| abstract |
Product gas (Gpro) is separated from material gas (Gmat)nby a PSA process utilizing a plurality of adsorption towersn(A-C) each loaded with an adsorbent. The separation of thenproduct gas (Gpro) is performed by repeating a cycle comprisingnan adsorption step, a decompression step, a desorption step,na cleaning step and a pressurization step. In the decompressionnstep, remaining gas (Grem) as cleaning gas is introduced fromnone adsorption tower (C) to another adsorption tower (B) . Thenamount of the remaining gas (Grem) introduced is 2 to 7 timesnthe volume of the adsorbent loaded in the adsorption tower (B)nas converted into volume at common temperature and undernatmospheric pressure. To remove both of carbon monoxide andncarbon dioxide from the material gas (Gmat) by a single kindnof adsorbent, use is made of zeolite having a faujasite structurenwith a Si/Al ratio lying in a range of 1 to 1.5 and anlithium-exchange ratio of no less than 95%. |