JPS632540B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an ortho-methylated phenol compound by contacting phenol or/or toltocresol with methanol in the gas phase in the presence of a catalyst containing vanadium oxide and iron oxide supported on silica. . Each of the ortho-methylated phenol compounds produced by the method of the present invention is important as an industrial raw material. For example, 2,6-xylenol is a raw material for polyphenylene oxide, and ortho-cresol is a raw material for agricultural medicines. . A method for producing an ortho-methylated phenol compound by contacting phenol or/and ortho-cresol with methanol in a gas phase is known.
Method using aluminum oxide as catalyst (British patent no.
717588) and a method using magnesium oxide as a catalyst (US Pat. No. 3,446,856). However, when the former catalyst is used, the activity and ortho-position selectivity are low, and methylated phenols at the meta- and para-positions are produced as by-products. Separating 2,6-xylenol from these mixtures requires complicated separation and purification steps, and is not an advantageous method for industrial implementation. Moreover, in the case of the latter catalyst, since the catalytic activity is low, it is necessary to maintain the reaction temperature at an extremely high temperature of 475 to 600° C., and in addition, it has the disadvantage that the activity decreases quickly. On the other hand, in order to solve these drawbacks, a catalyst containing vanadium oxide and iron oxide has been proposed (Japanese Patent Publication No. 47-37943). This catalyst has high activity and 300
It is possible to react at a relatively low temperature of ~400℃, and also has high ortho-position selectivity.
Since the strength of the catalyst is not sufficient, the catalyst cracks and becomes powder during the reaction, resulting in a large pressure loss in the catalyst layer, which has the disadvantage that continuous operation is impossible. The reason for this is presumed to be that carbon is deposited on the catalyst during the reaction, which causes swelling, cracking, and powdering. For this reason, a method has been proposed to suppress cracking and powdering of the catalyst by adding steam to the reaction system (Japanese Patent Publication No. 10226/1973), but although it is effective to some extent, it does not last long. When the reaction is carried out, cracking and powdering of the catalyst occur, which is a serious drawback in industrial implementation, and no fundamental solution has been reached. The present inventors have developed an industrial catalyst for producing ortho-methylated phenolic compounds by bringing phenol or/and ortho-cresol into gas phase contact with methanol, that is, having high activity and high selectivity, and under a reaction atmosphere. However, as a result of intensive research to develop a vanadium-iron composition catalyst that has sufficient strength and a long life, and is suitable for both fluidized bed and fixed bed reactors, we have developed a catalyst that can be fired at a temperature of 550℃ or higher. It has been found that the above-mentioned problem can be solved by using a catalyst supported on silica containing vanadium oxide and iron oxide in an amount of 10 to 80% by weight, leading to the completion of the present invention. That is, the present invention includes vanadium oxide and iron oxide calcined at a temperature of 550°C or higher in producing an ortho-methylated phenol compound by contacting phenol or/and ortho-cresol with methanol in a gas phase. A method for producing an ortho-methylated phenol compound, characterized in that ~80% by weight of a catalyst supported on silica is used. In the catalyst used in the present invention, it is essential to use silica as a carrier. Special Public Service 1977-
The specification of No. 37943 states that ``the catalyst can also be used with a suitable support such as alumina, silica, silica-alumina, diatomaceous earth, etc.'', but it describes an example in which 10% by weight of alumina was supported. It's just that it's being done. According to the experiments conducted by the present inventors, in this reaction, the type of support has an extremely large effect on the activity, selectivity, and strength that should be imparted to the catalyst, so it should not be selected arbitrarily, but must be strictly selected. It is something that should be done. For example, when alumina or silica-alumina is selected as a carrier, the ortho position selectivity is markedly increased, such as the production of m- and p-cresol, which cannot be separated from 2,6-xylenol using normal methods. descend. In addition, when diatomaceous earth, silicon carbide, or zirconia is used as a carrier, the ortho position selectivity is low and the binder effect is low.
Since the strength of the catalyst is low and peeling, powdering, etc. occur in a short period of time, this method has serious drawbacks in industrial implementation. On the other hand, silica is selected as a carrier, and the supported amount of silica is within the range of the present invention.
When the content is 80% by weight, the activity, ortho-position selectivity, and strength of the catalyst are sufficiently satisfied industrially, and the reaction can withstand a long period of time. If the supported amount of silica is less than 10%, which is outside the scope of the present invention, the strength of the catalyst will not be sufficient. In particular, when carrying out a reaction using a fluidized bed reactor, the abrasion resistance of the catalyst is required to be significantly higher than that in a fixed bed, but the amount of silica supported within the scope of the present invention is 10% or more, preferably 20%. If it is above, it can sufficiently withstand a fluidized bed. On the other hand, the amount of silica supported
When it exceeds 80%, not only the activity and selectivity of the catalyst decrease, but also the strength of the catalyst decreases, which is disadvantageous for industrial implementation. The silica-supported catalyst used in the present invention is normally heated at a temperature of 550 to 1000°C, in some cases over 1000°C, preferably 650 to 900°C, in order to impart catalytic activity, selectivity and strength. It is necessary to fire at a high temperature exceeding . When the calcination temperature is lower than the range of the present invention, the activity of the catalyst,
The selectivity and intensity are insufficient, and a decrease in activity over time is observed. On the other hand, the firing temperature is 1000
If the temperature is higher than 0.degree. C., the catalyst activity tends to decrease slightly, but it can still be used industrially. However, this method is not advantageous due to problems with firing equipment and energy saving. The atomic ratio of vanadium to iron in the catalyst is preferably 1:9 to 9:1, preferably 1:2 to 2:1. The method for producing orthomethylated phenol compounds of the present invention can be carried out in either a fluidized bed reactor or a fixed bed reactor. Generally, when a fluidized bed reactor is used, heat can be easily removed and a uniform reaction temperature can be obtained, making it suitable for large-scale production. When carrying out the reaction in a fluidized bed, in order to provide good fluidity, the catalyst must have a spherical shape with a diameter of several tens to hundreds of microns, and be worn out by collisions between catalyst particles or between particles and the vessel wall. Therefore, it is necessary to have abrasion resistance strength that can withstand this. On the other hand, when used in a fixed bed reactor, in order to reduce pressure loss in the catalyst layer,
Generally, catalysts shaped into columns, spheres, or pellets are used, but if the catalyst is crushed or powdered during the reaction, pressure loss will occur in the catalyst layer, making it difficult to continue operation. It is essential that the catalyst has sufficient strength when exposed to the reaction atmosphere for long periods of time. As a raw material for the catalyst in the present invention, ammonium salts, chlorides, and oxychlorides are used as vanadium sources, and it is preferable to use them in the form of ammonium salts. As the iron source, nitrates, chlorides, sulfates, or organic acid salts can be used, and it is preferable to use them in the form of nitrates. Further, as the silica source, it is preferable to use silica sol. Catalyst Preparation Method (A) Example of Preparation Method for Fluidized Bed Catalyst First, a raw material slurry is prepared by adding ferric nitrate and silica sol to a solution of ammonium metavanadate in hot water while stirring. This can be carried out suitably. Here, a slurry of fine suspended solids uniformly dispersed in a silica colloid sol is obtained. The slurry is then dried using a known spray drying device,
Obtained as spherical dry particles. Atomization of the raw material slurry can be carried out by any of the centrifugal, two-fluid nozzle, or high-pressure nozzle methods commonly used in industrial practice, but the centrifugal method is particularly preferred. In the centrifugal system, the particle size can be distributed between 10 and 150 microns, which is suitable for use in a fluidized bed reactor, by adjusting the rotation speed of the disk and the feed rate of the slurry. Finally, the dried product is heat treated and fired using a conventional tunnel or rotary kiln. (B) Example of preparation method for fixed bed catalyst Ammonium metavanadate is dissolved in hot water, ferric nitrate is added, and then neutralized with ammonia.
The formed precipitate is washed with water, dried and pulverized, then silica sol is added, thoroughly kneaded and molded into a suitable shape. Alternatively, silica sol can be added to particles obtained by denitrating the spray-dried particles at a low temperature as described in the method for preparing a fluidized bed catalyst (A), and the particles can be thoroughly kneaded and molded into a suitable shape. This molded product is heat-treated and fired using a conventional tunnel kiln. As is clear from the above, the catalyst of the present invention preferably contains 10 to 80% by weight of vanadium oxide and iron oxide calcined at a temperature of 550°C or higher.
The 20-80% by weight silica-supported catalyst has excellent activity, selectivity and catalytic strength for long-term reactions, and surprisingly, even in the absence of water in the reaction system. , has sufficient catalytic strength to withstand long-term reactions, and allows industrially advantageous production of orthomethylphenol compounds. In the case of the present invention, the ratio of methanol to phenol or/and orthocresol in the feed is from 1:1 to 20, preferably from 1:2 to 8. Moreover, water vapor or inert gas can also be introduced as necessary. Reaction temperature is 280~500℃,
Preferably, a temperature range of 300 to 400°C is suitable. The reaction pressure may be normal pressure, but it can also be carried out under reduced pressure or increased pressure, if necessary. The contact time between the gas and the catalyst is suitably 0.5 to 50 seconds, preferably 1 to 20 seconds. Hereinafter, the present invention will be explained in more detail with reference to Examples. The phenol conversion rate and selectivity in the examples are defined by the following formula. The same applies to ortho-cresol. Phenol conversion rate (%) = (1 - number of moles of unreacted phenol/number of moles of supplied phenol) x 10
0 Selectivity (%) = (Number of moles of target product produced/Number of moles of supplied phenol - Number of moles of unreacted phenol) x 100 Example 1 Ammonium metavanadate (NH ₄ VO ₃ ) 23.4
Dissolve g in 496 g of pure water heated to 90°C, add ferric nitrate [Fe
A raw material slurry obtained by adding 80.8 g of (NO ₃ ) ₃ ·9H ₂ O] was evaporated to dryness on a hot water bath, and then preliminarily calcined at 350° C. for 2 hours. After taking 20g of this and pulverizing it, 28.6g of silica sol (Snowtex N manufactured by Nissan Chemical) containing 30% by weight of SiO ₂ was added, and the mixture was thoroughly kneaded while heating on a hot water bath to reach an appropriate moisture concentration that can be molded. After adjusting, the diameter is 5mm,
It was molded into a cylindrical shape with a length of 5 mm. This at 100℃ for 12
After drying for an hour, it was fired at 700°C for 3 hours. A glass reaction tube with an inner diameter of 2 cm was filled with 6 c.c. of this catalyst, and the reaction temperature was maintained at 320°C and the pressure at atmospheric pressure.
In this, the molar ratio of phenol and methanol is 1:
The raw material solution No. 5 was introduced through the evaporator. At this time, the flow rate was adjusted so that the contact time between the raw material gas and the catalyst was 3.5 seconds, and the reaction was continued for 48 hours. At 48 hours, all the gas flowing out from the reactor is condensed,
The condensate was analyzed by gas chromatography. The results are shown in Table 1. Further, after the reaction, the catalyst was taken out and sieved through a 16-mesh sieve, and the powdering rate was defined as the ratio of the material that passed through the mesh to the total weight, and the powdering rate of this catalyst was 0.1% or less. Comparative Examples 1 to 3 A supported alumina catalyst and a supported bentonite catalyst were prepared in substantially the same manner as in Example 1, and a reaction test was conducted using the same apparatus as in Example 1 under the same conditions. Therefore, 20% by weight alumina sol (manufactured by Nissan Chemical) was used as the alumina, and chemical grade bentonite manufactured by Kukita Pharmaceutical was used. The test results are shown in Table 1.

[Table] Comparative Example 4 In substantially the same manner as in Example 1, shaped catalysts supported on diatomaceous earth and silicon carbide were prepared. A reaction was carried out using this catalyst using the same apparatus as in Example 1 and under the same conditions. The powdering rate of the catalyst after the reaction was 8% for the diatomaceous earth supported catalyst and 12% for the silicon carbide catalyst, and it was determined that the catalyst was powdered during the reaction and would be difficult to use industrially. . Comparative Example 5 100g of ferric nitrate [Fe(NO ₃ ) ₃・9H ₂ O] in pure water
Dissolve in 200c.c. 14% ammonia water with stirring
94c.c. was added dropwise to adjust the pH to 6.8. After washing the generated precipitate with water, 25 g of it was added to 50 c.c. of an aqueous solution of 7.2 g of ammonium metavanadate (NH ₄ VO ₃ ) and 1 g of oxalic acid, concentrated to dryness on a hot water bath, and then heated in air at 450°C.
The catalyst was fired for 3 hours to prepare an unsupported vanadium oxide-iron oxide catalyst (V/Fe=1). After pulverizing this catalyst, a small amount of water and 1% carbon black were added to the catalyst, and the mixture was formed into a cylinder with a diameter of 5 mm and a length of 5 mm using a hydraulic press, and dried at 100° C. for 12 hours. A reaction was carried out using this catalyst using the same apparatus as in Example 1 and under the same conditions. The powdering rate of the catalyst after the reaction was 25%. Example 2 Ammonium metavanadate (NH ₄ VO ₃ ) 585
Dissolve g in 12,400 g of pure water heated to 90°C, add ferric nitrate [Fe
(NO ₃ ) ₃・9H ₂ O] Silica sol containing 2020g and 30% by weight of SiO ₂ (Snowtex N manufactured by Nissan Chemical)
The raw material slurry obtained by adding 2850 g was sent to a co-current spray dryer and dried. The obtained dry powder was heated at 350℃ using a tunnel kiln.
After preliminarily firing for 2 hours at 750°C, firing was performed for 3 hours. The surface area of this catalyst was measured by the BET method and was 20.5 m ² /g, and observation with an electron microscope showed that it had a spherical shape suitable for the fluidized bed method. 300 g of this catalyst was put into a fluidized bed reactor with a diameter of 1.5 inches, the reaction temperature was kept at 320-330°C, the pressure was kept at atmospheric pressure, and the ratio of phenol, methanol, and water was 1:
A 5:3 raw material solution was introduced into the reactor through the evaporator. At this time, the contact time between the raw material gas and the catalyst is 6.0
The flow rate was adjusted so that the flow rate was within seconds. All of the gas flowing out from the reactor was passed through a condenser, and the condensed liquid was analyzed by gas chromatography. This reaction was carried out continuously for 240 hours. The reaction results are shown in Table 2. In addition, abrasion resistance tests were conducted on the catalysts before and after the reaction. The abrasion resistance test is carried out as a normal test method for FCC catalysts.
The catalyst was placed in a 1.5 inch inner diameter vertical tube with a perforated disc with three 64 inch orifices.
50 g was accurately weighed and air was forced through the perforated disk at a rate of 15 cubic feet per hour to create a vigorous flow. Catalyst wear was refined over a period of 5 to 20 hours and determined as the ratio of the weight of catalyst lost from the top of the vertical tube to the initial charge. The results are shown in Table 2. Examples 3 to 8, Comparative Examples 6 to 9 Catalysts with different supported silica amounts and calcination temperatures were prepared in the same manner as in Example 2.
The reaction was carried out using the same experimental equipment. The reaction is
It continued for 24 to 120 hours. Table 2 shows the reaction results and the abrasion resistance test results of the catalyst before and after the reaction. Note that nitrate was used as the Mg source in the examples.

[Table] Examples 10 to 16 Catalysts with various compositions, silica supported amounts, and calcination temperatures were prepared by the same method as in Example 2,
The reaction was carried out using the same experimental apparatus as in Example 1. The reaction continued for 24-120 hours. The reaction results are shown in Table 3. Note that nitrate was used as the Mn source in the examples.
Furthermore, titanium tetrachloride was used as a Ti source.

[Table] Example 17 Using the catalyst used in Example 2 and using the same reactor as in Example 1, ortho-cresol and methanol were reacted. At this time, the reaction temperature is
The temperature was 320°C, the pressure was atmospheric pressure, the molar ratio of orthocresol, methanol and water was 1:3:3, and the contact time was maintained at 5 seconds. After continuing the reaction for 24 hours, the reaction results showed that the conversion rate of orthocresol was 99.6% and the selectivity of 2,6-xylenol was 98.5%.

Claims (1)

[Claims] 1 In producing an ortho-methylated phenol compound by contacting phenol or/and ortho-cresol with methanol in the gas phase, 10 to 80% by weight of vanadium oxide and iron oxide calcined at a temperature of 550°C or higher is used. A method for producing an ortho-methylated phenol compound, the method comprising using a catalyst supported on silica.