Such silicate catalyst and the method of obtaining a mixture of alcohols and ketones

 

(57) Abstract:

Usage: the oxidation of saturated or alkylaromatic hydrocarbons with long alkyl chains C3-C12the mixture of alcohols and ketones, such silicate catalyst for oxidation of hydrocarbons. The essence of the invention: a catalyst for the oxidation of saturated hydrocarbons, C3-C12use oxides total f-crystals (TiO2)x(SiO2)1-xwhere X has a value of from 0.0001 to 0.04, the catalyst with the absorption band in the infrared spectrum in the region of 950 cm-1and as the oxidant used hydrogen peroxide or an aqueous solution. The oxidation is carried out at 50 to 150C in liquid or vapor phase, in the environment of the polar organic solvent soluble in water. 2 C. and 7 C.p. f-crystals, 4 PL.

The invention relates to the oxidation of saturated hydrocarbons, in particular to the use of a specific catalyst system, which, it has been found that allows selective oxidation of aliphatic compounds and iclilorovinyl aliphatic compounds.

Know the use of such silicalite catalyst for the controlled oxidation of saturated ogrzewania acid. In particular, it is known that synthetic silicic zeolite containing titanium atoms, promotes the reaction of the saturated hydrocarbon groups with hydrogen peroxide or organic peroxides according to the reaction principle of heterogeneous catalysis - output selectively alcohols and ketones.

These catalysts based on crystalline synthetic materials consisting of oxides of silicon and titanium and is characterized by the absorption band around 950 cm-1in the infrared region. They portrayed the General formula

x TiO2(1-x) SiO2where x is 0.0001 to 0.04).

They are the typical way of a mixture containing a source of silicon oxide, titanium oxide, nitrogen-containing organic base and water, or dealuminated ZSM-5 and the reaction of vaporous titanium tetrachloride. The catalyst may contain small amounts of other metals, such as aluminum, gallium and iron.

This invention relates to the use of the above catalyst to obtain a mixture of alcohols and ketones by oxidation of saturated or alkylaromatic hydrocarbons.

These catalysts can be prepared according to the scheme: i) heating of the reaction mixture and is consequently the source of alkali metal,

d) nitrogen-containing organic base and

f) water

ii) isolation of the formed crystals from the reaction mixture and

(iii) annealing the selected crystals with the formation of the catalyst.

The catalyst may be agglomerated with the formation of crystalline groups, which are also active and quickly regenerated after the reaction of oxidation.

The invention also concerns a method for the oxidation of saturated or alkylaromatic hydrocarbons by the action of such compounds oxidizing agents in the presence of a heterogeneous catalyst and a solvent under heating and under atmospheric or increased pressure.

The method differs in that the oxidation is subjected to saturated hydrocarbon composition WITH5-C10or alkyl chain length of C3-C12in molecules of alkylaromatic hydrocarbons. The invention provides for the use of such silicalite a catalyst having an absorption band in the infrared region of about 950 cm-1.

A typical General formula catalyst

x TiO2(1-x) SiO2where x has a value of from 0.0001 to 0.04.

The catalyst used in Dan, the titanium oxide, and alkali metal oxide, nitrogen-containing organic base and water, while the molar ratio of the reactants in the composition corresponded to previously defined.

The source of oxide of silicon may be tetrachlorosilane, mainly tetraethylorthosilicate or simply silica in colloidal form or silicate of an alkali metal, preferably sodium or potassium.

Source of titanium oxide is capable of hydrolysis of a compound of titanium, mainly selected from TiOCl4, TiOCl2and Ti(alkoxy)4preferably Ti(OC2H5)4.

The organic base is a hydroxide of tetraalkylammonium, in particular the hydroxide of tetrapropylammonium.

To obtain catalyst a mixture of these reagents is subjected to hydrothermal effects in an autoclave at 130-200aboutWith, and the pressure of the mixture within 1-30 days, mainly 6-30 days until crystals are formed product, preceding the formation of the catalyst. Distinguish them from the mother liquor, washed thoroughly with water and dried. In the anhydrous state, they have the following composition:

HCO2(1-x)SiO20,04 (RN+)2O.

aboutWith, preferably about 175aboutWith over 1 to 30 days, preferably about 10 days. The resulting crystals are separated from the mother liquor, washed with water, dried and finally calcined. The calcination can be carried out at 200-600aboutWith, preferably at 550aboutWith over 20 am

The resulting catalyst has the following composition:

x TiO2(1-x) SiO2where x has the meaning indicated previously.

Offer molar ratio of the various reactants towards the source of silicon oxide (SiO2) are given in table. 1.

The catalyst may also contain cations of alkali metals M+where M is sodium or potassium, and in this case, it is desirable that the molar ratio of M+: SiO2had a value of from 0.001 to 0.5, selecting certain conditions, it is possible to carry out the oxidation of saturated compounds with a high degree of selectivity to alcohols and ketones under mild reaction conditions. One of the most useful applications of the reaction is the oxidation of linear and branched paraffins in the secondary alcohols and ketones. The process is especially valuable for compounds with a low number of carbon at which svojstva isopropyl alcohol, acetone, secondary butyl alcohol and methyl ethyl ketone. Aliphatic substituted compounds may be part of the common aliphatic compounds or aryl compound (alkylaromatic). In addition, these compounds may contain other functional groups, which are electron-repelling properties and which, accordingly, are not active.

Reactivity of aliphatic compounds is slowed down during the transition from tertiary to secondary and then to the primary connection.

The particular advantage of this invention is that the process uses mild conditions of temperature and pressure at high conversion and yield and low resultant by-product. In particular, the conversion of hydrogen peroxide is high. The optimum reaction temperature between 50 and 150aboutWith primarily about 100aboutC. the Pressure should be such that all materials are in liquid or condensed (condensed) phase. The reaction can be conducted at room temperature, but higher reaction rate requires a higher temperature, for example under conditions of fractionation with delegacia. May be the pressure at an even higher temperature. The use of higher pressures in the range from 1 to 100 bar (105-107PA) leads to higher conversion and selectivity of the reaction.

The oxidation reaction may be conducted in periodic mode or in a fixed bed, and the use of heterogeneous catalyst creates conditions for continuous reaction in single-phase or two-phase system. The catalyst under the reaction conditions remain stable, it can be fully recycled and reused.

In accordance with this invention the process is carried out preferably in the presence of a solvent. The choice of solvent is important because it must combine the organic phase and the aqueous phase, which mainly is due to the use of an aqueous solution of hydrogen peroxide as oxidizing agent. Are preferably polar compounds, examples of solvents are alcohols, ketones, esters, glycols and acids with a not too high number of carbon atoms, predominantly less than or equal to six. From the most preferred alcohols are methanol or tertiary butanol, ketones such as acetone, acetic acid or propionic. It is important and the amount of solvent, ISAT from oxidizable material, for example it is established that the oxidation of normal hexane aqueous solution of hydrogen peroxide yield is improved when the ratio of acetone to hexane lies in the range from 1:1 to 4:1. The solvent improves the Miscibility of the hydrocarbon phase and the aqueous phase, which mainly is due to the use of an aqueous solution of hydrogen peroxide as oxidizing agent.

The preparation of the catalyst.

15 g of tetraethylorthosilicate (available from Aldrich Chemical Company) is slowly added dropwise to 250 ml of distilled water, so that started the hydrolysis. The resulting white suspension is cooled to 2aboutWith, then add 180 ml of hydrogen peroxide solution in water concentration of 30 wt. with constant cooling of the mixture to 2aboutC. the Mixture was stirred at this low temperature for 2 hours Then add 250 ml of an aqueous solution of hydroxide of tetrapropylammonium concentration of 25 wt. (with the trademark Alfa concentration of 40 wt. containing as impurities sodium ions) to form a clear orange solution. After 1 h, add 50 g of a colloidal solution of silica concentration of 40 wt. (Zudox type SA 40) and the mixture left overnight at room temperate yellow solution is transferred into an autoclave and maintained at 175aboutC for 10 days. Then the autoclave is cooled to room temperature and the resulting crystals are separated by filtration from the mother liquor, washed with distilled water and centrifuged. After that, the product is dried and calcined in air at 550aboutWith over 20 am

P R I m e R s 1-4. The oxidation.

Thus prepared catalyst used in the oxidation of compounds represented in table.2.

The oxidation is carried out as follows. 15 ml of the compounds are given in table. 1, 16 ml of hydrogen peroxide (30 wt.-aqueous solution), 30 ml of acetone and 1 g of the catalyst prepared according to example 1, is introduced into 130 ml th autoclave and stirred for 3 h at 100aboutC. Then, the autoclave was quickly cooled to room temperature and its composition analyzed by gas chromatography and gas chromatography/mass spectroscopy. The results of the oxidation of several compounds are given in table.2.

Conversion may depend on the effective kinetic diameter oxidizable aliphatic group.

P R I m e R 5. Conduct a series of experiments to study the influence of the amount of acetone used as a solvent in the oxidation of n-ekspeditsii examples 15 ml of n-hexane and 21 ml of an aqueous solution of hydrogen peroxide concentration of 35 wt. The reaction mixture is heated to 100aboutC for 2 h developed in the reactor pressure 7 bar (7 of 105PA).

The results are shown in table. 3.

P R I m e R 6. 310 mmol saturated alkanes listed in table.4, are oxidized by stirring in 300 ml m Parr reactor using 210 mmol of hydrogen peroxide and 400 mg silicalite titanium catalyst used in the preceding examples, in the presence of 60 ml of acetone as a solvent. The reaction is carried out for 3 h at 100aboutWhen developing a pressure of 7 bar (7 of 105PA). In all cases, the conversion of hydrogen peroxide was greater than 90% of the products obtained and their selectivity are given in table.4.

P R I m e R 7. 115 mmol of cyclohexane is oxidized with stirring in 300 ml-m reactor Parra 230 mmol of hydrogen peroxide over 14 h at 100aboutIn the presence of 45 ml of acetone and 1 g of the catalyst used in the preceding examples. Get a mixture of products containing 39 wt. cyclohexanol and 61 wt. cyclohexanone. The conversion of cyclohexane 21% hydrogen peroxide over 90%

1. The use of such silicate catalyst having a strip POV of 0.04,

to obtain a mixture of alcohols and ketones by oxidation of saturated or alkylaromatic hydrocarbons.

2. The method of obtaining a mixture of alcohols and ketones by oxidation of saturated or alkylaromatic hydrocarbons in the presence of an oxidant, heterogeneous titanium containing catalyst and a solvent under heating and under atmospheric or elevated pressure, characterized in that the oxidation is subjected to saturated hydrocarbon composition C5C10or alkyl chain length of C3C12in molecules of alkylaromatic hydrocarbons, and as a catalyst for the use of such silicate catalyst of the General formula

x TiO2(1-x) SiO2,

where x=is 0.0001 to 0.04,

having an absorption band in the infrared spectrum in the region of 950 cm-1.

3. The method according to p. 2, characterized in that the oxidizing agent is hydrogen peroxide or an aqueous solution.

4. The method according to PP. 2 and 3, characterized in that the process is carried out under pressure, ensuring the presence of organic compounds in the liquid or vapor phase.

5. The method according to PP.2 to 4, characterized in that the saturated hydrocarbons are C5is soedineniya, containing an alkyl chain length of C3C12attached to the ring structure.

7. The method according to p. 6, characterized in that the alkyl chain contains at least three carbon atoms.

8. The method according to PP.2 to 6, characterized in that the solvent used polar organic compounds dissolved in water.

9. The method according to PP. 2 to 8, characterized in that the oxidation is carried out at 50 to 150oC.

 

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