# Appearance of reduced Platinum Chloride?



## scwiers (Aug 1, 2008)

Just a thought experiment, only: say I had some PtCl(x) precipitate, and then attempt to reduce, on the assumption that "platinum chloride reduces at approx 6xx degrees C."

If I go about doing this in a flowerpot furnace, in a SiC crucible, will it reduce more or less to a powder, or does it kind of 'lump' together in little nuggets?

Curious, anyways.

Thanks again.


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## Lou (Aug 1, 2008)

It is kind of a drab red-black if you speak of PtCl2. Also, you don't want to heat that unless it is in a hydrogen atmosphere--otherwise it will volatilize away and deposit all over the place a thin platinum layer.


Edited: I was talking about PdCl2 being brown (which it is). PtCl2 is a blackish red.


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## lazylightning (Aug 1, 2008)

I'm considering the same idea now myself because I need to make something to reduce suspected Pt chloride in. So my source of hydrogen will be a reaction of Zn powder and dilute HCl (constantly added) channeled in through a long metal tube (thermal compatability with rubber hose from reaction bottle). Does my oven need to be hermetically sealed with hydrogen in it at slightly positive pressure? Or is it possible to simply channel a constant and abundant stream through the oven reactor chamber. I'm already designing a system that will give me a thin walled bentonite/ alumina chamber with the coils just outside of it and furthermore insulated with a thick layer made with the sawdust for airpockets. This will protect the coils from contact with the off-gases. However to make a hermitically sealed chamber capable of holding positive pressure hydrogen at high temperatures seems quite challenging to my freegan dumpster-diving for materials-budget.

Also, I may have to make a scourifier dish larger than those I've seen. Many dishes have a glass or quartz glaze and can handle up to 1300C. Will that do or do I need a porcelain dish with no glaze on it? Is the reduction dish material essential or can I make a dish of bentonite clay and not lose values or should I principally stick with the larger unglazed porcelain dishes that are available? It's not for potassium disulphate with sodium chloride melts of course.


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## Lou (Aug 1, 2008)

Bentonite sucks. You'd want a mullite or kaolin dish for high temperature work.

Unglazed is fine though.



As for hydrogen reduction, that's something you really can't attempt without the proper apparatus unless you want a fire/explosion.

Invest in a tube furnace, regulator and tank of H2 and some jointed quartz. I can post up what a hydrogen reduction system looks like on Monday (I'll take a photo of my setup in the laboratory).


Lou


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## Oz (Aug 1, 2008)

I would enjoy seeing that as well Lou. I have wondered how they did that 100 years ago w/o problems with fires. As for explosion hazards under normal conditions, no O2, no boom. But I wonder about vaporizing oxidizing salts with heat and hydrogen in a tube. It will be nice to see a proper set-up.


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## lazylightning (Aug 2, 2008)

Lou said:


> Bentonite sucks. You'd want a mullite or kaolin dish for high temperature work.
> 
> Unglazed is fine though.
> 
> ...



Thx! So I'll stick with the ready made dishes. So glazed is bad? I had a feeling that the catalytic plat-group elements might interact with the glaze at high temps. 

I made an atmosphere controlled baker/roaster that I pumped hydrogen in through a tube and it exited with the smoke and fumes through the exhaust tube into my fume hood. It was an old stainless pot with asbestos encasment. See photos. It worked at 475C, however I didn't know to use a dish and the bottom was cashed out during the second run and the molten material made it into my electric eye and it was cashed out too. My new electric eye only goes up to 350C though it's 1.5 kw instead of the first which was 1 kw and gave me 475C. I'm going to move onto more serious models now.

So I found a wide quartz tube leftover and can get a 50cm long and 20 cm wide w/ 4mmm wall peice for 130$. Not bad but still much for me right now. I have a sack of bentonite and a few jars of alumina. 30% alumina mix with bentonite is good for up to 1750C, much more than I need. I figure if I make the sleeve/tube from bentonite/alumina- to protect the coils from atmospheric contact with whats going on inside, it should be fine. 

Of course eventually I will save up for everything, including the thermostat. Just trying to get by with what I got now. 

So you mentioned a pressure regulator, does that mean that the hydrogen must be under slightly positive pressure during anealing? Simply channeling a constant and thick stream of hydrogen through the heating chamber will not do? I have a small tank but everyone only wants to fill big tanks and not the little one liter jobbies. So a regulator will be neccesary if I must keep it under some pressure during anealing. Then theres finding a way to seal it hermetically as can be done with a thing like hot hydrogen- which can even penetrate metal walls if given enough time. Large metal rings for door to tube sealing surfaces and asbesto-grafite powder seals with bolts to crank it tight? yikes....


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## lazylightning (Aug 2, 2008)

Is the chamber sealed up and pgm salts reduced under hydrogen in a sealed chamber to keep the plats from volatizing and escaping?


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## Lou (Aug 2, 2008)

FYI, I'm very certain that a 30% alumina balance bentonite mixture will not be serviceable at 1750*C. Bentonite is rife with fluxes.

You do not need to go to 1750C to reduce these metals. You barely need 600C (sometimes I go higher for an hour, then cool under hydrogen, then evacuate, then heat and cool in vacuo. This removes H2 gas out of the metal and makes it safer (smaller risk of fire from fine metal powder and H2)

Just wait a couple days and I'll show you my setup.

Lou


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## lazylightning (Aug 3, 2008)

Lou said:


> FYI, I'm very certain that a 30% alumina balance bentonite mixture will not be serviceable at 1750*C. Bentonite is rife with fluxes.
> 
> You do not need to go to 1750C to reduce these metals. You barely need 600C (sometimes I go higher for an hour, then cool under hydrogen, then evacuate, then heat and cool in vacuo. This removes H2 gas out of the metal and makes it safer (smaller risk of fire from fine metal powder and H2)
> 
> ...



Oh yeah, I understood that 600C to 800C would do fine. I just meant that I saw some bentonite with 30% alumina mix for sale and it was rated by the manufacturer as being able to go up to 1750C. I think my oven will have a maximum temp of about 1200C. The wiring in my apt. won't take more than 6kw and my three 1.8 kw "industrial" coils will bring it up nearly to that in wattage. I think that to make really high temps it would require special elements and a big old cable to the 380V main line in the corridor. 

I did see some scourifier dishes for pgm's from an outfit in the Ural mountains, the dishes/cups(all sizes) are made from 99% alumina and are guaranteed to work well at 1750C. They make some with Ir or Pt linings but warn that Ir loses it's resistance qualities dramatically in acidic environments at high temperatures. They make a zirconium oxide model that they guarantee to work fine up to 2500C. :O 

My main concern still is the question of pressure. If it has to be sealed up. Can I simply run hydrogen through it without sealing it and after it cools pump air through it for an extended period to flush the hydrogen? Or does the hydrogen have to be kept constantly at some kind of pressure and does it need to be sealed up to keep values from floating away? I do have a vacuum pump though and am prepared for everything -morally ....
The pressure reg and tank will be problematic though.

Can't wait to see the pics. Like they say, a picture tells a thousand words.


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