Patent ID: 8287762

Claim:
A method of operating a multi-stage ion transport membrane oxidation system comprising: (a) providing a multi-stage ion transport membrane oxidation system comprising at least a first membrane oxidation stage and a second membrane oxidation stage, wherein (a1) the first membrane oxidation stage comprises a reactant zone having a reactant feed gas inlet and an interstage reactant gas outlet, (a2) the second membrane oxidation stage comprises a reactant zone having an interstage reactant gas inlet in flow communication with the interstage reactant gas outlet of the first membrane oxidation stage and a product gas outlet, and (a3) an interstage feed gas inlet in flow communication with the reactant zone of the second membrane oxidation stage; (b) operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage by (b1) introducing a reactant feed gas into the reactant feed gas inlet of the first stage, (b2) withdrawing an interstage reactant gas from the interstage reactant gas outlet of the first stage and introducing the interstage reactant gas into the interstage reactant gas inlet of the second membrane oxidation stage, (b3) introducing a reactant interstage feed gas into the interstage feed gas inlet of the second membrane oxidation stage; and (b4) withdrawing a product gas stream from the product gas outlet of the second membrane oxidation stage; wherein the ion transport membrane oxidation system provides the product gas at a production capacity and a product quality; and (c) decreasing the production capacity while maintaining the product quality by decreasing the characteristic temperature of the first membrane oxidation stage to yield a reduction in oxygen flux through the first membrane oxidation stage, and keeping the characteristic temperature of the second membrane oxidation stage substantially unchanged to yield the product as having essentially identical methane feedstock conversion at the reduced production capacity.