Air Products and Chemicals, Inc.

Thomas R White

Charles G Coe

Ronald Pierantozzi

John F Kirner

Shivaji Sircar

Rakesh Agrawal

Ravi Kumar

Donn Michael Herron

Eugene J Greskovich

The present invention relates to an improvement to cryogenic air separation processes which produce an ultra-high purity oxygen product and nitrogen and/or commercial purity oxygen products. In particular, the improvement of the present invention is characterized by removing a portion of liquid descending the distillation column system from the distillation section proximate to the location for withdrawing the oxygen-containing side-draw stream.

Production of ultra-high purity oxygen from cryogenic air separation

The present invention is directed to an at least binary exchanged X-zeolite having lithium and zinc cations in a ratio of preferably 5% to 40% zinc and 50% to 95% lithium, wherein the sum of the lithium and zinc ion exchange is at least 65% of the exchangeable ion content. Theses adsorbents are useful in a process for separating nitrogen from gas mixtures containing nitrogen and less strongly adsorbed components such as oxygen, hydrogen, argon or helium.

Zinc cation exchanged lithium X-zeolite for nitrogen adsorption

The present invention is directed to an at least binary exchanged X-zeolite having lithium and a divalent cation selected from the group consisting of cobalt, copper, chromium, iron, manganese, nickel and mixtures thereof in a ratio of preferably 5% to 50% of the divalent cation and 50% to 95% lithium. Theses adsorbents are useful in a process for separating nitrogen from gas mixtures containing nitrogen and less strongly adsorbed components such as oxygen, hydrogen, argon or helium.

Divalent cation exchanged lithium X-zeolite for nitrogen adsorption

The present invention is directed to a process for separating nitrogen from gas mixtures containing nitrogen and less strongly adsorbed components such as oxygen, hydrogen, argon or helium by use of an at least binary exchanged X-zeolite having lithium and a divalent cation selected from the group consisting of barium, cobalt, copper, chromium, iron, magnesium, manganese, nickel, zinc and mixtures thereof in a ratio of preferably 5% to 50% of the divalent cation and 50% to 95% lithium.

Nitrogen adsorption with a divalent cation exchanged lithium X-zeolite

The present invention is directed to a process for separating nitrogen from gas mixtures containing nitrogen and less strongly adsorbed components such as oxygen, hydrogen, argon or helium by use of an at least binary exchanged X-zeolite having lithium and calcium and/or strontium ions in ratio of preferably 5% to 50% calcium and/or strontium and 50% to 95% lithium.

Nitrogen adsorption with a Ca and/or Sr exchanged lithium X-zeolite

Argon is recovered from a gas stream comprising the same in admixture with oxygen and nitrogen, by a vacuum swing adsorption (VSA) process wherein the mixed gas is passed through an adsorbent bed having thermodynamic selectivity for adsorption of nitrogen and the unadsorbed portion then passed through a second adsorbent bed having kinetic selectivity for retaining oxygen. Both adsorbent beds are regenerated by vacuum desorption, applied to the first bed for a longer time period than that of the second bed. Further purification of the recovered argon may be carried out, if desired, by catalytic hydrogenation of residual oxygen therein. The mixed gas stream fed to the VSA unit may be that obtained from the crude argon column associated with a cryogenic air separation plant and the waste gas from the VSA unit may be recycled to the main column of the cryogenic air separation plant, thus enhancing argon recovery.

Argon purification

The water content of high purity nitrogen obtained by vacuum swing adsorptive fractionation of ambient air, is removed in a companion thermal swing drying system operated in association with the air fractionation system but at independent cycle time period, wherein water-laden nitrogen from the air fractionation system is passed through a desiccant bed of solid water-retaining adsorbent in said drying system while withdrawing dry nitrogen of high purity therefrom, and the adsorbed water is subsequently removed from said desiccant adsorbent by regeneration thereof with heated dry air effluent obtained in rinsing the air fractionating column with desorbed process nitrogen.

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Allentown, PA, United States of America

Thomas R White