Abstract: Process in conjunction with the production of oxygen (22), wherein incoming air (10, 16, 16a, 16b,) is brought to pass through a sorbent/zeolite structure (18), which comprises at least three zeolite units (50a–f) intermittently operated in a first stage comprising adsorption of nitrogen from the air and a second stage comprising desorption (20, 20a, 20b) of thus adsorbed nitrogen. At least two of the zeolite units are operated in the adsorption stage, the incoming air being brought to pass consecutively (53a) through the at least two zeolite units to form an increasing nitrogen gradient; and/or at least two units of the zeolite units are operated in the desorption stage, a pressure being released and/or a desorbing gas (22a, 22b) being brought to pass consecutively (53b) through the at least two zeolite units to form a decreasing nitrogen gradient in the zeolite units.