Process for producing unsaturated aldehydes or unsaturated carboxylic acids

Abstract

The production method of the unsaturated aldehyde or unsaturated carboxylic acid of the present invention is characterized in that it is a method of producing the corresponding unsaturated aldehyde or unsaturated carboxylic acid by partial oxidation of an olefin using a fixed bed multi-tube type reactor, and the production parameter T satisfies the following formula (I): T ≤ 20.5 (I).

Description

Technical Field

[0001] This invention relates to a method for producing corresponding unsaturated aldehydes or unsaturated carboxylic acids by gas-phase catalytic oxidation of olefins using molecular oxygen or a gas containing molecular oxygen. Background Technology

[0002] In industry, methods for producing corresponding unsaturated aldehydes and / or unsaturated carboxylic acids using propylene, isobutylene, tert-butanol, etc., as raw materials are widely implemented (e.g., Patent Document 1). Patent Document 1 relates to catalysts for improving the yield of unsaturated aldehydes and / or unsaturated carboxylic acids as target products, and as described below, discloses not only several techniques relating to the catalyst itself, but also several techniques relating to catalyst packing methods.

[0003] For example, Patent Document 2 discloses a technique for adjusting the activity of a catalyst by changing the occupied volume of the catalyst molding body and the sintering temperature of the catalyst. This involves filling a catalyst containing a specific inactive support with the catalyst in a manner that increases in activity from the inlet side to the outlet side in order to suppress the formation of localized high-temperature portions (hot spots) in the catalyst layer. Furthermore, Patent Document 3 discloses a technique for obtaining the target product with high yield and high activity by filling the catalyst in a manner that changes the composition ratio of the active components from the inlet side to the outlet side. Moreover, Patent Document 4 discloses a technique for suppressing hot spots and obtaining unsaturated aldehydes with high yield by specifying the filling length ratio of each layer of a two-layered catalyst. Patent Document 5 discloses a technique for obtaining high yield by suppressing hot spot temperature by specifying the reaction conditions and catalyst in a manner that controls the temperature change of hot spots at each reaction bath temperature.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 7209901

[0007] Patent Document 2: Japanese Patent Application Publication No. 2001-328951

[0008] Patent Document 3: Japanese Patent No. 6694884

[0009] Patent Document 4: Japanese Patent No. 6912153

[0010] Patent Document 5: Japanese Patent No. 6199972 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] However, for the stable operation of the equipment, it can be said that the technology related to the above-disclosed filling method is not yet sufficient. This is because, in the case of a filling method in which the yield of the target product changes sensitively to the change of the control factor in the operation of the equipment, namely the change of the reaction bath temperature, the stable operation of the equipment becomes difficult for the three reasons listed in (1) to (3) below. That is, (1) it is known that the above-disclosed method for producing unsaturated aldehydes and / or unsaturated carboxylic acids is an exothermic reaction, so a multi-tube flow reactor is used in actual equipment. However, the reaction bath temperature in each reaction tube is not necessarily uniform in space, and there is a problem of temperature deviation in each reaction tube. In this case, since the heat release of each reaction tube is different, the hot spot temperature (peak temperature) is also different, the conversion rate of the raw materials is also different, and as a result, the yield of the target product is also different for each reaction tube, and the target product cannot be obtained stably. (2) The reaction bath temperature is controlled by measuring the temperature of the heat medium in the reactor with a thermocouple and heating the heat medium with a heater, but the feedback of the temperature control of the heater is not always perfect. For example, fluctuations may occur due to poor feedback, or poor feedback may occur due to unexpected interference and / or component malfunctions. The reaction bath temperature may not remain constant and may change. As a result, the yield of the target product also changes sensitively, and the target product cannot be obtained stably over time. (3) As an indicator of operation in actual equipment, methods such as directly measuring the yield of the target product and the conversion rate of raw materials in the equipment using analytical equipment such as gas chromatographs can be listed. When the yield of the target product and the conversion rate of raw materials are not within the expected range, the equipment operator makes a fine adjustment to the reaction bath temperature. Here, when the yield of the target product changes sensitively with respect to the change in reaction bath temperature, the equipment operator has to carefully make a fine adjustment to the reaction bath temperature, which unnecessarily burdens the reproducibility confirmation and decision-making of the above analysis.

[0013] To overcome the problems mentioned in (1) to (3) above, a catalyst packing method that exhibits a higher yield of the target product over a wider reaction bath temperature range compared to conventional methods is sought, but such a method has not yet been disclosed. In particular, in methods for producing corresponding unsaturated aldehydes or unsaturated carboxylic acids by gas-phase catalytic oxidation of olefins using molecular oxygen or a gas containing molecular oxygen, when the target product is an unsaturated carboxylic acid, a catalyst packing method that exhibits a higher yield of the target product over a wider reaction bath temperature range compared to conventional methods has not yet been disclosed. Therefore, the inventors conducted in-depth research and found that by designing a packing method in a way that satisfies a specific numerical range for a parameter T that integrates the temperature sensitivity parameter of the catalyst, the dilution rate, the packing length ratio, and the spatial velocity of the feedstock, the target product yield is exhibited for a longer and more stable time over a wider reaction bath temperature range compared to conventional methods, thus completing the present invention.

[0014] Solution for solving the problem

[0015] The inventors conducted in-depth research on these aforementioned current situations and problems, and their findings focused on the following: In methods for producing corresponding unsaturated aldehydes or unsaturated carboxylic acids by partial oxidation of olefins using a fixed-bed multi-tube reactor, when the reaction is carried out with a catalyst pack having two or more layers, the catalyst is packed in a way that expands the stable reaction bath temperature range (hereinafter referred to as the operating window) for the combined yield of unsaturated aldehydes and unsaturated carboxylic acids, especially the combined yield of acrolein and acrylic acid (effective yield). It was discovered that by adjusting the feed load as a reaction condition and setting the slope of the feed conversion rate relative to the reaction bath temperature of each catalyst layer (hereinafter referred to as temperature sensitivity), the packing length ratio, and the dilution rate to optimal values, the operating window can be expanded (i.e., a high effective yield can be stably achieved over a wider reaction bath temperature range), thereby increasing the effective yield itself and enabling stable operation at a higher yield.

[0016] That is, the present invention relates to the following 1) to 8). 1)

[0018] A method for producing an unsaturated aldehyde or unsaturated carboxylic acid, characterized in that it is a method for producing the corresponding unsaturated aldehyde or unsaturated carboxylic acid by partially oxidizing an olefin using a fixed-bed multi-tube reactor, wherein the production parameter T satisfies the following formula (I).

[0019] T≤20.5 (I)

[0020] in,

[0021] T is calculated from the average filling parameter Savg and the space velocity SVo of the feed material according to equation (IV).

[0022] T(%·hr / ℃)=Savg(% / ℃)÷SVo( / hr)×10000 (IV)

[0023] Savg calculated the value based on Equation (III) and the arithmetic mean of the filling parameters Si of all catalyst packing layers.

[0024] Savg(% / ℃)=(S1(% / ℃)+…+Sn(% / ℃))÷n(III)

[0025] Si is calculated according to Equation (II) and from the temperature sensitivity parameter CBi of the catalyst in the i-th layer, the dilution rate di, and the filling length ratio Li.

[0026] Si (% / ℃)=CBi (% / ℃)×di (%)÷100×Li (II)

[0027] CBi is a parameter related to the temperature sensitivity of the catalyst in the i-th layer, which is the ratio of the change in raw material conversion rate to the reaction bath temperature. Additionally, n is the total number of catalyst layers in the reaction tube. The subscript i is a natural number from 1 to n. The catalyst layer does not include an inert layer intentionally filled only with inactive substances. 2)

[0029] The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to 1) above is characterized in that the production parameter T satisfies the following formula (V).

[0030] 9.5 ≤ T ≤ 16.5 (V) 3)

[0032] The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to 1) or 2) above is characterized in that the average packing parameter Savg satisfies the following formula (VI).

[0033] 0.090 ≤ Savg ≤ 0.30 (VI) 4)

[0035] The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to any one of 1) to 3) above is characterized in that the catalytic active component contained in the catalyst layer on the most inlet side of the raw material gas for the reaction has the composition represented by the following formula (1-1).

[0036] Mo a1 Bi b1 Ni c1 Co d1 Fe e1 X f1 Cs g1 Z h1 O i1 (1-1)

[0037] In formula (1-1), Mo, Bi, Ni, Co, Fe, and Cs respectively represent molybdenum, bismuth, nickel, cobalt, iron, and cesium, X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium, Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, Cs, and X, a1, b1, c1, d1, e1, f1, g1, h1, and i1 respectively represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, Cs, Z, and oxygen. When a1 = 12, it satisfies 0 < b1 ≤ 7.0, 0 ≤ c1 ≤ 10, 0 < d1 ≤ 10, 0 < c1 + d1 ≤ 20, 0 < e1 ≤ 5.0, 0 ≤ f1 ≤ 2.0, 0 < g1 ≤ 3.0, 0 ≤ h1 ≤ 5.0, and i1 is a value determined by the oxidation state of each element. 5)

[0039] The method for producing an unsaturated aldehyde or an unsaturated carboxylic acid according to any one of 1) to 4) above, wherein the catalytic active component contained in the catalyst layer on the most outlet side of the raw material gas for the reaction has a composition represented by the following formula (1-2).

[0040] Mo a2 Bi b2 Ni c2 Co d2 Fe e2 X f2 K g2 Z h2 O i2 (1-2)

[0041] In the formula (1-2), Mo, Bi, Ni, Co, Fe, and K respectively represent molybdenum, bismuth, nickel, cobalt, iron, and potassium, X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium, Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, K, and X, a2, b2, c2, d2, e2, f2, g2, h2, and i2 respectively represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, K, Z, and oxygen. When a2 = 12, 0 < b2 ≤ 7.0, 0 ≤ c2 ≤ 10, 0 < d2 ≤ 10, 0 < c2 + d2 ≤ 20, 0 < e2 ≤ 5.0, 0 ≤ f2 ≤ 2.0, 0 ≤ g2 ≤ 3.0, 0 ≤ h2 ≤ 5.0, and i2 is a value determined by the oxidation states of the respective elements. 6)

[0043] The method for producing an unsaturated aldehyde or an unsaturated carboxylic acid according to any one of 1) to 5) above, wherein the reaction bath temperature is set to 310 °C or higher and 390 °C or lower to operate the equipment. 7)

[0045] The method for producing an unsaturated aldehyde or an unsaturated carboxylic acid according to any one of 1) to 6) above, wherein, with respect to the raw material gas for the reaction, the volume ratio of oxygen to olefin (oxygen / olefin) is 1.0 or higher and 1.9 or lower. 8)

[0047] The method for producing an unsaturated aldehyde or an unsaturated carboxylic acid according to any one of 1) to 7) above, wherein, relative to the gas flow direction of the reaction tube, n catalyst layers (n is 2 or more) are provided.

[0048] When the sum of the filling lengths of the catalyst layers from the first layer to the (n-1)th layer, counted from the reactant gas inlet side, is set as L, and when the filling length of the catalyst layer of the nth layer, counted from the reactant gas inlet side, is set as Ln, L / Ln is greater than 0.1 and less than 1.0.

[0049] The effects of the invention

[0050] According to the present invention, when using olefins or alcohols that can produce olefins through intramolecular dehydration reactions as raw materials to manufacture the corresponding unsaturated aldehydes and unsaturated carboxylic acids, the target products can be obtained in high yield over a wide range of reaction bath temperatures in industrial equipment. Detailed Implementation

[0051] The method for manufacturing unsaturated carboxylic acids of the present invention is characterized in that the manufacturing parameter T satisfies the following formula (I).

[0052] [Formula 1]

[0053] T≤20.5 (I)

[0054] The lower limit of the manufacturing parameter T can be 0, and is preferably 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, and 11.0. The upper limit of the manufacturing parameter T is more preferably 19.0, 18.5, 18.0, 17.5, 17.0, 16.5, 16.0, 15.5, 15.0, 14.5, and 14.3. That is, the manufacturing parameter T is preferably 0 or higher and 20.5 or lower, more preferably 0.5 or higher and 20.5 or lower, more preferably 1.0 or higher and 20.5 or lower, more preferably 1.5 or higher and 20.5 or lower, more preferably 2.0 or higher and 20.5 or lower, more preferably 2.5 or higher and 20.5 or lower, more preferably 3.0 or higher and 20.5 or lower, more preferably 3.5 or higher and 20.5 or lower, more preferably 4.0 or higher and 20.5 or lower, more preferably 4.5 or higher and 20.5 or lower, more preferably 5.0 or higher and 20.5 or lower, more preferably 5.5 or higher. Furthermore, the value is 20.5 or less, more preferably 6.0 or more and 19.0 or less, more preferably 6.5 or more and 18.5 or less, more preferably 7.0 or more and 18.0 or less, more preferably 7.5 or more and 17.5 or less, more preferably 8.0 or more and 17.0 or less, more preferably 8.5 or more and 16.5 or less, more preferably 9.0 or more and 16.0 or less, more preferably 9.5 or more and 15.5 or less, more preferably 10.0 or more and 15.0 or less, more preferably 10.5 or more and 14.5 or less, and the most preferred range is 11.0 or more and 14.3 or less.

[0055] Until now, from the viewpoint of improving yield and ensuring safe operation of equipment, there have been insights into specifying the rate of change of hot spot temperature relative to reaction bath temperature (Patent Document 5, etc.), but there have been no insights into catalyst design and packing design that can stably achieve high effective yields over a wide reaction temperature range. This invention is the first to clarify such insights. By packing the catalyst in a manner that satisfies the conditions of this invention, the operating window can be expanded, achieving higher yields and safer, more stable equipment operation. Furthermore, by suppressing runaway reactions, thermal stress on the catalyst is prevented, and a longer lifespan is expected. In more detail, due to minute changes in reaction bath temperature and differences in reaction bath temperature between multiple reaction tubes, the hot spot changes sensitively on the catalyst at the outlet side where the activity is highest, thereby preventing thermal runaway and associated reaction tube breakage and explosion. With a wide operating window, the ability to stably maintain a high effective yield at a lower reaction bath temperature solves the aforementioned problems, which is an advantage. On the other hand, depending on the equipment conditions and limitations, increasing the reaction bath temperature to some extent can increase the relative ratio of acrylic acid to acrolein. This can reduce the load on the subsequent catalyst in the partial oxidation reaction of acrolein to acrylic acid, which is sometimes preferred. In other words, as another technical advantage of the present invention, a filling method can be provided that stably achieves high acrylic acid yields over a wide range of reaction bath temperatures, taking into account the load on the subsequent catalyst.

[0056] The method for calculating the parameter T of the present invention is described below.

[0057] [Calculation of CBi]

[0058] The temperature sensitivity parameter CBi of the catalyst of the present invention is defined as the ratio of the feed conversion rate (x) to the reaction bath temperature (BT) of the catalyst in the i-th layer within a temperature range of 340°C to 360°C. For convenience, the catalyst layers closest to the inlet are numbered as first layer, second layer…, and the corresponding CBi is named CB1, CB2… (in the present invention, other parameters are also defined similarly). The total number of catalyst layers is defined as n. More specifically, CBi is defined as follows: When the catalyst in the i-th layer is filled in a differential system reactor, the feed gas conversion rate x (340°C) (in %) obtained at a reaction bath temperature (hereinafter sometimes referred to as BT) of 340°C and the feed conversion rate x (360°C) (in %) obtained at BT of 360°C are plotted, and the slope of the straight line connecting these points is defined as CBi. That is, CBi is expressed by the following formula.

[0059] CBi(% / ℃)=(x(360℃)(%)-x(340℃))(%) / 20(℃)

[0060] It should be noted that, for convenience, in this invention, the temperature sensitivity parameter of the catalyst calculated during the stage before the numbering of the filled layer is determined will be simply referred to as the CB of the catalyst. Furthermore, the aforementioned feed gas conversion rate x is calculated in this invention using the following method: 4g of catalyst, diluted with an inactive substance to prevent hot spots, is filled into a reaction tube with an inner diameter of 28.4mm. The molar ratio of propylene:oxygen:nitrogen:water = 1:1.7:6.4:3.0 is set, and the space velocity (GHSV) of propylene is set to 400hr. -1 The reaction was carried out at reaction bath temperatures of 340℃ and 360℃. The conversion rate x of the feed gas was calculated using the following formula using a corrected gas chromatograph.

[0061] The following is a calculation formula when the feed gas is propylene. The number of moles of propylene after the reaction is obtained by subtracting the number of moles of propylene remaining after the reaction from the number of moles of propylene supplied.

[0062] Propylene conversion rate x (mol%) = (moles of propylene that reacted / moles of propylene supplied) × 100

[0063] [Savg's calculation]

[0064] Next, the method for calculating the average filling parameter Savg of the present invention is shown below. First, when the catalyst is diluted with an inactive support in each layer, the dilution rate di is set as follows. That is, di is the mass percentage (in mass%) of the catalyst molding in the i-th catalyst layer, and in the undiluted catalyst layer, di is 100. Next, the filling length ratio Li is set. The filling length ratio Li is the ratio of the filling length of the i-th catalyst layer to the filling length of all catalyst layers (excluding the inert layer). For example, for a two-layer catalyst, when the filling length on the inlet side is 20 cm and the filling length on the outlet side is 80 cm, L1 (inlet side) is 0.20. It should be noted that in the case of a single layer, Li is 1.00. The parameter Si of the present invention in the i-th catalyst layer is calculated from the above CBi, di, and Li according to the following formula (II).

[0065] [Formula II]

[0066] Si (% / ℃) = CBi (% / ℃) × di (%) ÷ 100 × Li Formula (II)

[0067] Savg is calculated by taking the arithmetic mean of the parameters Si of each layer (first layer: S1, second layer: S2, etc.) according to the following formula (III). Savg is a filling parameter determined by the type of catalyst and the filling container. In the case of filling a single catalyst layer, Savg is S1.

[0068] [Formula III]

[0069] Savg(% / ℃)=(S1(% / ℃)+…+Sn(% / ℃))÷n(III)

[0070] It should be noted that the number of catalyst layers n is preferably 2 to 5 layers, more preferably 2 to 4 layers, particularly preferably 2 to 3 layers, and most preferably 3 layers.

[0071] [Calculation of T]

[0072] Finally, the manufacturing parameter T is calculated according to the following formula (IV) and from Savg and the spatial velocity SVo of the raw material.

[0073] [Form IV]

[0074] T(%·hr / ℃)=Savg(% / ℃)÷SVo( / hr)×10000 (IV)

[0075] It should be noted that the lower limit of Savg is preferably 0.090, 0.100, 0.150, 0.170, 0.190, 0.200, and 0.220, with a particularly preferred value of 0.240. Similarly, the upper limit of Savg is preferably 0.300, 0.290, 0.280, and 0.275, with a particularly preferred value of 0.270. That is, Savg is preferably 0.090 or higher and 0.300 or lower, more preferably 0.100 or higher and 0.300 or lower, more preferably 0.150 or higher and 0.300 or lower, more preferably 0.170 or higher and 0.300 or lower, more preferably 0.190 or higher and 0.290 or lower, more preferably 0.200 or higher and 0.280 or lower, more preferably 0.220 or higher and 0.275 or lower, and most preferably 0.240 or higher and 0.270 or lower.

[0076] [Calculation of A, A1, A2]

[0077] The operating window of the present invention is defined more specifically below. The reaction bath temperature at which the combined yield of unsaturated aldehydes and unsaturated carboxylic acids (hereinafter referred to as the effective yield) reaches the highest value is defined as A (°C), and the reaction bath temperatures at which the yield is 1.0% lower than the highest value are defined as A1 (°C) and A2 (°C). Furthermore, A is higher than A1, and A2 is higher than A; therefore, (A2-A1) is defined as the narrow operating window of the present invention. (A2-A1) is preferably 23°C or higher. Here, (A2-A1) is the range of reaction bath temperatures at which the effective yield is stable (the operating window of the present invention), and a larger (A2-A1) is preferred, as it allows for the acquisition of unsaturated aldehydes and unsaturated carboxylic acids at a wider range of reaction bath temperatures. It should be noted that A1 and A2 do not need to be calculated based on the measured relationship between the effective yield and BT; they can also be calculated by interpolation or extrapolation of a series of data on the yield of unsaturated aldehydes and unsaturated carboxylic acids measured by changing BT (in this case, at least three points of measured data should be used to calculate the extrapolated value using a linear approximation based on the least squares method). Furthermore, in the measured data with varying BT values, if there are two or more measurement points where the yield reaches its highest level, then in this invention, the measurement point with the higher selectivity is set as A. The reason for the decrease in effective yield near A1 is that the reaction rate of the raw materials decreases, and the reason for the decrease in effective yield near A2 is that decomposition products such as carbon dioxide and acetaldehyde are generated, represented by the successive oxidation reactions of unsaturated aldehydes and unsaturated carboxylic acids.

[0078] [About catalysts]

[0079] The catalyst used in this invention is preferably a catalyst having the composition shown in the following formula (1).

[0080] [Formula 1]

[0081] Mo a Bi b Ni c Co d Fe e X f Y g Z h O i (1)

[0082] In the above formula (1), Mo, Bi, Ni, Co, and Fe represent molybdenum, bismuth, nickel, cobalt, and iron respectively, X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium, Y represents at least one element selected from sodium, potassium, cesium, rubidium, and thallium, Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, X, and Y, a, b, c, d, e, f, g, h, and i represent the atomic numbers of molybdenum, bismuth, nickel, cobalt, iron, X, Y, Z, and oxygen respectively. When a = 12, 0 < b ≤ 7.0, 0 ≤ c ≤ 10, 0 < d ≤ 10, 0 < c + d ≤ 20, 0 < e ≤ 5.0, 0 ≤ f ≤ 2.0, 0 ≤ g ≤ 3.0, 0 ≤ h ≤ 5.0 are satisfied, and i is a value determined by the oxidation states of the respective elements.

[0083] In the above formula (1), when a = 12, the preferred ranges of b to h are as follows.

[0084] As the lower limit of b, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70 are preferably in turn, and as the upper limit, 6.0, 5.0, 4.0, 3.0, 2.0, 1.8, 1.5, 1.2, 1.0 are preferably in turn. That is, b is preferably 0.10 or more and 6.0 or less, more preferably 0.10 or more and 5.0 or less, more preferably 0.10 or more and 4.0 or less, more preferably 0.20 or more and 3.0 or less, more preferably 0.30 or more and 2.0 or less, more preferably 0.40 or more and 1.8 or less, more preferably 0.50 or more and 1.5 or less, more preferably 0.60 or more and 1.2 or less, and the most preferred range is 0.70 or more and 1.0 or less.

[0085] As the lower limit of c, 0.20, 0.50, 0.80, 1.0, 1.2, 1.5, 1.6, 1.7 are preferably in turn, and as the upper limit, 8.0, 7.0, 6.0, 5.0, 4.0, 3.5, 3.4, 3.3 are preferably in turn. That is, c is preferably 0.20 or more and 8.0 or less, more preferably 0.50 or more and 7.0 or less, more preferably 0.80 or more and 6.0 or less, more preferably 1.0 or more and 5.0 or less, more preferably 1.2 or more and 4.0 or less, more preferably 1.5 or more and 3.5 or less, more preferably 1.6 or more and 3.4 or less, and the most preferred range is 1.7 or more and 3.3 or less.

[0086] The lower limit of d is preferably 1.0, 2.0, 3.0, 4.0, and 5.0, respectively, and the upper limit is preferably 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, 6.8, 6.7, and 6.6, respectively. That is, d is preferably 1.0 or higher and 9.5 or lower, more preferably 1.0 or higher and 9.0 or lower, more preferably 1.0 or higher and 8.5 or lower, more preferably 1.0 or higher and 8.0 or lower, more preferably 1.0 or higher and 7.5 or lower, more preferably 2.0 or higher and 7.0 or lower, more preferably 3.0 or higher and 6.8 or lower, more preferably 4.0 or higher and 6.7 or lower, and the most preferred range is 5.0 or higher and 6.6 or lower.

[0087] The lower limit of c+d is preferably 1.2, 2.0, 4.0, 6.0, 6.5, 6.6, and 6.7, respectively, and the upper limit is preferably 20.0, 15.0, 12.5, 11.0, 10.2, 10.1, 10.0, and 9.9, respectively. That is, c+d is preferably 1.2 or higher and 20.0 or lower, more preferably 1.2 or higher and 15.0 or lower, more preferably 2.0 or higher and 12.5 or lower, more preferably 4.0 or higher and 11.0 or lower, more preferably 6.0 or higher and 10.2 or lower, more preferably 6.5 or higher and 10.1 or lower, more preferably 6.6 or higher and 10.0 or lower, and the most preferred range is 6.7 or higher and 9.9 or lower.

[0088] The lower limit of e is preferably 0.10, 0.20, 0.50, 0.80, 1.0, 1.5, and 1.6, respectively, and the upper limit is preferably 4.5, 4.0, 3.5, 3.0, 2.5, 2.4, 2.3, and 2.2, respectively. That is, e is preferably 0.10 or higher and 4.5 or lower, more preferably 0.10 or higher and 4.0 or lower, more preferably 0.20 or higher and 3.5 or lower, more preferably 0.50 or higher and 3.0 or lower, more preferably 0.80 or higher and 2.5 or lower, more preferably 1.0 or higher and 2.4 or lower, more preferably 1.5 or higher and 2.3 or lower, and the most preferred range is 1.6 or higher and 2.2 or lower.

[0089] The upper limit of f is preferably 1.8, 1.5, 1.0, 0.80, and 0.50, respectively, and the lower limit is preferably 0. That is, the more preferred range for f is above 0 and below 0.50, and the most preferred value is 0.

[0090] The lower limit of g is preferably 0.010, 0.020, or 0.030, and the upper limit is preferably 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, or 0.090. That is, g is preferably 0.010 or more and 2.0 or less, more preferably 0.010 or more and 1.0 or less, more preferably 0.010 or more and 0.50 or less, more preferably 0.010 or more and 0.40 or less, more preferably 0.010 or more and 0.30 or less, more preferably 0.010 or more and 0.20 or less, more preferably 0.020 or more and 0.10 or less, and the most preferred range is 0.030 or more and 0.090 or less.

[0091] The upper limit of h is preferably 4.0, 3.0, 2.0, 1.8, 1.5, 1.0, 0.80, and 0.50, respectively, and the lower limit is preferably 0. That is, the more preferred range for h is 0 or higher and 0.50 or lower, and the most preferred value is 0.

[0092] As X in formula (1), tungsten, antimony, zinc, magnesium, calcium, and cerium are preferred, with antimony and zinc being particularly preferred.

[0093] As Y in formula (1), sodium, potassium, and cesium are preferred, and potassium and cesium are even more preferred.

[0094] Z in formula (1) is preferably vanadium, copper, niobium, zirconium, calcium, beryllium, strontium, barium, lead, or phosphorus.

[0095] [Catalyst in the first layer]

[0096] In this invention, the active component of the catalyst contained in the first layer (the catalyst layer closest to the inlet side of the reactant gas) is preferably a catalyst as shown in formula (1-1). It should be noted that when filling three or more layers, it is preferable that the catalyst, except for the one closest to the outlet side, has the composition shown in formula (1-1).

[0097] [Equation 1-1]

[0098] Mo a1 Bi b1 Ni c1 Co d1 Fe e1 X f1 Cs g1 Z h1 O i1 (1-1)

[0099] In formula (1-1), Mo, Bi, Ni, Co, Fe, and Cs represent molybdenum, bismuth, nickel, cobalt, iron, and cesium respectively, X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium, Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, Cs, and X, a1, b1, c1, d1, e1, f1, g1, h1, and i1 represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, Cs, Z, and oxygen respectively. When a1 is set to 12, 0 < b1 ≤ 7.0, 0 ≤ c1 ≤ 10, 0 < d1 ≤ 10, 0 < c1 + d1 ≤ 20, 0 < e1 ≤ 5.0, 0 ≤ f1 ≤ 2.0, 0 < g1 ≤ 3.0, 0 ≤ h1 ≤ 5.0 are satisfied, and i1 is a value determined by the oxidation state of each element.

[0100] When a1 in formula (1-1) is 12, the preferred values of b1 to f1, h1, X, and Z, including the preferred modes, are the same as b to h, X, and Z in formula (1).

[0101] As the lower limit of g1, 0.0010, 0.0050, 0.010, 0.015, 0.020, 0.030 are preferably in sequence, and as the upper limit, 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, 0.090, 0.060 are preferably in sequence. That is, g1 is preferably 0.0010 or more and 2.0 or less, more preferably 0.0010 or more and 1.0 or less, more preferably 0.0010 or more and 0.50 or less, more preferably 0.0010 or more and 0.40 or less, more preferably 0.0050 or more and 0.30 or less, more preferably 0.010 or more and 0.20 or less, more preferably 0.015 or more and 0.15 or less, more preferably 0.020 or more and 0.090 or less, and the most preferred range is 0.030 or more and 0.060 or less.

[0102] [Catalyst closest to the outlet side]

[0103] In the present invention, the composition of the active component of the catalyst contained in the catalyst layer closest to the outlet side (the catalyst layer closest to the outlet side of the raw material gas for the reaction) is preferably the catalyst represented by the following formula (1-2). For example, in the case of three-layer filling, it is preferably the case where the third layer is also the catalyst represented by formula (1-2), and in the case of further multi-layer filling, it is preferably the case where the catalyst closest to the outlet side is this catalyst.

[0104] [Formula 1-2]

[0105] Mo a2 Bi b2 Ni c2 Co d2 Fee2 X f2 K g2 Z h2 O i2 (1-2)

[0106] In the formula, Mo, Bi, Ni, Co, Fe and K represent molybdenum, bismuth, nickel, cobalt, iron and potassium respectively, X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium and titanium, Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, K and X, a2, b2, c2, d2, e2, f2, g2, h2 and i2 represent the atomic numbers of molybdenum, bismuth, nickel, cobalt, iron, X, K, Z and oxygen respectively. When a2 = 12, 0 < b2 ≤ 7.0, 0 ≤ c2 ≤ 10, 0 < d2 ≤ 10, 0 < c2 + d2 ≤ 20, 0 < e2 ≤ 5.0, 0 ≤ f2 ≤ 2.0, 0 ≤ g2 ≤ 3.0, 0 ≤ h2 ≤ 5.0, and i2 = the value determined by the oxidation state of each element.

[0107] When a2 = 12 in formula (1-2), the preferred values of b2 to f1, h2, X and Z, including the preferred modes, are the same as those of b to h, X and Z in formula (1).

[0108] As the lower limit of g2, 0.0010, 0.0050, 0.010, 0.015, 0.020, 0.030, 0.040, 0.050 are preferably used in sequence, and as the upper limit, 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, 0.10 are preferably used in sequence. That is, g2 is preferably 0.0010 or more and 2.0 or less, more preferably 0.0010 or more and 1.0 or less, more preferably 0.0050 or more and 0.50 or less, more preferably 0.010 or more and 0.40 or less, more preferably 0.020 or more and 0.30 or less, more preferably 0.030 or more and 0.20 or less, more preferably 0.040 or more and 0.15 or less, and the most preferred range is 0.050 or more and 0.10 or less.

[0109] The shape of the catalyst contained in the catalyst layer used in this application is not particularly limited, and spherical, cylindrical, ring-shaped, powdery, etc. can be used, and spherical is particularly preferred.

[0110] It should be noted that in the case of two-layer filling, the catalyst contained in the upper layer and the catalyst contained in the lower layer can both be diluted with an inert substance, and a method in which neither the upper layer nor the lower layer is diluted is more preferred.

[0111] The preferred range for the dilution rate di based on the inactive substance is described below. The dilution rate mentioned here refers to a numerical value representing the mass ratio of the catalyst to the catalyst layer composed of the catalyst and the inactive substance. For example, a catalyst layer of 80% mass dilution means that the catalyst is 80% by mass and the inactive substance is 20% by mass. It should be noted that, as explained in the catalyst manufacturing method described later, when a catalyst is prepared by supporting the catalytically active component on an inactive support, the dilution rate is calculated based on the mass of the catalyst containing the inactive support. Hereinafter, preferred methods are described using the cases of n=2 and 3 as examples, but the essence of this application is to ensure that the filling length of other catalyst layers after dividing the reaction tube into n equal parts in the gas flow direction falls within a specified range relative to the filling length of the nth catalyst layer, and therefore it is not limited to this.

[0112] It should be noted that the preferred embodiments of this application are as follows (1) to (2).

[0113] 1) n=2, the upper layer is a catalyst containing the catalytic active ingredient shown in formula (1-1) with a dilution rate of 100% by mass, and the lower layer is a catalyst containing the catalytic active ingredient shown in formula (1-2) with a dilution rate of 100% by mass.

[0114] 2) n=3, the middle layer is a catalyst containing the catalytically active component shown in formula (1-1), with a dilution rate of 100% by mass, the upper layer is a catalyst obtained by diluting the middle layer catalyst with an inactive substance, and the lower layer is a catalyst containing the catalytically active component shown in formula (1-2), with a dilution rate of 100% by mass.

[0115] Alternatively, there is a filling method in which an inactive material layer is provided at a location closer to the inlet side than the catalyst layer in the reaction tube. This filling method can be used as long as it does not impede the effectiveness of the present invention; a method without this inactive material layer is preferred.

[0116] The aforementioned inactive substances include known materials such as silicon dioxide, aluminum oxide, titanium dioxide, zirconium oxide, niobium oxide, silicon dioxide-alumina, silicon carbide, carbides, magnesium oxide, and mixtures thereof. Among these, silicon dioxide, aluminum oxide, or mixtures thereof are preferred, particularly preferred, and most preferably, a mixture of silicon dioxide and aluminum oxide.

[0117] Furthermore, the shape of the inactive substance is not particularly limited, but it is preferably spherical, with an average particle size of 3 mm to 10 mm, more preferably 3.5 mm to 9 mm, and particularly preferably 4 mm to 8 mm.

[0118] [Regarding the manufacturing method of catalysts]

[0119] The catalyst used in this application can be manufactured, for example, by the following processes a) to e).

[0120] <Process a) Preparation>

[0121] Generally, there are no particular restrictions on the starting materials of the elements constituting the catalytically active components. As raw materials for molybdenum, molybdenum oxides such as molybdenum trioxide; molybdic acids or their salts such as molybdic acid and ammonium molybdate; and molybdenum-containing heteropoly acids or their salts such as phosphomolybdic acid and silicomolybdic acid are preferred. When ammonium molybdate is used, a high-performance catalyst can be obtained. In particular, ammonium molybdate exists in various compounds such as diammonium molybdate, tetraammonium molybdate, and heptamolybdate, with heptamolybdate being the most preferred.

[0122] As raw materials for bismuth, bismuth salts such as bismuth nitrate, bismuth subcarbonate, bismuth sulfate, and bismuth acetate can be used; bismuth trioxide, metallic bismuth, etc., are preferred, as bismuth nitrate can be used to obtain high-performance catalysts. As raw materials for iron, cobalt, nickel, and other elements, oxides or nitrates, carbonates, organic acid salts, hydroxides, etc., or mixtures thereof, which can form oxides by strong heating, can generally be used. For example, iron raw materials are dissolved and mixed with cobalt and / or nickel raw materials in water at a desired ratio at 10–80°C, and then mixed with separately prepared aqueous solutions or slurries of molybdenum and Z raw materials at 20–90°C. After heating and stirring at 20–90°C for about 1 hour, an aqueous solution containing dissolved bismuth raw materials and, as needed, X and Y raw materials are added to obtain an aqueous solution or slurry containing catalyst components. Hereinafter, both are collectively referred to as formulation (A).

[0123] Here, the formulation (A) does not necessarily need to contain all the constituent elements of the catalytically active components; some elements or amounts may be added in subsequent processes. Furthermore, when preparing the formulation (A), if the amount of water used to dissolve each component raw material and / or the sufficient acid concentration in the aqueous solution required to dissolve the raw material when adding acids such as sulfuric acid, nitric acid, hydrochloric acid, tartaric acid, or acetic acid for dissolution is not suitable within, for example, a range of 5% to 99% by mass, the formulation (A) may sometimes become a clay-like mass. In this case, an excellent catalyst cannot be obtained. As the form of the formulation (A), an aqueous solution or slurry is preferred because it yields an excellent catalyst.

[0124] <Process b) Drying>

[0125] Next, the prepared liquid (A) obtained above is dried to produce a dried powder. There are no particular limitations on the drying method, as long as it can completely dry the prepared liquid (A); examples include drum drying, freeze drying, spray drying, and evaporative drying. In this invention, spray drying, which can dry a slurry into powder or particles in a short time, is particularly preferred. The drying temperature of the spray dryer varies depending on the slurry concentration and feed rate, and the temperature at the dryer outlet is approximately 70-150°C. Furthermore, it is preferable to dry the powder so that the average particle size of the resulting dried powder is 10-700 μm. This yields dried powder (B).

[0126] <Process c) Pre-firing>

[0127] The resulting dry powder (B) is calcined in air at 200°C to 600°C, preferably 300°C to 600°C, thereby improving the catalyst's formability, mechanical strength, and catalytic performance. The calcination time is preferably 1 hour to 12 hours. This yields pre-calcined powder (C).

[0128] <Process d) Molding>

[0129] There are no particular limitations on the molding method. When molding into cylindrical or ring shapes, methods such as tablet molding machines or extrusion molding machines are preferred. Further preferred is the molding into spherical shapes, where the pre-fired powder (C) can be molded into spherical shapes using a molding machine. A preferred method is to load the pre-fired powder (C) (containing molding aids and strength enhancers as needed) onto a carrier such as inactive ceramics. Here, as a loading method, methods such as rolling granulation, centrifugal flow coating devices, and washing methods are widely known. There are no particular limitations as long as the pre-fired powder (C) can be uniformly loaded onto the carrier. Considering the catalyst manufacturing efficiency and the performance of the prepared catalyst, a more preferred method is the following: In a device with a flat or convex disc at the bottom of a fixed cylindrical container, the disc is rotated at high speed, thereby vigorously agitating the carrier filled into the container by the repeated rotation and revolution of the carrier itself, and adding the pre-fired powder (C) and, as needed, molding aids and / or strength enhancers, thereby loading the powder components onto the carrier.

[0130] Furthermore, a binder is preferably used during loading. Specific examples of usable binders include water, ethanol, methanol, propanol, polyols, polyvinyl alcohol as a polymeric binder, and aqueous silica gel solution as an inorganic binder. Ethanol, methanol, propanol, and polyols are preferred, and glycols such as ethylene glycol and triols such as glycerol are more preferred. By using an appropriate amount of aqueous glycerol solution, the formability becomes good, and a high-performance catalyst with high mechanical strength can be obtained. Specifically, when using an aqueous solution with a glycerol concentration of 5% by mass or more, a particularly high-performance catalyst can be obtained. The amount of these binders is typically 2 to 80 parts by mass relative to 100 parts by mass of the pre-calcined powder (C). The inactive support is typically a support with a diameter of about 2 to 8 mm, on which the pre-calcined powder (C) is loaded. Its loading rate is determined considering the catalyst usage conditions, such as the space velocity of the reactants and the concentration of the reactants, and is typically 20% to 80% by mass. Here, the loading rate is expressed by the following formula.

[0131] Load factor (mass%) =

[0132] 100 × [mass of pre-fired powder (C) used for molding / (mass of pre-fired powder (C) used for molding + mass of inactive carrier used for molding)] (2)

[0133] <Step e) Formal Firing>

[0134] The molded body (D) obtained by step d) tends to exhibit improved catalytic activity and selectivity when fired at a temperature of 200-600°C for approximately 1-12 hours. The firing temperature is preferably 400°C or higher and 600°C or lower, more preferably 500°C or higher and 600°C or lower. Air is readily available as the circulating gas and is therefore preferred. In addition, nitrogen, carbon dioxide, nitrogen oxide-containing gases used to form a reducing atmosphere, ammonia-containing gases, hydrogen, and mixtures thereof can also be used as inactive gases. The catalyst (E) is thus obtained.

[0135] [A method for manufacturing a preferred CB catalyst is provided]

[0136] To obtain a catalyst with manufacturing parameters T that satisfy formula (I), a low CB is generally preferred. The following methods can be exemplified as methods for manufacturing catalysts with low CB. These methods can also be used individually or in combination.

[0137] (1) The first method is as follows: In the preparation process of preparing a liquid by adding each of the supply source compounds containing molybdenum, bismuth and iron to a solvent or solution and integrating and heating, the pH of the liquid is adjusted to a range of 1.0 to 7.5, more preferably to a range of 3.0 to 6.0, before the iron raw material is added. As a method for adjusting the pH, as described later, methods such as lowering the pH by adding nitric acid or increasing the pH by adding ammonia are examples.

[0138] Regarding pH adjusters, in methods for lowering pH, common acids used by those skilled in the art for adjusting pH, such as nitric acid, sulfuric acid, hydrochloric acid, and oxalic acid, which are commonly used as catalyst raw materials, can be used. Furthermore, as long as the elemental composition of the catalytically active components described later is not altered, pH adjusters that leave elemental residues after calcination, such as phosphoric acid, boric acid, molybdic acid, and ferric nitrate, can also be used; nitric acid is most preferred. In methods for raising pH, common bases used by those skilled in the art for adjusting pH, such as ammonia, pyridine, and ammonium carbonate aqueous solutions, which are commonly used as catalyst raw materials, can be used. Furthermore, as long as the elemental composition of the catalytically active components described later is not altered, pH adjusters that leave elemental residues after calcination, such as potassium hydroxide and cesium hydroxide, can also be used; ammonia is most preferred.

[0139] Furthermore, when implementing this method, the preferred embodiment is to prepare the slurry by adding iron raw material and stirring it before adding bismuth raw material to the mixing solution.

[0140] When adding the pH adjuster, for example, at a rate of 0.01~5.00 kW / m 3 The stirring power is used to stir the mixture while it is being added. The lower limit of the stirring power is preferably 0.05 kW / m³. 3 0.10kw / m 3 0.50kw / m 3 1.00kw / m 3 The upper limit for stirring power is preferably 4.50 kW / m³. 3 4.00kw / m 3 3.50kw / m 3 3.00kw / m 3 That is, the optimal range for stirring power is 1.00~3.00 kW / m³. 3 .

[0141] Regarding the addition time of the pH adjuster, it is between 1 second and 5 minutes. The lower limit of the addition time is preferably 5 seconds, 10 seconds, or 15 seconds, and the upper limit is preferably 4 minutes, 3 minutes, 2 minutes 30 seconds, 2 minutes, 1 minute 30 seconds, 1 minute, 45 seconds, or 30 seconds. That is, the most preferred addition time range is 15 to 30 seconds.

[0142] The temperature of the preparation solution used when adding pH adjuster is 5~80℃. The lower limit of the liquid temperature is preferably 10℃, 20℃, or 30℃, and the upper limit of the liquid temperature is preferably 70℃, 60℃, 50℃, or 40℃. That is, the optimal range of liquid temperature is 30~40℃.

[0143] (2) The second method is to optimize the rotational speed of the atomizer during spray drying. The optimal rotational speed of the atomizer is affected by the structure of the atomizer and spray dryer, the temperature, pH, viscosity of the liquid to be dried, and the mixing ratio of the catalyst components, etc., and therefore cannot be generalized. It is preferably 10,000 rpm or more and 18,000 rpm or less. The more preferred upper limit of the atomizer rotational speed is 17,000 rpm, particularly preferred is 16,000 rpm, and most preferably is 15,000 rpm. In addition, the more preferred lower limit is 11,000 rpm, particularly preferred is 12,000 rpm, and most preferably is 13,000 rpm. That is, the optimal range of the atomizer rotational speed is 13,000 rpm or more and 15,000 rpm or less.

[0144] Furthermore, the atomizer rotation speed is also expressed by relative centrifugal acceleration, preferably 6000G or higher and 20000G or lower. More preferably, the lower limits are 7500G, 8500G, and 10000G, respectively, and more preferably, the upper limits are 18000G, 16000G, and 14000G, respectively. That is, the optimal range for the atomizer rotation speed is 10000G or higher and 14000G or lower.

[0145] Furthermore, the temperature of the hot air supplied to the spray dryer (hereinafter sometimes referred to as the inlet temperature) and the outlet temperature of the spray dryer (hereinafter sometimes referred to as the outlet temperature) also affect the aforementioned parameters (CB, manufacturing parameter T). The inlet temperature is preferably 180°C or higher and 320°C or lower. More preferably, the lower limits are 200°C, 220°C, and 230°C, and more preferably, the upper limits are 300°C, 280°C, and 270°C, respectively. That is, the most preferably inlet temperature is 230°C or higher and 270°C or lower.

[0146] Furthermore, the outlet temperature is preferably 100°C or higher and 150°C or lower. More preferably, the lower limits are 101°C, 102°C, 103°C, 104°C, and 105°C, respectively, and more preferably, the upper limits are 140°C, 130°C, and 120°C, respectively. That is, the inlet temperature is most preferably 105°C or higher and 120°C or lower.

[0147] The difference between the inlet and outlet temperatures is preferably 30°C or higher and 220°C or lower. More preferably, the lower limits are 50°C, 80°C, 100°C, and 120°C, and more preferably, the upper limits are 200°C, 180°C, 165°C, and 150°C, respectively. In other words, the most preferably difference between the inlet and outlet temperatures is 120°C or higher and 150°C or lower.

[0148] Furthermore, in the method for preparing the catalyst precursor of the present invention, the range of the parameter SD given by the following formula is preferably 22 or more and 51 or less. More preferably, the lower limit is 26, 28, 30, 32, 34, and 35, and more preferably, the upper limit is 48, 44, 42, and 40, respectively. That is, the most preferably, SD is 35 or more and 40 or less.

[0149] SD = 51.3 + 0.0766 × {(Inlet temperature of spray dryer, unit: °C) - (Outlet temperature of spray dryer, unit: °C)} - 0.00173 × (Atomizer speed, unit: rpm)

[0150] (3) The third method relates to the composition of the active component of the catalyst and is a method for controlling it in more detail. Specifically, it is controlled by one or a combination of the following composition ratios. That is, in the aforementioned composition formula (1), the upper limit of e / b is preferably 2.90, more preferably 2.80, and the lower limit of e / b is preferably 0.10, 0.50, 1.00, 1.40, 1.50, and 1.90, respectively. Therefore, e / b is preferably 0.10 or more and 2.90 or less, more preferably 0.50 or more and 2.90 or less, more preferably 1.00 or more and 2.90 or less, more preferably 1.40 or more and 2.90 or less, more preferably 1.50 or more and 2.90 or less, and particularly preferably 1.90 or more and 2.80 or less.

[0151] The upper limit of d / b is preferably 9.0, 8.0, and 7.0, respectively, and the lower limit of d / b is preferably 2.0, 3.0, 4.0, 5.0, 5.5, and 6.5, respectively. Therefore, d / b is preferably 2.0 or higher and 9.0 or lower, more preferably 3.0 or higher and 9.0 or lower, more preferably 4.0 or higher and 9.0 or lower, more preferably 5.0 or higher and 9.0 or lower, more preferably 5.5 or higher and 8.0 or lower, and particularly preferably 6.5 or higher and 7.0 or lower.

[0152] The upper limits of c / e are preferably 4.0, 3.0, 2.5, and 2.0, respectively, and the lower limits of c / e are preferably 1.0, 1.5, 1.7, and 1.9, respectively. Therefore, c / e is preferably 1.0 or higher and 4.0 or lower, more preferably 1.5 or higher and 3.0 or lower, more preferably 1.7 or higher and 2.5 or lower, and particularly preferably 1.9 or higher and 2.0 or lower.

[0153] The upper limit of c / d is preferably 2.0, 1.0, and 0.8, respectively, and the lower limit of c / d is preferably 0.1 and 0.3, respectively. Therefore, c / d is preferably 0.1 or higher and 2.0 or lower, more preferably 0.1 or higher and 1.0 or lower, and particularly preferably 0.3 or higher and 0.8 or lower.

[0154] The upper limit of g / d is preferably 0.100, 0.050, 0.040, 0.030, 0.020, and 0.015, respectively, and the lower limit of g / d is preferably 0.007, 0.008, 0.009, 0.010, and 0.011, respectively. Therefore, g / d is preferably 0.007 or more and 0.100 or less, more preferably 0.007 or more and 0.050 or less, more preferably 0.008 or more and 0.040 or less, more preferably 0.009 or more and 0.030 or less, more preferably 0.010 or more and 0.020 or less, and particularly preferably 0.011 or more and 0.015 or less.

[0155] The upper limit of g / c is preferably 0.040, 0.035, and 0.030, respectively, and the lower limit of g / c is preferably 0.015, 0.020, and 0.025, respectively. Therefore, g / c is preferably 0.015 or more and 0.040 or less, more preferably 0.020 or more and 0.035 or less, and particularly preferably 0.025 or more and 0.030 or less.

[0156] (4) The fourth method is to control the firing temperature, firing time, or firing atmosphere of the pre-firing or formal firing, or both, as described below. The firing temperature is set to 200°C or higher and 600°C or lower, preferably 300°C or higher and 550°C or lower, more preferably 460°C or higher and 550°C or lower. The firing time is set to 0.5 hours or higher, preferably 1 hour or higher and 40 hours or lower, more preferably 2 hours or higher and 15 hours or lower, and most preferably 2 hours or higher and 9 hours or lower. As for the firing atmosphere, the oxygen concentration is set to 10% by volume or higher and 40% by volume or lower, preferably 15% by volume or higher and 30% by volume or lower, and most preferably an air atmosphere.

[0157] (5) The fifth method is: during the pre-calcination or formal calcination, or both, controlling the rate at which the temperature of the catalyst surface decreases from the highest temperature reached in the calcination process (pre-calcination temperature or formal calcination temperature) to room temperature. That is, the cooling rate is set to 1°C / min or more and 200°C / min or less, preferably 5°C / min or more and 150°C / min or less, more preferably 10°C / min or more and 120°C / min or less, and most preferably 50°C / min or more and 100°C / min or less. Cooling methods commonly used in industry to achieve the above-mentioned cooling rate range, such as exposing the calcined catalyst taken from the calcination furnace to an inactive atmosphere or a mist formed by an inactive solvent, and methods for rapidly moving the calcined catalyst to a pre-cooled chamber, are all within the scope of this invention.

[0158] (6) The sixth method is a method of controlling the mechanical impact and shear stress, etc., on the catalyst precursor and / or particles formed in each process, as described below. The mechanical impact and shear stress, etc., are preferably controlled to be below 100 kgf, more preferably below 50 kgf, more preferably below 20 kgf, even more preferably below 10 kgf, and most preferably below 5 kgf.

[0159] (7) The seventh method is: a method using reagent-grade high-purity raw materials. The details are not limited, for example, the raw materials used are sulfur and its compounds, lithium, halogens and their compounds, and lead with a content of less than 10,000 ppm by weight, preferably less than 1,000 ppm by weight, more preferably less than 100 ppm by weight, and most preferably less than 10 ppm by weight.

[0160] (8) The eighth method is a method of controlling the reaction time and / or slurrying time of cobalt and nickel raw materials in the mixing vessel with other raw materials in the catalyst preparation process described later, in order to minimize these timeframes. More specifically, it is a method of shortening the aforementioned residence time in the presence of cobalt and nickel raw materials when no metal salt raw materials other than molybdenum and alkali metals are present in the mixing vessel, or a method of shortening the aforementioned residence time in the presence of cobalt and nickel raw materials when the pH in the mixing vessel falls within a specific range. The aforementioned residence time is preferably 24 hours or less, more preferably 1 hour or less, more preferably 30 minutes or less, and most preferably 10 minutes or less. The pH range of the solution in the mixing vessel is preferably 2 or more and 10 or less, more preferably 2 or more and 8 or less, and most preferably 3 or more and 7 or less. The same applies to iron and bismuth raw materials, and molybdenum and bismuth raw materials.

[0161] (9) As a ninth method, the following can be listed: in the catalyst preparation process described later, a method in which each raw material is added all at once instead of in batches during the preparation process, or a method in which the concentration of nitric acid in the preparation solution is reduced. The method of adding all raw materials at once refers to adding the subsequent raw materials only after all the required amounts of each raw material have been added. In addition, regarding the concentration of nitric acid in the preparation solution, the concentration of nitrate ions in the preparation solution when it is completed and enters the next process is preferably adjusted to be 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, and most preferably 25% by mass or less.

[0162] [Concentration of olefins in the feedstock]

[0163] The catalytic gas-phase oxidation reaction of olefins in this invention is carried out as follows: at a temperature range of 250 to 450°C and a pressure of atmospheric pressure to 10 atm, preferably atmospheric pressure to 5 atm, and more preferably atmospheric pressure to 3 atm, a mixed gas comprising 6 to 12 vol% olefins (more preferably 6 to 10 vol%), 5 to 18 vol% molecular oxygen, 0 to 60 vol% water vapor, and 20 to 70 vol% inactive gases, such as nitrogen and carbon dioxide, as feed gases, is introduced onto the catalyst prepared as described above for a contact time of 0.5 to 10 seconds.

[0164] Furthermore, it is particularly preferred that the volume ratio of oxygen to olefin (oxygen / olefin) is 1.0 or more and 1.9 or less. More preferably, the upper limit of the oxygen / olefin ratio is 1.8, 1.7, and 1.6, with an even more preferred upper limit of 1.5. Furthermore, more preferably, the lower limit is 1.1, 1.2, and 1.3, respectively. Therefore, the most preferred range for the oxygen / olefin ratio is 1.3 or more and 1.5 or less.

[0165] It should be noted that in this invention, olefins also include alcohols that produce olefins in their intramolecular dehydration reactions, such as tert-butanol. From the viewpoint of production efficiency, it is preferable that the space velocity (SVo = reaction matrix supply rate (NL / hr) / catalyst filling volume (L)) of the reaction matrix (starting material) relative to the catalyst volume is high. However, if it is too high, the yield of the target product may decrease, the catalyst lifetime may be shortened, etc. Therefore, in practice, 40 to 200 hr is preferred. -1 More preferably 60~180hr -1 The range is specified. Here, NL represents the volume of the reaction matrix under standard conditions (1 atm, 0 °C). Furthermore, the conversion rate of the olefin is preferably around a conversion rate that yields a high yield of unsaturated aldehydes, typically 90 to 99.9%, preferably 95 to 99.5%, and more preferably 96 to 99%.

[0166] If the catalyst layer on the gas outlet side is excessively shortened to achieve the effects of this invention, the overall activity of the catalyst layer decreases, resulting in an excessive increase in the reaction bath temperature required to obtain the target product and achieve the commonly used feed conversion rate. Hot spots become high-temperature, leading to catalyst degradation and performance reduction. Furthermore, depending on the situation, early degradation of the catalyst on the gas inlet side may also generate high hot spots in the highly active catalyst layer on the gas outlet side, causing a sharp decrease in the selectivity and yield of the target product. Therefore, considering the balance between the catalysts on the gas inlet and gas outlet sides, it is necessary to avoid making the catalyst layer on the outlet side too short to prevent a decrease in the overall activity of the catalyst layer and an excessive increase in the reaction bath temperature. The reaction bath temperature is appropriately set according to the characteristics of the catalyst, the operating conditions, the required catalyst lifetime, etc., and therefore cannot be generalized. The preferred initial reaction bath temperature is 390°C or lower, with upper limits preferably 380°C, 370°C, 360°C, and 350°C, and most preferably 340°C or lower. The lower limit is 300°C or higher, more preferably 310°C or higher. It should be noted that the reaction bath temperature does not refer to the temperature during the heating process, but rather to the set temperature used to achieve an appropriate conversion rate of the raw materials.

[0167] Regarding the control of the filling length of the present invention, when the sum of the filling lengths of the catalyst layers from the first layer to the (n-1)th layer counted from the reactant gas inlet side is set as L, and the filling length of the nth catalyst layer counted from the reactant gas inlet side is set as Ln, L / Ln is preferably 0.1 or more and 1.0 or less. As preferred lower limits for L / Ln, 0.2, 0.3, and 0.4 are preferred sequentially, and 0.9 is preferred upper limits. Therefore, L / Ln is more preferably 0.2 or more and 1.0 or less, more preferably 0.3 or more and 1.0 or less, and particularly preferably 0.4 or more and 0.9 or less.

[0168] In industrial equipment, by implementing the manufacturing method described above, the yield of unsaturated aldehydes can be improved, and runaway from the highly active gas outlet side can be suppressed, enabling stable yields and operation in industrial equipment over a long period. This effect can be attributed to the fact that the occupancy of the catalyst layer with higher selectivity is higher than that of the catalyst layer with higher activity, thereby increasing the contribution of the catalyst with higher selectivity.

[0169] Example

[0170] The following examples illustrate embodiments, but the present invention is not limited to these embodiments as long as it does not depart from its spirit.

[0171] It should be noted that the definition of effective yield is as follows.

[0172] Propylene conversion rate (mol%)

[0173] = (Moles of propylene reacted / Moles of propylene supplied) × 100

[0174] Effective yield (moles %)

[0175] = (Moles of acrolein and acrylic acid produced / Moles of propylene supplied) × 100

[0176] Effective selection rate (moles %)

[0177] = (Moles of acrolein and acrylic acid produced / Moles of propylene reacted) × 100

[0178] [Manufacturing Example (Preparation of Catalyst)]

[0179] (Catalyst 1)

[0180] Catalyst 1 was prepared by the following method, based on the atomic ratio of the catalytically active components excluding oxygen:Mo:Bi:Fe:Co:Ni:Cs=12:0.7:2.0:6.2:2.0:0.04. Ammonium molybdate and cesium nitrate were dissolved in distilled water while heating and stirring to obtain an aqueous solution (preparation solution 1). Here, the distilled water used was 3.5 times the mass of ammonium molybdate, and the water temperature when adding the ammonium molybdate was 85°C. Separately, cobalt nitrate, nickel nitrate, and ferric nitrate were dissolved in distilled water to prepare an aqueous solution (preparation solution 2). Bismuth nitrate was dissolved in distilled water to make it acidic by adding concentrated nitric acid to prepare an aqueous solution (preparation solution 3). After adding concentrated nitric acid to the above preparation solution 1, preparation solutions 2 and 3 were mixed sequentially while stirring vigorously. The resulting suspension was dried using a spray dryer, and the resulting particles were calcined at 440°C for 6 hours to obtain a pre-calcined powder. Then, a powder containing crystalline cellulose mixed with pre-fired powder was supported on an inactive carrier (a 4.0 mm diameter spherical material with alumina and silica as the main components). The mass of the carrier and the mass of the pre-fired powder used in molding were adjusted to a loading rate of 60% by mass, as defined by the above formula. Using a 33% by mass aqueous glycerol solution as a binder, the supported catalyst was molded into spheres with a diameter of 5.1 mm. The supported catalyst was then calcined at a calcination temperature of 520 °C in air for 4 hours to obtain catalyst 1.

[0181] In a reaction tube with an inner diameter of 28.4 mm, 4 g of catalyst 1 was filled after being diluted with an inactive substance to prevent the formation of hot spots. The molar ratio of propylene:oxygen:nitrogen:water was set to 1:1.7:6.4:3.0, and the space velocity (SVo) of propylene was set to 400 hr. -1 The reaction bath temperature was varied (BT) and the reaction was carried out at 340℃~360℃. The propylene conversion rate was then calculated. The results and calculated CB are shown in Table 1-1.

[0182] [Table 1-1]

[0183]

[0184] (Catalyst 2)

[0185] In the manufacture of catalyst 1, the raw material was changed from cesium nitrate to potassium nitrate, with a composition ratio of Mo:Bi:Fe:Co:Ni:K = 12:0.8:1.6:6.1:2.9:0.07. The diameter of the inactive support was set to 4.5 mm, and the loading rate was set to 50% by mass. Otherwise, it was manufactured exactly the same as catalyst 1, yielding catalyst 2 with a diameter of 5.3 mm. The evaluation results and calculated CB, similar to those for catalyst 1, are shown in Table 1-2.

[0186] [Table 1-2]

[0187]

[0188] (Catalyst 3)

[0189] In the manufacture of catalyst 1, concentrated nitric acid was not added to the preparation solution 1 during the preparation process. The composition ratio was Mo:Bi:Fe:Co:Ni:Cs = 12:0.9:2.0:6.5:3.0:0.03. The diameter of the inactive support was set to 4.5 mm, the loading rate was set to 50% by mass, and the calcination temperature was set to 540 °C. Otherwise, it was manufactured exactly the same as catalyst 1, resulting in catalyst 3 with a diameter of 5.2 mm. The evaluation results and calculated CB, similar to those for catalyst 1, are shown in Tables 1-3.

[0190] [Table 1-3]

[0191]

[0192] (Catalyst 4)

[0193] In the manufacture of catalyst 1, concentrated nitric acid was not added to the preparation solution 1 during the preparation process. The raw material was changed from cesium nitrate to potassium nitrate, with a composition ratio of Mo:Bi:Fe:Co:Ni:K = 12:0.9:1.7:6.0:3.3:0.06. The loading rate was set to 60% by mass. Otherwise, it was manufactured exactly the same as catalyst 1, resulting in catalyst 4 with a diameter of 5.0 mm. The evaluation results and calculated CB, which were the same as those for catalyst 1, are shown in Tables 1-4.

[0194] [Table 1-4]

[0195]

[0196] (Catalyst 5)

[0197] In the manufacture of catalyst 2, concentrated nitric acid was not added to the preparation solution 1 during the preparation process. The composition ratio was Mo:Bi:Fe:Co:Ni:K = 12:0.9:2.0:6.5:3.0:0.05. The diameter of the inactive support was set to 4.5 mm, the loading rate was set to 50% by mass, and the calcination temperature was set to 550 °C. Otherwise, it was manufactured exactly the same as catalyst 2, resulting in catalyst 5 with a diameter of 5.2 mm. The evaluation results and calculated CB, similar to those for catalyst 1, are shown in Tables 1-5.

[0198] [Table 1-5]

[0199]

[0200] (Catalyst 6)

[0201] In the manufacture of catalyst 1, the firing temperature was set to 510°C. Otherwise, catalyst 6 was manufactured in exactly the same manner as catalyst 1. The results of the same evaluation as catalyst 1 and the calculated CB are shown in Tables 1-6.

[0202] [Table 1-6]

[0203]

[0204] (Catalyst 7)

[0205] In the manufacture of catalyst 2, the firing temperature was set to 530°C. Otherwise, catalyst 7 was manufactured in exactly the same manner as catalyst 2. The results of the same evaluation as catalyst 1 and the calculated CB are shown in Tables 1-7.

[0206] [Table 1-7]

[0207]

[0208] [Example 1]

[0209] A stainless steel reactor with an inner diameter of 25 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple with an outer diameter of 3 mm, is installed in the reactor. The reactor is filled with catalyst 1 dilution layer, catalyst 1, and catalyst 2 in the order from first to third layer, as shown in Table 2-1. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.7:1.0:2.4. The supplied raw materials are maintained at a propylene space velocity (SVo) of 90 hr. -1The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 50 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to carry out the oxidation reaction of propylene. The results of the reaction performance under different reaction bath temperatures are shown in Table 3-1. It should be noted that in Table 3-1, rows A1 and A2 without peak temperatures and reaction performance for each layer refer to: A1 was calculated by linear approximation using data from the temperature at which the effective yield reached its maximum (BT(A℃)) and temperatures lower than that, and A2 was calculated by linear approximation using data from A and temperatures higher than that (the same applies below).

[0210] [Table 2-1]

[0211]

[0212] [Table 3-1]

[0213]

[0214] [Example 2]

[0215] As shown in Table 2-2, the catalyst 3 dilution layer, catalyst 3, and catalyst 4 were filled in the order from the first layer to the third layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 1. The results of investigating the reaction performance by changing the reaction bath temperature are shown in Table 3-2.

[0216] [Table 2-2]

[0217]

[0218] [Table 3-2]

[0219]

[0220] [Example 3]

[0221] As shown in Table 2-3, the catalyst 3 dilution layer, catalyst 3, and catalyst 4 are filled in the order from the first layer to the third layer, so that the feedstock has a propylene space velocity (SVo) of 120hr. -1 The propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 1, except that the reaction bath temperature was varied to investigate the reaction results, which are shown in Table 3-3.

[0222] [Table 2-3]

[0223]

[0224] [Table 3-3]

[0225]

[0226] [Comparative Example 1]

[0227] As shown in Table 2-4, the catalyst 3 dilution layer, catalyst 3, and catalyst 5 were filled in the order from the first layer to the third layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 1. The results of investigating the reaction performance by varying the reaction bath temperature are shown in Table 3-4.

[0228] [Table 2-4]

[0229]

[0230] [Table 3-4]

[0231]

[0232] [Example 4]

[0233] A stainless steel reactor with an inner diameter of 25 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple with an outer diameter of 3 mm, is installed in the reactor. As shown in Table 2-5, catalyst 1 and catalyst 2 are filled in the order of first layer, second layer, respectively. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.7:0.7:2.5. The supply of raw materials is set at a propylene space velocity (SVo) of 140 hr. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 90 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to carry out the oxidation reaction of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-5.

[0234] [Table 2-5]

[0235]

[0236] [Table 3-5]

[0237]

[0238] [Example 5]

[0239] As shown in Table 2-6, catalyst 3 and catalyst 4 were filled in the order of first layer and second layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 4. The results of investigating the reaction performance by changing the reaction bath temperature are shown in Table 3-6.

[0240] [Table 2-6]

[0241]

[0242] [Table 3-6]

[0243]

[0244] [Comparative Example 2]

[0245] As shown in Table 2-7, the catalyst 3 dilution layer, catalyst 3, and catalyst 5 were filled in the order from the first layer to the third layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 4. The results of investigating the reaction performance by varying the reaction bath temperature are shown in Table 3-7.

[0246] [Table 2-7]

[0247]

[0248] [Table 3-7]

[0249]

[0250] [Example 6]

[0251] A stainless steel reactor with an inner diameter of 27 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple with an outer diameter of 3 mm, is installed in the reactor. The reactor is filled with catalyst 3 (dilution layer), catalyst 3, and catalyst 4 in the order from first to third layer, as shown in Table 2-8. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.6:0.8:3.3. The supply of raw materials is set at a propylene space velocity (SVo) of 84 h. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 35 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to induce the oxidation of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-8.

[0252] [Table 2-8]

[0253]

[0254] [Table 3-8]

[0255]

[0256] [Comparative Example 3]

[0257] As shown in Table 2-9, the catalyst 3 dilution layer, catalyst 3, and catalyst 5 were filled in the order from the first layer to the third layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 6. The results of investigating the reaction performance by varying the reaction bath temperature are shown in Table 3-9.

[0258] [Table 2-9]

[0259]

[0260] [Table 3-9]

[0261]

[0262] [Example 7]

[0263] A stainless steel reactor with an inner diameter of 28 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple with an outer diameter of 7 mm, is installed in the reactor. As shown in Table 2-10, catalyst 1 and catalyst 7 are filled in the order of first layer, second layer, respectively. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.7:1.2:3.0. The supply of raw materials is maintained at a propylene space velocity (SVo) of 180 hr. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 80 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to induce the oxidation of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-10.

[0264] [Table 2-10]

[0265]

[0266] [Table 3-10]

[0267]

[0268] [Example 8]

[0269] As shown in Table 2-11, catalyst 6 and catalyst 2 were filled in the order of first layer and second layer, and the propylene oxidation reaction was carried out under the exact same reaction conditions and aging method as in Example 7. The results of investigating the reaction performance by changing the reaction bath temperature are shown in Table 3-11.

[0270] [Table 2-11]

[0271]

[0272] [Table 3-11]

[0273]

[0274] The results summarized so far are shown in Table 4. To set T within an appropriate range and to appropriately calculate Savg based on the SVo of the reaction conditions, the filling method is controlled, thereby broadening (A2-A1) and obtaining a high effective yield.

[0275] [Table 4]

[0276]

[0277] [Manufacturing Example (Preparation of Catalyst)]

[0278] (Catalyst 8)

[0279] In the manufacture of catalyst 1, a powder containing crystalline cellulose mixed with pre-calcined powder was supported on an inactive carrier (a 4.5 mm diameter spherical material mainly composed of alumina and silica). The mass of the carrier and the mass of the pre-calcined powder used in molding were adjusted to a loading rate of 50% by mass, as defined by the above formula. A 30% by mass aqueous glycerol solution was used as a binder, and the supported catalyst was molded into spheres with a diameter of 5.3 mm to obtain the supported catalyst. The supported catalyst was calcined at a calcination temperature of 510 °C in an air atmosphere for 5 hours to obtain catalyst 8. The results of the same evaluation as catalyst 1 and the calculated CB are shown in Tables 1-8.

[0280] [Table 1-8]

[0281]

[0282] [Example 9]

[0283] A stainless steel reactor with an inner diameter of 25.4 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple for measuring the temperature of the catalyst layer, is installed in the reactor. A thermocouple sheath with an outer diameter of 3.2 mm is also installed, as shown in Table 2-12. Catalysts 8 and 7 are filled in the order of first layer, second layer, respectively. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.78:1.23:2.55. The supply of raw materials is set at a propylene space velocity (SVo) of 125 hr. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 57 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to carry out the oxidation reaction of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-12.

[0284] [Table 2-12]

[0285]

[0286] [Table 3-12]

[0287]

[0288] [Example 10]

[0289] A stainless steel reactor with an inner diameter of 24.9 mm and a jacket for circulating molten salt as a heat medium, and a thermocouple for measuring the temperature of the catalyst layer, is installed in the reactor. A thermocouple temperature sheath with an outer diameter of 7 mm is also installed. As shown in Table 2-13, the catalyst 8 dilution layer, catalyst 8, and catalyst 7 are filled in the order of first layer, second layer, and third layer. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from the air) = 1:1.68:1.05:2.43. The supplied raw materials are maintained at a propylene space velocity (SVo) of 100 hr. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 57 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to carry out the oxidation reaction of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-13.

[0290] [Table 2-13]

[0291]

[0292] [Table 3-13]

[0293]

[0294] [Example 11]

[0295] A stainless steel reactor with an inner diameter of 25.2 mm and a jacket for circulating molten salt as a heat medium, and a thermocouple for measuring the temperature of the catalyst layer, is installed in the reactor. A thermocouple temperature sheath with an outer diameter of 3.2 mm is also installed. As shown in Table 2-14, the catalyst 8 dilution layer, catalyst 8, and catalyst 7 are filled in the order of first layer, second layer, and third layer. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from air) = 1:1.75:1.15:2.20. The supply of this raw material is set at a propylene space velocity (SVo) of 115hr. -1The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 52 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to induce the oxidation of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-14.

[0296] [Table 2-14]

[0297]

[0298] [Table 3-14]

[0299]

[0300] [Example 12]

[0301] A stainless steel reactor with an inner diameter of 27.8 mm and a jacket for circulating molten salt as a heat transfer medium, and a thermocouple for measuring the temperature of the catalyst layer, is installed in the reactor. A thermocouple temperature sheath with an outer diameter of 3.2 mm is also installed. As shown in Table 2-15, the catalyst 8 dilution layer, catalyst 8, and catalyst 7 are filled in the order of first layer, second layer, and third layer. The supply rates of propylene, air, water, and nitrogen are set at a raw material molar ratio of propylene: oxygen (oxygen contained in the supplied air): water: nitrogen (nitrogen supplied separately from the air) = 1:1.63:0.63:3.36. The supplied raw materials are kept at a propylene space velocity (SVo) of 76hr. -1 The gas was circulated in a manner that allowed for complete gas flow. The pressure at the outlet of the reaction tube was set to 43 kPaG. After 300 hours of reaction, the temperature of the reaction bath was changed to carry out the oxidation reaction of propylene. The results of the reaction were investigated by changing the temperature of the reaction bath, as shown in Table 3-15.

[0302] [Table 2-15]

[0303]

[0304] [Table 3-15]

[0305]

[0306] The results of Examples 9 to 12 are summarized in Table 5. It can be confirmed once again that by appropriately calculating Savg based on the SVo of the reaction conditions in order to set the manufacturing parameters T of the present invention within an appropriate range, and by controlling the filling method, it is possible to broaden (A2-A1) and obtain a high effective yield.

[0307] [Table 5]

[0308]

[0309] This application is based on Japanese Patent Application No. 2023-191217, filed on November 9, 2023, the contents of which are incorporated herein by reference.

[0310] Industrial availability

[0311] According to this application, when using olefins or alcohols capable of producing olefins through intramolecular dehydration reactions as raw materials to manufacture corresponding unsaturated aldehydes and unsaturated carboxylic acids, high yields can be achieved over a wide reaction bath temperature range in industrial equipment. The wide range (A2-A1) means that high yields can be maintained over a broader range of reaction bath temperatures. That is, even when catalytic activity decreases and reaction bath temperatures rise over time due to prolonged equipment operation, high yields can be maintained for an extended period according to this invention.

Claims

1. A method for manufacturing an unsaturated aldehyde or unsaturated carboxylic acid, characterized in that, It is a method for manufacturing a corresponding unsaturated aldehyde or unsaturated carboxylic acid by partial oxidation of an olefin using a fixed-bed multi-tube reactor, and the manufacturing parameter T satisfies the following formula (I). T ≤ 20.5 (I) Wherein, T is calculated according to formula (IV) from the average filling parameter Savg and the space velocity SVo of the raw material. T (%·hr / ℃) = Savg (% / ℃) ÷ SVo ( / hr) × 10000 (IV) Savg is calculated according to formula (III) from the arithmetic mean of the filling parameters Si of all catalyst filling layers. Savg (% / ℃) = (S1 (% / ℃) + … + Sn (% / ℃)) ÷ n (III) Si is calculated according to formula (II) from the temperature sensitivity parameter CBi, dilution rate di, and filling length ratio Li of the catalyst in the i-th layer. Si (% / ℃) = CBi (% / ℃) × di (%) ÷ 100 × Li (II) CBi is a parameter related to the temperature sensitivity of the catalyst in the i-th layer, which is the change ratio of the raw material conversion rate with respect to the reaction bath temperature. In addition, n is the total number of catalyst layers in the reaction tube, and the subscript i is a natural number from 1 to n. The catalyst layer does not include an inert layer intentionally filled only with an inactive substance.

2. The method for manufacturing unsaturated aldehydes or unsaturated carboxylic acids according to claim 1, characterized in that, The manufacturing parameter T satisfies the following formula (V). 9.5 ≤ T ≤ 16.5 (V).

3. The method for producing unsaturated aldehydes or unsaturated carboxylic acids according to claim 1 or 2, characterized in that, The average filling parameter Savg satisfies the following formula (VI). 0.090 ≤ Savg ≤ 0.30 (VI).

4. The method for producing unsaturated aldehydes or unsaturated carboxylic acids according to claim 1 or 2, characterized in that, The catalytic active component contained in the catalyst layer closest to the inlet side of the raw material gas for the reaction has the composition shown in the following formula (1-1). Mo a1 Bi b1 Ni c1 Co d1 Feb e1 X f1 Cs g1 Z h1 O i1 (1-1) In formula (1-1), Mo, Bi, Ni, Co, Fe, and Cs respectively represent molybdenum, bismuth, nickel, cobalt, iron, and cesium. X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium. Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above Mo, Bi, Ni, Co, Fe, Cs, and X. a1, b1, c1, d1, e1, f1, g1, h1, and i1 respectively represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, Cs, Z, and oxygen. When a1 = 12, it satisfies 0 < b1 ≤ 7.0, 0 ≤ c1 ≤ 10, 0 < d1 ≤ 10, 0 < c1 + d1 ≤ 20, 0 < e1 ≤ 5.0, 0 ≤ f1 ≤ 2.0, 0 < g1 ≤ 3.0, 0 ≤ h1 ≤ 5.0, and i1 is a value determined by the oxidation state of each element.

5. The method for producing unsaturated aldehydes or unsaturated carboxylic acids according to claim 1 or 2, characterized in that, The catalytic active component contained in the catalyst layer closest to the outlet side of the raw material gas for the reaction has the composition shown in the following formula (1-2). Mo a2 Bi b2 Ni c2 Co d2 Feb e2 X f2 K g2 Z h2 O i2 (1-2) In formula (1-2), Mo, Bi, Ni, Co, Fe, and K respectively represent molybdenum, bismuth, nickel, cobalt, iron, and potassium; X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium; Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than the above-mentioned Mo, Bi, Ni, Co, Fe, K, and X; a2, b2, c2, d2, e2, f2, g2, h2, and i2 respectively represent the number of atoms of molybdenum, bismuth, nickel, cobalt, iron, X, K, Z, and oxygen. When a2 = 12, 0 < b2 ≤ 7.0, 0 ≤ c2 ≤ 10, 0 < d2 ≤ 10, 0 < c2 + d2 ≤ 20, 0 < e2 ≤ 5.0, 0 ≤ f2 ≤ 2.0, 0 ≤ g2 ≤ 3.0, 0 ≤ h2 ≤ 5.0 are satisfied, and i2 is a value determined by the oxidation states of the respective elements.

6. The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to claim 1 or 2, wherein, The equipment is operated by setting the reaction bath temperature to 310 °C or higher and 390 °C or lower.

7. The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to claim 1 or 2, wherein, The volume ratio of oxygen to olefin (oxygen / olefin) contained in the raw material gas for the reaction is 1.0 or higher and 1.9 or lower.

8. The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to claim 1 or 2, wherein, n catalyst layers are provided with respect to the gas flow direction in the reaction tube, where n is 2 or higher. When the sum of the filling lengths of the catalyst layers from the first layer to the (n - 1)th layer counted from the reaction gas inlet side is set as L and the filling length of the catalyst layer of the nth layer counted from the reaction gas inlet side is set as Ln, L / Ln is 0.1 or higher and 1.0 or lower.

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