JPH0233693B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing ortho-methylated phenol compounds by bringing phenol or/or ortho-cresol into gas phase contact with methanol in the presence of a metal oxide catalyst supported on silica using a fluidized bed reactor. It is something. Ortho-methylated phenol compounds produced by the method of the present invention, such as 2,6 xylenol, are raw materials for polyphenylene oxide, and ortho-cresol is a raw material for pharmaceutical and agricultural products, and both are important as industrial raw materials. . Methods for producing ortho-methylated phenolic compounds by contacting phenol or/and ortho-cresol with methanol in the gas phase are known, such as a method using aluminum oxide as a catalyst (British Patent No. 717588), a method using magnesium oxide as a catalyst, etc. A method using a catalyst containing iron oxide and vanadium oxide (US Patent No. 3,446,856)
37943), but all of them are implemented using a fixed bed reactor. In general, when an exothermic reaction is carried out using a fixed bed reactor, local overheating tends to occur, and it is extremely difficult to prevent local overheating, especially in an industrial scale fixed reactor, and it is difficult to obtain the desired product. This may lead to a decrease in efficiency and selectivity and shorten the life of the catalyst. Furthermore, in the orthomethylation reaction of phenols, a decomposition reaction of methanol always occurs. Since the decomposition of methanol is characterized by increasing at an accelerated rate when the reaction temperature is high, uniformity of the reaction temperature is particularly required in the orthomethylation reaction. On the other hand, when a fluidized bed reactor is used, it is easy to maintain a uniform temperature within the reactor. However, fluidized bed reactors also have problems that need to be resolved. For example, gas in a fluidized bed rises within the suspended phase of catalyst particles while mainly forming bubbles.
As they rise, they repeat coalescence and redispersion, and when these bubbles coalesce and grow, substances are exchanged between the so-called dense phase (phase with high catalyst particle density) and dilute phase (phase with low particle density). The gas mixing within each phase deteriorates, the gas-solid contact efficiency decreases, and in extreme cases gas flow-through phenomenon occurs, resulting in a significant decrease in conversion and selectivity. Furthermore, if the flow of the catalyst particles is poor, the temperature distribution will be asymmetry (localized overheating), which will impair the advantages of the fluidized bed. A problem with the conventional orthomethylation reaction of phenols is that any catalyst made of oxides such as Fe, V, Mn, Mg, Cr, In, etc. is extremely susceptible to cracking and powdering. Possible causes of this include swelling, cracking, and pulverization due to carbon deposition, strong reduction of the catalyst during the reaction, or thermal and chemical effects during catalyst regeneration due to air oxidation. For this reason, various proposals have been made to prevent catalyst pulverization in fixed bed catalysts. For example, Special Publication No. 51-42092, Special Publication No. 53-17584
Proposals have been made in JP-A-49-36705, etc. However, the strength of catalysts used in fluidized beds is not comparable to the strength required for fixed bed catalysts. This is because, unlike a fixed bed in which the catalyst is stationary, the catalyst particles collide violently with other catalyst particles or the walls of the reactor, etc., and it is essential that the catalyst has abrasion-resistant strength that can withstand this. In other words, although the fluidized bed has an extremely superior reaction formula for the orthomethylation reaction of phenols because it allows uniformity of the reaction temperature throughout the reactor,
Due to the cracking and pulverization of the catalyst peculiar to this reaction, it has not been possible to obtain a catalyst that can sufficiently withstand industrial fluidized bed reactors, and fluidized beds have been abandoned. Until now, a known example of applying a fluidized bed to the orthomethylation reaction of phenols was the use of an alumina catalyst in Japanese Patent Publication No. 52-46930, but this produced an extremely large amount of anisole and resulted in poor phenol selectivity. It has poor abrasion resistance and is a problem in industrial implementation. The present inventors overcame the problems of the fluidized bed reaction described above, developed a catalyst with good activity and selectivity, and had a long life.As a result of intensive studies, the present invention was developed in order to establish an industrially advantageous production method. reached. It is essential that the catalyst used in the present invention uses silica as a carrier. When using other carriers, such as alumina or silica/alumina, the abrasion resistance is low and the production of m-, p-cresol, which cannot be separated from 2,6-xylenol by distillation, increases dramatically. Phenol selectivity decreases significantly, such as a very large amount of anisole being produced. In addition, when diatomaceous earth, silicon carbide, or zirconia is used as a carrier, the selectivity of phenol is poor and the binding effect as a carrier is weak, so the wear resistance of the catalyst is low and the catalyst is Attrition occurs, making it unsuitable as a catalyst for fluidized beds. On the other hand, silica is selected as a carrier, and the amount of silica is 10 to 80% by weight, which is within the range of the present invention, and
If a catalyst calcined at a temperature of 500°C or more and 900°C or less is used, the strength of the catalyst will be sufficient to withstand industrial scale production. If the amount of silica is less than 10%, the strength of the catalyst is not sufficient. On the other hand, when the supported amount of silica is 80% or more, not only the activity and selectivity of the catalyst but also the strength of the catalyst are reduced, which is disadvantageous for industrial implementation. The firing temperature of the catalyst varies depending on the metal component, but is usually in the range of 500°C to 900°C. At temperatures below 500°C, sufficient activity cannot be imparted to the catalyst. The preferred firing temperature is preferably a temperature at which the silica supports the active ingredient in a substantially amorphous state. Therefore, the upper limit of the catalyst calcination temperature is selected from the range in which this amorphous state is maintained. Generally, the maximum temperature is 900℃, but the upper limit temperature is 900℃ due to the relationship with the metal components.
It may be lower than ℃. If the temperature exceeds 900°C, the crystallization of silica as a support will proceed, resulting in a decrease in catalyst strength, and the abrasion resistance will be insufficient when used as a catalyst for a fluidized bed, which is not preferable. Furthermore, in order to prevent local overheating and maintain good contact efficiency, we found that the average particle size and particle size distribution, in addition to the shape of the catalyst being close to a sphere, are extremely important. In other words, according to the experiments of the present inventors, by limiting the average particle size and particle size distribution as shown below, a good fluidity state and contact efficiency can be maintained, and good activity and selectivity can be achieved for a long period of time. Can be done. The average particle size of the catalyst is 40 to 100 μ, and the total weight of particles within each particle size range of 0.2 to 0.7 times, 1.5 to 2.0 times, and more than 2.0 times the average particle size is calculated based on the total catalyst weight. 5~50%, 5~
Good activity and selectivity can be obtained by carrying out the reaction using a catalyst having a particle size distribution of 30% or 10% or less. Methods for measuring particle size distribution include a method using a standard sieve, a method using a precipitated Tenbin, a method using an Andreasembipette, and a microscopy method. Also, the average particle size here is 50
% particle size (50% of coarse particles and fine particles in weight distribution)
For example, if the average particle size is 60μ, the total weight of particles smaller than 60μ is equal to the total weight of particles larger than 60μ. If the catalyst has a distribution narrower than the distribution specified by the present invention, or conversely if the particle size distribution is wider than the distribution specified by the present invention, the efficiency of contact between the catalyst and the gas will deteriorate, and the conversion rate of the raw material phenols will decrease. It was found that the selectivity deteriorated and the methanol selectivity decreased due to local overheating, which also had an adverse effect on the life of the catalyst. Furthermore, in order to maintain a good fluidity state, it is desirable that the gas linear velocity is in the range of 0.5 to 100 cm/sec, more preferably 2 to 80 cm/sec.
It is in the cm/second range. As the metal component of the catalyst applied to the present invention, iron, vanadium, manganese, magnesium, and chromium may be used alone or in combination (excluding cases containing both iron and vanadium). In the case of the present invention, the molar ratio of methanol to phenol or/and orthocresol in the feedstock varies depending on the catalyst species, but ranges from 1:1 to 20. Further, water vapor or an inert gas can be introduced as necessary, but in the case of water vapor, the molar ratio to phenol and/or orthocresol is preferably 1:0 to 15. The reaction temperature varies depending on the catalyst species, but is preferably in the range of 250 to 600°C. The reaction pressure may be normal pressure, but it can also be carried out under reduced pressure or increased pressure if necessary. The present invention will be explained in more detail with reference to Examples below. The phenol conversion rate, selectivity and methanol selectivity in the examples are defined by the following equations. In addition,
The same applies to orthocresol. Phenol conversion rate (%) = (1 - number of moles of unreacted phenol / number of moles of supplied phenol) × 100 Phenol selectivity (%) = (number of moles of target product produced / number of moles of supplied phenol -Number of moles of unreacted phenol) x 100 Methanol selectivity (%) = (Number of moles of orthocresol produced + Number of moles of 2,6-xylenol produced x 2/Number of moles of methanol supplied - Number of moles of unreacted Number of moles of methanol) x 100 Reference example 1 Ammonium metavanadate (NH ₄ VO ₃ ) 585
Dissolve g in 12400g of pure water heated to 90℃, and stir well to dissolve ferric nitrate (Fe(NO ₃ ) ₃・9H ₂ O).
2020gr and 2850g of silica sol (Snowtex N manufactured by Nissan Chemical) containing 30% by weight of _SiO2 are added.
A slurry of fine suspended solids uniformly dispersed in a silica colloid sol is obtained. This was dried in a co-current spray dryer. 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. The obtained dry powder was pre-calcined at 350℃ for 2 hours using a tunnel kiln, and then heated at 750℃ for 3 hours.
Time firing was performed. BET the surface area of this catalyst
The surface area was 20.5 m ² /gr when measured using a method, and it was found to have a spherical shape suitable for a fluidized bed when observed using an electron microscope. The particle size distribution was as follows. Particle size range 20~200μ Average particle size 60μ Particle size distribution 0.2~0.7 times the average particle size 35% by weight 〃 1.5~2.0 〃 16% by weight 300g of the catalyst produced by this method was placed in a fluidized bed reactor with a diameter of 1.5 inches. The reaction temperature was maintained at 320 to 330°C and the pressure was maintained at atmospheric pressure, and a raw material liquid having a ratio of phenol, methanol, and water of 1:5:3 was introduced into the reactor through the evaporator. At this time, the linear velocity of the raw material gas is
The speed was adjusted to 4.6 cm/sec. All of the gas flowing out from the reactor was passed through a condenser, and the condensed liquid was analyzed by gas chromatography. The results are shown in Table-1. A wear resistance test was also conducted on the catalyst before and after the reaction. The abrasion test is a typical test method for FCC catalysts, in which approximately 50 g of catalyst is placed in a vertical tube with an inner diameter of 1.5 inches and a perforated disc with three 1/64 inch orifices at the bottom. After being accurately weighed, it was poured into the container, and air was forced through the perforated disk at a rate of 15 cubic feet per hour to create a vigorous flow. The degree of catalyst wear was determined as the ratio of the weight of catalyst lost from the top of the vertical tube to the initial input amount, refined over a period of 5 to 20 hours. As shown in Table 1, the amount of the catalyst co-worn out before the reaction and after the reaction was around 1%, which is sufficient to withstand use as a fluidized bed catalyst. Reference Examples 2 to 6, Comparative Examples 1 to 5 Catalysts with different supported silica amounts and calcination temperatures were prepared in the same manner as in Reference Example 1, and the reaction and wear resistance of the catalysts were tested using the same equipment as in Reference Example 1. I conducted a test. The reaction lasted for 24-120 hours. Table 1 shows the reaction results and the results of the abrasion resistance test of the catalyst before and after the reaction. The particle size and particle size distribution of all the catalysts used here were within the range of the present invention. Furthermore, X-ray diffraction revealed that the silica of the catalyst calcined at 1000° C. in Comparative Example 5 was crystallized. Reference Examples 7-8 Catalysts were prepared by adding potassium and magnesium to the composition of Example 1 in the same manner as in Reference Example 1, and the reaction and abrasion resistance tests were conducted in the same manner. Display the results.
Shown in 1. The particle size and particle size distribution of all the catalysts used here were within the range of the present invention.

[Table] Examples 1 to 3, Comparative Examples 6 to 7 Catalysts with different catalyst compositions were prepared in the same manner as in Reference Example 1, and reactions and wear resistance tests of the catalysts were conducted using the same apparatus as in Reference Example 1. I did this. The reaction continued for 24 hours. Table 2 shows the reaction results and the results of the catalyst before and after the reaction. The particle size and particle size distribution of all the catalysts used here were within the range of the present invention.

[Table] Comparative Example 8 Manganese nitrate was dissolved in commercially available alumina sol (10 wt% as Al ₂ O ₃ ), spray-dried in the same manner as in Example 1, and calcined at 700°C for 3 hours. A wear resistance test was conducted on this catalyst. The results are shown in Table 3. Comparative Example 9 100 to 200 meshes of commercially available diatomaceous earth were impregnated with manganese nitrate and fired at 700°C for 3 hours.
A wear resistance test was conducted on this catalyst. The results are shown in Table 3.

[Table] Reference Example 9 Using the catalyst used in Reference Example 1, ortho-cresol and methanol were reacted in the same reaction apparatus as in the example. At this time, the reaction temperature was 320℃,
The molar ratio of orthocresol, methanol, and water was 1:3:3, and the gas linear velocity was maintained at 4.6 cm/sec. After continuing the reaction for 24 hours, the conversion rate of orthocresol was 99.5% 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 supported on silica, with iron as the metal component,
The reaction is carried out in a fluidized bed using a metal oxide catalyst consisting of vanadium, manganese, magnesium, and chromium alone or in combination (excluding cases containing both iron and vanadium) and calcined at 500 to 900°C. 1. A method for orthomethylating phenol or/and orthocresol. 2. The catalyst has an average particle size of 40 to 100μ, and the total weight of particles in each particle size range of 0.2 to 0.7 times, 1.5 to 2.0 times, and over 2.0 times the average particle size is relative to the total catalyst weight, 5-50%, 5-30% and 10 respectively
The method for orthomethylating phenol and/or orthocresol according to claim 1, characterized in that the particle size distribution is less than or equal to %. 3 The linear velocity when the reaction gas of phenol or/and orthocresol and methanol contacts is
The method for orthomethylating phenol and/or orthocresol according to claim 1, characterized in that the rate is 0.5 to 100 cm/sec.