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Author: Subject: Nitric Acid Synthesis
Picric-A
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[*] posted on 30-7-2008 at 01:06


can ammoniium nitrate be used to make nitric acid via H2SO4 + nitrate salt method?
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[*] posted on 30-7-2008 at 10:30


Hi everyone, I have been a non member for a while reading and learning chemistry. This is a great place to learn.

I have a question about making nitric from ammonium sulfate.

In a sealed vessel, would it be possible to heat ammonium sulfate to decomposition but keep the temperature below H2SO4's boiling point.. so about 280-290 C. Then have an ozone generator in the reaction chamber to oxidize the ammonia given off? Producing ammonium nitrate which would get converted to nitric acid by the H2SO4.

Essentially the setup would be oxidizing the heck out the ammonium sulfate to end up with nitric and sulfuric acid.

I'm finding it very very difficult to locate any relatively pure quantity of any kind of nitrate. So I'm exploring other methods. I realize that this method would require a lot of ozone to produce any significant amount of nitric acid.

Thanks
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[*] posted on 30-7-2008 at 13:17


Quote:
Originally posted by Picric-A
can ammoniium nitrate be used to make nitric acid via H2SO4 + nitrate salt method?
Picric a


Yes but you may have to adjust the amounts.

Quote:

In a sealed vessel, would it be possible to heat ammonium sulfate to decomposition but keep the temperature below H2SO4's boiling point.. so about 280-290 C. Then have an ozone generator in the reaction chamber to oxidize the ammonia given off? Producing ammonium nitrate which would get converted to nitric acid by the H2SO4.



I'm not sure if that method will work at all but if it somehow manges to work you will be getting huge volumes of NOx fumes . It's quite possible all the nitric acid will decompose at 100+ degrees.




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kilowatt
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[*] posted on 30-7-2008 at 15:16


You'd need one heck of an ozone generator to oxidize enough ammonia to make significant mole quantities of NO2/nitric acid. Ozone generators are normally pretty weeny unless we're talking about a large UV unit. It would be much easier and more energy efficient to use regular air and a catalyst from an old catalytic converter at about 500°C and 50-150psi. The honeycomb catalyst is very easy to cut and make fit into a pipe or other reactor of your making.



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[*] posted on 30-7-2008 at 16:00


Quote:
Originally posted by kilowatt
You'd need one heck of an ozone generator to oxidize enough ammonia to make significant mole quantities of NO2/nitric acid. Ozone generators are normally pretty weeny unless we're talking about a large UV unit. It would be much easier and more energy efficient to use regular air and a catalyst from an old catalytic converter at about 500°C and 50-150psi. The honeycomb catalyst is very easy to cut and make fit into a pipe or other reactor of your making.


Nitric Acid can be produced in a useful quantity by using a corona or arc discharge. Corona discharge is employed in many ozone generators and can be easily achieved with a neon sign transformer. (You would use it oxidize the N2 in the atmosphere, not ammonia, as this would waste oxygen.)

A catalytic converter will not work, as it is designed to reduce NOx species to N2 and xO2. (If it is a three-stage converter, as cars employ.)

I do recall that copper can catalytically oxidize ammonia to NOx, however it is so exothermic that the copper will melt. Creative mounting of the copper and flow regulation of the ammonia and oxygen feedstock may be useful.




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[*] posted on 30-7-2008 at 17:05


Quote:

A catalytic converter will not work, as it is designed to reduce NOx species to N2 and xO2. (If it is a three-stage converter, as cars employ.)

Automotive catalytic converters use the same catalyst materials (platinum or platinum/palladium) as the Ostwald Process for oxidizing ammonia to NO2. As a demonstration of their oxidizing property just shoot some propane or butane through one of the honeycombs, and it will be oxidized without combustion bringing the catalyst to a bright red heat (has to be hot to start the reaction though). I have done this routinely to check if old catalysts are still active.




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[*] posted on 31-7-2008 at 17:57


Quote:
Originally posted by kilowatt
Quote:

A catalytic converter will not work, as it is designed to reduce NOx species to N2 and xO2. (If it is a three-stage converter, as cars employ.)

Automotive catalytic converters use the same catalyst materials (platinum or platinum/palladium) as the Ostwald Process for oxidizing ammonia to NO2. As a demonstration of their oxidizing property just shoot some propane or butane through one of the honeycombs, and it will be oxidized without combustion bringing the catalyst to a bright red heat (has to be hot to start the reaction though). I have done this routinely to check if old catalysts are still active.


Of course it oxidizes fuel. Three-way catalytic converters are designed to do three things:

1. Oxidize any unburnt fuel to H2O and CO2.
2. Oxidize CO to CO2
3. Reduce NOx to N2 and xO2

Some older cars may use only a two-way converter, however most if not all modern cars use a three-way. You should check to see which one you have before using it for nitric acid synthesis. Some three-way converters use two chambers as well, one for reduction, one for oxidation.\

Ancillary: Old propane catalytic heaters may be more useful and easier to acquire. (Depending on circumstance.)

[Edited on 7-31-2008 by ShadowWarrior4444]




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kilowatt
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[*] posted on 31-7-2008 at 18:06


If you use the latter catalyst from a 3 stage converter it should work fine. Every one I have opened has two, presumably one for NOx reduction, and one for the other two functions. I haven't actually done the synthesis yet though, too much else going on.:(

[Edited on 31-7-2008 by kilowatt]




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[*] posted on 19-8-2008 at 03:52


OK! to stretch the topic a little.

I have access to 60% HNO3 at sensible prices and would like to concentrate some to 95%.

Would a reasonable method be vacuum distilation at a moderate vacuum using an aspirator?

I'm aiming to have a couple of litres of product from a quickfit style apparatus.
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[*] posted on 19-8-2008 at 04:15


Quote:
Originally posted by Contrabasso
OK! to stretch the topic a little.

I have access to 60% HNO3 at sensible prices and would like to concentrate some to 95%.

Would a reasonable method be vacuum distilation at a moderate vacuum using an aspirator?

I'm aiming to have a couple of litres of product from a quickfit style apparatus.


You could try a Google on 'nitric acid distillation', collect up a few ideas and then come back to this board with some idea of what you are trying to do.
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[*] posted on 19-8-2008 at 04:16


Without concentrated sulphuric acid you will never go higher than 68%, due to the azeotrope of water and HNO3. I'm not sure about the exact percentages at other than atmospheric pressure, but I'm quite sure that you will not even come close to 95%.

If you have concentrated sulphuric acid, then you have an easy job. Just mix equal volumes of acid and slowly distill, you do not even need a vacuum distillation, normal pressure is suitable. Keep on distilling, as long as the temperature remains below 90 C. Suddenly, at a certain point, the temperature fairly quickly rises. That is the point where you should stop. You can reuse your sulphuric acid, by boiling it down after the distillation and then again mixing it with the nitric acid.

The acid, obtained in this way is yellow, due to some dissolved NO2. Be aware with the storage of highly concentrated HNO3. I have appr. 30 ml of 90+ % HNO3 and I need to unscrew the cap every few weeks, due to pressure buildup. Not good at all.




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[*] posted on 19-8-2008 at 05:01


There are plenty of recipes on the Internet along the lines outlined by Woelen and they will yield an acid of very high purity.
I can't remember the details now, O level chemistry in the late 1970's, but very concentrated nitric acid is an appreciably more vigorous oxidising agent compared with normal 60 - 70% lab acid.
A small pile of warm, dry sawdust will catch fire on adding a few drops of the concentrated acid.
I think having a look through some old practical books will throw up some interesting demos :)
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[*] posted on 20-8-2008 at 14:29


Quote:
Originally posted by ScienceSquirrel
There are plenty of recipes on the Internet along the lines outlined by Woelen and they will yield an acid of very high purity.
I can't remember the details now, O level chemistry in the late 1970's, but very concentrated nitric acid is an appreciably more vigorous oxidising agent compared with normal 60 - 70% lab acid.
A small pile of warm, dry sawdust will catch fire on adding a few drops of the concentrated acid.
I think having a look through some old practical books will throw up some interesting demos :)



I am in possesion of at least 50-60yr old Holt-Rinehart-Winston, I believe a college chemistry 100 level lab manual.The glassware etc is rudimentary But the illustrated labs such as the Nitric acid
synthesis using an alchemists type glass retort with a small snug fitting round bottom flask in an ice bath to catch the
distillate.Whats astounding is the list of chemicals assigned to each student.As an amateur you'd be lucky to be able to steal some of these things from a well stocked university lab.
Red white P,uranium ore,pott cyanide?

If I were to start again Id likely use that old chem manual method to low buck small amts 90%+ nitric acid although the same can be done with very crude equipment and patience.

PVC tape ad PVC tubing lasts a few distillations before it gets soft when hot then brittle when cold and needs replaced but it did work for small amounts of fumng red nitric clearly stronger than the 70%.

[Edited on 20-8-2008 by grndpndr]

[Edited on 20-8-2008 by grndpndr]
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[*] posted on 20-8-2008 at 20:26


Quote:
Quote:

Automotive catalytic converters use the same catalyst materials (platinum or platinum/palladium) as the Ostwald Process for oxidizing ammonia to NO2. As a demonstration of their oxidizing property just shoot some propane or butane through one of the honeycombs, and it will be oxidized without combustion bringing the catalyst to a bright red heat (has to be hot to start the reaction though).


Oddly enough a column of molecular sieves will do the same thing to propane. I have no clue how though.




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[*] posted on 21-8-2008 at 05:15


Zeolite is a catalyst too. It is used specifically in some catalytic cracking of hydrocarbons.



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[*] posted on 21-8-2008 at 12:30


Quote:

Without concentrated sulphuric acid you will never go higher than 68%, due to the azeotrope of water and HNO3


Not entirely true. Magnesium nitrate and similar (compatible to HNO3 ofcourse) desiccants will break the azeotrope. It works most favorably with the DCM extraction method. They have the added bonus of being more easily recycled, plus you can make magnesium nitrate easily from the carbonate and dilute nitric acid.
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[*] posted on 21-8-2008 at 17:16


Quote:

They have the added bonus of being more easily recycled, plus you can make magnesium nitrate easily from the carbonate and dilute nitric acid.

That forms magnesium nitrate hexahydrate though, which is not as strong a dessicant. It cannot be dehydrated by heating alone; it will just decompose to magnesium oxide and NO2/O2/H2O vapors. How can it be converted to anhydrous magnesium nitrate besides with anhydrous HNO3?




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[*] posted on 21-8-2008 at 18:50


Magnesium nitrate doesn't have to be dehydrated completely to have sufficient dehydrating power to break the azeotrope of nitric acid and water. IIRC, even the trihydrate will do the trick. It can only be conveniently obtained anhydrous by heating alone AFAIK, in double salt form with NH4NO3. The patents give good information on this.
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[*] posted on 22-8-2008 at 10:00


Thanks all, 98% H2SO4 is available from a few suppliers here but nitric rarely exceeds 50%. SO H2SO4 + 50% HNO3 will distil off 98% HNO3 then a largely water portion will come over leaving conc H2SO4

Looks like a simple distillation taking the water fraction out in the middle
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[*] posted on 22-8-2008 at 10:21


As long as by "simple distillation" you mean fairly easy, but with a reflux distillation as opposed to a simple distillation.;)

Quote:

The patents give good information on this.

I beg to differ; the patents relating to anhydrous magnesium nitrate describe methods with a pulse combustion drier. Double salts with ammonium nitrate were briefly referenced but not described.

[Edited on 22-8-2008 by kilowatt]




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[*] posted on 22-8-2008 at 21:00


The attached patent confirms what I just said above.

You are onto some idea of baking the nitric out of a nitrate
like baking out the sulfuric from a sulfate, in order to cycle through ammonium nitrate and recover ammonia and convert it to nitric......and the energy requirement for all the requirements of that loop are economically infeasible
as well as being a technical nightmare. So I am not even
suggesting usefulness in that regard.

But if you want something to break the azeotrope,
Magnesium nitrate will do it and it doesn't need to be anhydrous. IIRC there are other patents also which
describe this usefulness and it is actually more thermally efficient than H2SO4 on the regeneration of the dessicant.

It hasn't been the source of any experiments by me to determine if it is workable, but the anhydrous double salt of magnesium nitrate and ammonium nitrate may possibly also
break the HNO3/water 68% azeotrope. This would make an interesting experiment. See the patent US3173756 anhydrous double salt of claim 11 , NH4Mg(NO3)3 mp. 167C
I have speculated that the double salt forms under only basic conditions, and separates into a simple mixture of discrete salts under acidic conditions. If my hypothesis is correct, then this would provide access to the dehydrating
potential of the anhydrous magnesium nitrate supplied as
the predominant weight percentage component of the
double salt, which is the only practical means of supplying an anhydrous magnesium nitrate component, shielded and contained within a double salt form.

http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
But by all means if you have a better idea, let's hear it:D


[Edited on 23-8-2008 by Rosco Bodine]

Attachment: US2463453 Magnesium nitrate for HNO3 concentration.pdf (265kB)
This file has been downloaded 655 times

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[*] posted on 23-8-2008 at 11:23


Correction: the patents I was able to find on my own.:P

Would hygroscopic sulfates like copper sulfate also work for breaking the azeotrope?

[Edited on 23-8-2008 by kilowatt]




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[*] posted on 23-8-2008 at 12:06


To greater or lesser extent there is usefulness for many of the dehydratable salts, and for mixtures, eutectics and
double salts, since there are combinations which dehydrate completely and at much lower temperature than
would the single salt. In some of these schemes, the dehydration works by one salt substituting for the water of hydration which would normally be bound in another.
Magnesium nitrate and calcium nitrate, zinc nitrate, ammonium nitrate are candidates. The more usual sodium and potassium nitrates can also be useful as components
in eutectic mixtures, and the lowered melting point facilitates the thermal dehydration occuring at a much
lowered temperature. Some presence of a basic salt
in small amount is probably also involved in lowering the melting point and facilitating the dehydration, accounting for the observation that the desired effect only seems to
occur in basic mixtures, the mixtures being disrupted by
acidic conditions, which can lead to the distinctly separate
hydrates crystallizing out separately as a mixture, no longer a eutectic or complex double salt, but the common hydrates appearing as a mixture of the usual hydrate crystals.
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[*] posted on 25-8-2008 at 17:16


Today I produced 150ml of fuming nitric acid with a density of 1.48g/l. The distillation setup was very simple; it consisted of a portable electric stove top element, a 12L high quality stainless steel pot, and a gallon corningware glass bowl filled with ice water. In order to to collect the distillate, I suspended an glass cup wrapped in rockwool insulation and Al foil. 500g (excess) of KNO3 was added to the pot, then 250 ml of Drain Opener was added (I can get this stuff as I have a plumbing ticket). Heating commenced and the icewater bowl was put onto the pot. Fumes were seen condensing onto the cold glass, and these droplets fell into the insulated
cup, after 1h heat was removed and the nitric acid was measured. I plan to water down this acid, as I do not need it so strong (down to 70% for me). I intend to now make some Mono Nitrotoluene, and then reduce to P-toluidine using Sodium dithionite (Rust Out)........has anyone tried this reduction before?
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[*] posted on 26-8-2008 at 08:50


A high temperature arc discharge will produce NO, a corona discharge will produce ozone.


There is a wonderful science experiment you never see anymore. that's running a Jacobs ladder in a clear plastic tube, after a few minutes you can't see thrue the tube anymore, from the NO gas.

This was actually a method of production of nitric acid and nitrates at the turn of the 20th century. What I find interesting is that its a more efficient process than whats used now, but uses a more expensive form of energy (electricity)

I'm presently putting together a system that will give me All the nitric acid and nitrates I might ever want !

when I'm closer to finishing I'll post some photo's
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