Sciencemadness Discussion Board

making palladium on carbon

alittlebitcrazy - 29-9-2017 at 16:11

i am reading about making palladium on carbon, the procedure doesn't seem complicated(at least in terms of the ingredients you need) at first but it looks like i need an "acid washed" activated carbon or to take a "regular" activated carbon and heated it with 10% nitric acid for 2 hours but i realy don't want to mess with nitric acid, not just because it is hard to make but also cause the ingredients for nitric acid are probably under strict regulations and can put anybody who buys them in somekind of blacklist and get marked by the police as potential terrorist.

so there is a way to make palladium on carbon without nitric acid? mybe another way to make "acid washed activated carbon" with some different kind of acid?

Vosoryx - 29-9-2017 at 16:51

I'm not sure how to answer your actual question, but Nitric acid synth is very easy, and the ingredients required to do so are very easily accessible, should you know where to look. (By chance, i'm actually distilling some HNO3 right now.)
I don't know how strict the conditions are where you live, but even if you can't find any nitrate salt/sulphuric acid based drain opener where you live, ordering them online should not raise any eyebrows by the cops.

For nitrate salts:
Some instant cold packs contain ammonium nitrate. If it says calcium ammonium nitrate, you have to recrystallize it.
Potassium nitrate is usually sold in home and garden stores as stump remover.
Sodium nitrate can occasionally be found in fertilizers. A rather niche source, but mine, is from aquaculture companies.
Even if you can't find them, searching online for instant cold packs on amazon reveals a box where the label clearly says "Contains ammonium nitrate"
The same goes for drain opener.

Though the shipping costs might be expensive, try to look it up anyway.

Sorry I can't help with the alternative routes for Pd/C, I'm just not a good enough chemist, but there are people who could tell you if that is possible on this site. Good luck!

Melgar - 30-9-2017 at 05:43

I'm pretty sure the main reason for using nitric acid is because it's a strong acidic oxidizer that won't leave sulfur, halides, or transition metals behind. You could try base piranha (aqueous ammonia and hydrogen peroxide, heated to about 70C) then wash a few times with an aqueous solution of a strong organic acid like formic acid or oxalic acid. The point is, you want the carbon partially oxidized so that it has sites on it that act as ligands for the palladium. Base piranha should do this, except there will be amide rather than acid groups left behind. So then you need an acid to cleave as many amides as possible, that won't leave behind some potentially reaction-poisoning element.

Morgan - 30-9-2017 at 12:13

I wonder if corona discharge would be of any use for the palladium-on-carbon process - corona discharge a method used on some plastics to make dyes adhere to them?
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S...

As an aside on dyes, yesterday at a farm type store, there was this funny blue dye I that's used to color ponds I happened across. How strange.
Ingredients: Acid Blue # 9 - 25.9 %, Inert and proprietary ingredients - 74.0 %
"This ingredient is safe for humans, fish, livestock, pets, birds, reptiles and nearby irrigation systems. Please refer to label for instructions prior to use."
http://www.agrisupply.com/crystal-blue-lake-and-pond-coloran...


alittlebitcrazy - 30-9-2017 at 12:59

Quote: Originally posted by Melgar  
I'm pretty sure the main reason for using nitric acid is because it's a strong acidic oxidizer that won't leave sulfur, halides, or transition metals behind. You could try base piranha (aqueous ammonia and hydrogen peroxide, heated to about 70C) then wash a few times with an aqueous solution of a strong organic acid like formic acid or oxalic acid. The point is, you want the carbon partially oxidized so that it has sites on it that act as ligands for the palladium. Base piranha should do this, except there will be amide rather than acid groups left behind. So then you need an acid to cleave as many amides as possible, that won't leave behind some potentially reaction-poisoning element.


the base piranha isn't the mixture used to bleach hair and making it blonde? or it is a more concentrated version?.

and for the organic acid, dose citric acid can be used?.

clearly_not_atara - 30-9-2017 at 13:10

Hair bleaching uses a mixture of persulfate and peroxide, usually with ammonium as a spectator ion. I think this might actually make singlet oxygen or something.

Base piranha uses ammonia as an actual base. This makes the peroxide more reactive, IIRC.

Ammonia is smelly and it's a gas. Ammonium is basically odorless and its salts are solids.

AJKOER - 30-9-2017 at 15:02

A poor (or wise) man's nitric acid substitute may be Al(NO3)3. Here are some Wikipedia comments (link: https://en.wikipedia.org/wiki/Aluminium_nitrate):

"Aluminium nitrate is a strong oxidizing agent. It is used in tanning leather, antiperspirants, corrosion inhibitors, extraction of uranium, petroleum refining, and as a nitrating agent."

"Aluminium nitrate may also be prepared a metathesis reaction between aluminium sulfate and a nitrate salt with a suitable cation such as barium, strontium, calcium, silver, or lead. e.g. Al2(SO4)3 + 3Ba(NO3)2 → 2Al(NO3)3 + 3BaSO4 "

I have been trying to prepare it recently. My intended reaction was:

Al2(SO4)3 + 6 KNO3 → 2 Al(NO3)3 + 3 K2SO4

where I would freeze out the K2SO4.

The problem I experienced was in preparing Al2(SO4)3, by the action of NaHSO4 on Al(OH)3. I have learned that I need a very fresh Al(OH)3 precipitate, otherwise only concentrated acids will react with old Al(OH)3.

[Edited on 30-9-2017 by AJKOER]

Assured Fish - 30-9-2017 at 16:27

This is an interesting topic, however i find it odd that the OP is unable to get his hands on nitric acid, its even more odd that the entire thread has wondered away from actually impregnating palladium onto carbon and has instead chosen to focus on the rather trivial aspect of cleaning the carbon of potential catalyst poisons.

@alittlebitcrazy If you are unable to prepare your own nitric acid due to a lack of glassware, then how the hell do you intend to use Pd/C for any hydrogenations?
Im not mocking the persuit of somewhat pointless (for lack of a better word) chemistry for the sake of alternatives.
Its just odd the way in which you have structured your post.

Again the idea is great, my skepticism is in whether the OP knows enough about chemistry to pull off such an experiment and then what the OP intends to do with the Pd/C.

Anyhow from what ive read of the only sources i have access to at present, the general route involves adding palladium chloride dissolved in HCl to acid washed activated carbon on an ice bath. Then or before adding the carbon, formaldehyde is then added.
This is then stirred at 0*C and then aqueous KOH or NaOH is added followed by heating and then of coarse filtration and washing.

What i want to know, is what is the mechanism thats going on here, what role does the formaldehyde take in this reaction and what bonds are formed in the final product e.g. is there a palladium carbon bond formed at all, or is it just a suspension of sorts?

https://en.wikipedia.org/wiki/Catalyst_poisoning
https://erowid.org/archive/rhodium/chemistry/pd-catalyst.faq...
https://en.wikipedia.org/wiki/Palladium_on_carbon

UC235 - 30-9-2017 at 19:23

Useful reference: http://orgsyn.org/Content/pdfs/procedures/cv3p0685.pdf

Melgar - 1-10-2017 at 03:59

Quote: Originally posted by alittlebitcrazy  
and for the organic acid, dose citric acid can be used?.

Actually, since you're adding PdCl2 anyway, you should be able to use hydrochloric acid. That would definitely be your best option.
Quote:
What i want to know, is what is the mechanism thats going on here, what role does the formaldehyde take in this reaction and what bonds are formed in the final product e.g. is there a palladium carbon bond formed at all, or is it just a suspension of sorts?

The formaldehyde is a reducing agent, that reduces the palladium to its metallic state. I've heard of formic acid being used for this too. It may also serve the purpose of binding the carbon particles together in loose clumps so that they're able to be filtered more easily.

The palladium is in its metallic state, but in very small particles. The acidic sites grab onto metal particles as they form, and prevent the particles from growing as large in size as they might have otherwise. The parallel that I'm familiar with is making gold nanoparticles, where citric acid plays a similar role:

https://en.wikipedia.org/wiki/Colloidal_gold

edit: The substance that limits the particle size is referred to as a "capping agent".

[Edited on 10/1/17 by Melgar]

alittlebitcrazy - 1-10-2017 at 11:17

Quote: Originally posted by Assured Fish  
This is an interesting topic, however i find it odd that the OP is unable to get his hands on nitric acid, its even more odd that the entire thread has wondered away from actually impregnating palladium onto carbon and has instead chosen to focus on the rather trivial aspect of cleaning the carbon of potential catalyst poisons.

@alittlebitcrazy If you are unable to prepare your own nitric acid due to a lack of glassware, then how the hell do you intend to use Pd/C for any hydrogenations?
Im not mocking the persuit of somewhat pointless (for lack of a better word) chemistry for the sake of alternatives.
Its just odd the way in which you have structured your post.

Again the idea is great, my skepticism is in whether the OP knows enough about chemistry to pull off such an experiment and then what the OP intends to do with the Pd/C.

Anyhow from what ive read of the only sources i have access to at present, the general route involves adding palladium chloride dissolved in HCl to acid washed activated carbon on an ice bath. Then or before adding the carbon, formaldehyde is then added.
This is then stirred at 0*C and then aqueous KOH or NaOH is added followed by heating and then of coarse filtration and washing.

What i want to know, is what is the mechanism thats going on here, what role does the formaldehyde take in this reaction and what bonds are formed in the final product e.g. is there a palladium carbon bond formed at all, or is it just a suspension of sorts?

https://en.wikipedia.org/wiki/Catalyst_poisoning
https://erowid.org/archive/rhodium/chemistry/pd-catalyst.faq...
https://en.wikipedia.org/wiki/Palladium_on_carbon


i am asking particulary about that "acid washed" cause i keep getting into this in every guide i readed about making Pd/C. and for the nitric acid, i don't have much knowledge in chemistry but i know in general(but didn't actualy tried it) that nitric acid can be made from nitrate salts and acids but i am affraid that gov/police in where i live(i won't say it here) are monitoring people who buy nitrates. i know it sounds paranoidic but this is also the main reason why i don't just buy Pd/C on the internet(i already found where to buy it and planned to do it before thinking about how it can look suspicious) ammonia solution and hydrogen peroxide are less suspicious.

but you right about me focusing only on this, i should also ask about the guide i found on making palladium on carbon(i think it was erowid site):
"Palladium on Carbon (5% Pd/C) [1]

Prepare a solution of 1.7 g of Palladium Chloride (or an equimolar amount of palladium chloride dihydrate, PdCl2*2H2O)
in 1.7 ml of concentrated hydrochloric acid and 20 ml of water by heating on a water bath for 2 hours or until solution is complete, and add this to a solution of 30 g of sodium acetate trihydrate (Note 1) in 200 ml of water contained in a 500 ml hydrogenation flask.
Add 20 g of acid washed activated charcoal (Note 2) and hydrogenate in an atmospheric hydrogenation apparatus until absorption ceases. Collect the catalyst on a buchner funnel and wash it with five 100 ml portions of water and suck dry as possible.
Dry the catalyst at room temperature over potassium hydroxide pellets or anhydrous calcium chloride in a vacuum dessicator. Powder the catalyst (approx 20 g yield) and store in a tightly stoppered glass bottle."

would it work?

alittlebitcrazy - 1-10-2017 at 11:42

Quote: Originally posted by Melgar  
Quote: Originally posted by alittlebitcrazy  
and for the organic acid, dose citric acid can be used?.

Actually, since you're adding PdCl2 anyway, you should be able to use hydrochloric acid. That would definitely be your best option.

[Edited on 10/1/17 by Melgar]

you mean washing the activated carbon with hydrochloric acid after washing it with base piranha right?. thanks for the help (:

[Edited on 1-10-2017 by alittlebitcrazy]

[Edited on 1-10-2017 by alittlebitcrazy]