Vapor phase catalytic oxidation of N-butane to maleic anhydride incorporating in situ catalyst calcination/activation

摘要

An improved process for selective vapor phase oxidation of n-butane to maleic anhydride involving the use of a recirculating solids reactor having a reaction zone and a catalyst regeneration zone wherein n-butane is converted to maleic acid in the reaction zone by use of a vanadium/phosphorous oxide (V/P/O) catalyst in oxidized form and the reduced vanadium/phosphorous oxide catalyst is regenerated by contact with oxygen in the regeneration zone. Replenishment of the inherent catalyst losses associated with the catalyst recycling process is accomplished by adding to the catalyst in the regeneration zone vanadium/phosphorous oxide catalyst precursor at a rate of addition that effectuates in situ calcination and activation of the vanadium/phosphorous oxide catalyst precursor while simultaneously maintaining the desired operating temperature of the n-butane to maleic anhydride conversion reaction. Such a process is useful in maintaining the high operating capacity of the reactor over an extended period of time.