TW201412696A - Production method for unsaturated aldehyde and/or unsaturated carboxylic acid - Google Patents

Abstract

A method whereby a fixed bed multitubuler reaction vessel is used, propylene, etc., is gas-phase catalytic oxidized using molecular oxygen-containing gas, and acrolein, acrylic acid, etc. are produced, and for which catalyst and catalytic filler specifications are designed so as to fulfill the specific conditions of 0.5 ≤ Cmax-Ccrs. Cmax: Starting-material conversion rate at which the yield of the target product is the greatest; Ccrs: Starting-material conversion rate when the magnitude relationship between Tin and Tout is inverted when the starting-material conversion rate is changed, when Tin is the maximum temperature for a catalyst layer (Zin) on the inlet side of the reaction vessel and Tout is the maximum temperature for a catalyst layer (Zout) on the outlet side.

Description

Method for producing unsaturated aldehyde and/or unsaturated carboxylic acid

The invention relates to a method for producing acrolein and acrylic acid by gas phase contact oxidation of propylene by molecular oxygen or molecular oxygen-containing gas, or using molecular oxygen or molecular oxygen-containing gas to isobutylene, three-stage A method in which butanol is subjected to vapor phase contact oxidation to produce methacrolein and methacrylic acid.

A method for producing a corresponding unsaturated aldehyde or unsaturated carboxylic acid using propylene, isobutylene or tertiary butanol as a raw material is widely practiced in the industry, and a local high temperature portion (hot spot) is formed in the catalyst layer. Bigger problem. The generation of hot spots can lead to shortened catalyst life, decreased yield due to excessive oxidation reaction, and uncontrolled reaction in the worst case. Therefore, the industry has proposed several techniques for suppressing hot spots. For example, Patent Document 1 discloses that a hot spot temperature is lowered by using a catalyst that adjusts the activity by changing the amount of the support, and by using a catalyst that adjusts the activity by changing the firing temperature of the catalyst. Technology. Patent Document 2 discloses a technique of using a catalyst for adjusting activity by changing the ratio of the apparent density of a catalyst. Patent Document 3 discloses that the activity is imparted by changing the content of the inert component of the catalyst molded body, changing the occupied volume of the catalyst molded body, the type and/or amount of the alkali metal, and the firing temperature of the catalyst. The technology of regulating the catalyst. Patent Document 4 discloses a technique in which a reaction belt for changing a volume occupied by a catalyst molded body is provided, and an inert material is mixed in at least one reaction belt. Patent Document 5 discloses a technique of using a catalyst that adjusts the activity by changing the firing temperature of a catalyst. Patent Document 6 discloses a technique of using a catalyst that adjusts the activity by changing the occupied volume of the catalyst, the firing temperature, and/or the type and amount of the alkali metal.

Patent Document 1: Japanese Patent No. 3775872

Patent Document 2: Japanese Patent Laid-Open Publication No. 2004-2209

Patent Document 3: Japanese Laid-Open Patent Publication No. 2001-328951

Patent Document 4: Japanese Laid-Open Patent Publication No. 2005-320315

Patent Document 5: Japanese Patent Laid-Open No. Hei 8-3093

Patent Document 6: Japanese Laid-Open Patent Publication No. 2001-226302

Even if the above method is used to suppress hot spots, it is not sufficient. Further, there is a possibility that the catalyst performance and the life expectancy expected in industrial equipment may not be obtained, and improvement is expected. E.g,

1) The method of using a catalyst for adjusting the activity by changing the occupied volume of the catalyst is a useful method for suppressing the hot spot, but there are tens of thousands of reaction tubes in the industrial equipment, and the inner diameter of the reaction tube is 20 mm. In the case of 30 mm, there is a case where an error of about ±0.2 mm is generated. It is known that if the catalyst is occupied by a small volume, the degree of influence can be neglected. However, if it is a catalyst having a large volume, that is, a catalyst having a large catalyst particle size, the influence may not be ignored. . Specifically, a bridge is formed in the reaction tube at the time of filling, and the bridge is required to be labor-intensive; the difference in the filling amount and the packing density causes a pressure loss to be easily uneven in each reaction tube. It causes uneven distribution of the flow rate of the raw material gas; and it also requires a lot of labor to correct the uneven distribution. It is easily conceivable that the problem becomes more pronounced when the shape of the catalyst is not spherical.

2) Further, in industrial equipment, not only the unevenness of the reaction tube diameter as described above but also the uneven heat dissipation capacity due to the structure of the reactor, and the temperature distribution of the heat medium in the horizontal direction and the vertical direction are generated. In the case of the gas flow rate distribution of each reaction tube, it is almost impossible to use the catalyst in the same state in all the reaction tubes. The present inventors analyzed the catalyst used in the industrial equipment, and as a result, found that the reaction tube in which the catalyst concentration is degraded at the inlet portion of the raw material gas, and The reaction tube in which the catalyst was slowly deteriorated as a whole, and the reaction tube in which the catalyst in the outlet portion of the raw material gas was further deteriorated from the catalyst in the inlet portion was surprisingly found. This finding suggests that there is a possibility that the temperature of the hot spot of the catalyst layer on the outlet side of the raw material gas is abnormally high, which may cause a runaway reaction in the worst case. The inventors of the present invention conceived that the reason is that due to the unevenness of the reaction tube diameter in the above industrial equipment, the heat dissipation capability due to the reactor structure is uneven, the temperature distribution of the heat medium in the horizontal direction and the vertical direction, and the reaction tubes. Since the gas flow rate distribution causes the conversion rates of the raw material hydrocarbons to be different and the shape of the temperature distribution to be different, it has been proposed to develop a technology that can be safely and stably maintained in industrial equipment and maintain a high yield in a long period of time.

The present inventors have found out that the industrial equipment is preferably operated at a raw material conversion rate in which the catalyst exhibits the maximum yield, although most of the reaction tubes do not exceed the catalyst used at the conversion rate of the raw material. The catalyst is selected in such a manner that the upper limit temperature is used. However, since the reaction conditions in the above industrial equipment are different, the reaction tube in which the conversion rate of the raw material such as propylene or the like is reduced in the entire reactor, and the raw material gas outlet side catalyst layer Zout The temperature exceeds the upper limit temperature of the catalyst, and as a result, there is a risk of insufficient reaction yield, insufficient catalyst life, and runaway reaction. As a method for solving the problem, the inventors of the present invention have found that the above problems can be solved by the following method, and the present invention is completed by using a catalyst layer having a plurality of catalyst layers formed along the flow direction of the material gas. The conversion of the raw material in the reverse direction of the maximum conversion of the raw material conversion rate to the target product yield, and the maximum temperature of the catalyst layer closest to the reaction gas inlet side and the reaction gas outlet side closest to the reaction gas outlet side The relationship between the rate and the specific conditions is designed to design the catalyst and catalyst filling method.

That is, the present invention relates to:

(1) A method for producing acrolein, acrylic acid, or methacrolein and methacrylic acid, which uses a fixed bed multitubular reactor, using a gas containing molecular oxygen to propylene, or selected from isobutylene and tertiary At least one of butanol is subjected to vapor phase contact oxidation to produce acrolein and acrylic acid, or methacrolein and methacrylic acid, A) A multilayer catalyst layer formed by dividing the material gas flow direction of the reaction tube into N layers (N is an integer of 2 or more), and the catalyst layer closest to the reaction gas inlet side of the catalyst layer is set to Zin The catalyst layer closest to the outlet side of the reaction gas is set to Zout, and B) is filled with the catalyst in such a manner that the activity of the catalyst filled in Zout is higher than that of the catalyst filled in Zin, so that the following formula (1) is satisfied. ): 0.5≦Cmax-Ccrs (1)

Cmax: the conversion rate of the raw material with the highest target product yield

Ccrs: the maximum temperature of the catalyst layer Zin is set to Tin, and the highest temperature of the catalyst layer Zout is set to Tout, so that when the conversion rate of the raw material changes, the relationship between the size of Tin and Tout is reversed;

(2) The method for producing acrolein and acrylic acid, or methacrolein and methacrylic acid according to (1), wherein 0.5≦Cmax-Ccrs≦10 is satisfied;

(3) The method for producing acrolein and acrylic acid, or methacrolein and methacrylic acid according to (1), wherein 0.5≦Cmax-Ccrs≦5 is satisfied;

(4) The method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to any one of the above (1) to (3), wherein N is 3 or less and the catalyst is filled in Zin. a firing temperature higher than a firing temperature of the catalyst filled in Zout, and further filling a mixture of the catalyst and the inert material molded body in Zin;

(5) The method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to any one of (1) to (4) above, wherein the catalyst is obtained by carrying the active powder on an inert substance. Spherical loading catalyst;

(6) The method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to any one of the above (1) to (5), wherein a particle diameter of a catalyst filled in each catalyst layer is The entire floor is uniform.

According to the present invention, ordinary industrial equipment can be produced as long as there is no special situation. The highest conversion rate of the raw material is carried out, and most of the catalyst charged in the reaction tube is reacted at the desired conversion rate of the raw material, and as a result, the hot spot temperature of the catalyst layer at the inlet portion of the raw material gas is higher than the raw material gas outlet. The state of the catalyst hot spot temperature on the side, but the reaction tube having a reduced conversion rate of the raw material due to the unique condition of the industrial equipment, as a result, the temperature of the catalyst filled in the reaction tube can be prevented from becoming substantially higher than the outlet side of the raw material gas. Acrolein and acrylic acid, or methacrolein and methacrylic acid can be produced in a high yield in a safe and stable manner by the phenomenon of abnormal reaction on the inlet side of the raw material gas.

Of course, such a phenomenon is not easy to be generated depending on the composition, shape, reaction conditions, and the like of the catalyst, and the degree is not the same, but it may be generalized, but when the inner diameter of the reaction tube to be used is 25 mm or more, This problem is more pronounced when the molar ratio of water to hydrocarbons in the raw material gas is 3.0 or less.

Next, preferred embodiments are described in the practice of the present invention.

The catalyst used in the method of the present invention can be produced by a known method, for example, by the following general formula.

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

(wherein, Mo, Bi, Ni, Co, Fe, O represent molybdenum, niobium, nickel, cobalt, iron and oxygen, respectively, and X represents a selected from the group consisting of tungsten, tantalum, tin, zinc, chromium, manganese, magnesium, and cerium oxide. At least one element selected from the group consisting of aluminum, lanthanum and titanium, Y represents at least one element selected from the group consisting of potassium, lanthanum, cerium and lanthanum, and a, b, c, d, f, g, h and x represent molybdenum, niobium and nickel. The atomic number of cobalt, iron, X, Y and oxygen, a=12, b=0.1~7, preferably b=0.5~4, c+d=0.5~20, more preferably c+d=1~ 12, f = 0.5 ~ 8, and more preferably f = 0.5 ~ 5, g = 0 ~ 2, particularly good for g = 0 ~ 1, h = 0.005 ~ 2, the best is h = 0.01 ~ 0.5, x = The value determined by the oxidation state of each element)

Here, the powder containing the catalytically active component can be coprecipitated by spray drying. The method can be prepared by a known method, and the obtained powder can be calcined at preferably 200 to 600 ° C, more preferably 300 to 500 ° C, and preferably in an air or nitrogen stream to obtain a catalytically active component ( Hereinafter, it is called a calcined powder).

The pre-baked powder obtained in this way can also be directly used as a catalyst, but considering the raw Productivity and workability are used as a catalyst for the present invention after molding. The shape of the molded article may be a spherical shape, a cylindrical shape, a ring shape, or the like, and is not particularly limited. The shape is selected in consideration of the production efficiency, mechanical strength, and the like of the catalyst, but is preferably spherical. In the molding, generally, a single pre-baked powder is used for molding, but a method such as preparing iron, cobalt, nickel, an alkali metal or the like into different particles into a pre-sintered powder may be used. The ratio is pre-mixed and formed, and the operation of carrying different types of pre-baked powder on an inert carrier may be repeated, and the pre-baked powder is molded into a plurality of layers. Further, at the time of molding, it is preferred to mix a molding aid such as crystalline cellulose and/or a strength improving agent such as ceramic whiskers. The amount of the molding aid and/or the strength improving agent to be used is preferably 30% by weight or less based on the calcined powder. Further, the molding aid and/or the strength improving agent may be previously mixed with the calcined powder before molding, or may be added simultaneously with or before the addition of the calcined powder to the molding machine.

The molding method is not particularly limited, and when it is formed into a cylindrical shape or a ring shape, it is preferably A method such as a tablet molding machine or an extrusion molding machine is used.

More preferably, it is formed into a spherical shape, and the calcined powder may be formed into a spherical shape by using a molding machine, but it is preferred to carry the calcined powder (including a molding aid and a strength improving agent as needed) on an inert ceramic. The method on the carrier. Here, the carrier method is not particularly limited as long as it can be uniformly carried on the carrier by a rolling granulation method, a method using a centrifugal flow coating device, a wash coat, or the like, but is not particularly limited. In consideration of the production efficiency of the catalyst or the like, it is preferable to use a device for providing a flat or concave-convex disk at the bottom of the fixed cylindrical container, and to rotate the disk at a high speed to utilize the carrier itself. Repeated rotation and revolutionary movements are invested in The carrier in the container is vigorously stirred, and a calcined powder and, if necessary, a molding aid and a strength improving agent are added thereto, whereby the powder component is carried on the carrier. Further, it is preferred to use a binder when carrying. Specific examples of the binder that can be used include water, ethanol, methanol, propanol, a polyhydric alcohol, a polyvinyl alcohol of a polymer binder, an aqueous solution of an inorganic binder, and the like, and preferably ethanol or methanol. The propanol or the polyhydric alcohol is preferably a diol such as ethylene glycol or a triol such as glycerin, and preferably an aqueous solution having a glycerin concentration of 5% by weight or more. By using an appropriate amount of an aqueous solution of glycerin, moldability is improved, and a catalyst having high mechanical strength, high activity, and high performance can be obtained.

The amount of the binder used is usually 2 to 60 parts by weight based on 100 parts by weight of the calcined powder, and preferably 10 to 30 parts by weight when using a glycerin aqueous solution. At the time of carrying, the binder may be preliminarily mixed with the calcined powder, or the binder may be added simultaneously when the pre-baked powder is supplied to the rolling granulator.

The inert carrier is usually used in a diameter of about 2 to 15 mm, and a pre-baked powder is placed thereon, and the amount of the carrier is determined in consideration of the catalyst use conditions, such as the space velocity and the hydrocarbon concentration of the raw material.

The formed catalyst is again fired before being used for the reaction. The firing temperature at the time of re-baking is usually 450 to 650 ° C, and the firing time is usually 3 to 30 hours, preferably 4 to 15 hours, and can be appropriately set depending on the reaction conditions to be used. At this time, it is preferable that the calcination temperature of the catalyst provided on the inlet side of the raw material gas is calcined at a temperature higher than the catalyst temperature on the gas outlet side to suppress the activity regardless of the composition of the catalyst. The firing environment may be any of an air environment and a nitrogen atmosphere, but it is preferably an air environment industrially.

The catalyst obtained in this manner can be used in the following steps to produce acrolein and acrylic acid by gas phase contact oxidation of propylene with molecular oxygen or molecular oxygen-containing gas; or using molecular oxygen or molecular oxygen-containing gas. Gas phase contact oxidation of isobutylene and tertiary butanol to produce methacrolein and methacrylic acid. In the production method of the present invention, the method of flowing the raw material gas may be a usual single-flow method or a circulation method, and it may be carried out under usual conditions, and is not particularly limited. For example, the mixed gas is formed in the following manner, and propylene, isobutylene, and tertiary butanol as starting materials are preferably 1 to 10% by volume, more preferably 4 to 9% by volume, and more preferably 3 to 9% by volume at normal temperature. ~20% by volume, more preferably 4 to 18% by volume, water vapor is preferably 0 to 60% by volume, more preferably 4 to 50% by volume, and inert gas such as carbon dioxide or nitrogen is preferably 20 to 80% by volume, more Preferably, it is 30 to 60% by volume, and the mixed gas is introduced into the catalyst of the present invention filled in the reaction tube at a pressure of 250 to 450 ° C, a pressure of normal pressure to 10 atm, and a space velocity of 300 to 5000 h ^-1 . Carry out the reaction. The above reaction can also be carried out by using a single catalyst for the catalyst layer. However, in the method of the present invention, the hot spot temperature can be lowered by providing a catalyst layer divided into N layers (N is an integer of 2 or more). .

Further, in the method of the present invention, among the catalyst layers formed by dividing the flow direction of the material gas in the reaction tube into a plurality of layers, the catalyst layer closest to the inlet side of the reaction gas is set to Zin, and is closest to the outlet side of the reaction gas. The catalyst layer is set to Zout, and the catalyst is filled in such a manner that the catalyst filled in Zout has a higher activity than the catalyst filled in Zin so as to satisfy the following formula (1).

0.5≦Cmax-Ccrs (1)

Cmax: The conversion rate of the raw material with the highest target product yield.

Ccrs: The maximum temperature of the catalyst layer Zin is set to Tin, and the maximum temperature of the catalyst layer Zout is set to Tout. When the conversion rate of the raw material is changed, the relationship between the size of Tin and Tout is reversed.

The formula (1) is preferably 0.5 ≦ Cmax-Ccrs ≦ 10, more preferably 0.5 ≦ Cmax-Ccrs ≦ 5.

More specifically, the catalyst composition on the inlet side of the raw material gas, the firing temperature, the mixing ratio with the inert material, the filling length, the catalyst composition on the outlet side of the raw material gas, the firing temperature, and the like are determined in such a manner as to satisfy 0.5 ≦ Cmax-Ccrs. Fill length. Further, Cmax-Ccrs may also vary depending on the elapsed time of operation. However, in order to exert the effects of the present invention, it is preferred to satisfy 0.5 ≦ Cmax for at least one year after the start of use of the catalyst, preferably until the catalyst is replaced. -Ccrs. The reason In the catalyst immediately after the start of use, there is a tendency that the conversion rate of the raw material is lowered, and in particular, the value of Zout is increased. Further, in general, with the passage of time, Cmax-Ccrs tends to decrease due to deterioration of the catalyst filled in Zin. Therefore, depending on the catalyst to be used, the effect of the present invention can be maintained for a long period of time by designing the filling method such that Cmax-Ccrs at the start of the reaction is greater than 0.5, preferably 1 or more. The above studies preferably use a laboratory device that can be tested under the same conditions to determine the catalyst filling conditions before being used in industrial equipment, and can also be combined with a computer simulation.

Computer simulation usually uses CFD (Computational Fluid Dynamics). The raw material conversion rate, acrolein and acrylic acid can be calculated by inputting the physical property value, reaction rate constant, reaction heat and the like of the catalyst into commercially available software for calculation. Rate, temperature distribution within the catalyst layer.

When Cmax or Ccrs is obtained in an industrial equipment or an experimental apparatus, the temperature distribution of the catalyst layer is measured by a thermocouple in a measurement range of 10 cm or less. If the measurement is performed in a measurement range of more than 10 cm, the temperature of the hot spot cannot be accurately grasped, which is not preferable. In addition, for the conversion rate of the raw material gas, the reaction bath temperature is intentionally changed, the conversion rate of the raw materials at each reaction bath temperature, the yield of the active ingredient under the conversion rate of each raw material, the hot spot temperature, and the mapping are plotted, and the data is interpolated. Find Cmax or Ccrs. More accurate data can be obtained by varying the reaction bath temperature to a measurement range of less than 5 °C.

According to the present invention, by setting 0.5 ≦ Cmax-Ccrs, even if there is a variation in the reaction temperature inside the reactor in the industrial equipment, a variation in the gas flow state, and a differential pressure difference between the respective reaction tubes, almost all the reaction tubes can be used. In the case where the temperature of the catalyst hot spot on the outlet side of the raw material gas (that is, Tout) is abnormally increased, the operation can be stably and safely performed. Further, by setting Cmax-Ccrs ≦ 5, it is possible to control Tin to a relatively low temperature.

As described above, although it is necessary to slightly adjust the catalyst filling method depending on the operating conditions, the firing temperature at the time of preparation of the catalyst used for the inlet side of the raw material gas is higher than that of the catalyst for the gas outlet side. The firing temperature at the time of preparation, and diluted with an inert substance, can be relatively Change the fill method easily.

Example

Hereinafter, the invention will be specifically described by way of examples, but the invention is not limited to the examples.

Further, the conversion ratio, selectivity and yield in the present invention are defined as follows, respectively.

Propylene conversion (% by mole) = (number of propylene moles in reaction / number of propylene moles supplied) × 100

Acrolein yield (% by mole) = (formed acrolein mole / supplied propylene moles) × 100

Acrylic acid yield (% by mole) = (molar number of acrylic acid generated / number of propylene moles supplied) × 100

In the case where the raw material uses isobutylene and/or tertiary butanol in place of propylene, acrolein may be replaced with methacrolein, and acrylic acid may be replaced with methacrylic acid.

Example 1

(Preparation of catalyst)

One side of the distilled water was heated and stirred, and 423.8 parts by weight of ammonium molybdate and 1.64 parts by weight of potassium nitrate were dissolved to obtain an aqueous solution (A1). Further, 302.7 parts by weight of cobalt nitrate, 162.9 parts by weight of nickel nitrate, and 145.4 parts by weight of iron nitrate were dissolved in 1000 parts by weight of distilled water to prepare an aqueous solution (B1), and distilled water adjusted to be acidic by adding 42 parts by weight of concentrated nitric acid. An aqueous solution (C1) was prepared by dissolving 164.9 parts by weight of cerium nitrate in 200 parts by weight. (B1) and (C1) were sequentially mixed in the aqueous solution (A1) while vigorously stirring, and the resulting suspension was dried using a spray dryer and baked at 440 ° C for 6 hours to obtain a pre-firing. Powder (D1). The composition ratio of the catalyst active component excluding oxygen at this time was Mo = 12, Bi = 1.7, Ni = 2.8, Fe = 1.8, Co = 5.2, and K = 0.15 in terms of atomic ratio.

Thereafter, 5 parts by weight of the crystalline cellulose is mixed in 100 parts by weight of the calcined powder. The powder is supported on an inert carrier (a spherical material having a diameter of 4.5 mm mainly composed of alumina and cerium oxide), and the weight of the carrier used in the molding is adjusted so as to be at a ratio of 50% by weight of the carrier. Pre-fired into powder weight. A 20% by weight aqueous solution of glycerin was used as a binder, and a spherical shape of 5.2 mm in diameter was supported to obtain a supporting catalyst (E1).

The catalyst (F1) was obtained by firing the carrier catalyst (E1) at a firing temperature of 530 ° C in an air atmosphere for 4 hours.

Next, each of the following solutions was prepared: one side of the distilled water was heated and stirred, and 423.8 parts by weight of ammonium molybdate and 1.08 parts by weight of potassium nitrate were dissolved to obtain an aqueous solution (A2). Further, 302.7 parts by weight of cobalt nitrate, 162.9 parts by weight of nickel nitrate, and 145.4 parts by weight of iron nitrate were dissolved in 1000 parts by weight of distilled water to prepare an aqueous solution (B2), and distilled water 200 adjusted to be acidic by adding 42 parts by weight of concentrated nitric acid. An aqueous solution (C2) was prepared by dissolving 164.9 parts by weight of cerium nitrate in parts by weight. (B2) and (C2) were sequentially mixed in the above aqueous solution (A2) while vigorously stirring, and the resulting suspension was dried using a spray dryer and baked at 440 ° C for 6 hours to obtain a pre-baking. Powder (D2). The composition ratio of the catalyst active component other than oxygen at this time was Mo = 12, Bi = 1.7, Ni = 2.8, Fe = 1.8, Co = 5.2, and K = 0.10 in terms of atomic ratio.

Thereafter, the powder obtained by mixing 5 parts by weight of the crystalline cellulose in 100 parts by weight of the calcined powder is supported on an inert carrier (spherical substance having a diameter of 4.5 mm containing alumina and ceria as a main component), and The weight of the carrier used in the molding and the weight of the calcined powder were adjusted so as to be a ratio of the carrier amount to 50% by weight. A 20% by weight aqueous solution of glycerin was used as a binder, and a spherical shape of 5.2 mm in diameter was supported to obtain a supporting catalyst (E2).

The catalyst (E2) was calcined at 530 ° C for 4 hours to obtain a catalyst (F2). The catalyst (E3) was calcined at 510 ° C for 4 hours to obtain a catalyst (F3).

(oxidation reaction test)

A raw material gas inlet side of a stainless steel reactor having a diameter of 25.4 mm, which is a jacket for circulating a molten salt of a heat medium and a thermocouple for measuring the temperature of the catalyst layer, is provided on the tube shaft, and the diameter is sequentially filled. 5.2 mm cerium oxide-alumina sphere 20 cm, as the oxidation catalyst first layer (raw material gas inlet side), the oxidation catalyst (F1) and the 5.2 mm diameter cerium oxide-alumina mixture inert carrier by weight ratio The diluted catalyst was mixed at 4:1 to 100 cm, and the oxidation catalyst (F3) as the oxidation catalyst second layer (gas outlet side) was 250 cm, and the reaction bath temperature was set to 330 °C. Here, a gas in which the supply amount of propylene, air, nitrogen, and water is set to a oxidizing reaction at a space velocity of 1500 h ^-1 is set in such a manner that the raw material molar ratio is propylene: oxygen: nitrogen: water = 1:1.7:8.8:1. The reactor outlet pressure was set to 70 kPaG, and 200 hours after the start of the reaction, the reaction bath temperature was changed in units of 2 ° C, and the conversion of the raw material, the yield of acrolein, the yield of acrylic acid, and the hot spot temperature were measured. (hereinafter referred to as reaction temperature change test), the raw material conversion rate was 97.8%, and the total yield of acrolein and acrylic acid was 91.8%. At this time, the reaction bath temperature was 330 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 434 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 378 ° C. In addition, the magnitude of the temperature of the two hot spots is related to the reversal when the conversion rate of the raw material is 95.5%. That is, Cmax-Ccrs = 2.3. The propylene conversion rate at the reaction bath temperature of 320 ° C was 93%, but the hot spot temperature of the catalyst layer on the gas inlet side was 352 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 401 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Example 2

In the oxidation reaction condition of the first embodiment, the catalyst filled in the inlet portion of the raw material gas is set as a dilution contact of F2 and a 5.2 mm diameter cerium oxide-alumina mixture inert carrier at a weight ratio of 4:1. The oxidation reaction of propylene was carried out in the same manner as in Example 1 except that the catalyst filled in the outlet portion of the raw material gas was set to 230 cm of F3 catalyst.

The reaction temperature change test was carried out, and as a result, the raw material conversion rate was 97.2%, and the total yield of acrolein and acrylic acid was 92.1% in total. At this time, the reaction bath temperature was 332 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 431 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 372 ° C. In addition, the magnitude of the temperature of the two hot spots is reversed when the conversion rate of the raw material is 95.1%. That is, Cmax- Ccrs = 2.1. The propylene conversion rate at the reaction bath temperature of 322 ° C was 93%, but the hot spot temperature of the catalyst layer on the gas inlet side was 353 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 398 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Example 3

In Example 2, the gas of the supply amount of propylene, air, nitrogen, and water was set at a space velocity of 1500 h ^{-1 in} such a manner that the raw material molar ratio was propylene: oxygen: nitrogen: water = 1: 1.8: 10: 1.5. The test was carried out in the same manner as in Example 2 except that the pressure at the outlet of the reactor was changed to 55 kPaG. The conversion of the raw material was 97.9%, and the total yield of acrolein and acrylic acid was 92.3% at the maximum. At this time, the reaction bath temperature was 330 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 424 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 370 ° C. In addition, the magnitude of the temperature of the two hot spots is reversed when the conversion rate of the raw material is 96.2%. That is, Cmax-Ccrs = 1.7. The propylene conversion rate at the reaction bath temperature of 318 ° C was changed to 95%, but the hot spot temperature of the catalyst layer on the gas inlet side was 348 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 410 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Example 4

In the same manner as in Example 3 except that the oxidation reactor was introduced at a space velocity of 1715 h ^-1 and the reactor outlet pressure was 70 kPaG, the conversion of the raw material was 97.8%, and acrolein was used. The total yield of acrylic acid was 91.6% in total. At this time, the reaction bath temperature was 332 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 429 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 371 ° C. In addition, the magnitude of the temperature of the two hot spots is reversed when the conversion rate of the raw material is 96.1%. That is, Cmax-Ccrs = 1.7. The propylene conversion rate at the reaction bath temperature of 319 ° C was changed to 95%, but the hot spot temperature of the catalyst layer on the gas inlet side was 350 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 414 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Example 5

In Example 2, the gas of the supply amount of propylene, air, nitrogen, and water was set at a space velocity of 2000 h ^{-1 in} such a manner that the raw material molar ratio was propylene: oxygen: nitrogen: water = 1:1.9:12:1. The test was carried out in the same manner as in Example 2 except that the reactor outlet pressure was changed to 65 kPaG, and the acrolein was used as the target product. The raw material conversion rate was 96.5%, and the acrolein yield was at most 85.2%. At this time, the reaction bath temperature was 334 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 420 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 385 ° C. In addition, the magnitude of the temperature of the two hot spots is related to the reversal when the conversion rate of the raw material is 95.5%. That is, Cmax-Ccrs = 1.0. The propylene conversion rate at the reaction bath temperature of 326 ° C was 94%, but the hot spot temperature of the catalyst layer on the gas inlet side was 347 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 415 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Example 6

A raw material gas inlet side of a stainless steel reactor having an inner diameter of 27.2 mm, which is a jacket for circulating a molten salt of a heat medium and a thermocouple for measuring the temperature of the catalyst layer, is provided on the tube shaft, and the diameter is sequentially filled. 5.2 mm cerium oxide-alumina sphere 20 cm, as the oxidation catalyst first layer (raw material gas inlet side), the oxidation catalyst (F1) and the 5.2 mm diameter cerium oxide-alumina mixture inert carrier by weight ratio The diluted catalyst was mixed at 3:1 to 100 cm, and the oxidation catalyst (F3) as the oxidation catalyst second layer (gas outlet side) was 210 cm, and the reaction bath temperature was set to 325 °C. Here, the gas in which the supply amount of propylene, air, nitrogen, and water is set to be oxidized at a space velocity of 1,250 h ^-1 by using a raw material molar ratio of propylene: oxygen: nitrogen: water = 1:1.7:8.8:1. The reactor outlet pressure was set to 50 kPaG, and the reaction bath temperature was changed in units of 2 ° C over 200 hours after the start of the reaction, and the reaction temperature change test was carried out. As a result, the raw material conversion rate was 97.8%, and acrolein and acrylic acid were used. The total yield was 91.5%. At this time, the reaction bath temperature was 322 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 424 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 373 ° C. In addition, the magnitude of the temperature of the two hot spots is related to the reversal when the conversion rate of the raw material is 96.6%. That is, Cmax-Ccrs = 1.2. The propylene conversion rate at the reaction bath temperature of 310 ° C was 92%, but the hot spot temperature of the catalyst layer on the gas inlet side was 330 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 400 ° C. Thus, even when the propylene conversion rate is greatly lowered, the temperature of the catalyst layer hot spot on the gas outlet side is not extremely increased, suggesting that it can operate stably for a long period of time.

Comparative example 1

In the oxidation reaction condition of the first embodiment, the catalyst filled in the inlet portion of the raw material gas is set as a dilution contact of F3 and a 5.2 mm diameter ceria-alumina mixture inert carrier at a weight ratio of 2:1. The oxidation reaction of propylene was carried out in the same manner as in Example 1 except that the catalyst filled in the outlet portion of the raw material gas was changed to 250 cm of the F3 catalyst. The reaction temperature change test was carried out, and as a result, the conversion of the raw material was 98.5%, and the total yield of acrolein and acrylic acid was 91.9% at the maximum. At this time, the reaction bath temperature was 335 ° C, the hot spot temperature of the catalyst layer on the gas inlet side was 418 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 380 ° C. In addition, the magnitude of the temperature of the two hot spots is inversely related to the conversion of the raw material of 98.2%. That is, Cmax-Ccrs = 0.3. The propylene conversion rate at the reaction bath temperature of 326 ° C was 95.5%, the hot spot temperature of the catalyst layer on the gas inlet side was 358 ° C, and the hot spot temperature of the catalyst layer on the gas outlet side was 445 ° C. When the propylene conversion rate is greatly lowered as compared with the examples, the temperature of the catalyst layer hot spot on the gas outlet side is extremely high.

The present invention has been described in detail above with reference to the specific embodiments thereof. It is understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

In addition, the present application is based on a Japanese patent application filed on Jul. 20, 2012 (Japanese Patent Application No. 2012-161353). In addition, all references cited in the present application are hereby incorporated by reference in their entirety.

[Industrial availability]

According to the present invention, acrolein and acrylic acid can be produced safely and stably in high yield. Or methacrolein and methacrylic acid.

Claims (6)

A method for producing acrolein and acrylic acid, or methacrolein and methacrylic acid, which uses a fixed bed multitubular reactor, using a gas containing molecular oxygen to propylene, or selected from isobutylene and tertiary butanol At least one of the methods for producing acrolein, acrylic acid, or methacrolein and methacrylic acid by a vapor phase contact oxidation, and A) is provided to be divided into N layers (N is 2 or more) along the flow direction of the material gas in the reaction tube. The multilayer catalyst layer formed by the integer is such that the catalyst layer closest to the reaction gas inlet side of the catalyst layer is Zin, the catalyst layer closest to the reaction gas outlet side is Zout, and B) is filled in the following manner. Catalyst: The activity of the catalyst filled in Zout is higher than the activity of the catalyst filled in Zin, so that the following formula (1) is satisfied: 0.5 ≦ Cmax-Ccrs (1) Cmax: the maximum yield of the target product is obtained. Conversion rate; Ccrs: The maximum temperature of the catalyst layer Zin is set to Tin, and the maximum temperature of the catalyst layer Zout is set to Tout. When the conversion rate of the raw material is changed, the relationship between the size of Tin and Tout is reversed. A method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to the first aspect of the patent application, wherein 0.5 ≦Cmax-Ccrs≦10 is satisfied. A method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to the first aspect of the invention, wherein 0.5≦Cmax-Ccrs≦5 is satisfied. The method for producing acrolein, acrylic acid, or methacrolein or methacrylic acid according to any one of claims 1 to 3, wherein N is 3 or less, and firing of a catalyst filled with Zin The temperature is higher than the firing temperature of the catalyst filled in Zout, and further the Zin is filled with a mixture of the catalyst and the inert material molded body. The method for producing acrolein, acrylic acid, or methacrolein and methacrylic acid according to any one of claims 1 to 4, wherein the catalyst is used to carry the active powder to the inert substance. The ball is loaded with a catalyst. The method for producing acrolein, acrylic acid, or methacrolein and methacrylic acid according to any one of claims 1 to 5, wherein the particle size of the catalyst filled in each catalyst layer is in the entire layer. It is uniform.