Sciencemadness Discussion Board - Making H2SO4 from sulfur & O2 concentrator?

Making H2SO4 from sulfur & O2 concentrator?

RogueRose - 29-5-2018 at 03:00

Ok so with the new EPP ruling that is absolutly ridiculous about banning 15% H2SO4 there needs to be an easy way to make high concentration H2SO4 at home and I've toyed with this idea for a while, tested a few aspects and think there is some serious potential to this method, though refining it (with help of members) could help a good bit.

So we all know sulfur is usually easily accessible and buying flowers/flours of sulphur at the garden center is a very cheap place to get sulfur (here it is $6-10/50lbs and it is very fine and extremely pure). It does burn well once it is lit properly and we know that the gas produced is SO2 which doesn't make H2SO4 directly when mixed with water, though it can in some cases as it can oxidize to SO3 on the way to the water.

What I am proposing is using something like an O2 concentrator (decomissioned medical units that produce 5L/min at about 80-92% pure O2 - These are often available for $50 or so online and the glass blowing community useses them a lot to produce O2 for high temp glass melting).

So what I am proposing is using the output of the concentrator as the oxidizing catalyst for the SO2. 2SO2 + O2 -> 2SO3 + heat, then SO3 + H2O -> H2SO4 + heat.

What needs to happen is that the sulfur needs to be lit in a container that allows either atomspheric air in to burn, or a portion (say 10-20% by way of reducing orofice opening) of the pure O2 to burn the sulfur. Then using an aspirator/venturi pump, connect the remaining 80-90% of the O2 into the venturi pump as the "drive" or compressed gas which while it moves through the venturi it pulles the SO2 from the burn chamber up into the pump where it mixes with the purish O2 and oxidizes to SO3. This gas is them forced down through water where it makes H2SO4.

If the pressure from the pump isn't sufficient, then it may be necessary to add a vacuum pump into the receiving container to lower the pressure in the container a few PSI. The incoming SO3 is bubbled under the water and the vacuum pump pulls air from above the water, allowing the flow of SO3 to more easily be pulled into the water. Another option is to add some kind of booster pump to the 80-90% (by volume) of the O2 that drives the venturi, stepping up the pressure, which increases the vacuum in the burn chamber and increases the pressure forcing the SO3 down into the water. IDK which method would be easier, I suspect the vacuum method would be easier especially if you have a vacuum pump already and can set it for a certain PSI rating. Thoughts?

Now as for the burn chamber, this could have many designs. One could be a 2 neck flask where a glass tube could be used to direct the O2 or atmospheric air down onto the burning Sulfur and then the gasses could be vented up out of the other neck. Now just the fact that O2 is being pumped into the vessel and S is being converted into a gas, there should be increased pressure in the tank driving the SO3 up out of the other neck. I need to think a little more about the reaction vessel setup but I think something interesting could be setup out of commonly available items.

Another option if you have H2O2 available (especially at 30-35%) would be to just burn the S in air, use a venturi pump with normal compressor/air, and direct the SO2/SO3 mixture (as the SO2 should oxidize with the 21% O2 in the air of the venturi pump, especially since the flow ratio of "drive fluid/air" to SO2 would be something like 3-6:1, giving plenty of O2 with which the SO2 can react to produce SO3.

Another option is to use an O2 concentrator and use a compressor to store the O2 to use with the venturi pump.

I think something like this could easily be done. I do wonder if the temp for the SO2-SO3 conversion needs to be any special temp, if higher temps are preferred or if 100-200F is sufficient (as the burning of the S would produce these temps). A long reaction tube could be constructed out of some 2'-5' boro glass tube to give plenty of room for the gasses to mix and maybe at .5" or 12-13mm ID that would be plenty of volume to give time for the adequate mixing of the gasses.

Anyway, this is just a though and I think it could work well and I'd like to try this in the next few weeks if I can find an O2 concentrator for a good price.

I'd like to hear anyones input on what they think about this, how it could be improved, where you think there may be shortfalls, etc.

Edit: I've also been looking (again) into the use of O3 generators which use O2 concentrators as the source for the gas. this removes most of the N2 which would be oxidized to NO2/NO3 in this situation messing up a lot of the reaction. There are many O3 generators that can be purchased and even better ones can be built for relatively little money (mostly scrap parts with a few specifically purchased parts to enhance unit longevity). Most chinese O3 units say they produce 2-5g/hour and these are $10-20 each but i've spec'd out parts to produce units that produce 20-30g/hr for maybe $40-50 w/o a power supply (add another $10-30 depending on what is available to you).

IDK if O3 will directly oxidize S to SO2 or SO3 from the powder form (maybe if heated to 200-250F?) but that would reduce a lot of cumbersome issues. It is possible to direct the output of the O3 generators into glass piping so it doesn't escape to the reaction room (still best done outside or in a good fume hood though fume hood will degrade with O3, so outside is best). I plan to re-examine the production of a good O3 genny again and see what I can come up with if this method may be more beneficial than the above method.

[Edited on 5-29-2018 by RogueRose]

Ubya - 29-5-2018 at 04:15

why not just burn sulphur in a stream of pure oxygen and then let the gases through the catalyst? (oxygen would be in excess after the combustion with sulphur)

SWIM - 29-5-2018 at 06:15

The whole burning something in the glassware part sounds like the engineering headache here.

If you drop H2SO4 into molten sulphur at the right heat, won't each 2 molecules of acid produce 1 of SO2 while being reduced themselves?

Then you'd get SO2 as a (fairly) pure gas at a controllable rate. Although only 1/3 of the SO2 molecules would make new sulfuric acid, the oxygen usage per mole of acid made would be the same.

You'd put a liter in, and get 1.5 liters, or nearly, out.

If you used a liter of store-bought drain cleaner acid at 91% and dried the air you'd end up with H2SO$ at around 100% without distilling because the excess water in the cheap acid would be taken up to make the new acid being produced.

What if you just buy a tank of O2 and feed it into a closed flask along with SO2 and wait?

UV is supposed to catalyze SO2 oxidation, don't know what effect just shining 250nm, or 180nm on sulfur in an oxygen environment would have, but it would be worth a bit of research if it can be made to work.

I believe the shorter UV wavelengths will also generate ozone.

Swinfi2 - 29-5-2018 at 06:45

After doing some googling and looking for info about why the contact process works the way it does I learned a few things.

Your 2SO2 + O2 -> 2SO3 does happen at room temp just exceptionally slowly; temperature helps but works against the thermodynamics.

Often the catalyst used (V2O5) is an oversimplified version; they actually use a mixture of 1:2 V2O5 and K2SO4/K2S2O7 supported on silica gel etc., why? this mix melts at about 490C (according to chart in the paper) increasing its activity over an order of magnitude. The SO3 also dissolved in the catalyst creates some hysteresis in the catalytic activity by depressing the melting point.

Challenge: How can we push this melting point down even further?

but doing it this way requires Vanadium, and idk where an easy/otc source of that is.

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RogueRose - 30-5-2018 at 06:44

Quote: Originally posted by Swinfi2

After doing some googling and looking for info about why the contact process works the way it does I learned a few things.

Your 2SO2 + O2 -> 2SO3 does happen at room temp just exceptionally slowly; temperature helps but works against the thermodynamics.

Often the catalyst used (V2O5) is an oversimplified version; they actually use a mixture of 1:2 V2O5 and K2SO4/K2S2O7 supported on silica gel etc., why? this mix melts at about 490C (according to chart in the paper) increasing its activity over an order of magnitude. The SO3 also dissolved in the catalyst creates some hysteresis in the catalytic activity by depressing the melting point.

Challenge: How can we push this melting point down even further?

but doing it this way requires Vanadium, and idk where an easy/otc source of that is.

I can get a lb of V2O5 for about $60 + shipping and maybe for $20-30 for 1/4 lb. IDK if that is a good price, I never had the desire or need to buy it.

VSEPR_VOID - 30-5-2018 at 06:58

Quote: Originally posted by RogueRose

I can get a lb of V2O5 for about $60 + shipping and maybe for $20-30 for 1/4 lb. IDK if that is a good price, I never had the desire or need to buy it.

And in 10 years vanadium oxides are banned along with the burning of sulfur. The government of the UK might just decide to ban distillation, round bottom flasks, or beakers.

https://www.youtube.com/watch?v=7SDHeTcOXtI

Cody's Lab made a video about making sulfuric acid. He generated his sulfur dioxide without burning sulfur but I think he used sulfuric acid to do this.

If you had an oxygen concentrator, if you even need that for what I am proposing, you could load a large pipe or chamber with sulfur and pass oxygen through it. If you used an excess of oxygen there would be no need to add it later.

RogueRose - 30-5-2018 at 07:02

Quote: Originally posted by VSEPR_VOID

Quote: Originally posted by RogueRose

I can get a lb of V2O5 for about $60 + shipping and maybe for $20-30 for 1/4 lb. IDK if that is a good price, I never had the desire or need to buy it.

That is an excellent idea! I suggest maybe even a quartz tube as the temp's won't ever come close to weakening it. Maybe an old Halogen light if you don't need a lot of space. I have lights 7" long by 1/2" OD that may be suitable.

VSEPR_VOID - 30-5-2018 at 08:34

Almost anything should work. I bet that the cheapest option will be a metal pipe a foot or so long depending on how much you want to make, at what rate, and of what quality. After the pipe channel the hot gasses through some copper piping and water to cool it then allow it to be diffused into peroxide or cold water. The whole set up could not cost more then 30-50 dollars. The chemicals are also dirt cheap. To concentrate the final product filter it to remove non-oxidized free sulfur then boil/distill. The excess peroxide in solution will destroy any organic contaminants.

clearly_not_atara - 30-5-2018 at 09:44

Are bisulfate salts banned? If you're willing to fuck with SO3 you might as well just go that route.

KHSO4 + 300 C >> K2S2O7 + H2O (g)

K2S2O7 + 400 C >> K2SO4 + SO3 (g)

Also unlike SO2, bisulfite HSO3- can be oxidized efficiently by H2O2 IIRC.

DavidJR - 30-5-2018 at 10:13

Quote: Originally posted by clearly_not_atara

Are bisulfate salts banned? If you're willing to fuck with SO3 you might as well just go that route.

KHSO4 + 300 C >> K2S2O7 + H2O (g)

K2S2O7 + 400 C >> K2SO4 + SO3 (g)

Also unlike SO2, bisulfite HSO3- can be oxidized efficiently by H2O2 IIRC.

Fortunately no, at least, not yet. I could buy a 25kg bag of NaHSO₄ for about £50 (from mistralni), so pretty cheap really.

[Edited on 30-5-2018 by DavidJR]

XeonTheMGPony - 30-5-2018 at 17:02

Quote: Originally posted by Swinfi2

but doing it this way requires Vanadium, and idk where an easy/otc source of that is.

Look at some old mechanics wrenches or sockets, tools are usually made of drop forged vanadium

All you need to do is strip the chrome from them then dissolve and oxidize it.

NEMO-Chemistry - 31-5-2018 at 07:29

Quote: Originally posted by XeonTheMGPony

Quote: Originally posted by Swinfi2

but doing it this way requires Vanadium, and idk where an easy/otc source of that is.

Look at some old mechanics wrenches or sockets, tools are usually made of drop forged vanadium

All you need to do is strip the chrome from them then dissolve and oxidize it.

I had always assumed Chrome Vanadium tools were talking about vanadium being in with the chrome, it never occurred to me the actual tool was vanadium.

Sorry for asking this but, are you sure the actual tool is vanadium? It isnt i dont believe you, but i have been after some for a good while, i cant believe its been under my nose all this time.

DavidJR - 31-5-2018 at 07:52

Quote: Originally posted by NEMO-Chemistry

No. They are made from steel having chromium/vanadium as additives. However they are still mostly iron. Apparently the addition of chromium/vanadium increases the effect of hardening. And chromium is probably what stops them from rusting, like stainless steel.

XeonTheMGPony - 31-5-2018 at 19:48

well these where very expensive sockets and claimed to be dropped forged vanadium, and when the chrome flaked off the metal was not like iron at all

and it was stamped on it, but I could see it as an alloy

[Edited on 1-6-2018 by XeonTheMGPony]

AJKOER - 1-6-2018 at 13:44

The issue is that ordinary oxygen is just not reactive enough!

So, one possible solution but not likely large scale, would be to introduce a more reactive oxygen specie (see, for example, https://en.wikipedia.org/wiki/Singlet_oxygen).

Research on SM and elsewhere for a convenient and perhaps cheap (if a factor) way to prepare singlet oxygen, where dry O(1P) has a half-life of just more than an hour in air (per a source, "It is reported to have a half-life of microseconds in solvents and 72 minutes in air at ambient temperature, https://chemistry.stackexchange.com/questions/8124/how-do-i-...).

Then, light your moisture free sulfur on fire in air and move it to an atmosphere of singlet oxygen with an excess of dry O2. Reaction:

S + Heat + O2 + O(1P) --> SO3

In a couple of hours (waiting for the degradation of the singlet oxygen, or introduce a fine water mist) collect the SO3, which one could keep or just add water to create sulfuric acid:

SO3 + H2O = H2SO4

Note: O(1P) + O2 (or N2) --> O(3P) + O2 (or N2 or more generally, a second body M)

Source: See Eq 4 at http://olab.physics.sjtu.edu.cn/papers/2017/29.Huan%20Yue_PC... , where apparently, O(3P) is created from severe collision quenching of O(1D) atom with air or oxygen and acts as the major oxidant in the work by Huan Yue and colleagues ‘Exploring the working mechanism of graphene patterning by magnetic-assisted UV ozonation’. Note, O(3P) is also known as highly reactive ground-state 3P oxygen and a form of atomic oxygen.

Here is a link to a manual created by NASA relating to how atomic oxygen was attacking spacecraft surfaces, link: https://standards.nasa.gov/file/489/download?token=9HubpXP6 .

[Edited on 2-6-2018 by AJKOER]

AJKOER - 4-6-2018 at 08:22

I just found a good source reference (especially for 1977) of sulfur based reactions relating to the atmosphere, some leading to H2SO4 or SO3, in 'Sulfur in the Atmosphere: Proceedings of the International Symposium Held in Dubrovnik ...', Table 5, page 209, at https://books.google.com/books?id=EvsbBQAAQBAJ&pg=PA209&... and associated discussions on prior pages.

Upon reviewing the reference, a proven method to SO3 (and also H2SO4) comes to mind from SO2 and O2, with the introduction of a catalytic amount of NO2. It can be simply described with a two reaction cycle, including equation (27):

NO2 + SO2 = NO + SO3 (27)

And:

NO + 1/2 O2 --> NO2

For a net reaction of:

SO2 + 1/2 O2 --NO/NO2--> SO3

Per the reference's reactions (28) and (29), other NxOy can also be involved. Per other sources, a related system proceeds in the presence of H2O.

The process is akin to a well known method to sulfuric acid which I will let others discuss (reference, see for example, 'Development of the Catalytic Chamber Process for the Production of Sulfuric and Nitric acids from Waste Flue Gases', in particular, page 7, at https://nepis.epa.gov/Exe/ZyNET.exe/91002JK9.txt?ZyActionD=Z... and, at SM, http://www.sciencemadness.org/talk/viewthread.php?tid=2824 ).
-------------------------------------

Some theoretically interesting (and unconventional) ways to possibly obtain small quantities of NO2/NO absence HNO3 or H2SO4, but with a nitrate salt, from say stump remover (KNO3). Treat solid KNO3 with a spray of H2O with dissolved N2O (sold in stores, like Walmart, as a drink flavor enhancer in gas cartridges) in ocean/beach/snow UV augmented sunlight in the presence of SO2. Theoretical reactions:

N2O + H2O + uv --> N2 + .OH + OH-

NO3- + .OH = .NO3 + OH- (see http://adsabs.harvard.edu/abs/2001JGR...106.4995P )

.NO3 + SO2 = NO2 + SO3 [Eq (28) per source above]

An alternate path involving singlet oxygen formation in the presence of N2O and a UV lamp:

N2O (dry) + hv --> N2 + O(1P) (see p. 15 at http://cires1.colorado.edu/jimenez/AtmChem/CHEM-5151_S05_L7.... )

N2O (dry) + O(1P) --> 2 NO (p. 15 also)

which is a nitrate free path.

Note, UV photolysis of dry N2O, SO2 and O2 would be a combined method approach. Adding heat to the UV photolysis may assist the Lead Chamber's NO2 catalytic approach which is slower at normal temperatures.
-------------------------------------------------------------------

Note, per the first method I presented in this thread, avoid over production of singlet oxygen, which can act on oxygen forming O(3P), due to reaction (46) discussed on page 219 destroying SO3, which could reduce yield:

O(1P) + O2 --> O(3P)

O(3P) + SO3 (+ M) --> SO2 + O2 (+ M) (46)

I would introduce O(1P) gradually into an excess of (SO2+O2) to limit lose of SO3 yield.

[Edited on 5-6-2018 by AJKOER]

[Edited on 5-6-2018 by AJKOER]