JP2011246384A - Method for producing unsaturated aldehyde and unsaturated carboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for lowering temperature of a hot spot and obtaining high selectivity and a high yield of unsaturated aldehyde and unsaturated carboxylic acid.SOLUTION: In the method for producing unsaturated aldehyde and unsaturated carboxylic acid, using a fixed bed tubular reactor filled with a catalyst, vapor phase catalytic oxidation of a raw material, which is at least one selected from the group consisting of propylene, isobutylene, TBA and MTBE, is carried out by molecular oxygen or molecular oxygen-containing gas, and the unsaturated aldehyde or the unsaturated carboxylic acid corresponding to the raw material is produced. The catalyst is a composite oxide containing at least molybdenum, bismuth and iron. A plurality of reaction zones are arranged by dividing the inside of a reaction tube in the fixed bed tubular reactor in the tube axis direction. Each of the reaction zones is filled with the catalyst so that a ratio of the pore volume within the pore diameter range of 0.1-2 μm to the pore volume within the pore diameter range of 0.1-100 μm of the catalyst is increased from the raw material inlet side to the outlet side of the reaction tube.

Description

  The present invention relates to a method for producing an unsaturated aldehyde and an unsaturated carboxylic acid. Specifically, at least selected from propylene, isobutylene, tertiary butyl alcohol (hereinafter also referred to as TBA) and methyl tertiary butyl ether (hereinafter also referred to as MTBE) using a fixed bed tubular reactor packed with a catalyst. The present invention relates to a method for producing an unsaturated aldehyde and an unsaturated carboxylic acid by gas phase catalytic oxidation using molecular oxygen or a molecular oxygen-containing gas as a raw material.

  Conventionally, using a fixed bed multitubular reactor packed with a catalyst, gas phase catalytic oxidation is performed with molecular oxygen or a molecular oxygen-containing gas using at least one compound selected from propylene, isobutylene, TBA and MTBE as a raw material. Thus, many proposals have been made regarding methods for producing the corresponding unsaturated aldehyde and unsaturated carboxylic acid.

  The oxidation reaction is usually carried out using a fixed bed multi-tubular reactor. However, since the reaction involves a large exotherm, the yield is reduced due to excessive oxidation reaction and the catalyst is deteriorated due to acceleration of catalyst deterioration. There is a problem of reduced life. Several proposals have been made to keep the hot spot temperature low and improve productivity and catalyst life.

  For example, a method is disclosed in which a plurality of catalysts having different activities prepared by changing the type and / or amount of alkaline earth metal are charged so that the activity becomes higher from the raw material gas inlet to the outlet. (Patent Document 1). In addition, the content of the inactive component in the catalyst molded body was changed, and the activity was adjusted by changing at least one of the occupied volume of the catalyst molded body, the type and / or amount of alkali metal, and the calcination temperature, A method of filling a plurality of types of catalyst molded bodies having different activities so as to increase the activity from the reaction gas inlet side to the outlet side of each reaction tube is disclosed (Patent Document 2).

  Furthermore, a plurality of reaction zones are provided by dividing the inside of each reaction tube in the fixed bed multi-tubular reactor in the tube axis direction, and a catalyst having a different ratio of the apparent density of the catalyst to the true density of the catalyst is filled. A method is disclosed (Patent Document 3). In addition, a method is disclosed in which the catalyst packed bed is divided into a plurality of reaction zones, and the catalyst is filled so that the pore sizes of the catalysts differ between the reaction zones (Patent Document 4). Further, a filling method is disclosed in which the occupied volume is different in at least two of the plurality of reaction zones, and the inert substance molded body is mixed in at least one of the plurality of reaction zones (Patent Document 5).

Japanese Patent Laid-Open No. 10-72389 JP 2001-328951 A JP 2004-2209 A JP 2004-2323 A JP 2005-320315 A

  Any of the above-described conventionally known proposals is a proposal focusing on keeping the temperature of the hot spot portion low. However, when carrying out an oxidation reaction using a fixed bed multitubular reactor, it is not possible to completely eliminate the occurrence of hot spot portions in the catalyst layer, and the degree of deterioration of the catalyst located in the hot spot portion is different from that of other portions. The problem of being relatively large compared to the degree of deterioration of the catalyst located in the region cannot be solved. In particular, this problem becomes significant when a molybdenum-based catalyst is used or when the reaction is performed at a high source gas concentration.

  Further, in the reaction of producing at least one compound selected from propylene, isobutylene, TBA and MTBE by catalytic gas phase oxidation to produce the corresponding unsaturated aldehyde and unsaturated carboxylic acid, respectively, due to the occurrence of a hot spot portion at a high temperature. Undesirable side reactions such as parallel reaction and sequential reaction are likely to occur, and the selectivity and yield of the target product are lowered. This side reaction causes an undesired transition of the catalyst to a redox state, clogging of pores, and the like, and shortens the catalyst life.

  Therefore, the present invention uses a fixed bed tubular reactor, using at least one compound selected from the group consisting of propylene, isobutylene, TBA, and MTBE as a raw material, and vapor phase contact with molecular oxygen or a molecular oxygen-containing gas. In the method of producing an unsaturated aldehyde and unsaturated carboxylic acid corresponding to the raw material by oxidation, the temperature of the hot spot part is lowered to obtain a high selectivity and yield of the unsaturated aldehyde and unsaturated carboxylic acid. The purpose is to provide a method capable of

  The method for producing an unsaturated aldehyde and an unsaturated carboxylic acid according to the present invention uses a fixed bed tubular reactor packed with a catalyst, from the group consisting of propylene, isobutylene, tertiary butyl alcohol and methyl tertiary butyl ether. In the method for producing an unsaturated aldehyde and an unsaturated carboxylic acid corresponding to a raw material by performing gas phase catalytic oxidation with molecular oxygen or a molecular oxygen-containing gas using at least one selected compound as a raw material, the catalyst comprises: A composite oxide containing at least molybdenum, bismuth and iron, and dividing the inside of the reaction tube in the fixed bed tubular reactor in the tube axis direction to provide a plurality of reaction zones, From the raw material inlet side to the outlet side, the catalyst has a pore diameter in the range of 0.1 to 2 μm with respect to the pore volume in the range of 0.1 to 100 μm. In this method, each reaction zone in the reaction tube is filled with the catalyst so that the ratio of the pore volumes becomes large.

  According to the method of the present invention, molecular oxygen or molecular oxygen-containing gas is obtained using at least one compound selected from the group consisting of propylene, isobutylene, TBA, and MTBE as a raw material using a fixed bed tubular reactor. In the method for producing an unsaturated aldehyde and unsaturated carboxylic acid corresponding to the raw material by gas phase catalytic oxidation, the temperature of the hot spot is lowered, and the selectivity and yield of the high unsaturated aldehyde and unsaturated carboxylic acid are reduced. Rate can be obtained.

  The method for producing an unsaturated aldehyde and an unsaturated carboxylic acid according to the present invention uses a fixed bed tubular reactor packed with a catalyst, from the group consisting of propylene, isobutylene, tertiary butyl alcohol and methyl tertiary butyl ether. In the method for producing an unsaturated aldehyde and an unsaturated carboxylic acid corresponding to a raw material by performing gas phase catalytic oxidation with molecular oxygen or a molecular oxygen-containing gas using at least one selected compound as a raw material, the catalyst comprises: A composite oxide containing at least molybdenum, bismuth and iron, and dividing the inside of the reaction tube in the fixed bed tubular reactor in the tube axis direction to provide a plurality of reaction zones, From the raw material inlet side to the outlet side, the catalyst has a pore diameter in the range of 0.1 to 2 μm with respect to the pore volume in the range of 0.1 to 100 μm. Each reaction zone in the reaction tube is filled with the catalyst so that the ratio of the pore volumes becomes large.

  Conventionally, in an exothermic reaction such as gas phase catalytic oxidation performed in the method according to the present invention, no attempt has been made to try to lower the temperature of the hot spot part by controlling the pore structure inside the catalyst used. In the present invention, the inventors have found a method for lowering the temperature of the hot spot portion by controlling the pore structure inside the catalyst, and further improving the selectivity and yield of the target product. Specifically, a plurality of types of catalysts having different pore structures are used, and a catalyst zone having a pore diameter of 0. 0 is formed in a reaction zone divided into a plurality in the axial direction of the reaction tube from the raw material inlet side to the outlet side. The catalyst is arranged so that the ratio of the pore volume in the range of 0.1 to 2 μm to the pore volume in the range of 1 to 100 μm is sequentially increased. That is, a reaction zone filled with the catalyst having the lowest pore volume ratio is provided on the raw material inlet side, and a reaction zone filled with the catalyst having the highest pore volume ratio is provided on the outlet side. The reaction zone is filled with a catalyst in which the pore volume ratio increases sequentially from the outlet toward the outlet. Thereby, the temperature of a hot spot part can be lowered | hung, reaction is performed safely and efficiently, and the improvement of productivity can be achieved without impairing the lifetime of a catalyst.

(Catalyst, production method of catalyst)
The catalyst used in the present invention is a composite oxide containing at least molybdenum, bismuth and iron. In particular, the catalyst preferably has a composition represented by the following formula (I).

Mo _a Bi _b Fe _c M _d X _e Y _f Z _g Si _h O _i (I)
In the formula (I), Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively. M represents at least one element selected from cobalt and nickel. X represents at least one element selected from chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc. Y represents at least one element selected from phosphorus, boron, sulfur, selenium, tellurium, cerium, tungsten, antimony and titanium. Z represents at least one element selected from lithium, sodium, potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g, h, and i represent the atomic ratio of each element. When a = 12, b = 0.01-3, c = 0.01-5, d = 1. -12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, and h = 0 to 20, i is an oxygen atomic ratio necessary for satisfying the valence of each component. is there. The composition represented by the formula (I) is a value calculated from the amount of raw material charged for each element.

  Although it does not specifically limit as a manufacturing method of the catalyst which concerns on this invention, For example, it can manufacture by preparing the solution or slurry containing a catalyst component, drying, baking, and shape | molding this solution or slurry.

  As starting materials for the catalyst components, oxides, sulfates, nitrates, carbonates, hydroxides, ammonium salts, halides, and the like of each element can be used. Examples of the molybdenum raw material include ammonium paramolybdate and molybdenum trioxide. Examples of the bismuth raw material that can be used include bismuth trioxide, bismuth nitrate, bismuth carbonate, and bismuth hydroxide. As the iron raw material, for example, ferric nitrate, ferric chloride and the like can be used. The raw material of the catalyst component may be only one kind for each element, or two or more kinds may be used in combination. Further, a raw material insoluble in water such as bismuth nitrate may be used by dissolving in an acid such as nitric acid in advance.

  As a method for preparing a solution or slurry containing a catalyst component, a known method such as a precipitation method or an oxide mixing method can be applied as long as the catalyst component is not significantly unevenly distributed. As the solvent of the solution or slurry, water, alcohol or the like can be used.

  As a method for drying a solution or slurry containing a catalyst component, various methods can be used, and examples thereof include an evaporating and drying method, a spray drying method, a drum drying method, and an airflow drying method. The model of the dryer used for drying, the temperature at the time of drying and the like are not particularly limited, and a dried catalyst precursor according to the purpose can be obtained by appropriately changing the drying conditions. Among these, as will be described later, it is preferable to use the spray drying method because the average particle diameter of the dried product can be easily controlled.

  The spray drying method can be performed using, for example, a spray dryer provided with a rotating disk type centrifugal atomizer, a two-fluid nozzle type atomizer, or the like. Conditions such as the inlet temperature and outlet temperature of the spray dryer are appropriately set so as to obtain a desired average particle size. For example, the general drying conditions in the case of spray drying an aqueous slurry containing 35 to 55% by mass of a solid using a spray dryer equipped with a rotating disk type centrifugal atomizer include an inlet temperature of 100 to 500 ° C., an outlet The temperature is 100 to 200 ° C., and the atomizer speed is 4000 to 25000 rpm.

  The powder after the solution or slurry containing the catalyst component is dried may contain a salt such as nitrate derived from the starting material of the catalyst component. If the salt remains, the mechanical strength of the catalyst molded body may be reduced. Therefore, after drying, the catalyst is fired to decompose the salt. Although known firing conditions can be applied as firing conditions for salt decomposition, it is preferably performed at 200 to 600 ° C. in an air atmosphere. The calcination time is appropriately selected according to the target catalyst molded body. A catalyst powder is obtained by the calcination.

  When the average particle size of the catalyst powder is reduced, many pores larger than 2 μm in pore size tend to be formed inside the catalyst. On the other hand, when the average particle diameter of the catalyst powder is increased, many pores smaller than 2 μm tend to be formed inside the catalyst. Further, when the average particle size of the catalyst powder is reduced, the contact point between the particles per unit volume increases, so that the mechanical strength of the obtained catalyst compact tends to be improved.

  Considering these, the average particle diameter of the catalyst powder is preferably 10 μm or more and 200 μm or less. When the average particle diameter is in the above range, the balance between selectivity and mechanical strength is excellent. The average particle diameter of the catalyst powder is more preferably 20 μm or more and 150 μm or less. The average particle diameter of the catalyst powder can be controlled within the above range by appropriately selecting the drying conditions, firing conditions, etc. of the solution or slurry containing the catalyst component. The average particle size of the catalyst powder is an average particle size measured using a particle size distribution measuring device “SALD-7000” (trade name, manufactured by Shimadzu Corporation).

  The bulk density of the catalyst powder is preferably in the range of 0.5 to 1.8 kg / L from the viewpoint of handleability during molding and the performance of the catalyst. Within this range, sufficient strength to withstand molding can be obtained, so that the particles are not easily crushed during molding, and the activity and selectivity of the catalyst are high. The bulk density of the catalyst powder is more preferably 0.8 to 1.2 kg / L. Here, the bulk specific gravity is a value measured by the method described in JIS K 6720-2: 1999. The bulk specific gravity of the catalyst powder can be adjusted, for example, by the concentration of the solution or slurry to be spray-dried, the mixing speed or the stirring speed when preparing the solution or slurry.

  The catalyst powder is then molded into a catalyst molded body. The method for forming the catalyst powder is not particularly limited, and can be performed by, for example, extrusion molding, tableting molding, rolling granulation, mold molding or the like.

  When manufacturing a catalyst molded body, you may add well-known additives, for example, organic compounds, such as polyvinyl alcohol, carboxymethylcellulose, and hydroxypropyl methylcellulose. Further, inorganic compounds such as graphite and diatomaceous earth, inorganic fibers such as glass fiber, ceramic fiber and carbon fiber may be added.

  The catalyst molded body obtained as described above may be fired again. Firing is usually performed in a temperature range of 200 to 600 ° C. for 1 to 3 hours. Thereby, a catalyst is manufactured.

The shape of the catalyst is not particularly limited, and may be any shape such as a spherical shape, a cylindrical shape (pellet shape), a ring shape, and an indefinite shape. In the case of a spherical shape, it does not have to be a true sphere and may be substantially spherical. The same applies to the cylindrical shape and the ring shape. About the magnitude | size of a catalyst, when the shape of a catalyst is spherical shape, 1-15 mm is preferable, as for an average diameter, 1-10 mm is more preferable, 3-10 mm is still more preferable, and 3-8 mm is especially preferable. The pore volume of the catalyst is preferably 0.2 to 0.7 cm ³ / g.

  In addition, the pore volume and pore diameter distribution of the catalyst in the present invention were measured by using a mercury intrusion porosimeter (trade name: “AutoPore IV 9500”, manufactured by micromeritics) at an average pressure increase rate of 0.01 to 0.3 MPa / second. The pore volume and the pore size distribution per unit mass of the catalyst measured for pressure in the range of 0.006 to 300 μm.

  The ratio of the pore volume in the pore diameter range of 0.1 to 2 μm to the pore volume in the pore diameter range of 0.1 to 100 μm of the catalyst that can be used in the present invention is not particularly limited, but preferably 0.30. It is the range of -0.98, More preferably, it is the range of 0.35-0.85. By setting the ratio of the pore volume in the range of 0.1 to 2 μm to the pore volume in the range of 0.1 to 100 μm to 0.30 or more, the diffusion efficiency in the pores is improved, and the target generation There is a tendency for the selectivity to goods to improve. On the other hand, when the ratio of the pore volume in the range of 0.1 to 2 μm to the pore volume in the range of 0.1 to 100 μm is 0.98 or less, the catalyst strength tends to be improved.

(Method for producing unsaturated aldehyde and unsaturated carboxylic acid)
In the method according to the present invention, using a fixed bed tubular reactor packed with a catalyst, at least one compound selected from the group consisting of propylene, isobutylene, tertiary butyl alcohol and methyl tertiary butyl ether is used as a raw material. The unsaturated aldehyde and unsaturated carboxylic acid corresponding to the raw material are produced by vapor phase catalytic oxidation with molecular oxygen or molecular oxygen-containing gas.

  In the present invention, by dividing the inside of the reaction tube in the fixed bed tubular reactor in the tube axis direction, a plurality of reaction zones are provided, and the catalyst is provided from the raw material inlet side to the outlet side of the reaction tube. The catalyst is packed in each reaction zone in the reaction tube so that the ratio of the pore volume in the range of 0.1 to 2 μm to the pore volume in the range of 0.1 to 100 μm is larger. By disposing a catalyst having a large pore volume ratio in the range of pore diameters of 0.1 to 2 μm on the outlet side, the temperature of the hot spot part is decreased in the production of the unsaturated aldehyde and unsaturated carboxylic acid, and Selectivity and yield of saturated aldehyde and unsaturated carboxylic acid can be improved.

  The composition of the catalyst charged in each reaction zone may be the same or different, but the catalyst activity is preferably the same. In addition, the shape of the catalyst filled in each reaction zone may be the same or different (for example, raw material inlet side: spherical catalyst, outlet side: pellet-like catalyst). It is preferable to fill the catalyst in the shape. Moreover, the packing density (bulk density) of the catalyst packed in each reaction zone may be the same or different. If there is a portion with an extremely high packing density, the reaction proceeds rapidly and a hot spot portion is likely to be generated. Therefore, the catalyst packing density is preferably in the range of 0.3 to 1.2 g / ml.

  The number of reaction zones in the reaction tube is not particularly limited, and the greater the number, the easier it is to control the temperature of the hot spot part of the catalyst layer. Can do. Further, the ratio of the length of the catalyst layer filled in each reaction zone is not particularly limited because the optimum value varies depending on the oxidation reaction conditions and the composition, shape, size, etc. of the catalyst filled in each reaction zone. Can be appropriately selected so as to obtain optimum activity, selectivity and yield. When filling the catalyst into the reaction tube, a catalyst diluted with an inert substance can be filled in each reaction zone.

  In the method according to the present invention, at least one compound selected from the group consisting of propylene, isobutylene, tertiary butyl alcohol and methyl tertiary butyl ether is used as a raw material, and it is solidified with molecular oxygen or a molecular oxygen-containing gas. Contact with catalyst. The concentration of the compound in the raw material and molecular oxygen or molecular oxygen-containing gas (hereinafter referred to as “source gas”) is usually 1 to 20% by volume. The molar ratio of the compound and molecular oxygen in the source gas is preferably 1: 0.5 to 1: 3. Water vapor may be added to the source gas, and the concentration of water vapor is usually 1 to 45% by volume. The reaction pressure is usually 0 to several hundred kPa, the reaction temperature is usually 250 to 400 ° C., and the contact time is usually 1.5 to 15 seconds.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. “Parts” in Examples and Comparative Examples are parts by mass. The raw material gas and the reaction gas were analyzed by gas chromatography. The composition of the catalyst component was determined from the charged amount of the catalyst raw material.

  The conversion rates of the reaction raw materials in Examples and Comparative Examples, the selectivity of the unsaturated aldehyde or unsaturated carboxylic acid to be produced, the total yield of unsaturated aldehyde and unsaturated carboxylic acid, and ΔT are respectively defined as follows: The

Conversion rate (%) = A / B × 100
Selectivity of unsaturated aldehyde (%) = C / A × 100
Selectivity of unsaturated carboxylic acid (%) = D / A × 100
Total yield (%) = (C + D) / B × 100
ΔT = (hot spot temperature (° C.)) − (Reaction temperature (° C.))
Here, A is the number of moles of the reacted raw material, B is the number of moles of the supplied raw material, C is the number of moles of the generated unsaturated aldehyde, and D is the number of moles of the generated unsaturated carboxylic acid. As for the temperature of the hot spot part, a thermocouple was installed inside the reaction tube, the actual reaction temperature was measured at intervals of 1 cm or 0.5 cm in the axial direction, and the reaction temperature was the temperature of the heat medium.

  The packing density was measured according to JIS K 7365: 1999.

  The pore volume and pore size distribution were measured using a mercury intrusion porosimeter (trade name: “AutoPore IV 9500”, manufactured by micromeritics), and the pressure was increased at an average pressure increase rate of 0.01 to 0.3 MPa / second. It carried out about the range of 0.006-300 micrometers. The average particle size of the catalyst powder was measured using a particle size distribution measuring device (trade name: “SALD-7000”, manufactured by Shimadzu Corporation).

<Catalyst Production Example 1: Preparation of catalyst (1)>
To 2000 parts of pure water, 500 parts of ammonium paramolybdate, 12.4 parts of ammonium paratungstate, 23.0 parts of cesium nitrate, 27.4 parts of antimony trioxide and 33.0 parts of bismuth trioxide are added and heated and stirred. did. Further, 209.8 parts of ferric nitrate, 75.5 parts of nickel nitrate, 453.3 parts of cobalt nitrate, 31.3 parts of lead nitrate and 5.6 parts of 85% by mass phosphoric acid were added successively, heated and stirred. An aqueous slurry was obtained. Thereafter, the aqueous slurry was spray-dried using a spray dryer equipped with a rotating disk type centrifugal atomizer. At this time, the rotation speed of the atomizer of the spray dryer was 22,000 rpm, the inlet temperature of the spray dryer was 250 ° C., and the outlet temperature was 170 ° C. Next, the dried particles were calcined at 300 ° C. for 1 hour and at 510 ° C. for 3 hours to obtain catalyst powder. The average particle size of the catalyst powder at this time was 30 μm.

  To 100 parts of the catalyst powder thus obtained, 5 parts of hydroxypropylmethylcellulose having a viscosity of 10,000 mPa · s at 20 ° C. when made into a 2% by mass aqueous solution was added and dry-mixed. 45 parts of pure water was mixed here and kneaded using a batch-type kneader having a double-armed stirring blade, and then in an extruder, a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm. The object was molded. Subsequently, the obtained molded product was dried at 110 ° C. using a hot air dryer and further calcined at 400 ° C. for 3 hours to obtain a catalyst (1).

The composition of elements other than oxygen in the obtained catalyst (1) was Mo ₁₂ W _0.2 Bi _0.6 Fe _2.2 Sb _0.8 Ni _1.1 Co _6.6 Pb _0.4 P _0.2 Cs _0.5 . The ratio of the pore volume in the range of 0.1 to 2 μm to the pore volume in the range of 0.1 to 100 μm of the catalyst (1) was 0.36. The pore volume in the range of pore diameters of 0.1 to 100 μm was 0.60 ml / g.

<Catalyst Production Example 2: Preparation of catalyst (2)>
In the preparation method of the catalyst (1) of the catalyst production example 1, the same procedure as in the catalyst production method 1 except that the atomizer rotation speed of the spray dryer was 12,000 rpm and the average particle diameter of the catalyst powder was 80 μm. Thus, catalyst (2) was obtained. The ratio of the pore volume in the range of the pore diameter of 0.1 to 2 μm to the pore volume in the range of the pore diameter of 0.1 to 100 μm of the catalyst (2) was 0.62. Moreover, the pore volume in the range of pore diameters of 0.1 to 100 μm was 0.53 ml / g.

<Catalyst Production Example 3: Preparation of Catalyst (3)>
In the preparation method of the catalyst (1) of the catalyst production example 1, the same procedure as in the catalyst production method 1 except that the atomizer rotation speed of the spray dryer was set to 7,000 rpm and the average particle diameter of the catalyst powder was set to 120 μm. Catalyst (3) was obtained. The ratio of the pore volume in the range of 0.1-2 μm pore diameter to the pore volume in the range of 0.1-100 μm pore diameter of catalyst (3) was 0.84. The pore volume in the range of pore diameters of 0.1 to 100 μm was 0.43 ml / g.

<Catalyst Production Example 4: Preparation of Catalyst (4)>
To 2000 parts of water, 500 parts of ammonium paramolybdate, 27.6 parts of cesium nitrate, 3.2 parts of tin oxide, 14.2 parts of silicon dioxide, 0.18 part of titanium dioxide and 17.2 parts of antimony trioxide are added and heated. Stirred (Liquid A). Separately from the liquid A, 75 parts of 60% by mass nitric acid was added to 1000 parts of water to make it uniform, and then 103.0 parts of bismuth nitrate were added and dissolved. To this, 238.4 parts of ferric nitrate, 137.2 parts of nickel nitrate, 343.3 parts of cobalt nitrate, 484.3 parts of magnesium nitrate and 2.05 parts of cerium nitrate were sequentially added and dissolved (Liquid B). B liquid was added to A liquid to make an aqueous slurry. Thereafter, the aqueous slurry was dried, calcined and molded under the preparation conditions of Catalyst Production Example 1 to obtain a catalyst (4). The average particle size of the catalyst powder at this time was 30 μm.

The composition of elements other than oxygen in the obtained catalyst (4) was Mo ₁₂ Bi _0.9 Fe _2.5 Ni ₂ Co ₅ Mg _0.8 Sn _0.1 Si ₁ Ce _0.02 Ti _0.01 Sb _0.5 Cs _0.6 . The ratio of the pore volume in the range of 0.1-2 μm pore diameter to the pore volume in the range of 0.1-100 μm pore diameter of catalyst (4) was 0.36. The pore volume in the range of pore diameters of 0.1 to 100 μm was 0.63 ml / g.

<Catalyst Production Example 5: Preparation of catalyst (5)>
In the preparation method of the catalyst (4) of the catalyst production example 4, the same procedure as in the catalyst production method 4 except that the atomizer rotation speed of the spray dryer was 12,000 rpm and the average particle size of the catalyst powder was 80 μm. A catalyst (5) was obtained. The ratio of the pore volume in the range of the pore diameter of 0.1 to 2 μm to the pore volume in the range of the pore diameter of 0.1 to 100 μm of the catalyst (5) was 0.58. The pore volume in the range of pore diameters of 0.1 to 100 μm was 0.60 ml / g.

<Catalyst Production Example 6: Preparation of catalyst (6)>
In the preparation method of the catalyst (4) of the catalyst production example 4, the atomization speed of the spray dryer was set to 7,000 rpm, and the average particle size of the catalyst powder was set to 120 μm. A catalyst (6) was obtained. The ratio of the pore volume in the range of the pore diameter of 0.1 to 2 μm to the pore volume in the range of the pore diameter of 0.1 to 100 μm of the catalyst (6) was 0.76. The pore volume in the range of pore diameters of 0.1 to 100 μm was 0.48 ml / g.

[Example 1]
In order from the raw material inlet side to the outlet side of a stainless steel reaction tube having an inner diameter of 25.4 mm, the catalyst (1) was packed in a layer length of 1500 mm and the catalyst (2) in a layer length of 1500 mm. While introducing a raw material mixed gas of 5% by volume of isobutylene, 12% by volume of oxygen, 10% by volume of water vapor and 73% by volume of nitrogen from the inlet of the reactor, a heat medium is circulated around the reaction tube to remove reaction heat. The reaction was carried out at a reaction temperature of 345 ° C. and a space velocity of 1400 hr ⁻¹ . The results are shown in Table 1.

[Example 2]
In Example 1, except that the catalyst (1) was packed in order from the reaction gas inlet side to the outlet side so that the layer length was 1000 mm, the catalyst (2) was a layer length of 1000 mm, and the catalyst (3) was a layer length of 1000 mm. Reacted in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, the reaction was performed in the same manner as in Example 1 except that only 3000 mm of catalyst (1) was filled. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, the reaction was performed in the same manner as in Example 1 except that only 3000 mm of the catalyst (2) was filled. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, the reaction was carried out in the same manner as in Example 1 except that only the catalyst (3) was packed 3000 mm. The results are shown in Table 1.

[Comparative Example 4]
In Example 1, the reaction was carried out in the same manner as in Example 1 except that the catalyst (2) was packed in a layer length of 1500 mm and the catalyst (1) in a layer length of 1500 mm in order from the raw material inlet side to the outlet side. It was. The results are shown in Table 1.

[Example 3]
In Example 1, the reaction was carried out in the same manner as in Example 1 except that the catalyst (5) was packed in a layer length of 1000 mm and the catalyst (6) in a layer length of 2000 mm in order from the raw material inlet side to the outlet side. It was. The results are shown in Table 1.

[Example 4]
In Example 1, except that the catalyst (4) was packed in order from the raw material inlet side to the outlet side so that the layer length was 500 mm, the catalyst (5) was a layer length of 1000 mm, and the catalyst (6) was a layer length of 1500 mm. The reaction was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
In Example 1, the reaction was performed in the same manner as in Example 1 except that only 3000 mm of catalyst (4) was filled. The results are shown in Table 1.

[Comparative Example 6]
In Example 1, the reaction was carried out in the same manner as in Example 1 except that the catalyst (6) was packed in a layer length of 1000 mm and the catalyst (4) in a layer length of 2000 mm in order from the raw material inlet side to the outlet side. It was. The results are shown in Table 1.

[Comparative Example 7]
In Example 1, the reaction was performed in the same manner as in Example 1 except that the catalyst (6) was packed in a layer length of 1500 mm and the catalyst (5) in a layer length of 1500 mm in order from the raw material inlet side to the outlet side. It was. The results are shown in Table 1.

Claims (1)

Using a fixed bed tubular reactor packed with a catalyst, starting from at least one compound selected from the group consisting of propylene, isobutylene, tertiary butyl alcohol and methyl tertiary butyl ether, molecular oxygen or molecular In the method of producing an unsaturated aldehyde and unsaturated carboxylic acid corresponding to a raw material by performing gas phase catalytic oxidation with an oxygen-containing gas,
The catalyst is a composite oxide containing at least molybdenum, bismuth and iron;
By dividing the inside of the reaction tube in the fixed bed tube reactor in the tube axis direction, a plurality of reaction zones are provided,
From the raw material inlet side to the outlet side of the reaction tube, the ratio of the pore volume in the pore diameter range of 0.1 to 2 μm to the pore volume in the pore diameter range of 0.1 to 100 μm of the catalyst increases. And a method for producing an unsaturated aldehyde and an unsaturated carboxylic acid, wherein each reaction zone in the reaction tube is filled with the catalyst.