It is an object of the present invention to provide a composite oxide catalyst which can suppress the generation of CO.sub.2 and CO and improve the yield of an unsaturated nitrile in a method for subjecting propane or isobutane to a vapor-phase catalytic ammoxidation reaction to produce a corresponding unsaturated nitrile, and a method for producing the composite oxide catalyst, and a method for producing an unsaturated nitrile using the composite oxide catalyst. A composite oxide catalyst used for a vapor-phase catalytic oxidation reaction or vapor-phase catalytic ammoxidation reaction of propane or isobutane, the composite oxide catalyst comprising a composite oxide represented by the following composition formula (1):
Mo.sub.1V.sub.aSb.sub.bNb.sub.cW.sub.dZ.sub.eO.sub.n(1),
wherein the component Z is one or more element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba; a, b, c, d, e, and n represent atomic ratios of the elements; and 0.1a<0.2, 0.15b0.5, 0.01c 0.5, 0d0.4, 0e0.2, and 0.60<a/b<1.00.

It is an object of the present invention to provide a composite oxide catalyst which can suppress the generation of CO.sub.2 and CO and improve the yield of an unsaturated nitrile in a method for subjecting propane or isobutane to a vapor-phase catalytic ammoxidation reaction to produce a corresponding unsaturated nitrile, and a method for producing the composite oxide catalyst, and a method for producing an unsaturated nitrile using the composite oxide catalyst. A composite oxide catalyst used for a vapor-phase catalytic oxidation reaction or vapor-phase catalytic ammoxidation reaction of propane or isobutane, the composite oxide catalyst comprising a composite oxide represented by the following composition formula (1):
Mo.sub.1V.sub.aSb.sub.bNb.sub.cW.sub.dZ.sub.eO.sub.n(1),
wherein the component Z is one or more element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba; a, b, c, d, e, and n represent atomic ratios of the elements; and 0.1a<0.2, 0.15b0.5, 0.01c 0.5, 0d0.4, 0e0.2, and 0.60<a/b<1.00.

A process is provided for control of an ammoxidation reactor. More specifically, the process includes controlling an amount of oxygen added to the reactor, steam temperature and linear velocity to minimize reactor temperature deviations.

A process is provided for control of an ammoxidation reactor. More specifically, the process includes controlling an amount of oxygen added to the reactor, steam temperature and linear velocity to minimize reactor temperature deviations.

A method for producing an oxide catalyst containing Mo, V, Sb, and Nb, the method including: a raw material preparation step including sub-step (I) of preparing an aqueous mixed liquid (A) containing Mo, V, and Sb, sub-step (II) of adding hydrogen peroxide to the aqueous mixed liquid (A), thereby facilitating oxidation of the aqueous mixed liquid (A) and obtaining an aqueous mixed liquid (A), and sub-step (III) of mixing the aqueous mixed liquid (A) and a Nb raw material liquid (B), thereby obtaining an aqueous mixed liquid (C); a drying step of drying the aqueous mixed liquid (C), thereby obtaining a dried powder; and a calcination step of calcining the dried powder under an inert gas atmosphere, wherein a time elapsed from addition of the hydrogen peroxide to the aqueous mixed liquid (A) to mixing the Nb raw material liquid (B) therewith is less than 5 minutes and the aqueous mixed liquid (A) before being subjected to the sub-step (III) has an oxidation-reduction potential of 150 to 350 mV.

A method for producing an oxide catalyst containing Mo, V, Sb, and Nb, the method including: a raw material preparation step including sub-step (I) of preparing an aqueous mixed liquid (A) containing Mo, V, and Sb, sub-step (II) of adding hydrogen peroxide to the aqueous mixed liquid (A), thereby facilitating oxidation of the aqueous mixed liquid (A) and obtaining an aqueous mixed liquid (A), and sub-step (III) of mixing the aqueous mixed liquid (A) and a Nb raw material liquid (B), thereby obtaining an aqueous mixed liquid (C); a drying step of drying the aqueous mixed liquid (C), thereby obtaining a dried powder; and a calcination step of calcining the dried powder under an inert gas atmosphere, wherein a time elapsed from addition of the hydrogen peroxide to the aqueous mixed liquid (A) to mixing the Nb raw material liquid (B) therewith is less than 5 minutes and the aqueous mixed liquid (A) before being subjected to the sub-step (III) has an oxidation-reduction potential of 150 to 350 mV.

The present invention relates to catalyst compositions containing a mixed oxide catalyst of formula (I) or formula (II) as described herein, their preparation, and their use in a process for ammoxidation of various organic compounds to their corresponding nitriles and to the selective catalytic oxidation of excess NH.sub.3 present in effluent gas streams to N.sub.2 and/or NO.sub.x.

The present invention relates to catalyst compositions containing a mixed oxide catalyst of formula (I) or formula (II) as described herein, their preparation, and their use in a process for ammoxidation of various organic compounds to their corresponding nitriles and to the selective catalytic oxidation of excess NH.sub.3 present in effluent gas streams to N.sub.2 and/or NO.sub.x.

An apparatus for efficiently removing the exuded substance and/or the attached substance on the surface of a catalyst (catalyst surface substance) from the catalyst is provided. The apparatus comprising a main body, the apparatus for removing a catalyst surface substance present on a surface of a catalyst from the catalyst by bringing a gas flow into contact with the catalyst housed in the main body, wherein a gas flow length in a flow direction of the gas flow is 55 mm or more, and an average flow velocity of the gas flow is 80 m/s or more and 500 m/s or less in terms of a linear velocity at 15 C. and 1 atm.

An apparatus for efficiently removing the exuded substance and/or the attached substance on the surface of a catalyst (catalyst surface substance) from the catalyst is provided. The apparatus comprising a main body, the apparatus for removing a catalyst surface substance present on a surface of a catalyst from the catalyst by bringing a gas flow into contact with the catalyst housed in the main body, wherein a gas flow length in a flow direction of the gas flow is 55 mm or more, and an average flow velocity of the gas flow is 80 m/s or more and 500 m/s or less in terms of a linear velocity at 15 C. and 1 atm.