PSA for hydrogen purification work by pressurizing a vessel containing adsorbent.  The process relies on the fact that different gasses adsorb at different pressures and temperatures.  So for the case of hydrogen at room temperature very little of the gas molecules will be adsorbed, whilst water, CO2, CO and H2S etc are readily adsorbed, thus purifying the gas.  when the pressure is reduced below a certain limit the contaminants desorb back in to the gas stream, leaving the adsorbent ready for the next batch.  by using a series of materials in different vessels it is possible to reach reasonably high purity.

The PSA system has two activated carbon beds connected in parallel. While one bed is operating and adsorbing the gas (like CO2 or H2 gas), the other bed undergoes desorption by heating with steam (this is the saturated bed). The adsorption phase favors high pressure and the desorption phase favors lower pressure. Hence the name pressure swing absorption (PSA).

Hope this helps answer your question.

I teach the PSA technology in my separation & purification course at Yale University.

Khalil, Y.F. (Fall 2016). Separation & Purification. Lecture notes, CENG-412, School of Engineering & Applied Science (SEAS), Yale University, New Haven, CT 06520, USA.

Professor Yehia Khalil

Yale University

USA

There is no heating required to regenerate a commercial H2 PSA.  During the adsorption phase the H2 rich gas passes over the adsorbent and adsorbs essentially everything that is not H2.  At the end of the cycle the  valves switch so that feed stream  goes to recently "regenerated" PSA vessel.  The system minimize loss of H2 by depressuring in several steps.  In this way most of the H2 that was left in the vessel is used to repressure vesels that have been regenerated a low pressure.  he adsorption vessel typical operates around 300 PSIG (20 barg) and the .final purge of essentially all non H2 to fuel occurs at around 15 PSIG (1 barg).  State of the art multi-bed PSA's will recover approximately  90% of the H2 at 99.99+% purity.  I have attached a document from Linde discussing their commercial PSA offering  Almost all new Steam Methane reforming based H2 plants built since the late 80s use PSA to recover H2. Feel free to contact me directly at [email protected] if you need addition information about PSA units and/or commercial scale H2 Management

Diogo, 

I have attached a paper I found re DME from syngas.  Is this process similar to the process you are studying- with  target H2/(H2+CO) =1?

If so I would like to suggest that you consider either membrane H2 removal or solvent based CO2 removal and recycle (amine or potassium carbonate based CO2 removal) with CO2 recycle to the either the steam methane reformer or to a water gas shift reactor to achieve proper ratio.  PSA would probably not be an appropriate choice for a commercial unit because the CO product would be at very low pressure and compression costs would be very large, Can you share the proposed process flow scheme that you are considering?