Process and composition for separation of oxygen from air using Pr-Ce as the carrier
AssigneeUnion Carbide Corporation
InventorJoseph Timothy Mullhaupt
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Abstract
Oxide solid solutions of praseodymium and cerium are useful as the oxygen carrier in a reversible cyclic oxidation-reduction process for separating oxygen from air. The adverse affects on redox rates of contaminants in the air, such as CO.sub.2 and/or H.sub.2 O are substantially eliminated by incorporating a surface dopant such as silver into the praseodymium-cerium oxide.
Claims11
A process for separating oxygen from an oxygen-containing gas mixture comprising the steps of:
- 1. oxidizing a reaction mass comprising a praseodymium-cerium oxide in a dissociated state containing about 33-92 mole % Pr by contacting it with said oxygen containing gas mixture thereby converting at least a portion of said reaction mass to a relatively more oxidized state,
- 2. separating the oxidized reaction mass from the oxygen-depleted gas mixture,
- 3. dissociating at least a portion of said oxidized reaction mass to form a relatively more reduced state of praseodymium-cerium oxide, thereby liberating oxygen, and
- 4. separating said liberated oxygen from said reduced state of praseodymium-cerium oxide.
A reaction mass comprising a non-stoichiometric oxide solid solution of praseodymium and cerium containing about 33-92 mole % Pr having the general formula:
- (Pr.sub.x Ce.sub.y)O.sub.z
- where:
- the sum of x and y equals 1.0, and z varies from 1.5 to 2.0
- and containing at least one surface dopant selected from the group consisting of silver, vanadium, manganese, copper, molybdenum, tungsten, platinum, thallium, lead and bismuth.
Dependencies are inferred from the claim text.