Sciencemadness Discussion Board

SO3 from either high voltage ozone or direct arc oxidation?

Junk_Enginerd - 16-8-2020 at 06:02

I did a search, found some interesting threads, but no real conclusions...

Say I wanted to make sulfuric acid from sulfur, but I don't want to take the NO2 route, nor the V2O5 route. I read ozone will happily oxidize SO2 to SO3. Making ozone is right up my alley as an electrical engineer.

I have a DIY high voltage generator that I can push to 30-40 kV and 5-10 mA, this should be sufficient for generating usable amounts of ozone.

I also have an oxygen concentrator that puts out about 1 L almost pure O2 per minute.

Now, I also read that SO2 will directly oxidize into SO3 when exposed to an arc, if oxygen is available. So I see a few routes forward here.

Common to all routes would be a sulfur burner in a large chamber.

I could:


  1. Have a free arc in the chamber, supply O2 to the chamber.
  2. Run all the O2 en route to chamber by a silent discharge, thereby supplying the chamber with a mix of O2 and O3.
  3. Supply chamber with O2, have a silent discharge device inside the chamber


Then I suppose I could either have a volume of water/H2SO4 inside the chamber to react with SO3 as it is produced, or condense the SO3 and make oleum separately.

Which one of these routes sound like they would be most effective? Is using an electric arc or a silent discharge an effective way to get SO3?

Σldritch - 16-8-2020 at 11:01

Is ther goal Sulfur Trioxide or oleum? I think a lot depends on whether or not you can have nitrogen present in your arc, corona(no, not that kind) or not. If you do you will not get pure Sulfur Trioxide. But as for your options as you presented them i think a separate chamber for the Sulfur Trioxide is more practical. Imagine opening the chamber, sulfuric acid vapor bellowing up causing a Corona Oral Unvoluntary Gas Heaving (or C.O.U.G.H-ing as i like to call it) while the Sulfur Trioxide on the chamber walls quickly absorbs moisture from the air consuming them. I believe commercial ozone generators consists of concentric glass tubes inbetween which the ozone is generated. That sounds ideal for constructing a flow reactor. I think that is all i can say without you clarifying your goals more.

symboom - 16-8-2020 at 12:28

Well if he fed it with a pure oxygen tank it would be doable but it will take a while to make enough usable acid I think the easiest way would be to lead sulfur dioxide into copper hydroxide forming copper sulfate the do electrolysis to recover sulfuric acid the other way is the copper chloride method which makes sulfuric acid more directly.

symboom - 16-8-2020 at 12:33

Well if he fed it with a pure oxygen tank it would be doable but it will take a while to make enough usable acid I think the easiest way would be to lead sulfur dioxide into copper hydroxide forming copper sulfate the do electrolysis to recover sulfuric acid the other way is the copper chloride method which makes sulfuric acid more directly.

Junk_Enginerd - 16-8-2020 at 21:39

Quote: Originally posted by Σldritch  
Is ther goal Sulfur Trioxide or oleum? I think a lot depends on whether or not you can have nitrogen present in your arc, corona(no, not that kind) or not. If you do you will not get pure Sulfur Trioxide. But as for your options as you presented them i think a separate chamber for the Sulfur Trioxide is more practical. Imagine opening the chamber, sulfuric acid vapor bellowing up causing a Corona Oral Unvoluntary Gas Heaving (or C.O.U.G.H-ing as i like to call it) while the Sulfur Trioxide on the chamber walls quickly absorbs moisture from the air consuming them. I believe commercial ozone generators consists of concentric glass tubes inbetween which the ozone is generated. That sounds ideal for constructing a flow reactor. I think that is all i can say without you clarifying your goals more.


The goal is oleum.

The atmosphere won't be nitrogen free, I expect that there will be <5% nitrogen though. But as I understand it, the NO2 generated due to nitrogen will probably only help and catalyze, while not being a sigificant contaminant at these levels.

I can deal with a face full of sulfuric acid, though I'm not too worried since it'll hardly be running at temperatures high enough to make significant vapors. Mist maybe, but that's easily avoided by not sticking my face in there while it's operating.

Yes, concentric glass tubes sounds like a silent discharge arrangement.
Quote: Originally posted by symboom  
Well if he fed it with a pure oxygen tank it would be doable but it will take a while to make enough usable acid I think the easiest way would be to lead sulfur dioxide into copper hydroxide forming copper sulfate the do electrolysis to recover sulfuric acid the other way is the copper chloride method which makes sulfuric acid more directly.


I've tried the electrolysis method and I didn't really like it. Too much opportunity for impurities to remain...

Copper chloride you say? Haven't heard of that one. I have jugs of copper chloride waste from NO2 production. I'll check it out.