JP5895546B2 - Composite oxide catalyst and method for producing conjugated diene - Google Patents

Description

  The present invention relates to a composite oxide catalyst used when producing a conjugated diene from a monoolefin having 4 or more carbon atoms by a gas phase catalytic oxidative dehydrogenation reaction.

A method for producing a conjugated diene such as butadiene by subjecting a monoolefin such as n-butene to an oxidative dehydrogenation reaction in the presence of a catalyst is conventionally known.
This reaction proceeds, for example, according to the following reaction formula, and water is by-produced.
C ₄ H ₈ + 1 / 2O ₂ → C ₄ H ₆ + H ₂ O
The production of butadiene by vapor-phase catalytic oxidative dehydrogenation of n-butene is industrially a C ₄ fraction produced as a by-product of naphtha cracking (C ₄ hydrocarbon mixture, hereinafter sometimes referred to as “BB”). In the process of extracting and separating butadiene from styrene, a mixture containing 1-butene, 2-butene, butane and the like obtained by separating butadiene in an extractive distillation column (hereinafter, this mixture may be referred to as “BBSS”). There is a process for producing butadiene from butene contained therein.

  As a catalyst used for butadiene production by the gas phase catalytic oxidative dehydrogenation reaction of this butene, it is known that a composite oxide catalyst mainly composed of molybdenum (Mo) and bismuth (Bi) is an effective catalyst, For example, in Patent Document 1, as a composite oxide catalyst for producing butadiene by vapor-phase catalytic oxidative dehydrogenation of n-butene with molecular oxygen, at least one of molybdenum, iron, nickel or cobalt and silica are essential components. A method for producing a composite oxide catalyst is described. Patent Document 2 contains molybdenum (Mo), bismuth (Bi), and iron (Fe) as essential components, and is selected from nickel (Ni) and cobalt (Co) as other essential components. One or more elements, one or more elements selected from the group consisting of potassium (K), rubidium (Rb) and cesium (Cs) and silica are contained, and the content of the silica component in the catalyst is 3 to 10 weights % Composite oxide catalyst is described.

  Patent Document 3 describes a method for producing butadiene by vapor-phase catalytic oxidative dehydrogenation of butene, and performs the reaction while controlling the rate of change of the outer diameter of the solid catalyst before and after the oxidative dehydrogenation reaction within a certain range. It is described.

JP 2003-220335 A JP 2011-178719 A JP 2011-241208 A

It is described that the composite oxide catalyst described in Patent Document 3 contains at least one of molybdenum, iron, nickel, or cobalt as an essential component, and may or may not contain silica. However, in the actual preparation of the composite oxide catalyst (Production Example 1), only an example in which a catalyst containing silica as an essential component was prepared is described.
According to studies by the present inventors, gas phase catalytic oxidative dehydration using a composite oxide catalyst containing silica as an essential component described in Production Example 1 of Patent Document 1, Patent Document 2, and Patent Document 3 It has been found that when butadiene is produced from butene by elementary reaction, the yield of butadiene is not sufficient.
The present invention has been made in view of the above problems, and is a composite oxide catalyst for producing a conjugated diene such as butadiene by a gas phase catalytic oxidative dehydrogenation reaction of a monoolefin such as n-butene. It is an object of the present invention to provide a composite oxide catalyst that can obtain a yield and can stably maintain high activity even when butadiene is produced on an industrial scale.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have developed a composite oxide catalyst mainly composed of molybdenum (Mo) and bismuth (Bi) for producing butadiene by vapor-phase catalytic oxidative dehydrogenation of butene. When used as a catalyst, it was found that the correlation between the acid amount and the selectivity for butadiene was stronger than the correlation between the acid amount in the composite oxide catalyst and the catalytic activity. And the amount of acids in the conventional composite oxide catalyst is reduced, and a composite oxide catalyst having a proportion lower than the silica content in the conventional composite oxide catalyst or a composite oxide catalyst not containing silica is obtained. The inventors have found that the yield of butadiene can be drastically improved and the activity can be maintained as compared with the case where a conventional composite oxide catalyst is used.

That is, the gist of the present invention resides in [1] to [ 6 ].
[1] used for manufacturing a conjugated diene by vapor-phase catalytic oxidative dehydrogenation reaction from a mixed gas containing 4 or more carbon atoms of the mono-olefin and oxygen, represented by the SL composition formula (1),且one acid the amount is a 0.01 mol / kg or less der Ru method of manufacturing a double focus oxide catalyst,
The catalyst heat-treats a raw material compound aqueous solution containing at least one compound selected from the group consisting of a molybdenum compound, an iron compound, and a nickel compound and a cobalt compound or a dried product obtained by drying the raw material compound aqueous solution. Prepared by a pre-process for preparing a catalyst precursor, and a post-process for integrating the catalyst precursor, the molybdenum compound and the bismuth compound together with an aqueous solvent, drying and firing,
Molybdenum used in the previous step is molybdenum corresponding to a partial atomic ratio (a ₁ ) of the total atomic ratio (a) of molybdenum, and the molybdenum used in the subsequent step is the total atomic ratio of molybdenum ( A method for producing a composite oxide catalyst, which is molybdenum corresponding to the remaining atomic ratio (a ₂ ) obtained by subtracting (a ₁ ) from a) .

_{Mo a Bi b Co c Ni d} Fe e X f Y g Z h Si i O j (1)
Wherein X is at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), zinc (Zn), cerium (Ce) and samarium (Sm), and Y is sodium (Na) , Potassium (K), rubidium (Rb), and thallium (Tl), at least one element selected from the group consisting of boron (B), phosphorus (P), arsenic (As), and tungsten (W) And a to j represent atomic ratios of the respective elements, and when a = 12, b = 0.1-1, c = 0-10, d. = 0 to 10 (provided c + d = 1 to 10), e = 0.05 to 3, f = 0 to 2, g = 0.04 to 2, h = 0 to 3, i = 0 to 20 And j is a numerical value that satisfies the oxidation state of other elements.)
[2] The atomic ratio (a ₁ ) is a value satisfying 0.5 <a ₁ / (c + d + e) <3, and the atomic ratio (a ₂ ) is a value satisfying 0 <a ₂ / b <8 The method for producing a composite oxide catalyst according to [1], wherein
[ 3 ] In the composition formula (1), when a = 12, b = 0.1-2, The method for producing a composite oxide catalyst according to [1] or [2] .

[ 4 ] The method for producing a composite oxide catalyst according to any one of [1] to [3] , wherein the monoolefin having 4 or more carbon atoms is butene, and the conjugated diene is butadiene.
[ 5 ] The method for producing a composite oxide catalyst according to any one of [1] to [ 4 ] , wherein the catalyst has a specific surface area of 20 m ² / g or less.
[ 6 ] Using the composite oxide catalyst obtained by the method according to any one of [1] to [ 5 ], a gas phase catalytic oxidative dehydrogenation reaction is performed from a mixed gas containing a monoolefin having 4 or more carbon atoms and oxygen. A method for producing a conjugated diene , comprising producing a conjugated diene.

  According to the present invention, when a conjugated diene such as butadiene is produced by catalytic oxidative dehydrogenation of a monoolefin having 4 or more carbon atoms such as n-butene, the conjugated diene can be produced with high yield and high selectivity. .

The present invention will be described in detail below.
[Composite oxide catalyst]
The composite oxide catalyst of the present invention is represented by the following general composition formula (1) and has an acid amount of 0.010 mol / kg or less.
_{Mo a Bi b Co c Ni d} Fe e X f Y g Z h Si i O j (1)
Wherein X is at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), zinc (Zn), cerium (Ce) and samarium (Sm), and Y is sodium (Na) , Potassium (K), rubidium (Rb), and thallium (Tl), at least one element selected from the group consisting of boron (B), phosphorus (P), arsenic (As), and tungsten (W) And a to j represent atomic ratios of the respective elements, and when a = 12, b = 0.1-1, c = 0-10, d. = 0 to 10 (provided c + d = 1 to 10), e = 0.05 to 3, f = 0 to 2, g = 0.04 to 2, h = 0 to 3, i = 0 to 20 And j is a numerical value that satisfies the oxidation state of other elements.)

  In addition, this composite oxide catalyst is a method of manufacturing through a step of heating the source compounds of the component elements constituting the composite oxide catalyst by integrating them in an aqueous system, and the molybdenum oxide, iron compound, nickel A pre-process for producing a catalyst precursor by heat-treating at least one selected from the group consisting of a compound and a cobalt compound and, if necessary, a raw material compound aqueous solution containing silica or a dried product obtained by drying the same, and the catalyst It is preferable that the precursor, the molybdenum compound and the bismuth compound are produced by a method having a post-process in which the precursor, the molybdenum compound and the bismuth compound are integrated with an aqueous solvent, and dried and fired.

Next, a method for producing a composite oxide catalyst suitable for the present invention will be described.
In this method for producing a composite oxide catalyst, the molybdenum used in the preceding step is molybdenum corresponding to a partial atomic ratio (a ₁ ) of the total atomic ratio (a) of molybdenum, The molybdenum used is molybdenum corresponding to the remaining atomic ratio (a ₂ ) obtained by subtracting a ₁ from the total atomic ratio (a) of molybdenum. The a ₁ is preferably a value satisfying 0.5 <a ₁ / (c + d + e) <3. Furthermore, it is preferable that a ₂ is a value satisfying 0 <a ₂ / b <8.

  Further, in the production of the composite oxide catalyst of the present invention, the amount of bismuth (Bi) added is such that b = 0.1-7 when a = 12, but preferably b = 0. 1-2 is added, more preferably b = 0.2 to 1.5, and even more preferably b = 0.3 to 1.0. At this time, when b exceeds 7, the selectivity of the conjugated diene tends to decrease. On the other hand, when b is less than 0.1, the butene conversion tends to decrease.

  Y is not particularly limited as long as it is at least one element selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), and thallium (Tl), but sodium (Na) and / or potassium ( Preferably, K) is included. By including sodium (Na) and / or potassium (K) in the Y component, the butadiene selectivity can be increased without reducing the activity. Y is added so that g = 0.04-2 when a = 12.

The addition amount of silica (Si) is added so that i = 0 to 20 when a = 12, but preferably i = 0 to 15, and more preferably i = 0 to 2. To be added. When i exceeds 20, the acid amount of the obtained composite oxide catalyst tends to increase, and the selectivity of butadiene tends to decrease accordingly.
Examples of the component element source compounds include oxides, nitrates, carbonates, ammonium salts, hydroxides, carboxylates, ammonium carboxylates, ammonium halides, hydrogen acids, acetyl acetates, alkoxides, etc. Specific examples thereof include the following.

Examples of Mo supply source compounds include ammonium paramolybdate, molybdenum trioxide, molybdic acid, ammonium phosphomolybdate, and phosphomolybdic acid.
Examples of Fe source compounds include ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate.
Examples of the Co source compound include cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt carbonate, and cobalt acetate. The supply amount of Co is supplied so that c = 0 to 10 when a = 12.

Examples of the Ni source compound include nickel nitrate, nickel sulfate, nickel chloride, nickel carbonate, nickel acetate and the like. The supply amount of Ni is supplied so that d = 0 to 10 when a = 12. However, it is adjusted so that c + d = 1 to 10.
Examples of Si source compounds include silica, granular silica, colloidal silica, and fumed silica.

Examples of Bi source compounds include bismuth chloride, bismuth nitrate, bismuth oxide, and bismuth subcarbonate.
Bi and X in which X component (one or more of Mg, Ca, Zn, Ce, and Sm) and Y component (one or more of Na, K, Rb, and Tl) are dissolved It can also be supplied as a composite carbonate compound with the component and the Y component. The supply amount of the X component is supplied so that f = 0 to 2 when a = 12.

For example, when Na is used as the Y component, a complex carbonate compound of Bi and Na is obtained by dropping an aqueous solution of a water-soluble bismuth compound such as bismuth nitrate into an aqueous solution of sodium carbonate or sodium bicarbonate. The precipitate can be produced by washing with water and drying.
In addition, the complex carbonate compound of Bi and the X component is prepared by mixing an aqueous solution of a water-soluble compound such as bismuth nitrate and nitrate of the X component with an aqueous solution of ammonium carbonate or ammonium bicarbonate, etc. It can be produced by washing with water and drying.

When sodium carbonate or sodium bicarbonate is used instead of the above ammonium carbonate or ammonium bicarbonate, a complex carbonate compound with Bi, Na and X components can be produced.
Examples of source compounds of other component elements include the following.
Examples of the source compound for K include potassium nitrate, potassium sulfate, potassium chloride, potassium carbonate, and potassium acetate.

Examples of Rb source compounds include rubidium nitrate, rubidium sulfate, rubidium chloride, rubidium carbonate, and rubidium acetate.
Examples of Tl source compounds include thallium nitrate, thallium chloride, thallium carbonate, and thallium acetate.
Examples of the source compound for B include borax, ammonium borate, and boric acid.

P source compounds include ammonium phosphomolybdate, ammonium phosphate, phosphoric acid, phosphorus pentoxide and the like.
As a source compound of As, dialseno 18 ammonium molybdate, dialseno 18 ammonium tungstate, etc. are mentioned.
Examples of the source compound for W include ammonium paratungstate, tungsten trioxide, tungstic acid, and phosphotungstic acid.

Examples of the Mg source compound include magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium carbonate, and magnesium acetate.
Examples of the source compound for Ca include calcium nitrate, calcium sulfate, calcium chloride, calcium carbonate, and calcium acetate.
Examples of the Zn source compound include zinc nitrate, zinc sulfate, zinc chloride, zinc carbonate, and zinc acetate.

Examples of the Ce source compound include cerium nitrate, cerium sulfate, cerium chloride, cerium carbonate, and cerium acetate.
Examples of Sm source compounds include samarium nitrate, samarium sulfate, samarium chloride, samarium carbonate, and samarium acetate.
The raw material compound aqueous solution used in the previous step is an aqueous solution, water slurry or cake containing at least molybdenum (corresponding to a ₁ in the total atomic ratio a), iron, nickel and cobalt as a catalyst component. In addition, this aqueous solution, water slurry, or cake may contain the silica as needed.

  The raw material compound aqueous solution is prepared by integrating the source compound in an aqueous system. Here, the integration of each component element source compound in an aqueous system means that the aqueous solution or aqueous dispersion of each component element source compound is mixed or / and aged in stages. Say. (B) a method of mixing the above-mentioned source compounds in a lump, (b) a method of mixing the above-mentioned source compounds in a lump and aging, and (c) a method of mixing each of the above-mentioned source compounds. Supply of each component element is a method of stepwise mixing, (d) a method of repeatedly mixing and aging the above-mentioned source compounds stepwise, and a method of combining (b) to (d). It is included in the concept of integration of the source compound in an aqueous system. Here, aging refers to the processing of industrial raw materials or semi-finished products under specific conditions such as constant temperature for a certain period of time to obtain the required physical and chemical properties, increase or advance the prescribed reaction, etc. The fixed time is usually in the range of 10 minutes to 24 hours, and the fixed temperature is usually in the range of room temperature to the boiling point of the aqueous solution or aqueous dispersion.

  As a specific method of the above integration, for example, a solution obtained by mixing an acidic salt selected from catalyst components, and a solution obtained by mixing a basic salt selected from catalyst components, Specific examples include a method in which a mixture of an iron compound, a nickel compound and a cobalt compound is added to an aqueous solution of a molybdenum compound while heating. In addition, it is preferable to perform addition and mixing of silica in this previous step as required.

The raw material compound aqueous solution (slurry) thus obtained is heated to 60 to 90 ° C. and aged.
This aging refers to stirring the catalyst precursor slurry at a predetermined temperature for a predetermined time. This aging increases the viscosity of the slurry, reduces the sedimentation of the solid components in the slurry, and is particularly effective in suppressing the heterogeneity of components in the subsequent drying process. The catalytic activity such as the raw material conversion rate and selectivity of the product catalyst becomes better.

  60-90 degreeC is preferable and the temperature in the said ripening has more preferable 70-85 degreeC. When the aging temperature is less than 60 ° C., the aging effect is not sufficient, and good activity may not be obtained. On the other hand, when the temperature exceeds 90 ° C., water is often evaporated during the aging time, which is disadvantageous for industrial implementation. Further, if the temperature exceeds 100 ° C., a pressure vessel is required for the dissolution tank, and handling becomes complicated, which is extremely disadvantageous in terms of economy and operability.

The aging time is preferably 2 to 12 hours, and preferably 3 to 8 hours. If the aging time is less than 2 hours, the activity and selectivity of the catalyst may not be sufficiently developed. On the other hand, the aging effect does not increase even if it exceeds 12 hours, which is disadvantageous for industrial implementation.
Any method can be adopted as the stirring method, and examples thereof include a method using a stirrer having a stirring blade and a method using external circulation using a pump.

  The aged slurry is subjected to heat treatment as it is or after drying. There is no particular limitation on the drying method in the case of drying and the state of the dried product to be obtained. For example, a powdery dried product may be obtained using a normal spray dryer, slurry dryer, drum dryer, etc. Alternatively, a block-shaped or flake-shaped dried product may be obtained using a normal box-type dryer or a tunnel-type firing furnace.

  The raw material salt aqueous solution or granules or cakes obtained by drying the aqueous salt solution are heat-treated in air at a temperature of 200 to 400 ° C, preferably 250 to 350 ° C. There are no particular limitations on the type and method of the furnace at that time, and for example, it may be heated with a dry matter fixed using a normal box-type furnace, tunnel-type furnace, etc., or a rotary kiln. It is possible to heat the dried product while flowing it.

In the step after the, the integration of the above procatalyst precursor and the molybdenum compound obtained in step (remaining a ₂ corresponds to minus a ₁ equivalent of the total atomic ratio a) and bismuth compounds, carried out in an aqueous solvent . At this time, it is preferable to add ammonia water. It is preferable to add the X, Y, and Z components in the subsequent steps. These compounds as the catalyst production raw material may be particles larger than the powder, but are preferably smaller particles in view of the heating step in which thermal diffusion should be performed. Therefore, if these compounds as raw materials are not such particles, they should be pulverized before the heating step.

  Next, the obtained slurry is sufficiently stirred and then dried. The dried product thus obtained is shaped into an arbitrary shape by a method such as extrusion molding, tableting molding or support molding. The size of the catalyst shaped into these types of shapes can be appropriately changed to a size corresponding to the reaction mode such as a fixed bed or a fluidized bed. Next, this is preferably subjected to a final heat treatment for about 1 to 16 hours under a temperature condition of 450 to 650 ° C. As described above, a composite oxide catalyst that is highly active and gives the target conjugated diene in high yield can be obtained.

The composite oxide catalyst thus obtained is usually packed in a reactor together with an inert ball for adjusting the reaction activity to form a fixed bed.
As the inert ball, a ceramic spherical body such as alumina or zirconia is used. The inert ball is usually the same size as the composite oxide catalyst, and its particle size is about 2 to 10 mm.

The specific surface area of the composite oxide catalyst of the present invention, BET 1-point method: When measuring the (adsorbed gas nitrogen) is preferably 2 to 20 m ² / g, more preferably from 3~15m ² / g. The larger the value, the higher the activity of the catalyst, and the smaller the value, the lower the selectivity due to the sequential reaction.
The acid amount of the composite oxide catalyst of the present invention is 0.010 mol / kg or less, preferably 0.008 mol / kg or less, when measured by a temperature programmed desorption method (probe molecule: pyridine). As this value is smaller, side reactions such as combustion can be suppressed.
The acid amount of the composite oxide catalyst of the present invention can be adjusted by the amount of silica added. By reducing the amount of silica added, an increase in the amount of acid can be suppressed.

[Conjugate diene production method]
The method for producing a conjugated diene according to the present invention comprises 4 or more carbon atoms such as butene (n-butene such as 1-butene and / or 2-butene, isobutene), pentene, methylbutene, dimethylbutene, etc., preferably 4 carbon atoms. It can be effectively applied to the production of the corresponding conjugated diene by catalytic oxidative dehydrogenation of monoolefins of ˜6. Among these, it is most suitably used for the production of butadiene from butene and further from n-butene (1-butene and / or 2-butene).

The raw material gas of the present invention contains a monoolefin having 4 or more carbon atoms, but it is not necessary to use an isolated monoolefin having 4 or more carbon atoms as the raw material gas, and any mixture can be used as necessary. Can be used. For example, in order to obtain butadiene, high-purity n-butene (1-butene and / or 2-butene) can be used as a raw material gas, but the C ₄ fraction by-produced by the above-described naphtha decomposition ( A butene fraction containing n-butene (1-butene and / or 2-butene) obtained by separating butadiene and isobutene from BB) can also be used. Further, a gas containing high-purity 1-butene, cis-2-butene, trans-2-butene or a mixture thereof obtained by dimerization of ethylene may be used as a raw material gas. As the ethylene, ethylene obtained by a method such as ethane dehydrogenation, ethanol dehydration, or naphtha decomposition can be used. Furthermore, fluid catalytic cracking (Fluid Catalytic Cracking), in which a heavy oil fraction obtained by distilling crude oil in an oil refinery plant or the like is decomposed in a fluidized bed state using a powdered solid catalyst and converted into low-boiling hydrocarbons. ) Gas containing a large number of hydrocarbons having 4 carbon atoms obtained from (hereinafter sometimes abbreviated as FCC-C4) as it is, or removing impurities such as phosphorus and arsenic from FCC-C4 It is possible to use the raw material as a raw material gas. The main component here is usually 40% by volume or more, preferably 60% by volume or more, more preferably 75% by volume or more, and particularly preferably 99% by volume or more with respect to the raw material gas.

  In addition, the source gas of the present invention may contain an arbitrary impurity as long as the effects of the present invention are not impaired. When producing butadiene from n-butene (1-butene and / or 2-butene), as impurities that may be included, specifically, branched monoolefins such as isobutene; propane, n-butane, isobutane, Saturated hydrocarbons such as pentane; olefins such as propylene and pentene; dienes such as 1,2-butadiene; acetylenes such as methyl acetylene, vinyl acetylene and ethyl acetylene. The amount of this impurity is usually 40% by volume or less, preferably 20% by volume or less, more preferably 10% by volume or less, and particularly preferably 1% by volume or less. If the amount is too large, the concentration of 1-butene or 2-butene, which are the main raw materials, decreases and the reaction becomes slow, or the yield of the target product tends to decrease.

The molecular oxygen-containing gas of the present invention is usually a gas containing 10% by volume or more of molecular oxygen, preferably 15% by volume or more, more preferably 20% by volume or more, and specifically preferably air. It is. From the viewpoint of cost required for industrially preparing a molecular oxygen-containing gas, the molecular oxygen is usually 50% by volume or less, preferably 30% by volume or less, more preferably 25% by volume or less. . Moreover, the molecular oxygen-containing gas may contain an arbitrary impurity as long as the effects of the present invention are not impaired. Specific examples of impurities that may be included include nitrogen, argon, neon, helium, CO, CO ₂ , and water. In the case of nitrogen, the amount of this impurity is usually 90% by volume or less, preferably 85% by volume or less, more preferably 80% by volume or less. In the case of components other than nitrogen, it is usually 10% by volume or less, preferably 1% by volume or less. When this amount is too large, it tends to be difficult to supply oxygen necessary for the reaction.

In the present invention, when supplying the raw material gas to the reactor, a mixed gas containing the raw material gas and oxygen is supplied to the reactor. However, together with the mixed gas, nitrogen gas and water (water vapor) may be supplied to the reactor. Good. Because nitrogen gas adjusts the concentration of combustible gas and oxygen so that the mixed gas does not enter the combustion range, water (steam) adjusts the concentration of combustible gas and oxygen in the same way as nitrogen gas And water (steam) in the mixed gas because it suppresses coking of the catalyst
It is preferable to further mix and nitrogen gas and supply to the reactor.

  The concentration of monoolefin in the mixed gas supplied to the reactor (raw gas, molecular oxygen-containing gas, nitrogen gas, and water (water vapor)) is not particularly limited, but is usually 1 to 20 vol%, preferably 3 to 17 vol%. More preferably, it is 6-13 vol%. The higher the monoolefin concentration, the lower the cost of recovering the corresponding conjugated diene, and the lower the monoolefin, there is the advantage that side reactions such as polymerization and combustion hardly occur.

  Further, the method of supplying the source gas, the molecular oxygen-containing gas, the nitrogen gas, and water (water vapor) is not particularly limited, and may be supplied by separate pipes, but the formation of the blast is surely avoided. Therefore, before obtaining the mixed gas, nitrogen gas is supplied to the source gas in advance, or nitrogen gas is supplied to the molecular oxygen-containing gas, and in this state, the source gas and the molecular oxygen-containing gas are supplied. Is preferably mixed to obtain a mixed gas.

  The reactor used for the oxidative dehydrogenation reaction of the present invention is not particularly limited, and specific examples include a tubular reactor, a tank reactor, or a fluidized bed reactor, preferably a fixed bed reactor, More preferred are fixed bed multitubular reactors and plate reactors, and most preferred is a fixed bed multitubular reactor.

  When the reactor is a fixed bed reactor, the reactor has a catalyst layer having the above-described oxidative dehydrogenation reaction catalyst. The catalyst layer may be composed of a layer composed only of the catalyst, or may be composed only of a layer containing a catalyst and a solid that is not reactive with the catalyst, or a solid that is not reactive with the catalyst and the catalyst. The catalyst layer may include a layer containing a catalyst and a layer containing only a catalyst, but the catalyst layer includes a layer containing a catalyst and a solid that is not reactive with the catalyst. Therefore, it is preferable to have a solid material having no reactivity in the catalyst layer.

  The oxidative dehydrogenation reaction of the present invention is an exothermic reaction, and the temperature rises due to the reaction. In the present invention, the reaction temperature is usually adjusted to 250 to 450 ° C, preferably 280 to 400 ° C. As the temperature increases, the catalytic activity tends to decrease rapidly, and as the temperature decreases, the yield of the conjugated diene that is the target product tends to decrease. The reaction temperature can be controlled using a heat medium (for example, dibenzyltoluene or nitrite). In addition, the reaction temperature here is the temperature of a heat medium.

  Moreover, the reactor internal temperature in this invention is although it does not specifically limit, Usually, 250-450 degreeC, Preferably, it is 280-400 degreeC, More preferably, it is 320-395 degreeC. When the temperature of the catalyst layer exceeds 450 ° C., the catalytic activity tends to decrease rapidly as the reaction is continued. On the other hand, when the temperature of the catalyst layer is lower than 250 ° C., the conjugate which is the target organism. The yield of diene tends to decrease. The temperature in the reactor is determined by the reaction conditions, but can be controlled by the dilution rate of the catalyst layer, the flow rate of the mixed gas, and the like. In addition, the temperature in a reactor here is the temperature of the product gas in the exit of a reactor, or the temperature of the catalyst layer in the case of the reactor which has a catalyst layer.

The pressure in the reactor of the present invention is not particularly limited, but the upper limit is 0.5 MPaG (gauge pressure) or less, preferably 0.3 MPaG or less, more preferably 0.1 MPaG or less. As this value decreases, the explosion range tends to narrow.
The space velocity in the present invention is a value represented by the following equation.

Space velocity SV (h ⁻¹ ) = mixed gas supplied to the reactor (source gas, molecular oxygen-containing gas, nitrogen gas, and water (water vapor)) at 0 ° C., volume flow rate at 1 atm / reactor Packed catalyst volume (not including non-reactive solids)
The space velocity is not particularly limited, but the lower limit is preferably 500 h ⁻¹ or more, more preferably 1300 h ⁻¹ or more. As this value increases, there is an advantage that the amount of monoolefin in the raw material gas that can be supplied to the reactor can be increased. On the other hand, the upper limit is preferably 9000h ^-1 or less, more preferably 7500H ^-1 or less. As this value is smaller, there is an advantage that the conversion rate of the monoolefin in the raw material gas becomes higher.

The present invention will be described more specifically with reference to the following examples. In the examples, the n-butene conversion, butadiene selectivity, and butadiene yield were calculated according to the following formulas.
N-butene conversion (mol%) = (moles of reacted 1-butene + cis-2-butene + trans-2-butene) / (supplied 1-butene + cis-2-butene + trans-2) -Number of moles of butene) x 100
Butadiene selectivity (mol%) = (mol number of butadiene produced) / (mol number of reacted 1-butene + cis-2-butene + trans-2-butene) × 100
Butadiene yield (mol%) = (mol number of butadiene produced) / (mol number of supplied 1-butene + cis-2-butene + trans-2-butene) × 100

[Example 1]
(A) Preparation of Catalyst Precursor 446 g of ammonium paramolybdate was added to 4.4 L of pure water and heated to 80 ° C. to dissolve. Next, 190 g of ferric nitrate, 395 g of cobalt nitrate, and 213 g of nickel nitrate were put into 760 ml of pure water and heated to 80 ° C. to dissolve. These solutions were gradually mixed with thorough stirring.

  This slurry was heated to 80 ° C. and aged for 4 hours. Thereafter, the slurry was dried by heating and then subjected to heat treatment at 300 ° C. for 1 hour in an air atmosphere.

(B) Catalyst Preparation ammonium paramolybdate 7.83 g, potassium nitrate 0.74g of pure water 120 ml, to a solution added to a mixture of ammonia water 14 ml, was ground particulate solid of the resulting catalyst precursor in the heat treatment 191 g of the product was added and dispersed.
Next, 8.31 g of bismuth carbonate containing 0.5% Na in solid solution was added and mixed with stirring. After the slurry was heat-dried at 130 ° C. for 12 hours, the obtained granular solid was formed into tablets with a diameter of 5 mm and a height of 4 mm using a small molding machine, and then baked at 500 ° C. for 4 hours. The catalyst was obtained.
Table 1 shows the atomic ratio of the composite oxide catalyst calculated from the charged raw materials.

(C) Measurement of acid amount The measuring apparatus used the Nippon Bell Co., Ltd. make fully automatic temperature-programmed desorption spectrum apparatus TPD-1-ATw.
300 mg of the pulverized composite oxide catalyst produced above was heated to 150 ° C. under vacuum and maintained for 1 hour for pretreatment. Next, while maintaining 150 ° C., pyridine vapor was introduced into the system and adsorbed for 30 minutes. After evacuation, the complex oxide catalyst thus treated was heated from 100 ° C. to 610 ° C. at 10 ° C./min under 50 ml / min of helium, and the acid amount was measured from the desorbed pyridine spectrum. did. The results are shown in Table 1.

(D) Measurement of specific surface area The measuring apparatus used was Macsorb HM Model-1201 manufactured by Mountec.
The composite oxide catalyst produced above was pulverized, heated to 250 ° C. under nitrogen flow, and pretreated by holding for 15 minutes. Nitrogen was adsorbed to the pretreated sample at −196 ° C., and the specific surface area was measured by the BET one-point method. The results are shown in Table 1.

(E) A 1,3-butadiene production inner diameter 23.0 mm and a length of 500 mm stainless steel reaction tube were mixed with 10.0 ml of the composite oxide catalyst produced above and 10.0 ml of inert ball (Chipton). Filled.
An insertion tube having an outer diameter of 2.0 mm was installed in these reaction tubes, and a thermocouple was installed in the insertion tube to measure the temperature in the reactor. An electric furnace was used as the heat medium.
Then, 5.8 L / hr of nitrogen, 17.3 L / hr of air, and 3.0 L / hr of water vapor are supplied to the preheater in advance, and then 3.9 L of the raw material gas having the composition shown in Table 2 is supplied. / Hr, mixed in a preheater and heated to a reaction temperature of 350 ° C. as a mixed gas (reactor introduction gas composition = nitrogen: 19.2 vol%, air: 57.8 vol%, water vapor: 10.0 vol%) , Raw material gas: 13.0 vol%). Table 2 shows a typical composition (mol%) contained in the source gas. The detailed reaction conditions are shown in Table 2.
The mixed gas was supplied to the above reactor, and an oxidative dehydrogenation reaction was performed. The pressure was 2 kPa as a gauge pressure. Table 1 shows the results of analysis by gas chromatography (model number: GC-4000, manufactured by GL Science).

[Comparative Example 1]
(A) Preparation of catalyst precursor 300 g of ammonium paramolybdate was added to 3.0 L of pure water and heated to 80 ° C. to dissolve. Next, 128 g of ferric nitrate, 266 g of cobalt nitrate, and 143 g of nickel nitrate were put into 500 ml of pure water and heated to 80 ° C. to dissolve. These solutions were gradually mixed with thorough stirring.

Next, 197 g of silica was added to 890 ml of pure water, and a sufficiently mixed solution was added to the above solution and sufficiently stirred.
This slurry was heated to 80 ° C. and aged for 4 hours. Thereafter, the slurry was dried by heating and then subjected to heat treatment at 300 ° C. for 1 hour in an air atmosphere.

(B) Preparation of catalyst A composite oxide catalyst was prepared from a charged raw material having the desired composition by the same operation as in Example 1 (b), except that the catalyst precursor obtained in Comparative Example 1 (a) was used. did.
Table 1 shows the atomic ratio of the composite oxide catalyst calculated from the charged raw materials.
(C) Measurement of acid amount The acid amount was measured in the same manner as in Example 1 (c). The results are shown in Table 1.
(D) Measurement of specific surface area The specific surface area was measured by the same method as in Example 1 (d). The results are shown in Table 1.
(E) Production of 1,3-butadiene In the same manner as in Example 1 (e), 1,3-butadiene was produced using the composite oxide catalyst of Comparative Example 1. The results are shown in Table 1.

[Example 2]
(A) Preparation of catalyst 424 g of ammonium paramolybdate and 2.00 g of potassium nitrate were put into 3.0 L of pure water, and heated to 80 ° C. to dissolve. Next, 146 g of ferric nitrate, 303 g of cobalt nitrate and 163 g of nickel nitrate are put into 1000 ml of pure water, heated to 25 ° C. to dissolve, and 165 g of bismuth nitrate is put into 200 ml of pure water and 25 ml of concentrated nitric acid. The dissolved solution was mixed. These solutions were gradually mixed with thorough stirring.

This slurry was heated to 80 ° C. and aged for 4 hours. Thereafter, the slurry was dried by heating and then subjected to heat treatment at 300 ° C. for 1 hour in an air atmosphere.
The obtained granular solid was tableted and formed into a tablet having a diameter of 5 mm and a height of 4 mm with a small molding machine, and then calcined at 500 ° C. for 4 hours to obtain a catalyst.
Table 1 shows the atomic ratio of the composite oxide catalyst calculated from the charged raw materials.

(B) Measurement of acid amount The acid amount was measured in the same manner as in Example 1 (c). The results are shown in Table 1.
(C) Measurement of specific surface area The specific surface area was measured by the same method as in Example 1 (d). The results are shown in Table 1.
(D) Production of 1,3-butadiene In the same manner as in Example 1 (e), 1,3-butadiene was produced using the composite oxide catalyst of Example 2. The results are shown in Table 1.

[Example 3]
(A) Preparation of Catalyst Precursor 422 g of ammonium paramolybdate was charged into 4.2 L of pure water and heated to 80 ° C. to dissolve. Next, 179 g of ferric nitrate, 374 g of cobalt nitrate, and 201 g of nickel nitrate were put into 720 ml of pure water and heated to 80 ° C. to dissolve. These solutions were gradually mixed with thorough stirring.
Next, 25 g of silica was added to 110 ml of pure water, and a sufficiently mixed solution was added to the above solution and sufficiently stirred.
This slurry was heated to 80 ° C. and aged for 4 hours. Thereafter, the slurry was dried by heating and then subjected to heat treatment at 300 ° C. for 1 hour in an air atmosphere.

(B) Preparation of catalyst A composite oxide catalyst was prepared from a charged raw material having the desired composition by the same operation as in Example 1 (b), except that the catalyst precursor obtained in Example 3 (a) was used. did.
Table 1 shows the atomic ratio of the composite oxide catalyst calculated from the charged raw materials.
(C) Measurement of acid amount The acid amount was measured in the same manner as in Example 1 (c). The results are shown in Table 1.
(D) Measurement of specific surface area The specific surface area was measured by the same method as in Example 1 (d). The results are shown in Table 1.
(E) Production of 1,3-butadiene 1,3-butadiene was produced using the composite oxide catalyst of Example 3 in the same manner as in Example 1 (e). The results are shown in Table 1.

[Reference Example 1]
(A) Preparation of catalyst precursor 403 g of ammonium paramolybdate was put into 940 ml of pure water and heated to 80 ° C. to dissolve. Next, 18 wt% silica slurry was gradually added and mixed with stirring.
In another container, 169 g of ferric nitrate and 382 g of cobalt nitrate were put into 520 ml of pure water and dissolved at 16 ° C. These solutions were gradually mixed with thorough stirring.

Next, 19 g of bismuth nitrate was dissolved at 16 ° C. in a mixed solution of 530 ml of pure water and 46 ml of concentrated nitric acid, mixed with the above solution with sufficient stirring, and further 30 g of 50% cesium hydroxide was added to 40 ml of pure water. It melt | dissolved at 16 degreeC and stirred and mixed. Warm this slurry to 80 ° C.,
Aged for 4 hours. Thereafter, the slurry was dried by heating and then subjected to heat treatment at 300 ° C. for 1 hour in an air atmosphere.

  The obtained granular solid was tableted into a cylindrical tablet having a bottom diameter of 5 mm and a height of 4 mm with a small molding machine, and then calcined at 500 ° C. for 4 hours to obtain a solid catalyst. The catalyst calculated from the charged raw materials was a complex oxide having the following atomic ratio. Mo: Bi: Co: Ni: Fe: Na: K: Cs: B: Si = 12: 2.1: 6.9: 0: 2.2: 0: 0: 0.5: 0: 3

(B) Measurement of acid amount As a result of measuring the acid amount by the same method as in Example 1 (c), the acid amount was 0.006 mol / kg.
(D) Production of 1,3-butadiene 1,3-butadiene was produced using the composite oxide catalyst of Reference Example 1 in the same manner as in Example 1 (e).
n-butene conversion rate (conversion rate of 1-butene, cis-2-butene and trans-2-butene in total) was 25.5 mol%, butadiene selectivity was 85.3 mol%, and butadiene yield was 21.8 mol. %Met.

When Examples 1 to 3 are compared with Comparative Example 1, the butadiene yields of Examples 1 to 3 are higher than those of Comparative Example 1. By reducing the amount of silica added, the total acid amount is 0.00. It decreases to 010 or less, and the decrease in butadiene yield can be suppressed.
When Example 1 and Example 2 are compared, the n-butene conversion rate and butadiene selectivity of Example 1 are higher than those of Example 2, and the activity and selection are reduced by reducing the amount of bismuth added. It can be seen that there is an effect of improving the rate.

Claims (6)

Used for manufacturing a conjugated diene by vapor-phase catalytic oxidative dehydrogenation reaction from a mixed gas containing 4 or more carbon atoms of the mono-olefin and oxygen is represented by the following composition formula (1), the amount且one acid 0. A method for producing a composite oxide catalyst having a concentration of 010 mol / kg or less,
The catalyst heat-treats a raw material compound aqueous solution containing at least one compound selected from the group consisting of a molybdenum compound, an iron compound, and a nickel compound and a cobalt compound or a dried product obtained by drying the raw material compound aqueous solution. Prepared by a pre-process for preparing a catalyst precursor, and a post-process for integrating the catalyst precursor, the molybdenum compound and the bismuth compound together with an aqueous solvent , drying and firing ,
Molybdenum used in the previous step is molybdenum corresponding to a partial atomic ratio (a ₁ ) of the total atomic ratio (a) of molybdenum, and the molybdenum used in the subsequent step is the total atomic ratio of molybdenum ( A method for producing a composite oxide catalyst , which is molybdenum corresponding to the remaining atomic ratio (a ₂ ) obtained by subtracting (a ₁ ) from a).
_{Mo a Bi b Co c Ni d} Fe e X f Y g Z h Si i O j (1)
Wherein X is at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), zinc (Zn), cerium (Ce) and samarium (Sm), and Y is sodium (Na) , Potassium (K), rubidium (Rb), and thallium (Tl), at least one element selected from the group consisting of boron (B), phosphorus (P), arsenic (As), and tungsten (W) And a to j represent atomic ratios of the respective elements, and when a = 12, b = 0.1-1, c = 0-10, d. = 0 to 10 (provided c + d = 1 to 10), e = 0.05 to 3, f = 0 to 2, g = 0.04 to 2, h = 0 to 3, i = 0 to 2 And j is a numerical value that satisfies the oxidation state of other elements.) The atomic ratio (a ₁ ) is a value satisfying 0.5 <a ₁ / (c + d + e) <3, and the atomic ratio (a ₂ ) is a value satisfying 0 <a ₂ / b <8. The method for producing a composite oxide catalyst according to claim 1. 3. The method for producing a composite oxide catalyst according to claim 1, wherein in the composition formula (1), when a = 12, b = 0.1-2. The method for producing a composite oxide catalyst according to any one of claims 1 to 3, wherein the monoolefin having 4 or more carbon atoms is butene and the conjugated diene is butadiene. 5. The method for producing a composite oxide catalyst according to claim 1, wherein the catalyst has a specific surface area of 20 m ² / g or less. Using the composite oxide catalyst obtained by the method according to any one of claims 1 to 5, a gas phase catalytic oxidative dehydrogenation reaction is performed from a mixed gas containing a monoolefin having 4 or more carbon atoms and oxygen. A method for producing a conjugated diene, comprising producing a conjugated diene.