Separating H2 from O2 after electrolysis

In summary, there are various methods for separating hydrogen and oxygen gases after they have been combined through electrolysis. These include chemically combining them into water and then re-electrolyzing, using high speed centrifuges, cooling the mixture to below 90 K, and using a molecular sieve. However, the most effective and efficient method would be to use a counter-flow heat exchanger, as suggested in a recent study published in Nature.
  • #1
Jdo300
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TL;DR Summary
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.
 
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  • #2
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.
 
  • #3
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
 
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Related to Separating H2 from O2 after electrolysis

1. How does electrolysis separate H2 from O2?

Electrolysis is a process that uses an electrical current to break down a compound into its individual elements. In the case of separating H2 from O2, a direct current is passed through water, causing the water molecules to split into hydrogen ions (H+) and hydroxide ions (OH-). The hydrogen ions are then attracted to the negative electrode (cathode) and the oxygen ions are attracted to the positive electrode (anode), thus separating the H2 and O2.

2. What materials are needed for electrolysis to separate H2 from O2?

The materials needed for electrolysis to separate H2 from O2 include a direct current power source, two electrodes (one positive and one negative), a container of water, and a conductive material such as a salt or acid to increase the conductivity of the water.

3. How do you know when the H2 and O2 have been separated?

During electrolysis, bubbles will form at the electrodes. The bubbles formed at the negative electrode will be hydrogen gas (H2) and the bubbles formed at the positive electrode will be oxygen gas (O2). Once the process is complete, the gases can be collected and separated.

4. What are the uses of separated H2 and O2?

Separated H2 and O2 have various uses in different industries. Hydrogen gas is commonly used in fuel cells to produce electricity, in the production of ammonia for fertilizer, and in the production of methanol. Oxygen gas is used in medical applications, such as oxygen therapy, and in the production of steel and other metals.

5. Can electrolysis be used to separate other compounds?

Yes, electrolysis can be used to separate other compounds besides water. It can be used to separate compounds such as sodium chloride (salt) into sodium and chlorine, or to separate copper sulfate into copper and sulfur. The specific materials and conditions needed for electrolysis will vary depending on the compound being separated.

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