Method for stabilizing a phosphorus-vanadium-oxygen complex catalyst

Claim 1

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of about 0.5 to 5, which comprises: (A) Contacting said catalyst at deactivation conditions including a temperature in the range of from about 350° to 600° C. with a gaseous mixture containing molecular oxygen for a period of greater than about 1 hour; (B) Contacting said catalyst with an effective amount of a material selected from the group consisting of: (1) Molecular chlorine or fluorine or mixtures thereof; (2) Halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the following formula: C(X).sub.n where each X is a selected halide and n is an integer from 1 to 4, any remaining radicals being hydrogen or mixtures thereof; (3) Organic halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the formula: R(X.sub.1).sub.m where R is alkane, alkene or alkyne of straight or branched structure having at least two carbon atoms and X 1 is independently a primary, secondary, or tertiary halide and m is an integer of from 1 to about 20 consistent with the number of carbon atoms of said structure or mixtures; (4) hydrogen halides; or mixtures thereof at reactivation conditions including a temperature in the range of from about 300° to about 500° C.; and (c) repeating the sequence of steps (A) and (B) at least once.

Claim 2

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of about 0.5 to 5, which comprises: (A) Contacting said catalyst at deactivation conditions including a temperature in the range of from about 350° to 600° C. with a gaseous mixture containing molecular oxygen for a period of greater than about 1 hour; (B) Contacting said catalyst with an effective amount of a material selected from the group consisting of: (1) Molecular chlorine or fluorine or mixtures thereof; (2) Halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the following formula: C(X).sub.n where each X is a selected halide and n is an integer from 1 to 4, any remaining radicals being hydrogen or mixtures thereof; (3) Organic halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the formula: R(X.sub.1).sub.m where R is alkane, alkene or alkyne of straight or branched structure having at least two carbon atoms and X 1 is independently a primary, secondary, or tertiary halide and m is an integer of from 1 to about 20 consistent with the number of carbon atoms of said structure or mixtures; (4) hydrogen halides; or mixtures thereof at reactivation conditions including a temperature in the range of from about 300° to about 500° C.; and (c) repeating the sequence of steps (A) and (B) at least once.

Claim 10

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of about 0.5 to 5, which comprises: (A) Contacting said catalyst at deactivating conditions including a temperature in the range of from about 350° to 600° C. with a gaseous mixture containing molecular oxygen and a hydrocarbon having less than about ten carbon atoms per molecule for a period of greater than about 1 hour. (B) Contacting said catalyst with an effective amount of a material selected from the group consisting of: (1) Molecular chlorine or fluorine or mixtures thereof; (2) Halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the following formula: C(X).sub.n where each X is a selected halide and n is an integer from 1 to 4, any remaining radicals being hydrogen or mixtures thereof; (3) Organic halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the formula: R(X.sub.1).sub.m where R is alkane, alkene or alkyne of straight or branched structure having at least two carbon atoms and X 1 is independently a primary, secondary, or tertiary halide and m is an integer of from 1 to about 20 consistent with the number of carbon atoms of said structure or mixtures; (4) Hydrochloric acid; or mixtures thereof at reactivation conditions including a temperature in the range of from about 300° to about 500° C.; and (c) repeating the sequence of steps (A) and (B) at least once.

Claim 11

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of about 0.5 to 5, which comprises: (A) Contacting said catalyst at deactivating conditions including a temperature in the range of from about 350° to 600° C. with a gaseous mixture containing molecular oxygen and a hydrocarbon having less than about ten carbon atoms per molecule for a period of greater than about 1 hour. (B) Contacting said catalyst with an effective amount of a material selected from the group consisting of: (1) Molecular chlorine or fluorine or mixtures thereof; (2) Halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the following formula: C(X).sub.n where each X is a selected halide and n is an integer from 1 to 4, any remaining radicals being hydrogen or mixtures thereof; (3) Organic halides of fluorine, chlorine, bromine or iodine being in the vapor state above about 250° C. at atmospheric pressure represented by the formula: R(X.sub.1).sub.m where R is alkane, alkene or alkyne of straight or branched structure having at least two carbon atoms and X 1 is independently a primary, secondary, or tertiary halide and m is an integer of from 1 to about 20 consistent with the number of carbon atoms of said structure or mixtures; (4) Hydrochloric acid; or mixtures thereof at reactivation conditions including a temperature in the range of from about 300° to about 500° C.; and (c) repeating the sequence of steps (A) and (B) at least once.

Claim 19

A method for stabilizing a phosphorus-vanadium-oxide catalyst having pentavalent phosphorus and vanadium with an average valence in the range of from about 3.9 to about 4.5, an atomic ratio in the range of from about 1 to 2, which comprises: (A) contacting said catalyst at deactivation conditions including a temperature in the range of about 350° to 540° C. with a gaseous mixture containing molecular oxygen and a hydrocarbon having less than about seven carbon atoms per molecule for a period of greater than about one hour; (B) contacting said catalyst with an effective amount of a material selected from the group consisting of methyl chloride, carbon dichloride, carbon trichloride, or carbon tetrachloride or mixtures thereof, at reactivation conditions including a temperature in the range of from about 300° to about 500° C; (c) contacting said catalyst with steam at a temperature in the range of from about 400° to 500° C; and (D) repeating the sequence of steps (A), (B) and (C) at least once.

Claim 20

A method for stabilizing a phosphorus-vanadium-oxide catalyst having pentavalent phosphorus and vanadium with an average valence in the range of from about 3.9 to about 4.5, an atomic ratio in the range of from about 1 to 2, which comprises: (A) contacting said catalyst at deactivation conditions including a temperature in the range of about 350° to 540° C. with a gaseous mixture containing molecular oxygen and a hydrocarbon having less than about seven carbon atoms per molecule for a period of greater than about one hour; (B) contacting said catalyst with an effective amount of a material selected from the group consisting of methyl chloride, carbon dichloride, carbon trichloride, or carbon tetrachloride or mixtures thereof, at reactivation conditions including a temperature in the range of from about 300° to about 500° C; (c) contacting said catalyst with steam at a temperature in the range of from about 400° to 500° C; and (D) repeating the sequence of steps (A), (B) and (C) at least once.

Claim 25

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of from about 0.5 to about 5 and containing an atomic ratio of zinc to vanadium of from about 0.01 to about 0.3 which method comprises: (A) contacting said catalyst at a temperature above about 370° C. with a gas containing molecular oxygen and a hydrocarbon selected from the group consisting of normal butane, normal butene-1, normal butene-2, butadiene, benzene or mixtures thereof for greater than about one hour; (B) contacting said catalyst with carbon tetrachloride at a temperature in the range of from about 300° to about 500° C; and (C) repeating the sequence of steps (A) and (B) at least once.

Claim 26

A method for stabilizing a phosphorus-vanadium-oxide catalyst having an atomic ratio of phosphorus to vanadium in the range of from about 0.5 to about 5 and containing an atomic ratio of zinc to vanadium of from about 0.01 to about 0.3 which method comprises: (A) contacting said catalyst at a temperature above about 370° C. with a gas containing molecular oxygen and a hydrocarbon selected from the group consisting of normal butane, normal butene-1, normal butene-2, butadiene, benzene or mixtures thereof for greater than about one hour; (B) contacting said catalyst with carbon tetrachloride at a temperature in the range of from about 300° to about 500° C; and (C) repeating the sequence of steps (A) and (B) at least once.