SEPARATION OF GAS MIXTURES INCLUDING HYDROGEN

A process for separation of a gas mixture containing three components, e.g. a mixture comprising hydrogen, carbon monoxide and carbon dioxide produced by steam reforming a hydrocarbon, by pressure swing adsorption is disclosed. In one embodiment of the process, the gas mixture is sequentially passed through first and second adsorptive regions each of which adsorbs a second component more strongly than a first component but less strongly than a third component, a first fraction enriched in the first component is withdrawn from the downstream end of the second region, introduction of gas mixture to the first region is stopped and the second region is closed to the first region, a second fraction enriched in the second component is withdrawn first from the upstream end of the second adsorptive region while passing gas mixture enriched in the third component into the first region from its upstream end and then from the downstream end of the first region, and withdrawing a third fraction enriched in the third component from the upstream end of the first region. The separation process is also applicable to other gas mixtures such as a mixture of hydrogen, argon, methane and nitrogen commonly available as ammonia plant purge gas from which ammonia has been removed.