A preparation method of 2,3-dichloropyridine

Abstract

The present invention belongs to the field of chemical synthesis technology, and in particular to a preparation method of 2,3-dichloropyridine. The preparation method adopts 2,3,6-trichloropyridine as raw material, HCOONa and ammonia as acid binding agent, methanol as solvent, and in the presence of a supported catalyst, hydrogenation reaction obtains 2,3-dichloropyridine. The reaction conditions are: reaction temperature: room temperature ~ 100 ° C; reaction pressure: 0.1 ~ 1Mpa; reaction time: 2 ~ 10h; the carrier of the supported catalyst is coconut shell columnar carbon: the auxiliary agent is Ni and Ca, and the active component is Pt and Ir, in terms of coconut shell columnar carbon mass: the loading amount of Ni is 1 ~ 3wt%; the loading amount of Ca is 0.5 ~ 2.5wt%; the loading amount of Pt is 0.5 ~ 1.5wt%; the loading amount of Ir is 0.1 ~ 0.7wt%. By adopting the preparation method of the present application, there is an excellent product yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical synthesis and more specifically relates to a method for preparing 2,3-dichloropyridine. Background Art

[0002] 2,3-Dichloropyridine is an important intermediate for medicine and pesticides, especially in the field of pesticides. It is an important intermediate for the synthesis of the new insecticide chlorantraniliprole and has broad application prospects. The main industrial synthesis method of 2,3-dichloropyridine is to use 2-chloro-3-aminopyridine as the starting material, and obtain it through two steps of diazotization and Sandmeyer chlorination. The main advantage of this method is that the intermediates do not need to be purified, all processes can be completed in the same reaction pot, and hydrochloric acid is used as the solvent, which is cheap; its disadvantage is that the raw material 2-chloro-3-aminopyridine is relatively expensive, and the diazotization and chlorination steps will produce a large amount of waste liquid, which seriously pollutes the environment and restricts its large-scale industrial application.

[0003] The preparation of 2,3-dichloropyridine by catalytic hydrogenation using 2,3,6-trichloropyridine as raw material has the advantages of cheap raw material price, simple process and clean production. It is a synthetic route with great application prospects.

[0004] CN107266357B discloses a method for synthesizing 2,3-dichloropyridine (III), the steps of which are: 1) using pyridine (I) as the main starting material, water or water vapor as the reaction medium, in the presence of a chlorination inducing agent, pyridine and chlorine react to completion to obtain pyridine chloride (II) as the next step reaction raw material; 2) using the pyridine chloride (II) obtained in the first step as the reaction raw material, water or water vapor as the reaction medium, in the presence of an acid binding agent and a catalyst, pyridine chloride (II) is contacted with hydrogen, and a catalytic hydrogenation reduction reaction is performed to obtain 2,3-dichloropyridine (III) with a purity of more than 99%, wherein the catalyst is a nano IrO2-ZnO-MnO2 composite catalyst. The reaction equation is: wherein n=2-5. The invention has the advantages of high reaction conversion rate and selectivity, stable product quality, simple production operation, low cost, etc., and overcomes the shortcomings of the existing synthesis method that the quality of 2,3-dichloropyridine (III) is unstable and must be distilled multiple times to make the quality of 2,3-dichloropyridine (III) meet the standard.

[0005] CN108380208B discloses a Pd-Mg / C catalyst for preparing 2,3-dichloropyridine by catalytic hydrogenation of 2,3,6-trichloropyridine and a preparation method thereof. The catalyst is prepared by mixing Na2PdCl4 and MgCl2 with an activated carbon carrier treated with hydrogen peroxide and hydrochloric acid in the presence of sodium tartrate, and then reducing the catalyst with H2 after drying to obtain the Pd-Mg / C catalyst. The catalyst preparation process of the present invention realizes that the nano-metal is highly dispersed on the carrier, and the acid-base state of the catalyst surface is adjusted by the auxiliary agent Mg, thereby improving the selectivity of 2,3-dichloropyridine, and enhancing the interaction between the noble metal palladium and the carrier. The catalyst has good stability, improves the reusability of the catalyst, and is conducive to reducing production costs.

[0006] CN110003099B discloses a method for preparing 2,3-dichloropyridine and the obtained 2,3-dichloropyridine, wherein 2,3,6-trichloropyridine is used as a raw material, hydrogen is used as a hydrogen source, a noble metal organic compound is used as a main catalyst, and other organic phosphine compounds are added as co-catalysts under certain pressure and temperature conditions to carry out catalytic hydrogenation reaction and post-treatment to obtain 2,3-dichloropyridine. By using the organic phosphine compound, on the basis of greatly reducing the amount of the noble metal organic compound and the reaction time, a very good raw material 2,3,6-trichloropyridine conversion rate and 2,3-dichloropyridine selectivity can still be obtained, the conversion rate of 2,3,6-trichloropyridine is as high as 99%, the selectivity of 2,3-dichloropyridine is more than 94%, and the post-treatment process is simpler and suitable for industrial production.

[0007] In summary, although the existing preparation process is relatively mature, the activity of the catalyst used is not high and the yield is low. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defects and deficiencies in the prior art and provide a method for preparing 2,3-dichloropyridine. The preparation method uses 2,3,6-trichloropyridine as a raw material, HCOONa and ammonia water as an acid binding agent, methanol as a solvent, and hydrogenates in the presence of a supported catalyst to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: room temperature to 100°C; reaction pressure: 0.1 to 1Mpa; reaction time: 2 to 10h; the carrier of the supported catalyst is coconut shell columnar carbon: the auxiliary agent is Ni and Ca, the active component is Pt and Ir, and the weight of the coconut shell columnar carbon is: the loading amount of Ni is 1 to 3wt%; the loading amount of Ca is 0.5 to 2.5wt%; the loading amount of Pt is 0.5 to 1.5wt%; the loading amount of Ir is 0.1 to 0.7wt%. The preparation method of the present application has an excellent product yield.

[0009] The purpose of the present invention is to provide a method for preparing 2,3-dichloropyridine.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, HCOONa and ammonia water as an acid-binding agent, methanol as a solvent, and hydrogenation reaction in the presence of a supported catalyst to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: room temperature to 100°C; reaction pressure: 0.1 to 1 MPa; reaction time: 2 to 10 hours;

[0012] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 1-3wt%; the loading amount of Ca is 0.5-2.5wt%; the loading amount of Pt is 0.5-1.5wt%; and the loading amount of Ir is 0.1-0.7wt%.

[0013] Preferably, the molar ratio of HCOONa to ammonia water is 1:2-4; the molar ratio of the acid binding agent to the raw material is 1-2:1; the mass ratio of the solvent to the raw material is 1-10:1; and the mass ratio of the supported catalyst to the raw material is 0.01-0.5%.

[0014] Preferably, the preparation method of the supported catalyst is as follows:

[0015] (1) putting coconut shell columnar carbon into an activation furnace for activation, placing the activated coconut shell columnar carbon into hydrogen peroxide for reaction, filtering, washing to neutrality, and drying to obtain modified coconut shell columnar carbon;

[0016] (2) then ultrasonically dispersing the modified coconut shell columnar carbon, the nickel source and the calcium source into deionized water, standing, drying and calcining to obtain product A;

[0017] (3) The obtained product A, platinum source and iridium source are ultrasonically dispersed in deionized water, allowed to stand, dried, calcined, reduced, and then reduced at 200-300° C. for 2-4 hours in a hydrogen atmosphere to obtain a supported catalyst.

[0018] Preferably, in step (1), the activation conditions are: the activation gas is water vapor, the activation temperature is 200-300° C., and the activation time is 8-16 hours.

[0019] Preferably, in step (1), the mass concentration of the hydrogen peroxide is 10-20wt%; the reaction is carried out at 40-60°C for 2-4h; the mass ratio of the coconut shell columnar charcoal to the hydrogen peroxide is 1:2-3; and the drying is carried out at 80-120°C for 12-18h.

[0020] Preferably, in step (2), the standing time is 10 to 14 hours; the drying is performed at 100 to 140° C. for 12 to 24 hours; and the calcining is performed at 450 to 550° C. for 3 to 7 hours.

[0021] Preferably, in step (3), the standing time is 10 to 14 hours; the drying is performed at 100 to 140° C. for 12 to 24 hours; and the calcination is performed at 450 to 550° C. for 3 to 7 hours.

[0022] Preferably, in step (3), the reduction conditions are: reduction at 200-300°C for 2-4 hours under a hydrogen atmosphere.

[0023] Preferably, the nickel source is at least one of nickel nitrate, nickel chloride and nickel acetate; the calcium source is at least one of calcium nitrate, calcium chloride and calcium acetate; the platinum source is chloroplatinic acid; and the iridium source is chloroiridic acid.

[0024] Preferably, based on the mass of coconut shell columnar carbon: the loading amount of Ni is 1-3wt%; the loading amount of Ca is 0.5-2.5wt%; the loading amount of Pt is 0.5-1.5wt%; and the loading amount of Ir is 0.1-0.7wt%.

[0025] The present invention has the following beneficial effects:

[0026] (1) The present invention can significantly improve the selectivity of the target product and the yield by using a composite acid binding agent;

[0027] (2) The present invention uses coconut shell columnar carbon to be treated with water vapor and hydrogen peroxide, which can significantly improve the coconut shell columnar carbon, significantly improve the dispersibility of the active component, and further improve the yield of the target product;

[0028] (3) The activity of the active component can be significantly improved and the yield of the target product can be increased by adding auxiliary agents and step-by-step impregnation;

[0029] (4) The preparation process of the present invention is simple, the raw material source is abundant, and it has excellent application prospects. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0031] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0032] Example 1

[0033] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0034] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0035] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0036] The preparation method of the supported catalyst is as follows:

[0037] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0038] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0039] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0040] Example 2

[0041] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 50°C; reaction pressure: 0.1Mpa; reaction time: 10h.

[0042] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 3wt%; the loading amount of Ca is 0.5wt%; the loading amount of Pt is 1.5wt%; and the loading amount of Ir is 0.1wt%.

[0043] The molar ratio of HCOONa to ammonia water is 1:4; the molar ratio of the acid binding agent to the raw material is 2:1; the mass ratio of the solvent to the raw material is 10:1; and the mass ratio of the supported catalyst to the raw material is 0.5%.

[0044] The preparation method of the supported catalyst is as follows:

[0045] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 300° C., the activation time was 8 h, the activated coconut shell columnar carbon was put into 300 g of hydrogen peroxide with a mass concentration of 20 wt%, reacted at 60° C. for 2 h, filtered, washed to neutrality, and dried at 120° C. for 12 h to obtain modified coconut shell columnar carbon;

[0046] (2) Then, the modified coconut shell columnar carbon, nickel chloride and calcium acetate obtained in step (1) were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 14 h, dried at 140 ° C. for 12 h, and calcined at 550 ° C. for 3 h to obtain product A;

[0047] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 14 h, dried at 140 °C for 12 h, and calcined at 550 °C for 3 h; then reduced at 300 °C for 2 h in a hydrogen atmosphere to obtain a supported catalyst.

[0048] Example 3

[0049] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: room temperature; reaction pressure: 0.5Mpa; reaction time: 2h.

[0050] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 1wt%; the loading amount of Ca is 2.5wt%; the loading amount of Pt is 0.5wt%; and the loading amount of Ir is 0.7wt%.

[0051] The molar ratio of HCOONa to ammonia water is 1:2; the molar ratio of the acid binding agent to the raw material is 1:1; the mass ratio of the solvent to the raw material is 1:1; and the mass ratio of the supported catalyst to the raw material is 0.01%.

[0052] The preparation method of the supported catalyst is as follows:

[0053] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 200° C., the activation time was 16 h, the activated coconut shell columnar carbon was put into 200 g of hydrogen peroxide with a mass concentration of 10 wt%, reacted at 40° C. for 4 h, filtered, washed to neutrality, and dried at 80° C. for 18 h to obtain modified coconut shell columnar carbon;

[0054] (2) Then the modified coconut shell columnar carbon, nickel acetate and calcium nitrate obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 10 h, dried at 100 ° C. for 24 h, and calcined at 450 ° C. for 7 h to obtain product A;

[0055] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in deionized water, allowed to stand for 10 hours, dried at 100°C for 24 hours, and calcined at 450°C for 7 hours; and then reduced at 200°C for 4 hours under a hydrogen atmosphere to obtain a supported catalyst.

[0056] Comparative Example 1

[0057] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa as an acid-binding agent, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0058] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0059] The molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0060] The preparation method of the supported catalyst is as follows:

[0061] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0062] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0063] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0064] Comparative Example 2

[0065] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa as an acid-binding agent, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0066] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0067] The molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0068] The preparation method of the supported catalyst is as follows:

[0069] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0070] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0071] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0072] Comparative Example 3

[0073] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0074] The carrier of the supported catalyst is coconut shell columnar carbon; the auxiliary agent is Ni; the active components are Pt and Ir. Based on the mass of coconut shell columnar carbon: the loading amount of Ni is 3.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0075] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0076] The preparation method of the supported catalyst is as follows:

[0077] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0078] (2) Then the modified coconut shell columnar carbon and nickel nitrate obtained in step (1) were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0079] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0080] Comparative Example 4

[0081] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0082] The carrier of the supported catalyst is coconut shell columnar carbon: the auxiliary agent is Ca, and the active components are Pt and Ir. Based on the mass of coconut shell columnar carbon: the loading amount of Ca is 3.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0083] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0084] The preparation method of the supported catalyst is as follows:

[0085] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0086] (2) Then the modified coconut shell columnar carbon obtained in step (1) and calcium chloride are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0087] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0088] Comparative Example 5

[0089] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0090] The carrier of the supported catalyst is coconut shell columnar carbon; the additives are Ni and Ca, and the active component is Pt. Based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; and the loading amount of Pt is 1.4wt%.

[0091] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0092] The preparation method of the supported catalyst is as follows:

[0093] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0094] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0095] (3) The obtained product A and chloroplatinic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h in a hydrogen atmosphere to obtain a supported catalyst.

[0096] Comparative Example 6

[0097] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0098] The carrier of the supported catalyst is coconut shell columnar carbon; the additives are Ni and Ca, and the active component is Ir. Based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; and the loading amount of Ir is 1.4wt%.

[0099] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0100] The preparation method of the supported catalyst is as follows:

[0101] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 12 h, the activated coconut shell columnar carbon was put into 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50° C. for 3 h, filtered, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0102] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0103] (3) The obtained product A and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h in a hydrogen atmosphere to obtain a supported catalyst.

[0104] Comparative Example 7

[0105] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0106] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0107] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0108] The preparation method of the supported catalyst is as follows:

[0109] (1) 100 g of coconut shell columnar carbon was put into an activation furnace for activation, the activation gas was water vapor, the activation temperature was 250° C., the activation time was 13 h, washed to neutrality, and dried at 100° C. for 16 h to obtain modified coconut shell columnar carbon;

[0110] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0111] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0112] Comparative Example 8

[0113] A method for preparing 2,3-dichloropyridine, using 2,3,6-trichloropyridine as a raw material, a high-pressure reactor as a reaction vessel, HCOONa and ammonia water as acid binding agents, methanol as a solvent, in the presence of a supported catalyst, hydrogenation reaction to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: 40°C; reaction pressure: 0.2Mpa; reaction time: 6h.

[0114] The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of coconut shell columnar carbon: the loading amount of Ni is 2wt%; the loading amount of Ca is 1.5wt%; the loading amount of Pt is 1wt%; and the loading amount of Ir is 0.4wt%.

[0115] The molar ratio of HCOONa to ammonia water is 1:3; the molar ratio of the acid binding agent to the raw material is 1.5:1; the mass ratio of the solvent to the raw material is 6:1; and the mass ratio of the supported catalyst to the raw material is 0.25%.

[0116] The preparation method of the supported catalyst is as follows:

[0117] (1) 100 g of coconut shell columnar carbon was placed in 250 g of hydrogen peroxide with a mass concentration of 15 wt%, reacted at 50 ° C for 15 h, filtered, washed to neutrality, and dried at 100 ° C for 16 h to obtain modified coconut shell columnar carbon;

[0118] (2) Then the modified coconut shell columnar carbon, nickel nitrate and calcium chloride obtained in step (1) are ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 ° C. for 18 h, and calcined at 500 ° C. for 5 h to obtain product A;

[0119] (3) The obtained product A, chloroplatinic acid and chloroiridic acid were ultrasonically dispersed in 100 mL of deionized water, allowed to stand for 12 h, dried at 120 °C for 18 h, and calcined at 500 °C for 5 h; then reduced at 250 °C for 3 h under a hydrogen atmosphere to obtain a supported catalyst.

[0120] The yields of 2,3-dichloropyridine of Example 1-3 and Comparative Example 1-8 were measured. The specific results are shown in Table 1:

[0121] Table 1

[0122] Yield (%) Yield (%) Example 1 80.6 Comparative Example 4 77.9 Example 2 79.5 Comparative Example 5 78.5 Example 3 80.2 Comparative Example 6 78.2 Comparative Example 1 76.8 Comparative Example 7 77.4 Comparative Example 2 75.6 Comparative Example 8 77.1 Comparative Example 3 77.3

[0123] It can be seen from Table 1 that the 2,3-dichloropyridine obtained by the preparation method of the present invention has an excellent yield and has excellent application prospects.

[0124] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing 2,3-dichloropyridine, characterized in that: 2,3,6-trichloropyridine is used as a raw material, HCOONa and ammonia water are used as acid-binding agents, and methanol is used as a solvent. In the presence of a supported catalyst, a hydrogenation reaction is performed to obtain 2,3-dichloropyridine. The reaction conditions are: reaction temperature: room temperature to 500° C.; reaction pressure: 0.1 to 1 MPa; reaction time: 2 to 10 hours; The carrier of the supported catalyst is coconut shell columnar carbon: the additives are Ni and Ca, the active components are Pt and Ir, and based on the mass of the coconut shell columnar carbon: the loading amount of Ni is 1-3wt%; the loading amount of Ca is 0.5-2.5wt%; the loading amount of Pt is 0.5-1.5wt%; the loading amount of Ir is 0.1-0.7wt%; The molar ratio of HCOONa to ammonia water is 1:2-4; the molar ratio of the acid binding agent to the raw material is 1-2:1; The preparation method of the supported catalyst is as follows: (1) putting coconut shell columnar carbon into an activation furnace for activation, placing the activated coconut shell columnar carbon into hydrogen peroxide for reaction, filtering, washing to neutrality, and drying to obtain modified coconut shell columnar carbon; (2) then ultrasonically dispersing the modified coconut shell columnar carbon, the nickel source and the calcium source into deionized water, standing, drying and calcining to obtain product A; (3) ultrasonically dispersing the obtained product A, platinum source and iridium source into deionized water, standing, drying, calcining, and then reducing at 200-300° C. for 2-4 hours in a hydrogen atmosphere to obtain a supported catalyst; In step (1), the activation conditions are: the activation gas is water vapor, the activation temperature is 200-300° C., and the activation time is 8-16 hours; In step (1), the mass concentration of the hydrogen peroxide is 10-20wt%; the reaction is carried out at 40-60°C for 2-4h; the mass ratio of the coconut shell columnar charcoal to the hydrogen peroxide is 1:2-3; and the drying is carried out at 80-120°C for 12-18h.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the solvent to the raw material is 1-10:1; the mass ratio of the supported catalyst to the raw material is 0.01-0.5%.

3. The preparation method according to claim 1, characterized in that: In step (2), the standing time is 10 to 14 hours; the drying is performed at 100 to 140° C. for 12 to 24 hours; and the calcination is performed at 450 to 550° C. for 3 to 7 hours.

4. The preparation method according to claim 1, characterized in that: In step (3), the standing time is 10 to 14 hours; the drying is performed at 100 to 140° C. for 12 to 24 hours; and the calcination is performed at 450 to 550° C. for 3 to 7 hours.

5. The preparation method according to claim 1, characterized in that: In step (3), the reduction condition is: reduction at 200-300° C. for 2-4 hours in a hydrogen atmosphere.

6. The preparation method according to claim 1, characterized in that: The nickel source is at least one of nickel nitrate, nickel chloride and nickel acetate; the calcium source is at least one of calcium nitrate, calcium chloride and calcium acetate; the platinum source is chloroplatinic acid; and the iridium source is chloroiridic acid.