JPH0133090B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing alkylphenols by catalytically reacting phenols and alcohols. In particular, the present invention relates to a method for producing alkylphenols having at least one alkyl group by alkylating hydrogen atoms of phenols using a metal oxide-containing catalyst pretreated with phenols. It is known that alkylphenols, especially the orthoalkylated product 2,6-dimethylphenol, are important as raw materials for the production of polyphenylene ether (PPE), a useful plastic. In addition, alkylphenols include resins, plasticizers,
It is also known that numerous studies have been conducted on it for its use as a raw material for antioxidants, fungicides, and agricultural chemicals. In the alkylation method of phenols, aluminum oxide, magnesium oxide, manganese oxide, iron oxide, chromium oxide, zeolite, etc. and their additions with various components have already been used as catalysts to bring phenols and alcohols into contact. Although methods for reacting are known, when considering the overall performance of the catalyst, all of these methods are insufficient in terms of activity, selectivity, induction period, lifespan, etc., and cannot be said to be a satisfactory catalyst. From this perspective, the present inventors continued intensive research in order to solve these problems, and found that by pre-treating the metal oxide-containing catalyst with phenols prior to providing it to the alkylation reaction. We found that these problems can be easily improved and arrived at the method of the present invention. That is, the present invention provides a method for producing alkylphenols by catalytically reacting phenols having at least one hydrogen atom on an aromatic ring with alcohols, in which a metal oxide-containing catalyst is pretreated with a phenol. This is a method for producing alkylphenols, which is characterized in that the method is used for the production of alkylphenols. The phenols used in the method of the present invention are phenol compounds having one or more hydrogen atoms on the aromatic ring, and have the general formula (In the formula, R ₁ to _{R 5} are hydrogen, a hydrocarbon group, a hydroxyl group, or an aromatic hydrocarbon group such as unsubstituted or substituted phenyl or naphthyl, and at least one of them is a hydrogen atom. ). Examples of such compounds include phenols, cresols, xylenols, trimethylphenols, various ethylphenols, n
-, iso-, tert- butylphenols, phenylphenols, naphthylphenols, and the like. Similarly, phenol compounds in which one or more different functional groups are substituted on the aromatic ring can also be used. The alcohols used in the method of the present invention are:
It is a lower alcohol having 1 to 4 carbon atoms, such as methanol, ethanol, n-propanol, iso
-propanol, n-butanol, iso-butanol, tert-butanol, etc. Examples of the catalyst used in the method of the present invention include aluminum oxide-containing catalysts, magnesium oxide-containing catalysts, manganese oxide-containing catalysts, iron oxide-containing catalysts, and zeolite-containing catalysts. That is, aluminum oxide-containing catalysts include aluminum oxide alone and aluminum oxide as the main component, and silicon oxide, for example, and magnesium oxide-containing catalysts include magnesium oxide alone and aluminum oxide as the main component, and manganese oxide, for example. , copper oxide, boron oxide, silicon oxide, iron oxide, and the like. In addition, the manganese oxide-containing catalyst may include manganese oxide alone or manganese oxide as a main component, and one or more selected from magnesium oxide, silicon oxide, iron oxide, alkali metals, alkaline earth metals, sulfuric acid radicals, etc. Catalysts containing two or more types, iron oxide-containing catalysts include iron oxide alone or iron oxide as a main component, and a catalyst selected from silicon oxide, chromium oxide, zinc oxide, manganese oxide, alkali metals or alkaline earth metals, etc. It contains one or more types. Furthermore, as a zeolite-containing catalyst, the central anion of various zeolites such as X-type and Y-type can be combined with one or more of proton, lanthanum, nickel, copper, manganese, chromium, cobalt, boron, zinc, cadmium, alkali metals, and alkaline earth metals. These include those containing cation-exchanged zeolite. As raw materials for various oxides used in these catalysts, common compounds such as respective metal oxides, hydroxides, halides, nitrates, sulfates, carbonates, and organic acid salts are used. The catalyst can be prepared by mixing various raw materials, adding a small amount of water, and kneading with a kneader, mixer, etc., or by adding a basic component to an aqueous solution of various raw materials and co-precipitating it as an insoluble precipitate. If necessary, ordinary preparation methods such as filtering, washing, drying, baking, and molding can be used as is. Further, in the case of a zeolite-containing catalyst, a normal ion exchange method can be applied. The metal oxide-containing catalyst used in the method of the present invention may be treated with phenols by the following method, but any method may be used. (A) A method in which the catalyst is pretreated by bringing it into contact with a gas or liquid containing phenols before charging the catalyst into a reactor. (B) A method in which the catalyst is pretreated by filling the catalyst into a reactor and then bringing it into contact with a gas or liquid containing phenols in the reactor. The phenols used for pretreatment of the catalyst are generally basically the same as the compounds shown in parentheses, but at least one of R ₁ to _{R 5} does not need to be a hydrogen atom. Furthermore, when treating with these phenols, the phenols may be a single type or a mixture of two or more types. Further, a suitable gas (inert rare gas, water vapor, nitrogen gas, reducing gas, etc.) may be included. The treatment with the above phenols is carried out at a temperature ranging from room temperature to 800°C for 20 minutes to 48 hours. The catalyst whose activity has decreased after being used in the reaction is activated by a gas containing oxygen and water vapor, and then pretreated with the phenols described above again. Although the theoretical interpretation of the effect of the pretreatment with phenols in the method of the present invention is not necessarily clear, the treatment with phenols causes the phenols to be adsorbed onto the catalyst surface, and during the reaction, the phenols are absorbed into the alkylating agent and the alkylated target. It is believed that when approached by the agent, it provides a favorable field for activity and selectivity. Furthermore, the shortening of the induction period is thought to be due to the fact that active sites are sufficiently generated at the start of the reaction. Furthermore, the effect on the lifespan is thought to be that the alkylating agent decomposes and the active sites that would be carbonized are inactivated by the adsorption of phenols, thereby preventing carbonization. When carrying out the method of the present invention, the molar ratio of phenols and alcohols to be supplied is suitably 4:1 to 1:10, more preferably 3:1 to 1:8. Conducting the reaction by mixing water into the reaction raw materials has the effect of further extending the life of the catalyst and suppressing unnecessary decomposition of alcohols. In the method of the present invention, the reaction temperature is 300-570
℃, preferably in the range of 310 to 530℃. If the reaction temperature is lower than this range, the conversion rate will be insufficient in the usual reaction format and it is not practical, and if the reaction temperature is set higher than this range, the selectivity of the reaction tends to decrease. The reaction can be carried out in liquid phase, gas phase, pressurized, normal pressure, or reduced pressure, and the reaction format can be fixed bed, moving bed, or fluidized bed, but fixed bed is generally used. . EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the contents of these Examples. The catalyst performance in Examples 1 to 4 was determined by the conversion rate,
2,6-xylenol selectivity, each defined by the following formula. Conversion rate (mol%) = Conversion rate of phenol (mol%) = (1
- Amount of unreacted phenol (mol) / Amount of phenol supplied (mol)) x 100 2,6-xylenol selectivity (based on phenol) = Amount of 2,6-xylenol produced (mol) /
Amount of phenol supplied (mol) - Amount of unreacted phenol (mol) x 100 2,6-xylenol selectivity (methanol standard) = 2 x Amount of 2,6-xylenol produced (mol) / Amount of methanol supplied (mol) - Unreacted Methanol amount (
mol) x 100 The catalyst performance in Example 5 is shown by the conversion rate of the raw material meta-cresol and the selectivity of the target product, each of which is defined corresponding to the above formula. Example 1 The reactor used for the alkylation consisted of phenol and methanol feed pumps, a raw liquid vaporizer, a quartz glass reactor, and a product vapor condensation section. The center of a quartz glass reactor was filled with 20 ml of catalyst containing 10 to 20 meshes and placed in an electric furnace. The catalyst was commercially available magnesium oxide, and after installing it in the above-mentioned apparatus, the temperature of the catalyst layer was set to 500°C.
The treatment was carried out by supplying only phenol at a rate of 10 ml/hr for 3 hours. Next, phenol, methanol and water (supplied molar ratio 1:5:1.7) were supplied at a liquid hourly space velocity of 1.65 hr ^-1 to carry out a reaction for the purpose of producing 2,6-xylenol. The results are shown in Table 1.

[Table] As Comparative Example 1, the results are shown when the reaction was carried out in exactly the same manner as in Example 1, except that the catalyst was not pretreated with phenol. Example 2 The catalyst used was manganese dioxide, the reaction temperature and catalyst treatment temperature were 430°C, and the liquid hourly space velocity was
The reaction was carried out in the same manner as in Example 1 except that the reaction time was 1.13 hr ^-1 . The results were as shown in Table 2. Comparative Example 2 shows the results obtained when the reaction was carried out in exactly the same manner except that the catalyst was not pretreated with phenol.

[Table] Example 3 Example except that magnesium oxide was used as the catalyst, and the catalyst was immersed in ortho-cresol maintained at 120°C for 2 hours, then placed in the reaction apparatus, and placed in a nitrogen stream at the reaction temperature. The reaction was carried out in the same manner as in 1. The results were as shown in Table 3. As Comparative Example 3, the results are shown in which the catalyst was not pretreated with orthocresol.

[Table] Example 4 The catalyst used was ferric oxide, the reaction temperature and catalyst treatment temperature were 370°C, and phenol alone was
ml/hr for 3 hours, and the same method as Example 1 except that phenol, methanol and water (supplied molar ratio, 1:3:1.1) were supplied at a liquid hourly space velocity of 1.14 hr ^-1 . The reaction was carried out for the purpose of producing 2,6-xylenol, and the results are shown in Table 4. As Comparative Example 4, the results are shown in which the reaction was carried out in exactly the same manner as in Example 4, except that the catalyst was not pretreated with phenol.

[Table] Example 5 The reactor used for the alkylation consisted of metacresol and methanol feed pumps, feed liquid vaporizer, reactor, product vapor condensation and receiver. Prior to the methylation reaction, only metacresol was added.
After pretreating the catalyst by supplying it to the magnesium oxide catalyst bed at 420°C for 3.5 hours, the reaction temperature was then increased.
Table 5 shows the results of the reaction carried out at 450°C, molar ratio of metacresol and methanol of 1:7, and liquid hourly space velocity of 0.74 hr ^-1 . Comparative Example 5 shows a case in which the reaction was carried out in exactly the same manner as in Example 5, except that the catalyst was not pretreated with metacresol.

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Claims (1)

[Claims] 1. In a method for producing alkylphenols by catalytically reacting phenols having at least one hydrogen atom on an aromatic ring with alcohols, at least one selected from the group consisting of magnesium oxide, manganese oxide and iron oxide is used. 1. A method for producing alkylphenols, characterized in that a catalyst consisting of one type of catalyst is pretreated with a phenol.