SAFE Syngas Associates FE LLC

'Pressure swing adsorption ("PSA")' and other 'dry bed' systems is used to adsorb CO2 and/or H2S physically.

In the case of synthesis gases, PSA is used to recover CO2 from upstream, high-pressure raw syngas streams or low-pressure off-gas streams generated by steam reforming or gasification processes. PSA processes are supplied by Linde, UOP, Air Liquide and so on. In many cases, it is said that PSA is a more cost-effective alternative to conventional washing systems due to its lower investment and operating costs. Except for Linde, however, CO2 is not forcused as separated gas so atractively but mainly H2 recovery.

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As to 'dry bed' process, iron sponge and molecular sieve are used. Iron sponge is just for removal of small amount of H2S and it is only possible to conduct partial regeneration. Molecular sieve is attractive for DeCO2 as well and can be remove H2S selectively under the presence of CO2 when CO2 in the product is very low and CO2 in feed is 1.5 vol% or less. Activated carbon is used mainly as guard bed for removal of small amount of H2S.