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hissingnoise
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| Quote: | | As for the wires, they are very thin; .005 inch diameter. . |
-Melgar, at .005" the surface area will be so small you'd need a very long wire to ensure a working surface-area big enough to produce usable
quantities of NO.
You might as well face it - you're grasping at straws. . .
-Chief, I've seen 96%H2SO4 D/C on eBay UK - eBay Deutschland might have it too.
[Edited on 1-3-2010 by hissingnoise]
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watson.fawkes
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Quote: Originally posted by hissingnoise  | | at .005" the surface area will be so small you'd need a very long wire to ensure a working surface-area big enough to produce usable quantities of NO.
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I must agree; that surface area is mighty small. There are only two catalysts used in industry for catalytic
oxidation of ammonia for nitric acid production: platinum and cobalt oxide. I did a review of patent literature last year on the subject, and most of
it was about how to conserve and/or recover the platinum catalyst. Another good piece of it was how to increase surface area. My suggestion is to
figure out how to use cobalt oxide on a small scale. It likely means a tube furnace with good temperature control and a packed-column catalyst bed.
The desired reaction only happens within a certain temperature range, and you've got both external heating and an exothermic reaction to manage.
Ceramic beads are used as catalyst supports ordinarily. Some creativity about how to make this (with smaller dimensions) or an equivalent would be a
real contribution.
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Melgar
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| Quote: Originally posted by watson.fawkes | | Quote: Originally posted by hissingnoise | | at .005" the surface area will be so small you'd need a very long wire to ensure a working surface-area big enough to produce usable quantities of NO.
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I must agree; that surface area is mighty small. There are only two catalysts used in industry for catalytic
oxidation of ammonia for nitric acid production: platinum and cobalt oxide. I did a review of patent literature last year on the subject, and most of
it was about how to conserve and/or recover the platinum catalyst. Another good piece of it was how to increase surface area. My suggestion is to
figure out how to use cobalt oxide on a small scale. It likely means a tube furnace with good temperature control and a packed-column catalyst bed.
The desired reaction only happens within a certain temperature range, and you've got both external heating and an exothermic reaction to manage.
Ceramic beads are used as catalyst supports ordinarily. Some creativity about how to make this (with smaller dimensions) or an equivalent would be a
real contribution. |
Thank you very much for the suggestion. Unfortunately, it appears sulfur has a tendency to poison cobalt oxide catalysts. Looks like it's back to
platinum then, although this time I'll try electroplating it onto titanium wire to increase the surface area. That should work, right?
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hissingnoise
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Attaboy! With determination like yours, everything's possible!
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watson.fawkes
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| Quote: Originally posted by Melgar | | Thank you very much for the suggestion. Unfortunately, it appears sulfur has a tendency to poison cobalt oxide catalysts. |
So take the sulfur out. Use a phosphate-ammonium fertilizer. Or better yet, if you're after nitric acid, just by a tank of liquid
ammonia at said fertilizer store. | Quote: | | Looks like it's back to platinum then, although this time I'll try electroplating it onto titanium wire to increase the surface area. That should
work, right? |
If you can get a reliable method of doing that, please do publish how.
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Melgar
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| Quote: Originally posted by watson.fawkes | | Quote: Originally posted by Melgar | | Thank you very much for the suggestion. Unfortunately, it appears sulfur has a tendency to poison cobalt oxide catalysts. |
So take the sulfur out. Use a phosphate-ammonium fertilizer. Or better yet, if you're after nitric acid, just by a tank of liquid
ammonia at said fertilizer store. |
Yesterday I found out that my local hydroponics store actually has bags of unblended fertilizer that they use to make their own blends for customers,
they just don't normally offer it like that for sale. Anyway, I got a pound of calcium nitrate fertilizer, then mixed it with H2SO4 drain opener and
distilled the result, giving me 200 mL or so of fuming white nitric acid.
So, I'm not quite as interested in the ammonium sulfate route to nitric acid anymore, although it would still be helpful to have a means of turning a
sulfate salt into sulfuric acid. Can you actually get tanks of anhydrous ammonia at ag stores? I thought they put a stop to that because meth cooks
were using it.
| Quote: | | Quote: | | Looks like it's back to platinum then, although this time I'll try electroplating it onto titanium wire to increase the surface area. That should
work, right? |
If you can get a reliable method of doing that, please do publish how.
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Heh, I take it it's easier said than done? I'm assuming the first step is dissolving the platinum in aqua regia, but that's proving to be hard enough
by itself.
[Edited on 3/2/10 by Melgar]
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watson.fawkes
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| Quote: Originally posted by Melgar | | Can you actually get tanks of anhydrous ammonia at ag stores? I thought they put a stop to that because meth cooks were using it.
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Well, then don't be a meth cook. And don't look like one or act like one either.
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Melgar
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No, I mean, I think you have to prove you're a farmer to buy it now. But I don't think it's used by the farmers near where I live anyway. My dad's a
farmer, and he mostly gets urea or a blend, although he has gotten ammonium nitrate before. Ammonium sulfate was interesting to me because it's
really cheap due to it being an industrial byproduct, whereas the phosphates are fairly expensive. Plus, I need a better source of sulfuric acid that
doesn't have all that crap that's in the drain opener. Heating the ammonium bisulfate to drive off ammonia seems like it'd work, since presumably any
remaining sodium bisulfate would precipitate out at room temperature.
Also, I'm thinking of having a continuous stream of air blowing over the molten sodium bisulfate, through a condenser, then over the catalyst. The
air would then be bubbled through a solution of potash (potassium carbonate) where the NO2 would form nitric acid, then potassium nitrate. So
hopefully, that's three useful chemicals (NH3, KNO3, and H2SO4) from one not-so-useful one. Of course, I could always just use the ammonia for other
stuff if I didn't need any nitrate salts at the time.
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quicksilver
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C.A.N. 15.5-5-5 has generally replaced ammonium nitrate in packaged purchases. I live in a large farm area. AN generally is available by open truck
delivery to very few farmers who actually NEED AN. Berry and Tobacco benefit from straight AN bu "CAN" works for most all needs so that's what being
sold. One provider is able to get AN but no one wants it anymore. We even have some bagged C.A.N. now but some places are doing the "Be Aware for
America" thing from the Fertilizer Institute (YES - there is such a thing) and folks just don't like having their name on some list.
To have a delivery (generally) your purchase has to be in line with your planting acreage and coincide with time of year nitration (for most that Nov-
Feb) Then you have to have it stored in a special area! NO ONE puts up with that crap. So no one orders AN when "CAN" works just fine.
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hissingnoise
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The CAN I know quicksilver, is AN prills with a calcium carbonate coating.
The AN is easily separated from it but your CAN might be a different nitrate fertiliser.
If it's the same, then it makes Govt. restrictions laughable in their pointlessness.
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Melgar
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Yeah, I mean, you can just mix the aforementioned ammonium sulfate with calcium nitrate in water, and calcium sulfate will precipitate out, leaving
ammonium nitrate still dissolved.
Also, I found out that ozone will apparently oxidize ammonia pretty well. I have an ozone generator to get rid of the occasional bad smell, and I
turned it on in a room where i had spilled ammonia, and the room gradually filled up with a white, smoke-like mist. Set off the smoke detector too.
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not_important
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Note that calcium sulfate is slightly soluble in water, and that ammonium salts enhance the solubility; this has been documented many times before on
this board. For use in making HNO3 this solubility is likely not a problem, but it is if you are after NH4NO3 for other purposes.
The catalytic oxidation of ammonia is a delicate balance between low conversion rates and three competing reactions. The first is the cracking of NH3
to N2 and H2, the second is oxidation of NH3 to N2 and H2O, and the thirdis the reaction of nitrogen oxides with ammonia to give H2O and N2. That 3rd
is used to reduce NOx emissions in combustion exhaust, first NH3 is added to react with the nitrogen oxides and the the stream flows through a slip
catalyst where excess NH3 is oxidised to N2 and H2O.
Industrially this is made practical by using high surface area catalysts in thin layers with careful control of mix ratios, temperatures, flow rates,
and quick quenching. Not easy to do on a small scale at home, while a demonstration may produce traces of NOx it is going to give disappointing
yields.
The smoke you observed is in part ammonium nitrite - NH4NO2. When dissolved in water it tends to react with itself to produce N2 and H2O, reducing the
yields bassed on NH3 or O3 consumed.
Someone here once posted a description of a set-up that used copper, strong aqueous NH3, and air, to produced a solution of Cu(NO3)2 or the
corresponding tetra-ammonium complex.
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Melgar
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| Quote: Originally posted by not_important | Note that calcium sulfate is slightly soluble in water, and that ammonium salts enhance the solubility; this has been documented many times before on
this board. For use in making HNO3 this solubility is likely not a problem, but it is if you are after NH4NO3 for other purposes.
The catalytic oxidation of ammonia is a delicate balance between low conversion rates and three competing reactions. The first is the cracking of NH3
to N2 and H2, the second is oxidation of NH3 to N2 and H2O, and the thirdis the reaction of nitrogen oxides with ammonia to give H2O and N2. That 3rd
is used to reduce NOx emissions in combustion exhaust, first NH3 is added to react with the nitrogen oxides and the the stream flows through a slip
catalyst where excess NH3 is oxidised to N2 and H2O.
Industrially this is made practical by using high surface area catalysts in thin layers with careful control of mix ratios, temperatures, flow rates,
and quick quenching. Not easy to do on a small scale at home, while a demonstration may produce traces of NOx it is going to give disappointing
yields.
The smoke you observed is in part ammonium nitrite - NH4NO2. When dissolved in water it tends to react with itself to produce N2 and H2O, reducing the
yields bassed on NH3 or O3 consumed.
Someone here once posted a description of a set-up that used copper, strong aqueous NH3, and air, to produced a solution of Cu(NO3)2 or the
corresponding tetra-ammonium complex.
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I read some papers on the subject, and it's really not as delicate as you make it seem. For one, the first reaction, NH3 to N2 + H2 is practically
nonexistant, since it's not favored thermodynamically except maybe at really high temps. Kind of like how water doesn't tend to disassociate into
hydrogen and oxygen. As for the oxidation to water and nitrogen, that happens mainly above 1400C with platinum catalysts. That's a pretty wide
range, and keeping it in that range should be easy enough just by estimating the temperature due to color from black-body radiation.
Of course, you're right that getting the surface area high enough to convert most of the ammonia would be difficult. And now that I have a reliable
source of calcium nitrate, my incentive to get that working isn't as great. And it is good to know that oxidizing with ozone won't help me because of
the ammonium nitrite reaction.
As for purifying ammonium nitrate, couldn't it just be carefully heated to just over its melting point to get the calcium sulfate to precipitate out?
I know mixtures of salts usually have different melting points than the salts by themselves, but the huge difference in melting points should minimize
that effect, no?
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not_important
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| Quote: Originally posted by Melgar | ... For one, the first reaction, NH3 to N2 + H2 is practically nonexistant, since it's not favored thermodynamically except maybe at really high
temps. Kind of like how water doesn't tend to disassociate into hydrogen and oxygen...
...
As for purifying ammonium nitrate, couldn't it just be carefully heated to just over its melting point to get the calcium sulfate to precipitate out?
I know mixtures of salts usually have different melting points than the salts by themselves, but the huge difference in melting points should minimize
that effect, no? |
From S. Strelzoff's Technology & Manufacture of Ammonia
Percent NH3 in equilibrium with [N2+3H2] at 1 atmosphere pressure and various temperatures
T Cent. Percent NH3
350 0,838
400 0,405
450 0,214
500 0,1216
550 0,0736
600 0,0470
So even at 350C the equilibrium gives less than a percent NH3; catalysts simply speed up reaching equilibrium without changing the final ratios.
Increased pressure favours higher NH3 percentages, as would be expected; at 800 atmospheres and 500 C the equilibrium is 51% NH3 which demonstrates
why the H-B process is run at high pressures.
Melting ammonium nitrate is always a little dicey, especially if impure. Plus it's not straightforward to use solubility values for water as solvent
to solubility values in a non-aqueous solvent such as liquid ammonium nitrate. If all you are after is a route to nitric acid the amount of calcium
sulfate remaining in solution shouldn't be a problem. If you need pure NH4NO3 then using hot MeOH to dissolve the NH4NO3 is likely the best route
(solubility given in other threads); warm anhydrous NH3 under pressure works well as a solvent too, but is hardly a home lab method.
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Melgar
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| Quote: Originally posted by not_important | | Quote: Originally posted by Melgar | ... For one, the first reaction, NH3 to N2 + H2 is practically nonexistant, since it's not favored thermodynamically except maybe at really high
temps. Kind of like how water doesn't tend to disassociate into hydrogen and oxygen...
...
As for purifying ammonium nitrate, couldn't it just be carefully heated to just over its melting point to get the calcium sulfate to precipitate out?
I know mixtures of salts usually have different melting points than the salts by themselves, but the huge difference in melting points should minimize
that effect, no? |
From S. Strelzoff's Technology & Manufacture of Ammonia
Percent NH3 in equilibrium with [N2+3H2] at 1 atmosphere pressure and various temperatures
T Cent. Percent NH3
350 0,838
400 0,405
450 0,214
500 0,1216
550 0,0736
600 0,0470
So even at 350C the equilibrium gives less than a percent NH3; catalysts simply speed up reaching equilibrium without changing the final ratios.
Increased pressure favours higher NH3 percentages, as would be expected; at 800 atmospheres and 500 C the equilibrium is 51% NH3 which demonstrates
why the H-B process is run at high pressures. |
Damn, you're right. I figured for sure that reaction couldn't be occurring, because that was never given in any of the products in the papers I read
regarding catalytic oxidation of ammonia. But then I realized, no shit, that's because there's OXYGEN in the mix along with HYDROGEN at HIGH
TEMPERATURES. Gee, I wonder where all the hydrogen went?
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chief
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@Melgar: You have a reliable source of calcium nitrate ?
==> Since CaSO4 is nearly insoluble, the following should/could work: Ca(NO3)2 + H2SO4 ==> 2 HNO3 +CaSO4 ;
the CaSO4 could be let settle down or pressed out, and ready would be the conc. HNO3 ...
[Edited on 5-3-2010 by chief]
[Edited on 5-3-2010 by chief]
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quicksilver
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If you live in the US you can't miss calcium nitrate.....especially in rural areas. They (The magic Fertilizer In$titute) found they could make MORE
money with bagged CaNO3 but it has a great deal of AN in it - it's called 15.5-0-0 and it's all over the SouthWestern US. To get AN now you have to
(in my area) order one acre at least (300lbs) and it's always delivered unbagged. The companies agreed NOT to bag it now. So you better damn well have
a feed trough and a way to cover it. PLUS, you have to sign a chit saying "I am a good boy or girl and I won't do anything with this except burn the
Hell out of my soil". If you even attempt to order outside of turn over season they laugh in your face and hang up.
Oh and 15.5-0-0 is totally legal and righteous. No one will flip out. You'll start seeing it all over eBay because it's like $27 a bag!!!! They put so
much clay on it you can build a sand castle while you wait for your nitrate to clean up. 
[Edited on 5-3-2010 by quicksilver]
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Melgar
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| Quote: Originally posted by chief | @Melgar: You have a reliable source of calcium nitrate ?
==> Since CaSO4 is nearly insoluble, the following should/could work: Ca(NO3)2 + H2SO4 ==> 2 HNO3 +CaSO4 ;
the CaSO4 could be let settle down or pressed out, and ready would be the conc. HNO3 ... |
Heh, yep, that was the first thing I did last week when I got home with my bag of calcium nitrate. Yielded a nice clear acid too; I was afraid I was
distilling water until I took off the vacuum and white vapors started drifting out.
My dad used to be able to get ammonium nitrate, in those huge-ass fertilizer spreaders. Once I filled up a five gallon bucket with that stuff and
stuck it in the shed, but then quite a long time later when I went back to get it, it was gone. My dad said he got rid of it... damn it.. Now he
says they can't get it anymore. Well, presumably it's still possible to get it but it's so much paperwork that everyone just uses something else.
I'm still interested in ammonium sulfate, but now more as a source of ammonia and sulfuric acid. And it was cool to at least get a little bit of
ammonium nitrate from that reaction. 
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quicksilver
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There is some recent interesting history about AN. In New York there was this congressman named Shumer (D-NY) who tried to have it banned totally (The
Calcium Nitrate is calcium-ammonium nitrate - a big mix of nitrates with a lot of clay) But the rural states flipped. To ban nitrates could actually
destroy agri-business-states checker-boarded all over the US. So his "Ban" was shut down hard!
But the "Fertilizer Institute" got a great deal of pressure from the Fed to do something. So they put together a campaign called "Be Aware for
America" and generally told folks to watch WHO was buying. well no one likes doing extra work so that fizzled. but since the prill towers don't care
what drops down them, someone came up with putting come clay and mica and AN with CaNO3; the idea being that people with crazy ideas wouldn't play
with water and filters and evaporation, etc. That works fine for some states but some have vast chemical plants and the AN was a by-product of their
endeavors. All they needed was a tower. So ammonium nitrate is still being made at the hundred ton level in the US but a lot has shifted to Northern
Europe.
Ammonium Nitrate is REALLY only needed by a few crops. Berry's benefit & tobacco, and in areas with a Fall with few leaves to mulch the soil with
sharp season-crop demands. So realistically If you grow corn or perhaps cotton in sand soil conditions, you'd want AN - & you can still get it but
you can't buy it bagged any longer. It is delivered only at the acre level (which is (about 300lbs). But C.A.N. does everything that AN would and they
made it the same size so the rollers don't need bigger holes or any alteration in equipment.
In terms of quality Yara, the Norwegian company produces the best small bagged product.
http://www.yara.co.uk/about_us/history/corporate_history.htm...
Hydroponics growers knew about that for some time. We have an FFA & 4H club very close and our Fair has some serious contestants. There was a 100+
lbs hydroponically grown pumpkin last year: the product WORKS!
[Edited on 5-3-2010 by quicksilver]
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grndpndr
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Yara sent a 4 0z sample of thier solution grade calcium nitrate double salt its very nearly completely soluble
OT .01%.I dont think thats alot of clay to worry bout
but as I said its a dbl salt 5Ca(NO3)2-NH4NO3.-10h20
.If interested Im sure its available about anywhere "yara" Viking Ship Brand Calcinit ,'solution grade' 15.5-0-0 +19Ca.If Ebays to be trusted 35lbs
shipped for $38 doesnt sound like gouging.Im not aware of how it will react attempting to synthesise AN
via ammonium sulfate or HNO3 using the double salt and H2SO4.But I intend to at least try distilling HNO3 with the sample im not lookin to make
FRNA/WFNA the 68% azeotrope will do for most of my needs.Simplicitys sake Ill use dilute H2SO4.I really cant forsee any insurmountable problems but
thats the reasoning for the post. Thanks.Maybe some of the clay
problems can be avoided sticking to solution grade calcinit.Ive heard the DBL salt calcium nitrate in question referred to as ammonium calcium nitrate
to differentiate it from the clay laden CAN, different animals altogether according to MSDS/manufacturers.
[Edited on 3-4-2010 by grndpndr]
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