JP3939187B2 - Process for producing unsaturated aldehyde - Google Patents

Description

【００４８】
【表２】

【００４９】
【表３】

【００５０】
【発明の効果】
本発明によれば、モリブデン系の触媒を充填した固定床多管式反応器を用いた気相接触酸化反応によって不飽和アルデヒドおよび／または不飽和カルボン酸を製造する場合に、ホットスポット部に位置する触媒の劣化を抑制し、ホットスポット部がどこに発生するかによらず、また、原料ガス濃度が高い場合であっても、高い収率を維持しながら長期にわたって反応を継続することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an unsaturated aldehyde and / or an unsaturated carboxylic acid. Specifically, using a fixed bed multitubular reactor packed with a catalyst, starting from at least one compound selected from propylene, isobutylene, t-butyl alcohol and methyl-t-butyl ether, molecular oxygen or molecular oxygen The present invention relates to a method for producing an unsaturated aldehyde and / or an unsaturated carboxylic acid by gas phase catalytic oxidation with a contained gas.
[0002]
[Prior art]
Using a fixed bed multi-tubular reactor packed with a catalyst, starting from at least one compound selected from propylene, isobutylene, t-butyl alcohol and methyl-t-butyl ether, and using molecular oxygen or molecular oxygen-containing gas With respect to a method for producing an unsaturated aldehyde and / or an unsaturated carboxylic acid corresponding to each by gas phase catalytic oxidation, there have been some proposals (for example, Japanese Patent Publication No. 53-30688, Japanese Patent Publication No. 63). No. -38331, JP-A-3-294238, JP-A-3-294239, JP-A-4-217932, JP-A-8-3093, JP-A-10-168003, etc.) Some methods are industrially practiced.
[0003]
Since this gas phase catalytic oxidation reaction is accompanied by a very exothermic reaction, local abnormally high temperature portions (hereinafter sometimes referred to as hot spot portions) are generated in the catalyst layer. In particular, as long as the oxidation reaction using a fixed bed multitubular reactor is performed, it is inevitable that hot spot portions are not generated in the catalyst layer.
If the temperature of the hot spot part is high, an excessive oxidation reaction is caused to reduce the yield, or in the worst case, a runaway reaction is caused. In addition, since the catalyst located in the hot spot is exposed to high temperatures, the physical and chemical properties of the catalyst change, which accelerates the deterioration of the catalyst, such as a decrease in activity and the selectivity of the target product. Is done. In particular, in the case of a molybdenum-based catalyst, the degree of deterioration of the catalyst is large because the molybdenum component is sublimated and the catalyst composition and physical properties are easily changed.
[0004]
The above problem becomes more prominent when a reaction at a high space velocity or a reaction at a high raw material gas concentration is performed for the purpose of improving the productivity of the target product.
Regarding the above problems, focusing on the entire catalyst layer packed in the reaction tube, the catalyst located in the hot spot part deteriorates faster than the catalyst in other parts, and the yield of the target product is increased by long-term use. Significantly decreases, and it may be difficult to perform stable production. As described above, in the case of a molybdenum-based catalyst, or when a reaction at a high space velocity or a reaction at a high source gas concentration is performed, the degree of deterioration of the catalyst is particularly large.
[0005]
[Problems to be solved by the invention]
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.
[0006]
Accordingly, an object of the present invention is to provide a hot spot portion when an unsaturated aldehyde and / or an unsaturated carboxylic acid is produced by a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor packed with a molybdenum-based catalyst. It is possible to continue the reaction over a long period of time while maintaining a high yield, regardless of where the hot spot occurs, and even when the raw material gas concentration is high. It is to provide a method that can.
[0007]
[Means for Solving the Problems]
  The present inventor has intensively studied to solve the above problems. As a result, focusing on the ratio R of the apparent density of the catalyst to the true density of the catalyst (the apparent density of the catalyst / the true density of the catalyst), a catalyst having a relatively high R may be exposed to a higher temperature than a low catalyst. It was found that the degree of deterioration was small. Then, the inventors have conceived that the above problem can be solved by preparing a catalyst having a different R and filling the catalyst so that a catalyst having a high R is positioned at or near the hot spot portion.
  That is, the method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid according to the present invention uses propylene, isobutylene, t-butyl alcohol, and methyl-t-, using a fixed bed multitubular reactor packed with a catalyst. In a method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid corresponding to a raw material by subjecting at least one compound selected from butyl ether to gas phase catalytic oxidation with molecular oxygen or a molecular oxygen-containing gas, As the catalyst, oxides and / or composite oxides containing molybdenum, bismuth and iron as essential components are used, and a plurality of them are obtained by dividing the inside of each reaction tube in the fixed bed multitubular reactor in the tube axis direction. Set up reaction zones,
(1) changing the weight loss rate of the catalyst precursor;
(2) changing the type and / or amount of pore-forming agent added to the catalyst;
The catalysts having different ratios of the apparent density of the catalyst to the true density of the catalyst R (the apparent density of the catalyst / the true density of the catalyst) are prepared by at least one method selected from:Are filled with the different catalysts.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As a catalyst having molybdenum, bismuth and iron as essential components used in the present invention, at least one compound selected from propylene, isobutylene, t-butyl alcohol and methyl-t-butyl ether is used as a raw material, and by a gas phase catalytic oxidation reaction. Any compound that can produce the corresponding unsaturated aldehyde and / or unsaturated carboxylic acid can be used, but a composite oxide catalyst represented by the following general formula (1) is preferably used.
MoaWbBicFedAeBfCgDhEiOx (1)
(Where Mo is molybdenum, W is tungsten, Bi is bismuth, Fe is iron, A is at least one element selected from cobalt and nickel, B is at least one element selected from sodium, potassium, rubidium, cesium and thallium. Element, C is at least one element selected from boron, phosphorus, chromium, manganese, zinc, arsenic, niobium, tin, antimony, tellurium, cerium and lead, D is at least one selected from silicon, aluminum, titanium and zirconium Element, E is at least one element selected from alkaline earth metals, and O is oxygen, a, b, c, d, e, f, g, h, i, and x are Mo, W, Bi, Represents the atomic ratio of Fe, A, B, C, D, E and O, and when a = 12, 0 ≦ b ≦ 5, 0.1 ≦ c ≦ 10, 0.1 ≦ d ≦ 20, 1 ≦ e ≦ 20, 0.001 ≦ f ≦ 5, 0 ≦ g ≦ 10, 0 ≦ h ≦ 30, 0 ≦ i ≦ 5, and x Is a numerical value determined by the oxidation state of each element.)
There are no particular restrictions on the starting materials for the above catalyst component elements, and ammonium salts, nitrates, carbonates, chlorides, sulfates, hydroxides, organic acid salts, oxidation of metal elements generally used in this type of catalyst Or a mixture of these may be used, but ammonium salts and nitrates are preferably used.
[0009]
The mixed aqueous solution or aqueous slurry of the catalyst raw material salt may be prepared by a method generally used for this type of catalyst. For example, the catalyst raw material may be used as an aqueous solution, and these may be mixed sequentially. There are no particular restrictions on the mixing conditions (mixing order, temperature, pressure, pH, etc.) of the catalyst raw material. The catalyst mixed salt aqueous solution or aqueous slurry thus obtained may be concentrated to dryness as necessary to obtain a cake-like solid. The catalyst raw material salt mixed aqueous solution, aqueous slurry, or cake-like solid is subjected to heat treatment to obtain a catalyst precursor P1.
The form of the heat treatment method and catalyst precursor for obtaining the catalyst precursor P1 is not particularly limited. For example, a powdered catalyst precursor may be obtained using a spray dryer, a drum dryer or the like, or box-type drying is performed. A block or flake catalyst precursor may be obtained by heating in an air stream using a machine, a tunnel dryer or the like.
[0010]
The heat treatment conditions are such that the catalyst precursor P1 preferably has a weight loss rate of 10% by mass to less than 40% by mass, more preferably 13% by mass to 37% by mass, and even more preferably 15% by mass to 35% by mass. Set. However, even if the weight loss rate is out of the above range, it can of course be used.
The weight loss rate of the catalyst precursor is calculated from the following formula when the catalyst precursor P1 is uniformly mixed and accurately weighed about 10 g and heated at 300 ° C. for 1 hour in an air atmosphere.
Weight loss rate (mass%) = (catalyst precursor mass−catalyst precursor mass after heating) / catalyst precursor mass × 100
The weight loss is nitrate radicals, ammonium radicals and the like remaining in the catalyst precursor P1 which decomposes, volatilizes and sublimes by heat treatment, and moisture. (The nitrate and ammonium salts contained in the catalyst precursor P1 are decomposed and removed from the catalyst precursor P1 by heating at a high temperature. That is, the higher the weight loss rate, the higher the proportion of nitrate, ammonium salt, etc. It means that it is contained in.)
The above heat treatment conditions should be appropriately selected depending on the type of the heating device (dryer) and the characteristics of the heating device, and cannot be specified unconditionally. For example, when using a box-type dryer, What is necessary is just to process for 3 to 24 hours at the temperature below ° C.
[0011]
As described above, the catalyst precursor P1 whose weight reduction rate is preferably adjusted is sent to a subsequent molding step through a pulverization step and a classification step for obtaining a powder having an appropriate particle size as necessary.
Subsequently, a binder is added to and mixed with the catalyst precursor P1 whose weight loss rate is preferably adjusted within the above range to obtain a catalyst precursor P2.
The kind of the binder to be added to and mixed with the catalyst precursor P1 is not particularly limited, and examples thereof include known binders that can be used for catalyst molding, and water is preferable.
[0012]
The amount of the binder to be added to and mixed with the catalyst precursor P1, preferably the amount of water to be added and mixed with respect to the catalyst precursor P1, is preferably 5 mass with respect to 100 parts by mass of the catalyst precursor P1. Part by mass to 30 parts by mass, more preferably 8 parts by mass to 27 parts by mass, and even more preferably 11 parts by mass to 24 parts by mass.
If the addition amount is more than 30 parts by mass, the moldability of the catalyst precursor P2 is deteriorated and it may be impossible to mold. When the addition amount is less than 5 parts by mass, the bonding between the catalyst precursors P2 is weak, and even if the molding itself cannot be performed or can be molded, the mechanical strength of the catalyst may be lowered. In the case of extrusion molding, in the worst case, the molding machine is broken.
[0013]
The water added to the catalyst precursor P1 can be added in the form of an aqueous solution of various substances or a mixture of various substances and water.
Examples of the substance added together with water include a molding aid for improving moldability, a reinforcing agent and a binder for improving the strength of the catalyst, and a substance generally used as a pore forming agent for forming pores in the catalyst. As these substances, those which do not adversely affect the catalyst performance (activity, selectivity of target product) by addition are preferable. That is, (i) a mixture of an aqueous solution or water of a substance that does not remain in the catalyst after calcination, and (ii) an aqueous solution or water composed of a substance that does not adversely affect the catalyst performance even if it remains in the catalyst after calcination. It is a mixture.
[0014]
Specific examples of the above (i) include organic compounds such as ethylene glycol, glycerin, propionic acid, maleic acid, benzyl alcohol, propyl alcohol, butyl alcohol or phenol, nitric acid, ammonium nitrate, and ammonium carbonate.
Specific examples of the above (ii) include silica, alumina, glass fiber, silicon carbide, silicon nitride and the like that are generally known as reinforcing agents. According to the present invention, the produced catalyst has a practically sufficient mechanical strength, but when a higher mechanical strength is required, these reinforcing agents are added.
[0015]
These substances are preferably added in such an amount that the mechanical strength of the catalyst is not lowered to the extent that it cannot be practically used as an industrial catalyst since the mechanical strength of the catalyst is remarkably lowered when the addition amount is excessive.
When added in the form of an aqueous solution of various substances described above or a mixture of various substances and water, for example, when 20 parts by mass of a 5 mass% ethylene glycol aqueous solution is added to 100 parts by mass of the catalyst precursor P1 and molded. The amount of water added to P1 is 20 × (1-0.05) = 19 parts by mass.
The catalyst used in the present invention is a molded catalyst obtained by molding the catalyst precursor P2 into a fixed shape, or a supported catalyst in which the catalyst precursor P2 is supported on an arbitrary inert carrier having a fixed shape. Alternatively, a combination of these molded catalyst and supported catalyst may be used, but a molded catalyst obtained by molding the catalyst precursor P2 into a fixed shape is preferable.
[0016]
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. Of course, 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 columnar shape and the ring shape. In addition, the shape of the catalyst filled in each reaction zone may be the same or different (for example, gas inlet side: spherical catalyst, gas outlet side: pellet catalyst), but usually the same shaped molded catalyst or the same It is preferable to fill the shaped supported catalyst.
Regarding the size of the catalyst, when the shape of the catalyst is spherical, the average catalyst particle size is preferably 1 to 15 mm, more preferably 1 to 10 mm, still more preferably 3 to 10 mm, and even more preferably 3 to 8 mm. Are preferably used.
[0017]
The pore volume of the catalyst is preferably 0.2 to 0.6 cm^Three/ G, more preferably 0.25 to 0.55 cm^Three/ G.
In the case of a supported catalyst, the material of the support itself is not particularly limited, and any support that can be used normally when producing a catalyst for producing acrylic acid by vapor phase oxidation of acrolein can be used. Specific examples of usable carriers include alumina, silica, silica / alumina, titania, magnesia, steatite, silica magnesia, silica magnesia alumina, silicon carbide, silicon nitride, zeolite and the like.
[0018]
In the case of a supported catalyst, the loading ratio of the catalyst filled in each reaction zone is appropriately determined so as to obtain optimum activity and selectivity in consideration of oxidation reaction conditions, catalyst activity, strength, etc. Is 5 to 200%, more preferably 10 to 100%, and particularly preferably 15 to 50%.
In the present invention, the catalyst loading is calculated by the following equation.
Loading rate (%)
= [(Catalyst mass after calcination−Carrier mass) / Catalyst mass after calcination] × 100
There are no particular restrictions on the heat treatment conditions (so-called calcination conditions) at the time of catalyst preparation, and the calcination conditions generally employed in the production of this type of catalyst can be applied. The heat treatment temperature of the catalyst filled in each reaction zone may be the same or different. The heat treatment temperature is preferably 350 to 600 ° C., more preferably 400 to 550 ° C., and the heat treatment time is preferably 1 to 10 hours. is there.
[0019]
The molding method of the catalyst may be a conventionally known method. For example, a molding method such as an extrusion molding method, a tableting molding method, a granulation method (rolling granulation device, centrifugal fluid coating device), or a Malmerizer method can be applied. Of these, the extrusion molding method is preferable.
In the method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid according to the present invention, a plurality of reaction zones are provided by dividing the inside of each reaction tube in a fixed bed multitubular reactor in the tube axis direction. Each of the reaction zones is filled with the catalyst having a different ratio R (apparent density of catalyst / true density of catalyst) of the apparent density of the catalyst to the true density of the catalyst.
[0020]
In the present invention, the apparent density of the catalyst = 1 / (1 / true density + pore volume).
In the case of a so-called supported catalyst in which a catalytically active substance is supported on a carrier, only the catalytically active substance is peeled off from the surface of the carrier by any method, and the true density and pore volume of only the catalytically active substance are measured. R is calculated from the above equation.
Thus, by filling the catalyst with different ratios R of the apparent density of the catalyst to the true density, the unsaturated aldehyde and / or by the gas phase catalytic oxidation reaction using the fixed bed multitubular reactor filled with the molybdenum-based catalyst. Or, when producing unsaturated carboxylic acids, the reaction should be continued over a long period of time while maintaining a high yield, regardless of where the hot spot occurs and even when the raw material gas concentration is high. Can do it.
[0021]
A method for producing a catalyst having a ratio R of the apparent density of the catalyst with respect to the true density is not particularly limited. For example, the catalyst can be produced by the following methods (1) to (4) or a combination thereof.
(1) R can be changed by changing the weight loss rate of the catalyst precursor. If the weight loss rate is low, the formation of pores in the catalyst is reduced, so that the apparent density of the catalyst is increased. Since the true density does not change even if the production method is changed unless the composition of the catalyst changes extremely, R becomes large when the weight reduction rate is low. On the other hand, when the weight loss rate is high, the apparent density of the catalyst is low, so R is small.
[0022]
(2) Controlling the type and / or amount of pore-forming agent added to the catalyst. When a pore-forming agent having an action of forming pores is added to the catalyst and the amount added is relatively reduced, the apparent density increases and R increases. On the contrary, when the addition amount is relatively large, R becomes small. R can also be controlled by changing the type of pore forming agent.
(3) Although the effect of changing R is small, changing the catalyst composition (the type and addition ratio of the metal used as the catalyst raw material) changes the true density, so R also changes.
(4) R can also be controlled by changing the pressure during molding. For example, in the case of tableting, R increases as the pressure is increased, and R decreases as the pressure is decreased. Further, in the case of extrusion molding, if the extrusion pressure is increased, R increases, and if the extrusion pressure is decreased, R decreases.
[0023]
The range of the ratio R of the apparent density to the true density of the catalyst that can be used in the present invention (the apparent density of the catalyst / the true density of the catalyst) is not particularly limited, but is preferably 0.25 to 0.55, more preferably 0.30 to 0.50.
If the ratio of the apparent density to the true density of the catalyst is less than 0.25, the efficiency of diffusion in the pores may increase as the pore volume increases. In this case, the activity of the catalyst and the selection of the desired product Although the rate is improved, it is not preferable because the catalyst strength is significantly reduced.
When the ratio of the apparent density to the true density of the catalyst is larger than 0.55, the above is reversed and the catalyst strength is improved, but the activity of the catalyst and the selectivity to the target product are remarkably lowered, which is not preferable.
[0024]
In the present invention, a plurality of reaction zones are provided by dividing the inside of each reaction tube in the fixed bed multitubular reactor in the tube axis direction, and R prepared by the above-described method is provided in the plurality of reaction zones. Are filled with a plurality of different catalysts.
The filling arrangement method is not particularly limited. For example, the filling arrangement is such that R becomes smaller from the gas inlet side to the gas outlet side, or R is once from the gas inlet side to the gas outlet side. Although the arrangement | positioning etc. which are filled so that it may become small after becoming large etc. are mentioned, Preferably, the catalyst from which R differs is arrange | positioned so that R may become smaller toward the gas outlet side from the gas inlet side of each reaction tube. That is, the catalyst having the largest R is arranged on the inlet side, and the catalyst having the smallest R is arranged on the outlet side. Further, in the arrangement in which R is once increased from the gas inlet side toward the gas outlet side and then packed so as to decrease, the packed bed length of the catalyst having a large R at the gas inlet portion is 60% or less of the total catalyst layer. Is preferable, 5 to 50% is more preferable, and 10 to 40% is more preferable.
[0025]
In this way, by arranging a plurality of catalysts having different apparent density ratios R (catalyst apparent density / catalyst true density) to the true density of the catalyst, a fixed bed multitubular reactor filled with a molybdenum-based catalyst. When an unsaturated aldehyde and / or unsaturated carboxylic acid is produced by a gas phase catalytic oxidation reaction using a catalyst, deterioration of the catalyst located in the hot spot part is suppressed, regardless of where the hot spot part occurs, Even when the raw material gas concentration is high, the reaction can be continued for a long period of time while maintaining a high yield. In addition, when the catalyst activity is controlled only by using catalysts having different activities as in the prior art, there is a limit especially when the raw material gas concentration is high. However, if the method according to the present invention is used, the raw material gas concentration is reduced. Even if it is high, the reaction can be continued over a long period of time while maintaining a high yield regardless of where the hot spot portion is generated.
[0026]
In the method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid according to the present invention, it is further preferable that the activities of the catalysts charged in the plurality of reaction zones are different.
The manufacturing method of the said catalyst from which the said activity differs is not specifically limited, For example, a conventionally well-known method can be used. Specifically, for example, a method of changing the kind and / or amount of at least one element selected from sodium, potassium, rubidium, cesium and thallium (component B as used in the catalyst used in the present invention), a method of changing the loading rate, Examples thereof include a method for changing the calcination temperature, a method for changing the dilution rate, a method for combining the supported catalyst and the molded catalyst, a method for changing the particle size of the catalyst, and a method using a combination thereof.
[0027]
When the plurality of reaction zones are filled with the catalysts having different activities as described above, that is, the ratio R of the apparent density of the catalyst to the true density of the catalyst (the apparent density of the catalyst / the true density of the catalyst) is different, and In the case where the plurality of reaction zones are filled with catalysts having different activities, the method for filling the catalyst is not particularly limited. When focusing on R, for example, as described above, the gas is introduced from the gas inlet side. An arrangement in which R is reduced toward the outlet side and an arrangement in which R is once increased from the gas inlet side to the gas outlet side, and an arrangement in which the R is reduced after the increase is mentioned. In this case, for example, the filling is performed so that the activity is sequentially increased from the gas inlet side to the gas outlet side, or the activity is once decreased from the gas inlet side to the gas outlet side. Arrangement and the like to be filled so that, preferably, arranging the activities of different catalysts such activity is sequentially increased toward the gas outlet side from the gas inlet side of each reaction tube. That is, the catalyst having the lowest activity is arranged on the inlet side, and the catalyst having the highest activity is arranged on the outlet side. Further, in the arrangement in which the activity is once lowered from the gas inlet side toward the gas outlet side and then packed so as to increase, the packed bed length of the highly active catalyst at the gas inlet portion is preferably 60% or less of the total catalyst layer. 5 to 50% is more preferable, and 10 to 40% is more preferable.
[0028]
By arranging a plurality of catalysts having different activities in this way, unsaturated aldehydes and / or unsaturated carboxylic acids can be formed by a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor filled with a molybdenum-based catalyst. In the production, the deterioration of the catalyst located in the hot spot part is further suppressed, and the high yield is maintained regardless of where the hot spot part occurs and even when the raw material gas concentration is high. However, the reaction can be continued for a long time.
As a most preferable form of the catalyst filling arrangement, R is filled so that R becomes smaller from the gas inlet side to the gas outlet side, and the activity is directed from the gas inlet side to the gas outlet side. In this form, the filling is performed so that the activity is sequentially increased.
[0029]
The number of reaction zones is not particularly limited, and the greater the number, the easier it is to control the hot spot temperature of the catalyst layer. However, industrially, the target effect can be sufficiently obtained by setting it to about 2 or 3. In addition, the optimal value for the split ratio of the catalyst layer cannot be specified because it depends on the oxidation reaction conditions and the composition, shape, size, etc. of the catalyst packed in each layer. May be appropriately selected so as to obtain
When filling the catalyst into each reaction tube, the catalyst diluted with an inert substance can be filled into each reaction zone.
[0030]
Unsaturation corresponding to the raw material by subjecting at least one compound selected from propylene, isobutylene, t-butyl alcohol, and methyl-t-butyl ether as a raw material to gas phase catalytic oxidation with molecular oxygen or a molecular oxygen-containing gas The method for producing the aldehyde and / or the unsaturated carboxylic acid is not particularly limited except that the catalyst of the present invention is used as a catalyst, and can be carried out under generally used apparatuses, methods and conditions. .
That is, the gas phase catalytic reaction in the present invention may be carried out by a normal single flow method or a recycling method, and a fixed bed reactor, a fluidized bed reactor, a moving bed reactor or the like can be used as the reactor.
[0031]
Examples of the reaction conditions include 1 to 15% by volume of at least one compound selected from propylene, isobutylene, t-butyl alcohol and methyl-t-butyl ether as a source gas, and a volume ratio of 1 to 1 with respect to the source gas. A mixed gas composed of molecular oxygen in a range of 10 times and an inert gas as a diluent, for example, water vapor, nitrogen, carbon dioxide, etc., in a temperature range of 250 to 450 ° C. under a pressure of 0.1 to 1 MPa and 300 to 5000 hr^-1What is necessary is just to make it contact with the catalyst of this invention and to make it react with the space velocity of (STP).
According to the method of the present invention, particularly remarkable results are obtained as compared with the conventional method under high-load reaction conditions aimed at increasing productivity, for example, under higher raw material gas concentrations or higher space velocity conditions. can get. In particular, the object of the present invention can be achieved even when a high-concentration source gas having a source gas concentration of 7% by volume or more, more strictly 9% by volume or more is used.
[0032]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not restrict | limited at all by these Examples. The conversion rate, selectivity, and yield in this specification are defined as follows.
Conversion (mol%) = (mol number of reacted starting material) / (mol number of supplied starting material) × 100
Selectivity (mol%) = (number of moles of unsaturated aldehyde and unsaturated carboxylic acid produced) / (number of moles of reacted starting material)
Yield (mol%) = (number of moles of unsaturated aldehyde and unsaturated carboxylic acid produced) / (number of moles of starting material fed) × 100
Further, the true density and pore volume of the catalyst were measured by the following measuring instruments and methods.
[0033]
True density:
Measuring instrument: AutoPycnometer 1320 manufactured by Micromeritics
Measuring method: About 4 g of the catalyst was weighed out, placed in a measuring cell, and set in the measuring instrument.
Pore volume:
Measuring device: AutoPoreIII (mercury press-fitting method) manufactured by Micromeritics
Measurement method: About 2 g of the catalyst was weighed and measured in a pressure measurement range of 0 to 414 MPa and an equivalent time of 10 seconds.
[0034]
(Catalyst production example 1: Preparation of catalyst (1))
While heating and stirring 10 L of pure water, 1500 g of ammonium molybdate was dissolved, and 425 g of 20% by mass silica sol was further added. A solution prepared by dissolving 1236 g of cobalt nitrate, 412 g of nickel nitrate, 372 g of iron nitrate, and 5.7 g of potassium nitrate in 1000 ml of pure water was added dropwise to this mixed solution with vigorous stirring. Subsequently, a solution obtained by dissolving 446 g of bismuth nitrate in an aqueous solution obtained by adding 250 ml of concentrated nitric acid to 500 ml of pure water was added dropwise with vigorous stirring. The resulting suspension was heated and stirred, and most of the water was evaporated to obtain a cake-like solid. The obtained cake-like solid was heat-treated with a box-type dryer (heated gas temperature: 170 ° C., heated gas linear velocity: 1.2 m / sec, heat treatment time: 12 hours), and the block-shaped catalyst precursor was Obtained. After pulverizing this catalyst precursor, the weight loss rate was measured and found to be 18.9% by mass. Next, a 50% by mass ammonium nitrate aqueous solution was added at a rate of 260 g to 1 kg of the catalyst precursor powder, kneaded for 1 hour, and then extruded into a ring shape having an outer diameter of 6.0 mm, an inner diameter of 2.0 mm, and a height of 6.0 mm. Molded. Next, the molded body was calcined at 480 ° C. for 5 hours under air flow to obtain a catalyst (1). The metal element composition excluding oxygen of this catalyst was as follows.
[0035]
Catalyst (1): Mo₁₂Co₆Ni₂Bi_1.3Fe_1.3Si₂K_0.08
The ratio R of the apparent density to the true density of the catalyst (1) (the apparent density of the catalyst / the true density of the catalyst) was 0.35.
Catalyst composition of catalyst (1), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
(Catalyst Production Examples 2-3: Preparation of Catalysts (2)-(3))
In the preparation method of the catalyst (1) of the catalyst production example 1, the catalysts (2) to (2) are prepared in the same manner as in the catalyst production example 1 except that the amount of the 50 mass% ammonium nitrate aqueous solution added to the catalyst precursor P1 is changed. (3) was obtained respectively.
[0036]
Catalyst composition of catalysts (2) to (3), weight loss rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (catalyst The apparent density of the catalyst / the true density of the catalyst is summarized in Table 1.
(Catalyst production example 4: Preparation of catalyst (4))
In the preparation method of the catalyst (1) of the catalyst production example 1 above, the catalyst ( 4) was obtained.
Catalyst composition of catalyst (4), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
[0037]
(Catalyst Production Example 5: Preparation of catalyst (5))
A catalyst (5) was obtained in the same manner as in Catalyst Production Example 1, except that the amount of potassium nitrate added was changed to 7.2 g in the method for preparing the catalyst (1) of Catalyst Production Example 1. The metal element composition excluding oxygen of this catalyst was as follows.
Catalyst (5): Mo₁₂Co₆Ni₂Bi_1.3Fe_1.3Si₂K_0.1
Catalyst composition of catalyst (5), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
[0038]
(Catalyst Production Example 6: Preparation of catalyst (6))
In the preparation method of the catalyst (1) of the catalyst production example 1 above, among the heat treatment conditions for the cake-like solid, the heating gas temperature is changed to 220 ° C., and the amount of the ammonium nitrate aqueous solution of 50% by mass added to the catalyst precursor P1 A catalyst (6) was obtained in the same manner as in Catalyst Production Example 1 except that
Catalyst composition of catalyst (6), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
[0039]
(Catalyst Production Example 7: Preparation of catalyst (7))
In the preparation method of the catalyst (1) of the catalyst production example 1, the amount of potassium nitrate added was changed to 3.6 g, and the amount of 50 mass% ammonium nitrate aqueous solution added to the catalyst precursor P1 and the size of the catalyst were changed. Except for this, a catalyst (7) was obtained in the same manner as in Catalyst Production Example 1. The metal element composition excluding oxygen of this catalyst was as follows.
Catalyst (7): Mo₁₂Co₆Ni₂Bi_1.3Fe_1.3Si₂K_0.05
Catalyst composition of catalyst (7), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
[0040]
(Catalyst Production Example 8: Preparation of catalyst (8))
A catalyst (8) was obtained in the same manner as in Catalyst Preparation Example 7, except that the amount of 50 mass% ammonium nitrate aqueous solution added to the catalyst precursor P1 was changed in the preparation method of the catalyst (7) of the catalyst preparation example 7. .
Catalyst composition of catalyst (8), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
(Catalyst Production Example 9: Preparation of catalyst (9))
In the preparation method of catalyst (1) of catalyst production example 1 above, 9.7 g of cesium nitrate was used instead of potassium nitrate, and the amount of 50 mass% ammonium nitrate aqueous solution added to catalyst precursor P1 and the size of the catalyst were changed. Except for the above, a catalyst (9) was obtained in the same manner as in Catalyst Production Example 1. The metal element composition excluding oxygen of this catalyst was as follows.
[0041]
Catalyst (9): Mo₁₂Co₆Ni₂Bi_1.3Fe_1.3Si₂Cs_0.07
Catalyst composition of catalyst (9), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
(Catalyst Production Example 10: Preparation of catalyst (10))
A catalyst (10) was obtained in the same manner as in Catalyst Preparation Example 9 except that the amount of the 50 mass% ammonium nitrate aqueous solution added to the catalyst precursor P1 was changed in the preparation method of the catalyst (9) of Catalyst Preparation Example 9. .
[0042]
Catalyst composition of catalyst (10), reduction rate of catalyst precursor P1, amount of binder added to 100 parts by mass of catalyst precursor P1, catalyst size, and ratio of apparent density to true density R (apparent density of catalyst / The true density of the catalyst) is summarized in Table 1.
(Reference Examples 1 to 10)
Into a stainless steel reaction tube having an inner diameter of 25 mm heated with molten nitrate, the catalysts (1) to (10) obtained in Catalyst Production Examples 1 to 10 are filled so as to have a layer length of 200 mm, respectively. Space velocity 1500h^-1(STP) was introduced to carry out the vapor phase catalytic oxidation reaction of propylene. The results are shown in Table 2.
[0043]
Propylene 3% by volume
Air 30% by volume
Water vapor 40%
Nitrogen 27% by volume
Example 1
A stainless steel reaction tube having an inner diameter of 25 mm heated with molten nitrate is packed in order from the reaction gas inlet side to the outlet side so that the layer length is 1500 mm and the catalyst (2) is 1500 mm. , A reaction gas having the following composition with a space velocity of 1500 h^-1(STP) was introduced to carry out the vapor phase catalytic oxidation reaction of propylene. The results are shown in Table 3.
[0044]
Propylene 5.5% by volume
Air 50.0% by volume
Water vapor 10.0% by volume
Nitrogen 34.5% by volume
(Comparative Examples 1-2)
In Example 1, a gas phase contact reaction was performed in the same manner as in Example 1 except that only the catalyst (1) was packed with a layer length of 3000 mm, or only the catalyst (2) was packed with a layer length of 3000 mm. The results are shown in Table 3.
[0045]
(Example 2, Comparative Examples 3-4)
In Example 1, a gas phase catalytic oxidation reaction was performed in the same manner as in Example 1 except that the catalyst was charged as shown in Table 3 and the reaction gas composition was changed as follows. The results are shown in Table 3.
Propylene 6.5% by volume
Air 57.0% by volume
Water vapor 10.0% by volume
Nitrogen 26.5% by volume
(Examples 3 to 5, Comparative Example 5)
In Example 1, a gas phase catalytic oxidation reaction was performed in the same manner as in Example 1 except that the catalyst was charged as shown in Table 3 and the reaction gas composition was changed as follows. The results are shown in Table 3.
[0046]
Propylene 8.0% by volume
Air 70.0% by volume
Water vapor 10.0% by volume
Nitrogen 12.0% by volume
[0047]
[Table 1]

[0048]
[Table 2]

[0049]
[Table 3]

[0050]
【The invention's effect】
According to the present invention, when an unsaturated aldehyde and / or an unsaturated carboxylic acid is produced by a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor filled with a molybdenum-based catalyst, The catalyst can be prevented from deteriorating, and the reaction can be continued for a long period of time while maintaining a high yield regardless of where the hot spot portion is generated and even when the raw material gas concentration is high.

Claims (5)

Using a fixed bed multitubular reactor packed with a catalyst, using as raw material at least one compound selected from propylene, isobutylene, t-butyl alcohol, and methyl-t-butyl ether, molecular oxygen or molecular oxygen-containing gas In the method of producing an unsaturated aldehyde and / or unsaturated carboxylic acid corresponding to a raw material by performing gas phase catalytic oxidation by
As the catalyst, an oxide and / or a composite oxide containing molybdenum, bismuth and iron as essential components is used,
A plurality of reaction zones are provided by dividing the inside of each reaction tube in the fixed bed multitubular reactor in the tube axis direction,
(1) changing the weight loss rate of the catalyst precursor;
(2) changing the type and / or amount of pore-forming agent added to the catalyst;
The catalyst having different ratio R (apparent density of catalyst / true density of catalyst) of the apparent density of the catalyst to the true density of the catalyst is prepared by at least one method selected from the above, and the catalyst having the different R in each reaction zone Each filling ,
A method for producing an unsaturated aldehyde and / or an unsaturated carboxylic acid.   2. The unsaturated aldehyde and / or the aldehyde according to claim 1, wherein the plurality of reaction zones are filled with the catalyst having different R so that R becomes smaller from the gas inlet side to the gas outlet side of each reaction tube. A method for producing an unsaturated carboxylic acid.   The method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid according to claim 1 or 2, wherein the activity of the catalyst charged in each of the plurality of reaction zones is different.   The unsaturated aldehyde and / or the aldehyde according to claim 3, wherein the plurality of reaction zones are filled with the catalyst having different activities so that the activity becomes higher from the gas inlet side to the gas outlet side of each reaction tube. A method for producing an unsaturated carboxylic acid.   The method for producing an unsaturated aldehyde and / or unsaturated carboxylic acid according to any one of claims 1 to 4, wherein the number of reaction zones is 2 or 3.