an air separation process using pressure swing adsorption techniques , for providing high purity oxygen . two sections are employed one comprising beds of molecular sieve carbon and the other comprising beds of zeolite molecular sieve . air is fed to a first of the sections which provides an oxygen - rich gas stream as feedstock for the next section where further enrichment takes place . the zeolite sieve section serves to effect a separation as between oxygen and nitrogen while the carbon sieve section serves to effect a separation as between oxygen and argon and the processes performed at each section are integrated in such a manner as to minimize power consumption and make use of gas recycled from the second section to the first in addition to the flow of gas from the first section to the second .