JP3966573B2 - Catalyst for nitrile compound production - Google Patents

Description

【００２４】
【発明の効果】
本発明によればモリブデン、アンチモン、クロムを必須とした触媒を用いる事により、反応系にハロゲン化物等のプロモーターを必要とする事なしに、又アルカン分圧を高める事なしに高い収率でニトリル類を製造する事ができるアンモ酸化用触媒を提供することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst for ammoxidation used for producing nitriles using alkanes such as propane and isobutane as raw materials, and a method for producing nitriles using the same. Nitriles such as acrylonitrile and methacrylonitrile are industrially produced as important intermediates such as fibers, synthetic resins, and synthetic rubbers. In addition, nitrile components such as by-product cyanic acid and acetonitrile are also used as industrial raw materials and solvents.
[0002]
[Prior art]
Unsaturated nitriles such as acrylonitrile and methacrylonitrile are produced in large quantities as important intermediates for various industrial products. Conventionally, the production method is generally a method in which molecular oxygen and ammonia are subjected to gas phase catalytic ammoxidation using alkenes, that is, propylene, isobutene and the like as raw materials in the presence of a catalyst. On the other hand, in recent years, due to the price difference between alkenes and alkanes, efforts have been focused on the development of methods using many alkanes as raw materials from more expensive alkanes as raw materials. For example, among catalyst systems used to produce acrylonitrile and methacrylonitrile by ammoxidation using propane or isobutane as a starting material, a catalyst such as a halide is used as a Mo-Ce oxide catalyst (US Patent No. 3,746,737), Mo—Ce—Te-based oxide catalyst (US Pat. No. 3,833,638), Mo—Ce—Bi based, Mo—Ce—Te based oxide catalyst ( Japanese Laid-Open Patent Publication No. 47-13313), Sb-U oxide catalysts (Japanese Patent Publication No. 50-17046), and the like have been proposed.
[0003]
Sb-Sn-based, As-Sn-based, Mo-Sn-based, V-Cr-based oxide catalysts (above Japanese Patent Publication No. 50-28940), V-Sb-based oxidation are those in which the partial pressure of propane or the like is increased. Product catalyst (Japanese Patent Laid-Open No. 47-33783, Japanese Patent Publication No. 50-23016), V-Sb-W-based oxide catalyst (Japanese Patent Laid-Open No. 2-261544), V-Sn-Sb-Cu-Bi-based V-Sn-Sb-Cu-Te-based oxide catalyst (JP-A-4-275266), Mo-Bi-Fe-Al-based oxide catalyst (JP-A-3-157356), Mo-Cr- Te-based oxide catalysts (US Pat. No. 5,171,876), Mo—V—Te—Nb-based oxide catalysts (Japanese Patent Laid-Open No. 4-235153), and the like have been proposed.
[0004]
Others include a Mo—Bi—Cr-based oxide catalyst (JP-A-7-215925), a Cr—Sb—W-based oxide catalyst (JP-A-7-157461), and a Mo—Sb—W-based oxidation. A product catalyst (Japanese Patent Laid-Open No. 7-157462), a Mo—Bi—Cr—Nb-based oxide catalyst (Japanese Patent Laid-Open No. 6-116225), and the like have been proposed.
[0005]
[Problems to be solved by the invention]
However, among these catalyst systems, a system in which a small amount of halide or the like is added as a promoter to the reaction system is not preferable because of problems such as corrosion of the reactor. Further, in a system in which the partial pressure of propane is increased, it is necessary to recycle unreacted propane, which makes it an energy consuming process and is not a preferable method. Further, a system mainly composed of an element that is highly volatile and toxic and has high toxicity such as Te is not preferable because of problems in process operability and safety during inspection and repair.
[0006]
The present invention has been made to solve such drawbacks, and provides a catalyst having molybdenum, antimony and chromium as essential components as a catalyst for ammoxidation of alkanes to produce nitriles. It is. Further, the present invention provides a method for producing a nitrile compound such as acrylonitrile, methacrylonitrile, hydrocyanic acid, acetonitrile, etc. at a high yield using this catalyst.
[0007]
[Means for Solving the Problems]
As a result of various investigations on the production method of nitriles using alkanes as a raw material, the present inventor has found so far without using a promoter such as a halide or without increasing the partial pressure of alkane. The present invention has been accomplished by finding a method capable of producing nitriles and other effective nitrile components with a new composition that has not been obtained.
[0008]
That is, the gist of the present invention is characterized in that, in the method for producing nitriles by ammoxidation of alkanes in the presence of a catalyst, a composite oxide containing three elements of molybdenum, antimony and chromium as essential components is used as the catalyst. This is a method for producing a nitrile compound.
The present invention is described in detail below.
The gist of the present invention is to use a composite oxide solid catalyst containing molybdenum, antimony and chromium as essential components. This catalyst system is represented by the following formula (1).
[0009]
_{Mo 1 Sb a Cr b X c} O n (1)
(Time wherein, X represents at least one element selected from the group consisting of alkali metals or al, a, b, c are each represents Sb, Cr, the number of atoms of X, was 1 the number of atoms of Mo,
0.01 ≦ a ≦ 50
0.67 ≦ b ≦ 50
0 ≦ c ≦ 50
And n is a value determined by the valence of the existing element. )
[0010]
About the coefficient of the said Formula (1), Preferably they are a = 0.01-25 and b = 0.67-7 .
Further, the catalyst used in the present invention is further supported on the composite oxide represented by the above formula (1) on silica, alumina, silica alumina, magnesia, titanium oxide, niobium oxide, or a mixture thereof, thereby reducing the ratio of the catalyst. It is also possible to increase the surface area and physical strength.
The method for preparing the composite oxide catalyst is, for example, as follows.
[0011]
If the active ingredient is _{Mo 1 Sb a Cr b X c} O n, a chromium nitrate aqueous solution was added to a predetermined amount of ammonium heptamolybdate solution, further adding a slurry suspension of antimony trioxide. After sufficiently stirring and mixing, the mixture is dried by a method such as spray drying, evaporation to dryness, or vacuum drying to obtain a solid product. This is fired at 400 to 1000 ° C. to obtain the target product.
Firing is generally performed in the air, but can be performed under high oxygen concentration or low oxygen concentration, or in an inert gas such as nitrogen or helium or in vacuum. The firing method can also be carried out in a fixed firing furnace, a fluid firing furnace, a rotary firing furnace, a band firing furnace or the like.
[0012]
There is no particular limitation on the catalyst raw material used in the present invention. In addition to ammonium heptamolybdate, molybdenum trioxide, molybdenum trichloride, phosphomolybdic acid, or the like can be used as molybdenum. As antimony, antimony trioxide, antimony tetraoxide, antimony pentoxide, antimonic acid, antimony trichloride, antimony pentachloride, and the like can be used. As chromium, nitrate, chromic chloride, chromium acetate and the like can be used. For other substances, nitrates, oxides, chlorides, organic acid salts and the like can be used. In addition, there are no restrictions on the raw materials when silica, alumina, silica alumina, magnesia, titanium oxide, niobium oxide, etc. are used, and it is possible to selectively use compacts, oxides, hydroxide powders, sols, gels, etc. .
[0013]
The shape of these catalysts is not particularly limited. It can be molded and used with a tableting machine, an extrusion molding machine, a granulating machine or the like after drying or baking. When prepared by the spray drying method, it can be used as it is without being molded.
As the source gas for ammoxidation in the present invention, alkane, ammonia, oxygen and inert gas are usually used. The alkane used is not particularly limited, but propane, n-butane, and isobutane are preferably used in view of the usefulness of the resulting nitrile. There is no problem even if a small amount of alkene is contained in the alkane. Oxygen is not particularly required to have high purity, and oxygen in the air can be used, which is more economical. The alkane used may be supplied in a mixture with ammonia and an oxygen-containing gas, or may be supplied separately.
[0014]
The molar ratio of molecular oxygen supplied to the reaction is preferably about 0.2 to 5 times the amount of alkane, and the ammonia molar ratio is preferably about 0.2 to 3 times. As the inert gas, an inert gas such as helium or nitrogen or water vapor can be used.
In the present invention, the ammoxidation reaction is preferably performed in the presence of the above catalyst, the reaction temperature is 300 to 600 ° C., and the contact time between the raw material gas and the catalyst is 0.1 to 30 seconds. The reaction pressure can be carried out under normal pressure as well as under reduced pressure. As the reaction method, a fixed bed type, a fluidized bed type, a moving bed type, and the like are possible.
[0015]
【Example】
Hereinafter, the present invention will be described in more detail using examples in which propane is used as the alkane, but the present invention is not limited to these examples as long as it does not exceed the gist thereof.
In the following examples, alkane conversion (%), product compound selectivity (%), and single stream yield (%) are calculated by the following equations.
Alkane conversion rate (%) = [(number of moles of reacted alkane) / (number of moles of supplied alkane)] × 100
Selectivity of product compound (%) = [(mole number of product compound) / (mole number of reacted alkane)] × [(carbon number of product compound) / (carbon number of raw material alkane)] × 100
Single stream yield (%) = [(moles of product compound) / (moles of supplied alkane)] × [(carbon number of product compound) / (carbon number of raw material alkane)] × 100
[0016]
Example 1
Dissolve 73.1 g of ammonium heptamolybdate in 150 ml of warm water. To this was added 115.4 g of chromium nitrate dissolved in 120 ml of warm water. Subsequently, 20.2 g of antimony trioxide dispersed in 200 ml of warm water was added, the liquid temperature was set to about 80 ° C., and the liquid volume was kept constant and stirred for 4 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 150 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, baking was performed at 300 ° C. for 2 hours and further at 600 ° C. for 2 hours. The composition of the resulting catalyst was _{Mo 1 Sb 0.33 Cr 0.67 O n} .
1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS (stainless steel) and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/3/2/8/1 (molar ratio), the contact time with the catalyst was 5 seconds, and the reaction temperature was 520 ° C. The results are shown in Table 1.
[0017]
(Example 2)
Dissolve 72.2 g of ammonium heptamolybdate in 150 ml of warm water. To this was added 114.0 g of chromium nitrate and 2.75 g of potassium nitrate dissolved in 120 ml of warm water. Subsequently, 19.9 g of antimony trioxide dispersed in 200 ml of warm water was added, the liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 4 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 150 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, baking was performed at 300 ° C. for 2 hours and further at 600 ° C. for 2 hours. The composition of the resulting catalyst was _{Mo 1 Sb 0.33 Cr 0.67 K 0.067} O n.
1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/3/2/8/1 (molar ratio), the contact time with the catalyst was 5 seconds, and the reaction temperature was 520 ° C. The results are shown in Table 1.
[0018]
(Example 3)
To 16.4 g of silica sol having a silica content of 30% by weight, 2.42 g of ammonium heptamolybdate was dissolved in 5 ml of warm water and added. Next, 10.93 g of chromium nitrate dissolved in 23 ml of warm water and 5.97 g of antimony trioxide dispersed in 45 ml of warm water were added, and finally 48.5 g of alumina sol having an alumina content of 10% by weight was added. The liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 5 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 120 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, firing was performed in air at 450 ° C. for 3 hours and in an atmosphere of 10% oxygen concentration at 600 ° C. for 3 hours. The composition of the resulting catalyst was _{Mo 1 Sb 3.0 Cr 2.0 O n} / (25 wt% SiO ₂ +25 wt% Al ₂ O _3). 1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/2/4 / 7.5 / 1 (molar ratio), the contact time with the catalyst was 0.7 seconds, and the reaction temperature was 540 ° C. The results are shown in Table 1.
[0019]
Example 4
To 16.7 g of silica sol having a silica content of 30% by weight, 2.33 g of ammonium heptamolybdate was dissolved in 5 ml of warm water and added. Next, 12.59 g of chromium nitrate dissolved in 30 ml of warm water and 5.73 g of antimony trioxide dispersed in 45 ml of warm water were added, and finally 48.5 g of alumina sol having an alumina content of 10% by weight was added. The liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 5 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 120 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, firing was performed in air at 450 ° C. for 3 hours and in an atmosphere of 10% oxygen concentration at 600 ° C. for 3 hours. The composition of the resulting catalyst was _{Mo 1 Sb 3.0 Cr 2.4 O n} / (25 wt% SiO ₂ +25 wt% Al ₂ O _3). 1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/2/4 / 7.5 / 1 (molar ratio), the contact time with the catalyst was 0.8 seconds, and the reaction temperature was 520 ° C. The results are shown in Table 1.
[0020]
(Example 5)
To 16.7 g of silica sol having a silica content of 30% by weight, 2.53 g of ammonium heptamolybdate was dissolved in 5 ml of hot water and added. Next, 9.12 g of chromium nitrate dissolved in 20 ml of warm water, 6.23 g of antimony trioxide dispersed in 50 ml of warm water were added, and finally 48.5 g of alumina sol having an alumina content of 10% by weight was added. The liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 5 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 120 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, firing was performed in air at 450 ° C. for 3 hours and in an atmosphere of 10% oxygen concentration at 600 ° C. for 3 hours. The composition of the resulting catalyst was _{Mo 1 Sb 3.0 Cr 1.6 O n} / (25 wt% SiO ₂ +25 wt% Al ₂ O _3). 1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/2/4 / 7.5 / 1 (molar ratio), the contact time with the catalyst was 0.8 seconds, and the reaction temperature was 540 ° C. The results are shown in Table 1.
[0021]
(Example 6)
To 16.7 g of silica sol having a silica content of 30% by weight, 2.69 g of ammonium heptamolybdate was dissolved in 6 ml of warm water and added. Next, 12.14 g of chromium nitrate dissolved in 25 ml of warm water and 5.52 g of antimony trioxide dispersed in 45 ml of warm water were added, and finally 48.5 g of alumina sol having an alumina content of 10% by weight was added. The liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 5 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 120 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, firing was performed in air at 450 ° C. for 3 hours and in an atmosphere of 10% oxygen concentration at 600 ° C. for 3 hours. The composition of the resulting catalyst was _{Mo 1 Sb 2.5 Cr 2.0 O n} / (25 wt% SiO ₂ +25 wt% Al ₂ O _3). 1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/2/4 / 7.5 / 1 (molar ratio), the contact time with the catalyst was 0.7 seconds, and the reaction temperature was 540 ° C. The results are shown in Table 1.
[0022]
(Example 7)
To 16.7 g of silica sol having a silica content of 30% by weight, 1.35 g of ammonium heptamolybdate was dissolved in 3 ml of warm water and added. Next, 12.12 g of chromium nitrate dissolved in 25 ml of warm water and 6.62 g of antimony trioxide dispersed in 50 ml of warm water were added, and finally 48.5 g of alumina sol having an alumina content of 10% by weight was added. The liquid temperature was about 80 ° C., and the liquid volume was kept constant and stirred for 5 hours. Further, the liquid temperature was raised and stirring was continued while evaporating water. The obtained paste was dried at 120 ° C. for 15 hours and then granulated to 10 to 24 mesh. Thereafter, firing was performed in air at 450 ° C. for 3 hours and in an atmosphere of 10% oxygen concentration at 600 ° C. for 3 hours. The composition of the resulting catalyst was _{Mo 1 Sb 6.0 Cr 4.0 O n} / (25 wt% SiO ₂ +25 wt% Al ₂ O _3). 1 ml of this catalyst was filled in a flow reactor with an inner diameter of 10 mm made of SUS and reacted. The raw material gas composition was propane / ammonia / oxygen / helium / water = 1/2/4 / 7.5 / 1 (molar ratio), the contact time with the catalyst was 0.8 seconds, and the reaction temperature was 540 ° C. The results are shown in Table 1.
[0023]
[Table 1]

[0024]
【The invention's effect】
According to the present invention, by using a catalyst essentially composed of molybdenum, antimony and chromium, a nitrile can be obtained in a high yield without requiring a promoter such as a halide in the reaction system and without increasing the alkane partial pressure. It was possible to provide an ammoxidation catalyst capable of producing a catalyst.

Claims (3)

A catalyst for ammoxidation comprising a complex oxide represented by the following formula (1) and producing nitriles by reacting alkanes with molecular oxygen and ammonia.
_{Mo 1 Sb a Cr b X c} O n (1)
(Time wherein, X represents at least one element selected from the group consisting of alkali metals or al, a, b, c are each represents Sb, Cr, the number of atoms of X, was 1 the number of atoms of Mo,
0.01 ≦ a ≦ 50
0.67 ≦ b ≦ 50
0 ≦ c ≦ 50
And n is a value determined by the valence of the existing element. )   A catalyst for ammoxidation in which the composite oxide according to claim 1 is further supported on an oxide comprising silica, alumina, silica alumina, magnesia, titanium oxide, niobium oxide, or a mixture thereof.   A method for producing a nitrile characterized by using the catalyst for ammoxidation according to claim 1 or 2 when producing a nitrile from an alkane, molecular oxygen and ammonia.