SO2 + O2 catalyst

[pHzero]

Hey there, I'm looking for a catalyst other than V2O5 which can be used to catalyse the reaction:

2SO2+O2-->2SO3

 

So far I've considered....

 

FeO, I think something like this might happen:

FeO is unstable below about 800 centigrade, so 3FeO <--> Fe2O3 + Fe

4Fe + 3O2 --> 2Fe2O3

Fe2O3 + SO2 --> SO3 + 2FeO

 

But I'm also worried that this might happen:

2Fe2O3 + 6SO2 + 3O2 --> 2Fe2(SO4)3

 

 

 

I also thought about using manganese dioxide:

MnO2 + SO2 --> MnSO4 (I'm sure this bit's correct, wikipedia says so xD)

MnSO4 --> SO3 + MnO (That's a hypothetical thermal decomposition reaction... not sure if that takes place)

2MnO + O2 --> 2MnO2 (ditto)

 

 

And copper (ii) oxide:

2CuO + SO2 --> Cu2O + SO3

2Cu2O + O2 --> 4CuO

 

 

Does anyone know if any of these will work? Or any others which will work?

[mr.mechanics]

:-)brother,

i've read that metallic sulphates (like ferric sulphate above), at high temp give up metallic oxide and sulphur oxides.

thus, i suppose that the reaction you fear of, might not take place in the forward side.

dont know whether the original reaction might take place.

why dont you check out the electochemical series to get a better combo??

you might land into something which is more sure..

reply if you get something from there.

toodles..

:cool:

[pHzero]

Hmm... is that another name for the galvanic series? And what am I looking for, reactive or unreactive?

I thought I just wanted a metal oxide which readily gives up its oxygen then gains it back upon reaction with elemental oxygen

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Wait... I just thought... do I even need to convert the SO2 to SO3? If I dissolve SO2 in water and bubble oxygen through it, wont the production of SO3 be thermodynamically favourable due to the high exothermicity of the hydration of SO3? Then that leaves you with an H2SO4 aerosol which you can cool in a condenser.

Edited April 10, 2009 by pHzero
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[UC]

no, no and no.

 

Ferric sulfate can indeed eject SO3 at high temperatures, but this requires fused quartz apparatus and at those temperatures, SO3 substantially decomposes to SO2 and O2. The most workable method for SO3 is decomposition of sodium bisulfate, as seen on sciencemadness.org.

 

SO2 will not substantially oxidize in water, and bubbling O2 through it will fill the room with SO2 instead.

 

electrochemical series is largely useless here. V2O5 is a pretty strong oxidizer and is used for a reason. It's very sensitive to preparation methods (overheating makes it useless) and works best in a molten flux of cesium and potassium sulfates on a porous catalyst support, IIRC.

 

You might want to try the "lead chamber" process, which involves burning sulfur mixed with KNO3 in a sealed container, within a larger container with some water in the bottom. The small amounts of NOx formed catalyze the oxidation of SO2 to SO3 by O2. SO3 dissolves in the water to produce dilute sulfuric acid.

[pHzero]

no, no and no.

 

Ferric sulfate can indeed eject SO3 at high temperatures, but this requires fused quartz apparatus and at those temperatures, SO3 substantially decomposes to SO2 and O2. The most workable method for SO3 is decomposition of sodium bisulfate, as seen on sciencemadness.org.

 

SO2 will not substantially oxidize in water, and bubbling O2 through it will fill the room with SO2 instead.

 

electrochemical series is largely useless here. V2O5 is a pretty strong oxidizer and is used for a reason. It's very sensitive to preparation methods (overheating makes it useless) and works best in a molten flux of cesium and potassium sulfates on a porous catalyst support, IIRC.

 

You might want to try the "lead chamber" process, which involves burning sulfur mixed with KNO3 in a sealed container, within a larger container with some water in the bottom. The small amounts of NOx formed catalyze the oxidation of SO2 to SO3 by O2. SO3 dissolves in the water to produce dilute sulfuric acid.

 

Problem with that is, i don't have a sealed lead chamber, and i don't have the equipment to make one. I've got an old lead acid battery i could take apart to get hte lead out of but no way of welding it. (I'm only 16 xD)

But perhaps I could combine the contact process and lead chamber process?

I'm thinking, instead of V2O5 catalyst, run the SO2 through XNO3 to oxidise it, a bit like you recommended. It'd get used up but I guess thats something i could live with.

What gets left over when XNO3 oxidises something? Do you get XNO2 + O, XO+N2+O or something else?

Once I've got the SO3, the rest is easy. I can bubble it through concentrated sulphuric acid to get oleum.

[UC]

Problem with that is, i don't have a sealed lead chamber, and i don't have the equipment to make one. I've got an old lead acid battery i could take apart to get hte lead out of but no way of welding it. (I'm only 16 xD)

But perhaps I could combine the contact process and lead chamber process?

I'm thinking, instead of V2O5 catalyst, run the SO2 through XNO3 to oxidise it, a bit like you recommended. It'd get used up but I guess thats something i could live with.

What gets left over when XNO3 oxidises something? Do you get XNO2 + O, XO+N2+O or something else?

Once I've got the SO3, the rest is easy. I can bubble it through concentrated sulphuric acid to get oleum.

 

You can run it in a big plastic container; see here: http://www.sciencemadness.org/talk/viewthread.php?tid=2824

 

[ce] NO2 + SO2 -> NO + SO3 [/ce]

[ce] 2NO + O2 -> 2NO2 [/ce]

 

SO3 is pretty horrible stuff, as are nitrogen oxides, and not to be taken lightly.

[pHzero]

Ah that sorta makes sense. Do you know if it matters if I use H2SO4 as the solvent instead of water, so I get H2S2O7 rather than dilute H2SO4? I've still got a litre of so of 98% which mum bought home from work for me

 

And yeah, I'll be careful mum gets really pissed off when i fumigate the house with anhydrous acid gases (she wasnt happy when i filled the house with HCl). I'll do it outside. While my parents are at work.

xD

 

I should probably order some nitrate now

[UC]

Ah that sorta makes sense. Do you know if it matters if I use H2SO4 as the solvent instead of water, so I get H2S2O7 rather than dilute H2SO4? I've still got a litre of so of 98% which mum bought home from work for me

 

And yeah, I'll be careful mum gets really pissed off when i fumigate the house with anhydrous acid gases (she wasnt happy when i filled the house with HCl). I'll do it outside. While my parents are at work.

xD

 

I should probably order some nitrate now

 

You can't use conc. H2SO4 for absorbing the SO3, because it will suck up the NO and NO2 to form nitrosylsulfuric acid: http://en.wikipedia.org/wiki/Nitrosylsulfuric_acid. IIRC, H2SO4 also dissolves SO2 pretty well.

 

You see, a 1:1 mix of NO and NO2 dissolved in water is nitrous acid, so we can expect the following to occur readily:

 

[ce] NO + NO2 + 2H2SO4 -> 2NOHSO4 + H2O [/ce]

[pHzero]

That gives me another idea (Btw I'm not saying your suggestions are bad or arguing... I hope it doesnt seem that way. I'm just brainfarting about how to improve the method.)

If SO2 is soluble in H2SO4, maybe a variation on my idea of pumping SO2 into water might work.

Burn sulphur. Bubble the SO2 thats produced through some H2SO4, along with excess O2. Unless I'm mistaken, SO3 always forms in tiny amounts in equilibrium with SO2+O2. When it forms SO3, that will react with the sulphuric acid to form H2S2O7. The loss of the SO3 will then drive the reaction further to the SO3 side and eventually all of the SO2 will oxidise to SO3.

 

Sorry if i seem like a complete idiot, I've only been doing chemistry for a few years.. Its because I am

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Edit:

One word. Ozone. Discuss.

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Another edit:

This website says that you can just react SO2 with ozone to make SO3: http://www.ucc.ie/academic/chem/dolchem/html/comp/so3.html

 

Sorry for the triple post

[bob000555]

Vandium pentoxide is the way to go

http://en.wikipedia.org/wiki/Vanadium_pentoxide#Sulfuric_acid_production

It is avalable here:

http://www.unitednuclear.com/chem.htm

[pHzero]

Yeah, V2O5 would be great, but unfortunately theres nowhere in the UK which sells it to private individuals. I'm surprised united nuclear can sell it, along with mercury and sulphuric acid when theyve actually gone so far as to practically ban an element (iodine) in the US (woop, over here we can but 10kg of iodine and nobody cares )

[gonelli]

...they've actually gone so far as to practically ban an element (iodine) in the US (woop, over here we can but 10kg of iodine and nobody cares )

 

I hope they haven't stopped using iodine in foods/salts, because that would mean a whole lot more people walking around with goitres!

[pHzero]

I hope they haven't stopped using iodine in foods/salts, because that would mean a whole lot more people walking around with goitres!

 

Haha no, they still iodise salt, but if you buy over a certain amount of iodine (i think its 30mg) in any form (elemental, iodide, iodocarbons etc), you get reported to some investigations beaureau cause its used in the red (phosphorus), white (ephedrine) and blue (iodine) process of making methamphetamine.

[UC]

Haha no, they still iodise salt, but if you buy over a certain amount of iodine (i think its 30mg) in any form (elemental, iodide, iodocarbons etc), you get reported to some investigations beaureau cause its used in the red (phosphorus), white (ephedrine) and blue (iodine) process of making methamphetamine.

 

That's a load. a $1 bottle of 2% iodine tincture has about a gram on iodine in it, IIRC. Now buying a kilo of iodine off ebay is another story, and may well get you reported to some agency or another. Technically, it's not illegal to own at all, in any quantity, though. The same is true with pseudoephedrine cold medicine. It's not illegal, just really sketchy to buy lots of it. The only thing that's truly illegal is making the drugs.

 

V2O5 really isn't the way to go. I'd say that the folks on sciencemadness (the ones that aren't morons and cooks) are some of the best amateur chemists out there. They've stopped trying to use V2O5 for a reason. It's just not very amenable to scale-down at all, though it works great in a huge plant where you have precise reactor controls and a continuous production system.

 

Ozone would work, but it's not pleasant to work with either.

 

Bubbling O2 through SO2/H2SO4 will do nothing. I don't think you make much "pyrosulfuric acid" (maybe a small amount of equilibrium product) so much as a solution of SO3 in H2SO4. The energy barrier for [ce] 2SO2 + O2 -> 2SO3 [/ce] is just too high to overcome without a catalyst.

Edited April 12, 2009 by UC