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hissingnoise
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OK, lets try again, your wording is ambiguous and very confusing, but SO2 from bisulphate decomp. is oxidised by V2O5
@ ~500°C and the produced VO2 is oxidised in air, regenerating the catalyst . . .
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violet sin
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ya sure is. what I was saying was I was researching certain aspects of the reaction. I have much to buy for this to build a proof of concept. one of
the main issues is the need for high quality SO2. if you use a sulfur candle with air you have to scrub the gas of ash, H2O, etc. so to get better
SO2 that doesn't need scrubbing you can go with a sulfur burner that is fed with only O2 or you can make it with a chemical rxn. one way of doing
that is to use the Na/K metabisulfite heating it to decomp. hence the previous wiki equation. this leaves Na2O and makes SO2 only(supposedly). so
you get your gas that shouldn't need to be scrubbed and when you wash out your glass (carefully) H2O + Na2O --> 2NaOH,,, free lye. seeing as how I
don't have a fume hood and ground glass I havn't been able to try the decomp and see how it proceeds. which is important, as you feed in the SO2 and
O2 to the cat, it should be in proper proportions. too little O2 and it may not sustain temp for the catalyst. wasting materials and time. but the
reaction is exothermic and if it came over too fast you have mix issues and/or it could overheat your catalyst. push too much heat would make the
cooling inefficient. with out time for the mix to cool down the repeated passes through the cat bed are wasted. so you are wasting resources for
nothing again. gotta balance incoming reagents to manage heat to effect cooling to maintain any sense of effiency. if your gonna build it from the
ground up and deal with all the nasty chems you might as well do it good no? other wise it is just a big waste of time.
*forgot, reading suggested complexing the V2O5 with ammonia to make an ammonium metavanadate solution. this is mixed with a few % of K2SO4 and doused
on the catalyst support. it's then heated to drive off the ammonia and there you have your evenly distributed catalyst. I hope to go with 0.5~0.75
inch ceramic bead grow medium from the gardenshop in a stainless tube(s) there is a LOT of info on this site about this subject and I have read
quite a lot. no need to go down a bunch of dead ends when you can learn from others.
[Edited on 25-1-2013 by violet sin]
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hissingnoise
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It's so much easier buying your H2SO4, unless, of course. you want oleum . . .
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violet sin
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ya it absolutely is cheaper all the way around to buy H2SO4. but I like a challenge, and I am not saying I will succeed but I am sure gonna give it a
try. when ever I can cobble something together in my spare time i'll work on it. also would it not kick ass to be able to say you build a small acid
plant?! make a couple gallons once a year would be fine by me.
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hissingnoise
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| Quote: | | . . . but I like a challenge . . . |
Well, it certainly is challenging ─ if you do produce SO3 you'll need conc. H2SO4 as absorbent because
the trioxide will not dissolve in water, producing instead, a practically incondensible corrosively acid mist!
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Adas
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Quote: Originally posted by hissingnoise  | | Quote: | | . . . but I like a challenge . . . |
Well, it certainly is challenging ─ if you do produce SO3 you'll need conc. H2SO4 as absorbent because
the trioxide will not dissolve in water, producing instead, a practically incondensible corrosively acid mist!
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Or instead, condense the SO3 and put a little piece of ice. This reaction would not be so exothermic. You can then dilute it with more ice.
Btw, if this is true, how did they make the first H2SO4? 
Rest In Pieces!
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White Yeti
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Making sulfuric acid by this method is rather insensible, however, if you're after SO3/oleum, this is definitely worth a shot if you're willing to
risk life and lung to do it.
If you want to make sulfuric acid just for a challenge, there are other, more challenging, yet safer things to try. I would argue that making
hydrazine is much safer than pulling this off. If you read the prepublications section, you'll see that SO3 can manage to pass through a cooled
u-tube, and a condenser all the way to a polyethylene tube and react with it.
http://www.sciencemadness.org/talk/viewthread.php?tid=10332
The tube shows you how your fume hood would look like after this endeavour if you omitted it (provided that you use a fume hood) and it shows you what
your lungs would look like of you didn't bother using a fume hood. Of course, you'd be dead after the first few whiffs.
I'm an asthmatic, the thought of SO2 already sends shivers down my spine, but as for SO3, that's where mad science ends and insanity begins.
"Ja, Kalzium, das ist alles!" -Otto Loewi
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hissingnoise
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| Quote: | | Btw, if this is true, how did they make the first H2SO4?
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Oh, come on?
And before fucking around with SO3 it's well to read up on this compound's forms and its odd little dangerous trick . . .
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Adas
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| Quote: Originally posted by hissingnoise | | Quote: | | Btw, if this is true, how did they make the first H2SO4?
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Oh, come on?
And before fucking around with SO3 it's well to read up on this compound's forms and its odd little dangerous trick . . .
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Yeah, I know about "alpha explosion" - if that's what you meant 
Rest In Pieces!
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hissingnoise
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I had to check, just in case . . .
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Adas
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I have got just the basic equipment so there is no way of making SO3 for me.
Rest In Pieces!
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hissingnoise
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. . . same boat . . .
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violet sin
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my envisioned version would be mainly durable s.s tubing, a tube furnace w/ *at least* 2 heat zones for multiple passes. the idea being more of a
bundle of smaller tubes in one tube furnace with a gradient ~450-650'C. the length and position of the tubes in the parallel stack would define the
zones for the repeated passes. that way if I got it right on one pass, I could start stacking more tubes for multiple passes for increased
efficiency, providing the cooling could keep up of course. I don't wanna visit the alpha explosion either, even in an all metal construction it would
be disastrous to say the least.
huge considerations are SO3 reacting w/ cooling media if it eats through = boom. alpha explosion or blockage from over effective cooling = boom. poor
s.s heat conduction for cooling, SO2 leaks, vanadium toxicity, hot or even boiling H2SO4, oleum, storage of product, cost of machine, etc, etc, etc.
the list of hurdles is HUGE to say the least. and that is just to get it working. clean up after a run would be the bitch as far as I can see.
but with a well thought out plan with room for flexibility, it could be possible to not kill your self and produce. hand making a large portion of
the machine would be fun and rewarding. shouldn't be to hard to make a hand wound nichrome tube furnace in a 4 foot section of 8"terracotta chimney
insert and kao wool insulation. wrap it with a healthy coating of carpenters cloth on the exterior to prevent fragmentation in the case of an
explosion. only one small link in the chain though. maybe I will finish by next winter. maybe not. working away from home leaves much time to plan
and little to act sadly. though there is much to be had/salvaged for free or cheap if you know where to look.
I would do this out side of course, no freaking in home fume hood considerations what so ever... laugh if you will, it does sound insane I know.
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macckone
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How was Sulfuric acid first made.
By creating sulfur trioxide from ferrous sulfate and dissolving it in
water in VERY small quantities. If the amount of water is large
enough and the amount of gas small enough you get very dilute
sulfuric acid. This can then be concentrated. Then the
concentrated acid can be used to gather larger quantities of
trioxide.
The second method was the chamber process which doesn't
generate the aerosol in the same manner so it condenses eaiser.
A number of people have good success distilling sulfuric acid.
This also results in a sulfuric acid gas. The aerosol should
actually be somewhat easier to deal with but you need a packed
column for the aerosol to accumulate on.
The bigger problem is the large amount of gas in the
intermediate step with the trioxide. You can't do this in a
sealed system efficiently unless the trioxide is combined
with steam and even then you have a significant expansion
factor. BTW, the lead chamber process usually used steam
input to combine with the dioxide as well as regulate the temp.
One catalyst substrate that is ideal that hasn't been mentionend
is perlite. It has a very large surface area. It contains several
percent of sodium and potassium. And the melting point is
sufficiently above the reaction temperature to not be a problem.
The primary concerns would be contaminants that could poison
the vanadium catalyst and absorption of water which could be
difficult to drive off before use.
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