Check with Air Products -

"PRISM® SEPARATORS operating in ammonia purge recovery systems can recover up to 95% of the available hydrogen. This recovered hydrogen can be made available at purities in excess of 98% either for recycle to synthesis loop or for use in other processes."

http://www.airproducts.com/~/media/Files/PDF/products/supply-options/prism-membrane/en-PRISM-SE-process-gas-membrane-separator.pdf

Dear Lauren Scott

Thanks for your answer. According to PRISM “PRISM separators will permeate the oxygen and hydrogen in the same stream” so it can’t be use to separate hydrogen from oxygen.

Have you considered a Pressure Swing Absorption (PSA) system?

"Hydrogen separation. The main application for PSA in a refinery is the recovery and purification of H2 from gas streams, such as synthesis gases from steam reforming, POX or gasification, as well as from refinery offgases. The H2 product can be obtained at high purity — up to 99.9999% — and high recovery rates of up to 90%. "

https://www.chemengonline.com/psa-technology-beyond-hydrogen-purification/

Thanks Lauren Scott and Muzammil Iqbal

I will study the Pressure Swing Absorption process, and try to find if it is possible to separate hydrogen and oxygen completely.

There are commercially available polymeric membranes with quite high H2/O2 selectivity but my more basic question is whether you have considered safety aspects? Are you below the moc for H2 (5% O2). As you recover H2, are you going to exceed this limit? Also remember the wide flammability range (LEL-UEL) for H2.

Hello,

Have you tried with palladium membrane separators?

https://www.hysep.com/

Ibrahim Mohammad You wrote: I " will study the Pressure Swing Absorption process, and try to find if it is possible to separate hydrogen and oxygen completely." I hope you aren't actually mixing H2 and O2. That is not a safe mixture.

Cryogenic separation will work well. But it is dangerous to mix H2 and O2.

Thanks Rick Manner

I have checked Pressure Swing Absorption (PSA) process, some claim to purify hydrogen, but from PSA principle oxygen have weak absorption so it looks difficult to separate.

I don’t have plan to mix hydrogen/oxygen but in some water splitting cases, we got mixture of hydrogen/oxygen, like from cathodic discharge electrolysis. I am thinking for its separation.

Molecular sieve 5A is specifically designed for Pressure Swing Absorption (PSA) hydrogen purification.

"The final stage in purifying hydrogen is to use a Pressure Swing Adsorption (PSA) process. The PSA process will use either a 5A molecular sieve, which is usually used to create high purity hydrogen or a 13X molecular sieve to adsorb larger hydrocarbons and other impurities if they are there."

5A Molecular Sieve’s Role In Hydrogen Production

http://hengyeusa.com/community/5a-molecular-sieves-role-in-hydrogen-production

Here is a paper on the subject -

Comparative Study for Adsorption of Hydrogen-Methane Mixtures on Activated Carbon and 5A Molecular Sieve

http://www.scielo.br/pdf/bjce/v35n2/1678-4383-bjce-35-02-0795.pdf

From the Linde Engineering web site -

Hydrogen recovery and purification

Linde Engineering has the expertise and experience to deliver tailor-made hydrogen recovery plants offering outstanding quality, reliability and availability.

Our proven high-performance pressure swing adsorption (PSA) plants can be used to recover and purify hydrogen from hydrogen-rich streams such as synthesis gases resulting from steam reforming and gasification processes or off-gases from refinery and petrochemical plants.

We support the full spectrum of capacities from small plants producing a few hundred Nm³/h to large-scale plants that produce more than 400,000 Nm³/h. Our proven technology delivers the highest recovery rates, and the resulting hydrogen gas meets all purity requirements up to 99.9999 mol-%.

https://www.linde-engineering.com/en/process_plants/adsorption-and-membrane-plants/hydrogen_recovery_and_purification/index.html