RU2352393C1 - Catalyst, method of its preparation and process of methanol hydrochlorating - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: catalyst contains zinc chloride and carrier - porous granulated carbon-carbonic composition material based on pyrocarbon and nanodispersed carbon with specific surface by "БЭТ" 350-650 m²/g and total pore volume by water 0.55-0.85 cm³/g. Described is method of preparation of catalyst described above, which is prepared by impregnating carrier with water or hydrochloric acid solution of zinc chloride in two stages: zinc chloride sorption by carrier from water solution at temperature 15-25°C and evaporation of remaining part of solution at temperature 80-100°C. Also described is process on obtaining methylchloride by catalytic hydrochlorating of methanol, which is carried out in continuous reactor at temperature 140-200°C and contact time 0.6-1.11 s in presence of described above catalyst.

EFFECT: complete methanol conversion and complete selectivity to methylchloride.

7 cl, 6 ex, 4 dwg

Description

The invention relates to the field of organic synthesis, namely to the production of methyl chloride by catalytic hydrochlorination of methanol.

Known liquid-phase and vapor-phase catalytic methods for producing methyl chloride by the interaction of methanol with hydrogen chloride.

A known method of producing methyl chloride in the liquid phase, which includes the treatment of methanol with hydrogen chloride at a molar ratio of hydrogen chloride: methanol (1.8-2.2): 1 in the liquid phase at elevated temperature. Hydrogen chloride is supplied in the form of an aqueous solution with a concentration of 35-45 wt.% (RF 2152920, С07С 19/03, 2000.07.20).

A known method of producing methyl chloride, where in order to increase the yield of chloromethyl and suppress the reaction of the formation of a by-product - dimethyl ether, the synthesis is carried out in two stages in a large (2 or more moles) excess of hydrogen chloride in the presence of an amine type catalyst (for example, aniline). At the first stage, a saturated solution of hydrogen chloride in a water-methanol mixture is obtained at room temperature, and then, heating the resulting solution to 106-110 ° C, gaseous methyl chloride is isolated (RF 2070188, С07С 19/03, 1996.12.10).

A known liquid-phase method for producing methyl chloride, where a solution of zinc chloride is used as a catalyst (US 4922043, C07C 17/16, 1990.05.01).

The disadvantages of these methods are the need for separation of methyl chloride from the liquid phase and the formation of dimethyl ether as a by-product.

A known method of vapor-phase hydrochlorination of alcohols (including methanol) to produce alkyl chlorides using supported zinc chloride as a catalyst (EP 1421992, B01J 21/18; B01J 27/138, 05.26.2004). In this case, the catalyst is obtained by mixing a solid support with zinc oxide, followed by treating the resulting material with hydrogen chloride or a mixture of hydrogen chloride with water vapor, in which zinc oxide is converted into zinc chloride.

The disadvantage of this method is a complex method for producing a catalyst.

A hydrochlorination catalyst is known which includes η-alumina doped with cesium chloride. Also claimed is a method of hydrochlorinating methanol in the vapor phase using the above catalyst.

The disadvantages of the catalyst and the method of producing methyl chloride is the formation of dimethyl ether and carbonization of the catalyst.

Closest to the proposed invention is a method of producing methyl chloride by catalytic vapor-phase interaction of methanol and hydrogen chloride in a shelf reactor containing two catalyst layers at the inlet and outlet temperatures of each catalyst layer, respectively, 140-160 and 330-350 ° C, characterized in that with the aim To increase the productivity of the process, methanol is fed simultaneously into two catalyst layers in an amount of 50-95 wt.% in the first catalyst layer and 5-50 wt.% in the second catalyst layer. The process is conducted in the presence of a catalyst, which is zinc chloride on a support — alumina or activated carbon, or active alumina, or cadmium chloride deposited on alumina (RF 1039150, С07С 17/06, 2000.06.27).

The disadvantages of the catalyst and the method of producing methyl chloride are the formation of dimethyl ether, carbonization of the catalyst and low mechanical strength of the catalyst containing activated carbon as a carrier.

The objective of the invention is to develop a catalyst for the production of methyl chloride by catalytic paraphase hydrochlorination of methanol with high mechanical strength and capable of providing high catalytic activity and selectivity for methyl chloride at low temperatures.

The problem is solved by the composition of the catalyst, which contains zinc chloride as an active component, deposited on a porous granular carbon-carbon composite material based on pyrocarbon and nanosized carbon with a BET specific surface area of 350-650 m ² / g and a total water pore volume of 0.55 -0.85 cm ³ / g.

The catalyst contains 15-25 wt.% Zinc chloride, the rest is a porous granular carbon-carbon composite material based on pyrocarbon and nanosized carbon

The problem is also solved by the method of preparation of the catalyst for producing methyl chloride by catalytic paraphase hydrochlorination of methanol methanol. The catalyst is prepared by impregnating a carbon support — a porous granular carbon-carbon composite material based on pyrocarbon and nanosized carbon with a BET specific surface area of 350-650 m ² / g and a total pore volume in water of 0.55-0.85 cm ³ / g aqueous or hydrochloric acid solution of zinc chloride in two stages: sorption of zinc chloride by a carbon carrier from an aqueous solution at a temperature of 15-25 ° C and evaporation of the remainder of the solution at a temperature of 80-100 ° C, while receiving a catalyst containing 15-25 wt.% zinc chloride, ost The other is the carrier.

The concentration of zinc chloride in the impregnating solution is 50-150 g / L.

The concentration of hydrochloric acid in the impregnating solution is 0.5-1.5 M.

The problem is also solved by the method of producing methyl chloride by catalytic hydrochlorination of methanol, which is carried out in a flow reactor at a temperature of 140-200 ° C and a contact time of 0.6-1.11 s in the presence of a catalyst that contains zinc chloride in the amount of 15-25 as an active component wt.% deposited on a porous granular carbon-carbon composite material based on pyrocarbon and nanodispersed carbon with a BET specific surface area of 350-650 m ² / g and a total water pore volume of 0.55-0.85 cm ³ / g.

The characteristics of the media used are shown in table 1.

Table 1 Characteristics of Carbon Carriers No. p / p The name of indicators Units rev. Media 1 Carrier-2 one BET specific surface area m ² / g 400 568 2 The total pore volume of the carrier in water (moisture capacity) cm ³ / g 0.80 0.79 3 The bulk density of the carrier g / cm ³ 0.5 0.55

The invention is illustrated by the following examples.

Example 1

5 g of zinc chloride is dissolved in 50 ml of distilled water, the resulting solution is poured into 20 g of carrier-1. The carrier is impregnated in two stages: at the first stage, zinc chloride is sorbed by the carrier from an aqueous solution at a temperature of 15-25 ° C until an equilibrium degree of sorption of 60-65% is reached, and at the second stage, an excess of the impregnation solution is evaporated with stirring at a temperature of 80-100 ° C until air-dry. The dried sample is tested in the reaction of methanol hydrochlorination in a flow reactor in the temperature range from 60 to 200 ° C. In order to avoid temperature gradients and condensation of products from the gas phase, the reaction mixture is diluted with helium. Analysis of the reaction products is carried out by gas chromatography on a Tsvet-100 chromatograph with a thermal conductivity detector using a packed column: 5% SE-30 phase deposited on N-AW chromaton, fr. 0.125-0.160 mm.

The test results of the catalytic characteristics are shown in table 2.

table 2

и селективность по метилхлориду

в реакции гидрохлорирования метанола на 20% ZnCl₂/носитель-1 при соотношении HCl/СН₃ОН=1,2 и времени контакта 0,6 сThe dependence of the degree of conversion of methanol

and methyl chloride selectivity

in the reaction of methanol hydrochlorination with 20% ZnCl ₂ / carrier-1 with a ratio of HCl / CH ₃ OH = 1.2 and a contact time of 0.6 s t, ° С 60 one hundred 140 180 200

% 76.6 87.5 97.4 99.6 97.3

% 42.7 90.3 95.1 96.2 95.3

Example 2

The catalyst is prepared analogously to example 1, the difference is that the carrier is impregnated with hydrochloric acid solution (1M HCl) of zinc chloride.

Example 3

The catalyst is prepared analogously to example 2, the difference is that media-2 is used as a carrier.

The results of the catalytic activity test for examples 2 and 3 are shown in Fig.1-4. Contact time 1.11 s, CH ₃ OH: HCl: He = 1: 1.6: 8.4.

It is seen that the degree of conversion of methanol for the sample prepared in example 2 increases with increasing temperature from 48 to 88% (Figure 1), while increasing the selectivity for methyl chloride from 72 to 98 mol% (Figure 2). For the sample prepared in example 3, the degree of conversion increases from 65 to 100% (Figure 3) with an increase in selectivity from 85 to 100 mol% (Figure 4).

Example 4

The catalyst prepared in Example 3 was tested at 160 ° C. for 300 hours. The catalyst retained its catalytic activity and selectivity completely. The constancy of catalytic activity over time indicates a sharp decrease in coke formation.

Example 5

The catalyst is prepared analogously to example 2. The difference is that a portion of zinc chloride is taken in the amount necessary to obtain a catalyst with a composition of 15 wt.% ZnCl ₂ / carrier-1. Catalytic tests carried out under similar conditions as examples 2-3 show that at 160 ° C the degree of conversion of methanol is 99% with a selectivity for methyl chloride of 98 mol.%.

Example 6

Comparative prototype (RF 1039150, С07С 17/06, 2000.06.27). Zinc chloride is deposited on activated carbon grade AP-3. Contact time 6.2 s.

Table 3 shows the temperatures of achieving 99% conversion and selectivity for the catalysts in examples 1-6.

Table 3 Example No. The temperature to achieve the conversion of 99%, ° C Methyl chloride selectivity,% one* 175 96 2 * 220 98 3 * 180 one hundred four* 180 one hundred 5* 160 98 6 (comparative) *** 330 99 • - contact time 0.6 s
• ** - contact time 1.1 s
• *** - contact time 6.2 s

The test results of the catalysts indicate the achievement of the objectives of the invention. New catalysts can reduce the process temperature from 330 to 160-180 ° C and increase the productivity of the process by reducing contact time. In this case, 100% methanol conversion and 100% methyl chloride selectivity are achieved.

Claims (7)

1. A catalyst for producing methyl chloride by catalytic vapor-phase hydrochlorination of methanol containing zinc chloride and a carbon carrier, characterized in that it contains a porous granular carbon-carbon composite material based on pyrocarbon and nanodispersed carbon with a BET specific surface area of 350-650 m ² / g and the total pore volume in water of 0.55-0.85 cm ³ / g 2. The catalyst according to claim 1, characterized in that it contains 15-25 wt.% Zinc chloride, the rest is a porous granular carbon-carbon composite material based on pyrocarbon and nanosized carbon. 3. A method of preparing a catalyst for producing methyl chloride by catalytic vapor-phase hydrochlorination of methanol by impregnating a carbon support with an aqueous or hydrochloric acid solution of zinc chloride, characterized in that the support is a porous granular carbon-carbon composite material based on pyrocarbon and nanosized carbon with a specific surface area of BET 350- 650 m ² / g and a total pore volume in water of 0.55-0.85 cm ³ / g, and the impregnation is carried out in two stages, in the first stage, sorption of qi chloride a carbon carrier from an aqueous solution at a temperature of 15-25 ° C, and in the second stage, the remaining part of the solution is evaporated at a temperature of 80-100 ° C. 4. The method of preparation according to claim 3, characterized in that the concentration of zinc chloride in the impregnating solution is 50-150 g / L. 5. The method of preparation according to claim 3, characterized in that the concentration of hydrochloric acid in the impregnating solution is 0.5-1.5 M. 6. The method of producing methyl chloride by catalytic vapor-phase hydrochlorination of methanol, characterized in that the catalyst used is the catalyst according to any one of claims 1 and 2, or prepared according to any one of claims 3 and 5. 7. The production method according to claim 6, characterized in that the process is carried out in a flow reactor at a temperature of 140-200 ° C and a contact time of 0.6-1.11 s.

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