Patent ID: 7629286
Filing Date: 2009-12-08
Classification: B01J,C07C,C07D

Abstract:
1. A fluid bed process for the production of maleic anhydride by the oxidation of a feed comprising C 4 hydrocarbons with molecular oxygen or an oxygen containing gas in a fluid bed reactor at a reactor temperature of about 325° C. to about 500° C. in the presence of an attrition resistant, fluidizable microspheroidal catalyst containing the mixed oxides of vanadium and phosphorus, wherein the maleic anhydride yield in said process decreases over time due to at least one of catalyst loss from the reactor or loss of phosphorus from the catalyst, wherein the catalyst is prepared by: (a) preparing a vanadium phosphorus mixed oxide containing catalyst precursor; (b) densifying the catalyst precursor; (c) comminuting the catalyst precursor to an average particle size less than about one micron in diameter; (d) forming fluidizable particles having a bulk density greater than or equal to 0.75 grams per cubic centimeter from the densified, comminuted catalyst precursor; and (e) calcining the fluidizable particles under fluidization-type conditions, wherein the maleic anhydride yield in said process is improved by the addition of a make-up catalyst to said fluid bed reactor, wherein said make-up catalyst contains an alkyl ester of orthophosphoric acid having the formula (RO) 3 P═O wherein R is hydrogen or C 1 to C 4 alkyl, at least one R being C 1 to C 4 alkyl in an amount sufficient to provide from about 0.000002 to about 1.0 pounds of alkyl ester of orthophosphoric acid per 100 pounds of total catalyst bed per day, and wherein said make-up catalyst is prepared by impregnating catalyst prepared in accordance with (a) through (e) with the alkyl ester of orthophosphoric acid.