Zn and/or Ga promoted multi-metal oxide catalyst

#The present invention relates to an improved catalyst for the oxidation of alkanes or a mixture of alkanes and alkenes to their corresponding unsaturated carboxylic acids by vapor phase catalytic oxidation; to a method of making the catalyst; and to a process for the vapor phase catalytic oxidation of alkanes or a mixture of alkanes and alkenes to their corresponding unsaturated carboxylic acids.

#The present invention also relates to a method of producing unsaturated nitrites by subjecting alkanes or a mixture of alkanes and alkenes to vapor phase catalytic oxidation in the presence of ammonia.

#Nitriles, such as acrylonitrile and methacrylonitrile, have been industrially produced as important intermediates for the preparation of fibers, synthetic resins, synthetic rubbers, and the like. The most popular method for producing such nitrites is to subject an olefin such as propene or isobutene to a catalytic reaction with ammonia and oxygen in the presence of a catalyst in a gaseous phase at a high temperature. Known catalysts for conducting this reaction include a Mo—Bi—P—O catalyst, a V—Sb—O catalyst, an Sb—U—V—Ni—O catalyst, a Sb—Sn—O catalyst, a V—Sb—W—P—O catalyst and a catalyst obtained by mechanically mixing a V—Sb—W—O oxide and a Bi—Ce—Mo—W—O oxide. However, in view of the price difference between propane and propene or between isobutane and isobutene, attention has been drawn to the development of a method for producing acrylonitrile or methacrylonitrile by an ammoxidation reaction wherein a lower alkane, such as propane or isobutane, is used as a starting material, and it is catalytically reacted with ammonia and oxygen in a gaseous phase in the presence of a catalyst.

#A catalyst of nominal composition Mo1.0V0.3Te0.23Nb0.08Zn0.06Ox was prepared in the following manner: 13.06 g of ammonium heptamolybdate tetrahydrate (Aldrich Chemical Company), 2.60 g of ammonium metavanadate (Alfa-Aesar), 3.91 g of telluric acid (Aldrich Chemical Company) and 1.32 g of zinc nitrate hexahydrate (Aldrich Chemical Company) were dissolved in 100 g water upon heating to 80° C. After cooling to 20° C., 59.11 g of an aqueous solution of niobium oxalate (Reference Metals Company) containing 0.93% Nb was mixed therewith to obtain a solution. The water of this solution was removed via a rotary evaporator at a temperature of 50° C. and a pressure of 28 mmHg to obtain 21 g of a precursor solid. This catalyst precursor solid was calcined in a crucible in a box furnace. (The crucible was placed in the box furnace with a 10 scfh flow of argon over the crucible, the furnace was then heated to 200° C. at 2° C./min and held there for one hour; then using a 3 scfh flow of argon, the oven was heated to 600° C. at 2° C./min and held there for two hours.) The catalyst, thus obtained, was pressed in a mold and then broken and sieved to 10-20 mesh granules. 10 g of these granules were packed into a stainless steel U-tube reactor (inside diameter: 1.1 cm) for the gas phase oxidation of propane. The U-tube reactor was placed in a molten salt bath and fed with a mixture of propane, air and steam having a feed ratio of propane/air/steam of 1/15/14 and having a space velocity of 1200 hr−1. The effluent of the reactor was condensed to separate a liquid phase and a gas phase. The gas phase was analyzed by gas chromatography to determine the propane conversion. The liquid phase was also analyzed by gas chromatography for the yield of acrylic acid. The results (along with residence time and reactor temperature) are shown in Table 1.

#A catalyst of nominal composition Mo1.0V0.3Te0.23Nb0.08Zn0.04Ox was prepared in the following manner: 13.33 g of ammonium heptamolybdate tetrahydrate (Aldrich Chemical Company), 2.65 g of ammonium metavanadate (Alfa-Aesar), 3.99 g of telluric acid (Aldrich Chemical Company) and 0.90 g of zinc nitrate hexahydrate (Aldrich Chemical Company) were dissolved in 100 g of water upon heating to 80° C. After cooling to 20° C., 60.35 g of an aqueous solution of niobium oxalate (Reference Metals Company) containing 0.93% Nb was mixed therewith to obtain a solution. The water of this solution was removed via a rotary evaporator at a temperature of 50° C. and a pressure of 28 mmHg to obtain 21 g of a precursor solid. This catalyst precursor solid was calcined in a crucible in a box furnace. (The crucible was placed in the box furnace with a 10 scfh flow of argon over the crucible, the furnace was then heated to 200° C. at 2° C./min and held there for one hour; then using a 3 scfh flow of argon, the oven was heated to 600° C. at 2° C./min and held there for two hours.) The catalyst,thus obtained, was pressed in a mold and then broken and sieved to 10-20 mesh granules. 10 g of these granules were packed into a stainless steel U-tube reactor (inside diameter: 1.1 cm) for the gas phase oxidation of propane. The U-tube reactor was placed in a molten salt bath and fed with a mixture of propane, air and steam having a feed ratio of propane/air/steam of 1/15/14 and having a space velocity of 1200 hr−1. The effluent of the reactor was condensed to separate a liquid phase and a gas phase. The gas phase was analyzed by gas chromatography to determine the propane conversion. The liquid phase was also analyzed by gas chromatography for the yield of acrylic acid. The results (along with residence time and reactor temperature) are shown in Table 1.

#A catalyst of nominal composition Mo1.0V0.3Te0.23Nb0.08Zn0.02Ox was prepared in the following manner: 13.62 g of ammonium heptamolybdate tetrahydrate (Aldrich Chemical Company), 2.71 g of ammonium metavanadate (Alfa-Aesar), 4.07 g of telluric acid (Aldrich Chemical Company) and 0.46 g of zinc nitrate hexahydrate (Aldrich Chemical Company) were dissolved in 100 g of water upon heating to 80° C. After cooling to 20° C., 61.64 g of an aqueous solution of niobium oxalate (Reference Metals Company) containing 0.93% Nb was mixed therewith to obtain a solution. The water of this solution was removed via a rotary evaporator at a temperature of 50° C. and a pressure of 28 mmHg to obtain 21 g of a precursor solid. This catalyst precursor solid was calcined in a crucible in a box furnace. (The crucible was placed in the box furnace with a 10 scfh flow of argon over the crucible, the furnace was then heated to 200° C. at 2° C./min and held there for one hour; then using a 3 scfh flow of argon, the oven was heated to 600° C. at 2° C./min and held there for two hours.) The catalyst, thus obtained, was pressed in a mold and then broken and sieved to 10-20 mesh granules. 10 g of these granules were packed into a stainless steel U-tube reactor (inside diameter: 1.1 cm) for the gas phase oxidation of propane. The U-tube reactor was placed in a molten salt bath and fed with a mixture of propane, air and steam having a feed ratio of propane/air/steam of 1/15/14 and having a space velocity of 1200 hr−1. The effluent of the reactor was condensed to separate a liquid phase and a gas phase. The gas phase was analyzed by gas chromatography to determine the propane conversion. The liquid phase was also analyzed by, gas chromatography for the yield of acrylic acid. The results (along with residence time and reactor temperature) are shown in Table 1. 2 TABLE 4 Residence Temp- Propane Acrylic Acid Acrylic Acid Ex- Time erature Conversion Selectivity Yield ample (sec) (° C.) (%) (%) (%) C. Ex. 1 3 380 17 71 12 Ex. 1 3 380 16 63 10 Ex. 2 3 380 19 84 16 Ex. 3 3 380 13 77 10