| 摘要 |
Purification of a hydrogen-based gas mixture containing impurities such as carbon monoxide, nitrogen and methane is effected by contacting the gaseous mixture with a zeolite adsorbent which is a shaped product comprised of at least 95%, as determined on the basis of the moisture equilibrium adsorption value, of a low-silica type X zeolite having a SiO2/Al2O3 molar ratio of 1.9 to 2.1. The zeolite adsorbent is preferably ion-exchanged with lithium and/or calcium. The zeolite adsorbent is preferably prepared by a process including a step of contacting with a caustic solution a calcined product of a mixture of a low-silica type X zeolite and kaolin clay whereby the kaolin clay is converted to a low-silica type X zeolite.
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