Adsorptive separation of gases

Claim 1

In a process of adsorptively separating nitrogen from a gas mixture composed of at least nitrogen and oxygen by alternatingly adsorbing and desorbing oxygen on molecular-sieve coke contained in at least two vessels, of the type in which a stream of gas mixture is passed through a previously desorbed one of the vessels so that a stream of product gas consisting essentially of nitrogen issues from an outlet of said one vessel; the passage of the stream is terminated when the molecular-sieve coke in the one vessel has adsorbed oxygen to a predetermined extent; the inlet and outlet of said one vessel are connected with the inlet and outlet of the other desorbed vessel, so as to pressure-equalize said vessels; said vessels are disconnected from one another; and a stream of the gas mixture is passed through said other vessel so that a stream of the product gas begins to issue from the outlet of the other vessel, the improvement comprising diverting the stream of product gas from its normal path during a predetermined brief period starting at the initiation of its flow from said outlet of said other vessel so that an initial part of the product gas which contains an oxygen peak is not used, and thereafter a following part of the product gas which no longer contains the oxygen peak flows in its normal path to be used.