JP6604874B2 - Catalyst for the synthesis of 1,2-dichloroethane by oxychlorination of ethylene - Google Patents

Description

  The present invention relates to a catalyst used for the synthesis of 1,2-dichloroethane by oxychlorination of ethylene.

  The synthesis of 1,2-dichloroethane by oxychlorination of ethylene using a catalyst is widely used as part of a process for producing a vinyl chloride monomer, for example. As a catalyst, a carrier catalyst in which a copper compound or an alkali metal compound is supported on a carrier is used, and oxychlorination of ethylene is carried out in a fixed bed reactor. Conventionally, cylindrical or ring-shaped catalysts have been used for the synthesis of 1,2-dichloroethane. In recent years, in order to increase the efficiency of the synthesis process, the shape of the catalyst has been improved.

  Patent Document 1 proposes a supported catalyst in which three through-holes are shown, the axes of the through-holes being substantially parallel to each other and the axis of the granules, and being substantially equidistant from each other. Further, Patent Document 2 exists as a cylindrical hollow molded body having at least one through passage. When the diameter is up to 6 mm, the ratio of height to outer diameter is smaller than 1.5 and the diameter exceeds 6 mm. In that case, supported catalysts with a height to outer diameter ratio of less than 0.6 have been proposed. Patent Document 3 proposes a catalyst including a carrier having a cylindrical hollow shape including internal reinforcing blades and a diameter in a range larger than 6.5 millimeters (mm). Patent Document 4 has one hole having the same shape as the cross section of the catalyst pellet, or, optionally, two or more holes obtained by introducing a plurality of internal reinforcing blades inside the one hole. When a catalyst, two or more holes having a round shape, and four or more holes are present, a catalyst is proposed in which the distance between the centers of non-adjacent pairs of holes is not uniform.

JP-A-8-38903 JP-A-11-212465 Japanese National Patent Publication No. 11-506113 JP 2004-74152 A

  The present invention provides a catalyst capable of synthesizing 1,2-dichloroethane having a specific shape and high purity as a novel catalyst used for the synthesis of 1,2-dichloroethane by oxychlorination of ethylene.

  The present invention is a catalyst used for oxychlorination of ethylene, comprising an alumina carrier, a copper compound and an alkali metal compound supported on the alumina carrier, and the amount of the copper compound supported is the total mass of the catalyst in terms of copper element The amount of the alkali metal compound supported is 0.2 to 5% by mass with respect to the total mass of the catalyst in terms of alkali metal element, and the alumina support is in the thickness direction. It has a cylindrical shape having three cylindrical hollow inner holes having the same shape penetrating through and three substantially semi-cylindrical grooves having the same shape at the periphery, and the cylindrical shape has an outer diameter of 3.5-6. 0 mm, the height is 0.5 to 1.5 times the outer diameter, and in the cross section parallel to the bottom surface of the alumina support, the centers of the three hollow inner holes have the center of the cross section as the center of the concentric circle. Construct equilateral triangle vertices on concentric circles, and Each hollow bore is located between two grooves, and the linear distance between the two end points of each groove is the same as the diameter of each hollow bore, and the peripheral edge of the cross section The shortest distance from the part to the end of the hollow inner hole is 0.5 to 1.2 mm, and the shortest distance between the end of the hollow inner hole is greater than 0 mm and 1.2 mm or less.

  With the catalyst having a specific shape of the present invention, it is possible to suppress the production of by-products when synthesizing 1,2-dichloroethane by oxychlorination of ethylene, and to obtain 1,2-dichloroethane with high purity.

FIG. 1A is a schematic plan view of an example alumina carrier used in the present invention, and FIG. 1B is a schematic cross-sectional view thereof. FIG. 2A is a schematic plan view of a conventional ring-shaped alumina carrier, and FIG. 1B is a schematic cross-sectional view thereof. FIG. 3 is an explanatory diagram of a synthesis reaction of 1,2-dichloroethane by oxychlorination of ethylene.

  The catalyst of the present invention is a catalyst used to synthesize 1,2-dichloroethane by oxychlorination of ethylene, and includes an alumina support, a copper compound supported on the alumina support, and an alkali metal compound.

  The alumina carrier may be composed of any form of alumina (aluminum hydroxide) such as α-alumina, γ-alumina and activated alumina. Since the specific surface area is high, it is preferably composed of activated alumina or γ-alumina. The alumina carrier can be obtained by molding aluminum hydroxide powder with a tableting machine and firing at 500 ° C. or higher. During molding, the aluminum hydroxide powder may contain additives such as a lubricant and a pore-forming agent. For example, an additive such as a lubricant may be added in an amount of 8 parts by mass or less with respect to 100 parts by mass of aluminum hydroxide.

  Hereinafter, the shape and size of the alumina support will be described with reference to the drawings. FIG. 1A is a schematic plan view of an example alumina carrier used in the present invention, and FIG. 1B is a schematic cross-sectional view thereof. The alumina carrier used in the present invention is not limited to the one shown in FIG.

  The alumina carrier 1 has a cylindrical shape having three hollow cylindrical holes 2 with the same shape penetrating in the thickness direction and three substantially semi-cylindrical grooves 3 with the same shape at the peripheral edge. The outer diameter D1 is 3.5 to 6.0 mm, and the height H is 0.5 to 1.5 times the outer diameter D1. When the outer diameter D1 is 3.5 mm or more, the resistance of the catalyst to the fluid is small and the molding cost can be suppressed. When the outer diameter D1 is 6 mm or less, catalytic activity and thermal conductivity are improved. When the height H is 0.5 to 1.5 times the outer diameter D1, the resistance of the catalyst to the fluid decreases. The outer diameter D1 is preferably 4 to 5.5 mm, and more preferably 4.5 to 5.5 mm. The height H is preferably 0.7 to 1.3 times the outer diameter D1, and more preferably 0.6 to 1.2 times.

  In the cross section (transverse cross section) parallel to the bottom surface of the alumina carrier 1, the centers of the three hollow inner holes 2 constitute apexes of equilateral triangles concentrically with the center of the cross section, and each hollow inner hole 2 has two It arrange | positions so that it may be located between a groove | channel. The linear distance Dg between the two end points of each groove 3 is the same as the diameter Dh of each hollow inner hole 2. When the linear distance Dg between the two end points of the groove 3 is the same as the diameter Dh of the hollow inner hole 2, the strength is stabilized. The diameter Dh of the hollow inner hole 2 may be 1 to 2 mm or 1.2 to 2 mm.

  In a cross section (transverse cross section) parallel to the bottom surface of the alumina carrier 1, the shortest distance W1 from the peripheral edge of the cross section to the end of the hollow bore is 0.5 to 1.2 mm, and the shortest distance between the ends of the hollow bore W2 is greater than 0 mm and not greater than 1.2 mm. By-products are reduced when the shortest distance W1 from the peripheral edge of the cross section to the end of the hollow bore and the shortest distance W2 between the ends of the hollow bore are within the above ranges. Preferably, W1 is 0.5 to 1 mm and W2 is 0.1 to 1 mm.

  In the present invention, the alumina carrier can be made to have a predetermined shape and size by compression molding an alumina powder or, if necessary, a mixture obtained by adding an additive such as a lubricant to the alumina powder. The compression molding can be performed using a mold having a predetermined shape and size and a tablet molding machine such as a tableting machine.

From the viewpoint of suppressing by-products, the alumina carrier preferably has a pore volume measured by a mercury intrusion method in accordance with JIS R 1655 in the range of 0.25 to 0.60 cm ³ / g, more preferably. It is in the range of 0.30 to 0.50 cm ³ / g.

The alumina support preferably has a specific surface area of 150 to 300 m ² / g, more preferably 180 to 250 m ² / g, as measured by the BET method in accordance with JIS Z 8830, from the viewpoint of improving catalytic activity. preferable.

  On the alumina support, a copper compound and an alkali metal compound are supported as a catalyst metal compound. The copper compound is supported in an amount of 1 to 12% by mass in terms of copper element, preferably 2 to 10% by mass, based on the total mass of the alumina support and the catalyst metal compound, that is, the total mass of the catalyst. 3-9 mass% is more preferably supported. The alkali metal compound is supported in an amount of 0.2 to 5% by mass in terms of alkali metal element based on the total mass of the alumina support and the catalyst metal, that is, the total mass of the catalyst, and 0.3 to 4.5% by mass. It is preferably supported and more preferably 0.5 to 4% by mass. When the supported amount of the copper compound and alkali metal compound supported on the alumina carrier is in the above-described range, the catalytic activity is improved and the production of by-products is suppressed.

  As said copper compound, bivalent copper compounds, such as copper nitrate, copper sulfate, copper carbonate, copper halide, can be used. Examples of copper halides include copper chloride and copper bromide. Among these, copper halide is preferably used, and copper chloride is more preferably used. These copper compounds may be used alone or in combination of two or more.

  As the alkali metal compound, all ionic alkali metal compounds can be used. Examples include alkali metal chlorides, sulfates, carbonates and nitrates. In the alkali metal compound, the alkali metal may be any of lithium, sodium, potassium, rubidium, and cesium. One or more selected from the group consisting of sodium, potassium, rubidium and cesium halides are preferred, sodium chloride and / or potassium chloride is more preferred, and potassium chloride is even more preferred.

  The method for supporting the copper compound and alkali metal compound on the alumina support is not particularly limited. From the viewpoint of simple operation and high loading efficiency, an immersion method in which an alumina carrier is impregnated with an aqueous solution containing a copper compound and an alkali metal compound can be used. After impregnating the alumina carrier with an aqueous solution containing a copper compound and an alkali metal compound, the alumina carrier is dried, whereby the copper compound and the alkali metal compound are supported on the alumina carrier.

From the viewpoint of suppressing by-products, the catalyst of the present invention preferably has a pore volume measured by a mercury intrusion method in accordance with JIS R 1655 in the range of 0.25 to 0.60 cm ³ / g, more preferably. Is in the range of 0.30 to 0.50 cm ³ / g.

  The catalyst of the present invention can be used in a general fixed bed oxychlorination reactor by filling a reactor instead of a conventional catalyst. By using the catalyst of the present invention, it is possible to suppress the production of by-products and produce 1,2-dichloroethane with high purity.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to the following Example.

(Example 1)
<Production of catalyst>
A mixture obtained by adding magnesium stearate as a lubricant to aluminum hydroxide powder is molded with a tableting machine and then calcined at 550 ° C. for 2 hours, and an alumina carrier having the shape and size shown in FIG. 1 and Table 2 Got. The pore volume of the obtained alumina carrier was measured by a mercury intrusion method according to JIS R 1655, and the results are shown in Table 2 below. Further, the specific surface area of the obtained carrier was measured by the BET method in accordance with JIS Z 8830, and the results are shown in Table 2 below. Next, the obtained alumina carrier was immersed in an aqueous solution containing CuCl ₂ and KCl and then dried, whereby the alumina carrier was supported with CuCl ₂ and KCl, and CuCl ₂ was 16.5% by mass and KCl was 1.5%. A catalyst containing mass% was obtained. The pore volume of the obtained catalyst was measured by a mercury intrusion method according to JIS R 1655, and the results are shown in Table 2 below.
<Synthesis of 1,2-dichloroethane>
The reactor has a nickel tube with an inner diameter of 20.86 mm and a length of 1200 mm, and a jacket welded to the outer periphery of the nickel tube with a gas tube having a diameter of 5.08 cm (2 inches). The inside of the jacket is a heat medium (barrel silicon). A bowl-shaped one configured to circulate fluid ST) in liquid form was used. At the center of the nickel tube, a temperature measuring nickel tube having an outer diameter of 4 mm was inserted and installed. A pressure gauge was attached to the reactor inlet so that the pressure in the reactor could be measured. 263 mL of the catalyst obtained above was charged in an intermediate portion having a distance of 205 to 1005 mm from the upper end of the reactor, and graphite and 26 mL and 63 mL of graphite were charged in the upper and lower portions of the reactor, respectively.
As shown in FIG. 3, hydrogen chloride, ethylene, air and nitrogen were mixed and supplied to the reactor as reaction raw material gases. The flow rate of hydrogen chloride was 38.2 NL / hr, the flow rate of ethylene was 25.4 NL / hr, the flow rate of air was 58.0 NL / hr, and the flow rate of nitrogen was 453.3 NL / hr. The reactor inlet pressure was maintained at 3 kg / cm ² . The test was conducted while adjusting the temperature of the heat medium in the jacket so that the reaction rate of oxygen in the supplied air was about 80%. The temperature in the reactor was measured at 36 locations with a temperature measuring nickel tube, and the highest temperature was defined as the hot spot temperature. When the heat medium temperature was 200 ° C., the reaction was performed under two conditions when the heat medium temperature was 210 ° C.

(Comparative Example 1)
A mixture obtained by adding magnesium stearate as a lubricant to aluminum hydroxide powder is molded with a tableting machine and then calcined at 550 ° C. for 2 hours, and an alumina carrier having the shape and size shown in FIG. 2 and Table 2 Got. A catalyst was prepared in the same manner as in Example 1 except that the obtained alumina support was used, and a synthesis reaction of 1,2-dichloroethane was performed.

In Example 1 and Comparative Example 1, the reaction product exiting from the reactor was analyzed. The reaction product contains a reaction gas and a reaction solution, and the reaction solution is divided into an aqueous layer and an organic layer, and these were analyzed by an apparatus shown in Table 1 below. After analysis, the purity (mass%) of 1,2-dichloroethane (hereinafter also referred to as “EDC”) in the reaction product and the total concentration (mass%) of CO and CO ₂ were calculated. It is shown in Table 2. In Table 1 below, GC means gas gromatograph.

As can be seen from the results in Table 2, the use of the catalyst of Example 1 in which the carrier has a specific structure is more effective than the case of using the catalyst of Comparative Example 1 using a conventional ring-like carrier. The purity of 2-dichloroethane was high and the total concentration of CO and CO ₂ was low.

1 Alumina carrier 2 Hollow inner hole 3 Groove

Claims (1)

A catalyst used for oxychlorination of ethylene, comprising an alumina carrier, a copper compound and an alkali metal compound supported on the alumina carrier, and the amount of the copper compound supported is 1 in terms of copper element with respect to the total mass of the catalyst. The amount of the alkali metal compound supported is 0.2 to 5% by mass with respect to the total mass of the catalyst in terms of alkali metal element,
The alumina support has a cylindrical shape having three hollow cylindrical holes having the same shape and penetrating in the thickness direction, and three substantially semi-cylindrical grooves having the same shape at the peripheral edge portion. The outer diameter is 3.5 to 6.0 mm, the height is 0.5 to 1.5 times the outer diameter,
In the cross section parallel to the bottom surface of the alumina support, the centers of the three hollow inner holes constitute a vertex of an equilateral triangle on a concentric circle having the center of the cross section as the center of the concentric circle, and each hollow inner hole has two grooves. The linear distance between the two end points of each groove is the same as the diameter of each hollow bore, and from the peripheral edge of the cross section to the end of the hollow bore The shortest distance is 0.5 to 1.2 mm, and the shortest distance between the end portions of the hollow inner holes is greater than 0 mm and 1.2 mm or less.

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