Sciencemadness Discussion Board

Building an Ostwald reactor

plante1999 - 9-2-2013 at 14:10

So, I re-started my Ostwald reactor project. I had already made some nitrate, but the yield was low, and I found the ammonia to be too concentrated. I also found that pressurized ammonia was WAY better. Today, I bought PVC pipes for house water line. 5/8 O.D. but is sold as 1/2. I also bought a few PVC elbow. Found that borosilicate glass softened, and on the pressure may make hole in the reaction tube, I tried copper tube, but the heat transfer was way too fast, the tube was not even dull red, and the two PVC elbows had already melted...
I have platinized asbestos as the catalyst that work very well and a 50 gallon air tank for my experimentation, with variable pressure adjustment, from 1 to 100 PSI. I also have 7 feet of PVC tubing and an old fire extinguisher as the tank. However I would like a valve instead of a burst of gas, as such I could get a perfect flow.
My project consist to make a complete system, I would plug the air line to it, regulate ammonia flow and lets running, a system of about one cubic foot. It may, or may not be pressurized, all my actual pieces can handle 400 PSI, but some part I could add may no be as resistant.

Now, here is the actual problem I have:
I need a valve to put on the fire extinguishor, a valve that handle 200 PSI, or a new gas tank

A way to fill the ammonia tank with ammonia

A quartz, or ceramic tube that have 5/8 O.D, as copper transfer heat too fast, and borosilicate simply soften and become dangerous.

I have a very small budget

What is good:
I have a good supply of air

A lot of random iron pieces for the frame

7 feet of PVC tubing, suitable for nitric acid and NOx

Platinized asbestos

Nichrome wire heating element from an old stove

A LOT of asbestos

A 60 year old fire extinguisher

A camera to take pictures for all of you (If you want me to take a picture of something, ask me)


phlogiston - 9-2-2013 at 17:16

What if you put some isolation around the copper tubing? Or perhaps another metal that doesn't conduct heat so well?

[Edited on 10-2-2013 by phlogiston]

plante1999 - 9-2-2013 at 17:30

I don't think isolation would help, I would think it would be worst. Another metal might be good, But we need a metal that do not oxidize readily, as TM oxide catalyze formation of N2 instead of NO. Metals like aluminium are good (because there oxide is rather inert), and Gold is good, because it doesn't oxidize readily.

elementcollector1 - 9-2-2013 at 18:21

Gold plating, maybe?

plante1999 - 9-2-2013 at 21:09

With help of some members here, I was able to find a way to turn my extinguisher to a gas tank for 20$. The tank can handle 400 PSI, which is way more than needed. I also found a way to make gas absorption system, without any hassle of opening the reactor, like industrial set-up. I only need to open a valve to get the acid, and another to add water. Someone also gave me the idea of a safety gas release valve, which I will add for safety. All tubing/valve before the reaction tube will be made of S.S and teflon. After the tube everything would be made of PVC with a gas absorption system similar to this one:

The green part is a filter, the brown is quartz sand, the red X are valves. The top one is used the refill with water. There is three absorption system, the last one with urea to neutralize the gases. There is a valve at the end of the last absorption system to regulate pressure, a pressure gauge should be added for safety.

Now there is still three main problem:
I still need a 5/8 O.D (16mm) quartz/ceramic tubing by 12 inch (If someone have one, and want to donate it or sell it cheaply, send me a U2U)

I need to make liquid ammonia with calcium chloride and snow

I need more funds, Only the S.S cost 56$, so yea. I will try to sell a few things I do not need anymore to get more fund for this project, but one can donate, or buy chems/material from me to fund the project. I talked about that with bromic acid, and come to conclusion I needed fund raising.

[Edited on 10-2-2013 by plante1999]

[Edited on 10-2-2013 by plante1999]

blogfast25 - 10-2-2013 at 05:37

Photos would make things a lot clearer, in my opinion...

plante1999 - 10-2-2013 at 14:21

I did some work on the reactor today, I made the three gas absorption chamber, I only need 6 valves and this part is done. I also took a picture of the very old fire extinguisher (dated from 1954 or 1964) and the nichrome wire. The chambers look sturdy, I got some sponge for the filter, but I'm not sure they are suitable.
Actually the fire extinguisher is tested at 500 PSI.


[Edited on 10-2-2013 by plante1999]

phlogiston - 11-2-2013 at 01:22

What is your source of ammonia and how are you planning to fill the tank with it at pressure?
Also, are you planning to have the reaction tube at above-atmospheric pressure?

plante1999 - 11-2-2013 at 04:42

I will make ammonia using Drano and urea, and I will condense the ammonia in the cylinder. When condensed, I will put the valve on the cylinder.

The system will probably be pressurized. The stainless I'm planning to use is rated at 350 PSI, and the PVC 400. The maximum pressure I would possibly use is 150 PSI, but I will probably use 50 PSI.

blogfast25 - 11-2-2013 at 05:58

Small leaks of ammonia may render your process very stinky. Just filling up 0.5 L bottles with 0.88 SG ammonia solution stinks out my warehouse!

Your ammonia condenser for example is unlikely to trap ALL NH3(g), so you need to deal with the 'off gases'...

[Edited on 11-2-2013 by blogfast25]

Doc B - 11-2-2013 at 07:07

An LPG gas bottle is refillable, fitted with a valve, available readily and in various sizes, cheap even if bought new.

To fill the ammonia at pressure I would suggest a diaphragm pump. I have one that both sucks and blows (teehee, who thought that was possible?) it's intake and output are inline so that it blows what it sucks at pressure and vise versa. If you would like more details let me know.

Regarding the tube, would ceramics be a suitable alternative?

plante1999 - 11-2-2013 at 09:13

Quote: Originally posted by blogfast25  
Small leaks of ammonia may render your process very stinky. Just filling up 0.5 L bottles with 0.88 SG ammonia solution stinks out my warehouse!

Your ammonia condenser for example is unlikely to trap ALL NH3(g), so you need to deal with the 'off gases'...

[Edited on 11-2-2013 by blogfast25]

Yea the filling will be done outside, and when the bottle will be closed, it will be put on the system, inside.

Doc B, I'm not sure a diaphragm pump can make enough pressure to make liquid ammonia.

Ceramic would be a suitable alternative.

Doc B - 11-2-2013 at 10:26

If the vapor is cooled to 0'C then you'd only need 45psig, being only twice atmospheric pressure.
On p7 you'll see the pump and if you can find the specs for the Dynavac heavy duty vacuum pump/compressor it will allow you to calculate temperature to pressure ranges that might be feasible for you. Plus I'd really like to know the specs as I picked one up for $60 and haven't been able to find any such data online or elsewhere so please let me know if you do. ;)

Ceramic pipe is available at plumbing and gardening stores or perhaps even scrap from residential or industrial construction etc. might be worth checking out?

Doc B - 11-2-2013 at 10:36

You could also find a ball valve in the PVC or plumbing section of the hardware store. I don't know about the PVC one but expect it would be rated at pressures similar to the pipe which would be a go, if there is one that fits. The other option is the chrome plated Teflon ball type available in many sizes for less than $20. Hope that's some help to you, good luck!

Magpie - 11-2-2013 at 13:06

Quote: Originally posted by plante1999  

Now, here is the actual problem I have:
I need a valve to put on the fire extinguishor, a valve that handle 200 PSI, or a new gas tank

A way to fill the ammonia tank with ammonia

A few years ago I made a very small tank out of a pipe nipple to contain liquid ammonia. The generated gaseous ammonia was liquidfied by condensing it in a Dewar containing solid CO2/acetone. The liquid NH3 was then poured into the tank equipped with a valve. I describe this in a forum thread somewhere. Garage chemist was also doing this at the same time only he caught the gaseous ammonia in a large plastic bag. This was then compressed and liquified in a lecture bottle using a fridge compressor, IIRC. He has also reported his results on this forum.

Be careful that the wetted surfaces of your ammonia carrying pieces are not composed of copper or brass or they will corrode.

I bought a special pressure gauge (0-450 psi) and pressure relief valve (350 psi) having wetted parts made of ss for handling ammonia from this vendor:

You should be able to find a small ss needle valve for not too much money.

You should pressure test your pressure vessel and piping using a liquid to 150% of the intended operating pressure. This is standard practice per ASME. DO NOT TEST WITH A GAS - TOO DANGEROUS!

Quote: Originally posted by plante1999  

What is good:
A LOT of asbestos

I'm jealous. :)

[Edited on 11-2-2013 by Magpie]

[Edited on 11-2-2013 by Magpie]

phlogiston - 11-2-2013 at 13:14

Perhaps you can use the quartz glass tube from a tubular halogen lamp?
Alternatively, perhaps you can drill a hole through a resistant brick (or file a little gutter on the surface of two blocks and fit them together, so you can more easily (dis)assemble the reactor, having access to its entire length.

In what form is the asbestos you have?

Magpie - 11-2-2013 at 13:25

Maybe I just missed it but what is the operating temperature and pressure of the reactor vessel?

plante1999 - 11-2-2013 at 14:00

Doc B, I'm intended to liquefy the ammonia. I have many format of asbestos, such as sheet, paper, wool, plate etc...
Maybe I didn't specify, but I intend to use two of these connector for the system: They are avaible for 16 mm and 10 mm:

The temperature is 800 to 900 centigrade.

I do not own dry ice, and not sure if I can get some, but I was planing to use CaCl2 + snow, outside, when the temperature will be - 30. The mixture is supposed to get to -40.

phlogiston - 11-2-2013 at 14:03

Then perhaps you can fashion a reaction channel out of a few sheets of asbestos plate? Take two large sheets and sandwich two small sheets in between, leaving a channel of the desired diameter in between.

Magpie - 11-2-2013 at 15:41

I have little doubt that you can make NO/NO2/N2O4 with your Ostwald reactor, even at atmospheric pressure. Although I didn't see this mentioned I assume you plan to use this to make HNO3. I think that this is where the real challenge will be. Industry uses an efficient gas absorbtion tower that has many plates or much packing (ie, is tall), is cooled, and is operated at about 100 psi according to Shreeve.

Granted Shreeve is an old reference. I would check the most recent Kirk-Othmer or Ullman encyclopedias.

Don't get me wrong, I admire and support you giving this a try. I just want to help you think this project through before you spend too much time and money. ;)

plante1999 - 11-2-2013 at 15:48

Well, as you may not know, I already tried the process, and got some yield at atmospheric pressure. I made 50g of sodium nitrate, which I used to make nitric acid, the same that burned my face, so yea. Like I said, I'm planning to run it at pressure, about 50 PSI to 150.

You can read more here:

Yea, money... I can still use the reactor to make other chems, like sulphuryl chloride or mercury... I simply need to change the reaction tube, and wash everything.

If I make lab scale industrial processes book, I assure you I also use most industrial chemistry encyclopedia, such as Ulmann's.

[Edited on 11-2-2013 by plante1999]

Magpie - 11-2-2013 at 17:22

Here's a supplier for quartz tubing:

Magpie - 11-2-2013 at 21:41

Here's some ammonia liquefaction experience that may prove useful:

plante1999 - 12-2-2013 at 04:55

Interesting, I wanted to put a filter for the gas, but with all this rust, I would probably need a S.S tank, as in most industrial chemistry books, they explain the catalyst poisoning by dust in the ammonia flow. I wonder if the supplier Magpie showed would ship to Canada.

plante1999 - 12-2-2013 at 09:54

I made a list of item needed, I may have forgot some. I didn't include cheap one I already had (PVC pipes for example).
Some have links, some do not.

Hope it help to clear out a few things. I'm also trying to make a diagram for the system, one with most basic material, one with more material.

Attachment: Here is a list of material I would need to build the reactor.docx (12kB)
This file has been downloaded 360 times

Magpie - 12-2-2013 at 17:43

Omega is another good supplier for technochemistry projects. Here's what they have in small diameter ceramic tubes:

Also see:

I know these suppliers' items may be outside of your budget. I'm just trying to give you some options and ideas.

Magpie - 12-2-2013 at 20:05

In my cursory reading of Ullman's I see that the ratio of ammonia to air is important (if not critical), which I think you have already discovered. How do you propose maintaining this ratio?

One advantage is that your liquid ammonia will exert a constant pressure as long as its temperature is kept constant. You could use rotameters to meter these 2 gases, but maybe there is a simpler and more elegant way. Will you use an air compressor to provide pressurized air?

One advantage of operating your reactor above atmospheric pressure is that you will have plenty of pressure to drive the NOx through the absorber. There are, I suppose many different ways an absorber could be made, cheaply or otherwise. Much room for creativity here, I think. ;)

plante1999 - 13-2-2013 at 04:44

Well, the three absorber are mostly made, I only need to make a gas dispersor in them. They are made of cheap PVC, you can see them on the first page. The ammonia air ratio is very critic as showed by my experiments too. I had thought, that if ammonia can keep a constant pressure, and keep a constant air flow, the gas mix would probably be similar trough all the experiment. Yes, a 50 gallon air compressor, with variable pressure adjustment.

I don't see how I could afford rotameters. I guess I will have to rely on constant pressure. And thanks for your ideas, they are helpful.

blogfast25 - 13-2-2013 at 09:20

Quote: Originally posted by Magpie  
One advantage is that your liquid ammonia will exert a constant pressure as long as its temperature is kept constant. You could use rotameters to meter these 2 gases, but maybe there is a simpler and more elegant way. Will you use an air compressor to provide pressurized air?

As your liquid ammonia evaporates, the temperature of the liquid will decrease unless you constantly put in the Enthalpy of evaporation. At low flow rates (of ammonia gas) and provided you have a large mass of liquid ammonia this effect may be negligible. It would be worth calculating though...

[Edited on 13-2-2013 by blogfast25]

Magpie - 13-2-2013 at 17:16

Here's some ammonia flow regulation experience that should be useful:

I especially thought the last comment appropo.

[Edited on 14-2-2013 by Magpie]

plante1999 - 19-2-2013 at 09:15

Could anyone test for reactivity of nitric acid of various concentration on 304 and 316 stainless steel? Maybe 5,15 and 50% acid?

I should get most of the stainless tubing/valves in the list soon, a very generous donation by doctorofphilosophy. I only have the quartz tubing, relieve valves and meters to find now.
I will try to find others things this week-end.

[Edited on 19-2-2013 by plante1999]

Magpie - 19-2-2013 at 09:32

Quote: Originally posted by plante1999  
Could anyone test for reactivity of nitric acid of various concentration on 304 and 316 stainless steel? Maybe 5,15 and 50% acid?

Have you seen this:

Both are excellent, at least up to 72F.

blogfast25 - 19-2-2013 at 12:39

It's supposed to passivate iron, is it not? But strong HNO3 is needed for that, IIRW...

Magpie - 19-2-2013 at 12:53

Nitric acid is also used to passivate stainless steels.

Here's an even better supplier of quartz tubing. They will also do glassblowing. It may take some coaxing for small jobs, however.

plante1999 - 19-2-2013 at 14:00

Thanks for the information. I will see what I can do for the quartz tubing, the sand, filter and others. This wee-end, I may try to condense ammonia with a calcium chloride/ice mixture. I will probably finish the absorbers too.

The ammonia tank will be made of stainless steel, 2 inch by 6 with cap and reducer. Magpie test showed iron impurity that could really harm the system, even with filtering of the gases.

Magpie - 19-2-2013 at 16:00

Since appropriate rotameters and pressure regulators are so expensive I understand if you are not going to have them. Are you planing to just tune the the ammonia/air ratio based on the color of the reaction products, or what?

burning ammonia is potentially explosive
ammonia is toxic

NOx can be toxic

You already know these things. And I'm sure you are sensitized due to your recent accident, of which I was sorry to hear. I just repeat this here to encourage you to be very careful.

plante1999 - 19-2-2013 at 16:19

The color of the reaction product would be useful, and the product analysis as well. burning ammonia is explosive when above 12% in air, I'm planning to run way lower than that, because I need an oxygen excess. When nitrogen monoxide is formed, it need to be oxidized to NO2 (need air), when the NO2 is dissolved in water it release NO, which need to be oxidized back too. I will probably run at 2-5% ammonia, if I want a good yield. Lower ammonia also increase the yield, because ammonia react with nitrogen oxides, to make nitrogen.

Liquid ammonia is dangerous, and NO2 too, but they are not my main concerns to be honest. I have worked with stronger stuff, I assure you. If I can find these item for under 50$, I will buy them, but I do not feel like they are necessary. My main concern is bursting of the combustion tube for a reason or another. As such, I will use 1/4 steel shield on possibly dangerous parts.

What is funny with my accident, is that I got the burns with completely homemade nitric acid, which I was quite proud of. The nitrate ion had bean made with my Ostwald tries. These accident do not only left physical harm, but I assume you know that.

On a side note, the cooling of the absorbers will be performed by a ice-water bath. This same bath will Heat the cooling ammonia, to maintain a constant pressure.

Magpie - 19-2-2013 at 17:07

Even if you cannot make strong acid you can make nitrates. From these you can make strong acid, as you have already done.

This is a very interesting project and I wish I could be there to work on it with you. I look forward to your progress and hope to see some pictures. ;)

plante1999 - 19-2-2013 at 17:49

That is what I'm thinking, but hopefully I will be able to make strong nitric acid directly. I can clearly see that you would like to work with me on this! Now that I have a camera, it is easier for me to take pictures, a lot easier. If you want me to take a picture, simply ask me, I would be glad to take a picture in the same day.

One interesting part of this project is the fact that the reactor is multi functional. I could make many chemical with it, by simply changing the catalyst, and the gas reacting together. Sulphuryl chloride, mercury , acetaldehyde etc...

I hope to make something good, I like the absorbers I made at the moment, they feel sturdy and hole are well made (centered).

[Edited on 20-2-2013 by plante1999]

plante1999 - 4-3-2013 at 13:44

I got a good part of the stainless tubing in my mail today. In a few hour I should have finish to make the ammonia tank with teflon tape and some other part too, I will put pictures here. Sadly, the waiter is supposed to be hot during the week, as such only this weekend it will be tried to liquefy ammonia. In The main while I may try to fill it with sulphur dioxide to test for leaks.

phlogiston - 4-3-2013 at 15:54

the waiter is supposed to be hot during the week, as such only this weekend it will be tried to liquefy ammonia.

Serious mad scientists don't get distracted by a hot waiter so easily. Focus! Looking forward to your pictures though, especially if they also involve hot waitresses :)

[Edited on 4-3-2013 by phlogiston]

plante1999 - 4-3-2013 at 16:33

If I want to keep the temperature of the freezing mixture down I must do it on a cold day. Here is the Tank, it is about 15 inch height and 3 inch diameter on the cylinder and 4.5 on the valve. I love the industrial look of the stainless pieces. I will work on other connections during the week.

I changed the design (no teflon yet) There is a ball valve on top of the tank to be able to fill it with liquid ammonia easily, There is also the air valve on the right. I tried to put in evidence the outlets where the quartz tube should be. Near the tank there is an outlet which is where the absorbers will be connected.

[Edited on 5-3-2013 by plante1999]

plante1999 - 5-3-2013 at 16:03

So I continued to put teflon everywhere, then I tested with 100 PSI, at the valve there was some minimal leak, but at the tank the leak was huge, even at 30 PSI it was leaking badly, I re-added teflon tape, screwed it tightly and tested again but it was still leaking...

I guess I will need some sort of liquid sealant...

Vargouille - 5-3-2013 at 16:11

What you can do is use silicone grease to plug the leak. You should be able to get a nice little tub of it for a few bucks. If you need to find where the leak is specifically, you can cover the sealed tank in a thin layer of a solution of soap in water (without bubbles) so that when air comes out through the leaks, it'll make bubbles in the solution.

Magpie - 5-3-2013 at 16:39

As you know, plante, I have built an ammonia storage capsule out of threaded steel pipe. I also encountered leaking threads. I ended up using a liquid sealant which did eventually give me a seal. I have described said adventures in a thread to which I previously alluded.

I would recommend first trying a TFE paste pipe thread compound. I eventually ended up with Leak Lock, a joint sealing compound made by Highside Chemicals. This was recommended to me by a pipefitter who had experience maintaining an ammonia refrigeration unit.

When building my autoclave I ended up backwelding all of the threaded joints that I could.

For the most part I don't think threaded joints are meant for gases, at least not at high pressure. I know that the natural gas line coming into my house is threaded black iron, but that is fairly low pressure (1-2 psi). I don't think that the installers used any kind of joint sealer - they just reefed like hell to make a metal-on-metal compression seal.

Edit: I was wrong here. My natural gas line has a white liquid sealant at the joints - no doubt it is TFE.

One of the problems you will learn with threaded joints is that the threads can permanently deform making it difficult to seal when you try to unscrew and then rescrew the joint.

Welcome to the wonderful world of threaded joints! At one of my previous employers in the nuclear industry all pipe joints were were socket welds.

[Edited on 6-3-2013 by Magpie]

[Edited on 6-3-2013 by Magpie]

cyanureeves - 5-3-2013 at 17:12

wow i didnt know that about threaded joints i would always suspect dirty threads and cleaned them with a thread chaser. thread chasers bigger than an inch can be pretty expensive though but if clean threads and teflon dont cut it,then??

Magpie - 5-3-2013 at 17:19

Here's the thread telling of my experience building an ammonia capsule:

One extra problem with ss vs black iron, is that ss threads tend to gall, ie, "fret and wear away by friction" (Webster dictionary).
Fret = eroded.

cyanureeves - 5-3-2013 at 18:57

yes, yes of course it does sorry i forgot about ss threads and even some black steel as you called it back in 2005 will gall. if not oiled enough or threaded too fast one does get supervisor would chew my butt for causing shatter as he called galling when i threaded casing was cool seeing that pipe with frost harnessing ammonia.

plante1999 - 21-3-2013 at 19:09

I just got the leak lock, as reccomended by magpie. I'm away for three day, so I will only be able to work on it Monday.

plante1999 - 25-3-2013 at 17:12

I started leak-locking everything, it should be dry tomorow. I should also got the quartz tube and gauges fairly soon.
Hopefully I will be able to make a pressure test soon.

Then I will try to liquefy ammonia.

Zyklon-A - 28-2-2014 at 12:55

plante1999 , Have you worked on your ostwald reactor recently?
I'm considering building one of these soon.
[EDIT grammatical error]

[Edited on 28-2-2014 by Zyklonb]

plante1999 - 28-2-2014 at 15:19

U2U me please.