Purification of Hydrogen from a Thermo-chemical Process using a Single-Column Pressure Swing Adsorption System with Compound Adsorbent.

Abstract

The thermo-chemical conversion of industrial sludge at atmospheric pressure and temperatures as a high as 750 degrees Celsius generates synthesis gas with the approximate per cent composition (volume basis): hydrogen, 45; carbon monoxide, 35; methane, 20. With these three gases as adsorbates, a single-bed pressure swing adsorption (PSA) system with activated carbon and molecular sieve 5 as adsorbents has been used to purify hydrogen to a per cent purity of 99.9999 %. This purity was the same for feed rates of 7 and 10 liters per minute at operating pressures of 45, 90 and 103 psi. The per cent recovery (productivity) varied from 22.70.6 at a pressure of 45 psi and a feed flow rate of 10 L/minute to 85.40.3 at a pressure of 103 psi for a feed flow rate of 10 L/minute. The maximum throughput (rate of hydrogen produced) was 3.840.01 when the pressure was 103 psi at a federate of 10 L/min. This work shows that with effective regeneration an alternation between two adsorbent beds can be used to separate methane and carbon monoxide from a mixture containing hydrogen with a volumetric concentration as low as 45 versus 60 volume per cent using PSA units with multiple beds.