JPS6267038A - Production of phenol - Google Patents

Abstract

PURPOSE:To obtain a phenol from an aromatic compound directly in one stage and in high yield, by subjecting an aromatic compound and nitric acid to a gaseous-phase contact reaction in the presence of a catalyst. CONSTITUTION:An aromatic compound such as benzene, naphthalene, etc., which may contain a substituent group and preferably >=2 mol based on 1 mol of the compound of nitric acid are subjected to a gaseous phase contact reaction in the presence of an oxidation catalyst containing vanadium oxide or molybdenum oxide at 200-500 deg.C, preferably 250-450 deg.C preferably in coexistence of water, to give a phenol corresponding to the above-mentioned raw material from the inexpensive raw material by one stage in high yield, in good selectivity and in high purity while suppressing formation of by products. The nitric acid is preferably used as 0.1-60wt.% aqueous solution and nitrogen dioxide and water prepared as by-products are reacted with oxygen or an oxygen-containing gas such as air, etc., and can be reused as nitric acid.

Description

[Detailed description of the invention] (Field of academic use) The present invention relates to a novel method for producing phenols.

More specifically, by reacting an aromatic compound with nitric acid, A
Fe/ roH (Ar is an aromatic residue)
The present invention relates to a method for producing mols.

(Prior Art) Conventionally, methods for producing phenols include (1) a method for producing phenol by oxidizing benzene with oxygen in the gas phase in the presence of a catalyst (Japanese Patent Application Laid-open No. 87527/1983);
(2) A method for producing phenol by reacting benzene with nitrous oxide in the presence of a catalyst (catalyst, 103.
276 (1982)) etc. are known.

However, in these methods, the yield is about 25% in method (1), and about 5% in method (2), which is quite low. The manufacturing method has not yet been industrialized.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for directly producing phenols from aromatic compounds in one step and in high yield.

(Means for Solving the Problem) As a result of various studies regarding the above-mentioned purpose, the present inventors unexpectedly found that by using benzene as an oxidizing agent, nitric acid was used instead of the conventionally used oxygen or nitrous oxide. discovered that phenol could be obtained in high yield, and completed the present invention.

That is, in the present invention, an aromatic compound and nitric acid are used as raw materials and subjected to a gas phase catalytic reaction in the presence of a catalyst.

The reaction is thought to proceed, for example, as shown in the following equation.

C,H6+ 2HNO,-+ C,H,OH+ 2NO
, +H,0 The aromatic compound used as a raw material in the method of the present invention is a compound such as benzene or naphthalene, which may be unsubstituted or have a substituent. For example, benzene, toluene, 0-lm- or 1tp- Examples include various aromatic compounds such as xylene, mesitylene, cumene, biphenyl, phenol, ethylbenzene, naphthalene, α-methylnaphthalene, and β-methylnaphthalene.

Further, the nitric acid used in the method of the present invention is fuming nitric acid, 1
Nitric acid, nitric acid aqueous solution, or nitric anhydride, that is, dinitrogen pentoxide. Usually, an aqueous solution is most desirable, and its concentration is not particularly limited, but a 0.1-60% nitric acid aqueous solution is preferred. Further, since nitric acid is an aqueous solution of dinitrogen pentoxide, dinitrogen pentoxide may be used in place of nitric acid in coexistence with water. Furthermore, water may be added directly to the reaction atmosphere separately from nitric acid.

In order to convert all aromatic compounds into corresponding phenols, the amount of aromatic compounds and nitric acid to be used is 2 moles or more of nitric acid per 1 mole of aromatic compounds, as shown in the above formula. It is desirable to do so. However, it is not particularly limited.

The catalyst used in the method of the invention is an oxidation catalyst. Examples of such oxidation catalysts include catalysts used for oxidation reactions of aromatic compounds listed on pages 46-47 of Catalyst Classification Table 1 by Reaction (edited by Tarama Laboratory, Kyoto University, published by Kagaku Kogyosha). It will be done. Specifically, vanadium, molybdenum,
oxides of elements selected from the group consisting of bismuth, tungsten, chromium, cobalt, iron, nickel, titanium, lead, silver, platinum, palladium, phosphorus, manganese and copper;
It is a catalyst containing an organic acid salt or at least one metal selected from the group consisting of silver, platinum, and palladium. For example, oxides such as cobalt oxide, nickel oxide, titanium oxide, lead oxide, iron oxide, copper oxide, chromium oxide, vanadium oxide, molybdenum oxide, zinc oxide, bismuth oxide, tungsten oxide, or cerium molybutate, naphthene, etc. Cobalt acid, cobalt oleate, cobalt fucurate, cobalt tolylate, cobalt stearate, cobalt acetate, manganese rosin acid, manganese naphthenate, tin vanadate, copper vanadate, manganese acetate, and these can be used alone or in two types. It is also possible to use a mixture of the above. Further, metals such as silver, platinum, and palladium are used alone or in combination. These oxides or metals may be supported on a carrier. As the carrier, one or more of those commonly used as catalyst carriers can be used, such as silica, alumina, silica-alumina, zeolite, diatomaceous earth, activated clay, titanium oxide, magnesium oxide, zinc oxide, and boron oxide. .

Among the above catalysts, vanadium oxide,
A catalyst containing molybdenum oxide.

Catalysts containing oxides can be prepared by conventional methods. For example, according to the immersion method, salts containing the metals constituting these oxides are dissolved in water, and a support such as silica or alumina is immersed in the aqueous solution, followed by drying and thermal decomposition. Manufacture. Further, for example, according to a precipitation method, a carrier such as silica or alumina is added to an aqueous solution of a salt containing a metal constituting these oxides, and an alkali substance is added while stirring to form a precipitate. It is prepared by filtering, washing, drying and calcining the precipitate. In addition, there are various catalyst preparation methods, and there are no limitations on the catalyst preparation method.

Further, in the above catalyst, there is no particular restriction on the amount of the catalyst component supported on the carrier, and it is generally sufficient to support an appropriate amount depending on the carrier. Generally, a loading of less than 0.001% to 100% is sufficient. Of course, the catalyst component may be used without being supported on a carrier.

In the method of the present invention, the reaction atmosphere is not particularly limited, and may be an inert gas atmosphere, an active gas atmosphere, or a reducing gas atmosphere.

Inert gases include nitrogen, helium, argon, etc.
Further, examples of the active gas include nitrogen oxides. These inert gases and active gases may be used in combination.

Further, examples of the reducing gas include hydrogen, ammonia, hydrazine, and carbon oxide. These reducing gases may be mixed with an inert gas.

In the method of the present invention, the reaction temperature is 200 to 500°C,
Preferably it is in the range of 250 to 450°C. If the temperature is lower than 200°C, the yield of phenols will be insufficient, and if the temperature exceeds 500°C, the yield of phenols will decrease and by-products will be produced, which is not preferable.

The method of the invention can be carried out in the gas phase.

That is, it can be carried out in a fixed bed, fluidized bed or moving bed reactor. It can also be carried out by heating vapors of an aromatic compound and nitric acid in the presence of the catalyst material in a reactor or reaction tube.

At this time, by adding water or steam to the raw material vapor, phenols can be obtained in a higher yield and more safely.

In the method of the present invention, the desired phenols can be easily separated and purified from the reaction product by an appropriate method, for example, a conventional method such as distillation.

In the method of the present invention, the by-product nitrogen dioxide and water can be used again as nitric acid by reacting with oxygen or an oxygen-containing gas such as air.

By the method of the present invention, phenols corresponding to the raw aromatic compounds, such as phenol, 〇-cresol, m
-Cresol, p-cresol cresols, 2.5
-Xylenol, α-
Naphthols such as naphthol and β-naphthol can be obtained.

(Functions and Effects) Corresponding phenols can be produced by subjecting an aromatic compound and nitric acid to a gas phase contact reaction in the presence of a catalyst.

This method has the following advantages. First, when trying to produce benzene using this method, very cheap benzene can be used as a raw material. Second, phenols can be produced from raw materials in one step. Thirdly, the yield of phenols is high. Fourthly, there are few by-products, the selectivity is good, and therefore highly pure phenols can be obtained.

Fifth, by-product nitrogen dioxide and water can be reacted with an oxygen-containing gas to form nitric acid, which can be reused.

That is, the present invention provides a novel reaction as a method for producing phenols, and also provides a method that can be carried out industrially advantageously.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 V2 by dipping method of granular ammonium metavanadate
O, /Sin□catalyst ("205 content 5%) 50+++
4' was packed into a Pyrex glass flow-through reactor having an inner diameter of 2511 m. The front part of this reactor is connected to a raw material insertion pipe and a gas introduction pipe to constitute a raw material vaporization part, and the rear part is connected to a receiver via an air cooling part. In the reaction section, the internal temperature of the reactor was maintained at 350°C, the liquid hourly space velocity was 0.11/l-catalyst/hr, and 0.78 # (Of) 1 mol of benzene) and 4.2 g (0.0 , 02 mol) were separately inserted from the raw material insertion tube, and at the same time, 10 times the mole of nitrogen relative to the raw material benzene was passed under normal pressure.

When the reaction product passed through the reactor and was condensed was analyzed by gas chromatography, 0.44g of phenol was produced, and the conversion of benzene was 51.8%, the selectivity was 90.6%, and the yield was 46.9%. A small amount of nitrobenzene was obtained as a by-product.

Examples 2 to 14 In Example 1, the catalysts shown in Table 1 were used instead of ■, ○, /Sin, and the reaction temperature was 350°C,
Table 1 shows the results of a reaction carried out in the same manner as in Example 1 using the same reaction apparatus as in Example 1.

Example 15 In Example 1, 0.92 g (0.01 mol) of toluene was used instead of benzene as the raw material, and the reaction temperature was 325 mol.
℃, and in the same reaction apparatus as in Example 1, the reaction was carried out in the same manner as in Example 1. As a result, 0-cresol, m
047 g of a mixture of -cresol and p-cresol was obtained. The conversion rate of toluene was 50.7%, and the selectivity of cresols was 856%.

Example 16 In Example 1, 1.069 (0.01 mol) of p-xylene was used instead of benzene as the raw material, the reaction temperature was set to 330°C, and Example 1 was carried out using the same reaction apparatus as Example 1.
The reaction was carried out in the same manner. As a result, 0.49 g of 2.5-xylenol was obtained. Conversion rate of p-xylene 48.
The selectivity for 2,5-xylenol was 82.4%.

Example 17 In Example 1, 1.06.9 (0.01 mol) of m-xylene was used instead of benzene as the raw material, the reaction temperature was set to 330°C, and the same reaction apparatus as in Example 1 was used. The reaction was carried out in the same manner as in Example 1. the result.

2,6-xylenol, 2,4-xylenol and 3
．． A mixture of 5-xylenol was obtained.

The conversion rate of m-xylene was 490%, and the selectivity of xylenol was 862%.

Example 18 In Example 1, 1.06.9 (0.01 mol) of 0-xylene was used instead of benzene as the raw material, the reaction temperature was set to 330°C, and the reaction was carried out in the same reaction apparatus as in Example 1. The reaction was carried out in the same manner as in Example 1. As a result, a mixture of 2,3-xylenol and 6,4-xylenol 0.5
1g was obtained. The conversion rate of 0-xylene was 501%, and the selectivity of xylenol was 864%.

Example 19 Granular V2O,-M prepared by ammonium mekhanadinoate and ammonium molybdate dipping method
5 omt of oO3/Sin, catalyst (V2O, content 5%, Mob, fi-5%) was packed into a flow-through reactor made of Pyrex glass with an inner diameter of 25 mm. The front part of this reactor is connected to a raw material insertion pipe and a gas introduction pipe to constitute a raw material vaporization part, and the rear part is connected to a receiver via an air cooling part. In the reaction section, the internal temperature of the reactor was maintained at 400°C, the liquid hourly space velocity was 0.11/l-catalyst/hr, and benzene 0.78g (0.0
, 0.01 mol) and 4.2 g (0.02 mol) of a 30 polynitric acid aqueous solution were separately inserted from the raw material insertion tube, and at the same time, 10 times the mole of hydrogen relative to the raw material benzene was passed under normal pressure.

The reaction product passed through the reactor and condensed was analyzed by gas chromatography, and as a result, phenol was obtained with a benzene conversion rate of 918% and a selectivity of 8'54%.

Claims (1)

[Scope of Claims] 1) A method for producing phenols, which comprises subjecting an aromatized product and nitric acid to a gas phase catalytic reaction in the presence of a catalyst. 2) The method according to claim 1, wherein the gas phase catalytic reaction is carried out in the presence of water.