Process for preparing phosphorus-vanadium mixed oxide oxidation catalysts

Claim 2

A process for the preparation of a phosphorus-vanadium mixed oxide oxidation catalyst for the production of maleic anhydride wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr based upon a performance test conducted at a concentration of 1.5 mole percent hydrocarbon-in-air, a space velocity of 1450 hr -1 under a pressure of 1.055×10 2 kPa-G, and a temperature sufficient to maintain the hydrocarbon conversion within the range of 70 mole percent to 90 mole percent, which process comprises: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of alcohol-modifying agent; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 3

The process of claim 1 wherein the alcohol medium is essentially anhydrous.

Claim 4

The process of claim 1 wherein the alcohol-modifying agent is selected from the group consisting of hydrogen iodide, sulfur dioxide, fuming sulfuric acid, and surfactants.

Claim 5

The process of claim 3 wherein the alcohol-modifying agent is sulfur dioxide.

Claim 6

The process of claim 1 wherein the alcohol modifying agent is employed in an amount sufficient to provide an alcohol-modifying agent/vanadium-containing comppound mole ratio of 1.0.

Claim 7

The process of claim 1 wherein the phosphorus-containing compound is added to the vanadium-containing mixture before effecting the reduction of the vanadium.

Claim 8

The process of claim 1 wherein the phosphorus-containing compound is added to the vanadium-containing mixture after effecting the reduction of the vanadium.

Claim 9

The process of claim 1 wherein reduction of the vanadium is effected by heating the vanadium-containing slurry under reflux conditions.

Claim 10

The process of claim 8 wherein the reflux conditions are maintained for a period ranging from about four hours to about 20 hours.

Claim 11

The process of claim 1 wherein the alcohol is isobutyl alcohol.

Claim 12

The process of claim 1 wherein the vanadium-containing compound is vanadium pentoxide.

Claim 13

The process of claim 1 wherein the phosphorus-containing compound is phosphoric acid.

Claim 14

The process of claim 12 wherein the concentration of the phosphoric acid is at least 100%.

Claim 15

The process of claim 1 wherein the catalyst precursor is recovered by filtration.

Claim 16

The process of claim 1 wherein the catalyst precursor is formed into structures.

Claim 17

The process of claim 1 wherein the catalyst precursor is calcined in an air calcination mode.

Claim 18

The process of claim 1 wherein the catalyst precursor is calcined in a nitrogen/steam calcination mode.

Claim 19

The process of claim 1 wherein the catalyst precursor calcination temperature is from about 275° C. to about 425° C.

Claim 20

The process of claim 1 wherein the catalyst has a phosphorus/vanadium atom ratio from about 0.5 to about 2.0.

Claim 21

The process of claim 19 wherein the catalyst has a phosphorus/vanadium atom ratio from about 0.95 to about 1.2.

Claim 22

The process of claim 1 wherein the catalyst has an average valence state of vanadium from about +3.9 to about +4.6.

Claim 23

The process of claim 1 wherein the catalyst has an intrinsic surface area of about 10 m 2 /g to about 40 m 2 /g.

Claim 24

An oxidation catalyst for the production of maleic anhydride by the partial oxidation of non-aromatic hydrocarbons comprising the mixed oxides of phosphorus and vanadium, wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr., which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 25

An oxidation catalyst for the production of maleic anhydride by the partial oxidation of non-aromatic hydrocarbons comprising the mixed oxides of phosphorus and vanadium, wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr., which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 26

The process of claim 23 wherein the alcohol medium is essentially anhydrous.

Claim 27

The process of claim 23 wherein the alcohol-modifying agent is selected from the group consisting of hydrogen iodide, sulfur dioxide, fuming sulfuric acid, and surfactants.

Claim 28

The process of claim 25 wherein the alcohol-modifying agent is sulfur dioxide.

Claim 29

The process of claim 23 wherein the alcohol-modifying agent is employed in an amount sufficient to provide an alcohol-modifying agent/vanadium-containing compound mole ratio of 1.0.

Claim 30

The process of claim 23 wherein the phosphorus-containing compound is added to the vanadium-containing mixture before effecting the reduction of the vanadium.

Claim 31

The process of claim 23 wherein the phosphorus-containing compound is added to the vanadium-containing mixture after effecting the reduction of the vanadium.

Claim 32

The process of claim 23 wherein reduction of the vanadium is affected by heating the vanadium-containing slurry under reflux conditions.

Claim 33

The process of claim 30 wherein the reflux conditions are maintained for a period ranging from about four hours to about 20 hours.

Claim 34

The process of claim 23 wherein the alcohol is isobutyl alcohol.

Claim 35

The mixture of claim 23 wherein the vanadium-containing compound is vanadium pentoxide.

Claim 36

The process of claim 23 wherein the phosphorus-containing compound is phosphoric acid.

Claim 37

The process of claim 34 wherein the concentration of the phosphoric acid is at least 100%.

Claim 38

The process of claim 23 wherein the catalyst precursor is recovered by filtration.

Claim 39

The process of claim 23 wherein the catalyst precursor is formed into structures.

Claim 40

The process of claim 23 wherein the catalyst precursor is calcined in an air calcination mode.

Claim 41

The process of claim 23 wherein the catalyst precursor is calcined in a nitrogen/steam calcination mode.

Claim 42

The process of claim 23 wherein the catalyst precursor calcination temperature is from about 275° C. to about 425° C.

Claim 43

The process of claim 23 wherein the catalyst has a phosphorus/vanadium atom ratio from about 0.5 to about 2.0.

Claim 44

The process of claim 41 wherein the catalyst has a phosphorus/vanadium atom ratio from about 0.95 to about 1.2.

Claim 45

The process of claim 23 wherein the catalyst has an average valence state of vanadium from about +3.9 to about +4.6.

Claim 46

The catalyst composition of claim 23 wherein the catalyst has an intrinsic surface area of about 10 m 2 /g to about 40 m 2 /g.

Claim 47

An oxidation catalyst comprising the mixed oxides of phosphorus and vanadium characterized by an average valence state of vanadium from about +3.9 to about +4.6, a phosphorus/vanadium atom ratio of about 0.5 to about 2.0, and a macrostructure predominantly comprising generally spheroidal particles consisting of radially oriented three-dimensional networks of randomly shaped open cells, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 48

An oxidation catalyst comprising the mixed oxides of phosphorus and vanadium characterized by an average valence state of vanadium from about +3.9 to about +4.6, a phosphorus/vanadium atom ratio of about 0.5 to about 2.0, and a macrostructure predominantly comprising generally spheroidal particles consisting of radially oriented three-dimensional networks of randomly shaped open cells, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 49

The process of claim 45 wherein the alcohol medium is essentially anhydrous.

Claim 50

The process of claim 45 wherein the alcohol-modifying agent is selected from the group consisting of hydrogen iodide, sulfur dioxide, fuming sulfuric acid, and surfactants.

Claim 51

The process of claim 47 wherein the alcohol-modifying agent is sulfur dioxide.

Claim 52

The process of claim 45 wherein the alcohol-modifying agent is employed in an amount sufficient to provide an alcohol-modifying agent/vanadium-containing compound mole ratio of 1.0.

Claim 53

The process of claim 45 wherein the phosphorus-containing compound is added to the vanadium-containing mixture before effecting the reduction of the vanadium.

Claim 54

The process of claim 45 wherein the phosphorus-containing compound is added to the vanadium-containing mixture after effecting the reduction of the vanadium.

Claim 55

The process of claim 45 wherein reduction of the vanadium is effected by heating the vanadium-containing slurry under reflux conditions.

Claim 56

The process of claim 52 wherein the reflux conditions are maintained for a period ranging from about four hours to about 20 hours.

Claim 57

The process of claim 45 wherein the alcohol is isobutyl alcohol.

Claim 58

The process of claim 45 wherein the vanadium-containing compound is vanadium pentoxide.

Claim 59

The process of claim 45 wherein the phosphorus-containing compound is phosphoric acid.

Claim 60

The process of claim 56 wherein the concentration of the phosphoric acid is at least 100%.

Claim 61

The process of claim 45 wherein the catalyst precursor is recovered by filtration.

Claim 62

The process of claim 45 wherein the catalyst precursor is formed into structures.

Claim 63

The process of claim 45 wherein the catalyst precursor is calcined in an air calcination mode.

Claim 64

The process of claim 45 wherein the catalyst precursor is calcined in a nitrogen/steam calcination mode.

Claim 65

The process of claim 45 wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr.

Claim 66

The process of claim 45 wherein the catalyst has an intrinsic surface area of about 10 m 2 /g to about 40 m 2 /g.

Claim 67

A process for the preparation of a phosphorus-vanadium mixed oxide oxidation catalyst for the production of maleic anhydride wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr based upon a performance test conducted at a concentration of 1.5 mole percent hydrocarbon-in-air, a space velocity of 1450 hr -1 under a pressure of 1.055×10 2 kPa-G, and a temperature sufficient to maintain the hydrocarbon conversion within the range of 70 mole percent to 90 mole percent, which process comprises: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 68

A process for the preparation of a phosphorus-vanadium mixed oxide oxidation catalyst for the production of maleic anhydride wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr based upon a performance test conducted at a concentration of 1.5 mole percent hydrocarbon-in-air, a space velocity of 1450 hr -1 under a pressure of 1.055×10 2 kPa-G, and a temperature sufficient to maintain the hydrocarbon conversion within the range of 70 mole percent to 90 mole percent, which process comprises: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 69

An oxidation catalyst for the production of maleic anhydride by the partial oxidation of nonaromatic hydrocarbons comprising the mixed oxides of phosphorus and vanadium, wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr based upon a performance test conducted at a concentration of 1.5 mole percent hydrocarbon-in-air, a space velocity of 1450 hr -1 under a pressure of 1.055×10 2 kPa-G, and a temperature sufficient to maintain the hydrocarbon conversion within the range of 70 mole percent to 90 mole percent, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 70

An oxidation catalyst for the production of maleic anhydride by the partial oxidation of nonaromatic hydrocarbons comprising the mixed oxides of phosphorus and vanadium, wherein the catalyst exhibits a weight/weight productivity to maleic anhydride of at least 70 g MAN/kg cat.-hr based upon a performance test conducted at a concentration of 1.5 mole percent hydrocarbon-in-air, a space velocity of 1450 hr -1 under a pressure of 1.055×10 2 kPa-G, and a temperature sufficient to maintain the hydrocarbon conversion within the range of 70 mole percent to 90 mole percent, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 71

An oxidation catalyst comprising the mixed oxides of phosphorus and vanadium characterized by an average valence state of vanadium from about +3.9 to about +4.6, a phosphorus/vanadium atom ratio of about 0.5 to about 2.0, and a macrostructure predominantly comprising generally spheroidal particles consisting of radially oriented three-dimensional networks of randomly shaped open cells, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.

Claim 72

An oxidation catalyst comprising the mixed oxides of phosphorus and vanadium characterized by an average valence state of vanadium from about +3.9 to about +4.6, a phosphorus/vanadium atom ratio of about 0.5 to about 2.0, and a macrostructure predominantly comprising generally spheroidal particles consisting of radially oriented three-dimensional networks of randomly shaped open cells, which catalyst is prepared by the steps comprising: (a) introducing a substantially pentavalent vanadium-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 to form a slurry; (b) contacting the slurry with an effective amount of an alcohol-modifying agent selected from the group consisting of anionic, nonionic, zwitterionic, ampholytic surfactants, and mixtures thereof; (c) effecting the reduction of at least a portion of the vanadium to a valence state of +4; (d) adding a pentavalent phosphorus-containing compound to the vanadium-containing mixture before or after effecting the reduction to form a phosphorus-vanadium mixed oxide catalyst precursor; (e) recovering the phosphorus-vanadium mixed oxide catalyst precursor; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor at a temperature from about 250° C. to about 600° C.