes Of Wraith]

yes, this formula makes perfect sense now thank you Alexires.

[Nitric-producer]

I wanted information on ozone, so I got the reaction from Wikipedia. I am not sure how accurate it may be. Unfortunately I dont have any Sulfur at the moment :(

[FUTI]

Burning sulfur to SO2 and passing resulting gas through H2O2 solution is still simplest idea IMHO.

NOx is old (but still used by some firms) industrial scall procedure. It works perfectly as much as I remember when we done that in students lab. Can be simulated with OTC items IIRC(copper wire, little HNO3, little old H2SO4, couple of pipes, aquarium pump, air, few dropping funnels with glass beads to augment the conntact surface, couple beakers).

If you rigged that NOx/ozone forming device mentioned in other thread to make both you can be onto something...

[Nitric-producer]

What I am now thinking of is the Nitric reactor exhaust hooked up to a second chamber, filled with burning Sulfur! The SO3 then leaves through another pipe into some water. Although I have heard this reaction is explosive :eek: . Anyone seen SO3 reacting with water? I know industrially they bubble SO3 through Sulfuric acid.

[Microtek]

The SO3 + H2O --> H2SO4 reaction is very exothermic and tends to produce a fine mist of sulfuric acid which is very difficult to condense; think smoke. It is obviously extremely hazardous to inhale the mist and it is very corrosive. I think you should absorb the SO3 in concentrated sulfuric acid as they do industrially. Oleum is much more valuable than sulfuric anyway, and you can always dilute the oleum to whatever concentration you need.
Before you get that far though, you need to makes sure that the SO2 --> SO3 oxidation has time enough to take place. I suggest giving the SO2/air/NOx mixture a residence time of about 5 min before leading it into the absorber. The actual reaction rates will depend on all the usual variables of course.

[Alexires]

Bypass the O3 step and just use H2O2 with SO2.

I'm going to try that (as soon as I can work out how to jury rig something to do what I want it to).....

Oooooh, have a look at this (http://www.h2o2.com/intro/overview.html) (oxidizing potential).

If everyone knew this, forgive me, but I have a feeling that this could be a very good idea (if you can find H2O2). This way, we could bypass trying to turn SO2 into SO3 and solve the heating/cooling problem (as in, is it better to heat or cool to achieve maximum yield).

I'll post back with results.

[Nitric-producer]

The only reason for using Ozone, rather than H2O2, is because everyone can make Ozone at home with relative ease. H2O2 can be difficult to acquire.

[Alexires]

Right now, there is some sulfur being melted and oxidized to SO2 then being passed through 50% H2O2. Unfortunately, it seems my bubbling stone doesn't like a) Sulfuric acid (if it's being produced) or b) 50% H2O2.

Nothing too interesting to report at the moment. I might leave the set up running overnight then extract a 10ml sample and compare its density to 10ml of the pure 50% H2O2.

A very rough set up. If it does work, I will take a picture of it and post for those interested.

[Microtek]

I can think of another reason: With H2O2 the concentration of the produced sulfuric acid is limited by the concentration of the peroxide. With O2 or O3 you can produce 100% H2SO4 or even fuming sulfuric acid (Oleum).

[Alexires]

Urgh *frown*.

Mechanical failure. I wasn't pumping enough air into the chamber and had a whole bunch of sulfur atomize(?) and then stick to the inside of the bubbler tube, effectively blocking it.

I don't know if it produced any H2SO4 and I don't have anything to test it. What a pain in the ass. I was hoping to have it work for a couple of days and do a density test....

I think that perhaps ozone would be the way to go (in hindsight) *laugh*.

More money outlay *smile*.

Thanks anyway gents, for all the help.

[Nitric-producer]

Good job on trying anyway! If you get it working again, you could try a simple "reaction test". Basically mix your acid with an alkali or similar and note what happens. This will give you an idea of what you have made.

I plan on trying something on this soon...

[Alexires]

Nitric-producer - Yeah, thats what I meant by not having anything to test it with. I only have alkali metal compounds lying around, and the sulfates of those are all soluble in water.

See if I can find some CaO somewhere.

[Nitric-producer]

I have been away from the forum for some time due to having University exams. I am now back on to some of my projects. Anyone had any success with this? I need to buy some Sulfur.

[Nitric-producer]

Ok, I have had some new idea's. The Sulfur is burned in a combustion chamber and the SO2 gas is mixed with Ozone (from Ozone generator). Both gases travel through a long coil of fine pipe. This gives them time to react.
(All gases entering the reaction vessel would be dried using a dessicant)

The gases are cooled in the next chamber, using a thermoelectric cooler or similar. Sulfur trioxide (melting point: 16.9*C) would solidify in the bottom of the container. Any unreacted Sulfur dioxide (boiling point: -10*C) would become liquid and could some how be recirculated back into the reaction coil. This maximises yield. Any other gases, for example oxygen, would simply leave the container as a gas. The SO3 can then be reacted with either water or H2SO4.

The above assumes a minimum temperature of -10*C can be achieived. I have no idea if this will work, or how dangerous it might be. Comments?

[Cindor]

Why would you want to have liquid SO2 if you use it like a gas?
Just keep it that way: makes it easier

The reaction of SO3 + H2O is very exothermic, that's why SO3 is mixed first with SA to form oleum, then the oleum reacts with water to make SA (H2SO4 + SO3 ---> H2S2O7 + H2O ---> 2H2SO4)

[Nitric-producer]

The only reason for changing the states of the gases, is for seperation purposes. However I still do not know if this will work.

[megalomania]

Yes, Cindor, that's the reaction, but what if only 50%, 20%, or less than 10% of your SO2 is reacted with ozone to form SO3? You are making tons of useless sulfurous acid with only a little sulfuric acid mixed in. By separating the unreacted portion and reintroducing it into the reaction chamber we can maximize our yield. That's the chemical engineering way.

I don't suppose there is any relevant patent literature on the separation of sulfur dioxides and trioxides is there? They might reveal an effective solution.

Does anyone know if ozone will decompose sulfur trioxide, and if so will it do so rapidly or with difficulty? If sulfur trioxide is not adversely affected by ozone, you could set up a recirculator in the gas phase to recycle the gas over and over for a period of time (determined experimentally for your device) that exposes unreacted sulfur dioxide to more ozone. The % trioxide should increase with each pass until it is acceptable. Then you have to decide how do you add more ozone in a closed system? Do you expose the SOx gasses to the ozonator, do you pressurize the system, do you add the ozonated air separately? If you did liquefy the system entirely you could you could do multiple batches where each batch is exposed to fresh ozone and becomes a higher % SO3.

[Cindor]

Haha, I dream about (no, I really did it) an aquarium oxygenator used to reflux gases, it was inside flask and connected to the O3 generator.

But I don't think it can take it with that much oxidizers....