Hydrogen production

[BrianM3265]

I'm new to SFN, greetings to all. I've been working on hydrogen generators using 316L stainless anodes and cathodes. The anodes oxidize away. Potassium hydroxide is added to distilled water. Will a coating of DuPont™ NAFION stop this? I have a vaccume pump hooked to a tank with electrodes and it seems more gas is produced with a vaccume of 25 reading on the guage. I thought that water would cold boil at a vaccume. At what reading? When it turns the water to gases is there away to pull out the oxygen leaving the hydrogen? Did I post these questions in the correct forum? Thanks, Brian (info@hydroasfuel.com)

[swansont]

In electrolysis you're going to form oxygen so I'd think you have to expect oxidation.

 

"25" without units doesn't mean anything to me; hydrogen does dissolve a little bit in water, so pulling a vacuum should reduce that (a transient effect, though).

[insane_alien]

i think the vacuum is just going to draw up more water vapour than increase efficiency of hydrogen production.

[krellor]

A few things. To help with the oxidation of your anodes I would suggest two possibilities. The first is carbon (graphite) rods. However, these may not be suitable due to their tendency to fall apart with high current density. The other option would be sintered nickel plates.

 

Either way, however you overcome the oxidation, once you have the gasses forming you shouldn't give them a chance to combine. The method for seperating them would be a pointless difficulty as you will already have your hands full just purifying them.

 

In the solution you described the hydrogen should form from the negative current, and oxygen from the positive. I would then build some sort of separator that would allow the hydrogen and oxygen to be routed to different chambers.

 

I am note sure where the vacuum factors in. If I have misunderstood your project, please elaborate and I will offer what advice I can.

[Melvin]

For anodes in electroysis, platinum is the way to go. If platinum is too costly, then graphite. Also, I've heard H2SO4 is a better electrolyte than KOH.

[BrianM3265]

I tried graphite anodes, they turn to powder. My gauge goes from 0-120 psi and 0-30 using the same 0. I was thinking that under a vacuum the water would evaporate. When I applied 12 volts at 7 amps my electrodes seem to produce more oxygen and hydrogen. Can't seem to pull more than a negative 25 lbs. I put gasoline under the same and it boils cold. With the positive giving off oxygen. Is there away the positive ions could be attracted to a positive pole thus separating the positive and negative ions , hydrogen and oxygen? Thanks Brian

[krellor]

I don't know that sulfuric acid will be a better electrolyte than KOH but either one would do the job. Also, the graphite rods may or may not work depnding on the current density at work here. As to getting the hydrogen and oxygen seperate, like I said, all you should need is a physical device to capture the gasses seperately. I have seen extremely complex devices that actually utilize the difference in molecule size to get the hydrogen and oxygen to go to different chambers. However, for a simplistic example, you could simply hold a test tube over the anodes to capture the gasses individually.

 

I did a quick google img search and found this:

 

http://www.miniscience.com/images/WaterElectrolisis.gif

 

That is a crude method. If you want me to elaborate on some of the more sophisicated physical devices I can do so and give you some links as well. Good luck.

[teji101]

what are the factors that could affect hydrogen generation rate?

[Klaynos]

what are the factors that could affect hydrogen generation rate?

 

Biggest one I'd imagine is the strength of it's bond... normally water seems to be used which IIRC is quite strongly bonded, but I think it nearly always is...

[thedarkshade]

yeah, like swansont said you can easily get hydrogen from water electrolysis. But also with electrolysis of some salts solution, some acids electrolysis , electrolysis of alkali peroxides.

 

Another method of getting hydrogen is also the reaction of acids with metals:

 

[ce]Zn + 2HCl -> ZnCl2 + H2[/ce]

 

Then there is also called the industrial method of getting hydrogen, which stand on the reaction of reddened carbon and water steam.

 

[ce]C + H2O -> CO + H2[/ce]

Then if you still continue the reaction in 500-600C in the presence of some enzymes you will get:

 

[ce]CO + H2 + 2H2O -> CO2 + 3H2[/ce]

 

Cheers,

Shade

[Mr Skeptic]

Just wondering, could you use lightning to do electrolysis? I suppose it would be impractical, but really cool.

[thedarkshade]

Too hard to control. Lightning sometimes can have tension of over 10000 and it comes so fast! It's too hard to control!

 

edit: 10000V ( i missed a V)

[John Cuthber]

You mised a few zeros too.

[thedarkshade]

Why don't you tell us the right number John! 10000V seems high enough to me!

[insane_alien]

a tiny lightning bolt(tinier than you would see in nature) is going to be on the order of 1 MV (1000000V) a big one could conceivably reach a few giga volts(1000000000 V)

 

really big ones could maybe reach 10GV.

 

10000V is below the static shocks you get from a TV.

 

you need about 3MV for every meter. so yours is about 3.3 mm real powerful that. i've had 10mm off my tv screen.

[thedarkshade]

really big ones could maybe reach 10GV.

And is there any way of storing that, so you could then somehow use it? Any techniques of "catching them" and using them for useful purposes?

[insane_alien]

its only about 500MJ per strike. not worth it. and considering the intermittent nature of lightning and the sparseness of it it would be impractical in not cost effective.

[thedarkshade]

Oh, I see!

Thank you IA!

[Jacques]

Not enzyme, but catalyst.

Enzyme would be detroyed at these temperature.

[thedarkshade]

Not enzyme, but catalyst.

Enzyme would be detroyed at these temperature.

Don't enzymes have the role of catalyst:rolleyes:

[insane_alien]

enzymes are biological catalysts yes. as such, they are extremely sensitive to conditions such as temperature, acidity, electric currents, solute content, and well, a lot of things ordinary catalysts like platinum can ignore. heck, enzymes can be destroyed by mechanical actions like stirring. in other words, for a chemical process like this you'll want an inorganic catalyst. platinum is used though other platinum group elements(gold, osmium, iridium, etc.) can be used.

[teji101]

i dont know the details of this theory (if it was investigated etc) but i heard that sand blasting the electrodes to make the surface rough and decreasing the space between the electrodes and applying a high frequency ac source across the electrodes would result to higher hydrogen+oxygen generation rate.

[thedarkshade]

enzymes are biological catalysts yes. as such, they are extremely sensitive to conditions such as temperature, acidity, electric currents, solute content, and well, a lot of things ordinary catalysts like platinum can ignore.

Yes IA!

Everyone knows that changes in body temperature have negative effects for the organism. And that's because the enzymes do not work anymore when the temperature changes or fluctuating (even worse). Enzymes are adopted to work in 36-37C and any change will only be harmful to the organism.

[jimt73]

Can anyone tell me what is in the mixture for the hydrogen generator and what is the ratio of ingredients. Thank you.

[Theophrastus]

Originally posted by thedarkshade

Enzymes are adopted to work in 36-37C and any change will only be harmful to the organism.

 

Actually, while it is true that most enzymes adapt to operation under physiological conditions, the trend of higher temperatures resulting in greater reaction rates does persist to an extent, as while temperatures above 50 degrees celsius are almost certainly destructive (though enzyme heat sensitivity does vary a fair bit), if the reaction rate is fast enough, you can bypass the basic "rules" of temperature tolerance, increasing the temperature substantially (here, we're talking a fair bit over 50, not 600 degrees, or something like that ), as, the faster the reaction rate, the shorter the heat exposure will be, and thus, the lesser likelihood of a temperature- induced breakdown of you enzymic catalyst.

 

But yeah, as Insane Alien said, for something like this an inorganic catalyst would be the prefered option. Either way, I myself greatly doubt using an enzyme, for something like this, would be feasible.

Edited August 5, 2009 by Theophrastus