Sciencemadness Discussion Board - sulfuric and hydrochloric acid generator design

sulfuric and hydrochloric acid generator design

420MLGnOhEADsCOPEpro - 23-1-2015 at 15:32

i plan to set up a system as such

electrolyse NaCl
http://en.wikipedia.org/wiki/Downs_cell
i have a kiln which can easily achieve the required temperature
the downs cell itself will be constructed with clay and the chlorine will be vented out of the kiln through borosilicate pipes
after the chlorine exits the kiln it may be cooled and transitioned to plastic pipe

sulfur dioxide is generated by simply burning sulfur
the sulfur dioxide is cooled in metal pipe then transitioned to plastic pipe

sulfur dioxide and chlorine gas are mixed 1:1 and forced through an activated carbon catylist where it reacts into sulfuryl chloride
http://en.wikipedia.org/wiki/Sulfuryl_chloride

sulfuryl chloride is bubbled through water where it reacts into hydrogen chloride and sulfuric acid

is there anything i've overlooked that may cause a problem or anything that might simplify the system or otherwise make it work better

Molecular Manipulations - 23-1-2015 at 16:39

You remind me of myself, a couple years back.
It's really easy to do somthing like this, on paper, but when you actually start building it, you realize how much more difficult it is.
I get that you're trying to make/isolate all three chemicals (sodium, sulfuric and hydrochloric acid) but which do you want more? There's easier ways to get all three of these chemicals than the methods proposed here, separately.
In theory it might work, but never without a strong, quality setup, pressure gauges, flow meter, regulators and a lot more thought and several hundred dollars at least. It just won't be practical.

420MLGnOhEADsCOPEpro - 23-1-2015 at 16:52

Quote: Originally posted by Molecular Manipulations

It's really easy to do somthing like this, on paper, but when you actually start building it, you realize how much more difficult it is.

that's exactly why i came here
if anybody has done something similar they probably at least have some idea of how to make the project go more smoothly

i'd like to buy the chemicals i need but i don't need enough to buy in bulk and otherwise they would cost hundreds or thousands of dollars

i have lots of free time and most of the materials i need so i figure it's reasonable to build something

j_sum1 - 23-1-2015 at 22:20

Keep it simple.
I would go for one product at a time. It is so easy to run into hurdles and you end up spending more time and money than you would if you simply purchased the stuff. And you are likely to end up with low yield and/or low purity.
Multiply this by three for the triple system you are devising.

One thing to consider with your design is that if it does not work then you are missing tree products. On the other hand, if you have three separate processes then one can fail and you are still producing the other two.

smaerd - 24-1-2015 at 12:56

I think it's a cool idea. However, in order to do this you would essentially be setting up a miniature industrial manufacturing process to produce two very common and widely available chemicals and sodium metal. Thinking about the costs of doing this "properly" makes my wallet shrivel considering I go through a liter of either acid maybe every year. More power to you, have you started any more concrete plans for the design yet? Edit- I can definitely see safety and fail-safes being important here. Those gasses are not friendly and are a serious concern on the mole+ scale.

The reactions look pretty standard so the chemistry is there, the 'engineering' is what comes next. Other-wise there isn't much to talk about.

[Edited on 24-1-2015 by smaerd]

420MLGnOhEADsCOPEpro - 24-1-2015 at 20:37

Quote: Originally posted by j_sum1

Keep it simple.
I would go for one product at a time. It is so easy to run into hurdles and you end up spending more time and money than you would if you simply purchased the stuff. And you are likely to end up with low yield and/or low purity.

i'll definitely test the systems one at a time before putting them together and i'm sure it will require quite some adjusting to get them running together
(between making the sulfur burn at a somewhat steady rate and finding the right amperage for the electrolysis) but i've got lots of free time anyway

420MLGnOhEADsCOPEpro - 24-1-2015 at 20:49

Quote: Originally posted by smaerd

I can definitely see safety and fail-safes being important here. Those gasses are not friendly and are a serious concern on the mole+ scale.

i'm thinking the following safety precautions are in order
>naturally safety goggles
>cloth wet with aqueous sodium bicarbonate to breath through (will react with gas before it gets to your lungs)
>wet ph tests all over the pipes (will change color if small concentrations of gas escape)
>a bucket of water (in the event the sulfur needs to stop burning)
>multiple places the electrolysis circuit can be broken (to prevent running wildly across the garage)
>testing all pipes for leaks (by means of bicycle pump)

Oscilllator - 24-1-2015 at 21:57

I'm afraid one does not "simply burn sulfur." Taking a good long look through this thread will show that a sulfur burner is not an easy undertaking. The member axehandle tried many methods, each more crackpot than the last, and I don't believe he ever succeeded.

420MLGnOhEADsCOPEpro - 25-1-2015 at 14:11

Quote: Originally posted by Oscilllator

I'm afraid one does not "simply burn sulfur." Taking a good long look through this thread will show that a sulfur burner is not an easy undertaking. The member axehandle tried many methods, each more crackpot than the last, and I don't believe he ever succeeded.

i had considered this might be difficult (though because i have no way to put enough air into a burning chamber not because sulfur burns poorly) and have found a solution
http://en.wikipedia.org/wiki/Sodium_chlorate
i can make oxidizer from sodium hydroxide and chlorine
thus allowing the design shown

>sulfur is slowly dripped into the salt
>sulfur reacts with NaCl / NaClO3 mix (the chlorate is diluted to prevent explosive burning and reduce gaseous sulfur (the top layer of NaCl is to trap the rest of the gaseous sulfur))
>SO2 escapes through the output with some amount of pressure behind it (important for forcing it through the catylist)

Molecular Manipulations - 27-1-2015 at 09:18

I've gotten a sulfur burner to work with only sulfur and oxygen.
I bubbled oxygen through liquid sulfur and lit the top with a torch.

Not sure if it would work with air though. Why not try SO₂ oxidation with O₂ and V₂O₅ catalyst?

[Edited on 27-1-2015 by Molecular Manipulations]

Loptr - 27-1-2015 at 10:18

I hope you have the elbow room for this undertaking. I can't imagine this would be very friendly for a residential area.

Fulmen - 27-1-2015 at 10:32

Quote: Originally posted by Oscilllator

I'm afraid one does not "simply burn sulfur."

There is always something, isn't it? I've looked at most routes, but the only one that appeals to me is the contact process. Reading up it seems like the V2O5-route is quite doable with the equipment I have available, and it all stops because you can't get sulfur to burn in air? Jeeez, is somebody doing this on purpose?

Metacelsus - 27-1-2015 at 14:10

When I was working in a university lab, the grad students were doing some reactions using sulfuryl chloride (converting disulfides to sulfenyl chlorides). Saying that stuff is nasty is putting it mildly. I'd call it face-melting.

420MLGnOhEADsCOPEpro - 27-1-2015 at 14:39

Quote: Originally posted by Molecular Manipulations

I've gotten a sulfur burner to work with only sulfur and oxygen.
I bubbled oxygen through liquid sulfur and lit the top with a torch.

i considered something of the sort (though with air instead of O2) but it think the flame might go out to easily because i don't intend to run this thing particularly fast

@Loptr i have almost 5 acres or 20234.3 sq meters (142.25 meters square)

420MLGnOhEADsCOPEpro - 27-1-2015 at 14:49

Quote: Originally posted by Cheddite Cheese

When I was working in a university lab, the grad students were doing some reactions using sulfuryl chloride (converting disulfides to sulfenyl chlorides). Saying that stuff is nasty is putting it mildly. I'd call it face-melting.

it's only a bit more than twice as bad as SO3

i'll put the SO2Cl2 part in the bubbler (vvv like this) so it should be the safest part

Molecular Manipulations - 27-1-2015 at 14:53

Melt the sulfur first, pour it in the burner, then turn on the air pump/oxygen cylinder and direct a torch flame to the sulfur. Always worked for me.
I then bubble the sulfur dioxide through water, through an ionizer to get rid of smoke particles and then through a calcium chloride tube to dry it.
I once used a few grams of vanadium pentoxide and tried out the Contact Process. It's not too hard but next time I'll buy the ready made catalysts.

420MLGnOhEADsCOPEpro - 27-1-2015 at 14:57

Quote: Originally posted by Molecular Manipulations

Melt the sulfur first, pour it in the burner, then turn on the air pump/oxygen cylinder and direct a torch flame to the sulfur. Always worked for me.
I then bubble the sulfur dioxide through water, through an ionizer to get rid of smoke particles and then through a calcium chloride tube to dry it.
I once used a few grams of vanadium pentoxide and tried out the Contact Process. It's not too hard but next time I'll buy the ready made catalysts.

if i were going to do the contact process i'd make a vanadium aero gel
http://www.aerogel.org/

Loptr - 27-1-2015 at 16:15

Quote: Originally posted by 420MLGnOhEADsCOPEpro

Quote: Originally posted by Molecular Manipulations

I've gotten a sulfur burner to work with only sulfur and oxygen.
I bubbled oxygen through liquid sulfur and lit the top with a torch.

I am familiar with acres.

I was just trying to make sure that this wasn't being done in an apartment or a crowded neighborhood. It seems you do have some privacy. I was just thinking "what-if" in the event something went awry.

Fulmen - 28-1-2015 at 08:13

Quote: Originally posted by Molecular Manipulations

next time I'll buy the ready made catalysts.

Where would you get smaller amounts of this? And how much difference in efficiency and life span would you expect? Or is it simply due to cost and effort?

chief3 - 28-1-2015 at 09:18

Why dont you just try the following:

==> Step 1 : Get yourself some sulfate ... , eletrolyze it with a diaphragma ... : Redy there is some diluted H2SO4 ... ; this can be concentrated by heat ... although some salt will remain in the concentrated resudual ; distillation of the concentrate might be possible to get quite clean H2SO4 ...
==> Step 2: React the H2SO4 with NaCl ... , to have HCl - vapors ; those can be reacted with water to form HCl-acid .

Molecular Manipulations - 28-1-2015 at 11:27

There's some at Alibaba. Most have a large minimum order, but a few are OK.
I don't think you can use pure vanadium pentoxide as a catalyst, it needs to be mixed with several other compounds, including cesium oxide and other exotic chemicals. Buying it is much easier than making it.

Fulmen - 28-1-2015 at 11:44

Nice, didn't even think of looking there. As for making catalysts, several people here has done it with apparently good results. Doesn't require more than some ammonia and K2SO4 plus a substrate, but I agree that buying would be even simpler.

420MLGnOhEADsCOPEpro - 28-1-2015 at 12:19

Quote: Originally posted by chief3

Why dont you just try the following:

==> Step 1 : Get yourself some sulfate ... , eletrolyze it with a diaphragma ... : Redy there is some diluted H2SO4 ... ; this can be concentrated by heat ... although some salt will remain in the concentrated resudual ; distillation of the concentrate might be possible to get quite clean H2SO4 ...
==> Step 2: React the H2SO4 with NaCl ... , to have HCl - vapors ; those can be reacted with water to form HCl-acid .

i have other projects that require chlorine gas and sodium metal is handy for some things too
also diaphragms

Molecular Manipulations - 19-2-2015 at 21:09

Any progress yet 420pro? What material are you planning on using for pipes and tubes?

420MLGnOhEADsCOPEpro - 20-2-2015 at 18:54

Quote: Originally posted by Molecular Manipulations

Any progress yet 420pro? What material are you planning on using for pipes and tubes?

after the gas is put through a heat exchange all the pipe will be pvc for convenience
before the heat exchange though i'm going to electroplate the inside of a piece of conduit in nickel which should then react into NiCl which is chlorine resistant and solid up to 1000 C
if that doesn't work i'll use borosilicate pipe though borosilicate is more expensive, requires a larger heat exchanger, and is less easily coupled to pvc (due to the difference in available diameter)

as for the sulfur burning part the high temperature pipes are aluminum and the rest are again pvc

recently i've been a bit side tracked with an aerogel project though both projects require chlorine gas so they should come together around he same time
i'll be done with this and post results in 2-12 weeks

kjpmi - 22-2-2015 at 20:52

Quote: Originally posted by 420MLGnOhEADsCOPEpro

i'd like to buy the chemicals i need but i don't need enough to buy in bulk and otherwise they would cost hundreds or thousands of dollars

i have lots of free time and most of the materials i need so i figure it's reasonable to build something

I'm going to play devil's advocate here...

When you say the chemicals you need costing hundreds or thousands of dollars, are you refering to the end products? HCl and H2SO4? Because you can buy each thru many chem supply places online for like $20 to $30 per liter for each. Why would you ever build something like this for end products that are so cheap?

OR are you refering to the chemicals you need beforehand (Sulfur, Cl gas, etc.)? Everything you need can be found for relatively cheap if you look. Unless you live in some odd country where they WOULD cost thousands. In that case why not just buy the much more available HCl and H2SO4???? It would still be cheaper than the precursors.

I understand the fun of making some of the chemicals you need yourself. There are certain things I could easily buy but I preferred doing the chemistry myself just for the sheer experience.
Then again, I'll just never understand why people go thru quite elaborate, expensive, and convoluted processes only to get shitty yields and product of questionable quality for some of THE cheapest, most readily available, high grade, already anydrous, etc. chemicals.

Spend the money on glassware or other equipment for the real reactions and syntheses you intend to do, not hundreds or thousands of dollars on HCl and H2SO4.
Or spend it on other less common chemicals, stock up on a nice diverse lab and try some other obscure, less well known, but really fun and interesting syntheses.

420MLGnOhEADsCOPEpro - 22-2-2015 at 21:56

Quote: Originally posted by kjpmi

When you say the chemicals you need costing hundreds or thousands of dollars, are you refering to the end products? HCl and H2SO4? Because you can buy each thru many chem supply places online for like $20 to $30 per liter for each. Why would you ever build something like this for end products that are so cheap?

i don't think you understand
$20/L * 50L = $1000
a 55gal drum full of conc H2SO4 isn't out of the question

Molecular Manipulations - 22-2-2015 at 22:04

First $20-30 a liter is WAY more than I would pay for hydrochloric or sulfuric acid. I get sulfuric for about $8 a liter when I buy three at a time, and hydrochloric is like $6 a gallon at a hardware store.
Anyway the profit margin is huge if you can make sulfuric acid from sulfur, air and water.
You can get sulfur for about $60 for 32 Kg on Alibaba, which is 1000 moles, which in turn can make 1000 moles of sulfuric acid, or about 98 Kg.
If you can sell 98 Kg of sulfuric acid you could easily get $300 if you're practically giving it away. $10.00 a liter and you've turned that $60.00 into $450.00.
It's not at all a bad idea to try to sell it if you can 420pro, or do you actually want to use it all yourself?

[Edited on 23-2-2015 by Molecular Manipulations]

j_sum1 - 22-2-2015 at 22:20

Quote: Originally posted by 420MLGnOhEADsCOPEpro

a 55gal drum full of conc H2SO4 isn't out of the question

It is for me!

In any case you need a proof of concept on a much smaller scale before you build a working prototype before you scale up to industrial volumes. And at that point the hundreds or thousands of dollars is more a question for your financial backers and your sales pitch.

420MLGnOhEADsCOPEpro - 24-2-2015 at 20:47

Quote: Originally posted by j_sum1

In any case you need a proof of concept on a much smaller scale before you build a working prototype before you scale up to industrial volumes. And at that point the hundreds or thousands of dollars is more a question for your financial backers and your sales pitch.

this project is not for industrial production as it is definitely more expensive on any scale than SO3 production
the purpose of the project is a stable relatively low cost source of acids that isn't a minimum order of 5 tons

420MLGnOhEADsCOPEpro - 24-2-2015 at 21:25

Quote: Originally posted by Molecular Manipulations

or do you actually want to use it all yourself?

selling strong acids requires some level of paperwork as far as i'm aware (for safe shipping i think) and also there's income tax if it's more than some amount of profit made so i'd prefer to stick to just using it myself
on top of that there are cheaper ways i could make sulfuric acid if i had a larger demand such as
(MgSO4 @ 1124C -> MgO + SO3) if you get 25 tons MgSO4 is about $0.05/Kg and the energy costs ~ $0.02-0.05/Kg = less than $0.13/Kg of H2SO4
and that's not even considering the price of the resulting MgO which i've seen as low as $0.11/Kg so selling for $0.1/Kg that's an extra $0.04/Kg of H2SO4 in MgO bringing the total to $0.09/Kg of H2SO4 after slightly estimating high (realistic estimate being ~ $0.065/Kg)
it's realistic to sell H2SO4 at >$0.15/Kg bringing profit to >$0.06/Kg of H2SO4 (or realistically >$0.095/Kg, how much greater than depending on what it sells for)
i may do this at some point considering my current research is high temperature aerogels but any noteworthy production would cost at least $2,000 to get started likely more than $10,000

Molecular Manipulations - 26-2-2015 at 09:08

I wouldn't use PVC for sulfuryl chloride. According to this material resistance chart, sulfuryl chloride is incompatible with PVC. I'd use glass for that. 98% sulfuric acid is also not very stable with the same.

[Edited on 26-2-2015 by Molecular Manipulations]

420MLGnOhEADsCOPEpro - 26-2-2015 at 19:40

Quote: Originally posted by Molecular Manipulations

I wouldn't use PVC for sulfuryl chloride. According to this material resistance chart, sulfuryl chloride is incompatible with PVC. I'd use glass for that. 98% sulfuric acid is also not very stable with the same.

this link doesn't work but a quick google search agrees
i'll just use conduit though because glass pipes are expensive
the pipes shall be soldered with copper (because high temp) for all connections (because conduit doesn't require connectors and costs about the same it may actually be cheaper than pvc)

results part 1

420MLGnOhEADsCOPEpro - 18-5-2015 at 18:46

a working apparatus has been made however it strays from the original design

the original downs cell was entirely scrapped after it was found that high temperature gas tight seals are difficult to make without good materials
a membrane cell was then attempted using a piece of paper as the membrane
it was found that the membrane was unnecessary and that HCl worked better than NaCl as a chlorine source

the sulfur burning apparatus was also scrapped as it would require high temperature seals and an alternative was found
sulfur and chlorine react into sulfur dichlroide and disulfur dichlride at room temperature following these equations
S8 + 4Cl2 -> S2Cl2
S8 + 8Cl2 -> SCl2
S2Cl2 + 4Cl2 -> SCl2
this also means that the carbon catalyst is obsolete as the resulting SCl2 and S2Cl2 react with water according to these equations
16SCl2 + 16H2O -> 32HCl + 8SO2 + S8
16S2Cl2 + 16 H2O -> 32HCl + 8SO2 + 3S8
in solution SO2 becomes H2SO3 which reacts with hypochlorous acid according to this equation
H2SO3 + HClO -> H2SO4 + HCl

to test this an apparatus was built as such
an old mayonnaise jar was used as the container for the solution
fuming HCl was added to the container
sulfur powder was added to the container
the container was stirred as to distribute the sulfur
a piece of pencil lead and a piece of iron were used as the positive and negative electrodes respectively
a 5 volt DC power supply was acquired
it should be noted that the voltage was not measured but was produced by a phone charger which claims to produce 5 volts

the apparatus was powered for ~6 hours after which the solution had turned red
during the ~6 hours it was observed that the nearby air smelled strongly of chlorine and that the apparatus was fuming the entire time (which hurt my nose

)

the red color of the solution is proof that H2SO4 and an oxidiser were produced
tomorrow i will acquire anther piece of pencil lead to replace the iron electrode which will prevent the H2SO4 from being consumed (unless it rains all day)
i will also take some pictures

complete sulfuric apparatus 1.png - 40kB

420MLGnOhEADsCOPEpro - 18-5-2015 at 22:14

i forgot to mention that the method i used will not work with NaCl instead of HCl
if you use NaCl the Na will form NaOH which will then react with the sulfur into polysulfides and thiosulfides and possibly other things thus not getting you sulfuric acid or hydrochloric acid
luckily this is easily avoided by electrolysing the NaCl in a separate container and then venting the chlorine to the sulfur and water mix
it may be beneficial to have the sulfur and water in different containers as well (at the very least the end product doesn't have to be filtered) though this can cause problems

results part 2 (pics)

420MLGnOhEADsCOPEpro - 19-5-2015 at 17:54

today i acquired another carbon electrode and began another test
i could not produce enough sulfuric acid to make a copper sulfate solution because i had the apparatus set up wrong for most of today but i should have some tomorrow
anyways here are the pictures i took today

1st pic is the iron electrode that was used
yesterday it was green from the chlorine but somehow it rusted overnight

2nd pic is yesterdays solution with the sulfur filtered out
it was red orange before i filtered it and when i began filtering it
i used extra water to get more of the salt through the filter but upon diluting it became yellow (is this from ph change)
i would have taken a picture before if i knew this would happen
i'm currently letting some dry out in a dish but it's rather humid today

3rd pic is residue from some of the solution i spilled
when spilled it reacted with the concrete because there's still a notable concentration of acid in it
the red color is definitely the same that i saw in solution before it was diluted

4th pic is the apparatus running the second batch

5th pic is inside the apparatus while it's running
the contents of the jar are yellow from the sulfur dust
the middle of the jar is lighter because there is sulfur on the surface there whereas the rest of the sulfur has sunk (i found that the entire surface of the water should be covered in sulfur for the apparatus to work efficiently after i noted there was very little sulfuric acid in solution and lots of escaping chlorine)
the dark rod in the bottom of the container is an electrode that fell in during setup
the dark ball in the bottom of the container is a wad of copper wire that i used as a test for sulfuric acid (as sulfuric acid reacts with copper to make blue copper sulfate and hydrochloric acid does not react with copper(chlorine reacts as well but it makes green copper chloride and that reacts with sulfuric acid into copper sulfate as well))

so there you have it
there should be a few more pictures tomorrow too

11113761_664993806967641_5801468697086431751_n.jpg - 112kB

11212781_664993823634306_5881930467386119810_n.jpg - 93kB

11227400_664993813634307_2700865997574366824_n.jpg - 139kB

11231912_664993836967638_2365632950568909904_n.jpg - 81kB

11234918_664993833634305_6634908779775955070_n.jpg - 100kB