JP2009263352A - Method for producing at least one of reaction product selected from group consisting of unsaturated aliphatic aldehyde, unsaturated hydrocarbon, and unsaturated fatty acid using fixed bed type reactor having catalyst comprising molybdenum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method for production by which deterioration of a catalyst caused by an excessive reaction of reaction raw materials, and sublimation of a molybdenum component composing the catalyst in the presence of steam are suppressed without lowering the yield and selectivity etc., for the objective reaction product in the method for production comprising subjecting a reaction raw material gas to a catalytic vapor-phase oxidation with an oxygen-containing gas, and producing the reaction product by using a fixed bed type reactor having the catalyst comprising molybdenum. <P>SOLUTION: The method for production comprises subjecting the reaction raw material gas to the catalytic vapor-phase oxidation reaction with the oxygen-containing gas in the presence of the steam, and producing the reaction product by using the fixed bed type reactor having the catalyst comprising the molybdenum. The method for production is characterized by starting the feed of the steam so as to provide ≥2.0 kPa steam partial pressure in the whole gas fed to the reactor, and subsequently starting the feed of the reaction raw material gas when starting up the reactor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a process for producing a reactant by using a fixed bed reactor equipped with a catalyst containing molybdenum and subjecting a reaction raw material gas to gas-phase oxidation with an oxygen-containing gas in the presence of water vapor. Regarding the method.

  Methacrylic acid and acrylic acid, as well as methacrolein and acrolein are produced by a process using a catalytic gas phase oxidation reaction in which propylene, propane, isobutylene, or methacrolein or acrolein is contacted with molecular oxygen in the presence of a catalyst. . Butadiene is produced by a method using an oxidative dehydrogenation reaction in which butene and molecular oxygen are contacted in the presence of a catalyst. And in the method using these catalytic gas phase oxidation reactions, a fixed bed type reaction provided with a catalyst such as a multi-tubular reactor or a plate type catalyst layer reactor (for example, Patent Document 1 and Patent Document 2). A vessel is used.

In order to safely perform catalytic gas phase oxidation of a combustible reaction source gas such as propylene, propane, isobutylene, methacrolein, acrolein, or butene in the presence of oxygen, it is necessary to avoid the explosion range of the reaction source gas. As a diluent used to avoid the explosion range, water vapor is used in the same manner as nitrogen, carbon dioxide, and argon.
On the other hand, in the method for producing acrolein and acrylic acid by catalytic vapor phase oxidation of propylene and the like and the method for producing butadiene by oxidative dehydrogenation of butene, a composite oxide catalyst containing molybdenum is usually used. ing.
In the catalytic gas phase oxidation reaction using the composite oxide catalyst, the amount of oxygen in the gas phase that affects the oxidation state of the catalyst is important, and an excess of oxygen is present in comparison with the stoichiometric amount of the normal reaction. However, excess oxygen promotes side reactions and causes the formation of by-products and even heavier carbons with a high carbon content, and ultimately causes coking of the catalyst layer. On the other hand, the water molecules contained in the water vapor reduce the concentration of oxygen and reaction raw materials and promote the desorption of the adsorbate on the catalyst, thereby suppressing side reactions and suppressing the generation of by-products and carbon. For example, Patent Document 3 states that in a catalyst containing molybdenum, water vapor is the most desirable diluent in terms of reaction conversion and selectivity.
However, in the composite oxide catalyst containing molybdenum, when water vapor is present in the reaction system, the molybdenum component constituting the catalyst is easily sublimated. In the composite oxide catalyst, when the molybdenum component constituting the catalyst is sublimated, the catalyst is deteriorated and the yield of the reaction product is reduced. In order to solve this problem, Patent Document 4 uses a plurality of types of molybdenum-bismuth-iron composite oxide catalysts in which the Fe / (Co + Ni) ratio is constant and the amounts of Co and Ni are changed. By filling the reactor so that the amount ratio of Co / (Co + Ni) of multiple types of complex oxide catalysts decreases from the source gas inlet side to the outlet side of the reactor, the reactor has two or more reaction zones. A method for carrying out an oxidation reaction of propylene is proposed.

JP 2004-167448 A JP 2004-202430 A US Pat. No. 3,475,488 JP 2003-146920 A

  The present invention has been made in view of the above circumstances, and its object is to use a fixed bed reactor equipped with a catalyst containing molybdenum, and to react a reaction raw material gas with an oxygen-containing gas. In the production method of producing a reactant by phase oxidation, the degradation of the catalyst due to the excessive reaction of the reaction raw materials and the sublimation of the molybdenum component constituting the catalyst in the presence of water vapor are suppressed, and the target reactant is collected. It is an object of the present invention to provide a novel production method that does not reduce the rate and selectivity.

[1] Using a fixed bed reactor equipped with a catalyst containing molybdenum, at least one kind of a reaction raw material gas selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol, or At least one reaction raw material gas selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms is subjected to catalytic gas phase oxidation using an oxygen-containing gas in the presence of water vapor to obtain 3 and 4 carbon atoms. In the production method for producing at least one reactant selected from the group consisting of unsaturated aliphatic aldehydes, unsaturated hydrocarbons and unsaturated fatty acids having 3 and 4 carbon atoms, when the reactor is started up, the reaction The supply of the reaction raw material gas is started after the supply of water vapor is started so that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more. A production method for producing at least one reactant selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms, unsaturated hydrocarbons and unsaturated fatty acids having 3 and 4 carbon atoms.
[2] When starting up the reactor, after starting the supply of water vapor so that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more, the reaction raw material is received in less than 5 hours Gas supply is started, The manufacturing method as described in [1] characterized by the above-mentioned.
[3] The start-up is a time when the reactor is started up, the reactant is manufactured for a certain period, the reactor is shut down, and then the reactor is restarted. [1] or [2].
[4] When at least one reaction raw material gas selected from the group consisting of the hydrocarbons having 3 and 4 carbon atoms and tertiary butanol is subjected to catalytic gas phase oxidation using an oxygen-containing gas in the presence of water vapor. The production method according to any one of [1] to [3], wherein the catalyst is composed of a metal oxide represented by the following general formula (1).
Mo (a) Bi (b) Co (c) Ni (d) Fe (e) X (f) Y (g) Z (h) Q (i) Si (j) O (k) (1) )
(In the above formula (1), Mo is molybdenum, Bi is bismuth, Co is cobalt, Ni is nickel, Fe is iron, X is at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium, Y is at least one element selected from the group consisting of boron, phosphorus, arsenic and tungsten, Z is at least one element selected from the group consisting of magnesium, calcium, zinc, cerium and samarium, Q is a halogen element, and Si is Silica, O represents oxygen, and a, b, c, d, e, f, g, h, i, j, and k are Mo, Bi, Co, Ni, Fe, X, Y, Z, Q represents the atomic ratio of Si and O, and when the molybdenum atom (Mo) is 12, 0.5 ≦ b ≦ 7, 0 ≦ c ≦ 10, 0 ≦ d ≦ 10, 1 ≦ c + d ≦ 10, 0. 5 ≦ e ≦ 3, 0.0005 ≦ f ≦ 3, 0 ≦ g ≦ 3, 0 ≦ h ≦ 1, 0 ≦ i ≦ 0.5, 0 ≦ j ≦ 40, and k depends on the oxidation state of each element. (The value is determined.)
[5] Catalyst for catalytic gas phase oxidation of at least one reaction raw material gas selected from the group consisting of the unsaturated aliphatic aldehydes having 3 and 4 carbon atoms using an oxygen-containing gas in the presence of water vapor Is made of a metal oxide represented by the following general formula (2), The production method according to any one of [1] to [3].
Mo (12) V (a) X (b) Cu (c) Y (d) Sb (e) Z (f) Si (g) C (h) O (i) (2)
(In the above formula (2), X represents at least one element selected from the group consisting of Nb and W. Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba and Zn. Z represents at least one element selected from the group consisting of Fe, Co, Ni, Bi, and Al, provided that Mo, V, Nb, Cu, W, Sb, Mg, Ca, Sr, Ba, Zn, Fe, Co, Ni, Bi, Al, Si, C and O are element symbols.
Further, a, b, c, d, e, f, g, h and i represent atomic ratios of the respective elements, and 0 <a ≦ 12, 0 ≦ b ≦ 12 with respect to the molybdenum atom (Mo) 12, 0 ≦ c ≦ 12, 0 ≦ d ≦ 8, 0 ≦ e ≦ 500, 0 ≦ f ≦ 500, 0 ≦ g ≦ 500, 0 ≦ h ≦ 500, and i is each of the above components except C The value is determined by the degree of oxidation of the component. )
[6] The hydrocarbon having 3 carbon atoms is propylene or propane, the hydrocarbon having 4 carbon atoms is isobutylene, 1-butene, isobutane, or butane, and the unsaturated hydrocarbon having 3 or 4 carbon atoms. [1] to [5], wherein the aliphatic aldehyde is acrolein or methacrolein, the unsaturated hydrocarbon is butadiene, and the unsaturated fatty acid having 3 and 4 carbon atoms is acrylic acid or methacrylic acid. ] The manufacturing method as described in any one of.
[7] The fixed bed reactor according to any one of [1] to [6], wherein the fixed-bed reactor is a multitubular reactor including a reaction tube, and the inner diameter of the reaction tube is 10 to 50 mm. Manufacturing method.
[8] The fixed bed reactor is a plate reactor including a catalyst layer formed between heat transfer plates, and the plate reactor includes a plurality of reactions having different catalyst layer thicknesses. The production according to any one of [1] to [6], wherein the production is a plate reactor that is divided into zones, and is supplied with a heat medium whose temperature is independently adjusted to the plurality of reaction zones. Method.

  According to the present invention, in a production method for producing a reaction product by using a fixed bed reactor equipped with a catalyst containing molybdenum and subjecting a reaction raw material gas to catalytic gas phase oxidation using an oxygen-containing gas. It is possible to provide a novel production method that suppresses catalyst deterioration due to excessive reaction of reaction raw materials and sublimation of a molybdenum component constituting the catalyst in the presence of water vapor and does not reduce the selectivity of a target reactant. Is possible.

The schematic sectional drawing of a multitubular reactor is shown. The schematic sectional drawing of the multitubular reactor which divided | segmented the shell with the intermediate tube sheet is shown. The longitudinal cross-sectional view of a plate type reactor is shown. The longitudinal cross-sectional view of a plate type reactor is shown. The enlarged view of a heat-transfer plate is shown.

In the start-up of the process of catalytic gas phase oxidation of a reaction raw material gas such as propylene using a fixed bed reactor equipped with a catalyst containing molybdenum, an oxygen-containing gas is generally used to avoid the explosion range of the reaction raw material. After the supply amount of inert gas (diluent) such as nitrogen (for example, air) and nitrogen is adjusted, supply of propylene as a reaction raw material is started. Here, at the time of start-up of the process, the ratio of the oxygen concentration to the propylene concentration becomes larger than the setting, and an excessive reaction is likely to occur.
The inventors of the present application are inadequate to use an inert gas such as nitrogen or carbon dioxide for the suppression of this excessive reaction, and desorb the adsorbent of the catalyst before starting the supply of the reaction raw material gas. It has been found that it is important to supply water vapor in a specific condition that also has a promoting effect to the catalyst in advance.

On the other hand, in the case of a catalyst containing molybdenum as described above, when water vapor is present in the reaction system, the molybdenum component constituting the catalyst is likely to sublime, and when the molybdenum component constituting the catalyst is sublimated, the catalyst deteriorates and the reactant Decreases in yield and selectivity.
As a solution to this problem, a method of using a plurality of types of molybdenum-bismuth-iron-based composite oxide catalysts and dividing the reactor into two or more reaction zones as disclosed in JP-A-2003-146920 There is also. However, since this method uses a plurality of types of catalysts and divides the inside of the reactor into two or more reaction zones, there is an increase in catalyst cost and time and effort in filling the catalyst. Therefore, development of a simpler method at lower cost has been desired.

On the other hand, the production method of the present invention uses a fixed bed reactor equipped with a catalyst containing molybdenum, and a reaction selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol. Contact gas phase using at least one kind of source gas or at least one kind of reaction source gas selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms using oxygen-containing gas in the presence of water vapor In the production method for producing at least one reactant selected from the group consisting of an unsaturated aliphatic aldehyde having 3 and 4 carbon atoms, an unsaturated hydrocarbon, and an unsaturated fatty acid having 3 and 4 carbon atoms by oxidation, the reaction When starting up the reactor, after starting the supply of water vapor so that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more, Characterized by starting the supply of gas.
The present inventors have determined that the sublimation rate of molybdenum greatly depends not only on the water vapor concentration and water vapor supply amount in the supply gas but also on the partial pressure of water vapor. It was found that the partial pressure of water vapor in the feed gas determined from the operating pressure of the reactor was important.
The water vapor partial pressure is preferably 3.0 kPa or more, and more preferably 5.0 kPa or more. On the other hand, from the viewpoint of preventing molybdenum sublimation, the water vapor partial pressure is preferably 50.0 kPa or less.

Further, since the sublimation amount of molybdenum is affected by the sublimation speed and the contact time of water vapor, it is particularly preferable to adjust the water vapor partial pressure in the supply gas and the time until the reaction raw material gas is supplied. Therefore, in the production method of the present invention, when starting up a fixed bed reactor equipped with a catalyst containing molybdenum, the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more. In a preferred embodiment, the supply of the reaction raw material gas is started in less than 5 hours after the supply of water vapor is started.
This aspect is a simpler method at a lower cost than the method described in Japanese Patent Application Laid-Open No. 2003-146920, and a method for simply suppressing sublimation of the molybdenum component constituting the catalyst. .

  Molybdenum contained in the catalyst is an essential component, and the reduction of molybdenum from the catalyst surface due to sublimation of molybdenum has a great influence on the reaction activity and reaction selectivity of the catalyst. Also, water vapor is thought to promote the sublimation of molybdenum. Contrary to this finding, the supply of water vapor before starting the supply of the reaction raw material gas creates an atmosphere in which the catalyst is exposed to water vapor, and thus is generally difficult to implement. Here, the concentration of the supplied water vapor cannot be freely set in view of the viewpoint of avoiding the explosion range of the reaction raw material gas. Therefore, we focused on the steam supply time before the start of the reaction source gas supply, which can be shortened by the start-up operation of the reactor.

The time (upper limit value) from the start of the supply of water vapor to the reactor until the start of the supply of the reaction raw material gas is preferably as short as possible. After starting the supply of water vapor so that the water vapor partial pressure in the gas becomes 2.0 kPa or more, it is preferably less than 5 hours (ie, within 4 hours and 59 minutes), more preferably within 4 hours, and less than 2 hours (ie, 1 hour). Within 59 minutes) is particularly preferred.
On the other hand, after starting the supply of water vapor so that the water vapor partial pressure in all the gases supplied to the reactor is 2.0 kPa or more, the time (lower limit value) until the start of the supply of the reaction raw material gas is The reactor used is an industrial device, and it takes a certain amount of time for water vapor to spread evenly, and in order to condition the surface by adsorbing water molecules to the catalyst to prevent excessive reaction. After the start of the supply of water vapor such that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more, preferably 5 minutes or more, more preferably 15 Minutes or more, more preferably 30 minutes or more, and most preferably 1 hour or more.

Further, the production method of the present invention starts up a fixed bed reactor equipped with a catalyst containing molybdenum, produces a reactant for a certain period, shuts down the reactor, and then restarts the reactor. Also, the present invention can be suitably applied to the case where the supply of reaction raw material gas is started after the supply of water vapor is started so that the partial pressure of water vapor in the total gas supplied to the reactor becomes 2.0 kPa or more.
In the catalyst used for the reaction, molybdenum was often lost by sublimation at the reaction site on the surface of the catalyst, and it was found that the start-up operation at the time of use is particularly important.
The time (upper limit value) until the start of the supply of the reaction raw material gas after the start of the supply of the steam so that the partial pressure of water vapor in the total gas supplied to the reactor becomes 2.0 kPa or more is as short as possible. However, according to the study by the inventors, less than 5 hours (that is, 4 hours 59 minutes) after starting the supply of water vapor so that the water vapor partial pressure in the total gas supplied to the reactor is 2.0 kPa or more. Within 4 hours, more preferably within 4 hours, and particularly preferably within 2 hours (ie within 1 hour 59 minutes).
On the other hand, after starting the supply of water vapor so that the water vapor partial pressure in all the gases supplied to the reactor is 2.0 kPa or more, the time (lower limit value) until the start of the supply of the reaction raw material gas is The reactor used is an industrial device, and it takes a certain amount of time for water vapor to spread evenly, and in order to condition the surface by adsorbing water molecules to the catalyst to prevent excessive reaction. After the start of the supply of water vapor such that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more, preferably 5 minutes or more, more preferably 15 Minutes or more, more preferably 30 minutes or more, and most preferably 1 hour or more.
Moreover, the said fixed period specifically refers to about 1 day to 2 years.

The reaction source gas used in the production method of the present invention is at least one reaction source gas selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol, or unsaturated compounds having 3 and 4 carbon atoms. It is at least one reaction raw material gas selected from the group consisting of aliphatic aldehydes.
Examples of the hydrocarbon having 3 carbon atoms include propylene and propane.
Examples of the hydrocarbon having 4 carbon atoms include butenes such as isobutylene and 1-butene, and butanes such as butane and isobutane.
Examples of the unsaturated aliphatic aldehyde having 3 and 4 carbon atoms include acrolein and methacrolein.
In addition, as the unsaturated aliphatic aldehyde having 3 and 4 carbon atoms in the unsaturated aliphatic aldehyde having 3 and 4 carbon atoms, the unsaturated hydrocarbon, and the unsaturated fatty acid having 3 and 4 carbon atoms as the reactant, Acrolein and methacrolein are mentioned. Unsaturated hydrocarbons include unsaturated hydrocarbons having 4 carbon atoms, especially butadiene. Unsaturated fatty acids having 3 and 4 carbon atoms include acrylic acid and methacrylic acid. .

  The reaction raw material gas may have only one type, or a mixture of two or more types. The composition of the reaction source gas is appropriately selected according to the purpose.

In the present invention, when starting up a fixed-bed reactor equipped with a catalyst containing molybdenum, the reactor contains oxygen-containing gas such as air, water vapor, and optionally inert gas such as nitrogen. To supply. Here, the supply timing of the gas inert to the reaction such as water vapor and nitrogen is arbitrary and may be the same as the oxygen-containing gas such as air, or after the start of the supply of the oxygen-containing gas such as air. It does not matter. These supply amounts and compositions are selected from the viewpoint of avoiding the explosion range of the reaction raw material gas. Here, the supply of water vapor means a gas in a state containing water vapor having a concentration higher than that of water vapor usually contained in the air (hereinafter also referred to as water vapor-containing gas, and includes at least one of water vapor, oxygen-containing gas and inert gas). It is a concept including a gas containing.
Then, after the supply of water vapor or water vapor-containing gas is started, the supply of the reaction raw material gas is started. Preferably, the supply of the reaction raw material gas is started in less than 5 hours after the supply of water vapor or water vapor-containing gas is started.
After the supply of the reaction raw material gas is started, the reactor contains a reaction gas mixture containing these reaction raw material gas, oxygen-containing gas, water vapor and, if necessary, a gas inert to the reaction such as nitrogen (hereinafter simply referred to as reaction). The concentration of each gas in the reaction gas mixture may be adjusted. Here, although content with respect to the said reaction gas mixture of the said reaction raw material gas is not specifically limited, It is preferable that it is 5-13 mol% as a total amount of reaction raw material gas. Moreover, the content of molecular oxygen and water vapor contained in the oxygen-containing gas with respect to the reaction gas mixture is 1 to 3 times and 0.1 to 5 times the total amount of the reaction raw material gas, respectively. preferable.
The content of the inert gas with respect to the reaction gas mixture is a value obtained by removing the total amount of reaction raw material gas, the amount of molecular oxygen, and the amount of water vapor from the total amount of the reaction gas mixture.
In many cases, the inert gas is an inert gas obtained by recirculating exhaust gas discharged from the reaction system. Further, in the start-up process, an amount of water vapor that exceeds the amount of water vapor necessary for the reaction is gradually replaced with exhaust gas, and an operation for lowering the water vapor concentration is often performed. Therefore, it can be said that the water vapor concentration is the highest and the influence on the catalyst is large before the supply of the reaction raw material gas is started.

In the production method of the present invention, a catalyst containing molybdenum is used.
In the present invention, examples of the composition of the catalyst include a metal oxide containing molybdenum, tungsten, bismuth, and the like, or a metal oxide containing molybdenum, vanadium, and the like. The metal oxide powder having this composition is formed into a spherical shape, a pellet shape, a saddle shape, or a ring shape, and calcined at a high temperature to be used as a catalyst.
The catalyst may be formed in a known shape, such as a spherical shape having a diameter of 1 to 15 mm (millimeters), or a pellet shape having an equivalent diameter of 1 to 15 mm in a shape other than an ellipse, or a hole in the center of a cylindrical column. A ring-shaped shape having an open outer diameter of 3 to 10 mm, a circular inner diameter of 1 to 3 mm, and a height of 2 to 10 mm is preferably used. A known method can be used for producing these catalysts.

Specifically, the catalyst for oxidizing at least one reaction raw material gas selected from the group consisting of the hydrocarbons having 3 and 4 carbon atoms and tertiary butanol is represented by the following general formula (1). A catalyst comprising a metal oxide is preferably exemplified.
Mo (a) Bi (b) Co (c) Ni (d) Fe (e) X (f) Y (g) Z (h) Q (i) Si (j) O (k) (1) )
In the above formula (1), Mo is molybdenum, Bi is bismuth, Co is cobalt, Ni is nickel, Fe is iron, X is at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium, Y Is at least one element selected from the group consisting of boron, phosphorus, arsenic and tungsten, Z is at least one element selected from the group consisting of magnesium, calcium, zinc, cerium and samarium, Q is a halogen element, and Si is silica , O represents oxygen. A, b, c, d, e, f, g, h, i, j and k are the atomic ratios of Mo, Bi, Co, Ni, Fe, X, Y, Z, Q, Si and O, respectively. When the molybdenum atom (Mo) is 12, 0.5 ≦ b ≦ 7, 0 ≦ c ≦ 10, 0 ≦ d ≦ 1
0, 1 ≦ c + d ≦ 10, 0.05 ≦ e ≦ 3, 0.0005 ≦ f ≦ 3, 0 ≦ g ≦ 3, 0 ≦ h ≦ 1, 0 ≦ i ≦ 0.5, 0 ≦ j ≦ 40 Yes, k is a value determined by the oxidation state of each element.

On the other hand, the catalyst for oxidizing at least one kind of the reaction raw material gas selected from the group consisting of the above-mentioned unsaturated aliphatic aldehydes having 3 and 4 carbon atoms comprises a metal oxide represented by the following general formula (2). A catalyst is preferably exemplified.
Mo (12) V (a) X (b) Cu (c) Y (d) Sb (e) Z (f) Si (g) C (h) O (i) (2)
In the above formula (2), X represents at least one element selected from the group consisting of Nb and W. Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba and Zn. Z represents at least one element selected from the group consisting of Fe, Co, Ni, Bi, and Al. However, Mo, V, Nb, Cu, W, Sb, Mg, Ca, Sr, Ba, Zn, Fe, Co, Ni, Bi, Al, Si, C, and O are element symbols.
a, b, c, d, e, f, g, h, and i represent the atomic ratio of each element, and 0 <a ≦ 12, 0 ≦ b ≦ 12, 0 ≦ with respect to the molybdenum atom (Mo) 12. c ≦ 12, 0 ≦ d ≦ 8, 0 ≦ e ≦ 500, 0 ≦ f ≦ 500, 0 ≦ g ≦ 500, 0 ≦ h ≦ 500, and i is a value of each component except C among the above components. The value is determined by the degree of oxidation.

The fixed bed reactor used in the production method of the present invention will be described.
It does not specifically limit as a fixed bed type reactor used for the manufacturing method of this invention, A well-known multitubular reactor and a plate type reactor are mentioned.

Preferable examples of the multi-tubular reactor include a reactor described in JP-A-2005-336085.
The multi-tubular reactor includes a cylindrical reactor shell having a reaction gas supply port and a reactant discharge port, and a cylindrical reactor shell for introducing or deriving a heat medium into the cylindrical reactor shell. A plurality of annular conduits arranged on the outer periphery, a circulation device for connecting the plurality of annular conduits to each other, a plurality of reaction tubes constrained by a plurality of tube plates of the reactor and containing a catalyst, and the reactor It is a multi-tube reactor having a plurality of baffle plates for changing the direction of the heat medium introduced into the shell in the longitudinal direction of the reaction tube. The reaction tube is filled with a catalyst containing molybdenum.

One embodiment of the multi-tubular reactor will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view for showing one embodiment of a multitubular reactor.
The reaction tubes (1b) and (1c) are fixed to the tube plates (5a) and (5b) in the shell (2) of the multitubular reactor. The raw material supply port that is the inlet of the reaction gas and the reactant discharge port that is the outlet of the reactant are (4a) or (4b). The flow of the reaction gas and the heat medium may be countercurrent or cocurrent, but countercurrent is preferred. Further, the flow direction of the reaction gas may be an upward flow or a downward flow.
In FIG. 1, the flow direction of the heat medium in the reactor shell is indicated by an arrow as an upward flow, and the flow of the reaction gas and the heat medium is designed to be a countercurrent, so (4b ) Is a raw material supply port. An annular conduit (3a) for introducing a heat medium is installed on the outer periphery of the reactor shell. The heating medium pressurized by the circulation pump (7) of the heating medium rises in the reactor shell from the annular conduit (3a), and has a perforated baffle plate (6a) having an opening near the center of the reactor shell. By alternately arranging a plurality of perforated baffle plates (6b) arranged so as to have openings between the outer periphery of the reactor shell, the direction of flow is changed and circulated from the annular conduit (3b). Return to pump. A part of the heat medium that has absorbed the reaction heat is cooled by a heat exchanger (not shown in the figure) from a discharge pipe provided at the top of the circulation pump 7 and reacted again from the heat medium supply line (8a). It is introduced into the vessel. The heat medium temperature is adjusted by controlling the temperature or flow rate of the reflux heat medium introduced from the heat medium supply line (8a) based on the signal fed back from the thermometer (13).
Although the temperature control of the heat medium depends on the performance of the catalyst used, the temperature difference of the heat medium between the heat medium supply line (8a) and the heat medium extraction line (8b) is 1 to 10 ° C, preferably 2 to 6 ° C. It is done to become.
Further, a thermometer (11) is inserted into the reaction tube arranged in the reactor, a signal is transmitted to the outside of the reactor, and the temperature distribution of the catalyst layer in the reactor tube axial direction is recorded. A plurality of thermometers are inserted in the reaction tube, and one thermometer measures temperatures of 5 to 20 points in the tube axis direction.

  FIG. 2 shows a schematic cross-sectional view of a multi-tubular reactor when the reactor shell is divided by an intermediate tube plate (9). In each divided space, a separate heat medium is circulated and controlled at different temperatures. The reaction raw material gas may be introduced from either (4a) or (4b), but in FIG. 2, the flow direction of the heat medium in the reactor shell is indicated by an arrow as an upward flow. The raw material supply port is the flow (4b) in which the flow is opposite to the flow of the heat medium. The reaction raw material gas introduced from the raw material supply port (4b) sequentially reacts in the reaction tube of the reactor.

  The multitubular reactor shown in FIG. 2 has a heat medium having different temperatures in the upper and lower areas (A area and B area in FIG. 2) of the reactor divided by the intermediate tube plate (9). 1) Cases in which the same catalyst is filled as a whole and the reaction is performed by changing the temperature at the reaction gas inlet and outlet of the reaction tube. 2) The catalyst is filled in the reaction gas inlet and the reaction product is rapidly cooled. Therefore, the case where the outlet part is not filled with a catalyst and is filled with an empty cylinder or an inert substance having no reaction activity, 3) The reaction gas inlet part and the outlet part are filled with different catalysts, and the reaction products are rapidly In some cases, the catalyst is not filled for cooling, but is filled with an empty cylinder or an inert substance having no reaction activity.

  For example, at least one reaction raw material gas selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol is introduced into the multitubular reactor shown in FIG. 2 from the raw material supply port (4b). First, at least one reaction raw material gas selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms in the first stage for the first stage reaction (A area of the reaction tube), and further two stages for the second stage reaction From the group consisting of unsaturated fatty acids having 3 and 4 carbons by oxidizing at least one reaction raw material gas selected from the group consisting of the unsaturated aliphatic aldehydes having 3 and 4 carbon atoms in the eyes (B area of the reaction tube) Produces at least one selected. The first stage part (hereinafter also referred to as “front part”) and the second stage part (hereinafter also referred to as “rear part”) of the reaction tube are filled with different catalysts, and are optimally controlled at different temperatures. The reaction takes place under various conditions. It is preferable that an inert substance not involved in the reaction is filled in a portion where the intermediate tube plate is present between the front stage portion and the rear stage portion of the reaction tube. Here, the front stage part and the rear stage part are incorporated in one reactor, but the front stage part is incorporated in the first reactor having the structure shown in FIG. 1 and the rear stage part is different from the first reactor. It is also possible to manufacture the reactant by incorporating it in the second reactor having the structure shown in FIG.

  The inner diameter of the reaction tube provided in the multi-tubular reactor is influenced by the amount of reaction heat and the catalyst particle size in the reaction tube, but is preferably 10 to 50 mm, and more preferably 20 to 30 mm. If the inner diameter of the reaction tube is too small, the amount of catalyst to be filled will decrease, the number of reaction tubes will increase with respect to the required amount of catalyst, and the labor for manufacturing the reactor will increase. Economic efficiency is worsened. On the other hand, if the inner diameter of the reaction tube is too large, the surface area of the reaction tube becomes small relative to the required amount of catalyst, and the heat transfer area for heat removal from the reaction heat is reduced. Further, the length of the reaction tube is not particularly limited.

On the other hand, as a first preferred example of the plate reactor, a reactor described in JP-A No. 2004-167448 can be exemplified.
That is, a plate reactor having a heat medium flow path in which a reaction zone is formed by filling a catalyst in a space between two heat transfer plates, and a heat medium is supplied to the outside of the heat transfer plate. It is done.
The reaction zone of the plate reactor can be divided into a plurality of regions, and the thickness of the catalyst layer filled in each reaction zone can be changed by adjusting the interval between the two heat transfer plates. Is possible. In particular, a structure in which the catalyst layer thickness in each region of the reaction zone increases from the inlet to the outlet of the reaction gas to be supplied is preferable. In addition, the outside of the two heat transfer plates is divided into a plurality of heat medium flow paths, and it is possible to supply heat mediums having different temperatures to the flow paths.
The amount of reaction in a normal reaction is the largest at the inlet portion of the reaction gas, the generation of reaction heat accompanying the reaction is the largest, and decreases in the direction of the outlet of the reaction raw material gas. By adjusting the distance between the two heat transfer plates and changing the thickness of the catalyst layer, the reaction and the heat generated by the reaction can be controlled more precisely, preventing hot spots as the catalyst layer temperature rises and damaging the catalyst Can be prevented.
The direction of the reaction gas supplied to the plate reactor flows along the heat transfer plate, and the heat medium is supplied to the outside of the heat transfer plate. The flow direction of the heat medium is not particularly limited, but an industrial scale reaction apparatus usually needs to accommodate a large amount of catalyst, and a large number of heat transfer plate pairs are installed. A direction perpendicular to the flow is convenient.

FIG. 3 shows a specific example of the first plate reactor.
The thin heat transfer plate (10) that separates the heat medium flow path (15-1, 15-2, and 15-3) from the catalyst layer (12) is formed from the reaction gas inlet (4b) to the reaction gas outlet (4a). In order to change the thickness of the catalyst layer (12) along the flow of reaction gas to Here, the thickness of the catalyst layer is a distance between the plates measured in a direction perpendicular to the flow direction of the reaction gas.
The thickness of the catalyst layer (12) formed between the two heat transfer plates (10) corresponds to each heat medium flow path (15-1, 15-2 and 15-3), respectively. Reaction zones (S1, S2, and S3) are formed. (16) is a heat medium supply port. In the above, there are three reaction zones, but this is an example, and the number of reaction zones is not limited.
Further, the heat transfer plate (10) can be a flat plate, a plate embossed to have irregularities, or a corrugated plate formed in a direction perpendicular to the flow of the reaction gas. In consideration of the heat transfer efficiency between the reaction gas and the heat medium, an uneven plate or corrugated plate shape is preferably used. Here, the thickness of the catalyst layer when embossing or corrugated plate was used for the heat transfer plate (10) was defined by the following equation.
(Formula) [Catalyst layer thickness] = [Catalyst layer volume] / [Heat transfer plate length (width) (length in the direction perpendicular to the paper surface in FIG. 3)] / [Heat transfer plate reaction gas Length in the flow direction]
(Here, [volume of catalyst layer] is 2 by keeping the two heat transfer plates on which the catalyst layer is formed perpendicular to the ground and installing a lid on the bottom (the bottom surface of each reaction zone). When a liquid such as water or a glass bead having a diameter of 1 mm or less is poured into a space sandwiched between one heat transfer plate, the liquid such as water or a glass bead having a diameter of 1 mm or less necessary to fill the space (Volume)

As a second preferred example of the plate reactor, there can be mentioned a reactor described in JP-A No. 2004-202430.
That is, a plurality of heat transfer plates in which a plurality of corrugated plates shaped into an arc, an elliptical arc, or a rectangle face each other and the convex portions of the corrugated plates are joined together to form a plurality of heat medium channels are arranged. And a plate reactor in which corrugated convex portions and concave portions of adjacent heat transfer plates face each other to form a catalyst layer at a predetermined interval.
In the above plate reactor, the thickness of the catalyst layer is changed from the inlet to the outlet of the reaction gas supplied to the catalyst layer by changing the shape of the arc, elliptical arc, or rectangle formed on the corrugated plate. Is possible. The plate reactor can divide the reaction zone into a plurality of regions, and the reaction zone divided into the plurality of regions can correspond to the change in the thickness of the catalyst layer. . Further, a plurality of the divided reaction zones are supplied with a heat medium whose temperature is independently adjusted, and the heat generated by the catalytic gas phase oxidation reaction is removed through the heat transfer plate, so that the temperature in the catalyst layer is reduced. It can be controlled independently.
The direction of the reaction gas supplied to the plate reactor flows along the outside of the heat transfer plate, and the heat medium is supplied to the inside of the heat transfer plate. The flow direction of the heat medium flows in a direction perpendicular to the flow of the reaction gas, that is, a cross flow direction.
In the normal reaction, the reaction amount is the largest at the inlet portion of the reaction gas, the generation of reaction heat accompanying the reaction is the largest, and decreases in the direction of the reaction gas outlet. In order to efficiently remove the reaction heat, the corrugated shape of the corrugated plate used for the heat transfer plate can be changed, and the gap between the two heat transfer plates can be adjusted to change the thickness of the catalyst layer. preferable. By changing the thickness of the catalyst layer, the reaction can be controlled more precisely, and hot spots accompanying the increase in the catalyst layer temperature can be prevented, and damage to the catalyst can be prevented.

FIG. 4 shows a specific example of the second plate reactor.
As shown in FIG. 4, the heat transfer plate (10) has two corrugated plates shaped like a circle, an ellipse, a rectangle, or a polygon facing each other, and the convex portions of the corrugated plates are joined to each other. Thus, a plurality of heat medium flow paths (15-1, 15-2, 15-3) are formed. Further, two adjacent heat transfer plates (10) are shifted from each other by a distance corresponding to half of the heat medium flow path to form a facing gap, and the formed gap is filled with a catalyst, and the catalyst layer (12). Is formed. Further, the two adjacent heat transfer plates (10) include a reaction gas inlet (4b) for introducing the reaction gas into the catalyst layer (12) and a reaction gas outlet (4a) for deriving the reaction gas.
The heat medium flow paths may have different cross-sectional shapes (cross-sectional areas) as shown in FIG. In the case where the width of the heat medium flow path (15-1) is designed to be the largest as shown in FIG. 4, since the interval between the adjacent heat transfer plates (10) is constant, the waves of the adjacent heat transfer plates are The distance (A) (that is, the layer thickness of the catalyst layer (12)) formed so that the plate convex surface portion and the concave surface portion face each other is the narrowest. In FIG. 4, the width of the heat medium flow path gradually decreases from the heat medium flow path (15-2) to (15-3), and the thickness of the catalyst layer (12) corresponding to the heat medium flow path is Increase. Therefore, the catalyst layers (12) corresponding to the heat medium flow paths (15-1, 15-2, and 15-3) have a plurality of reaction zones having different catalyst layer thicknesses and different catalyst layer thicknesses. (S1, S2, and S3) can be formed. Here, the thickness of the catalyst layer means an average value of the interval (A) measured in the direction perpendicular to the flow direction of the reaction gas in each catalyst layer of each reaction zone (S1, S2, and S3). . In this invention, it prescribed | regulated using the calculation formula shown below.
(Formula) [Catalyst layer thickness] = [Catalyst layer volume] ÷ [Heat transfer plate length (width) (length in the direction perpendicular to the paper surface in FIG. 4)] ÷ [Heat transfer plate reaction gas Length in the flow direction]
(Here, [volume of catalyst layer] is 2 by keeping the two heat transfer plates on which the catalyst layer is formed perpendicular to the ground and installing a lid on the bottom (the bottom surface of each reaction zone). When a liquid such as water or a glass bead having a diameter of 1 mm or less is poured into a space sandwiched between one heat transfer plate, the liquid such as water or a glass bead having a diameter of 1 mm or less necessary to fill the space (Volume)
In the above, there are three reaction zones, but this is an example, and the number of reaction zones is not limited.

The structure of the heat transfer plate (10) used in the specific example of the second plate reactor will be described in more detail with reference to FIG. FIG. 5 shows heat transfer in which a plurality of corrugated plates deformed into an arc, an elliptical arc, a rectangle or a polygon are faced to each other, and the convex portions of the corrugated plates are joined together to form a plurality of heat medium flow paths. The plate is shown.
The size of the heat medium flow path and the thickness of the catalyst layer are defined by the wave period (L) and the wave height (H). At this time, the wave period (L) is preferably 10 to 100 mm, and more preferably 20 to 50 mm. On the other hand, the height (H) is preferably 5 to 50 mm, and more preferably 10 to 30 mm.
The two heat transfer plates are parallel to each other and are shifted from each other by a distance (L / 2) corresponding to half of the heat medium flow path to form a facing gap. The gap is filled with a catalyst to form a catalyst layer. .
The thickness of the catalyst layer is adjusted by changing the interval (P) between the two parallel heat transfer plates and the period (L) and height (H) of the heat medium flow path. The interval P between the two heat transfer plates is usually 10 to 50 mm.
In FIG. 5, the shape of the heat transfer plate is drawn as a part of an arc, but the shape may be an elliptical arc, a rectangle, a triangle, or a polygon. The catalyst layer thickness can be accurately controlled by changing the period (L) and the height (H). The catalyst layer thickness is preferably uniform in the length (width) direction (direction perpendicular to the paper surface) of the heat transfer plate.
Further, the thickness of the catalyst layer correlates with the interval (x) shown in FIG. 5, and the interval (x) is usually 0.7 to 0.9 times the thickness of the catalyst layer defined by the above formula. .

The plate thickness of the thin plate of the heat transfer plate (10) of the plate reactor is 2 mm or less, preferably 1 mm or less.
The length of the heat transfer plate (10) in the reaction gas flow direction is usually 2 m (meters) or less, and when it is 2 m or more, the two plates can be joined or combined.
The length in the direction perpendicular to the flow direction of the reaction gas (the depth perpendicular to the paper surface in FIGS. 3 and 4) is not particularly limited, and usually 3 to 15 meters is used. Preferably it is 6 to 10 meters. The heat transfer plates (10) are stacked in the same manner as in the arrangement shown in FIG. 5, and the number of stacked plates is not limited. In practice, it is determined from the amount of catalyst required for the reaction, but it is from several tens to several hundreds.

Although the thickness of the catalyst layer of each said reaction zone is not specifically limited, It is preferable that it is 4-50 mm.
In addition, although the thickness of the catalyst layer in each reaction zone differs depending on the reaction raw material gas load and the catalyst shape (particle size, etc.), in the plate reactor shown in FIG. 3, the reaction zone (S1) The thickness of the catalyst layer is 4-18 mm (more preferably 5-13 mm), and the thickness of the catalyst layer in the reaction zone (S2) following the reaction zone (S1) is 5-23 mm (more preferably 7- The thickness of the catalyst layer in the reaction zone (S3) following the reaction zone (S2) is preferably 8 to 27 mm (more preferably 10 to 22 mm).
On the other hand, in the plate reactor shown in FIG. 4, the thickness of the catalyst layer in the reaction zone (S1) is 5 to 20 mm (more preferably 7 to 15 mm), and the reaction zone (S1) following the reaction zone (S1) The thickness of the catalyst layer in S2) is 7 to 25 mm (more preferably 10 to 20 mm), and the thickness of the catalyst layer in the reaction zone (S3) following the reaction zone (S2) is 12 to 30 mm (more preferably). 15 to 25 mm) can be preferably exemplified.
In addition, it is preferable that the thickness of the catalyst layers of the plurality of reaction zones is sequentially increased as it is positioned in the direction from the inlet to the outlet of the reaction gas.

Although the details of the thickness of the catalyst layer vary depending on the amount of reaction, it may be changed continuously from the inlet to the outlet of the catalyst layer (12) or may be changed stepwise. Rather, considering the unevenness of the reaction activity when producing the catalyst, the degree of freedom may be secured by changing the thickness of the catalyst layer stepwise.
In addition, the number of divisions of the reaction zone is preferably 2 to 5, and the thickness of the catalyst layer in each reaction zone is preferably increased from the reaction gas inlet to the outlet.
Further, the length of the reaction direction of the reaction gas in the catalyst layer in each reaction zone is determined in consideration of the conversion rate of the reaction raw material gas and the like. For example, in the case where the reaction zone is divided into three, The catalyst layer having a reaction zone (S1) portion of 10% to 55%, a reaction zone (S2) portion of 20% to 65%, and a reaction zone (S3) portion of 25% to 70% of the total catalyst layer length. It is preferable to apply the length. Further, the catalyst layer length in the reaction zone (S3) is preferably changed depending on the achievement of the conversion rate of the reaction raw material gas.

In the above reaction, in order to keep the conversion rate of the reaction raw material gas and the like optimally, the temperature of the heat medium can be adjusted. The heat medium is preferably supplied to each of the plurality of reaction zones at an optimum temperature. At this time, the direction in which the heat medium flows is preferably orthogonal to the flow direction of the reaction gas.
The temperature difference between the inlet temperature and the outlet temperature of the heat medium is preferably 0.5 to 10 ° C, more preferably 2 to 5 ° C.
In the case of the plate reactor shown in FIG. 4, in each of the heat medium flow paths (15-1, 15-2, 15-3), the flow rate of the heat medium, temperature, and It is also possible to change the flow direction. In one reaction zone, the heat medium having the same temperature may flow independently in the same direction or may flow in the counterflow direction for each of one to a plurality of flow paths. It is also possible to supply the heat medium supplied to and discharged from the heat medium flow path in a certain reaction zone to the heat medium flow path in the same or another reaction zone.

In each of the above reactors, the temperature of the heat medium supplied to the heat medium flow path is such that the reaction raw material gas is at least one of the reaction raw material gases selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol. When it is a seed, it is preferably 250 to 450 ° C. When the reaction raw material gas is propylene, the temperature of the heat medium supplied to the plurality of reaction zones is preferably 250 to 400 ° C.
On the other hand, when the reaction raw material gas is at least one reaction raw material gas selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms, the temperature is preferably 200 to 350 ° C. When the reaction raw material gas is acrolein, the temperature of the heat medium supplied to the plurality of reaction zones is preferably 200 to 350 ° C.
Moreover, in the manufacturing method of this invention, it is preferable to keep the conversion rate of reaction raw material gas optimal by adjusting the temperature of the said heat medium. The conversion rate of the reaction raw material gas at the reaction gas outlet of each reactor is preferably 90% or more, more preferably 95% or more, and particularly preferably 97% or more.

A suitable example of the heat medium is a molten salt (nighter). Nighter is particularly excellent in thermal stability among heat media used for temperature control of chemical reaction. In particular, it has the best thermal stability at a high temperature of 350 to 550 ° C.
As a compound used for the nighter, there are sodium nitrate, sodium nitrite, and potassium nitrate, and these can be used alone or in admixture of two or more.

EXAMPLES Hereinafter, although this invention is demonstrated in more detail using an Example, this invention is not limited to these at all.
The calculation method of the conversion rate of reaction raw material gases (propylene and acrolein), the selectivity of acrylic acid, and the yield of acrylic acid used in this example is described below.
<1> Propylene Conversion [%] = 100 − [(Propylene Volume Flow at Reactor (B) Exit) / (Propylene Volume Flow Supplyed to Reactor (A)) × 100
<2> Conversion rate of acrolein [%] = 100 − [(volume flow rate of acrolein at the outlet of the reactor (B)) / (volume flow rate of propylene supplied to the reactor (A)) × 100
<3> Yield of acrylic acid [%] = (volume flow rate of acrylic acid at the outlet of the reactor (B)) / (volume flow rate of propylene supplied to the reactor (A)) × 100
<4> Acrylic acid selectivity [%] = (acrylic acid yield) / (propylene conversion) / (acrolein conversion) × 100
Further, the unit “NL” used in the present example means a volume (L) in terms of a standard state (temperature 0 ° C., pressure 101.325 kPa).

  In the production of acrylic acid by catalytic vapor phase oxidation of propylene with molecular oxygen, Mo (12) Bi (5) Co (3) Ni (2) Fe ( A metal oxide powder having a composition of 0.4) Na (0.4) B (0.2) K (0.08) Si (24) O (x) was prepared and molded to obtain an outer diameter of 5 mmφ, A ring-shaped catalyst (A) having an inner diameter of 2 mmφ and a height of 3 mm was obtained. Furthermore, as a catalyst for the subsequent stage for converting acrolein to acrylic acid, the composition of Mo (12) V (2.4) Ni (15) Nb (1) Cu (1) Sb (34) Si (7) O (x) A metal oxide powder was prepared, and this powder was molded to obtain a catalyst (B) having the same shape as the propylene oxidation catalyst. Here, (x) of O (x) is a value determined by the oxidation state of each metal oxide.

<Example 1>
In this example, two multitubular reactors having the same structure as that shown in FIG. 1 were used. Specifically, a reaction tube made of stainless steel having a reaction tube length of 3,500 mm and an inner diameter of 25 mm filled with 1 liter (L) of the above catalyst (A) per reaction tube is referred to as reactor (A). did. A reactor (B) was prepared by filling a stainless steel reaction tube having a reaction tube length of 3,500 mm and an inner diameter of 25 mm with 1 liter (L) of the catalyst (B) per reaction tube. The reaction tube for monitoring the temperature of the catalyst layer was provided with a multi-point thermocouple having an outer diameter of 4 mm and filled with a catalyst in the same manner as the other reaction tubes.
First, the heat medium temperature of the reactor (A) was maintained at 300 ° C., and the heat medium temperature of the reactor (B) was maintained at 240 ° C. Then, from the top of the reactor (A), air 550 NL / hr having a dew point lower than −15 ° C. and nitrogen 310 NL / hr having a dew point lower than −15 ° C. are supplied per reaction tube, and then steam 70 NL / hr is supplied. Supplied and operated at a gauge pressure of 8 kPa. At this time, the water vapor concentration in the total gas supplied to the reactor was 7.5% by volume, and the water vapor partial pressure in the total gas supplied to the reactor was 8.0 kPa. Next, propylene supply was started 20 minutes after the start of supply of water vapor, and after 1 hour, the supply amount of propylene was set to 70 NL / hr, and the operation was performed at a gauge pressure of 75 kPa. Moreover, the obtained reaction gas, air 150NL / hr, nitrogen 50NL / hr were mixed, supplied from the upper part of the reactor (B), and operated at a gauge pressure of 45 kPa.
The temperature of the heat medium supplied to each reactor (315) was 315 ° C. so that the conversion rate of propylene was 98% and the conversion rate of acrolein was 99%. The operation was performed while adjusting the temperature of the heat medium supplied to the reactor (B) to 270 ° C.
The selectivity for acrylic acid, measured one week after the start of operation, was 88.1%.
One week after the start of operation, the operation was temporarily stopped (shut down), and the reactor was restarted. The re-startup procedure is as follows.
First, air 550 NL / hr having a dew point lower than −15 ° C. and nitrogen 310 NL / hr having a dew point lower than −15 ° C. are supplied from the upper part of the reactor (A), then steam 70 NL / hr is supplied, and the gauge pressure is 8 kPa. Drove in. At this time, the water vapor concentration in the total gas supplied to the reactor was 7.5% by volume, and the water vapor partial pressure in the total gas supplied to the reactor was 8.0 kPa. Propylene supply was started 20 minutes after the start of the supply of water vapor, and after 1 hour, the supply amount of propylene was 70 NL / hr, and the operation was performed at a gauge pressure of 75 kPa. In addition, the reaction gas obtained was mixed with 150 NL / hr of air having a dew point lower than minus 15 ° C. and 50 NL / hr of nitrogen having a dew point lower than minus 15 ° C., supplied from the upper part of the reactor (B), and operated at a gauge pressure of 45 kPa. Went.
The temperature of the heat medium supplied to the reactor (A) was 317 ° C. so that the conversion rate of propylene was 98% and the conversion rate of acrolein was 99%. The operation was performed while adjusting the temperature of the heat medium supplied to the reactor (B) to 273 ° C. As a result, the selectivity of acrylic acid, measured after 1 week from the restart of operation, was 88.9%.

<Example 2>
As a result of operating under the same conditions using the same reactor as in Example 1, the selectivity for acrylic acid, measured after 1 week from the start of the operation, was 88.2%. Next, as in Example 1, one week after the start of operation, the operation was temporarily stopped (shut down), and the reactor was restarted. The restarting procedure and operating conditions were the same as those in Example 1, except that the propylene supply was started 1 hour and 50 minutes after the start of the steam supply. As a result, the selectivity of acrylic acid, measured after 1 week from the restart of operation, was 88.9%.

<Example 3>
As a result of operating under the same conditions using the same reactor as in Example 1, the selectivity for acrylic acid, measured after 1 week from the start of the operation, was 88.1%. Next, as in Example 1, one week after the start of operation, the operation was temporarily stopped (shut down), and the reactor was restarted. The restarting procedure and operating conditions were the same as those in Example 1 except that propylene supply was started 4 hours after the start of steam supply. As a result, the selectivity of acrylic acid measured after one week from the restart of operation was 88.5%.

<Example 4>
As a result of operating under the same conditions using the same reactor as in Example 1, the selectivity for acrylic acid, measured after 1 week from the start of the operation, was 88.0%.
Next, as in Example 1, one week after the start of operation, the operation was temporarily stopped (shut down), and the reactor was restarted. The restarting procedure and operating conditions were the same as those in Example 1, except that propylene supply was started 5 hours after the start of supplying steam. As a result, the selectivity of acrylic acid, measured after 1 week from restarting the operation, was 87.0%.

<Comparative Example 1>
As a result of operating under the same conditions using the same reactor as in Example 1, the selectivity for acrylic acid, measured after 1 week from the start of the operation, was 88.1%.
Next, as in Example 1, one week after the start of operation, the operation was temporarily stopped (shut down), and the reactor was restarted. In the restart procedure and operating conditions, from the top of the reactor (A), air 550 NL / hr obtained by directly compressing air in the atmosphere with a compressor, and nitrogen 380 NL / hr with a dew point lower than minus 15 ° C. After the supply, it was operated at a gauge pressure of 8 kPa. Although no additional water vapor was supplied, since there was water vapor in the air, the partial pressure of water vapor in the total gas supplied to the reactor was 1.7 kPa. Propylene supply is started 20 minutes after the start of nitrogen supply, and the supply of water vapor in the same amount as propylene is started following the supply of propylene, so that the total supply amount of the supplied water vapor and nitrogen becomes 380 NL / hr. In addition, restarting was performed in the same procedure and operating conditions as in Example 1 except that the amount of nitrogen was reduced. As a result, the selectivity of acrylic acid measured after one week from the restart of operation was 86.9%.

<Example 5>
The same catalyst as in Example 1 was used, and a plate type reactor having the structure shown in FIG. 4 was used. Two thin corrugated stainless steel plates (thickness 1 mm) were joined to form a heat medium flow path for adjusting the reaction temperature. Table 1 shows the period (L), height (H), and wave number of the waveform shape shown in FIG.
A pair of the corrugated heat transfer plates was filled with the catalyst (A) in the former reactor in Table 1 and the catalyst (B) in the latter reactor to form a catalyst layer. As shown in Table 1, the catalyst layers of the upstream reactor and the downstream reactor are changed to the reaction zone (S1), reaction zone (S2), and reaction zone (S3) from the upstream in the flow direction of the reaction gas as shown in Table 1. Divided. A pair of corrugated heat transfer plates were installed in parallel as shown in FIG. 4, and the interval (P shown in FIG. 5) was adjusted to 26 mm. The width of the heat transfer plate was 114 mm.

The amount of catalyst shown in Table 1 is a result of volume measurement measured by pouring water from the upper part with a plate attached to the lowermost part of the catalyst layer with each reactor vertical. The amount of the catalyst was used for calculating the amount of reaction raw material.
The temperature was adjusted using NeoSK-OIL (registered trademark) 1400 manufactured by Soken Technics Co., Ltd. as the heat medium, and then supplied to reaction zone (S1) to reaction zone (S3). The supply amount of the heat medium was such that the flow rate of the heat medium was 0.7 m or more per second.
First, air 3340 NL / hr with a dew point lower than minus 15 ° C. and nitrogen 970 NL / hr with a dew point lower than minus 15 ° C. are supplied from the upper part of the former reactor, and then steam 389 NL / hr is supplied and operated at a gauge pressure of 7 kPa. did. At this time, the water vapor concentration in the total gas supplied to the reactor was 8.3% by volume, and the partial pressure of water vapor in the total gas supplied to the reactor was 9.0 kPa. After confirming that the flow rates of air, nitrogen, and water vapor are stable, the supply of propylene is started one hour after the start of the supply of water vapor, and the supply amount of propylene is gradually increased. After an hour, operation was performed at a gauge pressure of 69 kPa with a propylene supply amount of 433 NL / hr. The obtained reaction gas was mixed with air 834 NL / hr with a dew point lower than minus 15 ° C. and nitrogen 357 NL / hr with a dew point lower than minus 15 ° C., supplied from the upper part of the subsequent reactor, and operated at a gauge pressure of 43 kPa. It was.
The temperature of the heat medium supplied to each reaction zone (S1), (S2), and (S3) was 339 ° C., 332 ° C., and 332 ° C., respectively.
10 hours after starting the supply of propylene, the gas at the outlet of the previous reactor was analyzed by gas chromatography. As a result, the conversion of propylene was 97.0%, and the total selectivity of acrylic acid and acrolein was 92.4%.
Twelve hours after the start of propylene supply, the supply of propylene raw material was temporarily stopped while the supply of air, nitrogen and water vapor was continued. The supply of propylene was started 36 hours after the start of the supply of water vapor, the supply amount was gradually increased, and the propylene flow rate was set to 433 NL / hr 8 hours after the restart of the supply of propylene.
10 hours after the resumption of propylene supply, the pre-reactor outlet gas was analyzed by gas chromatography. As a result, the conversion of propylene was 97.1% and the total selectivity of acrylic acid and acrolein was 92.6%.
At this time, the temperature of the heat medium supplied to each reaction zone (S1), (S2), and (S3) was 344 ° C, 332 ° C, and 332 ° C, respectively.

<Comparative example 2>
In Example 5, the operation was started under the same conditions except that the supply of water vapor was not performed before the supply of propylene, and the supply of water vapor and propylene was started simultaneously.
The temperature of the heat medium supplied to each reaction zone (S1), (S2), and (S3) was 339 ° C., 332 ° C., and 332 ° C., respectively.
10 hours after the start of the supply of propylene, the gas at the outlet of the previous reactor was analyzed by gas chromatography. The conversion of propylene was 97.5% and the total selectivity of acrylic acid and acrolein was 91.9%.
Twelve hours after the start of propylene supply, the supply of propylene raw material was temporarily stopped while the supply of air, nitrogen and water vapor was continued. The supply of propylene was started 36 hours after the start of the supply of water vapor, the supply amount was gradually increased, and the propylene flow rate was set to 433 NL / hr 8 hours after the restart of the supply of propylene.
10 hours after the resumption of propylene supply, the pre-reactor outlet gas was analyzed by gas chromatography. As a result, the conversion of propylene was 97.6% and the total selectivity of acrylic acid and acrolein was 91.8%.
At this time, the temperature of the heat medium supplied to each reaction zone (S1), (S2), and (S3) was 344 ° C, 332 ° C, and 332 ° C, respectively.

1b, 1c Reaction tube 2 Reactor (shell)
3a, 3b Annular conduit 3a ', 3b' Annular conduit 4a Reactant discharge port or reaction gas outlet 4b Raw material supply port or reaction gas inlet 5a, 5b Tube plate 6a, 6b Perforated baffle plate 6a ', 6b' Perforated baffle plate 7 Circulation pumps 8a and 8a 'Heat medium supply lines 8b and 8b' Heat medium extraction line 9 Intermediate tube plate 10 Heat transfer plates 11 and 13 Thermometer 12 Catalyst layer 15-1 Heat medium flow path 15-2 Heat medium flow path 15 -3 Heat medium flow path 16 Heat medium supply port P Interval between the pair of heat transfer plates L Wave period H Wave height x Interval

Claims (8)

Using a fixed bed reactor equipped with a catalyst containing molybdenum, at least one reaction raw material gas selected from the group consisting of hydrocarbons having 3 and 4 carbon atoms and tertiary butanol, or 3 carbon atoms And at least one reaction raw material gas selected from the group consisting of unsaturated aliphatic aldehydes of 4 is subjected to catalytic gas phase oxidation using an oxygen-containing gas in the presence of water vapor, to produce unsaturated carbon atoms of 3 and 4 In a production method for producing at least one reactant selected from the group consisting of aliphatic aldehydes, unsaturated hydrocarbons, and unsaturated fatty acids having 3 and 4 carbon atoms,
When starting up the reactor, after starting the supply of water vapor so that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or higher, the supply of the reaction raw material gas is started. A process for producing at least one reactant selected from the group consisting of unsaturated aliphatic aldehydes having 3 and 4 carbon atoms, unsaturated hydrocarbons, and unsaturated fatty acids having 3 and 4 carbon atoms.   When starting up the reactor, the supply of the reaction raw material gas is started in less than 5 hours after starting the supply of water vapor so that the partial pressure of water vapor in the total gas supplied to the reactor is 2.0 kPa or more. The manufacturing method according to claim 1, wherein:   The startup is performed when the reactor is started up, the reactant is manufactured for a certain period, the reactor is shut down, and then the reactor is restarted. 3. The production method according to 1 or 2. A catalyst for catalytic gas phase oxidation of at least one reaction raw material gas selected from the group consisting of the hydrocarbons having 3 and 4 carbon atoms and tertiary butanol using an oxygen-containing gas in the presence of water vapor. The manufacturing method according to claim 1, comprising a metal oxide represented by the following general formula (1).
Mo (a) Bi (b) Co (c) Ni (d) Fe (e) X (f) Y (g) Z (h) Q (i) Si (j) O (k) (1) )
(In the above formula (1), Mo is molybdenum, Bi is bismuth, Co is cobalt, Ni is nickel, Fe is iron, X is at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium, Y is at least one element selected from the group consisting of boron, phosphorus, arsenic and tungsten, Z is at least one element selected from the group consisting of magnesium, calcium, zinc, cerium and samarium, Q is a halogen element, and Si is Silica, O represents oxygen, and a, b, c, d, e, f, g, h, i, j, and k are Mo, Bi, Co, Ni, Fe, X, Y, Z, Q represents the atomic ratio of Si and O, and when the molybdenum atom (Mo) is 12, 0.5 ≦ b ≦ 7, 0 ≦ c ≦ 10, 0 ≦ d ≦ 10, 1 ≦ c + d ≦ 10, 0. 5 ≦ e ≦ 3, 0.0005 ≦ f ≦ 3, 0 ≦ g ≦ 3, 0 ≦ h ≦ 1, 0 ≦ i ≦ 0.5, 0 ≦ j ≦ 40, and k depends on the oxidation state of each element. (The value is determined.) A catalyst for catalytic vapor phase oxidation of at least one reaction raw material gas selected from the group consisting of the unsaturated aliphatic aldehydes having 3 and 4 carbon atoms using an oxygen-containing gas in the presence of water vapor is: It consists of a metal oxide represented by General formula (2), The manufacturing method of any one of Claim 1 to 3 characterized by the above-mentioned.
Mo (12) V (a) X (b) Cu (c) Y (d) Sb (e) Z (f) Si (g) C (h) O (i) (2)
(In the above formula (2), X represents at least one element selected from the group consisting of Nb and W. Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba and Zn. Z represents at least one element selected from the group consisting of Fe, Co, Ni, Bi, and Al, provided that Mo, V, Nb, Cu, W, Sb, Mg, Ca, Sr, Ba, Zn, Fe, Co, Ni, Bi, Al, Si, C and O are element symbols.
Further, a, b, c, d, e, f, g, h and i represent atomic ratios of the respective elements, and 0 <a ≦ 12, 0 ≦ b ≦ 12 with respect to the molybdenum atom (Mo) 12, 0 ≦ c ≦ 12, 0 ≦ d ≦ 8, 0 ≦ e ≦ 500, 0 ≦ f ≦ 500, 0 ≦ g ≦ 500, 0 ≦ h ≦ 500, and i is each of the above components except C The value is determined by the degree of oxidation of the component. )   The hydrocarbon having 3 carbon atoms is propylene or propane, the hydrocarbon having 4 carbon atoms is isobutylene, 1-butene, isobutane, or butane, and the unsaturated aliphatic aldehyde having 3 or 4 carbon atoms. Is acrolein or methacrolein, the unsaturated hydrocarbon is butadiene, and the unsaturated fatty acid having 3 and 4 carbon atoms is acrylic acid or methacrylic acid. The production method according to item.   The manufacturing method according to any one of claims 1 to 6, wherein the fixed bed reactor is a multi-tubular reactor including a reaction tube, and the inner diameter of the reaction tube is 10 to 50 mm.   The fixed bed reactor is a plate reactor having a catalyst layer formed between heat transfer plates, and the plate reactor is divided into a plurality of reaction zones having different catalyst layer thicknesses. The production method according to claim 1, wherein the plurality of reaction zones are plate reactors in which a heat medium whose temperature is independently adjusted is supplied.

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