JPS5913256B2 - Method for producing catalyst for producing maleic anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a catalyst for producing maleic anhydride.

Specifically, the present invention relates to a method for producing a phosphorus-vanadium-iron-oxygen catalyst used for producing maleic anhydride by catalytically oxidizing an unsaturated hydrocarbon having 4 or more carbon atoms in a gas phase. be. Conventionally, a phosphorus-vanadium-oxygen catalyst is known as a typical catalyst for producing maleic anhydride by catalytically oxidizing an unsaturated hydrocarbon having 4 or more carbon atoms in a gas phase.

However, this type of catalyst produces maleic anhydride with a good yield when the raw material unsaturated hydrocarbon concentration in the feed gas is low, but as the raw material unsaturated hydrocarbon concentration increases, maleic anhydride increases. The acid yield tends to decrease.

As a result of extensive research into catalysts that can produce maleic anhydride in good yields even from highly concentrated unsaturated hydrocarbons, the present inventors discovered that phosphorus-vanadium with a specific composition obtained by a specific production method -The present invention was achieved by discovering that by using an iron-oxygen catalyst, maleic anhydride can be produced with a good yield even when the concentration of raw material unsaturated hydrocarbons in the feed gas is high. did.

That is, an object of the present invention is to provide a catalyst that can industrially advantageously produce maleic anhydride in good yield not only from low concentration but also from high concentration unsaturated hydrocarbons.

Therefore, this objective can be easily achieved by drying an aqueous solution of a vanadium compound, a phosphorus compound, and an iron chloride as it is or after mixing with a carrier, and then calcining the solution at a temperature of 200 to 700°C.

5 To explain the present invention in more detail, the main components of the catalyst produced by the method of the present invention are phosphorus, vanadium, and iron.

The vanadium compounds used in this catalyst preparation include:
Usually vanadium pentoxide, vanadyl salts such as ammonium vanadate, and other pentavalent vanadium compounds are used.

When using these pentavalent vanadium compounds,
It is preferred that a reducing substance such as hydrochloric acid or oxalic acid be present during the preparation process of the catalyst to reduce the valence to a valence lower than pentavalence. 3
5. It is also possible to use a compound having a valence lower than pentavalence, such as vanadyl oxalate, and in that case, it is not necessary to coexist with the above-mentioned reducing substance.

Examples of phosphorus compounds include various phosphorus acids such as phosphorus pentoxide, metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, and phosphorous acid, or salts thereof, such as ammonium phosphates, or organic phosphorus compounds such as trimethyl phosphate. is used.
Further, as the iron compound, iron chlorides such as ferrous chloride and ferric chloride are used. To prepare a catalyst from these vanadium-phosphorus- and iron-compounds, the atomic percentages of vanadium, phosphorus, and iron in the catalyst are from 1 to 32% vanadium,
The above compounds are used in proportions of 47-80% phosphorus and 4-50% iron, preferably 2-30% vanadium, 50-75% phosphorus and 5-47% iron.

However, if the atomic percentage of each component of the catalyst exceeds the above range, for example if vanadium is less than 1%, a catalyst with sufficient activity cannot be obtained.

On the other hand, when vanadium exceeds 32%, the activity of the catalyst decreases. The same percentage for phosphorus is 47? If the amount is less, a catalyst with sufficient activity cannot be obtained.

Furthermore, if the phosphorus content exceeds 80%, the optimum temperature for the reaction becomes too high and the activity of the catalyst decreases, making it impractical. Furthermore, when the proportion of iron is less than 4%, the catalyst activity cannot be sufficiently improved, and when it exceeds 50%, the activity of the catalyst is rather reduced. The catalyst of the present invention is prepared by dissolving a vanadium compound, a phosphorus compound, and an iron compound in water, then drying the solution as it is or mixing it with a carrier, and then calcining it.

As an example of the preparation method, first, a pentavalent vanadium compound such as vanadium pentoxide or ammonium vanadate is suspended in water, a reducing substance such as oxalic acid is added thereto, and the temperature is 50 to 100°C, preferably. Vanadium is reduced by heating at 80-90°C for about 30 minutes, and a phosphorus compound such as phosphoric acid, ammonium phosphate or phosphorus pentoxide is added to the resulting solution, and then iron chloride is added to this solution to make a homogeneous solution. The catalyst solid obtained by heating and stirring and evaporating to dryness, or by spray drying, is molded if necessary and calcined at a temperature of 200 to 700°C, preferably 300 to 650°C. Of course, a phosphorus compound is added to a reduced solution of a vanadium compound obtained by a reduction method other than the above method, and then iron chloride is added to this solution to make a homogeneous solution, and then heated and stirred to evaporate to dryness or spray-dried. The catalyst solid obtained by the process is calcined at the above temperature, or the three components of vanadium compound, phosphorus compound and iron chloride are mixed, and this mixture is then treated with a reducing substance such as oxalic acid to form a solution. The same processing as above may be performed.

Therefore, it is usually preferable to use these catalysts by supporting them on a carrier, and examples of the carrier include alumina, silica, titania, silica-titania, aluminum phosphate, diatomaceous earth, silicon carbide, and the like. Use commonly used carriers.

Among these carriers, silica and titania are preferably used in combination. The amount of catalyst components supported varies depending on the carrier used, the manufacturing method of the catalyst, and the form of use, but is usually .
3 weight based on the total amount of catalyst? The above ratio is preferably 10% by weight or more, more preferably 20 to 60% by weight. The catalyst is supported on the carrier by a conventional method.

For example, evaporation to dryness method, immersion method, spray drying method, etc. are employed. In the spray drying method, a solution in which a catalyst component is dissolved and a powder or colloidal carrier are usually mixed, the resulting slurry is thoroughly stirred, and the resulting slurry is sprayed through a nozzle and heated against heated air. Spray drying with current or co-current contact. After supporting the catalyst components in this manner, the desired catalyst can be obtained by firing at a predetermined temperature. In addition, a pentavalent vanadium compound such as ammonium metavanadate is supported on a carrier according to a conventional method, and after being calcined in air and subjected to reduction treatment in a stream of reducing gas such as hydrogen or sulfur dioxide gas, phosphorus and A catalyst supported on a desired carrier can also be obtained by impregnating it with an iron-containing solution and calcining it at a predetermined temperature.

Of course, the method of preparing these catalysts, that is, the order of addition of the vanadium compound, reducing agent, phosphorus compound, and iron compound, is not necessarily limited to the above preparation method. It does not cause any physical difference.

The catalyst of the present invention is used in a method for producing maleic anhydride by catalytically oxidizing an unsaturated hydrocarbon having 4 or more carbon atoms in a gas phase. As unsaturated hydrocarbons with carbon number of 4 or more,
For example, butenes such as butene-1 and butene-2, butadiene, benzene, pentadiene, cyclopentadiene, bempine, etc. are used.

Each of these unsaturated hydrocarbons may be a single component, or a mixture of two or more thereof may be used. Furthermore, even if a small amount of saturated hydrocarbons or unsaturated hydrocarbons having 3 or less carbon atoms such as propylene are mixed in the unsaturated hydrocarbons or mixtures thereof, this does not pose any problem. For example, it is also possible to use the C4 fraction obtained by thermal decomposition of petroleum naphtha or natural gas as it is. As an oxidizing agent for oxidizing these unsaturated hydrocarbons, molecular oxygen or molecular oxygen diluted with an inert gas such as carbon dioxide or nitrogen is used.

Air is usually used for economic reasons. The oxidation method can be carried out using either a fixed bed or a fluidized bed reaction method, but when a high concentration of hydrocarbon is used in the reaction, it is desirable to use a fluidized bed from the viewpoint of heat removal.

Furthermore, the use of a fluidized bed allows the reaction to be carried out safely even when the gas composition is within the explosive range. When carrying out the reaction in a fluidized bed, it is desirable to use a catalyst supported on a carrier. In the case of a fluidized bed, the reaction temperature is in the range of 250 to 650°C, preferably 300 to 600°C, and the space velocity (SV) is in the range of 300 to 3000 hr.
-1, preferably 500 to 2500 hr-1.

Also, is the concentration of hydrocarbons in the raw material 0.1 to 6 volumes? It's about 1 to 5 volumes? It is industrially advantageous to do so. The reaction is usually carried out under normal pressure, but if desired, it can be carried out under increased pressure (≦5 kg/(
It is also possible to carry out the reaction with 1-JMoV1G). Also,
When maleic anhydride is produced using the catalyst of the present invention, the initial activity of the catalyst can be maintained for a long period of time by carrying out the reaction while supplying a phosphorus compound to the reaction system.

The phosphorus compound supplied to the reaction zone is an organic phosphorus compound represented by the following general formula. (In the formula, R represents a phenyl group or an alkyl group having 1 to 6 carbon atoms, and X represents H or R.

) Next, the present invention will be explained in more detail with reference to manufacturing examples and usage examples, but the present invention is not limited to these embodiments unless the gist thereof is exceeded.

Reference Example 1 Vanadium pentoxide 2009 was suspended in 300 ml of water, oxalic acid 4209 was gradually added thereto, and the suspension was heated at 80° C. for 30 minutes to reduce vanadium and obtain a blue solution.

Next, this solution was cooled to room temperature, and water was added to bring the total volume to 11 (hereinafter, this solution will be referred to as vanadyl oxalate stock solution). 85 for the above vanadyl oxalate stock solution 10w11? After adding 4.579 g of a phosphoric acid solution, the mixture was heated and stirred to evaporate to dryness, and then baked at 350°C for 2 hours.
It was baked at 50°C for 2 hours. This catalyst was ground into 10 to 16 meshes (Tyra 1) to obtain a catalyst. Production Examples 1 to 4 To 10 ml of vanadyl oxalate stock solution, add 85% phosphoric acid solution and ferric chloride (FeCl3.6H20) in the amounts shown in Table 1 in this order, mix to form an aqueous solution, heat and stir. After evaporating to dryness, a catalyst was prepared in the same manner as in Reference Example 1.

Usage Example 1 A Pyrex glass reactor with an inner diameter of 1911 mm was filled with 5 ml of the catalyst prepared in the above reference examples and production examples, and air containing 4.0% of 1-butene was added to the reactor at a rate of 5 H1/Hr (NTP
maleic anhydride was produced by supplying it under normal pressure (converted).

Table 2 shows the reaction temperature giving the highest yield and the maleic anhydride yield at that time.

Claims (1)

[Claims] 1 Consists of an oxygen compound of vanadium, phosphorus, and iron, and the atomic percentage of each of these elements is 1 to 32% vanadium.
To prepare a catalyst containing 47 to 80% phosphorus and 4 to 50% iron, an aqueous solution of vanadium compound, phosphorus compound, and iron chloride is dried as it is or mixed with a carrier, and then calcined at 200 to 700°C. A method for producing a catalyst for producing maleic anhydride by gas phase oxidation of an unsaturated hydrocarbon having 4 or more carbon atoms.