Separating H2 from O2 after electrolysis

[Jdo300]

TL;DR

Looking for ideas to separate H2 from O2 after electrolysis (in a system where they are not naturally separated in the process.

During typical electrolysis, I understand that the Hydrogen and Oxygen can be separated by isolating the positive and negative plates of the system into separate chambers to capture the gas. But in the case of electrolyzers that create a combined gas output (HHO/hydroxy gas/browns gas, etc.) The H2 and O2 are mixed together in the output.

Are there any standard processes for separating these two gasses from each other assuming they are already combined after electrolysis? Googling terms like "Separating H2 from O2" or "Filtering hydrogen from Oxygen" just turns up results on water electrolysis.

 

[jrmichler]

The easiest way would be to chemically combine the H$_2$ and O$_2$ into H$_2$O, then electrolyze the H$_2$O in an apparatus where the two gases are separated. A harder way would be use high speed centrifuges similar to those used to separate uranium isotopes. There are even harder ways, which you can find by searching older methods of separating uranium isotopes.

 

[Baluncore]

Simply cool the mixture to below 90 K, (−183 °C). The oxygen will condense to a liquid at 90 K. The hydrogen remains as a gas down to 20 K. Use a counter-flow heat exchanger to improve the economy.

You might consider a molecular sieve such as a platinum metal shim. Small H2 molecules will pass through, the bigger O2 will be blocked.
https://www.nature.com/articles/s41467-020-20628-9