JP4824871B2 - Method for producing acrolein and acrylic acid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing acrolein and acrylic acid by gas phase catalytic oxidation of propylene with molecular oxygen in the presence of a solid oxidation catalyst using a fixed bed tubular reactor.
[0002]
[Prior art]
Numerous proposals have been made regarding catalysts used in the production of acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene. These proposals mainly relate to the elements constituting the catalyst and their proportions.
[0003]
Since the gas phase catalytic oxidation is an exothermic reaction, heat storage occurs in the catalyst layer. The local high temperature zone resulting from the heat storage is called a hot spot, and if the temperature of this part is too high, an excessive oxidation reaction occurs and the yield of the target product is lowered. For this reason, in the industrial implementation of the oxidation reaction, temperature control of the hot spot is a serious problem, and particularly when the propylene concentration in the raw material gas is increased in order to increase productivity, the temperature of the hot spot tends to increase. Therefore, the current situation is that the reaction conditions are largely restricted.
[0004]
Therefore, it is very important to suppress the temperature of the hot spot part in industrially producing acrolein and acrylic acid at a high yield. In particular, when a molybdenum-containing solid oxidation catalyst is used, it is important to prevent the occurrence of hot spots because the molybdenum component tends to sublime.
[0005]
As a method for suppressing the temperature of the hot spot part, several proposals have been made so far. For example, in Japanese Patent Application Laid-Open No. Sho 55-113730, a plurality of catalysts having different activities prepared by varying the catalyst composition are packed so that the activity becomes higher from the raw material gas inlet side toward the outlet side. A method of circulating a source gas containing propylene and oxygen in a catalyst layer is disclosed. Japanese Patent Laid-Open No. 8-92147 discloses that when a propylene is vapor-phase oxidized to acrolein using a multi-tube fixed bed reactor equipped with a heat medium bath, the temperature of the heat medium bath is changed to the inlet portion of the reactor. And a method of controlling the flow of the heating medium so as to increase by 2 to 10 ° C. between the outlet portion and the outlet portion.
[0006]
In these methods, the reaction rate per unit volume on the raw material gas inlet side in the catalyst layer in the reactor is lowered, thereby suppressing the reaction heat generation amount per unit volume, and as a result, trying to lower the temperature of the hot spot part. It is a method to do.
[0007]
[Problems to be solved by the invention]
However, these methods alone have a problem that the temperature of the hot spot is not sufficiently suppressed, and the yields of acrolein and acrylic acid are low.
[0008]
The present invention provides a method for producing acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene with molecular oxygen in the presence of a solid oxidation catalyst in a fixed bed tubular reactor to sufficiently suppress the temperature of the hot spot part. An object of the present invention is to provide a method for producing acrolein and acrylic acid in high yield.
[0009]
[Means for Solving the Problems]
The present invention provides a raw material gas containing 4 to 9% by volume of propylene, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor in the catalyst layer of a fixed bed tubular reactor packed with a solid oxidation catalyst. In the method for producing acrolein and acrylic acid to be circulated, before the raw material gas is circulated, 250% of the catalyst layer containing oxygen, nitrogen and water vapor and propylene is circulated in a flow of 250% by volume. The temperature is raised to a range of ˜400 ° C., and then a gas containing 1 to 3.8% by volume of propylene, 7 to 16% by volume of oxygen, and 5 to 50% by volume of water vapor is circulated at 250 to 400 ° C. for 1 hour or more. A process for producing acrolein and acrylic acid.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the reaction for synthesizing acrolein and acrylic acid is carried out using a fixed bed tubular reactor. The tubular reactor is not particularly limited, but industrially, a multitubular reactor provided with several thousand to several tens of thousands of reaction tubes having an inner diameter of 10 to 40 mm is preferable. The fixed bed tubular reactor is preferably equipped with a heat medium bath. The heat medium is not particularly limited, and examples thereof include a salt melt containing potassium nitrate and sodium nitrite.
[0011]
In the present invention, the solid oxidation catalyst to be used is not particularly limited as long as it is a solid catalyst for this oxidation reaction, and conventionally known composite oxides containing molybdenum and the like can be used. A composite oxide represented by
_{Mo a Bi b Fe c A d} X e Y f Z g Si h O i (1)
In the formula (1), Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, A is nickel and / or cobalt, X is magnesium, zinc, chromium, manganese, tin, strontium , Barium, copper, silver and lead, at least one element selected from the group consisting of Y, phosphorus, boron, sulfur, tellurium, aluminum, gallium, germanium, indium, lanthanum, cerium, niobium, tantalum, titanium, zirconium , At least one element selected from the group consisting of tungsten and antimony, Z represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium. However, a, b, c, d, e, f, g, h, and i represent the atomic ratio of each element, and when a = 12, 0.01 ≦ b ≦ 5, 0.01 ≦ c ≦ 5, 1 ≦ d ≦ 12, 0 ≦ e ≦ 10, 0 ≦ f ≦ 10, 0.001 ≦ g ≦ 3, 0 ≦ h ≦ 20, and i is oxygen necessary to satisfy the valence of each element Is the atomic ratio. Particularly preferable atomic ratios of the respective elements are 0.1 ≦ b ≦ 3, 0.1 ≦ c ≦ 4, 2 ≦ d ≦ 10, and 0.005 ≦ g ≦ 2 when a = 12.
[0012]
The method for preparing the catalyst used in the present invention is not particularly limited, and various well-known methods can be used as long as there is no significant uneven distribution of components.
[0013]
The raw materials used for the preparation of the catalyst are not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides and the like of each element can be used in combination. For example, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, etc. can be used as the molybdenum raw material.
[0014]
The catalyst used in the present invention may be carrier-free, but a supported catalyst supported on an inert carrier such as silica, alumina, silica-alumina, silicon carbide, or a catalyst diluted with these can also be used.
[0015]
In the present invention, the catalyst layer refers to a space portion containing at least the catalyst in the reaction tube of the fixed bed tubular reactor. That is, not only the space filled with only the catalyst but also the space where the catalyst is diluted with an inert carrier or the like is used as the catalyst layer. However, the space portion where nothing is filled at both ends of the reaction tube or the space portion where only the inert carrier is filled is not included in the catalyst layer because the catalyst is substantially not included.
[0016]
A reaction (hereinafter simply referred to as an oxidation reaction) for synthesizing acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene with molecular oxygen in the presence of a solid oxidation catalyst using a fixed bed tubular reactor is usually 250-. It is carried out at a reaction temperature in the range of 400 ° C. However, a raw material gas containing 4 to 9% by volume of propylene, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor from the beginning of the reaction in the catalyst layer maintained at a reaction temperature of about 250 to 400 ° C. When the raw material gas is simply circulated, a hot spot having a maximum temperature is generated near the raw material gas inlet of the catalyst layer.
[0017]
As a result of intensive studies to solve this problem, the inventor of the present application has circulated a gas containing oxygen, nitrogen and water vapor and propylene in an amount of 0 to 0.5% by volume before circulating the raw material gas. The temperature is raised to a range of 250 to 400 ° C., and then a gas containing 1 to 3.8% by volume of propylene, 7 to 16% by volume of oxygen, and 5 to 50% by volume of water vapor is circulated at 250 to 400 ° C. for 1 hour or more. As a result, when the oxidation reaction is carried out at a reaction temperature of 250 to 400 ° C. using normal reaction conditions, that is, the raw material gas, the temperature of the hot spot part can be sufficiently suppressed, resulting in high yield of acrolein and acrylic acid. It was found that it can be manufactured at a rate.
[0018]
The temperature before the temperature is raised to the range of 250 to 400 ° C, that is, the temperature at which the temperature rises is not particularly limited, but is preferably in the range of 10 to 240 ° C. Further, the rate of temperature rise is not particularly limited, but is preferably 10 to 500 ° C./hour, particularly preferably 20 to 400 ° C./hour.
[0019]
A gas to be circulated when the temperature is raised to a range of 250 to 400 ° C. is a gas containing oxygen, nitrogen and water vapor and propylene in an amount of 0 to 0.5% by volume. The concentrations of oxygen, nitrogen and water vapor in this gas are not particularly limited, but oxygen is preferably 1 to 21% by volume, nitrogen is 29 to 98.5% by volume, and water vapor is preferably 0.5 to 50% by volume. Propylene is 0 to 0.5% by volume, more preferably 0 to 0.3% by volume, and particularly preferably 0 to 0.1% by volume. When a gas with a propylene concentration exceeding 0.5% by volume is passed in a state where the catalyst layer temperature is less than 250 ° C., a compound having a relatively high boiling point produced on the catalyst may poison the active site of the catalyst. is there. This gas may contain a gas other than oxygen, nitrogen, water vapor, and propylene. Examples of such a gas include inert gases such as carbon dioxide, lower saturated aldehydes, and ketones. However, when an organic compound such as a lower saturated aldehyde is included, the sum of the concentrations of propylene and other organic compounds is preferably 0.5% by volume or less. The gas flow rate at the time of temperature rise is not particularly limited, but a flow rate such that the space velocity is 100 to 2000 hr ⁻¹ is preferable. The pressure in the reactor at this time is usually from atmospheric pressure to several atmospheres.
[0020]
The gas to be circulated after the temperature rise is a gas containing 1 to 3.8% by volume of propylene, 7 to 16% by volume of oxygen, and 5 to 50% by volume of water vapor. The concentration of propylene is preferably 1 to 3% by volume, and particularly preferably 1 to 2.5% by volume. The oxygen concentration is preferably 7.5 to 14% by volume, particularly preferably 8 to 12% by volume. The water vapor concentration is preferably 2 to 40% by volume, particularly preferably 4 to 30% by volume. The temperature at which this gas is circulated is 250 to 400 ° C. Moreover, the time which distribute | circulates this gas is 1 hour or more, 1.5 to 100 hours are preferable, and 2 to 50 hours are especially preferable. This gas may contain a gas other than oxygen, water vapor, and propylene. Examples of such a gas include nitrogen, carbon dioxide, lower saturated aldehyde, and ketone. The flow rate of the gas to be circulated after the temperature rise is not particularly limited, but a flow rate at which the space velocity is 100 to 3000 hr ⁻¹ is preferable. The pressure in the reactor at this time is usually from atmospheric pressure to several atmospheres. When this gas flows, hot spots having a low maximum temperature are generated in a wide portion of the catalyst layer.
[0021]
Thereafter, when an oxidation reaction is performed at a reaction temperature of 250 to 400 ° C. using normal reaction conditions, that is, a raw material gas containing 4 to 9% by volume of propylene, the maximum temperature of the hot spot is suppressed. As a result, sequential oxidation in the hot spot portion is suppressed, and acrolein and acrylic acid can be produced with high yield. The flow rate of the source gas is not particularly limited, but a flow rate such that the space velocity is 300 to 3000 hr ⁻¹ is preferable, and a flow rate such that 500 to 2000 hr ⁻¹ is particularly preferable. The reaction temperature of the oxidation reaction is preferably 250 to 400 ° C, particularly preferably 270 to 360 ° C. The reaction pressure can be from normal pressure to several atmospheres.
[0022]
In the practice of the present invention, it is economically advantageous to use air as the source gas, the gas to be circulated at the time of temperature rise, and the oxygen source of the gas to be circulated after the temperature rise.
[0023]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. In addition, "part" in an Example and a comparative example means a mass part. The catalyst composition was determined from the raw material charge of the catalyst component. As a heat medium for the reactor, a salt melt composed of 50% by mass of potassium nitrate and 50% by mass of sodium nitrite was used. A hot spot was detected by ΔT of the catalyst layer (temperature of the catalyst layer−temperature of the heat medium bath).
[0024]
The temperature in the catalyst layer was measured by a thermocouple inserted in a protective tube installed at the center of the cross section perpendicular to the tube axis direction of the reaction tube. The inside of the protective tube is isolated from the reaction system, and the temperature measuring position can be changed by adjusting the length of the thermocouple to be inserted.
[0025]
The analysis of the raw material gas and the reaction product gas was performed by gas chromatography. The reaction rate of propylene, the selectivity of the generated acrolein and acrylic acid, and the yield of acrolein and acrylic acid are respectively defined as follows.
Propylene reaction rate (%) = (B / A) × 100
Acrolein selectivity (%) = (C / B) × 100
Acrylic acid selectivity (%) = (D / B) × 100
Yield (%) of acrolein and acrylic acid = {(C + D) / A} × 100
Here, A is the number of moles of propylene supplied, B is the number of moles of propylene reacted, C is the number of moles of acrolein produced, and D is the number of moles of acrylic acid produced.
[0026]
[Example 1]
To 1000 parts of water, 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, 1.4 parts of potassium nitrate and 212.7 parts of 20% by mass silica sol were added and stirred with heating (liquid A). Separately, 50 parts of 60% by mass nitric acid was added to 850 parts of water to make it uniform, and then 103.0 parts of bismuth nitrate were added and dissolved. To this, 114.4 parts of ferric nitrate, 274.7 parts of cobalt nitrate, 34.3 parts of nickel nitrate, 7.0 parts of zinc nitrate and 30.3 parts of magnesium nitrate were sequentially added and dissolved (Liquid B). After liquid B was added to liquid A to form a slurry, 10.3 parts of antimony trioxide was added and stirred with heating to evaporate most of the water. The obtained cake-like product was dried at 120 ° C. and then baked at 500 ° C. for 4 hours. After adding 2 parts of graphite to 100 parts of the fired product obtained, a catalyst 1 was obtained by molding into a ring shape having an outer diameter of 4 mm, an inner diameter of 2 mm, and a length of 4 mm by a tableting machine. The composition of elements other than oxygen in the catalyst 1 is Mo ₁₂ W _0.1 Bi _0.9 Fe _1.2 Co ₄ Ni _0.5 Zn _0.1 Mg _0.5 Sb _0.3 K _0.06 Si ₃ there were.
[0027]
The heat medium bath temperature of a steel fixed-bed tube reactor with an inner diameter of 25.4 mm equipped with a heat medium bath is set to 180 ° C., and 620 mL of catalyst 1 and 130 mL of alumina spheres with an outer diameter of 5 mm are mixed on the raw material gas inlet side. Then, 750 mL of catalyst 1 was charged on the outlet side. At this time, the length of the catalyst layer was 3005 mm.
[0028]
The heat medium bath temperature was raised to 310 ° C. at 50 ° C./hour while a gas consisting of 9 vol% oxygen, 10 vol% water vapor and 81 vol% nitrogen was passed through the catalyst layer at a space velocity of 240 hr ⁻¹ .
[0029]
Next, a gas consisting of 2% by volume of propylene, 8% by volume of oxygen, 15% by volume of water vapor and 75% by volume of nitrogen (circulation gas after heating) was passed for 3 hours at a space velocity of 1000 hr ⁻¹ with the heat medium bath temperature of 310 ° C. I let you.
[0030]
Subsequently, a raw material gas composed of 5% by volume of propylene, 12% by volume of oxygen, 10% by volume of water vapor and 73% by volume of nitrogen was maintained at a heat medium bath temperature of 310 ° C., a reaction temperature (heat medium bath temperature) of 340 ° C., and a space velocity of 1000 hr. ^-1 . When the temperature of the catalyst layer at this time was measured, a hot spot having the maximum temperature was observed at a position 500 mm from the end on the raw material gas inlet side, and ΔT at this maximum temperature was 29 ° C. The propylene reaction rate was 98.5%, the acrolein selectivity was 88.3%, the acrylic acid selectivity was 5.8%, and the yield of acrolein and acrylic acid was 92.7%.
[0031]
[Example 2]
The oxidation reaction was carried out in the same manner as in Example 1 except that the composition of the flow gas after the temperature increase was changed to 2.6% by volume of propylene, 8% by volume of oxygen, 15% by volume of water vapor and 74.4% by volume of nitrogen. As a result, a hot spot having a maximum temperature was observed at a position of 470 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 31 ° C. The propylene reaction rate was 98.6%, the acrolein selectivity was 88.1%, the acrylic acid selectivity was 5.8%, and the yield of acrolein and acrylic acid was 92.6%.
[0032]
[Example 3]
The oxidation reaction was performed in the same manner as in Example 1 except that the flow time of the flow gas after temperature increase was changed to 1.5 hours. As a result, a hot spot having a maximum temperature was observed at a position of 470 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 31 ° C. The propylene reaction rate was 98.6%, the acrolein selectivity was 88.1%, the acrylic acid selectivity was 5.8%, and the yield of acrolein and acrylic acid was 92.6%.
[0033]
[Comparative Example 1]
After raising the temperature, the temperature was raised to the heat medium bath temperature of 310 ° C. without circulating the flow gas, and then the oxidation reaction was performed in the same manner as in Example 1 except that the raw material gas was immediately passed. As a result, a hot spot having the maximum temperature was observed at a position 400 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 41 ° C. The propylene reaction rate was 98.9%, the acrolein selectivity was 86.5%, the acrylic acid selectivity was 5.0%, and the yield of acrolein and acrylic acid was 90.5%.
[0034]
[Comparative Example 2]
The oxidation reaction was carried out in the same manner as in Example 1 except that the flow time of the flow gas after temperature increase was changed to 10 minutes. As a result, a hot spot having the maximum temperature was observed at a position 400 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 40 ° C. The propylene reaction rate was 98.7%, the acrolein selectivity was 86.7%, the acrylic acid selectivity was 5.1%, and the yield of acrolein and acrylic acid was 90.6%.
[0035]
[Comparative Example 3]
The oxidation reaction was carried out in the same manner as in Example 1 except that the composition of the flowing gas after the temperature increase was changed to 4.5% by volume of propylene, 12% by volume of oxygen, 10% by volume of water vapor, and 73.5% by volume of nitrogen. As a result, a hot spot having a maximum temperature was observed at a position 400 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 41 ° C. The propylene reaction rate was 98.9%, the acrolein selectivity was 86.5%, the acrylic acid selectivity was 5.0%, and the yield of acrolein and acrylic acid was 90.5%.
[0036]
[Comparative Example 4]
The oxidation reaction was performed in the same manner as in Example 1 except that the composition of the flow gas after the temperature increase was changed to 0.6 volume% propylene, 8 volume% oxygen, 15 volume% water vapor, and 76.4 volume% nitrogen. As a result, a hot spot having the maximum temperature was observed at a position 400 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at this maximum temperature was 40 ° C. The propylene reaction rate was 98.7%, the acrolein selectivity was 86.7%, the acrylic acid selectivity was 5.1%, and the yield of acrolein and acrylic acid was 90.6%.
[0037]
[Comparative Example 5]
Except that the composition of the gas to be circulated when the temperature of the heating medium bath was raised to 310 ° C. was changed to 2% by volume of propylene, 8% by volume of oxygen, 15% by volume of water vapor and 75% by volume of nitrogen, the same as in Example 1. An oxidation reaction was performed. As a result, a hot spot having a maximum temperature was observed at a position 550 mm from the end of the catalyst layer on the raw material gas inlet side, and ΔT at the maximum temperature was 20 ° C. The propylene reaction rate was 94.7%, the acrolein selectivity was 88.0%, the acrylic acid selectivity was 5.6%, and the yields of acrolein and acrylic acid were 88.6%. According to this result, the ΔT of the hot spot was reduced as compared with Example 1, but the reaction rate of propylene was also reduced, so it is considered that the catalyst was poisoned during the temperature increase.
[0038]
[Example 4]
After adding 500 parts of ammonium paramolybdate, 12.3 parts of ammonium paratungstate, and 1.4 parts of potassium nitrate to 1000 parts of water and heating and stirring, 4.1 parts of 85 mass% phosphoric acid was dissolved in 100 parts of water. The mixture was added and further heated and stirred (C solution). Separately, 50 parts of 60% by mass nitric acid was added to 850 parts of water to make it uniform, and then 114.5 parts of bismuth nitrate were added and dissolved. To this, 143.0 parts of ferric nitrate, 309.0 parts of cobalt nitrate, 7.0 parts of zinc nitrate, 3.2 parts of silver nitrate and 6.1 parts of magnesium nitrate were sequentially added and dissolved (solution D). After liquid D was added to liquid C to form a slurry, the mixture was heated and stirred to evaporate most of the water. The obtained cake-like substance was dried at 130 ° C., then fired at 300 ° C. for 1 hour in an air atmosphere and pulverized. 2 parts of graphite was added to and mixed with 100 parts of the obtained pulverized product, and formed into a ring shape having an outer diameter of 4 mm, an inner diameter of 2 mm, and a length of 4 mm by a tableting machine. The tableting product was calcined at 500 ° C. for 6 hours in an air atmosphere to obtain Catalyst 2. The composition of the catalyst 2 is Mo ₁₂ W _0.2 Bi ₁ Fe _1.5 P _0.15 Ag _0.08 Co _4.5 Zn _0.1 Mg _0.1 K _{0.06 in} an atomic ratio excluding oxygen. Met.
[0039]
The heat medium bath temperature of a steel fixed-bed tube reactor with an inner diameter of 25.4 mm equipped with a heat medium bath is set to 180 ° C., and 620 mL of catalyst 2 and 130 mL of alumina spheres with an outer diameter of 5 mm are mixed on the raw material gas inlet side. Then, 750 mL of catalyst 2 was charged on the outlet side. At this time, the length of the catalyst layer was 3005 mm.
[0040]
The heat medium bath temperature was raised to 310 ° C. at 50 ° C./hour while a gas consisting of 9 vol% oxygen, 10 vol% water vapor and 81 vol% nitrogen was passed through the catalyst layer at a space velocity of 240 hr ⁻¹ .
[0041]
Subsequently, a gas composed of 2% by volume of propylene, 8% by volume of oxygen, 15% by volume of water vapor and 75% by volume of nitrogen was passed for 3 hours at a space velocity of 1000 hr ⁻¹ with the heat medium bath temperature of 310 ° C.
[0042]
Subsequently, the raw material gas composed of 5% by volume of propylene, 12% by volume of oxygen, 10% by volume of water vapor and 73% by volume of nitrogen was maintained at a reaction temperature (heat medium bath temperature) of 310 ° C., and a space velocity of 1000 hr. ^-1 . When the temperature of the catalyst layer at this time was measured, a hot spot having a maximum temperature was observed at a position 550 mm from the end on the raw material gas inlet side, and ΔT at this maximum temperature was 32 ° C. The propylene reaction rate was 99.0%, the acrolein selectivity was 89.0%, the acrylic acid selectivity was 6.2%, and the yields of acrolein and acrylic acid were 94.2%.
[0043]
[Comparative Example 6]
After raising the temperature, the temperature was raised to the heat medium bath temperature of 310 ° C. without circulating the circulating gas, and then the oxidation reaction was performed in the same manner as in Example 4 except that the raw material gas was immediately passed. As a result, a hot spot having a maximum temperature was observed at a position 450 mm from the end on the raw material gas inlet side of the catalyst layer, and ΔT at this maximum temperature was 44 ° C. The propylene reaction rate was 99.4%, the acrolein selectivity was 86.5%, the acrylic acid selectivity was 5.9%, and the yield of acrolein and acrylic acid was 91.8%.
[0044]
【The invention's effect】
According to the present invention, in a method for producing acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene with molecular oxygen in the presence of a solid oxidation catalyst in a fixed bed tubular reactor, the temperature of the hot spot is sufficiently increased. And acrolein and acrylic acid can be produced in high yield.
[0045]
Moreover, a yield improves further by using the complex oxide represented by the said Formula (1) as a solid oxidation catalyst.

Claims (2)

Acrolein in which a raw material gas containing 4 to 9% by volume of propylene, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor is circulated in the catalyst layer of the fixed bed tubular reactor filled with the solid oxidation catalyst; In the method for producing acrylic acid, before circulating the raw material gas, the catalyst layer contains oxygen, nitrogen, and water vapor, and propylene is 0 to 0.5% by volume while circulating a gas of 250 to 400 ° C. The temperature is raised to a range, and then a gas containing 1 to 3.8% by volume of propylene, 7 to 16% by volume of oxygen, and 5 to 50% by volume of water vapor is circulated at 250 to 400 ° C. for 1 hour or longer. A process for producing acrolein and acrylic acid. The method for producing acrolein and acrylic acid according to claim 1, wherein the solid oxidation catalyst is a composite oxide represented by the following formula (1).
_{Mo a Bi b Fe c A d} X e Y f Z g Si h O i (1)
(Wherein Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, A is nickel and / or cobalt, X is magnesium, zinc, chromium, manganese, tin, strontium, barium, respectively) At least one element selected from the group consisting of copper, silver and lead, Y is phosphorus, boron, sulfur, tellurium, aluminum, gallium, germanium, indium, lanthanum, cerium, niobium, tantalum, titanium, zirconium, tungsten And at least one element selected from the group consisting of antimony, Z represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium, provided that a, b, c, d , E, f, g, h and i represent the atomic ratio of each element, and a = 2, 0.01 ≦ b ≦ 5, 0.01 ≦ c ≦ 5, 1 ≦ d ≦ 12, 0 ≦ e ≦ 10, 0 ≦ f ≦ 10, 0.001 ≦ g ≦ 3, 0 ≦ h ≦ And i is the atomic ratio of oxygen necessary to satisfy the valence of each element.)