Sciencemadness Discussion Board

Makeshift Pt Catalyst?

Meltonium - 20-11-2016 at 06:02

Opening up an old computer hard drive will reveal several shiny discs. These discs are plated in a small amount of very pure platinum (no more than a few microns) Could this be used as a makeshift platinum catalyst?

MeshPL - 20-11-2016 at 09:50

If you are sure that this is platinum... potentialy yes. Depends on what do you want to use it for. It should be able to catalyse self ignition of butane in air while hot or allow you to make hydrogen electrochemical cell if properly designed and if the layer is fully conductive. But don't even try hydrogenation with such "platinum", it will never work.

But again, are you sure this is a coating of pure platinum?

Meltonium - 20-11-2016 at 12:00

Quote: Originally posted by MeshPL  

But again, are you sure this is a coating of pure platinum?


Not 100% sure. I've been told they are coated with platinum or sometimes ruthenium but I'm not sure whether or not it's alloyed with something.

wg48 - 20-11-2016 at 16:48

I was curious as to how much platinium is in a hard drive disk.

The quote below suggests the disk is coated with an alloy of platinium that is only 0.03 microns thick ie 2.2mg of Pt or 10 cents/7p worth. I was not able to confirm the thickness.

"It's taken me just about forever, but I've finally found some way to answer the simple question "How much platinum is in these hard drive platters showing up on Ebay for salvage?" "The Chemistry of Computing" over at extremetech.com (article2/0,2845,1946290,00.asp) has all the facts: surface layer of Co-Cr-Pt alloy is 40-50% platinum, and the layer is ~30 nm thick. I don't have a hard drive platter in front of me, so let's just forget about the hole in the middle for a moment, so one platter from a 3.5" disk is 3.14*(3.5/2)^2=10.4 sq inches or 67.2 cm^2 ... times the 30 nm thickness (3x10^-6 cm) is 2.0x10-4 cm^3, times the (optimistic) 50% Pd, times the density of Pt (21.45 g/cm^3) and I estimate one platter has at most 2.2 mg Pt. As of 08/29/2008, the platinum spot price was 1470.00 USD per troy ounce, or more usefully, 4.73 cents per miligram"

Full article at Scrap Metal Forum: http://www.scrapmetalforum.com/general-electronics-recycling...

Meltonium - 20-11-2016 at 18:05

So... in other words it would be unusable for a catalyst? I just have some lying around and was looking for something to use them for other than a mirror.

MeshPL - 21-11-2016 at 01:05

You can try using this disc as a catalyst. But it depends what do you want do do with it. As those discs contain glass I'm not sure, what would be a good test for their catalytical proprieties, they may crack at high temperature I suppose. You can try to break one in small pieces, heat them with a bloiwtorch, than put the torch out and open the valve again, so that the gas is released at the hot pieces. If the gas ignites, that is due to platinum catalysing the initial combustion, probably. Is the surface of the disk fully conductive? Than you can attemp to make a hydrogen fuel cell. Although the cathode may be problematric, as during the charging,m plating, which contains basic metals may be oxidised.

zed - 21-11-2016 at 18:57

Now, if it were the case that it were Ruthenium, you might be able to tell by the color of the disk. Ruthenium has a dark sheen to it. Black, you might say. Makes stunning jewelry, but you won't mistake it for Platinum. Ruthenium isn't Silver-y in appearance.

"So", you might say...."Maybe I'll play with that Ruthenium"

Could be fun, but keep in mind...Salts of Ruthenium may be deadly toxic. Like, Osmium Tetroxide toxic.

https://www.google.com/search?q=ruthenium+jewelry&tbm=is...

[Edited on 22-11-2016 by zed]