Process for the purification of nitric oxide
AssigneeThe BOC Group, Inc.
InventorsLien-Lung Sheu, Ramakrishnan Ramachandran, Theodore R. Galica
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Abstract
A gas mixture comprised of nitric oxide and, optionally an inert gas, and containing small amounts of nitrogen dioxide, and perhaps moisture and sulfur dioxide, is purified by passing the gas stream through a bed of zeolite having a silica to alumina ratio not greater than about 200. The concentration of nitrogen dioxide, sulfur dioxide and moisture in the gas stream are reduced to about 1 ppm or less as the gas mixture passes through the bed of zeolite.
Claims25
A process for purifying a substantially oxygen-free nitric oxide gas stream containing nitrogen dioxide at a nitric oxide to nitrogen dioxide molar ratio of at least about 5:1 comprising passing said gas stream through a bed of particulate zeolite having a silica to alumina ratio of not greater than about 200:1, thereby adsorbing nitrogen dioxide and producing a nonadsorbed nitric oxide gaseous product containing not more than about 5 ppm nitrogen dioxide.
A process for preparing an inert gas-nitric oxide gaseous product containing about 5 to about 5000 ppm of nitric oxide and not more than about 5 ppm of nitrogen dioxide comprising passing a substantially oxygen-free nitric oxide gas stream containing nitrogen dioxide at a concentration such that the molar ratio of nitric oxide to nitrogen dioxide is at least about 5:1 through a bed of particulate zeolite selected from type 5A zeolite, type 4A zeolite, type 13X zeolite and mixtures of these, thereby adsorbing nitrogen dioxide from said stream, and diluting the nitrogen dioxide-depleted stream with an inert gas sufficiently to produce said gaseous product.
A process for preparing an inert gas-nitric oxide gaseous product containing not more than about 5 ppm of nitrogen dioxide comprising blending a substantially oxygen-free nitric oxide gas stream containing nitrogen dioxide at a concentration such that the molar ratio of nitric oxide to nitrogen dioxide in said gas stream is at least about 5:1 with sufficient inert gas to reduce the concentration of nitric oxide in the resulting gas mixture to about 5 to about 5000 ppm, and passing said gas mixture through a bed of particulate zeolite having a silica to alumina ratio of not greater than 200:1.
Dependencies are inferred from the claim text.