TWI429483B - Process for producing catalyst for use in producing unsaturated aldehyde and unsaturated carboxylic acid, and process for producing unsaturated aldehyde and unsaturated carboxylic acid - Google Patents

Description

Method for producing a catalyst for preparing unsaturated aldehydes and unsaturated carboxylic acids, and method for preparing unsaturated aldehydes and unsaturated carboxylic acids

This invention relates to a process for the preparation of a catalyst for the preparation of unsaturated aldehydes and unsaturated carboxylic acids. Further, the present invention relates to a process for producing an unsaturated aldehyde and an unsaturated carboxylic acid using the catalyst obtained by the above process.

It has long been known to use a molecular oxygen to catalytically oxidize propylene to produce a catalyst for acrolein and acrylic acid, or to use molecular oxygen in the gas phase to catalytically oxidize isobutylene or tert-butanol to produce methacrolein. The catalyst used for methacrylic acid is effectively used as a catalyst comprising a mixed oxide of molybdenum, niobium and iron. These catalysts for preparing unsaturated aldehydes and unsaturated carboxylic acids are usually prepared by drying an aqueous solution or a water slurry obtained by mixing a raw material in water, and finally calcining the obtained catalyst precursor. The calcination is usually carried out in a gas atmosphere containing molecular oxygen such as an air, as in, for example, JP-A 62-234548, JP-A-4-4048, JP-A-7-114473, JP-A-2000. -70719 and those disclosed in JP-A-2004-351295.

However, catalysts for the preparation of unsaturated aldehydes and unsaturated carboxylic acids according to conventional methods have insufficient catalytic activity, and thus, propylene, isobutylene and tert-butanol may not be oxidized at a good conversion rate, and Satisfactory yields give the corresponding unsaturated aldehydes and unsaturated carboxylic acids. When the reaction temperature is raised to increase the conversion rate, side reactions such as successive oxidations are easily carried out, and the unsaturated aldehyde may not be obtained in a satisfactory yield. With unsaturated carboxylic acids.

Accordingly, it is an object of the present invention to provide a process for producing a catalyst for use in the production of unsaturated aldehydes and unsaturated carboxylic acids having excellent catalytic activity. Further, it is an object of the present invention to provide a process for producing a corresponding unsaturated aldehyde in a good yield by oxidizing propylene, isobutylene or a third alcohol at a good conversion rate using a catalyst obtained by the above method. With unsaturated carboxylic acids.

Summary of invention

The present invention provides a method for producing a catalyst for catalytically oxidizing a compound selected from the group consisting of propylene, isobutylene and tert-butanol by molecular oxygen in the gas phase to prepare an unsaturated aldehyde and an unsaturated group. A carboxylic acid comprising a mixed oxide containing molybdenum, niobium and iron, wherein the catalyst is calcined in a gaseous environment containing molecular oxygen; and then heat-treated in the presence of a reducing substance.

Further, the present invention provides a process for producing an unsaturated aldehyde and an unsaturated carboxylic acid, which comprises the steps of: producing a catalyst by the above method, and then subjecting a compound selected from the group consisting of propylene, isobutylene and tert-butanol to gas In the phase, molecular oxygen is used for catalytic oxidation in the presence of the catalyst.

According to the present invention, a catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid having excellent catalytic activity can be produced. In addition, by using the catalyst thus obtained, propylene, isobutylene and the first can be used under good conversion. Tributanol is oxidized to produce the corresponding unsaturated aldehyde and unsaturated carboxylic acid in good yield.

Detailed description of the invention

The invention will be described in detail below. In the present invention, the catalyst for the preparation of the unsaturated aldehyde and the unsaturated carboxylic acid includes a mixed oxide containing molybdenum, ruthenium and iron as essential components. The mixed oxide may contain elements other than molybdenum, niobium and iron, preferably nickel and/or cobalt, and an element selected from the group consisting of potassium, rubidium, cesium and strontium.

A preferred mixture oxide can be exemplified by the following general formula (1): Mo _a Bi _b Fe _c A _d B _e C _f D _g O _x (1) wherein Mo, Bi and Fe are molybdenum, niobium and iron, respectively; Nickel and/or cobalt; B is an element selected from the group consisting of manganese, zinc, calcium, magnesium, tin and lead; and C is selected from the group consisting of phosphorus, boron, arsenic, antimony, tungsten, antimony, bismuth, aluminum, titanium, zirconium An element in the 铈; D is an element selected from the group consisting of potassium, strontium, barium, and strontium; when a = 12, 0 < b 10,0<c 10,1 d 10,0 e 10,0 f 10, and 0<g 2; and x is a value depending on the oxidation state of each element.

Among them, it is preferred to use a compound having the following composition (exemplified by no oxygen atom).

Mo _a Bi _b Fe _c Co _d CS _g (a=12, 0.1 b 5,0.5 c 5,5 d 10,0.01 g 1)

Mo _a Bi _b Fe _c Co _d Sb _f K _g (a=12, 0.1 b 5,0.5 c 5,5 d 10,0.1 f 5,0.01 g 1)

Mo _a Bi _b Fe _c Ni _d Sb _f1 Si _f2 Tl _g (a=12,0.1 b 5,0.5 c 5,5 d 10,0.1 F1 5,0.1 F2 5,0.01 g 1)

As a raw material of the above catalyst, a compound containing each element contained in a catalyst such as an oxide, a nitrate, a sulfate, a carbonate, a hydroxide, an oxyacid, and the like is used in a ratio satisfying a specified atomic ratio. Ammonium salts, and halides. For example, regarding the molybdenum compound, molybdenum trioxide, molybdic acid, ammonium molybdate, and the like may be used; as the antimony compound, cerium oxide, cerium nitrate, cerium sulfate, and the like may be used; and as the iron compound, iron nitrate may be used (for example); III), iron (III) sulfate, iron (III) chloride and the like.

In the method for producing a catalyst according to the present invention, a catalyst precursor prepared from the above raw material is calcined in a gas atmosphere containing molecular oxygen, and then heat-treated in the presence of a reducing substance. The catalyst precursor can generally be prepared by mixing the feedstock in water to produce an aqueous or aqueous slurry which is then dried by drying the aqueous solution or water slurry. The solution or slurry can be dried using, for example, a kneader, a box dryer, a barrel type flow drying device, a spray dryer, a flash dryer, and the like.

The catalyst precursor thus obtained is calcined in a molecular oxygen-containing gas atmosphere. The concentration of molecular oxygen in this gas is usually from 1 to 30% by volume, preferably from 10 to 25% by volume. Regarding the source of molecular oxygen, air or pure oxygen is often used, and if necessary, it is used after being diluted with nitrogen, carbon dioxide, water, helium, argon, and the like, and the gas thus obtained is utilized as a molecular oxygen-containing gas. . The calcination temperature is usually from 300 to 600 ° C, preferably from 400 to 550 ° C. The calcination time is usually from 5 minutes to 40 hours, preferably from 1 hour to 20 hours.

In the present invention, the calcined catalyst precursor obtained in the above calcination is heat-treated in a reducing substance (this treatment is sometimes referred to as a reduction treatment hereinafter). This reduction treatment can effectively improve the activity of the catalyst.

Examples of the reducing substance include, for example, hydrogen, ammonia, carbon monoxide, hydrocarbons, alcohols, aldehydes, amines, and the like. These can be used in combination as needed. Preferably, the hydrocarbons, alcohols, aldehydes and amines each have from about 1 to about 6 carbon atoms. Examples of the hydrocarbon may include saturated aliphatic hydrocarbons such as methane, ethane, propane, n-butane, and isobutane; unsaturated aliphatic hydrocarbons such as ethylene, propylene, α-butene, β-butene, and isobutylene; benzene, and Similar. Examples of the alcohol may include saturated aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, second butanol, and third butanol; unsaturated aliphatic alcohols such as allyl alcohol , crotyl alcohol, and methyl allyl alcohol; phenol, and the like. Examples of the aldehyde may include saturated aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, and isobutyraldehyde; unsaturated aliphatic aldehydes such as acrolein, crotonaldehyde, and methacrolein, and the like. Examples of the amine may include saturated aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, and triethylamine; unsaturated aliphatic amines such as allylamine and di-allylamine; aniline, and Similar.

This reduction treatment is usually carried out by heat-treating the calcined catalyst precursor in a gas atmosphere containing the above-mentioned reducing substance. The concentration of the reducing substance in the gas is usually from 0.1 to 50% by volume, preferably from 1 to 50% by volume, more preferably from 3 to 30% by volume. The reducing substance may be diluted with nitrogen, carbon dioxide, water, helium, argon, or the like to have the above concentration. The gas may contain molecular oxygen in a range that does not impair the effectiveness of the reduction treatment, but is generally preferably free of molecular oxygen.

The reduction treatment temperature is usually from 200 to 600 ° C, preferably from 300 to 500 ° C. The reduction treatment time is usually from 5 minutes to 20 hours, preferably from 30 minutes to 10 hours. Preferably, the reduction treatment is carried out by passing the calcined catalyst precursor to a vessel such as a tubular vessel or a tank vessel, and passing a gas containing a reducing substance therethrough. In this case, the exhaust gas from the vessel can be recycled as needed. For example, the calcined catalyst precursor is filled in a reaction tube for gaseous catalytic oxidation, and an oxygen containing a reducing substance is passed therethrough to carry out a reduction treatment, after which gas phase catalytic oxidation can be carried out.

Generally, the mass of the catalyst is reduced after the reduction treatment, which may be caused by the loss of lattice oxygen from the calcined catalyst precursor. The mass loss rate is preferably from 0.05 to 6%, more preferably from 0.1 to 5%. Catalytic activity may be reduced when excessive reduction occurs and the mass loss rate is too high. In this case, it is preferred to carry out calcination in a gas atmosphere containing molecular oxygen to reduce the mass loss rate. The mass loss rate is calculated from the equation below.

Mass loss rate (%) = [(mass of calcined catalyst precursor before reduction treatment - catalyst mass after reduction treatment) / quality of calcined catalyst precursor before reduction treatment] × 100

When the reduction treatment is carried out, after the treatment, the reducing substance itself and its decomposition product may be retained in the catalyst depending on the type of the reducing substance used and the heat treatment conditions. In this case, the mass of the residual product in the catalyst is measured individually, and the value obtained by subtracting the mass of the catalyst containing the residual product after the reduction treatment is taken as the mass of the catalyst after the treatment. Since the residual product is typically carbon, its mass can be measured, for example, by total carbon (TC) measurements and the like.

The catalyst is typically used after being formed into the desired shape. Preferably, they are formed into rings, pellets, balls, and the like via tableting or extrusion molding. This formation can be carried out in a catalyst precursor state before calcination in a molecular oxygen-containing gas atmosphere, and can be carried out after calcination or after reduction treatment. In the formation, in order to improve the mechanical strength of the catalyst, inorganic fibers which are substantially inert to the oxidation reaction and the like may be added, as described in JP-A-9-52053.

The catalyst thus obtained for producing an unsaturated aldehyde and an unsaturated carboxylic acid has excellent catalytic activity. By using the catalyst, propylene can be catalytically oxidized in the gas phase with molecular oxygen to produce acrolein and acrylic acid in good yield. Further, via the use of the catalyst, it is possible to catalytically oxidize isobutylene or tert-butanol in the gas phase with molecular oxygen to produce methacrolein and methacrylic acid in good yield.

According to the catalytic oxidation in the gas phase, the catalyst is usually filled into a fixed-bed multi-tubular reaction vessel, and then a starting gas containing molecular oxygen is supplied from the vessel and selected from the group consisting of propylene, isobutylene and tert-butanol. Starting compound. Fluid bed and moving bed reaction vessels can also be used. The source of molecular oxygen is typically air, and in addition to the starting compound and molecular oxygen, the starting gas may comprise nitrogen, carbon dioxide, carbon monoxide, steam, and the like.

The reaction temperature is usually from 250 to 400 ° C, and the reaction pressure is usually from 100 to 500 kPa, but the reaction can also be carried out under reduced pressure. The amount of molecular oxygen is often from 1 to 3 moles per mole of starting compound. The space velocity (SV) of the starting gas is often from 500 to 5,000 per hour based on STP (standard temperature and pressure).

Example

The following examples are illustrative of the invention, but the invention is not limited thereto. In the examples, the milliliter/minute indicating the gas flow rate is based on STP unless otherwise noted.

Comparative example 1

(a) Manufacture of catalyst

13,241 g of ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ ‧4H ₂ O] was dissolved in 15,000 g of warm water, which was referred to as liquid A. On the other hand, 6,060 g of iron(III) nitrate [Fe(NO ₃ ) ₃ ‧9H ₂ O], 13,096 g of cobalt nitrate [Co(NO ₃ ) ₂ ‧6H ₂ O] and 585 g of lanthanum nitrate [CsNO ₃ ] was dissolved in 6,000 g of warm water, and then, 2,910 g of bismuth nitrate [Bi(NO ₃ ) ₃ ‧5H ₂ O] was dissolved therein, which was referred to as liquid B. The liquid A was stirred, a liquid B was added thereto to obtain a slurry, and then the slurry was dried using a flash dryer to obtain a catalyst precursor. 6 parts by mass of the cerium oxide alumina fiber (ITMCo., Ltd., manufactured by RFMC (400-SL)) was added to 100 parts by mass of the catalyst precursor, and then formed to have an outer diameter of 6.3 mm. 2.5 mm inner diameter, and 6 mm length ring. The rings were calcined in a 516 ° C air stream for 6 hours to obtain a catalyst. The catalyst has 0.96 germanium atoms and 2.4 iron atoms per 12 molybdenum atoms. 7.2 cobalt atoms and 0.48 germanium atoms.

(b) Oxidation reaction

In a glass reaction tube having an inner diameter of 18 mm, 13 ml of the catalyst obtained in the step (a) was filled, and a mixture of isobutylene/oxygen/nitrogen/steam=1/2.2/6.7/2.1 (mole ratio) was mixed. When the gas was supplied to the tube at a flow rate of 162.5 ml/min, an oxidation reaction was carried out at a reaction temperature of 360 °C. The conversion of isobutylene and the total yield of methacrolein and methacrylic acid are shown in Table 1.

Example 1

50 g of the catalyst obtained in Comparative Example 1 (a) was filled into a glass tube, and at the same time, a mixed gas of hydrogen/nitrogen = 10/90 (volume ratio) was supplied into the tube at a flow rate of 200 ml/min. The reduction treatment was carried out at 350 ° C for 5 hours. Then, the supply of hydrogen is stopped, followed by cooling under a stream of nitrogen The reduced catalyst was obtained at room temperature. The mass loss rate of the catalyst after reduction treatment was 0.84%.

The same oxidation reaction in Comparative Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 320 °C. Table 1 shows the results obtained.

Example 2

The same procedure as in Example 1 was carried out, except that the gas used in the reduction treatment was changed to a mixed gas of hydrogen/nitrogen=20/80 (volume ratio), the reduction treatment temperature was changed to 400 ° C, and the reduction treatment time was changed. The reduced catalyst was obtained for 3 hours. The mass loss rate of the catalyst after reduction treatment was 3.52%.

The same oxidation reaction in Comparative Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 320 °C. Table 1 shows the results obtained.

Example 3

The same procedure as in Example 1 was carried out, except that the gas used in the reduction treatment was changed to a mixed gas of hydrogen/nitrogen=20/80 (volume ratio), and the reduction treatment temperature was changed to 400 ° C to obtain a reduction treatment. Catalyst. The mass loss rate of the catalyst after reduction treatment was 6.42%.

Then, the temperature was increased to 200 ° C under a nitrogen flow of 200 ml / minute, and while the air was intermittently supplied at 200 ml / minute, the temperature was further raised to 400 ° C within 8 hours, and the temperature was maintained under air flow. After holding at 400 ° C for 1 hour, it was cooled to room temperature to obtain an air-calcined reduced-treating catalyst. The total mass loss rate of the catalyst caused by the loss rate after the reduction treatment plus the loss rate after air calcination was 0.36%.

The same oxidation reaction in Comparative Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 320 °C. Table 1 shows the results obtained.

Example 4

25 g of the catalyst obtained in Comparative Example 1 (a) was filled into a glass tube, and at the same time, a mixed gas of isobutylene/nitrogen/steam = 6.8/80.6/12.6 (volume ratio) was supplied at a flow rate of 600 ml/min. The reduction treatment was carried out at 366 ° C for 5 hours in the tube. Then, the supply of isobutylene and steam was stopped, followed by cooling to room temperature under a nitrogen stream to obtain a reduced-treated catalyst. The mass loss rate of the catalyst after reduction treatment was 1.18%.

The same oxidation reaction in Comparative Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 320 °C. Table 1 shows the results obtained.

Example 5

The same procedure as in Example 4 was carried out, except that ethanol was used in place of isobutylene to obtain a reduced catalyst. The mass loss rate of the catalyst after reduction treatment was 3.11%.

The same oxidation reaction in Comparative Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 300 °C. Table 1 shows The results obtained.

Example 6

25 g of the catalyst obtained in Comparative Example 1 (a) was filled into a glass tube, and at the same time, a mixed gas of methacrolein/nitrogen/steam = 4.3/78.2/17.5 (volume ratio) was 100 ml/min. The flow rate was supplied to the tube, and reduction treatment was carried out at 366 ° C for 2.5 hours. Then, the supply of methacrolein and steam was stopped, followed by cooling to room temperature under a nitrogen stream to obtain a reduced-treated catalyst. The mass loss rate of the catalyst after reduction treatment was 0.58%.

The same oxidation reaction as in Example 1 (b) was carried out except that the catalyst obtained above was used and the reaction temperature was changed to 320 °C. Table 1 shows the results obtained.

According to the present invention, the following invention is provided.

[1] A method for producing a catalyst for catalytically oxidizing a compound selected from the group consisting of propylene, isobutylene and third butanol by molecular oxygen in a gas phase to prepare an unsaturated aldehyde and an unsaturated carboxylic acid The acid contains a mixed oxide containing molybdenum, niobium and iron, wherein the catalyst is calcined in a gaseous environment containing molecular oxygen; and then heat-treated in the presence of a reducing substance.

[2] The method according to [1], wherein the mixed oxide is represented by the following general formula (1): Mo _a Bi _b Fe _c A _d B _e C _f D _g O _x (1) wherein Mo, Bi And Fe are molybdenum, niobium and iron respectively; A is nickel and/or cobalt; B is an element selected from the group consisting of manganese, zinc, calcium, magnesium, tin and lead; and C is selected from the group consisting of phosphorus, boron, arsenic and antimony. An element among tungsten, lanthanum, cerium, aluminum, titanium, zirconium and hafnium; D is an element selected from the group consisting of potassium, lanthanum, cerium and lanthanum; when a = 12, 0 < b 10,0<c 10,1 d 10,0 e 10,0 f 10, and 0<g 2; and x is a value depending on the oxidation state of each element.

[3] The method according to [1] or [2], wherein the calcination system is carried out at 300 to 600 °C.

[4] The method according to any one of [1] to [3] wherein the heat treatment is carried out at 200 to 600 °C.

[5] The method according to any one of [1] to [4] wherein the mass loss rate by the heat treatment is 0.05 to 6% by mass.

[6] The method according to any one of [1] to [5] wherein the reducing substance is a compound selected from the group consisting of hydrogen, ammonia, carbon monoxide, a hydrocarbon having 1 to 6 carbon atoms, having 1 An alcohol having 6 carbon atoms, an aldehyde having 1 to 6 carbon atoms, and an amine having 1 to 6 carbon atoms.

[7] A method for producing an unsaturated aldehyde and an unsaturated carboxylic acid, the method comprising the steps of: producing a catalyst by the method of any one of [1] to [6], and then selecting a catalyst selected from the group consisting of propylene, isobutylene, and The compound in the third butanol is catalytically oxidized in the gas phase using molecular oxygen in the presence of the catalyst.

Claims (5)

A method for producing a catalyst for catalytically oxidizing a compound selected from the group consisting of propylene, isobutylene and tert-butanol in a gas phase by molecular oxygen to prepare an unsaturated aldehyde and an unsaturated carboxylic acid, The catalyst comprises a mixed oxide containing molybdenum, niobium and iron, wherein the catalyst is calcined under a gaseous environment containing molecular oxygen; and then the gas containing the reducing substance is passed through the vessel and heat treated together. Wherein the mixed oxide is represented by the following general formula (1): Mo _a Bi _b Fe _c A _d B _e C _f D _g O _x (1) wherein Mo, Bi and Fe are molybdenum, niobium and iron, respectively; A is nickel and/or cobalt; B is an element selected from the group consisting of manganese, zinc, calcium, magnesium, tin and lead; and C is selected from the group consisting of phosphorus, boron, arsenic, antimony, tungsten, antimony, bismuth, aluminum, titanium, An element among zirconium and hafnium; D is an element selected from the group consisting of potassium, rubidium, cesium and strontium; when a=12, 0<b 10,0<c 10,1 d 10,0 e 10,0 f 10, and 0<g 2; and x is a value depending on the oxidation state of each element, and wherein the reducing substance is a compound selected from the group consisting of hydrogen, ammonia, carbon monoxide, a hydrocarbon having 1 to 6 carbon atoms, having 1 to An alcohol having 6 carbon atoms, an aldehyde having 1 to 6 carbon atoms, and an amine having 1 to 6 carbon atoms. The method of claim 1, wherein the calcination is carried out at 300 to 600 °C. The method of claim 1, wherein the heat treatment is carried out at 200 to 600 °C. The method of claim 1, wherein the mass loss rate by the heat treatment is 0.05 to 6% by mass. A process for producing an unsaturated aldehyde and an unsaturated carboxylic acid, the process comprising the steps of: producing a catalyst by a method according to any one of claims 1 to 4, and then selecting a catalyst selected from the group consisting of propylene, isobutylene and The compound in the third butanol is catalytically oxidized in the gas phase using molecular oxygen in the presence of the catalyst.