JPH07206736A - Oxidation of hydrocarbon - Google Patents

Abstract

PURPOSE:To provide a method for economically oxidizing a hydrocarbon by hydrogen peroxide so as to obtain the aimed product in high yield by using a new catalyst, a mordenite containing titanium in its crystal skeleton. CONSTITUTION:A hydrocarbon is oxidized by hydrogen peroxide in the presence of a catalyst, a mordenite containing titanium in its crystal skeleton. In this case, the titanium content of the catalyst is pref. 0.01-1.5mg atom per g of the catalyst. Besides, it is preferable that the atom ratio Si/Al in this catalyst be 30-500. Using this method, phenol or hydroquinone can be synthesized from benzene, the corresponding alkylene oxide from an olefin, and the corresponding alcohol or aldehyde from a paraffin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation method for oxidizing a hydrocarbon with hydrogen peroxide in the presence of a catalyst. More specifically, it relates to the oxidation method using a new catalyst, mordenite, containing titanium in the crystal skeleton as a catalyst.

[0002]

2. Description of the Related Art Conventionally, silicalite containing titanium in a crystal skeleton, that is, titanium silicalite (TS-1), prepared by hydrothermal treatment of a mixture of a silicon oxide source, a titanium oxide source and water, has been known. It is known to be used as a catalyst for various reactions such as alkylation, disproportionation, hydrogenolysis, isomerization and oxidation (Japanese Patent Publication No. 1-2889). It is also known that TS-1 is used as a catalyst when epoxidizing an olefin with hydrogen peroxide (Japanese Patent Publication No. 4-5028). However, the TS-1 catalyst has a relatively small pore inlet diameter (5.3 × 5.6Å) and is slightly larger than the benzene molecule. For example, aromatic hydrocarbons are hydroxylated with hydrogen peroxide. As a catalyst in this case, the diffusion of the reactants and products into the pores and the outflow from the pores are slow, so that the catalytic activity cannot be satisfactorily exhibited and the yield of the target product is low. . In addition, since the catalytic activity of this TS-1 catalyst is greatly affected by the presence of an alkali metal as an impurity, it is necessary to use an extremely high-purity raw material containing no alkali metal in the preparation thereof.
There is also a problem in terms of economy.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to improve the problems of the conventional TS-1 catalysts as described above, such as T
It is an object of the present invention to develop a new catalyst that replaces the S-1 catalyst, and to provide an economical method of oxidizing a hydrocarbon with hydrogen peroxide, which uses the catalyst and has a high yield of a target substance.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that mordenite crystals having a pore inlet diameter (6.5 × 7.0Å) larger than that of TS-1. We succeeded in incorporating a proper amount of titanium in the skeleton, and the mordenite containing titanium in the crystal skeleton was introduced into the pores of the reactant during hydroxylation of aromatic hydrocarbons with hydrogen peroxide. It has been found that the diffusion rate of OH is high, and that it exhibits excellent catalytic activity, and that it also exhibits excellent catalytic activity when epoxidizing olefins with hydrogen peroxide and oxidizing hydrocarbons with hydrogen peroxide. Completed the invention. In addition, the inventors of the present invention have shown that titanium which is simply dispersed and supported on mordenite and which is not contained in the crystal skeleton, such as those prepared by an impregnation method, does not exhibit the desired catalytic activity, and In conventional normal hydrothermal synthesis, that is, by treating the mordenite and the titanium source at high temperature and high pressure in the presence of water,
It has been confirmed that almost no titanium can be contained in the crystal skeleton of mordenite.

Accordingly, the gist of the present invention is to use a mordenite containing titanium in the crystal skeleton as a catalyst when oxidizing a hydrocarbon with hydrogen peroxide in the presence of a catalyst. Exist in.

The present invention will be described in detail below. The catalyst used in the present invention contains titanium in the crystal skeleton of mordenite, and no such catalyst has been proposed so far. The catalyst used in the present invention can be generally prepared from mordenite and a titanium introduction source as follows.

As the mordenite for preparing the catalyst, generally, commercially available products can be widely used. In addition, titanium tetrachloride is generally used as a source for introducing titanium into the crystal skeleton of mordenite, and titanium tetrachloride can be used as it is or used as a solution having a concentration of 20% by weight or more using ethanol as a solvent. You can also In preparing the catalyst, the Si / Al atomic ratio of commercially available mordenite is 5, but generally, one having a higher Si / Al atomic ratio is desired. The Si / Al atomic ratio is 30
The dealumination treatment is performed so as to be about 500, preferably 50 to 300. As the method of dealumination treatment, for example, (a) a method of firing at 500 to 800 ° C. for 5 to 10 hours, (b) a method of 5 to 8N in a nitric acid aqueous solution,
A method of heating for 20 hours, or (c) a method of using the methods (a) and (b) together is adopted. Thus, increasing the Si / Al atomic ratio increases the hydrophobicity,
The target oxidation reaction easily proceeds, and titanium is easily introduced. Then, the dealuminated mordenite is generally contacted with an inert gas such as helium gas or nitrogen gas containing titanium tetrachloride by passing it through titanium tetrachloride or a solution thereof at room temperature, and The catalyst is prepared by heating at a temperature, for example, room temperature to 650 ° C., preferably 350 to 450 ° C., for 0.5 to 6 hours, preferably 0.5 to 2 hours, and then cooling, washing with water, and drying. It can be carried out. Also,
When preparing the catalyst, the amount of titanium tetrachloride used is the above Si /
Al atomic ratio of 0.05 per 1 g of prepared mordenite
.About.15 milligram atoms, preferably 0.1 to 10 milligram atoms are suitable.

The catalyst prepared as described above and preferably used in the present invention generally has a titanium content of 0.01 to 1.5 mg / g of the catalyst, preferably 0.1 to 1. It is 0 milligram atom. If the titanium content is less than 0.01 milligram atom or more than 1.5 milligram atom, the expected catalytic activity will be reduced.

An example of hydrocarbon oxidation to which the present invention can be preferably applied is as follows. In addition, the term "oxidation" in the present invention is used in a broad sense, such as
That is, the term includes introduction of phenolic hydroxyl group or introduction of alcoholic hydroxyl group, epoxidation, and aldehyde formation.

(1) Oxidation example of aromatic hydrocarbon Synthesis of phenol and hydroquinone by oxidizing benzene with hydrogen peroxide. Oxidizing alkylbenzene having an alkyl group having 1 to 4 carbon atoms with hydrogen peroxide,
Synthesis of alkylphenol corresponding to the raw material alkylbenzene. (2) Oxidation example of olefin Synthesis of alkylene oxide corresponding to a raw material olefin by oxidizing an olefin having 2 to 10 carbon atoms with hydrogen peroxide. (3) Paraffin Oxidation Example A paraffin having 3 to 10 carbon atoms is oxidized with hydrogen peroxide to synthesize an alcohol and an aldehyde corresponding to the raw paraffin.

The oxidation method of the present invention is performed as follows. The reaction is usually carried out in a liquid phase because an aqueous hydrogen peroxide solution is used, but a mixed phase may be used when a gas phase hydrocarbon is used. The reaction mode may be either a batch system or a continuous system. The reaction temperature is usually 20 to 100 ° C., and the reaction time is 0.5 to 5 hours. The reaction pressure is not particularly limited as long as the hydrocarbon is absorbed or liquefied in the liquid phase at the reaction temperature. The weight ratio of hydrocarbon to catalyst is preferably 0.005 to 200, and particularly preferably 0.05 to 100. The molar ratio of hydrocarbon to hydrogen peroxide is preferably 0.001 to 200, and particularly preferably 0.01 to 100.

[0012]

EXAMPLES The present invention will be described in more detail below with reference to Reference Examples, Examples and Comparative Examples.

Reference Example 1 (Preparation of catalyst) Commercially available mordenite (manufactured by Toso Corporation; Si / Al atomic ratio =)
5) 10 g was put in an electric furnace and baked in air at 700 ° C. for 5 hours, then cooled, placed in a 100 ml flask, 30 ml of 6N nitric acid aqueous solution was added, a condenser was attached, and the mixture was put on a hot water bath for 5 hours. Heated for hours. Then, it was thoroughly washed with pure water at room temperature and dried. Si /
A dealuminated mordenite having an Al atomic ratio of 96 was obtained.

3 g of the dealuminated mordenite was placed in a quartz reaction tube and treated in a helium stream at 500 ° C. for 4 hours to be sufficiently dried. After cooling the reaction tube to room temperature, while continuously feeding the helium gas that has passed through the container containing titanium tetrachloride into the reaction tube,
Heated for 1 hour. After that, helium gas was allowed to flow at the same temperature for 1 hour to purge unadsorbed TiCl ₄ remaining in the reaction tube, then cooled to room temperature while continuing to flow helium gas, taken out, and repeatedly washed with pure water. It was dried at 130 ° C. The total amount of titanium in the titanium-containing mordenite (catalyst A) thus obtained was 0.30 mg / g per 1 g as determined by atomic absorption after dissolving with hydrofluoric acid. When the infrared spectrum of the catalyst A was measured, an absorption band due to Si—O—Ti stretching vibration was found at 960 cm ⁻¹ . Further, when the X-ray diffraction spectrum of the catalyst A was measured, no diffraction based on TiO ₂ (anatase) was found. This indicates that Ti ⁴⁺ is not present as TiO ₂ particles but is incorporated in the mordenite skeleton.

Example 1 In a 100 ml flask equipped with a condenser, 20 ml of toluene, 5 ml of water and 4.7 mmol of hydrogen peroxide (35
% Aqueous solution) and 0.25 g of catalyst A were added, and the mixture was reacted on a hot water bath at 90 ° C. for 2 hours while stirring with a magnetic stirrer. After the reaction, the conversion of hydrogen peroxide was determined by iodine titration, and the products were analyzed by gas chromatography. The results are shown in Table 1.

Example 2 By the same treatment as in Reference Example 1, Si / Al atomic ratio = 13
Using the dealuminated mordenite of No. 3, mordenite containing 0.34 mg of titanium atom / g (catalyst B) was prepared, and the same experiment as in Example 1 was conducted using this catalyst B. The results are shown in Table 1.

Comparative Example 1 Titanium prepared by hydrothermal synthesis using an autoclave using tetraethyl orthosilicate, tetraethyl titanate and tetrapropylammonium hydroxide containing no alkali metal as raw materials in accordance with JP-B-1-42889. The same experiment as in Example 1 was conducted using silicalite (TS-1) (catalyst C). The results are shown in Table 1.

In this comparative example, the catalyst C used had a higher titanium content than the catalysts A and B used in the examples, and the conversion rate of hydrogen peroxide was high, but the amount of cresol produced was higher than that in the examples. Much less and less selective.

Comparative Example 2 Titanium sulphate (Ti (SO ₄ ) ₂ ) aqueous solution was added to dealuminated mordenite (Si / Al atomic ratio = 96), which is the raw material of catalyst A used in Example 1, by the impregnation method. Supported mordenite supporting titanium (catalyst D)
Was prepared. An experiment was conducted in the same manner as in Example 1 using this catalyst D. In this comparative example, the amount of catalyst used in the reaction was set so that the amount of titanium was the same as in Example 1. The results are shown in Table 1.

The catalyst D used in this comparative example showed almost no desired catalytic activity.

[0021]

[Table 1]

Example 3 In a 50 ml pressure-resistant glass autoclave, catalyst A0.5 was added.
g, 39.6 mmol of hydrogen peroxide, 22 g of isopropyl alcohol as a solvent, and 2 g of a 1 wt% sodium dihydrogen pyrophosphate aqueous solution as a stabilizer of hydrogen peroxide, and propylene was supplied to this at a pressure of 5 kg / cm ^2. The reaction was carried out at a reaction temperature of 70 ° C. for 4 hours. As a result, the conversion of hydrogen peroxide was 70%, and the selectivities of propylene oxide and propylene glycol were 90% and 5%, respectively.

[0023]

According to the present invention, the catalytic activity of the catalyst is excellent, and the target product can be obtained in a high yield in the oxidation of hydrocarbons, especially aromatic hydrocarbons with hydrogen peroxide. Further, the catalyst used in the present invention does not need to be highly pure as a raw material for preparation, and thus can be economically prepared.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C07B 41/00 7419-4H C07C 29/03 31/20 Z 9159-4H 37/60 39/07 45 / 28 47/54 C07D 301/12 // C07B 61/00 300

Claims (3)

[Claims] 1. A method for oxidizing a hydrocarbon, which comprises using mordenite containing titanium in a crystal skeleton as a catalyst when oxidizing a hydrocarbon with hydrogen peroxide in the presence of a catalyst. 2. The method for oxidizing a hydrocarbon according to claim 1, wherein the content of titanium in the mordenite containing titanium in the crystal skeleton used as the catalyst is 0.01 to 1.5 mg / g of the catalyst. 3. The Si / Al atomic ratio of mordenite containing titanium in the crystal skeleton used as a catalyst is 30 to 50.
The method for oxidizing a hydrocarbon according to claim 1, wherein the method is 0.