RU2621715C2 - Method of obtaining an unsaturated aldehyde and/or unsaturated carboxylic acid - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of receipt of acrolein and acrylic acid or methacrolein and methacrylic acid, which effect on propylene or, at least, on one type of compounds selected from the group consisting of isobutylene tertiary butanol, as has a contact oxidation using gas containing molecular oxygen, using a fixed bed multitube reactor, where (A) provide many layers of catalyst formed by division of catalyst layer in layer N (N is an integer equal to or greater than 2) in the direction of flow of gaseous source materials in reaction tubes. And among segments of the catalyst layer of catalyst, which is located on the near side of the input reactive gas is defined as Zin, while catalyst layer located at the farthest outlet side reactive gas is defined as Zout, and (B) catalyst downloaded so that load into catalyst activity Zout, higher than loaded catalyst activity in Zin, and thus that is satisfied by the following equation (1): 0.5≤ (Cmax-Ccrs) (1), where Cmax is the degree of transformation of source materials in which the desired output product becomes maximum; Ccrs and represents the degree of transformation of raw materials where high/low ratio between the Tin and Tout changes to reverse when the maximum temperature layer of the catalyst Zin is defined as Tin, and the maximum temperature of the catalyst bed Zout is defined as Tout, and the conversion of the starting materials varies.

EFFECT: method enables stable work process over an extended period of time.

9 cl, 7 ex

Description

FIELD OF THE INVENTION

The present invention relates to a method for producing acrolein and acrylic acid by exposing propylene to gas-phase contact oxidation using molecular oxygen or using a gas containing molecular oxygen, or to a method for producing methacrolein and methacrylic acid by contacting isobutylene and / or tertiary butanol with gas-phase contact oxidation using molecular oxygen or using a gas containing molecular oxygen.

State of the art

A method for producing an unsaturated aldehyde or unsaturated carboxylic acid using appropriate propylene, isobutylene or tertiary butanol as starting materials is widely carried out on an industrial scale. However, generating a local high-temperature portion (a local overheating portion) in the catalyst bed is a serious problem. The generation of a local superheat section leads to a reduction in the catalyst lifetime or yield due to an excessive oxidation reaction, and in the worst case, to an uncontrolled reaction. For this reason, some technologies have been proposed to suppress the local overheating area. For example, Patent Document 1 describes a technology for reducing the temperature of a local superheat section using a catalyst whose activity is controlled by changing its amount on a carrier, or using a catalyst whose activity is controlled by changing the temperature of the calcining of the catalyst. Patent Document 2 describes a catalyst use technology whose activity is controlled by changing the ratio of the apparent density of the catalyst. Patent document 3 describes a catalyst use technology, the activity of which is controlled not only by changing the content of the inert component of the molded catalyst mass, but also by changing the occupied volume of the molded catalyst mass, type and / or amount of alkali metal, or catalyst calcination temperature. Patent Document 4 describes a technology for providing reaction zones having a different occupied volume of a molded catalyst mass and mixing an inert substance in at least one of the reaction zones. Patent document 5 describes a technology for using a catalyst, the activity of which is controlled by changing the temperature of calcination of the catalyst. Patent document 6 describes a catalyst use technology, the activity of which is controlled by changing the occupied volume of the catalyst, the calcination temperature and / or the type or amount of alkali metal.

Prior Art Documents

Patent document

[Patent Document 1] Japanese Patent No. 3775872

[Patent Document 2] JP-A-2004-2209

[Patent Document 3] JP-A-2001-328951

[Patent Document 4] JP-A-2005-320315

[Patent Document 5] JP-A-8-3093

[Patent Document 6] JP-A-2001-226302

SUMMARY OF THE INVENTION

The problem that the invention must solve

Even under the assumption of suppressing the local overheating region by the above-mentioned means, the suppression is still insufficient. In addition, there is such a problem that the performance and lifetime of the catalyst expected in an industrial plant are not always obtained and, therefore, an improvement is desirable, for example, as discussed below.

(1) A method of using a catalyst, the activity of which is controlled by changing the occupied volume of the catalyst, is useful as a method of suppressing a local overheating section. However, in an industrial installation, in the case where several tens of thousands of reaction tubes are present and the inner diameter of each reaction tube is from 20 mm to 30 mm, an error of approximately ± 0.2 mm is possible. Insofar as catalysts having a small occupied volume are considered, such an effect may be negligible. However, it is noted that in catalysts having a large occupied volume, namely, in catalysts having a large particle diameter of the catalyst, there may be a case where the aforementioned effect is not negligible. Specifically, the problems are illustrated that, in the case of loading, a bridge is formed inside the reaction tube, so a huge amount of work is needed to fix this; that there is easily a variation in the pressure drops in each reaction tube due to a change in the charged amount or loading density, while causing an inhomogeneous distribution of the flow rate of the gaseous feed materials; and that a lot of work is also needed to fix this. One can easily imagine that in the case when the shape of the catalyst is non-spherical, this problem is exacerbated.

(2) In addition, in an industrial installation, there may be a case when not only there is a variation in the diameters of the reaction tubes, as described above, but there may also be a variation in the ability to remove heat due to the structure of the reactor, which generates the most uneven distribution of the temperature of the heated medium in the horizontal direction or in the vertical direction or the uneven distribution of the gas flow rate in each reaction tube. Thus, there is essentially the impossibility of using the catalysts in the same state in all reaction tubes. The authors of the present invention analyzed the catalysts used in an industrial installation. As a result, they saw a reaction tube in which the catalysts in the inlet for the gaseous feed materials are locally damaged; a reaction tube in which the catalysts are gradually damaged throughout the tube; and in addition, unexpectedly, a reaction tube in which the catalysts in the outlet part for gaseous starting materials are damaged, compared with the catalysts in the inlet part. This suggests the possibility that the temperature of the local overheating of the catalyst layer on the output side for gaseous feed materials is extremely high. In the worst case, there is a risk of an uncontrolled reaction. It is assumed that this is caused by the problem that due to the variation in the diameter of the reaction tubes, the variation in the ability to remove heat resulting from the structure of the reactor, the uneven distribution of the temperature of the heated medium in the horizontal direction or in the vertical direction, or due to the uneven distribution of gas flow rates in each reaction tube in an industrial plant, as described above, varies the degree of conversion of the hydrocarbon feedstock and the shape of the uneven distribution eniya temperature. Thus, the development of technology to maintain high yield in a safe and stable manner over a long period of time, even in an industrial installation, is considered as a problem.

Means of solving the problem

The inventors of the present invention have discovered the fact that it is preferable to operate an industrial plant in such a conversion of the starting materials that the catalyst provides maximum yield; in a large number of reaction tubes, the catalyst is selected so that the upper temperature limit for the use of the catalyst, which should be used in the conversion of the starting materials, is not exceeded; however, in an industrial plant there is a deviation from the reaction conditions described above, and for this reason, in the reactors, in general, reaction tubes are present where the degree of conversion of the starting materials, such as propylene, is small and the temperature of the catalyst layer Zout on the outlet side for gaseous starting materials may possibly exceed the upper limit temperature of use, resulting in a decrease in the yield of the reaction, a decrease in the lifetime of the catalyst and the risk of an uncontrolled reaction . Regarding the proposed method for solving this problem, it was found that in the method of using reaction tubes provided with a plurality of catalyst layers formed in the direction of the gaseous feed stream, the above-mentioned problem can be solved by developing a catalyst and technical conditions for loading the catalyst in such a way that the ratio between the degree of conversion starting materials, at which the yield of the desired product becomes maximum, and the degree of conversion of the starting materials in the case when the ratio of high / low at each of the maximum temperatures of the catalyst layer located on the furthest inlet side for the reaction gas and the catalyst layer located on the farthest outlet side for the reaction gas is reversed, satisfies these requirements, leading to the implementation of the present invention.

Specifically, the present invention relates to the following.

[one]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, the method includes:

the effect on propylene or at least one type of compounds selected from the group consisting of isobutylene and tertiary butanol, gas-phase contact oxidation using a gas containing molecular oxygen, using a fixed-bed multi-tube reactor,

where (A) a plurality of catalyst layers are proposed, formed by dividing the catalyst into N layers (N is an integer of 2 or more) in the direction of flow of the gaseous feed materials to the reaction tubes, and among the catalyst layers, a catalyst layer located at the nearest inlet side for the reaction gas, is defined as Zin, while the catalyst bed located on the farthest outlet side for the reaction gas is defined as Zout, and

(B) the catalyst is loaded so that the activity of the catalyst loaded in Zout is higher than the activity of the catalyst loaded in Zin and so that the following equation (1) is satisfied:

(1)0.5≤ (Cmax-Ccrs)

(one)

where Cmax represents the degree of conversion of the starting materials at which the yield of the desired product becomes maximum; and

Ccrs is the degree of conversion of the starting materials at which the high / low ratio between Tin and Tout is reversed when the maximum temperature of the catalyst layer Zin is determined as Tin and the maximum temperature of the catalyst layer Zin is determined as Tout and the degree of conversion of the starting materials is changed.

[2]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, as described in [1], above,

where the relationship {0.5≤ (Cmax-Ccrs) ≤10} is satisfied.

[3]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, as described in [1], above,

where the relationship {0.5≤ (Cmax-Ccrs) ≤5} is satisfied.

[four]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, as described above in any of [1] to [3],

where N is not more than 3,

the calcining temperature of the catalyst loaded in Zin is higher than the temperature of the catalyst loaded in Zout, and

a mixture of the catalyst and the molded mass of an inert substance is loaded into Zin.

[5]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, as described above in any of [1] to [4],

where the catalyst is a catalyst on a spherical carrier having an active powder on a carrier of an inert substance.

[6]

A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, as described above in any of [1] to [5],

where the particle diameter of the catalyst loaded into each of the catalyst layers is the same in all catalyst layers.

The effects of the invention

In accordance with the present invention, it is possible to prevent the occurrence of a phenomenon in which an industrial plant as a whole operates at a degree of conversion of the starting materials at which the yield becomes highest, unless there is a specific reason that the catalysts loaded into the plurality of reaction tubes act at the desired degree of conversion starting materials, and as a result, the temperature of the site of local overheating of the catalyst layer in the input part for gaseous starting materials is higher than the temperature of the site ka of local overheating of the catalyst on the output side for gaseous starting materials; however, due to the circumstances inherent in the industrial plant, there is a reaction tube in which the conversion of the starting materials is low, and as a result, with respect to the temperature of the catalyst loaded in the reaction tube, the temperature at the outlet side for gaseous starting materials is much higher than the temperature on the input side for gaseous starting materials, thereby causing an abnormal reaction. Thus, in accordance with the present invention, acrolein and acrylic acid or methacrolein and methacrylic acid can be produced safely and stably in high yield.

Of course, the simplicity or degree of generation of such a phenomenon varies depending on the composition or form of the catalyst, reaction conditions, and the like, and for this reason, cannot be unambiguously discussed. However, this phenomenon tends to become more and more problematic when the inner diameter of the reaction tube used is 25 mm or more, or when the molar ratio of water to hydrocarbon in gaseous feed materials is not more than 3.0.

The method of carrying out the invention

Next, preferred embodiments of the present invention are described.

The catalyst itself, which is used in the method of the present invention, can be obtained using the known method and is represented, for example, by the following general formula.

Mo _a Bi _b Ni _c Co _d Fe _f X _g Y _h O _x

In the above general formula, Mo, Bi, Ni, Co, Fe and O are molybdenum, bismuth, nickel, cobalt, iron and oxygen, respectively; X represents at least one element selected from the group consisting of tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium and titanium; Y represents at least one element selected from the group consisting of potassium, rubidium, thallium and cesium; and a, b, c, d, f, g, h and x represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, Y and oxygen, respectively, where a = 12, b = 0.1-7, preferably b = 0.5-4, (c + d) = 0.5-20, more preferably (c + d) = 1-12, f = 0.5-8, even more preferably f = 0 , 5-5, g = 0-2, particularly preferably g = 0-1, h = 0.005-2, most preferably h = 0.01-0.5, and x is a value determined by the oxidation state of each element .

Here, a powder containing a catalytically active component is obtained using a known method, such as a co-precipitation method and a spray drying method. When the resulting powder is preferably calcined at 200-600 ° C, and more preferably at 300-500 ° C, preferably in a stream of air or nitrogen gas, a catalytically active component can be obtained (hereinafter referred to as "pre-calcined powder").

Although the pre-calcined powder thus obtained can be used as a catalyst, as is, taking into account the production efficiency and processability, the pre-calcined powder is formed and then used as the catalyst of the present invention. The shape of the molded product is not in any way limited, including a spherical shape, a columnar shape, and an annular shape. Although the shape of the molded product should be selected, taking into account the production efficiency and mechanical strength of the catalyst, and the like, preferably, it is a spherical shape. In the case of molding, although it is generally accepted to use a single pre-calcined powder and its molding, separately prepared pre-calcined powders of granules having a different composition of components of iron, cobalt, nickel, alkali metals, and the like, can be pre-mixed in arbitrary proportions and molded. Alternatively, a technology may be adopted in which the operation of applying pre-calcined powder of various kinds onto an inert carrier is repeated, wherein the pre-calcined powders are formed in a plurality of layers. In this case, in the case of spinning, it is preferable to mix a spinning aid, such as crystalline cellulose, and / or a strength agent, such as a ceramic thread. The amount of molding aid and / or strength enhancer used is not more than 30% by weight, respectively, with respect to the pre-calcined powder. In addition, the molding aid and / or the strength enhancing agent may be premixed with the previously calcined powder above before molding, or may be added at the same time as the preliminary calcined powder is added to the molding machine or before or after it.

Although the molding method is not in any way limited, in the case of molding in the form of a columnar shape or an annular shape, a method using a tablet forming machine, an extrusion molding machine, or the like is preferred.

The case of spherical molding is more preferable. Although the pre-calcined powder can be spherically molded using a molding machine, a method in which a pre-calcined powder (containing a molding aid and a strength agent, if desired) is applied to a carrier such as an inert ceramic. As used herein, a method for applying to a carrier is not so limited as it is a granulation method using rolls, a method using a centrifugal flow coating device, or a method in which a pre-calcined powder can be uniformly applied to a carrier such as flushing. However, when the catalyst production efficiency or the like is taken into account, a method is preferred in which, in a device having a flat or irregular disk at the bottom of a fixed cylindrical container, the disk rotates at high speed while vigorously mixing the carrier loaded into a container, by repeatedly repeating the rotational movement of the carrier itself and the rotational movement of the disk, and a pre-calcined powder, and optionally an auxiliary substance a molding agent and a strength agent are added thereto, thereby depositing a powder component onto the carrier. In this case, in the case of coating, it is preferable to use a binder. Specific examples of a binder that can be used include water, ethanol, methanol, propanol, polyhydric alcohol, polyvinyl alcohol and a polymer-based binder, and an aqueous solution of a silica sol of an inorganic binder. Among them, ethanol, methanol, propanol and a polyhydric alcohol are preferred; a diol, such as ethylene glycol, a triol, such as glycerin, and the like, are preferred; and an aqueous solution of glycerol having a concentration of 5% of the mass. or more is preferred. When an appropriate amount of an aqueous solution of glycerol is used, the molding properties become good, and a catalyst with high performance can be obtained having high mechanical strength and high activity.

The amount of such a binder used is typically from 2 to 60 parts by weight with respect to 100 parts by weight of pre-calcined powder, and in the case of an aqueous glycerol solution, the amount of binder used is preferably from 10 to 30 parts by weight. In the case of applying to the carrier, the binder can be pre-mixed with pre-calcined powder or can be added at the same time by introducing pre-calcined powder into the roll granulator.

A carrier having a diameter of about 2 to 15 mm is typically used as an inert carrier, and a pre-calcined powder is applied to it. Its applied amount is determined taking into account the conditions of use of the catalyst, for example, hourly space velocity or the concentration of hydrocarbon starting materials.

The molded catalyst is calcined again before use in the reaction. In the case of re-calcination, the calcination temperature is usually from 450 to 650 ° C, and the calcination time is usually from 3 to 30 hours, and preferably from 4 to 15 hours. Both parameters are set appropriately depending on the reaction conditions to be used. This time, the calcination temperature of the catalyst, which is placed on the inlet side for the gaseous starting materials, is not based on its composition, and it is preferable to suppress the activity by calcining at a temperature higher than the temperature of the catalyst on the outlet side for the gas. Although the calcination atmosphere may be any atmosphere from an air atmosphere, a nitrogen atmosphere or the like, from an industrial point of view, an air atmosphere is preferred.

Thus, the obtained catalyst can be used for the stage of exposure to propylene gas-phase contact oxidation using molecular oxygen or using a gas containing molecular oxygen to obtain acrolein and acrylic acid, or the stage of exposure to isobutylene and / or tertiary butanol gas-phase contact oxidation using molecular oxygen or using a gas containing molecular oxygen to produce methacrolein and methacrylic acid. In the production method of the present invention, the method of flowing gaseous feedstocks can be either a general simple flow method or a recycling method, and it can be carried out under generally accepted conditions and is not in any way limited. For example, the reaction is carried out by introducing a gas mixture, preferably consisting of 1-10% volume, and more preferably 4-9% volume of propylene, isobutylene or tertiary butanol, as raw materials, preferably 3-20% volume, and more preferably, from 4-18% volume of molecular oxygen, preferably from 0-60% volume, and more preferably from 4-50% volume of water vapor, and preferably from 20-80% volume, and more preferably 30-60 % volume of inert gas, such as carbon dioxide and nitrogen, at ordinary temperature at atalizatore the present invention is loaded into the reaction tube at 250-450 ° C, at a pressure of from atmospheric pressure to 10 atm., at a volumetric hour velocity between 300 and 5000 h ^-1. You can carry out the above reaction using one single type of catalyst for the catalyst layer. However, in accordance with the method of the present invention, the temperature of the local superheat section can be reduced by establishing catalyst layers obtained separately in an amount of N (N is an integer of 2 or more).

Then, in the method of the present invention, among the catalyst layers obtained separately, in the direction of flow of the gaseous feed materials of the reaction tubes, the catalyst layer located on the most inlet side for the reaction gas is defined as Zin, while the catalyst layer located on the the far side for the reaction gas is defined as Zout, and the catalyst is charged so that the activity of the catalyst loaded in Zout is higher than the activity of the catalyst loaded in Zin, that satisfies the following equation (1):

(1)0.5≤ (Cmax-Ccrs)

(one)

where Cmax represents the degree of conversion of the starting material at which the yield of the desired product becomes maximum; and Ccrs is the degree of conversion of the starting material in which the high / low ratio between Tin and Tout is reversed when the maximum temperature of the catalyst layer Zin is defined as Tin and the maximum temperature of the catalyst layer Zin is determined as Tout, and the degree of conversion of the starting materials is changed.

In equation (1), a ratio of {0.5≤ (Cmax-Ccrs) ≤10} is preferred, and a ratio of {0.5≤ (Cmax-Ccrs) ≤5} is more preferred.

In more detail, the composition, the calcination temperature, the proportion of mixing with an inert substance and the loading length of the catalyst on the inlet side for gaseous starting materials, and the composition, the calcination temperature, and the loading length of the catalyst on the inlet side for gaseous starting materials are determined so that the ratio { 0.5≤ (Cmax-Ccrs)}. In this case, although (Cmax-Ccrs) also varies depending on the running time, to demonstrate the effects of the present invention, it is preferable that the ratio {0.5≤ (Cmax-Ccrs)} be satisfied within one year after starting to use the catalyst , and preferably, before replacing the catalyst. This is due to the fact that in the catalyst immediately after the start of use, the conversion of the starting materials becomes small, in particular, the Zout value tends to increase. In addition to this, as a rule, there is a tendency that (Cmax-Ccrs) becomes small due to the deterioration of the catalyst loaded in Zin over time. Accordingly, by developing technical loading conditions such that (Cmax-Ccrs) is a value greater than 0.5, and preferably 1 or more, at the time the reaction begins, its level, however, varies depending on the catalyst used, the effects of the present invention can be maintained for an extended period of time. Regarding the preceding discussion, it is preferable to determine the loading condition of the catalyst using an experimental device that can be tested under the same conditions before being used in an industrial plant, and it is also possible to use computer simulation in combination with this.

In computer simulation, it is common to use CFD (Computational Fluid Dynamics (Computational Fluid Dynamics)). By entering data, such as the physical properties of the catalyst used, the reaction rate constant and the heat of reaction, into commercially available software and performing calculations, it is possible to calculate the degree of conversion of the starting materials, the yields of acrolein and acrylic acid or the like, and the temperature distribution in the catalyst layer under the desired reaction conditions.

When determining Cmax and Ccrs in an industrial installation or experimental device, the non-uniform distribution of the temperature of the catalyst layer is measured with a measurement width of 10 cm or less using a thermocouple. When the measurement is carried out with a measurement width of more than 10 cm, then there is the problem that the temperature of the local superheat section cannot be detected accurately, and therefore this is not preferred. In addition, regarding the degree of conversion of gaseous starting materials, Cmax and Ccrs are determined by intentionally changing the temperature of the reaction bath to measure the degree of conversion of the starting materials at each temperature of the reaction bath, the yield of the active component at each degree of conversion of the starting materials, and the temperature of the local overheating section, s plotting and then interpolating the data. By changing the temperature of the reaction bath and with a measurement width of less than 5 ° C, more accurate data can be obtained.

In accordance with the present invention, if the ratio {0.5≤ (Cmax-Ccrs)} is satisfied, even if there is a deviation in the reaction temperature inside the reactor in an industrial plant, a deviation in the state of the gas flow or a deviation in the pressure drop in each reaction tube, the occurrence of a phenomenon can be prevented at which the temperature of the local overheating section (namely, Tout) of the catalyst on the outlet side for gaseous starting materials becomes extremely high in essentially all reaction tubes, and thus ohms, it becomes possible to secure a stable and implementation of the operation. In addition, if the ratio {(Cmax-Ccrs) ≤5} is satisfied, there is a tendency that Tin can be controlled at a relatively low temperature.

As described previously, although delicate adjustment of the catalyst loading specifications is required depending on the operating conditions, in accordance with the present invention, making the calcining temperature during preparation of the catalyst to be used on the inlet side for gaseous feed materials higher than the calcining temperature during preparing a catalyst to be used on the outlet side for gas, and diluting the gaseous starting materials with an inert substance, It is possible to relatively easily change the loading specifications.

EXAMPLES

The present invention is described more specifically below with reference to the following Examples, but it is not necessary to assume that the present invention is limited to these Examples.

In this case, the degree of conversion, selectivity and yield of the present invention are determined, respectively, as follows.

The degree of conversion of propylene (% mol) = {(number of moles of reacted propylene) / (number of moles of introduced propylene)} × 100

acrolein yield (% mol) = {(number of moles of formed acrolein) / (number of moles of introduced propylene)} × 100

yield of acrylic acid (% mol) = {(number of moles of formed acrylic acid) / (number of moles of introduced propylene)} × 100

In the case where the starting materials are isobutylene and / or tertiary butanol, instead of propylene, acrolein can be replaced by methacrolein and acrylic acid can be replaced by methacrylic acid.

Example 1

(Preparation of catalyst)

423.8 parts by weight of ammonium molybdate and 1.64 parts by weight of potassium nitrate are dissolved in 3000 parts by weight of distilled water by heating and stirring to obtain an aqueous solution (A1). Separately, 302.7 parts by weight of cobalt nitrate, 162.9 parts by weight of nickel nitrate and 145.4 parts by weight of iron (III) nitrate are dissolved in 1000 parts by weight of distilled water to obtain an aqueous solution (B1). Also, 164.9 parts by weight of bismuth nitrate are dissolved in 200 parts by weight of distilled water, which is acidified by adding 42 parts by weight of concentrated nitric acid to give an aqueous solution (C1). The above aqueous solution (A1) is successively mixed with aqueous solutions (B1) and (C1) with vigorous stirring, and the formed liquid suspension is dried using a spray drying apparatus and calcined at 440 ° C. for 6 hours, to thereby preliminarily calcined powder (D1). This time, the compositional ratio of the catalytically active components excluding oxygen is Mo = 12, Bi = 1.7, Ni = 2.8, Fe = 1.8, Co = 5.2, and K = 0.15, respectively in terms of atomic ratio.

After that, the powder obtained by mixing 100 parts by mass of pre-calcined powder with 5 parts by mass of crystalline cellulose is controlled by weight with respect to the inert carrier to be used for molding (a spherical substance consisting mainly of alumina and silica and having a diameter of 4.5 mm), and to the mass of pre-calcined powder in such a proportion that the amount applied to the carrier is 50% of the mass. 20% of the mass of an aqueous solution of glycerol is used as a binder, and the resulting substance is deposited on a carrier and molded in the form of spheres having a diameter of 5.2 mm to obtain a supported catalyst (E1).

The supported catalyst (E1) was calcined in an air atmosphere at a calcination temperature of 530 ° C. for 4 hours, to thereby obtain a catalyst (F1).

Then, 423.8 parts of the mass of ammonium molybdate and 1.08 parts of the mass of potassium nitrate are dissolved in 3000 parts of the mass of distilled water by heating and stirring, thereby obtaining an aqueous solution (A2). Separately, 302.7 parts by weight of cobalt nitrate, 162.9 parts by weight of nickel nitrate and 145.4 parts by weight of iron nitrate are dissolved in 1000 parts by weight of distilled water to obtain an aqueous solution (B2). Also, 164.9 parts by weight of bismuth nitrate are dissolved in 200 parts by weight of distilled water, which is acidified by adding 42 parts by weight of concentrated nitric acid to give an aqueous solution (C2). The above aqueous solution (A2) is sequentially mixed with aqueous solution (B2) and (C2) with vigorous stirring, and the formed liquid suspension is dried using a spray drying apparatus and calcined at 440 ° C. for 6 hours, to thereby preliminarily calcined powder (D2). This time, the compositional ratio of catalytically active components excluding oxygen is Mo = 12, Bi = 1.7, Ni = 2.8, Fe = 1.8, Co = 5.2, and K = 0.10, respectively, in terms of atomic ratio.

After that, the powder obtained by mixing 100 parts by mass of pre-calcined powder with 5 parts by mass of crystalline cellulose is controlled by weight with respect to the inert carrier to be used for molding (a spherical substance consisting mainly of alumina and silica and having a diameter of 4.5 mm), and to the mass of pre-calcined powder in such a proportion that the amount applied to the carrier is 50% of the mass. 20% of the mass of an aqueous solution of glycerol is used as a binder, and the resulting substance is deposited on a carrier and molded in the form of spheres having a diameter of 5.2 mm to obtain a supported catalyst (E2).

The supported catalyst (E2) was calcined in an atmosphere of air at a calcination temperature of 530 ° C. for 4 hours, thereby obtaining a catalyst (F2). The supported catalyst (E2) was calcined at 510 ° C. for 4 hours to obtain a catalyst (F3).

(Study of the oxidation reaction)

On the input side for the gaseous starting materials of a reactor made of stainless steel having an internal diameter of 25.4 mm, in which a casing is installed on the axis of the tube for circulating molten salt as a heated medium and a thermocouple for measuring the temperature of the catalyst layer is loaded, namely below the order, spheres of silicon oxide-alumina having a diameter of 5.2 mm to a depth of 20 cm, a diluted catalyst as the first layer of an oxidation catalyst (on the input side for the gaseous source material) to a depth of 100 cm, which is prepared by mixing an oxidation catalyst (F1) and an inert support from a mixture of silicon oxide-alumina having a diameter of 5.2 mm, with a mass ratio of 4/1 and an oxidation catalyst (F3) as the second layer the oxidation catalyst (on the gas output side) to a depth of 250 cm, and the temperature of the reaction bath is set at 330 ° C. A gas in which the injected amounts of propylene, air, nitrogen and water are set to obtain a molar ratio of the starting materials propylene / oxygen / nitrogen / water 1 / 1.7 / 8.8 / 1, is introduced at a space velocity of 1500 h ^-1 in the oxidation reactor , and the outlet pressure of the reactor is set at 70 kPa in the sensor. 200 hours after the start of the reaction, a study is carried out to measure the degree of conversion of the starting materials, the yield of acrolein and acrylic acid, and the temperature of the local overheating area (hereinafter referred to as the “study with a change in the reaction temperature”), changing the temperature of the reaction bath at intervals of 2 ° C. As a result, the total yield of acrolein and acrylic acid is 91.8% at maximum with a conversion of starting materials of 97.8%. This time, at a reaction bath temperature of 330 ° C, the temperature of the local overheating section of the catalyst layer on the gas inlet side is 434 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 378 ° C. In addition to this, the high / low ratio between these two temperatures of the local superheat section is reversed when the degree of conversion of the starting materials is 95.5%. That is (Cmax-Ccrs) is 2.3. At a reaction bath temperature of 320 ° C, although the propylene conversion is 93%, the temperature of the local overheating of the catalyst layer on the gas inlet side is 352 ° C and the temperature of the local overheating of the catalyst layer on the gas inlet side is 401 ° C. Thus, it is shown that even in the case where the degree of conversion of propylene is significantly reduced, the temperature of the local overheating section of the catalyst layer on the gas outlet side does not become extremely high; and that work can be stably carried out over an extended period of time.

Example 2

The propylene oxidation reaction is carried out in the same manner as in Example 1, except that under the conditions of the oxidation reaction of Example 1, the catalyst to be loaded in the inlet for gaseous starting materials is replaced with a diluted catalyst obtained by mixing catalyst F2 and an inert a carrier of a mixture of silicon oxide-alumina having a diameter of 5.2 mm, with a mass ratio of 4/1 to a depth of 120 cm; and the catalyst to be loaded into the gaseous feed outlet is replaced by catalyst F3 to a depth of 230 cm.

Carry out a study with a change in the reaction temperature. As a result, the total yield of acrolein and acrylic acid is 92.1% at maximum with a conversion of starting materials of 97.2%. This time, at a reaction bath temperature of 332 ° C, the temperature of the local overheating section of the catalyst layer on the gas inlet side is 431 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 372 ° C. In addition to this, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of the starting materials is 95.1%. That is (Cmax-Ccrs) is 2.1. At a reaction bath temperature of 322 ° C, although the propylene conversion is 93%, the temperature of the local overheating of the catalyst layer on the gas inlet side is 353 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 398 ° C. Thus, it is shown that even in the case where the propylene conversion is significantly reduced, the temperature of the local overheating of the catalyst layer on the gas outlet side does not become extremely high; and that work can be stably carried out over an extended period of time.

Example 3

The study is carried out in the same manner as in Example 2, except that in Example 2, a gas in which the injected amounts of propylene, air, nitrogen and water is set to obtain a molar ratio of the starting materials propylene / oxygen / nitrogen / water 1/1 , 8/10 / 1,5, is introduced into the oxidation reactor at a space velocity of 1500 h ^-1 ; and the outlet pressure of the reactor is set at 55 kPa in the sensor. As a result, the total yield of acrolein and acrylic acid is 92.3% at maximum with a conversion of starting materials of 97.9%. This time, at a reaction bath temperature of 330 ° C, the temperature of the local overheating portion of the catalyst layer on the gas inlet side is 424 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 370 ° C. In addition, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of the starting materials is 96.2%. That is (Cmax-Ccrs) is 1.7. At a reaction bath temperature of 318 ° C, although the propylene conversion is 95%, the temperature of the localized superheat of the catalyst layer on the gas inlet side is 348 ° C, and the temperature of the localized superheat of the catalyst layer on the gas inlet side is 410 ° C. Thus, it is shown that even in the case where the propylene conversion is significantly reduced, the temperature of the local overheating of the catalyst layer on the gas outlet side does not become extremely high; and that work can be stably carried out over an extended period of time.

Example 4

The study is carried out in the same manner as in Example 3, except that in Example 3, the gas is introduced into the oxidation reactor at a space velocity of 1.715 h ^-1 ; and the outlet pressure of the reactor is set at 70 kPa in the sensor. As a result, the total yield of acrolein and acrylic acid is 91.6% at maximum with a conversion of starting materials of 97.8%. This time, at a reaction bath temperature of 332 ° C, the temperature of the local overheating section of the catalyst layer on the gas inlet side is 429 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 371 ° C. In addition, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of the starting materials is 96.1%. That is (Cmax-Ccrs) is 1.7. At a reaction bath temperature of 319 ° C, although the propylene conversion is 95%, the temperature of the local overheating portion of the catalyst layer on the gas inlet side is 350 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 414 ° C. Thus, it is shown that even in the case where the propylene conversion is significantly reduced, the temperature of the local overheating of the catalyst layer on the gas outlet side does not become extremely high; and that work can be stably carried out over an extended period of time.

Example 5

The study is carried out in the same manner as in Example 2, except that in Example 2, the gas in which the injected amounts of propylene, air, nitrogen and water are set to obtain a molar ratio of the starting materials propylene / oxygen / nitrogen / water 1/1 , 9/12/1, is introduced into the oxidation reactor at a space velocity of 2000 h ^-1 ; the outlet pressure of the reactor is set at 65 kPa in the sensor, and the desired product is acrolein. As a result, the yield of acrolein is 85.2% at maximum with a conversion of starting materials of 96.5%. This time, at a reaction bath temperature of 334 ° C, the temperature of the local overheating portion of the catalyst layer on the gas inlet side is 420 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 385 ° C. In addition to this, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of the starting materials is 95.5%. That is (Cmax-Ccrs) is 1.0. At a reaction bath temperature of 326 ° C., although the propylene conversion is 94%, the temperature of the localized superheat of the catalyst layer on the gas inlet side is 347 ° C, and the temperature of the localized superheat of the catalyst layer on the gas inlet side is 415 ° C. Thus, it is shown that even in the case where the propylene conversion is significantly reduced, the temperature of the local overheating of the catalyst layer on the gas outlet side does not become extremely high; and it is possible to stably carry out work over an extended period of time.

Example 6

On the input side, for the gaseous starting materials of a stainless steel reactor having an inner diameter of 27.2 mm, in which a casing is installed on the tube axis for circulating molten salt as a heating medium, and a thermocouple for measuring the temperature of the catalyst layer is loaded in the following order spheres of silicon oxide-alumina having a diameter of 5.2 mm to a depth of 20 cm, a diluted catalyst as the first layer of an oxidation catalyst (on the input side for gaseous feed m at a depth of 100 cm, which is obtained by mixing an oxidation catalyst (F1) and an inert support from a mixture of silicon oxide-alumina having a diameter of 5.2 mm, with a mass ratio of 3/1, and an oxidation catalyst (F3) as the second the oxidation catalyst layer (on the gas outlet side) to a depth of 210 cm, and the temperature of the reaction bath is set at 325 ° C. A gas in which the injected amounts of propylene, air, nitrogen and water are set to obtain a molar ratio of the starting materials propylene / oxygen / nitrogen / water 1 / 1.7 / 8.8 / 1, is introduced into the oxidation reactor at a space velocity of 1250 h ^-1 and the outlet pressure of the reactor is set at 50 kPa in the sensor. After 200 hours after the start of the reaction, a study is carried out with a change in the reaction temperature, while changing the temperature of the reaction bath at 2 ° C intervals. As a result, the total yield of acrolein and acrylic acid is 91.5% at maximum with a conversion of starting materials of 97.8%. This time, at a reaction bath temperature of 322 ° C, the temperature of the local overheating portion of the catalyst layer on the gas inlet side is 424 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 373 ° C. In addition to this, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of the starting materials is 96.6%. That is (Cmax-Ccrs) is 1.2. At a reaction bath temperature of 310 ° C, although the propylene conversion is 92%, the temperature of the local overheating of the catalyst layer on the gas inlet side is 330 ° C, and the temperature of the local overheating of the catalyst layer on the gas inlet side is 400 ° C. Thus, it is shown that even in the case where the conversion of propylene is significantly reduced, the temperature of the local overheating section of the catalyst layer on the gas outlet side does not become extremely high; and that work can be stably carried out over an extended period of time.

Comparative Example 1

The propylene oxidation reaction is carried out in the same manner as in Example 1, except that under the conditions of the oxidation reaction of Example 1, the catalyst to be loaded into the inlet for gaseous starting materials is replaced with a diluted catalyst obtained by mixing catalyst F3 and an inert a carrier from a mixture of silicon oxide-alumina having a diameter of 5.2 mm, with a mass ratio of 2/1 to a depth of 100 cm; and the catalyst, which should be loaded into the outlet for gaseous starting materials, is replaced by the catalyst F3 to a depth of 250 cm. As a result of the study with a change in the reaction temperature, the total yield of acrolein and acrylic acid is 91.9% at maximum when converting the starting materials 98 ,5%. This time, at a reaction bath temperature of 335 ° C., the temperature of the local overheating section of the catalyst layer on the gas inlet side is 418 ° C., and the temperature of the local overheating of the catalyst layer on the gas inlet side is 380 ° C. In addition, the high / low ratio between the two temperatures of the local superheat section is reversed when the conversion of starting materials is 98.2%. That is (Cmax-Ccrs) is 0.3. At a reaction bath temperature of 326 ° C, the propylene conversion is 95.5%, the temperature of the local overheating of the catalyst layer on the gas inlet side is 358 ° C, and the temperature of the local overheating of the catalyst layer on the gas outlet side is 445 ° C. Compared to the Examples, in the case where the conversion of propylene is significantly reduced, the temperature of the local overheating section of the catalyst layer on the gas outlet side becomes extremely high.

Although the present invention is described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from its spirit and scope.

In this case, the present application is based on the Japanese Patent Application filed on July 20, 2012 (Japanese Patent Application No. 2012-161353), which is incorporated by reference in its entirety. In addition to this, all references cited in this document are included as a whole.

[Industrial application]

In accordance with the present invention, it is possible to safely and stably produce acrolein and acrylic acid, or methacrolein and methacrylic acid in high yield.

Claims (29)

1. A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid, including: the effect on propylene or at least one type of compounds selected from the group consisting of isobutylene and tertiary butanol in the form of gas-phase contact oxidation using a gas containing molecular oxygen using a fixed-bed multi-tube reactor, where (A) provide a plurality of catalyst layers formed by dividing the catalyst layer into N layers (N is an integer of 2 or more) in the direction of flow of the gaseous feed materials in the reaction tubes, and among the catalyst layers, that catalyst layer located on the nearest inlet side for the reaction gas is defined as Zin, while the catalyst bed located on the farthest outlet side for the reaction gas is defined as Zout, and (B) the catalyst is loaded so that the activity of the catalyst loaded in Zout is higher than the activity of the catalyst loaded in Zin, and so that the following equation (1) is satisfied:

where Cmax represents the degree of conversion of the starting materials at which the yield of the desired product becomes maximum; and Ccrs is the degree of conversion of the starting materials, in which the high / low ratio between Tin and Tout is reversed when the maximum temperature of the catalyst layer Zin is defined as Tin and the maximum temperature of the catalyst layer Zin is determined as Tout, and the degree of conversion of the starting materials is changed. 2. A method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 1, where the relationship {0.5≤ (Cmax-Ccrs) ≤10} is satisfied. 3. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 1, where the relationship {0.5≤ (Cmax-Ccrs) ≤5} is satisfied. 4. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 1, where N is not more than 3, the calcination temperature of the catalyst loaded in Zin is higher than the calcination temperature of the catalyst loaded in Zout, and a mixture of a catalyst and an inert substance molded mass is charged into Zin. 5. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 2, where N is not more than 3, the calcination temperature of the catalyst loaded in Zin is higher than the calcination temperature of the catalyst loaded in Zout, and a mixture of a catalyst and an inert substance molded mass is charged into Zin. 6. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 3, where N is not more than 3, the calcination temperature of the catalyst loaded in Zin is higher than the calcination temperature of the catalyst loaded in Zout, and a mixture of a catalyst and an inert substance molded mass is charged into Zin. 7. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to any one of paragraphs. 1-6, where the catalyst is a catalyst on a spherical carrier having an active powder on a carrier of an inert substance. 8. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to any one of paragraphs. 1-6, where the particle diameter of the catalyst loaded into each of the catalyst layers is the same across all catalyst layers. 9. The method of producing acrolein and acrylic acid or methacrolein and methacrylic acid according to claim 7, where the particle diameter of the catalyst loaded into each of the catalyst layers is the same across all catalyst layers.