Purification/Collection of Hydrogen: from a H2-Air mixed stream

[testing]

Hello everybody! I am currently finding a suitable process to separate hydrogen from a H2-Air mixture stream (in small scale). I would like to ask for some opinion or suggestions for the following situation:

I have a mixture stream of hydrogen and air, i.e., it is composed of H2, O2, N2, and water vapor. Attachment 1 (H2-Air stream illustration.jpg) is a simple illustration about the situation. Some system information are given below:

Hydrogen production rate: 900 L/hr

System daily operating hours: 10 hr/day

The system described above is in small scale. The daily production can only theoretically fill 1.67 tank of cylinder (40L, 135bar H2 cylinder). I was given a task to utilize these hydrogen. The budget is around $20,000 USD. I have got some ideas but each of them is having the following problems:

 

1. Directly collection of the stream by pressurization and high pressure cylinder storage

1A. The expected H2 purity would be low as it is mixed with O2 and N2. Is this kind of hydrogen useful in any kind of industrial application? (e.g. Some kinds of fuel cell that do not require high H2 purity like molten carbonate fuel cells (MCFC's) and solid oxide fuel cells (SOFC's))

1B. Are there any simple methods to increase the purity of H2 before pressurizing it?

 

2. Extraction/Purification of Hydrogen in the stream: Zeollite (molecular sieve) is famous in H2 storage, but I am not quite familiar with this material. I would like to ask:

2A. Is zeolite a suitable mean in collecting those hydrogen?

2B. Which type of zeolite is able to separate H2 from O2 and N2?

2C. How can used zeolite be regenerated? How should I design this purification system? (A small scale system, maybe several equipments/piping occupying a space smaller than 2m x 2m x2m)

2D. Will it be better if I separate those gases by some extra devices in addition to zeolite (say, place some water absorbing agents before zeolite to remove the water content)?

Attachment 2 (proposed design) is my draft proposed design.

 

3. Combination of idea 1 and 2: hydrogen extraction by zeolite followed by filling of pressurized tank

3A. If idea 2 does work, is it very common to directly utilize the released hydrogen during regeneration? How?

3B. If the released H2 must be stored by some ways, is it again by pressurization? Or others?

 

4. Any kinds of other suggestion

 

Thank you very much for reading my passage Any answers are welcomed~ ~ ~

[Wilmot McCutchen]

H2 has a molecular weight (molar mass) of only 2 g/mol, whereas N2 and O2 are 28 and 32, respectively. So centrifugal gas separation might work. A vortex tube (http://en.wikipedia.org/wiki/Vortex_tube) might be enough for your needs. The hydrogen plus water vapor would come out the cool end and the O2 and N2 would go out the hot end, continuously, as the mixture is injected. See also http://www.scienceforums.net/topic/59629-mechanical-gas-separation-for-post-combustion-co2-capture/