liquidlightning
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Platinized Asbestos
I just got a 10 grams of platinized asbestos. Know of anything interesting I can do with it? 5% Platinum, looks like steel wool. It is definitely
real, it ignites my butane torch.
[Edited on 16-9-2012 by liquidlightning]
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hissingnoise
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You could use it to oxidise SO<sub>2</sub> and prepare oleum!
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Lambda-Eyde
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You could, but Pt is easily poisoned. Vanadium pentoxide catalyst is a better choice for that reaction and also should be quite interesting to
prepare. See Fleakers thread on oleum. Preparation of SO<sub>3</sub> is not something to be taken lightly and should under no
circumstances be done without a fume hood.
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Endimion17
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Quote: Originally posted by Lambda-Eyde  | | You could, but Pt is easily poisoned. Vanadium pentoxide catalyst is a better choice for that reaction and also should be quite interesting to
prepare. See Fleakers thread on oleum. Preparation of SO<sub>3</sub> is not something to be taken lightly and should under no
circumstances be done without a fume hood. |
It's not a nerve gas, for god sake. Pretty much anything can be done withoud a fume hood, if the apparatus is properly designed and assembled,
and if the excess gasses are being taken care of properly by series of tubes leading outside.
Now, if someone is working with soda bottles and drinking glasses, it's easy to get poisoned. If one uses old fashioned corks and bungs, the poisoning
is less likely, but if one has a ground glass joint apparatus with Keck clips and joint lubrication, nothing happens.
Sulphur trioxide can be readily condensed and solidified, and excess sulphur dioxide can leave the apparatus through a tube.
There are way more dangerous experiments people do. SO3 synthesis is not one of them.
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plante1999
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Few days ago I also received 10g of 5% platinized asbestos. Many use can be mane from it but its mostly good for oxidation reaction. I'm also working
on something pretty interesting that should be revealed in a month or two.
I never asked for this.
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phlogiston
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Make nitric acid via the ostwald process?
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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plante1999
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Ok I'm a bit obligated to reveal the project I'm working on. I
started it a month ago I already made some experimenting with the Ostwald process but I do not have anymore ammonia (the reason for the post I need
ammonia fast). At the time the process is very successful.
Here a picture of my setup:
The right bottle is for ammonia and the upper tube for air. The tube can be lowered or raised to increase or decrease ammonia concentration as such it
act as a carburetor. then there is the catalyst tube and tree water absorption bottle. the last tube is for gas analysis, air is used in excess. The
reason for this is that when the nitrogen dioxide dissolve in water it make nitrogen monoxide, the monoxide is oxidized with the excess air in upper
of the absorption bottle and is ready for next absorption bottle.
 .
[Edited on 16-9-2012 by plante1999]
I never asked for this.
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liquidlightning
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That's pretty interesting, do you heat the catalyst tube?
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plante1999
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I do but only for starting an ammonia poor air combustion, then the catalyst glow dull red from the oxidation reaction, but I can also use ammonia
rich gas then the catalyst automatically become yellow-white, and then I lower the ammonia concentration. Ammonia rich gas mix make mostly nitrogen
but ammonia poor make a lot of nitrogen oxides.
I never asked for this.
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watson.fawkes
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I'll be interested to see what yields you're able to get without the higher temperatures and pressures that are used industrially.
Also, cobalt oxide has come into use as a catalyst in the Ostwald process. It was the result of a lot of effort to find a cheaper catalyst than
platinum.
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Lambda-Eyde
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Endimion, I think you are underestimating the power of Murphy's Law. And the health effects of SO<sub>3</sub>. From GC's thread:
| Quote: Originally posted by garage chemist |
If you choose to make SO3, please make yourself aware of the dangers of this substance first.
The warning "Extremely corrosive" does not really express the dangers appropriately. Oleum destroys many plastics, like PE and PP, that are completely
resistant to 98% H2SO4- only glass and fluoropolymers like PTFE are really safe.
The reaction of SO3 with water is explosively violent. SO3 must only be diluted with concentrated H2SO4!
SO3 and Oleum also create an extremely dense fog when handled in open air, due to reaction of gaseous SO3 with aerial moisture forming droplets of
H2SO4. If using a fume hood, be aware that all this thick fog will come out the exhaust! Most filters are incapable of precipitating H2SO4
fogs!
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And Fleaker's thread on the V<sub>2</sub>O<sub>5</sub>-catalyzed method:
| Quote: Originally posted by Fleaker | | [...] It also requires high temperatures and is hazardous as well. Sulfur trioxide is extremely aggressive at high temperatures and will
attack most all things organic. It forms thick, corrosive acid fogs that can blind or cause pulmonary edema. |
| Quote: Originally posted by Endimion17 |
It's not a nerve gas, for god sake. Pretty much anything can be done withoud a fume hood, if the apparatus is properly designed and assembled,
and if the excess gasses are being taken care of properly by series of tubes leading outside.
|
What will you do when one of the tubes begins to leak? A seal fails? A bubbler clogs? A flask breaks? Reaction gets out of hand? How will you transfer
SO<sub>3</sub>/oleum outside of a fume hood without breathing in a cloud of an extremely corrosive gas? A fume hood isn't a replacement
for good apparatus design and offgas handling, it's a failsafe for when (not if) things go wrong!
| Quote: Originally posted by Endimion17 | | Now, if someone is working with soda bottles and drinking glasses, it's easy to get poisoned. If one uses old fashioned corks and bungs, the poisoning
is less likely, but if one has a ground glass joint apparatus with Keck clips and joint lubrication, nothing happens. |
People working with soda bottles, drinking glasses, mason jars and caulk shouldn't be involved in amateur chemistry in the first place. If you're not
willing to spend money on real lab equipment you are trading away your safety. It's not about being able to afford it, it's about priorities.
| Quote: Originally posted by Endimion17 | | Sulphur trioxide can be readily condensed and solidified, and excess sulphur dioxide can leave the apparatus through a tube. |
Solid sulfur trioxide is still very volatile, producing mists of sulfuric acid.
I beg to differ. The syntheses of sulfur trioxide I have seen here on SM are among the most dangerous ones as well, together with preparation and
distillation of bromine and the phosphorus halides. Of course, I haven't read all the posts on the board and my memory may fail me, so please show me
something that you think deserves the title of "dangerous" more than SO<sub>3</sub>.
| Quote: Originally posted by watson.fawkes |
Also, cobalt oxide has come into use as a catalyst in the Ostwald process. It was the result of a lot of effort to find a cheaper catalyst than
platinum. |
Do you have any more info on this? Specifically, which cobalt oxide, any special way of preparing it, other potential uses as a catalyst etc.? I would
appreciate it.
And plante, your project sounds interesting. I expect a report in Prepublications when you're done, I bet it will be an interesting read. 
This just in: 95,5 % of the world population lives outside the USA
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cyanureeves
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interesting plante, now if you put glowing charcoals instead of that wool you got there then you could produce hydrogen cyanide couldn't you? how much
heat can those stoppers take? did you bend your own glass? are you saying that the platinum catalyst automatically glows and creates heat? or does it
just change colors in the presence of ammonia? do you need ammonium nitrate and sodium hydroxide to create the ammonia gas or will 20% plus ammonium
hydroxide work? how are you gonna keep the ammonia from pulling air towards it instead of pushing out?
[Edited on 17-9-2012 by cyanureeves]
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plante1999
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I know that carbon monoxide and ammonia on platinized asbestos wool form hydrogen cyanide, so I guess a good calculated ammonia/air ratio passed on
charcoal and then on platinized asbestos it should work too. Yes I have bend these myself, and the catalyst tube is made from a test tube with a cut
bottom. The stoppers can take about 200 degree Celsius but the gas mix cool down quite fast and I don'T have any problem with them. The platinum
become very hot because the oxidation of ammonia occur on its surface and oxidation reaction release energy. At the time I have used 30% ammonia and
it work very well. In fact I use an air pump on the right tube and ammonia cannot overcome the pressure of the pump. (The pump is not in the picture).
I never asked for this.
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watson.fawkes
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I did a fair bit of reading on this a few years ago, but all my notes are on a computer that's half-broken. I found it looking at
patent literature. One such (first patent link on search) is US3962138 Cobalt-oxide-based catalytic substances for the oxidation of ammonia. The keywords for searching are "cobalt oxide", "ammonia", and
"catalytic oxidation". One of the reasons I asked about yield was that a theme of this literature is the possibility of oxidizing ammonia all the way
to N2. This isn't just a theoretical catalyst; as of the time of my reading, the first production plant using this catalyst had gone live,
in Canada as I recall.
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blogfast25
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Interesting Plante. What's the source of ammonia?
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Endimion17
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| Quote: Originally posted by Lambda-Eyde | Endimion, I think you are underestimating the power of Murphy's Law. And the health effects of SO<sub>3</sub>.
What will you do when one of the tubes begins to leak? A seal fails? A bubbler clogs? A flask breaks? Reaction gets out of hand? How will you transfer
SO<sub>3</sub>/oleum outside of a fume hood without breathing in a cloud of an extremely corrosive gas? A fume hood isn't a replacement
for good apparatus design and offgas handling, it's a failsafe for when (not if) things go wrong! |
You can work by an open window with a fan. Why, for god sake, would synthesis of SO3 be limited with people who own a whole fume hood? It's a huge,
expensive overkill that can be avoided if one knows good alternatives. Anyone who doesn't shouldn't perform this at the first place! It's not like
anyone is going to make liters of it. We're talking about small apparatus here.
Tubes should be inspected before doing an experiment. Ground glass joint seals don't fail like corks. Bubblers don't clog because of nonprecipitating
reactions. Annealed flasks without cracks don't burst for no reason. SO3 synthesis can't get out of hand. We are not talking about reactions in liquid
medium stored in reaction vessels that need to be constantly stirred and cooled down. This is mixing of two gases over a catalyst and passing that
through a cooled vessel. There is no possibility of a runaway reaction here. You're exaggerating.
| Quote: | | People working with soda bottles, drinking glasses, mason jars and caulk shouldn't be involved in amateur chemistry in the first place. If you're not
willing to spend money on real lab equipment you are trading away your safety. It's not about being able to afford it, it's about priorities.
|
I don't agree. You can do amateur chemistry without expensive equipment, but you have to know the limits. If your equipment is based on bottles and
jars, pretty much every synthesis is unreachable, but you can nevertheless have a great time if you're just starting.
I don't know, maybe you were one of those rare, lucky kids who got a ground glass joint equipment as a kid. I didn't. It was before the era of online
markets and I was a poor little fuck. I had to work my way up, starting with shitty equipment and shitty experiments, gradually turning to cored corks
and rubber bungs. Today I own custom made ground glass joint equipment, tailored for my needs. Unfortunately, now I lack the time to do everything I
want, but that's a different story.
| Quote: | | Solid sulfur trioxide is still very volatile, producing mists of sulfuric acid. |
And it stays in the apparatus.
| Quote: | | I beg to differ. The syntheses of sulfur trioxide I have seen here on SM are among the most dangerous ones as well, together with preparation and
distillation of bromine and the phosphorus halides. Of course, I haven't read all the posts on the board and my memory may fail me, so please show me
something that you think deserves the title of "dangerous" more than SO<sub>3</sub>. |
I did all that without a fume hood without getting poisoned even slightly. I worked by an open window equipped with a fan, and I had few tubes going
outside. If I haven't chased away my cat, it would look at me sitting on the shelf, not giving a fuck about the traces of smell.
More dangerous? Isolation of alkali metals using electrolysis of their molten salts, synthesis of mercury salts, synthesis of all kinds of sensitive,
explosive compounds, synthesis of volatile organic compounds with high acute toxicity, just to name few.
Sulphur trioxide is a little cub if tamed in an apparatus. If a tiny plume of oleum escapes and drifts through the room, it's nothing compared to
getting mercury salt somewhere on your skin or floor, ready to be stepped on and carried into the kitchen.
Of course SO3 will turn into a cruel beast if you smash the apparatus, but hey... A car could kill you tomorrow even if you're on a sidewalk. Will
that make you walk around in a large bubblewrap sphere?
[Edited on 17-9-2012 by Endimion17]
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plante1999
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30% ammonia. I hop that I will be able to make some nitric acid soon. I will still have to increase the 40% acid to 68% to get a goo conc. acid since
40% is the maximum % I can get without pressure when dissolving the nitrogen oxides.
I never asked for this.
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watson.fawkes
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| Quote: Originally posted by Endimion17 | | SO3 synthesis can't get out of hand. We are not talking about reactions in liquid medium stored in reaction vessels that need to be constantly stirred
and cooled down. This is mixing of two gases over a catalyst and passing that through a cooled vessel. There is no possibility of a runaway reaction
here. |
True, but also a bit misleading on what some of the actual problems are.
First some physical data. The oxidation SO2 + 1/2 O2 --> SO3 is strongly exothermic, about 100 kJ / mol
SO3. The catalyst bed heats up in a contact process plant and requires explicit temperature control that includes cooling coils and dumping
waste heat. (Mind you, the hydration of SO3 is also exothermic, about 130 kJ / mol SO3. Contact process plants throw
off lots of process heat.) The reason for cooling the catalyst bed is that catalytic activity strongly decreases with temperature. The knee in the
curve (the curvature inflection point, and near the 50% yield point) is about 950 °C. The V2O5-based catalyst has to
become liquid on the surface of its carrier to become active; that happens around 680 - 700 °C. And then it's typical for the gas feed
temperature to rise from 700 °C to 900 °C in one pass through the catalyst bed.
The point is that this is a lot of ΔT, both within the apparatus itself as well as between the apparatus and the environment. Strain in
glass is directly proportional to the temperature gradient, and even well-constructed glassware will be at risk. Borosilicate glass just isn't best
suited for this environment. The recommended temperature range for borosilicate glass in extreme service is only 500 °C. It's softening point
is around 820 °C, which is possible to exceed in an exhaust gas stream, even assuming the catalyst bed is in ceramic. (Vycor would work for
this, incidentally, with only a bit of care. Fused quartz wouldn't even notice.)
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