JPH0140815B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively orthoalkylating phenolic compounds with alcohol. More specifically, the present invention relates to a method for carrying out the above reaction with good results and stably for a long period of time using a manganese oxide catalyst having a high porosity. Conventionally, among ortho-alkylated phenols, 2,6-xylenol in particular is a raw material for polyphenylene oxide, which has a wide range of uses as a heat-resistant resin, and much research has been conducted on its production method. As a method for ortho-alkylating phenolic compounds, there is a method that has already been industrialized, in which a phenol compound and an alcohol are reacted in the gas phase using a solid acid such as alumina as a catalyst. There is no selectivity in the position in which alkylation is performed, and alkylation occurs to a considerable extent not only at the ortho position but also at the meta and para positions, and complex separation and purification steps are required to separate the ortho-alkylated product. In addition, as another industrial method, a method using a magnesium oxide catalyst has been implemented, but this catalyst system originally has low reaction activity and the reaction temperature is low.
If the temperature is not higher than 475℃ (in practice, 500℃ or higher), not only will the reaction not proceed sufficiently, but the life of the catalyst will be short, and unless the catalyst is regenerated after every short use, it will not last for a sufficient amount of time. It has drawbacks such as being unusable. In order to solve these various problems, manganese oxide-based catalysts are used, such as catalysts based on trimanganese tetroxide (Japanese Patent Publication No. 51-11101) and catalysts in which magnesium oxide or cerium oxide is added to manganese oxide (Japanese Patent Publication No. 51-1989). -11100) and one in which silicon oxide is added (Japanese Patent Application Laid-Open No. 54-32425) have been proposed. Although manganese oxide-based catalysts have excellent orthomethylation selectivity, high reactivity, and relatively good persistence of activity, the inventors of the present invention have conducted intensive studies to further improve these properties. We discovered that a catalyst containing porous manganese oxide as a main component maintains high selectivity at the ortho position and is effective in increasing the production of ortho alkylated products per unit volume of the catalyst. The present invention has been achieved. That is, the present invention involves producing an ortho-alkylated product of a phenol compound by subjecting a phenol compound having at least one hydrogen atom at the ortho position to a gas phase catalytic reaction with an alcohol in the presence of a catalyst. This is a highly selective ortho-alkylation method for phenolic compounds, which is characterized by using a catalyst mainly composed of manganese oxide and having a high porosity of 1.5%. The phenol compound used in the present invention is a phenol compound having at least one hydrogen atom in the ortho position, and has the general formula 1 (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen, or an aliphatic hydrocarbon group such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, or tert-butyl. ). For example, phenols, ortho-meta- or para-cresols, 2,3
--・2,4-・2,5-・3,4- or 3,5
- xylenol, trimethylphenol,
Tetramethylphenols, n- or iso-propylphenols, n-/iso- or tert
- butylphenols, and phenol compounds in which two or more different alkyl groups are added to the benzene nucleus are also applicable to the present invention. The alcohol used in the present invention is a lower saturated aliphatic alcohol having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol,
These are iso-propyl alcohol, n-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, and tert-butyl alcohol. The composition of the catalyst used in the method of the present invention is one containing manganese oxide as a main component and one or more components selected from the following a, b, and c. (a) at least one selected from the group consisting of silicon oxide, germanium oxide, tin oxide, and lead oxide;
Seed component (b) At least one component selected from the group consisting of alkaline earth metal oxides and alkali metal oxides. (c) At least one component selected from the group consisting of cerium oxide and sulfate. Although it is impossible to uniformly identify the effects of the addition of substances contained in catalysts containing manganese oxide as the main component, component (a) increases the effective utilization rate of alcohol and selects ortho-alkylation. Its content is 100:0.01 to 20 in the case of silicon in atomic ratio with manganese, preferably 100:0.05.
-10, in the case of other group elements 100:0.1-50, preferably 100:0.3-30. The alkaline earth metal oxide in component (b) has the effect of increasing the stability of catalyst performance expression, moldability, and mechanical strength, and its content is preferably 100:0.01 to 30 in atomic ratio with manganese. 100: ranges from 0.05 to 20; on the other hand, alkali metal oxides reduce the rate of deposition of hydrocarbons on the catalyst surface by suppressing unnecessary decomposition of alcohol, prolonging the catalyst regeneration cycle, and increasing the catalyst's performance. It has the effect of prolonging life, and its content is 100:
The ratio is in the range of 10 ^-4 to 5, preferably 100:10 ^-3 to 1. Component (c) is particularly effective for sustaining catalyst activity, and its content is in the atomic ratio of 100:0.1 to 50 for cerium, preferably 100:0.5 to 30 for sulfur, and 100 for sulfur. :0.005~40 preferably
100: range from 0.01 to 30. A method for preparing a catalyst composition having such a composition is carried out in the same manner as previously disclosed by the present inventors, and raw materials for various metal oxides include hydroxides, halides, and carbonates of the respective metals. Salts, various mineral acid salts, oxides, organic acid salts, and in some cases sulfides and hydrides can be used. The catalyst used in the method of the present invention is obtained by calcining the catalyst composition to contain a porosity of 10 to 50%, preferably 20 to 40%, as measured by immersing the catalyst in carbon tetrachloride. Manufactured by When the porosity is 10% or less, the effect of the method of the present invention is not noticeable, and when the porosity is 50% or more, the mechanical strength of the catalyst solid is low and it is difficult to use it as an industrial catalyst. As a method for introducing high porosity, the following methods can be adopted. That is, polyvinyl alcohol, crystalline cellulose, starch, polyethylene, polypropylene, polystyrene, peat, or wood flour is added to the catalyst composition prepared by the kneading method, precipitation method, etc. disclosed by the present inventors as a pore-forming agent. etc., and kneading is carried out by dry kneading or by adding water and kneading by wet kneading for at least 30 minutes, preferably for at least 1 hour. The catalyst composition containing the pore-forming agent obtained in this way is molded using a method such as extrusion molding, compression molding, vibration molding, or rolling molding, or is crushed as it is, and then thoroughly dried at a temperature of 200°C or less. do. Firing is first carried out at a temperature range of 250 to 500℃.
After pre-calcining for 12 hours, it is fired for 3-96 hours at a temperature range of 500-1500°C and used for reaction. Further, in order to completely incinerate the pore-forming agent, it is preferable to perform the firing under air circulation or under an oxygen-rich atmosphere. Methods for changing the porosity include adjusting the amount of the pore-forming agent and changing the compression pressure during molding. As the porosity increases, the crushing strength decreases,
Although the catalyst tends to break easily, this can be improved by adding α-alumina, steatite, carborundum, etc. as a binder component to the catalyst composition. When carrying out the method of the present invention, the molar ratio of the phenol compound to alcohol is suitably from 1:1 to 1:15, preferably from 1:1 to 1:6. These raw materials can be supplied to the reaction system using an inert gas such as nitrogen or carbon dioxide as a diluent to allow the reaction to proceed smoothly. Furthermore, mixing a small amount of water into the system during the reaction not only has the effect of extending the life of the catalyst, but also has the effect of preventing the decomposition of the raw material alcohol. The reaction temperature for carrying out the method of the present invention is 300-550
C, preferably in the range of 350 to 500 C. At higher temperatures than this range, the selectivity of orthoalkylation decreases and the proportion of various high boiling point products increases. In addition, at lower temperatures than this range, the reaction rate does not increase sufficiently, and under normal reaction conditions, the reaction conversion rate is low, making it necessary to recycle a large amount of unreacted raw materials or intermediates, which is impractical. The feed rate of raw materials to the reaction system is usually preferably 0.01 to 12 hr ^-1 in terms of liquid hourly space velocity (LHSV), and generally it is appropriate that the liquid hourly space velocity is high at high temperatures and low at low temperatures. Further, although the reaction proceeds sufficiently at normal pressure, it can also be carried out under increased pressure. The reaction may be carried out in a fixed bed, fluidized bed or moving bed. The present invention will be explained below with reference to Examples. Example 1 After heating and dissolving 1000 g of manganese nitrate hexahydrate at 40°C, add 24 g of water glass No. 3 to pure water.
An aqueous solution diluted with 100 ml was added dropwise little by little. Add this silicon-containing manganese nitrate aqueous solution to pure water.
After diluting to 5000ml, add 18% ammonia water,
A precipitate of manganese hydroxide containing silicon was formed, washed with water, filtered, added with 5 g of calcium hydroxide, thoroughly kneaded, and dried at 180° C. for 8 hours. Powder obtained by pulverizing this dried precipitate
Add 50 parts by weight of crystalline cellulose powder (manufactured by Asahi Kasei Corporation, Avicel PH-101) to 100 parts by weight,
After thoroughly mixing, compression molding into cylindrical pellets with a diameter of 4.8 mm and a height of 3.0 mm was carried out at 300°C for 2 hours and at 500°C.
The Mn-
The catalyst was a Si--Ca system (Mn:Si:Ca=100:3.2:2.5 (atomic ratio)). The catalyst had shrunk to a diameter of 4.1 mm and a height of 2.6 mm, had a porosity of 35% as measured by immersion in carbon tetrachloride, and a crushing strength of 4.8 kg. Add 100ml (90g) of this to a stainless steel reactor with an inner diameter of 21mm.
filled with. A reaction raw material liquid prepared with a molar ratio of phenol and methanol of 1.5 is vaporized through a vaporizer whose temperature is adjusted to 230°C, and then introduced at a rate of 55 g/hr into a reaction tube whose internal temperature is maintained at 420°C. and started the reaction. The reaction products were quantitatively analyzed by gas chromatography. Table 1 shows the characteristics of the catalyst used and the reaction results. Note that the methanol effective utilization rate is a value calculated using the following formula. Effective utilization rate of methanol = 0 cresol produced (mo
l) + produced 26-xylenol (mol) x 2/reacted methanol (mol) x 100 Comparative Example 1 In the same manner as in Example 1, cylindrical pellets were formed without using crystalline cellulose powder as a pore-forming agent. Compression molding and the same heat treatment gave pellets with a diameter of 4.3 mm and a height of 2.7 mm. At that time, the porosity was 5% and the crushing strength was 35 kg. Using this catalyst in the same manner as in Example 1, an alkylation reaction of phenol with methanol was carried out. Table 1 shows the characteristics of the catalyst used and the reaction results. Examples 2 to 6 Catalysts with different subcomponents and porosity were prepared in the same manner as in Example 1, and reactions were carried out. Table 2 shows the characteristics of the catalyst used and the reaction results. Comparative Examples 2 to 5 In the same manner as in Examples 2 to 6, catalysts were prepared and reactions were carried out without using a pore-forming agent. Table 3 shows the characteristics of the catalyst used and the reaction results. Example 7 In the same manner as in Example 1, 50 parts by weight of crystalline cellulose powder and 2 parts by weight of α-alumina as a binder component were added to 100 parts by weight of the powder to prepare a catalyst and conduct the reaction. Ta. Table 4 shows the characteristics of the catalyst used and the reaction results.

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Claims (1)

[Claims] 1. In producing an ortho-alkylated phenol compound by subjecting a phenol compound having at least one hydrogen atom in the ortho position to an alcohol in the presence of a catalyst to produce an ortho-alkylated product of the phenol compound, 10 to 50%
A method for highly selective ortho-alkylation of phenolic compounds, which is characterized by using a catalyst mainly composed of manganese oxide, which has a high porosity.