JP2007326036A - Oxide catalyst for oxidation or ammoxidation - Google Patents

Abstract

A catalyst having the requirements of a fluidized bed catalyst and good selectivity of unsaturated nitrile or unsaturated carboxylic acid.
A comprises a component composition represented by _{Mo 1 V a Sb b Nb c} O n, has a structure indicating the specific X-ray diffraction diagram, either a, b, c of (II) ~ (V) And an oxide catalyst supported on 30 to 55% by weight of silica. (II) 0.28 ≦ a ≦ 0.30 and 0.26 ≦ b ≦ 0.28 and 0.08 ≦ c ≦ 0.10, (III) 0.28 ≦ a ≦ 0.30 and 0 .29 ≦ b ≦ 0.32, and 0.11 ≦ c ≦ 0.15, a <b, (IV) 0.30 <a ≦ 0.33, and 0.27 ≦ b ≦ 0.31, and 0 0.08 ≦ c ≦ 0.17, (V) 0.33 <a ≦ 0.36, and 0.25 <b ≦ 0.32, and 0.08 ≦ c ≦ 0.20.
[Selection figure] None

Description

  The present invention relates to an oxide catalyst used for producing an unsaturated nitrile by a gas phase catalytic ammoxidation reaction of propane or isobutane, or for producing an unsaturated carboxylic acid by a gas phase catalytic oxidation reaction of propane or isobutane.

  Recently, instead of propylene or isobutylene, propane or isobutane is used as a raw material, and technology for producing unsaturated nitriles and unsaturated carboxylic acids by gas phase catalytic ammoxidation reaction or gas phase catalytic oxidation reaction has attracted attention. Has been proposed. Among them, a catalyst that has attracted particular attention is an oxide catalyst composed of Mo—V—Sb—Nb mainly composed of molybdenum. For example, since disclosed in Patent Document 1, many patent documents have been disclosed. Has been. Most of these documents relate to a process for producing a catalyst and a technique for adding a fifth component to the catalyst. Those relating to the composition of the catalyst are only disclosed in Patent Documents 2 and 3, which indicate the difficulty in developing the composition of the catalyst system.

  By the way, the gas phase catalytic ammoxidation reaction or gas phase catalytic oxidation reaction of propane or isobutane is an exothermic reaction. In industrial implementation of these reactions, it is necessary for production to keep the reaction temperature uniform by suppressing heat storage in the reaction system. Considering these points, a fluidized bed reaction having a high heat removal efficiency is advantageous as a reaction system. However, in the fluidized bed reaction, there is a problem that the catalyst wears due to the collision between the catalysts or the collision between the catalyst and the reactor wall as the catalyst flows, and as a result, the fluidity of the catalyst decreases. Accordingly, the fluidized bed reaction catalyst is required to have sufficient strength to withstand abrasion. Therefore, silica, alumina, titania, silica-alumina, zirconia, diatomaceous earth, or the like is used as a catalyst carrier in order to increase the catalyst strength.

  Patent Document 4 states that "generally mixing inert particles with catalyst components improves the mechanical strength as a catalyst, but on the other hand, a decrease in activity as a catalyst is inevitable." In addition, when a catalyst is supported on a carrier in order to impart catalyst strength necessary for a fluidized bed reaction, there has been a problem in that performance degradation cannot be avoided. The reason is not clear, but it is essentially responsible for the catalytic activity due to the influence of the decrease in the catalyst components involved in the reaction by the addition of the support and the formation of complex oxides between the catalyst and the constituent elements of silica. This may be caused by changes in the composition or structure of the phase.

  On the other hand, a supported catalyst that dislikes performance degradation and has a small amount of support is not suitable as a fluidized bed reaction catalyst because the fluidity of the catalyst is poor or the catalyst strength is not sufficient to withstand the fluidized bed reaction. There's a problem.

In addition, the catalyst having molybdenum as a main component has a phenomenon in which Mo is scattered by the generation of sublimable molybdate MoO ₂ (OH) ₂ by water generated by gas phase ammoxidation reaction or gas phase catalytic oxidation reaction. It is known (for example, refer nonpatent literature 1). Therefore, in Patent Document 3, although a catalyst having a lower molybdenum content is studied than Patent Documents 1 and 2, etc., the yield and selectivity of unsaturated nitrile and unsaturated carboxylic acid are still insufficient.

For these reasons, the catalyst costs are met by including a large amount of constituent elements with abundant resources, such as silica, with the requirements of a fluidized bed catalyst used for gas phase catalytic ammoxidation reaction or gas phase catalytic oxidation reaction of propane or isobutane. Is a low-cost catalyst and has a relatively low molybdenum content compared to conventional catalysts, but has good reaction results such as yield and selectivity of the target product, unsaturated nitriles and unsaturated carboxylic acids. Was anxious.
Japanese Patent Laid-Open No. 9-157241 JP 2002-239382 A JP 2005-211184 A JP-A-7-144132 Buten (J.Buiten), Oxidation of propyrene by means of SnO2-MoO3 catalysts, "Journal of catalysis" (Netherlands), Elsevier 88, 1999

  An object of the present invention is to provide a catalyst having the requirements of a fluidized bed catalyst for producing an unsaturated nitrile by a gas phase catalytic ammoxidation reaction of propane or isobutane or an unsaturated carboxylic acid by a gas phase catalytic oxidation reaction of propane or isobutane. In addition, it is to provide a catalyst having a good yield and selectivity of an unsaturated nitrile or an unsaturated carboxylic acid, although the molybdenum content is relatively small as compared with the prior art.

As a result of intensive studies to solve the above problems, the present inventors have unexpectedly found excellent reaction results in a silica-supported catalyst of high silica even if the reaction results are insufficient with no silica supported. A catalyst composed of a novel composition that has not been known so far, and a catalyst having the requirements of a fluidized bed catalyst, an unsaturated nitrile by a gas phase catalytic ammoxidation reaction of propane or isobutane, or a gas phase contact of propane or isobutane A catalyst for producing an unsaturated carboxylic acid with high selectivity by an oxidation reaction has been found, and the present invention has been made.
That is, the present invention
[1] A silica-supported oxide catalyst used for producing an unsaturated nitrile by a gas phase catalytic ammoxidation reaction of propane or isobutane, or for producing an unsaturated carboxylic acid by a gas phase catalytic oxidation reaction of propane or isobutane,
The oxide catalyst includes a component composition represented by the general formula (I),
_{Mo 1 V a Sb b Nb c} O n (I)
(Wherein a, b, c and n represent the atomic ratio per Mo atom, and n is an atomic ratio determined by the oxidation state of the constituent metals.)
In an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, diffraction angles (2θ) are 7.8 ± 0.3 °, 8.9 ± 0.3 °, 22.1 ± 0.3 °, 27. In oxide catalysts having diffraction peaks at positions of 1 ± 0.3 °, 35.2 ± 0.3 ° and 45.2 ± 0.3 °, a, b and c are represented by the formulas (II) to (V) Is the value indicated by
(II) 0.28 ≦ a ≦ 0.30 and 0.26 ≦ b ≦ 0.28 and 0.08 ≦ c ≦ 0.10;
(III) 0.28 ≦ a ≦ 0.30, 0.29 ≦ b ≦ 0.32, and 0.11 ≦ c ≦ 0.15, a <b;
(IV) 0.30 <a ≦ 0.33 and 0.27 ≦ b ≦ 0.31 and 0.08 ≦ c ≦ 0.17;
(V) 0.33 <a ≦ 0.36, 0.25 <b ≦ 0.32, and 0.08 ≦ c ≦ 0.20;
A silica-supported oxide catalyst, wherein the oxide catalyst is supported on 30 to 55% by weight of silica,
[2] The silica-supported oxide catalyst is produced by calcining a dry powder obtained from a catalyst raw material liquid having a component of a silica-supported oxide catalyst at 500 to 700 ° C. in a gas atmosphere substantially free of oxygen. The silica-supported oxide catalyst according to the above item [1], wherein
[3] A method for producing an unsaturated carboxylic acid or an unsaturated nitrile by gas phase catalytic oxidation reaction or gas phase catalytic ammoxidation reaction of alkane,
A process for producing an unsaturated carboxylic acid or an unsaturated nitrile, comprising the step of bringing the alkane into contact with the silica-supported oxide catalyst according to [1] or [2] above;
I will provide a.

  According to the present invention, in producing an unsaturated nitrile by a gas-phase catalytic ammoxidation reaction of propane or isobutane, or an unsaturated carboxylic acid by a gas-phase catalytic oxidation reaction of propane or isobutane, the requirements for a fluidized bed catalyst are provided. In addition, it is possible to provide a catalyst having a good yield and selectivity of unsaturated nitrile or unsaturated carboxylic acid, although the molybdenum content is relatively small as compared with the conventional one.

  The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.

The silica-supported oxide catalyst according to the present invention is an oxide used for producing an unsaturated nitrile by a gas-phase catalytic ammoxidation reaction of propane or isobutane, or an unsaturated carboxylic acid by a gas-phase catalytic oxidation reaction of propane or isobutane. A catalyst comprising a component composition represented by general formula (I):
_{Mo 1 V a Sb b Nb c} O n (I)
(Wherein a, b, c and n represent the atomic ratio per Mo atom, and n is an atomic ratio determined by the oxidation state of the constituent metals.)
In an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, diffraction angles (2θ) are 7.8 ± 0.3 °, 8.9 ± 0.3 °, 22.1 ± 0.3 °, 27. In oxide catalysts having diffraction peaks at positions of 1 ± 0.3 °, 35.2 ± 0.3 ° and 45.2 ± 0.3 °, a, b and c are represented by formulas (II) to (V The oxide catalyst is supported on 30 to 55% by weight of silica:
(II) 0.28 ≦ a ≦ 0.30 and 0.26 ≦ b ≦ 0.28 and 0.08 ≦ c ≦ 0.10;
(III) 0.28 ≦ a ≦ 0.30, 0.29 ≦ b ≦ 0.32, and 0.11 ≦ c ≦ 0.15, a <b;
(IV) 0.30 <a ≦ 0.33 and 0.27 ≦ b ≦ 0.31 and 0.08 ≦ c ≦ 0.17;
(V) 0.33 <a ≦ 0.36, 0.25 <b ≦ 0.32, and 0.08 ≦ c ≦ 0.20.

  The above (II) is preferably 0.285 ≦ a ≦ 0.295, 0.265 ≦ b ≦ 0.275, and 0.085 ≦ c ≦ 0.095. The above (III) is preferably 0.285 ≦ a ≦ 0.295, 0.30 ≦ b ≦ 0.31, 0.12 ≦ c ≦ 0.14, and a <b. Further, the above (IV) is preferably 0.305 <a ≦ 0.32, 0.27 ≦ b ≦ 0.31, 0.09 ≦ c ≦ 0.13. Furthermore, the above (V) is preferably 0.34 <a ≦ 0.355, 0.26 <b ≦ 0.31, and 0.12 ≦ c ≦ 0.18.

  The silica-supported oxide catalyst according to the present invention has a specific X-ray diffraction pattern and also has an excellent catalyst in a limited range of Mo, V, Sb, Nb, and silica supported amount. Neither of these catalysts is known.

In the silica-supported oxide catalyst according to the present invention, the amount of silica is preferably 35 to 55% by weight, more preferably 37 to 43% by weight. The weight percentage of silica is defined by the following formula, where the weight of the oxide of formula (I) is W1 and the weight of silica is W2. W1 is a weight calculated based on the charged composition and the oxidation number of the charged metal component. W2 is a weight calculated based on the charged composition.
Silica weight% = 100 × W2 / (W1 + W2)

  When the silica weight percentage is less than 30 weight%, the acrylonitrile selectivity or acrylic acid selectivity is low when the silica weight percentage is greater than 60 weight%.

X-ray diffraction of the silica-supported oxide catalyst according to the present invention is performed under the following conditions.
X-ray source: CuKα1 + CuKα2
Detector: Scintillation counter Spectroscopic crystal: Graphite Tube voltage: 40 kV
Tube current: 190 mA
Divergent slit: 1 °
Scattering slit: 1 °
Light receiving slit: 0.3 mm
Scanning speed: 1 ° / min Sampling width: 0.02 °
Scanning method: 2θ / θ method

  The diffraction angle (2θ) of the silica-supported oxide catalyst of the present invention is 7.8 ± 0.2 °, 8.9 ± 0.2 °, 22.1 ± 0.2 °, 27.1 ± 0.00. It is preferable to have diffraction peaks at positions of 2 °, 35.2 ± 0.2 °, and 45.2 ± 0.2 °, and 7.8 ± 0.1 °, 8.9 ± 0.1 °, 22 It is more preferable to have diffraction peaks at positions of ± 1 ± 0.1 °, 27.1 ± 0.1 °, 35.2 ± 0.1 °, and 45.2 ± 0.1 °. The diffraction angle (2θ) preferably has a diffraction peak at a position of 6.7 ± 0.3 °, and more preferably has a diffraction peak at a position of 6.7 ± 0.1 °. Further, oxidation having peaks at diffraction angles (2θ) at 22.1 ± 0.3 °, 28.1 ± 0.3 °, 36.1 ± 0.3 °, and 45.2 ± 0.3 °. Preferably present, more preferably peaks at 22.1 ± 0.1 °, 28.1 ± 0.1 °, 36.1 ± 0.1 ° and 45.2 ± 0.1 °. have. The silica-supported oxide catalyst according to the present invention may exhibit a strong peak other than the above in the X-ray diffraction diagram as long as the use as a catalyst is not hindered.

  In addition to the composition of the above formula (I) of the present invention, W, Cr, Ti, Al, Ta, Zr, Hf, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Ag, Zn, B, In, Ge, Sn, P, Pb, Bi, Y, Ga, at least one element selected from rare earth elements and alkaline earth metals may be included. Preferably, Z is at least one element selected from Al, Ge, Sn, Zr, W, Ti, Cr, Ti, Ta, Re, B, In, P, Bi, Y, and a rare earth element. The amount added is 0 ≦ d ≦ 1, preferably 0 ≦ d ≦ 0.5, particularly preferably 0 ≦ d ≦ 0.1 with respect to the Mo1 atom.

The following compounds can be used as raw materials for the component metals for producing the silica-supported oxide catalyst according to the present invention.
As the molybdenum raw material, ammonium heptamolybdate, molybdenum oxide, molybdic acid, molybdenum oxychloride, molybdenum chloride, molybdenum alkoxide, and the like can be used, and ammonium heptamolybdate is preferable.

  As the vanadium raw material, ammonium metavanadate, vanadium oxide (V), oxychloride of vanadium, alkoxide of vanadium, or the like can be used, and ammonium metavanadate and vanadium oxide (V) are preferable.

  Antimony raw materials include antimony oxide (III), antimony oxide (IV), antimony oxide (V), metaantimonic acid (III), antimonic acid (V), ammonium antimonate (V), antimony chloride (III), chloride Organic acid salts such as antimony (III) oxide, antimony (III) nitrate, alkoxide of antimony, antimony tartrate, metal antimony, and the like can be used, and antimony (III) oxide is preferable.

Examples of the niobium raw material include niobic acid, NbCl ₅ , NbCl ₃ , Nb (OC ₂ H ₅ ) ₅ , niobium dicarboxylic acid compound aqueous solution obtained by dissolving niobic acid in a dicarboxylic acid compound solution, and the like. An aqueous solution of niobium dicarboxylic acid compound obtained by dissolving niobic acid in an aqueous dicarboxylic acid compound solution is preferred. As the dicarboxylic acid compound, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and pimelic acid are preferable, and oxalic acid is more preferable. The niobium-oxalic acid aqueous solution is preferably used. It is particularly preferable to use a niobium-oxalic acid aqueous solution as a hydrogen peroxide aqueous solution obtained by adding a hydrogen peroxide solution to a niobium-oxalic acid aqueous solution. The molar ratio of oxalic acid / niobium is preferably 1-6, more preferably 2-4. The molar ratio of hydrogen peroxide / niobium is preferably from 0.5 to 10, particularly preferably from 1 to 6.

  As raw materials for optional components, oxalates, hydroxides, oxides, nitrates, acetates, ammonium salts, carbonates, alkoxides and the like can be used.

  Silica sol, powder silica, a silica molded body, silica gel, and the like can be used as a raw material for silica as a catalyst carrier. The raw material which produces | generates a support | carrier component after a catalyst preparation process can also be used. The silica raw material is preferably silica sol stabilized with ammonium ions or powdered silica. Silica sol and powdered silica may be used singly or as a mixture of silica sol and powdered silica, but it is preferable to mix silica sol and powdered silica.

The silica-supported oxide catalyst according to the present invention is preferably produced through the following three steps of raw material preparation, drying and firing.
<Raw material preparation process>
Ammonium heptamolybdate, ammonium metavanadate, and antimony (III) oxide are suspended in water, and preferably reacted at 70 to 100 ° C. with stirring for 1 to 5 hours. The obtained mixed liquid containing molybdenum, vanadium, and antimony is liquid-phase oxidized with air oxidation or hydrogen peroxide to obtain a mixed liquid (A). When hydrogen peroxide is used for liquid phase oxidation, the molar ratio of hydrogen peroxide / Sb is preferably 0.5-2. It is preferable to oxidize until it becomes orange-brown visually. On the other hand, niobic acid is dissolved in an oxalic acid aqueous solution to prepare a niobium raw material liquid (B). It is preferable to add hydrogen peroxide to the niobium raw material liquid. The niobium raw material liquid (B) is added to the mixed liquid (A).
Silica can be obtained by adding silica sol in any step of the above preparation sequence to obtain a catalyst raw material liquid, but it is preferably added to the mixed liquid (A). In addition to the silica sol, it is preferable to further add fine particle powder silica such as Aerosil.
W, Cr, Ti, Al, Ta, Zr, Hf, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Ag, Zn, B, In, Ge, Sn, P, Pb, In the case of producing a catalyst containing Bi, Y, Ga, rare earth elements and alkaline earth metal, a catalyst raw material liquid can be obtained by adding raw materials containing these in any step of the above-mentioned preparation sequence.

<Drying process>
The oxide raw material liquid obtained in the raw material preparation step can be dried by spray drying or evaporation to dryness to obtain a dry powder. The atomization in the spray drying method can employ a centrifugal method, a two-fluid nozzle method, or a high-pressure nozzle method. As the drying heat source, air heated by steam, an electric heater or the like can be used. At this time, the dryer inlet temperature of hot air is preferably 150 to 300 ° C. Spray drying can also be performed simply by spraying the oxide raw material liquid onto an iron plate heated to 100 ° C to 300 ° C.

<Baking process>
An oxide can be obtained by firing the dry powder obtained in the drying step. Firing is carried out using a rotary furnace, tunnel furnace, tubular furnace, fluidized firing furnace or the like, and in an inert gas atmosphere such as nitrogen substantially free of oxygen, preferably with an inert gas flowing, preferably 500 to 900 ° C., preferably Is 590-650 ° C, more preferably 610-640 ° C. The firing time is 0.5 to 5 hours. Preferably it is 1-3 hours. The oxygen concentration in the inert gas is 1000 ppm or less, preferably 100 ppm or less as measured by gas chromatography or a trace oxygen analyzer. This firing can be repeated. Prior to this firing, pre-baking can be carried out at 200 ° C. to 420 ° C., preferably 250 ° C. to 350 ° C. for 10 minutes to 5 hours in an air atmosphere or under air circulation. Further, after firing, post-baking can be performed in an air atmosphere at 200 ° C. to 400 ° C. for 5 minutes to 5 hours.
The silica-supported oxide catalyst thus produced can be used as a catalyst for producing an unsaturated nitrile by subjecting propane or isobutane to gas phase catalytic ammoxidation. It can also be used as a catalyst for producing unsaturated carboxylic acids by gas phase catalytic oxidation of propane or isobutane. Preferably it is used as a catalyst for the production of unsaturated nitriles.

  The feedstock of propane or isobutane and ammonia used for the production of unsaturated nitriles does not necessarily have to be high purity, and industrial grade gases can be used. As the oxygen source supplied to the reaction system, air, air enriched with oxygen, or pure oxygen can be used. Further, water vapor, helium, argon, carbon dioxide gas, nitrogen, or the like may be supplied.

  In the case of gas phase catalytic ammoxidation, the molar ratio of ammonia supplied to the reaction system to propane or isobutane is 0.1 to 1.5, preferably 0.7 to 1.2, more preferably 0.9. -1.1. The molar ratio of molecular oxygen supplied to the reaction system to propane or isobutane is 0.2 to 6, preferably 2.0 to 3.0, more preferably 2.5 to 2.9.

  In the case of gas phase catalytic oxidation, the molar ratio of molecular oxygen supplied to the reaction system to propane or isobutane is 0.1 to 10, preferably 0.7 to 3. Although addition of water vapor to the reaction system is preferred, the molar ratio of water vapor supplied to the reaction system to propane or isobutane is 0.1 to 70, preferably 0.5 to 40.

The reaction pressure is 0.01 to 1 MPa in absolute pressure, preferably 0.02 to 0.3 MPa. The reaction temperature is 300 to 600 ° C, preferably 350 to 470 ° C. The contact time is 0.1 to 30 (g · s / ml), preferably 0.5 to 10 (g · s / ml). The contact time is defined by the following formula.
Contact time (g · sec / ml) = W / F × 60 × 273 / (273 + T) × ((P + 0.101) /0.101)
[W is the weight of the oxide catalyst (g), F is the flow rate of the raw material mixed gas (ml / min), T is the reaction temperature (° C.), and P is the reaction pressure (gauge pressure) (MPa). ]

  For the reaction, a conventional system such as a fixed bed, a fluidized bed, or a moving bed can be adopted, but a fluidized bed is preferable because of easy reaction control. The reaction may be a single flow method or a recycle method.

  The silica-supported oxide catalyst according to the present invention exhibits a high selectivity despite a high conversion rate. Conventionally, when the selectivity is high, the conversion rate is kept low, and a high conversion rate can be obtained at a high conversion rate. This means that the process load due to recycling is greatly reduced, so that energy consumption is suppressed and the process is reduced. The miniaturization and simplification. Even in the recycling method, the conversion rate in the reactor is preferably 60% or more.

  The present invention will be described in more detail with reference to the following examples and comparative examples of the present invention, but these are illustrative, and the present invention is not limited to the following examples. Those skilled in the art can implement the present invention by making various modifications to the embodiments shown below, and such modifications are included in the scope of the claims of the present application.

Propane conversion, acrylonitrile selectivity and acrylic acid selectivity;
In the examples and comparative examples, the propane conversion and the acrylonitrile selectivity follow the following definitions, respectively.
Propane conversion (%) = (moles of propane reacted) / (moles of propane fed) × 100
Acrylonitrile selectivity (%) = (number of moles of acrylonitrile produced) / (number of moles of reacted propane) × 100

<XRD measurement method>
The XRD of the obtained silica-supported oxide catalyst or oxide catalyst was measured using MXP-18 type manufactured by Mac Science.
About 0.5 g of the silica-supported oxide catalyst or oxide catalyst was placed in an agate mortar and manually pulverized for 2 minutes using an agate pestle, followed by classification to obtain an oxide powder having a particle size of 53 μm or less. The obtained oxide powder is placed in a depression (rectangular shape with a length of 20 mm, a width of 16 mm, and a depth of 0.2 mm) on the surface of a sample stage for XRD measurement, and pressed using a flat stainless steel spatula. The sample was prepared with a flat surface. X-ray diffraction was measured under the following conditions.
X-ray source: CuKα1 + CuKα2
Detector: Scintillation counter Spectroscopic crystal: Graphite Tube voltage: 40 kV
Tube current: 190 mA
Divergent slit: 1 °
Scattering slit: 1 °
Light receiving slit: 0.3 mm
Scanning speed: 1 ° / min Sampling width: 0.02 °
Scanning method: 2θ / θ method

[Example 1]
<Preparation of Nb raw material liquid (B)>
To 15 kg of water, add 2.23 kg of niobic acid having a Nb ₂ O ₅ content of 76% by weight and 4.33 kg of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] and stir to 60 ° C. with stirring. After heating and dissolving, the mixture was cooled at 30 ° C. and 8.65 kg of 5 wt% hydrogen peroxide water was added to obtain a niobium raw material liquid (B). The concentration of Nb was 0.422 mol / kg.

<Catalyst preparation>
A silica-supported oxide catalyst having a composition formula of Mo ₁ V _0.35 Sb _0.27 Nb _0.18 O _n / SiO ₂ (40 wt%) was prepared as follows.
To 1000 g of water, 250 g of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 57.9 g of ammonium metavanadate [NH ₄ VO ₃ ], antimony (III) oxide (Sb ₂ O ₃ ) 55. 7 g was added, and the reaction was carried out by refluxing in the atmosphere at 100 ° C. for 2 hours using an oil bath, followed by cooling to 50 ° C., followed by addition of 752 g of silica sol having a silica content of 30% by weight. After stirring for 30 minutes, 260 g of 5% by weight hydrogen peroxide water was added, and the mixture was stirred at 50 ° C. for 1 hour to carry out oxidation treatment to obtain a mixed solution (A). This oxidation treatment changed the liquid color from dark blue to brown.
604 g of the niobium raw material liquid (B) was added to the mixed liquid (A) and stirred at 50 ° C. for 30 minutes in an air atmosphere to obtain a catalyst raw material liquid. The obtained catalyst raw material liquid was dried under conditions of an inlet temperature of 230 ° C. and an outlet temperature of 120 ° C. using a centrifugal spray dryer to obtain a fine spherical dry powder. 100 g of the obtained dry powder was filled into a quartz container, placed in a furnace, and while rotating the container, 600 Ncc / min. Was then calcined at 620 ° C. for 2 hours under a nitrogen gas flow to obtain an oxide catalyst. The oxygen concentration of the nitrogen gas used was 1 ppm as a result of measurement using a trace oxygen analyzer (306WA type, manufactured by Teledyne Analytical Instruments Inc., USA).

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
W = 0.35 g of silica-supported oxide catalyst is packed in a fixed bed type reaction tube having an inner diameter of 4 mm, reaction temperature T = 440 ° C., propane: ammonia: oxygen: helium molar ratio = 1: 1.2: 2. A raw material mixed gas of 8: 10.6 was allowed to flow at a flow rate F = 4.1 (ml / min). At this time, the pressure P was 0 MPa as a gauge pressure. The contact time is 2.0 (g · sec / ml). Analysis of the reaction gas was performed by on-line gas chromatography. The obtained results are shown in Table 1.

[Comparative Example 1]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.34 Sb 0.31 Nb 0.12} O n as follows.
An oxide catalyst was prepared by repeating the catalyst preparation of Example 1 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Example 2]
<Catalyst preparation>
Composition formula was prepared by the silica-supported oxide catalyst represented by _{Mo 1 V 0.35 Sb 0.31 Nb 0.15} O n / SiO 2 (40 wt%) as follows.
In the preparation of the mixed solution (A), the addition amount of antimony (III) oxide was changed from 55.7 g to 64.0 g, the addition amount of 5 wt% hydrogen peroxide water to 260 g, and the addition amount of silica sol from 752 g to 770 g. Then, the catalyst preparation of Example 1 was repeated except that 604 g of the niobium raw material liquid (B) was changed to 503 g to prepare a silica-supported oxide catalyst.

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
The obtained silica-supported oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Comparative Example 2]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.35 Sb 0.31 Nb 0.15} O n as follows.
An oxide catalyst was prepared by repeating the catalyst preparation of Example 2 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 2. The obtained results are shown in Table 1.

[Example 3]
<Catalyst preparation>
A silica-supported oxide catalyst having a composition formula of Mo ₁ V _0.34 Sb _0.31 Nb _0.12 O _n / SiO ₂ (40 wt%) was prepared as follows.
In the preparation of the mixed solution (A), 57.9 g of ammonium metavanadate was added to 56.3 g, 55.7 g of antimony (III) oxide was added to 64.0 g, and 5 wt% hydrogen peroxide water was added. The silica-supported oxide catalyst was prepared by repeating the catalyst preparation of Example 1 except that the amount of 260 g was changed to 299 g, the amount of silica sol added 752 g was changed to 742 g, and the niobium raw material liquid (B) 604 g was changed to 402 g. .

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
The obtained silica-supported oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Comparative Example 3]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.34 Sb 0.31 Nb 0.12} O n as follows.
An oxide catalyst was prepared by repeating the catalyst preparation of Example 3 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 3. The obtained results are shown in Table 1.

[Example 4]
<Catalyst preparation>
A silica-supported oxide catalyst having a composition formula of Mo ₁ V _0.29 Sb _0.27 Nb _0.09 O _n / SiO ₂ (40 wt%) was prepared as follows.
In the preparation of the mixed solution (A), 57.9 g of ammonium metavanadate was added to 56.3 g, 55.7 g of antimony (III) oxide was added to 64.0 g, and 5 wt% hydrogen peroxide water was added. The catalyst preparation of Example 1 was repeated to prepare a silica-supported oxide catalyst, except that the amount 260 g was changed to 299 g, the addition amount 752 g of silica sol was changed to 742 g, and the niobium raw material liquid (B) 604 g was changed to 402 g. .

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
The obtained silica-supported oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Comparative Example 4]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.29 Sb 0.27 Nb 0.09} O n as follows.
An oxide catalyst was prepared by repeating the catalyst preparation of Example 4 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 4. The obtained results are shown in Table 1.

[Example 5]
<Catalyst preparation>
A silica-supported oxide catalyst having a composition formula of Mo ₁ V _0.31 Sb _0.30 Nb _0.15 O _n / SiO ₂ (40 wt%) was prepared as follows.
In the preparation of the mixture (A), 57.9 g of ammonium metavanadate was added to 51.3 g, and 55.7 g of antimony (III) oxide was added to 61.9 g. The silica-supported oxide catalyst was prepared by repeating the catalyst preparation of Example 1 except that the amount 260 g was changed to 288 g, the amount of silica sol 752 g was changed to 742 g, and the niobium raw material liquid (B) 604 g was changed to 503 g. .

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
The obtained silica-supported oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Comparative Example 5]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.31 Sb 0.30 Nb 0.15} O n as follows.
The oxide catalyst was prepared by repeating the catalyst preparation of Example 5 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 5. The obtained results are shown in Table 1.

[Example 6]
<Catalyst preparation>
Composition formula was prepared by the silica-supported oxide catalyst represented by _{Mo 1 V 0.29 Sb 0.31 Nb 0.14} O n / SiO 2 (40 wt%) as follows.
In the preparation of the mixed solution (A), 57.9 g of ammonium metavanadate was added to 48.0 g, 55.7 g of antimony (III) oxide was added to 63.9 g, and 5 wt% hydrogen peroxide water was added. The catalyst preparation of Example 1 was repeated to prepare a silica-supported oxide catalyst, except that the amount 260 g was changed to 298 g, the amount of silica sol 752 g was changed to 736 g, and the niobium raw material liquid (B) 604 g was changed to 469 g. .

<Measurement result of XRD>
It had diffraction peaks at 7.8 °, 8.9 °, 22.1 °, 27.1 °, 35.2 °, and 45.2 °.

<Propane Ammoxidation Test>
The obtained silica-supported oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 1. The obtained results are shown in Table 1.

[Comparative Example 6]
<Catalyst preparation>
Composition formula was prepared oxide catalyst represented by _{Mo 1 V 0.29 Sb 0.31 Nb 0.14} O n as follows.
An oxide catalyst was prepared by repeating the catalyst preparation of Example 6 except that no silica sol was used.

<Propane Ammoxidation Test>
The obtained oxide catalyst was subjected to a propane ammoxidation test under the same conditions as in Example 6. The obtained results are shown in Table 1.

  According to the present invention, in producing an unsaturated nitrile by a gas-phase catalytic ammoxidation reaction of propane or isobutane, or an unsaturated carboxylic acid by a gas-phase catalytic oxidation reaction of propane or isobutane, the requirements for a fluidized bed catalyst are provided. In addition, it is possible to provide a catalyst having a good yield and selectivity of unsaturated nitrile or unsaturated carboxylic acid, although the molybdenum content is relatively small as compared with the conventional one.

Claims (3)

A silica-supported oxide catalyst used for the production of an unsaturated nitrile by a gas phase catalytic ammoxidation reaction of propane or isobutane, or for the production of an unsaturated carboxylic acid by a gas phase catalytic oxidation reaction of propane or isobutane,
The oxide catalyst includes a component composition represented by the general formula (I),
_{Mo 1 V a Sb b Nb c} O n (I)
(Wherein a, b, c and n represent the atomic ratio per Mo atom, and n is an atomic ratio determined by the oxidation state of the constituent metals.)
In an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, diffraction angles (2θ) are 7.8 ± 0.3 °, 8.9 ± 0.3 °, 22.1 ± 0.3 °, 27. In oxide catalysts having diffraction peaks at positions of 1 ± 0.3 °, 35.2 ± 0.3 ° and 45.2 ± 0.3 °, a, b and c are represented by the formulas (II) to (V) Is the value indicated by
(II) 0.28 ≦ a ≦ 0.30 and 0.26 ≦ b ≦ 0.28 and 0.08 ≦ c ≦ 0.10;
(III) 0.28 ≦ a ≦ 0.30, 0.29 ≦ b ≦ 0.32, and 0.11 ≦ c ≦ 0.15, a <b;
(IV) 0.30 <a ≦ 0.33 and 0.27 ≦ b ≦ 0.31 and 0.08 ≦ c ≦ 0.17;
(V) 0.33 <a ≦ 0.36, 0.25 <b ≦ 0.32, and 0.08 ≦ c ≦ 0.20;
The oxide catalyst is supported on 30-55 wt% silica,
A silica-supported oxide catalyst.   The silica-supported oxide catalyst is produced by calcining a dry powder obtained from a catalyst raw material liquid having a component of a silica-supported oxide catalyst in a gas atmosphere substantially free of oxygen at 500 to 700 ° C. The silica-supported oxide catalyst according to claim 1. A method for producing an unsaturated carboxylic acid or an unsaturated nitrile by a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction of an alkane,
A method for producing an unsaturated carboxylic acid or unsaturated nitrile, comprising a step of bringing the alkane into contact with the silica-supported oxide catalyst according to claim 1 or 2.