JPS6012134A - Preparation of catalyst for preparing unsaturated acid - Google Patents

Abstract

PURPOSE:To obtain the titled catalyst capable of preparing an unsaturated acid such as (meth)acrylic acid in high yield, by a method wherein compounds containing P and Mo being catalyst componential elements are mixed in the presence of water to form a solution mixture or a slurry and, after drying, the obtained solid substance is ground in the presence of aromatic hydrocarbon before molding. CONSTITUTION:In preparing an unsaturated acid such as (meth)acrylic acid from (meth)acrolein by using a hetero-polyacid system containing P and Mo as catalyst components, the aforementioned catalyst is prepared according to the following method. That is a compound containing prescribed amounts of catalyst componential elements (e.g., MoO3, H3PO4 or the like) are mixed in the presence of water to prepare a solution mixture or a slurry. In mixing, a temp. is generally 20-80 deg.C and ageing is desirably performed at 50-90 deg.C for 1-20hr after mixing. In the next step, the aforementioned solution mixture or slurry is dried to obtain a solid substance which is, in turn, ground in the presence of an aromatic compound represented by formula (wherein R is a lower alkyl group and n is 0, 1, 2 or 3) (e.g., benzene) to form particles with a particle size of 15mum or less and the aromatic compound is pref. removed to mold said particles. The obtained molded substance is dried at 50-150 deg.C if necessary to be used as the aforementioned catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a heteropolyacid-based unsaturated acid containing phosphorus and molybdenum as catalyst component elements, which can produce unsaturated acids such as acrylic acid and methacrylic acid in high yield. This paper relates to a new method for producing catalysts.

A method for producing acrylic acid or methacrylic acid by reacting acrolein or methacrolein with molecular oxygen in a high temperature gas phase in the presence of a heteropolyacid catalyst containing phosphorus and molybdenum as catalyst component elements is already known. Heteropolyacid catalysts generally use a compound containing catalytic elements as a starting material, add a carrier if necessary, mix these in the presence of water, etc., form a solution or slurry, and dry this. , generally evaporated to dryness.

It is manufactured by molding or firing as required without molding (Japanese Patent Application Laid-Open No. 55-1, 24734, JP-A No. 55-31006, etc.).

It also commonly contains phosphorus and molybdenum (peteropolyacid)
or its salts) as a skeletal structure.
n) Structure (central element phosphorus, arsenic, etc.)

Coordination elements molybdenum, tungsten, vanadium, etc.)
It is said that the skeleton is surrounded by protons or cations and water of crystallization, and the crystal water of heteropolyacids ranges from 1 to 30 molecules, depending on the temperature, and at room temperature there are 10 to 30 molecules. in the range of 100
At temperatures above ℃, the number of molecules is less than 5.

The present inventors have conducted intensive research on the production of unsaturated acids such as acrylic acid and methacrylic acid using heteropolyacid catalysts containing phosphorus and molybdenum as catalyst components. The inventors discovered that an unsaturated acid can be produced at a lower reaction temperature and in a higher yield than when using a catalyst obtained by a conventional method for producing a heteropolyacid catalyst, leading to the present invention.

The present invention relates to a heteropolyacid-based compound containing phosphorus and molybdenum as catalyst component elements, which is used to produce acrylic acid or methacrylic acid by reacting acrolein or methacrolein with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. In a method for producing a catalyst for producing an unsaturated acid, a mixed solution or slurry obtained by mixing compounds containing catalyst component elements in the presence of water is dried, and the resulting solid is produced by formula.

(In the formula, R represents a lower alkyl group, and n is 0, 1°2 or di.) Production of an unsaturated acid characterized by pulverization in the presence of an aromatic hydrocarbon represented by the formula and then molding. The present invention relates to a method for producing a catalyst for use in the present invention.

According to the present invention, when a solid is pulverized in the presence of an aromatic compound represented by formula (1), the activity of the resulting catalyst and the selectivity to the target product can be further increased, and (1)
At relatively low reaction temperatures and (2) short contact times, (8
) A catalyst is obtained that can produce the target unsaturated acids such as acrylic acid and methacrylic acid in high yield over a long period of time.

The present invention can be widely applied to the production of heteropolyacid-based catalysts for the production of unsaturated acids containing phosphorus and molybdenum as catalyst component elements. tungsten,
Iron, bismuth, antimony, cobalt, arsenic, zirconium.

Calcium, chromium, boron, tin, titanium, copper.

Germanium, tantalum, cerium, vanadium.

Magnesium, silver, aluminum, tellurium, potassium,
Strontium, barium, indium.

It can be applied to the production of catalysts containing cesium, rubidium, niobium, lead, etc. as catalyst component elements.

In the present invention, a heteropolyacid-based catalyst for producing an unsaturated acid containing phosphorus and molybdenum can be represented by the following general formula.

Mo1□PaXbOxHy... (2) IM in the formula
O stands for molybdenum, P stands for phosphorus, 0 stands for oxygen, H stands for hydrogen, and X stands for the element conventionally contained in this type of catalyst, and the subscript indicates the number of atoms.

a is 0.5-2, preferably 0.8-1.2.1) is 0-4°, preferably 0.5-2, and X is 10-50. y
is 1-5.

In the present invention, first, a compound containing a predetermined amount of catalyst component elements is mixed in the presence of water to prepare a mixed solution or slurry. Typical compounds containing catalyst component elements used as starting materials include molybdenum trioxide, molybdic acid, phosphomolybdic acid, phosphoric acid, as well as oxides and salts of the above-mentioned X component elements. be able to. The order of mixing the compounds containing catalyst component elements is not particularly limited. The appropriate mixing temperature is generally 20 to 80°C, and if the mixture is sufficiently uniform,
There is no particular restriction on the mixing time, but after mixing it is
It is desirable to age for ~20 hours. Aging is generally carried out under an air atmosphere.

Further, it is preferable to add an organic reducing substance to a mixed solution or slurry, since this improves the performance of the resulting catalyst. The amount of the organic reducing substance to be used varies depending on the type of the organic reducing substance used, but the appropriate amount is 0.5 to 10% by weight based on the resulting catalyst. If the amount of the organic reducing substance used is too large or too small, the effect of its addition will be negligible. As the organic reducing substance, generally known organic substances having reducing properties can be used, and a typical example thereof is stearic acid.

palmitic acid, glyoxylic acid, lactic acid, glycolic acid,
Examples include polyvinyl alcohol, polyvinylpyrrolidone, gum arabic, starch, ethylene glycol, propylene glycol, polyalkylene glycol, textrin, aldose, and fulldose. There is no significant difference in the catalytic performance of the resulting catalyst whether one type or multiple types of organic reducing substances are used.

In the present invention, a mixed solution or slurry obtained by mixing a compound containing a catalyst component element in the presence of water is dried to form a solid.The method for drying the mixed solution or slurry is known per se. Examples include evaporation to dryness method, spray drying method, rotary evaporator method, etc., but it is preferable to adjust the water content in the obtained solid material to 5 to 20% by weight. The above-mentioned water content may be adjusted after obtaining the solid material or from drying and drying, but after the water content is adjusted to the above-mentioned value.

Further aging is appropriate. Drying is generally carried out at 100 to 250°C under an air atmosphere.

In the present invention, the solid matter obtained by drying is expressed by the formula (1
) is important for further increasing the activity of the catalyst and the selectivity to the desired product.

Examples of the aromatic compound represented by formula (1) include benzene, toluene, xylene, hemimelitene, hydrocumene, and mesitylene.

Among these, benzene and toluene have low boiling points.

Xylene and the like are suitable. The amount of aromatic compound used is 10 to 80% by weight, preferably 20 to 80% by weight based on the solid matter.
A suitable amount is 70% by weight.

In addition, when crushing solid materials, make them into as fine a powder as possible.
It is preferable to pulverize the catalyst to a particle size of 15 #1 or less, more preferably 10 μm or less, and by pulverizing it into fine powder, the activity of the catalyst obtained can be made higher. Pulverizers used for grinding include ball mills, vibrating ball mills, and crushers.

Santo Klein Mill, Roll Mill, Ring Roller Mill, Raymond Mill, -, Attrition Mill.

There are no particular restrictions on the type, such as a rod mill.

Ball mills, crushers, ring roller mills, etc. are preferably used. Additionally, pulverization is generally done at room temperature.

It is convenient to perform this under normal pressure.

The pulverized product pulverized in the presence of the aromatic compound represented by formula (1) may be molded without removing the aromatic compound.Generally, the aromatic compound is pulverized by a method known per se 1, such as thermal evaporation. It is preferable to remove it by a method such as the following and then mold it. Further, during molding, a binder, a lubricant, etc. may be added or molded without addition. The amount of the binder, lubricant, etc. to be added varies depending on the properties of the pulverized material, the molding method, etc., but is generally about 1 to 30% by weight. Molding may be carried out by either a dry method or a wet method, and a tablet molding machine, an extrusion molding machine, etc. are generally conveniently used as the molding machine. The molded product is used after being dried (50 to 150°C) if necessary.

The reason why the activity of the catalyst obtained by the present invention and the selectivity to the target product are improved when a solid is pulverized in the presence of the aromatic compound represented by formula (1) is not yet fully clear; It is thought that this is because the specific surface area of the object increases, the average pore diameter becomes smaller when molded, the pore volume becomes larger, the number of active sites increases, and some of the heteropolyacid is still reduced. Ru.

In producing acrylic acid or methacrylic acid by reacting acrolein or methacrolein with molecular oxygen in the high temperature gas phase in the presence of the catalyst obtained according to the present invention,
The catalyst may be used together with a support. As the carrier, any of those conventionally known as carriers for catalysts for producing acrylic acid, methacrylic acid, etc. can be used, such as diatomaceous earth, alumina, silica, silica sol, and silicon carbide.

Graphite moth can be mentioned. In addition.

The carrier may be added at the time of catalyst production. The molecular oxygen used in the reaction may be pure oxygen gas, but it is not necessary to have particularly high purity, so it is generally economical and convenient to use air.

It is still advisable to use a diluent gas in the reaction together with molecular oxygen and acrolein or methacrolein. As the diluent gas, gases that have a negative effect on this reaction can be used, such as nitrogen, carbon dioxide gas, water vapor, etc. Among them, water vapor not only has the effect of improving the selectivity of acrylic acid or methacrylic acid, but also increases the catalytic activity. It is best to carry out the reaction in the presence of water vapor, as this has the effect of sustaining the reaction.

Furthermore, as with molecular oxygen, acrolein or methacrolein used in the reaction does not need to be of particularly high purity.9 For example, those obtained by oxidation reaction of propylene or imbutylene may be used as they are.

The catalyst obtained by this invention can be used in any reactor such as a fluidized bed, moving bed, or fixed bed reactor, but the catalyst obtained by this invention can be used for acrolein or It is generally advantageous to use a fixed bed reactor because it has the advantages of high methacrolein reaction rate and high acrylic acid or methacrylic acid selectivity, and the ability to maintain catalyst activity over a long period of time.

Further, the reaction may be carried out under normal pressure, increased pressure, reduced pressure, etc., but it is generally convenient to carry out the reaction under normal pressure. The reaction temperature is 200-400℃, preferably 250-6
50°C, especially 260-620°C is suitable. Further, the contact time is 0.1 to 10 seconds.

Preferably, O.S to 5 seconds is appropriate. For the reaction, it is preferable to use a mixed gas of acrolein or methacrolein and molecular oxygen, generally air, with water vapor added, and the composition of the mixed gas is 1 molecule per 1 mole of acrolein or methacrolein. Oxygen is 0.5-7
moles, preferably 1 to 5 moles, and water vapor of 0.5 to 60
mol, preferably 1 to 10 mol.

Further, to recover the desired product, acrylic acid or methacrylic acid, conventionally known methods such as condensation, solvent extraction, etc. are applied.

Next, Examples and Comparative Examples will be shown. Reaction rate (H) 1 in the example
Selectivity (%) and yield (%) follow the following definitions.

Example 1 Molybdenum trioxide (MOO3) 2409. 85 Tyrinic acid [: H3PO4] 16. Ot and 6.3 f of vanadium pentoxide [v2o5] were added to 1 t of distilled water heated to 50°C and dissolved with stirring. This solution was further heated to 80° C., aged for 20 hours with stirring, and then concentrated to dryness using a drum dryer to obtain a solid. The moisture content of this solid was measured and was found to be 12.1.
% by weight, and the solid was dried and aged in a dryer at 150°C. This dried solid (water content approximately 1.2% by weight) 10
0i 100 m of benzea and 3 g of stearic acid were placed in Bonylmil.

The slurry obtained by pulverization for 10 hours was taken out, and benzene was removed by evaporation to obtain a pulverized product (particle size: 2 to 10 μm). The pulverized product is made into 4 tpan l using a tablet molding machine.
X 4 ttan H was molded into pellets to obtain a catalyst. The atomic ratio of molybdenumyline to vanadium in the catalyst is 1
221:0.55.

Next, the catalyst 1011LI was placed in a U-shaped reaction tube made of heat-resistant glass with an inner diameter of 8 mm. , (15,8?) and nitrogen gas 1
00mA! ,/min, and then put it in a night bath maintained at 290°C while flowing 150 ml of a mixed gas of 5% methacrolein, 10% oxygen, 50% water vapor, and 55% nitrogen by volume instead of nitrogen gas! The contact reaction was carried out at a reaction temperature of 290° C. by supplying at a flow rate of /min. The contact time at that time was 4 seconds.

The results of the contact reaction (30 minutes after the start of the reaction) are shown in Table 1.

Comparative Example 1 The same as in Example 1 except that benzene and stearic acid were not used when the solid material was pulverized.

A catalyst was produced in the same manner as in Example 1, and a catalytic reaction of methacrolein was carried out under the same reaction conditions as in Example 1. The results of the contact reaction are shown in Table 1.

Table 1 Example 2 Molybdenum trioxide [MoO3] 240 f, 85% phosphoric acid (H2PO4) 16. Of, sodium pentoxide (Vans) 12.6, arsenic acid [H3AsO4]
(60% aqueous solution) 5B, 52, copper oxide ((!uo 〕4
．． 4 ft and 0.86 p of boric acid [H3BO3:] were added to 1.5 t of distilled water heated to 50°C and dissolved with stirring. This solution was stirred and aged at 80°C for 20 hours, and then concentrated and dried using a drum dryer to obtain a solid. The water content of this solid was 16.5% by weight. After drying and aging the solid in a dryer maintained at 150°C, the dried solid (moisture: 0.8% by weight) 200
? and xylene 2001114! ,! : PVP (polyhinylhyloritone polymerization degree of about 30,000) 51i' was placed in a ball mill.

After milling for about 20 hours, the resulting slurry was taken out of the ball mill and most of the xylene was removed by evaporation.
The pulverized material (particle size 2 to 10 μm) was processed using an extruder for 4Wr.
The catalyst was molded into pellets of 4 to 8 flll+l H. Catalyst Mo: P: V: As: Cu
: The atomic ratio of B was 12:1:1:0.2:0.420.1 The catalyst 10-(14.3t) was placed in a U-shaped reaction tube made of heat-resistant glass with an inner diameter of 8mm. Fill it with a mixed gas of water vapor and nitrogen (N
20:N2=1:5 molar ratio) to 100rIL4/
The reaction tube was placed in a night bath maintained at 280° C. while flowing at a flow rate of mln. Stop the flow operation of the mixed gas of water vapor and nitrogen, and the volume is 5 g of methacrolein and 10 g of oxygen.
fb, mixed gas of 30% water vapor and 55% nitrogen 400
mA! /min flow rate 2 reaction temperature 280℃
A contact reaction was carried out. The results of the contact reaction are shown in Table 2.

Examples 3 to 6 Catalysts having the compositions (atomic ratios) shown in Table 2 were produced in the same manner as in Example 2. However, in Example 6, chromium oxide [0r203] was used instead of boric acid, in Example 4, niobium oxide (Nbzos) was used instead of copper oxide, and in Example 5, boric acid was not used, and In Example 6, the catalyst was prepared without using arsenic acid.

Table 2 shows the results of a catalytic reaction of methacrolein under the same reaction conditions as in Example 2.

Comparative Example 2 A catalyst was produced in the same manner as in Example 2, except that xylene and polyvinylpyrrolidone were not used when pulverizing the solid material in Example 2.

A catalytic reaction of methacrolein was carried out under the same reaction conditions as in Example 2. The results of the contact reaction are shown in Table 2.

Table 2 Examples Example 7 12-Molybdophosphoric acid [H3PMo12040・29H
20) 200 t, 1.36 g of copper oxide [CuO], 10 g of a 60% aqueous solution of arsenic acid [H3AsO4'], and 0.6 BY of titanium oxide [TlO2] were dissolved and suspended in 1 t of water, and the mixture was heated at 50°C for 20 After aging with stirring for an hour, the mixture was concentrated under reduced pressure using a rotary evaporator. This concentrate was further dried for 5 hours in a dryer maintained at 150°C to mature and mature, to obtain a solid product (water content: about 0.9% by weight).

This solid 1001i',) luene 30- and PVA
(Polyvinyl alcohol, degree of polymerization about 1ooo) was placed in a crusher and crushed for 20 hours, then the slurry was taken out and toluene was removed by evaporation.

A pulverized product (particle size 5 to 10 μm) was obtained. The pulverized product was molded into pellets of 4 rtan91×4■H using a tablet molding machine to obtain a catalyst. Mo of the obtained catalyst: P: AEI
: The atomic ratio of Ou:Ti is 12:1:0.5:0.2
:0.1.

A heat-resistant glass U-shaped reaction tube with an inner diameter of 8 wml was filled with 10 ml (14.2 t) of catalyst, and 220 mJ of nitrogen gas was charged.
After the reaction tube was placed in a night bath kept at 270° C. while flowing nitrogen gas at 270° C., the flow of nitrogen gas was stopped.

A mixed gas containing 5% methacrolein, 10 g oxygen, 30 g water vapor, and 55 g nitrogen by volume was flowed at a flow rate of 400 mA'/min to carry out a catalytic reaction of methacrolein at a reaction temperature of 270°C. As a result of the catalytic reaction, the reaction rate of methacrolein was 94.5%, and the selectivity of methacrylic acid was 88.3%.
The yield of methacrylic acid was 85.4%.

Comparative Example 6 A catalyst was produced in the same manner as in Example 7, except that the solid material in Example 7 was pulverized without using toluene and polyvinyl alcohol.

A catalytic reaction of methacrolein was carried out under the same reaction conditions as in Example 2. As a result of the catalytic reaction, the reaction rate of methacrolein was 89.6%, the selectivity of methacrylic acid was 87.5%, and the yield of methacrylic acid was 78.4%.Example 8 Using the same catalyst as in Example 1 at 10 mA ' was filled into a heat-resistant glass U-shaped reaction tube with an inner diameter of 8W+11, and nitrogen gas was heated at 220W.
After placing the reaction tube in a night bath kept at 280 °C while flowing Le/min, the flow of nitrogen gas was stopped and the reactor was heated with 6% acrolein, 10% oxygen, 0 ml of water vapor filter, and 54 ml of nitrogen by volume. Mixed gas 400me/min
The contact reaction was carried out at a temperature of 280°C. As a result, the reaction rate of acrolein was 95i1%, the selectivity of acrylic acid was 94.0%, and the yield of acrylic acid was 89.
It was 4%.

Patent applicant: Ube Industries Co., Ltd.

Claims (1)

[Scope of Claims] A heteropolyacid containing phosphorus and molybdenum as catalyst component elements used for producing acrylic acid or methacrylic acid by reacting acrolein or methacrolein with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. In a method for producing a catalyst for producing an unsaturated acid based on the formula, a mixed solution or slug IJ-, in which compounds containing catalyst component elements are mixed in the presence of water, is dried, and the resulting solid is expressed by the formula: (In the formula, R represents a lower alkyl group, and n is 0, 1°2 or O). Method for producing catalysts for use.