JPH0120139B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for producing anthraquinones. More specifically, the present invention relates to a catalyst in a method for producing anthraquinone by oxidizing diphenylmethane in the gas phase with an oxygen-containing gas in the presence of a catalyst. Anthraquinone is an extremely useful compound as a synthetic intermediate for dyes or various organic compounds, and as a cooking aid for pulp production. As such an industrial method for producing anthraquinone, there is a catalytic air oxidation method for anthraquinone. This method has a high yield and can supply inexpensive anthraquinone, but since the raw material anthracene is obtained by refining it from coal tar, the refining cost is high, and furthermore, due to the decline of the coal industry, Its supply has become difficult. In addition, various methods have been proposed as methods for producing anthraquinone, the most representative of which is a method in which phthalic anhydride and benzene are reacted using aluminum chloride. In this method, anthraquinone can be obtained in almost quantitative yield, but expensive aluminum chloride is mixed with phthalic anhydride to produce
Since it is necessary to use more than double the mole, the cost of aluminum chloride exceeds the cost of raw materials.
This poses a difficulty in the industrial implementation of the method. Already, as a new method for producing anthraquinone,
A method of catalytic gas phase oxidation using diphenylmethanes as a starting material in the presence of a catalyst is disclosed. In this method, as a representative catalyst, a mixed catalyst material made by adding one or more of phosphorus pentoxide and alkali metal oxide to vanadium pentoxide has been proposed (Japanese Patent Application Laid-open No. 75568/1983). . However, even when these catalysts are used, the desired product has not yet been obtained in a sufficiently satisfactory yield. The inventors of the present invention have conducted intensive studies on a method for producing anthraquinone using diphenylmethane as a raw material. By using a catalyst containing molybdenum oxide and titanium oxide, the inventors have found that anthraquinone can be produced over a long period of time, producing an anthraquinone that has never been seen before. They discovered that anthraquinone can be obtained in a high yield and completed the present invention. That is, the present invention is a method for producing anthraquinone by catalytic gas phase oxidation of diphenylmethane with an oxygen-containing gas in the presence of a catalyst, which is characterized by using a catalyst containing molybdenum oxide and titanium oxide as the catalyst. It's a method. According to the method of the present invention, anthraquinone can be produced in a high yield, and since the production of phthalic anhydride as a by-product is extremely small, post-treatment of the product can also be carried out advantageously. The starting material used in the method of the present invention has the general formula () (In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, a formyl group, or a carboxyl group). Specifically, as diphenylmethanes, 2-
Methyldiphenylmethane, 2-ethyldiphenylmethane, 2-isopropyldiphenylmethane, 2
Examples include -tert-butyldiphenylmethane, 2-formyldiphenylmethane, and 0-benzylbenzoic acid. The catalyst used in the method of the invention contains molybdenum oxide and titanium oxide. The molybdenum oxide is usually molybdenum pentoxide, molybdenum trioxide, molybdenum dioxide, or the like. Further, as the titanium oxide, titanium dioxide is usually frequently used. The catalyst used in the method of the present invention contains molybdenum oxide and titanium oxide as main components, but may further contain other third components. In particular, oxides of calcium, antimony, bismuth, chromium, manganese, iron, cobalt or nickel can be mentioned as third components which do not reduce the effectiveness of the method of the invention, but rather have a positive effect. These may contain one type or two or more types. In the catalyst used in the method of the present invention, the content ratio of molybdenum oxide, titanium oxide, and metal oxide as a third component added if necessary is Mo:Ti:Element as the third component in an atomic ratio. 0.8~2.0:
5-25: 0.1-1.2, especially 1.0-1.8: 8-20:
0.2-1.0 is preferred. As a method for preparing the catalyst, a known method for preparing metal oxide catalysts can be applied. Examples include precipitation method, gelation method, and impregnation method. In order to prepare the catalyst, in addition to the oxides of the metal elements mentioned above, acids, bases or salts, such as carbonates, bicarbonates, chlorides or nitrates, can be added during the preparation of the catalyst (calcination) or during the reaction. Compounds that convert to oxides are used. Such compounds include, for example, molybdic acid, ammonium molybdate, ammonium paramolybdate, calcium acetate,
Stannous chloride, antimony trichloride, bismuth nitrate,
Compounds such as chromic anhydride, ferric chloride, cobalt nitrate or nickel nitrate may be mentioned. The catalyst used may be a supported catalyst in which the above catalyst components are supported on a carrier, and in this case, the carrier may be a commonly used catalyst such as alumina, silica-alumina, silica, carborundum, steatite, etc. A carrier can be applied. The catalyst is generally dried at a temperature of 150° C. or lower, or further calcined at a temperature of about 300 to 700° C., and then used after being shaped by crushing, sieving, tablet molding, or the like. Therefore, catalysts prepared by using compounds other than the oxides mentioned above and molded only by drying,
Alternatively, if the calcination is insufficient, the catalyst contains something other than the oxide of the component element, but the method of the present invention can be effectively carried out even with such a catalyst. As the oxygen-containing gas used in the method of the present invention, air is generally used, but a mixed gas of oxygen and an inert gas such as nitrogen, carbon dioxide, or steam can also be used. The reaction temperature at which the process of the invention is carried out is generally
It is in the range of 200-700°C, preferably 250-500°C. In addition, the gas concentration of diphenylmethane, which is the raw material supplied, is 25 to 100 when using air.
Air/g feed, preferably 25-50 air/g feed. Also, the space velocity is 500 to 10000Hr ^-1 ,
Preferably it is 1000 to 6000 Hr ^-1 . Normal pressure is often used as the pressure during the reaction, but it may also be under reduced pressure or increased pressure. The reactor outlet gas is cooled to precipitate the produced anthraquinone as a solid. The precipitated solid has a high degree of purity even as it is, and the target product of high purity can be easily obtained by conventional methods such as sublimation, distillation, etc., or washing with an appropriate solvent. The present invention will be explained below with reference to Examples. Example 1 13.1 g of ammonium molybdate was dissolved in 40 g of water, then 5.9 g of chromic anhydride was added and dissolved, and further 84.8 g of titanium dioxide (anatase type)
was added to make a uniform paste. Norton fused alumina (SA-101, 16~
30 mesh) was placed in a 300 ml beaker, and the carrier particles were heated to 120-130°C, then the above paste was added little by little and baked uniformly on the surface of the carrier at the same temperature. After addition and coating, heating and stirring were continued to dry at 120 to 130°C for about 40 minutes. The carrier coated with the active ingredient was then calcined in an electric furnace at 450° C. for 4 hours in an air atmosphere. Fill a quartz reaction tube (25 mmφ x 500 mm) with 30 ml of the catalyst prepared in this way, use 2-methyldiphenylmethane as the raw material, gas concentration 670 - air/g raw material, space velocity 3000 hr ^-1 , catalyst temperature 380 ~
The reaction was carried out under conditions of 420°C, and the target anthraquinone (pale yellow mp 284-286°C) was obtained in a yield of 78.4%. The anthraquinone produced was highly pure even in its original state. Examples 2 to 10 Table 1 shows the results obtained by using the same method as in Example 1 but only changing the catalyst. However, the atomic ratio of Mo:Ti:third additive element is 1.4:10:0.6.

[Table] Examples 11 to 21 Reactions were carried out using the same catalytic method as in Example 1 and using various starting materials. The results are shown in Table-2.

【table】

Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, a formyl group, or a carboxyl group.) When producing anthraquinone by catalytic gas phase oxidation of diphenylmethanes represented by the following formula with an oxygen-containing gas in the presence of a catalyst: , a method for producing anthraquinone, characterized in that a catalyst containing molybdenum oxide and titanium oxide is used as a catalyst. 2. The catalyst contains molybdenum oxides, titanium oxides, and oxides of at least one element selected from the group consisting of calcium, tin, antimony, bismuth, chromium, manganese, iron, cobalt, and nickel. A method according to claim 1.