E.i. Dupont De Nemours and Company

Harold S Horowitz

Rashmikant M Contractor

Arthur W Sleight

Stephan James McLain

Joe Douglas Druliner

Donald I Garnett

Eugene Michael McCarron

John Donal Sullivan

Gregg Mason Sisler

Gregory Scott Patience

Vanadyl pyrophosphate oxidation catalyst precursors comprise vanadium phosphate esters of the formula

Vanadyl pyrophosphate oxidation catalyst precursors

An improved process for calcination and activation of a catalyst containing mixed oxides of vanadium and phosphorus (V/P/O) involving the addition of spray dried catalyst precursor to a fluidizing oxygen containing gas at a controlled rate such that the temperature is maintained at a range of 370 to 410.degree. C. (preferably 390.+-.5.degree. C.). The catalyst precursor experiences, in addition to rapid temperature rise, dehydration/calcination at this elevated temperature in the fluidized state for an average range of residence time of less than about 4 hours at 3.5 atm of air or above, and up to 20 hours at 1 atm of air while simultaneously and continuously maintaining an average V.sub.ox of 4.55 or less. Such a process is useful in preparing a V/P/O catalyst that exhibits enhanced activity for the oxidation of n-butane to maleic anhydride. The novel process also provides an improved method for start-up of a commercial scale recirculating solids reactor.

Process for the calcination/activation of V/P/O catalyst

An improved process for calcination and activation of a catalyst containing mixed oxides of vanadium and phosphorus (V/P/O) comprising the steps of calcining a hydrated V/P/O or V/P/O- SiO.sub.2 catalyst precursor at a temperature range of 375.degree. to 400.degree. C. for sufficient time to dehydrate said catalyst precursor while simultaneously and continuously controlling the oxygen level such as to maintain the Vox in the range of 3.825 to 4.175; and then activating the dehydrated catalyst precursor by further heating at a range of 340.degree. to 500.degree. C. in the presence of a gaseous atmosphere containing n-butane at a partial pressure not exceeding 0.20 atm while simultaneously and continuously controlling the oxygen level such as to maintain the Vox in the range of 3.95 to 4.15. Such a V/P/O catalyst is useful in the preparation of maleic anhydride from n-butane.

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.

Vapor phase catalytic oxidation of N-butane to maleic anhydride

An improved process for preparing a superconducting composition having the formula M.sub.W A.sub.E Cu.sub.V O.sub.K wherein M is selected from the group consisting of Bi, Tl, Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm Yb and Lu; A is at least one alkaline earth metal selected from the group consisting of Ba, Ca and Sr; x is at least 6; w is at least 1; z is at least 2 and v is at least 1; said composition having a superconducting transition temperature of above 77K, preferably above about 90 K; said process consisting essentially of (a) forming a suspension having an M:A:Cu atomic ratio of w:z:v by mixing A(OH).sub.2, AO or AO.sub.2 and M.sub.2 O.sub.3 with an aqueous solution of cupric carboxylate or cupric nitrate at a temperature from about 50.degree. C. to about 100.degree. C., or mixing A(OH).sub.2 with an aqueous solution of Cu carboxylate, nitrate or a mixture thereof and M carboxylate, nitrate or a mixture thereof at a temperature from about 50.degree. C. to about 100.degree. C.; (b) drying the suspension formed in step (a) to obtain a precursor powder; and (c) heating and cooling the powder under specified conditions to form the desired superconducting composition which can be formed into shaped articles.

Process for making superconductor powder

There is disclosed an improved process for preparing a superconducting composition having the formula M.sub.w A.sub.z Cu.sub.v O.sub.x wherein M is selected from the group consisting if Bi, Tl, Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm Yb and Lu; A is at least one alkaline earth metal selected from the group consisting of Ba, Ca and Sr; x is at least 6; w is at least 1; z is at least 2 and v is at least 1; said composition having a superconducting transition temperature of above 77 K, preferably above about 90 K; said process consisting essentially of (a) forming a suspension having an M:A:Cu atomic ratio of w:z:v by mixing A(OH).sub.2, AO or AO.sub.2 and M.sub.2 O.sub.3 with an aqueous solution of cupric carboxylate or cupric nitrate at a temperature from about 50.degree. C. to about 100.degree. C., or mixing A(OH).sub.2 with an aqueous solution of Cu carboxylate, nitrate or a mixture thereof and M carboxylate, nitrate or a mixture thereof at a temperature from about 50.degree. C. to about 100.degree. C.; (b) drying the suspension formed in step (a) to obtain a precursor powder; and (c) heating and cooling the powder under specified conditions to form the desired superconducting composition. Shaped articles thereof are also disclosed.

Process for making superconductors using barium hydroxide

A process for preparing the superconductive material MBa.sub.2 Cu.sub.3 O.sub.x, M being, inter alia, yttrium and x being from about 6.5-7 and a precursor material MBa.sub.2 Cu.sub.3 O.sub.y, y being from about 6-6.5, by controlled heating and cooling in a controlled atmosphere.

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Wilmington, DE, United States of America

Harold S Horowitz