The preparation method of catalyst for ethylene oxide

 

(57) Abstract:

The invention relates to the chemical industry, and in particular to methods of preparation of catalysts for the process of ethylene oxide gas-phase oxidation of ethylene with oxygen. According to this invention the catalyst is obtained by impregnation of the carrier with an aqueous solution of amine complex salt of silver, containing the promoter is a compound of an alkali metal selected from the group comprising potassium, rubidium, cesium, compound containing fluoride anion, which is used as the fluoride of the alkali metal is potassium, rubidium or cesium, and the connection of copromotor - salt of metal selected from the group comprising magnesium, calcium, barium, zinc, cadmium, aluminum, lanthanum, then the impregnated carrier is treated with a fluoride of an alkali metal in the presence of surfactant, followed by drying the catalyst mass. Obtained according to the invention, the catalyst has high activity and selectivity. table 2.

The invention relates to the chemical industry, and in particular to methods of preparation of the catalyst for the process of ethylene oxide (MA) gas-phase oxidation of ethylene with oxygen.

inert carrier amine complex salts of silver with the addition of alkali metals [U.S. patent 4415476, 1983] .

Also known preparation method of the catalyst for oxidation of ethylene to ethylene oxide, comprising an inert carrier impregnated with a solution of silver compounds, containing as alkaline promoter sodium and cesium in cationic form and at least one halogen element selected from chlorine, bromine and fluorine, as an anionic component [patent UK 1413251, 1975] .

The closest to the technical nature of the proposed method is a preparation method of catalyst for ethylene oxide, comprising a carrier impregnated, pre-treated with fluoride of an alkali metal and subsequent firing of the media when 1400-1600oWith, an aqueous solution of amine complex salt of silver, providing a deposition on the carrier 1-25 wt. % silver-containing promoter is a compound of an alkali metal selected from the group comprising potassium, rubidium, cesium, and a compound containing fluoride anion, followed by drying the catalyst mass [patent RU 2034648 C1, 10.05.1995] . According to well-known solution in the aqueous solution of amine complex salt of silver, alkali promoter is injected in the form of salts or hydroxides, as a compound containing fluoride anion, tx2">

The disadvantages of the known solutions should include sufficient activity and selectivity of the catalyst, obtained in a known manner, and the complexity of the technology, providing for high-temperature calcination of the carrier.

Object of the present invention is to provide a preparation method of catalyst for ethylene oxide with high performance and simplifying technology.

To solve the problem proposed by the present preparation method of catalyst for ethylene oxide by impregnation of the carrier with an aqueous solution of amine complex salt of silver, containing the promoter is a compound of an alkali metal selected from the group comprising potassium, rubidium, cesium, and the connection of copromotor - salt of metal selected from the group comprising magnesium, calcium, barium, zinc, cadmium, aluminum, lanthanum, then the impregnated carrier is treated with a fluoride of an alkali metal in the presence of surfactant, followed by drying the catalyst mass.

Add in the impregnating solution of the compound of copromotor and use it as a compound containing fluoride anion, fluoride, alkali meta is s active silver surface. In addition, the connection of copromotor together with the fluorine has a modifying effect on the silver catalyst and increases its selectivity.

The procedure of stages of preparation of the catalyst according to the invention, providing for the application of a fluoride of an alkali metal in the presence of surfactants on impregnated with a solution of silver salts media, contributes to the formation of alkali promoter, strongly associated with the surface of the carrier, this eliminates stage high-temperature calcination of the carrier.

As media use alpha-alumina, aluminosilicates, silicon carbide in the form of balls or rings size 5-8 mm, a specific surface area of up to 1 m2/g and a porosity of 30-60%. As silver salts and metals, used as copromotor, you can use any water-soluble salts of organic and inorganic acids (for example, lactates, acetates, nitrates). As surface-active substances, use of surfactants, biodegradable residue when heated.

The use of the invention will increase the catalyst activity at 5-17% and the selectivity of the catalyst at 2-2,3% compared to the prototype.

Get 1200 ml of impregnating solution containing 515 g of silver (25 wt. %), which is impregnated with 4 l of media.

The impregnated carrier is dried with stirring at a temperature of 50oWith the stream of inert gas for 3 hours to Raise the temperature to 70oWith and maintain the sample at this temperature for 24 hours the sample Obtained is washed with distilled water until the colour disappears wash liquid and to the disappearance in the wash liquid ion NO3. The sample was then dried at a temperature of 120oC for 4 h and after drying impregnated with 2500 ml of an aqueous solution containing 0.1% cesium fluoride (component D) and 0.1% polyoxy within 1 hour Drain the excess liquid and dried catalyst mass at a temperature of 140oC for 4 h in air flow.

Examples 2-12. The catalysts prepared according to example 1, the conditions of preparation, the 2.

Examples 13, 14 (comparative). The catalyst prepared according to example 1. In example 13, the fluoride of the alkali metal is not added in example 14 as a compound containing fluoride anion, using ammonium fluoride.

Samples of the catalysts tested in the oxidation of ethylene. Test conditions: the reactor of stainless steel with an inner diameter of 8 mm, the Composition of the source gas, about. %: ethylene 20, 6 oxygen, nitrogen else. The pressure of the reaction mixture of 20 ATM. The volume flow of the gas mixture 600-1including as a gas promoter add dichloride in an amount of 0.1 ppm. Temperature tests 210-230oC. the test Results are presented in table 2.

The preparation method of catalyst for ethylene oxide, including handling media fluoride of an alkali metal, the carrier impregnated with the aqueous solution of amine complex salt of silver, containing the promoter is a compound of an alkali metal selected from the group comprising potassium, rubidium, cesium, and a compound containing fluoride anion, drying the catalyst mass, characterized in that the first by impregnation of the support with a solution of silver salts containing as a compound containing fluoride anion, fluoride saloon uppy, including magnesium, calcium, barium, zinc, cadmium, aluminum, lanthanum, then the impregnated carrier is treated with a fluoride of an alkali metal in the presence of surfactant, followed by drying the catalyst mass.

 

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