Sciencemadness Discussion Board

Does anyone have a homemade H2 generator or advice on makong a simple setup?

Tkuze - 18-6-2019 at 20:45

I was wondering if anyone has a homemade hydrogen gas generator apparatus or would be willing to offer advice on building one. Please post pictures if you have any
Thanks

Keras - 18-6-2019 at 21:18

Drip sodium hydroxide over aluminium tinfoil.
If you want dry hydrogen, pipe the gas through a bubbler filled with concentrated sulphuric acid.
This method is better than hydrochloric acid over zinc because the reactants are cheaper and more OTC (pure zinc is not that easy to come by).

Corrosive Joeseph - 18-6-2019 at 21:18

Aluminum foil and lye..........? The following is taken from somewhere else.
Quote:


H2 gas generator using a Büchner flask

Connect Büchner flask via the hose barb to the reduction flask.

Place 2 M NaOH solution in Büchner flask, and Al and stopper with rubber bung. Fix rubber bung with wire to ensure H2 pressure is not lost.

Charge the reduction flask with Pd/C, or Pt/C catalyst, solvent, and compound.

Vacuum all air from the reduction flask and Büchner flask, allowing H2 gas to displace ALL AIR from both flasks.

Alternatively, an inert gas such as N2, or Ar can be used.




Reaction of aluminium metal and alkali -

Sodium aluminate is also formed by the action of sodium hydroxide on elemental aluminium which is an amphoteric metal. The reaction is highly exothermic once established and is accompanied by the rapid evolution of hydrogen gas. The reaction is sometimes written as:

2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2
however the species produced in solution is likely to contain the [Al(OH)4]− ion or perhaps the [Al(H2O)2(OH)4]− ion.

This reaction has been proposed as a potential source of fuel for hydrogen powered cars.
https://en.wikipedia.org/wiki/Sodium_aluminate



/CJ

elementcollector1 - 18-6-2019 at 21:19

Homemade H2 generators aren't terribly hard unless you want high output. A simple concept is electrolysis of water with an ionic salt that's difficult to actually split (such as a sulfate) but still renders the solution conductive.

Design is the same as any other gas generator design - a sealed container with gas outlets above the cathode (negative electrode, produces hydrogen) and anode (positive electrode, produces oxygen). If you want to get fancy, you could add a water intake to replenish lost solution, as well as some means of storage for the produced gases - common amateur setups are balloons or inverted beakers/flasks over water.

For more specifics, I'd have to know more about your intended use for the hydrogen. Do you want to store it, use it, or combine it with something else?

[Edited on 6/19/2019 by elementcollector1]

Tkuze - 19-6-2019 at 04:05

Thanks for the great advice. I have constructed hydrogen generators using batteries and bicarbonate solution for undergraduate students to use in the gen chem lab I was prepping as a stockroom worker. My intended purpose or design is a simple voltaic hydrogen generator for filling up a baloon or something similar when needed for performing hydrogenation reactions. Essentially some self containee plastic unit wirh plates and outlet which will somehow generate enough pressure to slowly fill a balloon with hydrogen using a battery or any current. Just a little self contained system sort of thing

Keras - 19-6-2019 at 05:18

You can very much fill a baloon with a NaOH/Al chemical generator. Nilered has a video where he demonstrates that, but I can't remember which one. He then uses his hydrogen baloon to reduce some compound using Pd/C catalyser.

Tkuze - 19-6-2019 at 09:42

Awesome! That does seem like the easiest and quickest way. Thanks for the advice and reference!

unionised - 19-6-2019 at 10:12

Depending on what rate you want, this sort of think might be neater.

https://www.youtube.com/watch?v=smlG6oeXkQo

Sulaiman - 19-6-2019 at 10:14

Electrolysis works but is slow (unless you have a large purpose built cell)
Al + NaOH(aq.) works well - but Al cans have a (cold)NaOH-proof coating.*
(Mg or Zn) + 1M H2SO4 is convenient.
diy storage is risky.


P.S. * so beware of thermal runaway

[Edited on 19-6-2019 by Sulaiman]

lordcookies24 - 19-6-2019 at 13:26

If you want one that you can very easily reuse I could suggest an electrolysis tank.

Twospoons - 19-6-2019 at 15:06

I've used NaOH + Al to make floaty balloons for my kids - best was to use chunks of AL to keep the rate under control. Thermal runaway is a problem, as is the fine mist of NaOH solution that comes off with the H2.
Later I built a big electrolysis unit (4 cells using SS plates and NaOH as an electrolyte). Pressurizing a balloon was not simple as you have to control for the O2 side as well (at half the H2 rate), and keeping them balanced was tricky. At one point I lost the balloon off one side (it slipped) and the pressure from the other side forced electrolyte out of the cell and all over me and my lab.
As for the speed of H2 production, the electrolyser was able to sustain a flame on the end of a 20mm pipe, just as fast as a controlled NaOH+Al bottle.

In short, both methods have pros and cons.

DavidJR - 19-6-2019 at 15:33

Hell, you could even go old school and get a Kipp apparatus...

Tkuze - 19-6-2019 at 15:51

Thank you all for the great advice and various experiences!! I have a huge pool of knowledges to dig into! I really appreciate all your suggestions!