JPH0141612B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively orthoalkylating phenolic compounds with alcohols. More specifically, the present invention relates to a method of carrying out the reaction with good results and stably for a long period of time by using a catalyst containing manganese oxide as a main component after being sintered by high-temperature heat treatment. Conventionally, among ortho-alkylated phenols, 2,6-xylenol in particular serves as a raw material for polyphenylene oxide, which has a wide range of uses as a heat-resistant resin, and therefore, much research has been conducted on its production method. As a method for ortho-alkylating phenolic compounds, one that has already been industrialized is a method in which a phenolic compound and alcohol are reacted in the gas phase using a solid acid such as alumina as a catalyst.
This method has no selectivity for the alkylated position of the phenolic compound, and alkylation occurs to a considerable extent not only at the ortho position but also at the meta and para positions.
Complex separation to separate ortho-alkylated products;
Requires purification process. 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. Several manganese oxide catalysts have been proposed to solve these various problems. Regarding manganese oxide-based catalysts, differences in catalytic performance are recognized depending on the firing conditions, and according to Japanese Patent Publication No. 11101/1983, it is preferable to fire manganese oxides at temperatures of 400 to 1500°C, especially at temperatures above 950°C. It is known that the calcined product is highly active and takes the form of trimanganese tetroxide. Furthermore, Japanese Patent Publication No. 55-30493 describes that a catalyst composed of cerium oxide and manganese oxide calcined at a temperature of 600°C or higher and 1000°C or lower is even more excellent. One of the applicants of this application has already applied for a patent on December 13, 1972 for "Selective ortho-alkylation method of phenol compounds" (Japanese Patent Application Laid-open No. 81231-1973).
A catalyst is disclosed in which one or more selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide is added to manganese oxide and silicon oxide, and the firing temperature is 300 to 900°C. Furthermore, in ``Method for producing ortho-alkylated phenols'' (Japanese Unexamined Patent Publication No. 76830/1983), for which a patent application was filed on December 1, 1971, a catalyst composition consisting of manganese oxide and silicon oxide, or an alkaline earth A manganese oxide-containing catalyst obtained by modifying a catalyst composition containing one or more selected from metal oxides with one or more compounds of alkali metals. Disclosed. Although these manganese oxide catalysts have excellent orthomethylation selectivity, high reactivity, and relatively good persistence of activity, they have a problem that the effective utilization rate of methanol is rather low. The present inventors conducted research into a catalyst that would reduce the unnecessary decomposition of alcohols while maintaining the excellent properties of the manganese oxide catalyst, and as a result, they applied high-temperature heat treatment to the manganese oxide catalyst to essentially sinter it. It was discovered that the catalyst exhibits extremely good properties, and the present invention was further completed. That is, the present invention provides at least one ortho position.
In producing an orthoalkylated product of the phenolic compound by subjecting a phenolic compound having 1 or more hydrogen atoms and an alcohol to a gas phase catalytic reaction in the presence of a catalyst, manganese oxide, a silicon oxide and A catalyst containing at least one component selected from the group consisting of tin oxide and/or b) at least one component selected from the group consisting of calcium oxide and potassium oxide is subjected to heat treatment in the range of 1000° to 1500°C. This is a method for highly selective orthoalkylation of phenolic compounds, which is characterized in that the phenolic compounds are added and sintered, and then used in the reaction. The phenolic compound used in the present invention is a phenolic compound having at least one hydrogen atom in the ortho position, and is represented by the general formula (1). (In the formula, R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen or aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, and tert-butyl. ). For example, phenolic, ortho-metal or para-cresols, 2,3
--・2,4-・2,5-・3,4- or 3,5
-xylenol, trimethylphenol, tetramethylphenol, n- or iso-propylphenol, n-/iso- or tert-
Examples include butylphenols, and phenol compounds in which two or more different alkyl groups are added to a benzene nucleus can also be applied to the present invention. The alcohols used in the present invention are lower saturated aliphatic alcohols having 1 to 4 carbon atoms,
For example, methyl alcohol, ethyl alcohol, iso-propyl alcohol, n-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, tert-butyl alcohol. The catalyst used in the method of the present invention is mainly composed of manganese oxide, and further includes the following a) and/or
or b). a At least one component selected from the group consisting of silicon oxide and tin oxide, b At least one component selected from the group consisting of calcium oxide and potassium oxide, and the effect of adding these components contained in manganese oxide. Although there are some points that are impossible to uniformly identify,
a) Ingredients increase the effective utilization rate of alcohol,
It has the effect of increasing the ortho-alkylation selectivity, and its content is higher than that of silicon in terms of atomic ratio with manganese.
100:0.01~20 preferably 100:0.05~10 range,
For other group elements 100: 0.1-50 preferably
100: range from 0.3 to 30. Calcium oxide in component b) has the effect of increasing the stability of catalyst performance, moldability, and mechanical strength. Its content is expressed in atomic ratio with manganese.
100:0.01-30 preferably in the range of 100:0.05-20, while potassium oxide reduces the deposition rate of hydrocarbons on the catalyst surface by suppressing unnecessary decomposition of alcohols, and improves the catalyst regeneration cycle. Its content is 100:10 ^-4 to 5 in atomic ratio with manganese.
Preferably it is in the range of 100:10 ^-3 to 1. Raw materials for various metal oxides used in the method of the present invention include hydroxides, halides, carbonates, various mineral acid salts, organic acid salts, and in some cases sulfides and hydrides of the respective metals. can be used. The method for producing the catalyst is to mix the various raw materials listed above,
A method of adding a small amount of water, thoroughly kneading it with a kneader, mixer, etc., and drying it; a method of making various raw materials into an aqueous solution and adding a basic component to this to co-precipitate as an insoluble precipitate; or a method of co-precipitating some of the components. Various methods are possible for mixing, such as separate methods such as immersion and kneading. The obtained catalyst composition is usually dried at a temperature of 200°C or less, and if necessary,
Appropriate additives and molding aids such as PVA and crystalline cellulose are added, and the material is molded by methods such as extrusion molding, compression molding, vibration molding, and rolling molding, and is pre-baked if necessary. The catalyst composition thus formed is subjected to high temperature heat treatment, that is, in a temperature range of 1000 to 1500°C. At temperatures below 1000°C, sintering does not proceed, so the improvement effect of the present invention is not observed even when subjected to reaction, and at temperatures above 1500°C, sintering progresses to an extreme level, resulting in a decrease in activity, which is preferable. do not have. The time for the high-temperature heat treatment needs to be in the range of 3 to 96 hours, and more preferably in the range of 5 to 72 hours. The surface area of the catalyst substantially sintered by high temperature heat treatment is preferably in the range of 0.005 to 5 m ² /g, more preferably 0.01 to 2 m ² /g. Also,
As a binder component, it is also possible to use a mixture of so-called sintered bodies such as α-alumina, steatite, and carborundum. When the constituent particles of the catalyst, which is mainly composed of manganese oxide and subjected to the high-temperature heat treatment described above, are observed using an electron microscope, spherical-like particles with a diameter of several μm and cubic-like particles of the same size are observed, and there are gaps between the particles. It can be seen that sintering is progressing. A notable effect of sintering the catalyst by applying such high-temperature heat treatment is that it reduces unnecessary decomposition of alcohols, but this is because high-temperature sintering reduces undesirable active sites on the catalyst ( This is thought to be because the ratio of active sites that are not effective for alkylation reactions and only decompose alcohols is decreased, and the ratio of active sites that are effective for alkylation reactions is relatively increased. Catalytic activity tends to decrease when trying to suppress the decomposition of alcohols, but the catalyst of the present invention maintains high activity and, in synergy with the addition of various third components, improves alkyl group selectivity and catalyst life. It is an excellent industrial catalyst that enables selective alkylation of phenols with a smaller unit of raw material than any existing catalyst. When carrying out the method of the present invention, the molar ratio of the phenolic compound and alcohol is 1:
A suitable ratio is 1 to 1:15, preferably 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. Further, at lower temperatures than this range, the reaction rate does not increase sufficiently, and under normal reaction conditions, the conversion rate of the reaction 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, an aqueous solution prepared by diluting 14.5 g of Water Glass No. 3 with 100 ml of pure water was added dropwise little by little. This silicon-containing manganese nitrate aqueous solution was diluted to 5,000 ml with pure water, and then ammonia water was added to form a silicon-containing manganese hydroxide precipitate, which was washed with water, filtered, and dried at 180°C for 8 hours. Crush the dried precipitate, add a small amount of water and mix thoroughly to make a powder with a diameter of 4.8
It was compression molded into a cylindrical pellet with a height of 3.2 mm. This shaped catalyst was pre-calcined at 500℃ for 15hrs, and further heated to 1050℃.
It was sintered by applying high temperature heat treatment at ℃ for 5 hours. This mixed sintered catalyst of manganese oxide and silicon oxide has Mn:
Spherical-like particles with a Si atomic ratio of 100:2 and a diameter of several μm were observed, and the surface area measured by the BET method was
It was 0.11m ² /g. 100 g of the catalyst thus prepared was packed into a stainless steel reaction tube with an inner diameter of 21 mm to form a reaction bed. The molar ratio of phenol, methanol and water is 1:
The reaction raw material solution prepared at 5:0.5 was vaporized through a vaporizer whose temperature was adjusted to 230°C, and then introduced at a rate of 35 g/hr into a reaction tube whose internal temperature was maintained at 425°C. The alkylation reaction was carried out by The reaction products were analyzed by gas chromatography. Table 1 shows the composition, surface area, and reaction results of the catalyst. Note that the methanol effective utilization rate is a value calculated using the following formula. Methanol effective utilization rate (%) = Produced o-cresol (mol) + Produced 2,6-xylenol (mol) x 2 / Reacted methanol (mol) x 100 Example 2 In Example 1, water glass No. 3 was used. A precipitated dry body of manganese hydroxide was obtained. next,
The dried product and tin oxalate were mixed together with an appropriate amount of water and dried again at 180° C. for 8 hours. (Mn:Sn=100:5 atomic ratio) Pulverize this,
Thereafter, compression molding and preliminary firing were carried out in the same manner as in Example 1, followed by heat treatment at 1000°C for 14 hours to obtain Mn-
A Sn-based high-temperature heat-treated catalyst was manufactured. An alkylation reaction of phenol with methanol was carried out under the same conditions as in Example 1, and the results shown in Table 1 were obtained. Example 3 In Example 1, after forming a precipitate of manganese hydroxide containing silica, calcium hydroxide powder was added, thoroughly mixed, washed with water, filtered,
It was dried at 180°C for 8 hours. (Mn:Si:Ca=100:
2:1 atomic ratio). This was crushed, made into cylindrical pellets in the same manner as in Example 1, pre-calcined, and further
A Mn--Si--Ca-based high-temperature heat-treated catalyst was produced by heat treatment at ℃ for 4 hours. An alkylation reaction of phenol with methanol was carried out under the same conditions as in Example 1, and the results shown in Table 1 were obtained. Example 4 The Mn-Si-Ca cylindrical pellet described in Example 3 was immersed in a 0.01N potassium hydroxide solution to prepare a catalyst modified with potassium, and heated at 500°C.
It was fired for 15 hours and then for 5 hours at 1050°C.
(Mn:Si:Ca:K=100:2:0.001 atomic ratio) An alkylation reaction of phenol with methanol was carried out under the same conditions as in Example 1, and the results shown in Table 1 were obtained. Comparative Examples 1 to 4 In Examples 1 to 4, the alkylation reaction of phenol was carried out in the same manner as in Example 1 using the system that had been subjected to only heat treatment at 500° C. for 15 hours as a catalyst. The results are shown in Table 2.

[Table] Comparative Examples 5 to 7 70% nitric acid aqueous solution 3 was added to 2000 g of manganese carbonate, dissolved, and then diluted with 0.5 g of water. Ammonia water was added to this manganese aqueous solution to form a precipitate, which was washed with water, filtered, and dried at 180°C for 8 hours. This was crushed into pieces with a diameter of 4.8m/m and a height of 4.8m/m.
The pellets were made into cylindrical pellets of 3.2 m/m and fired at 500°C for 5 hours, and then the firing temperature was changed to produce three types of catalysts with different firing temperatures () 700°C for 3 hours, ) 950°C for 3 hours.
Example 1
The reaction was carried out under the same conditions. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. A phenolic compound having at least one hydrogen atom at the ortho position and an alcohol,
In producing an orthoalkylated product of the phenolic compound by a gas phase catalytic reaction in the presence of a catalyst, manganese oxide and at least one component selected from the group consisting of a silicon oxide and tin oxide, and / or b A catalyst containing at least one component selected from the group consisting of calcium oxide and potassium oxide is heat-treated in the range of 1000° to 1500°C to sinter, and then used in the reaction. A method for highly selective orthoalkylation of phenolic compounds. 2. The method according to claim 1, wherein the heat treatment time is 3 to 96 hours.