Preparation method of chloropyridine

Abstract

The invention provides a preparation method of chloropyridine. The preparation method comprises the following steps: in an oxidizing atmosphere, pyridine and chlorine-containing gas are subjected to a chlorination reaction under the action of a catalyst, and a reaction product comprises chloropyridine; the catalyst comprises an active component and a carrier, wherein the carrier comprises any one or more of a porous metal oxide and a microporous molecular sieve. The method has the advantages of high chloropyridine yield, high process continuity and high flexibility.

Description

Technical Field

[0001] This application belongs to the field of chemical engineering, and particularly relates to a preparation method of chloropyridine. Background Art

[0002] Chloropyridine is a pyridine derivative substituted with chlorine atoms, and has a wide range of application fields and important industrial value. Among them, 2,3,5,6-tetrachloropyridine is an intermediate of fluroxypyr and chlorpyrifos; 2,3,6-trichloropyridine is an important intermediate of chlorantraniliprole and cyantraniliprole; 2,6-dichloropyridine can be used to prepare triazole and imidazole potassium channel antagonists and is used as an antiarrhythmic drug.

[0003] Gas-solid phase catalytic chlorination is a common method for preparing chloropyridine. Usually, the raw materials pyridine and chlorine gas are loaded into a fixed-bed reactor equipped with a solid catalyst for reaction. The composition, physical and chemical properties, relative dosage, etc. of the catalyst are closely related to the reaction path and product yield. For example, the Chinese patent application with the publication number CN110256334A provides a method for obtaining 2-chloropyridine, 2,6-dichloropyridine, 2,3,6-trichloropyridine, 2,3,5-trichloropyridine, 2,3,5,6-tetrachloropyridine and pentachloropyridine through multi-stage catalytic chlorination reactions. Different catalysts with different active ingredients and ratios are required for each stage of catalytic chlorination reaction, which can obtain a relatively high raw material utilization rate. However, its disadvantage is that the time cost for producing chloropyridine is relatively high, and the operation simplicity and flexibility are relatively low.

[0004] Currently, there is still a lack of a flexible and efficient method for gas-solid phase catalytic chlorination to prepare chloropyridine. Summary of the Invention

[0005] In view of the problems of low yield of chloropyridine, insufficient process continuity and flexibility in the above-mentioned prior art, the present invention provides a preparation method of chloropyridine, including:

[0006] Under an oxidizing atmosphere, pyridine and a chlorine-containing gas are subjected to a chlorination reaction under the action of a catalyst, and the reaction product includes chloropyridine; the catalyst includes an active ingredient and a carrier, and the carrier includes any one or more of porous metal oxides and microporous molecular sieves.

[0007] Through the above preparation method, various chloropyridine products including 2,6-dichloropyridine, 2,3,6-trichloropyridine and 2,3,5,6-tetrachloropyridine can be obtained simultaneously, and the process has relatively high continuity. When the above chlorination reaction is carried out under an oxidizing atmosphere in combination with the above-mentioned oxidation-resistant catalyst carrier, the yield of chloropyridine can be effectively improved; at the same time, according to the selectivity difference of different compositions of the catalyst for chloropyridine, the yield of the target product can be flexibly and conveniently improved.

[0008] In any embodiment, the above oxidation atmosphere contains oxygen and a protective gas; optionally, the protective gas includes nitrogen, carbon dioxide, or an inert gas, and the inert gas includes one or more of helium, neon, or argon.

[0009] In any embodiment, the above oxidation atmosphere is formed by introducing air and a protective gas, and the volume fraction of oxygen in the oxidation atmosphere is 2% - 10%.

[0010] In any embodiment, the chlorine-containing gas includes chlorine gas and / or hydrogen chloride gas; optionally, the molar ratio of pyridine to chlorine element in the chlorine-containing gas is 1:(6 - 12).

[0011] In any embodiment, the weight hourly space velocity of pyridine is 0.03 h -1 -0.16 h -1 , and it can be optionally 0.07 h -1 -0.10 h -1 .

[0012] In any embodiment, the chlorinated pyridine includes one or more of 2,6-dichloropyridine, 2,3,6-trichloropyridine, and 2,3,5,6-tetrachloropyridine.

[0013] In any embodiment, the porous metal oxide includes one or more of alumina, silica, or zirconia.

[0014] In any embodiment, the above porous metal oxide has one or more of the following characteristics:

[0015] (1) The pore volume of the porous metal oxide is 0.3 mL / g - 1 mL / g;

[0016] (2) The particle size distribution of the porous metal oxide is in the range of 3 mm - 20 mm, and preferably the particle size distribution is in the range of 3 mm - 8 mm;

[0017] (3) The BET specific surface area of the porous metal oxide is 150 m 2 / g - 350 m 2 / g.

[0018] In any embodiment, the above microporous molecular sieve is selected from any one or more of 5A molecular sieve, 13X molecular sieve, NaY molecular sieve, and ZSM-5 molecular sieve.

[0019] In any embodiment, the active components of the catalyst include transition metal elements and / or rare earth elements. The transition metal elements can be optionally any one or more of copper, cobalt, iron, chromium, and tungsten, and the rare earth elements can be optionally any one or more of cerium and lanthanum; preferably, the active components of the catalyst include any one or more of copper element, chromium element, and cerium element.

[0020] In any embodiment, based on the metal elements in the active ingredient, the loading amount of the active ingredient in the catalyst is 2% - 15%, optionally 2% - 12%, and further optionally 3% - 11%.

[0021] In any embodiment, the catalyst further comprises a promoter, and the promoter comprises an alkali metal element or an alkaline earth metal element. The alkali metal element can be any one or more of potassium and sodium, and the alkaline earth metal element is selected from any one or more of magnesium, strontium, calcium or barium; preferably, the promoter comprises potassium element and / or magnesium element.

[0022] In any embodiment, the temperature of the chlorination reaction is 310°C - 430°C, optionally 360°C - 410°C.

[0023] In any embodiment, the pressure of the chlorination reaction is less than or equal to 1 MPa, preferably less than or equal to 0.5 MPa. Detailed Embodiments

[0024] The following further describes in detail the embodiments of the present application in conjunction with the examples. The detailed descriptions of the following examples are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described examples.

[0025] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0026] If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0027] Unless otherwise explicitly stated, all materials and reagents used in this disclosure are commercially available.

[0028] In the present application, the term "about" means that the value it limits can have a deviation within the range of ±10% of the value. For example, the term "about 100°C" means the range of "100 ± 10°C".

[0029] In the present application, the term "atmospheric pressure" means about 1 atmosphere.

[0030] In the present application, the term "room temperature" means 20°C - 25°C, preferably 25°C.

[0031] The present invention provides a method for preparing chloropyridine, comprising: under an oxidizing atmosphere, subjecting pyridine and a chlorine-containing gas to a chlorination reaction under the action of a catalyst, and the reaction product comprises chloropyridine; the catalyst comprises an active ingredient and a carrier, and the carrier comprises any one or more of porous metal oxides and microporous molecular sieves.

[0032] Through the above preparation method, various chlorinated pyridine products including 2,6-dichloropyridine, 2,3,6-trichloropyridine and 2,3,5,6-tetrachloropyridine can be obtained simultaneously. In particular, the applicant has found that when the above chlorination reaction is carried out in an oxidative atmosphere in combination with the above oxidation-resistant catalyst support, the yield of chlorinated pyridine can be effectively improved; at the same time, according to the selectivity differences of catalysts with different compositions for chlorinated pyridine, the yield of the target products 2,6-dichloropyridine, 2,3,6-trichloropyridine or 2,3,5,6-tetrachloropyridine can be flexibly and conveniently increased.

[0033] The above reaction process can be carried out in a fixed-bed reactor or a continuous-flow reactor, which is beneficial to improving the reaction efficiency.

[0034] In some embodiments, the oxidative atmosphere contains oxygen and a protective gas. By way of example and not limitation, air can be continuously introduced into the reactor to provide oxygen, and the relative content of the two can be adjusted by controlling the flow rates of air and the protective gas. Using air to provide the oxidative atmosphere realizes the low-cost operation of the preparation method.

[0035] As the name implies, the protective gas refers to a gas that can stably exist and does not participate in the reaction in the chlorination reaction system of the present application. In some embodiments, the above protective gas includes nitrogen, carbon dioxide or inert gases, and the inert gases include one or more of helium, neon or argon. The above protective gas can be used as the carrier gas of pyridine to feed pyridine into the reactor.

[0036] In some embodiments, an oxidative atmosphere is formed by introducing air and a protective gas, and the volume fraction of oxygen in the oxidative atmosphere is 2%-10%, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% or any range formed by any two of them. When the volume fraction of oxygen is within the above range, it is beneficial to improve the yield of chlorinated pyridine products.

[0037] In some embodiments, the chlorine-containing gas includes chlorine gas and / or hydrogen chloride gas. The ratio of pyridine to the chlorine-containing gas in the present application can refer to conventional techniques, and the chlorine-containing gas is in relative excess to increase the conversion rate of pyridine. Optionally, in some embodiments, the molar ratio of pyridine to chlorine in the chlorine-containing gas is 1:(6-12). By way of example and not limitation, the molar ratio of pyridine to chlorine in the chlorine-containing gas can be 1:6, 1:7, 1:7.3, 1:8, 1:8.8, 1:9, 1:9.7, 1:10 or 1:12 or any range formed by any two of them.

[0038] In some embodiments, the weight hourly space velocity of pyridine is 0.03h -1 -0.16h -1 and can be optionally 0.07h -1-0.10h -1 The raw material pyridine can enter the reactor together with the carrier gas after being preheated and vaporized, or the carrier gas can be used to blow the tiny droplets containing pyridine into the reactor.

[0039] Since it is difficult to precisely control the chlorination progress in the chlorination reaction of pyridine and chlorine-containing gas, the product is usually a mixture of chloropyridines. In some embodiments, the chloropyridines include one or more of 2,6-dichloropyridine, 2,3,6-trichloropyridine, and 2,3,5,6-tetrachloropyridine. The selectivity to different chloropyridines can be adjusted by adjusting parameters such as the temperature, pressure, and gas flow rate of the chlorination reaction.

[0040] In some embodiments, the porous metal oxide includes one or more of alumina, silica, or zirconia. Preferably, the porous metal oxide has one or more of the following characteristics: (1) the pore volume of the porous metal oxide is 0.3 mL / g - 1 mL / g; (2) the particle size distribution of the porous metal oxide ranges from 3 mm to 20 mm, preferably from 3 mm to 8 mm; (3) the BET specific surface area of the porous metal oxide is 150 m 2 / g - 350 m 2 / g. The porous metal oxide with the above pore volume or BET specific surface area provides a sufficient loading area for the loading of the active ingredient; the porous metal oxide with the above particle size distribution can be fully dispersed in the chlorination reaction, is not easy to agglomerate, and is conducive to the exertion of the catalytic effect.

[0041] The above microporous molecular sieve can be selected from conventional microporous molecular sieves. In some embodiments, the microporous molecular sieve is selected from any one or more of 5A molecular sieve, 13X molecular sieve, NaY molecular sieve, and ZSM-5 molecular sieve.

[0042] Any active ingredient conventionally used for catalyzing the chlorination reaction of pyridine and chlorine-containing gas can be considered for application in the present invention. In some embodiments, the active ingredient of the catalyst includes transition metal elements and / or rare earth elements. The transition metal elements can be any one or more of copper, cobalt, iron, chromium, and tungsten, and the rare earth elements can be any one or more of cerium and lanthanum. The catalytic activities of different active ingredients are different, but they are all beneficial to improving the overall yield of chloropyridines in the oxidation atmosphere of the present application. Further, the active ingredient of the catalyst preferably includes any one or more of copper element, chromium element, and cerium element. By way of example and not limitation, the active ingredient of the catalyst can be chlorides, oxides, or chlorooxides containing the aforementioned transition metal elements or rare earth elements.

[0043] In some embodiments, based on the metal elements in the active component, the loading amount of the active component in the catalyst is 2% - 15%, such as 2%, 3%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14% or 15%, or the range formed by any two of them. Optionally, it is 2% - 12%, and further optionally 3% - 11%.

[0044] In some embodiments, the active component of the catalyst is copper element. Based on the metal elements in the active component, the loading amount of the active component in the catalyst is optionally 4% - 10%.

[0045] In some embodiments, the active component of the catalyst is chromium element. Based on the metal elements in the active component, the loading amount of the active component in the catalyst is optionally 3% - 7%.

[0046] In some embodiments, the active component of the catalyst is cerium element. Based on the metal elements in the active component, the loading amount of the active component in the catalyst is optionally 5% - 11%.

[0047] In some embodiments, the catalyst further includes a promoter. The promoter can be a structural promoter or a modulating promoter.

[0048] In some embodiments, the promoter includes an alkali metal element or an alkaline earth metal element. The alkali metal element can be any one or more of potassium and sodium, and the alkaline earth metal element is selected from any one or more of magnesium, strontium, calcium or barium. Further, the aforementioned promoter preferably includes potassium element and / or magnesium element.

[0049] Such promoters including alkali metal elements or alkaline earth metal elements can exhibit one or more of the following effects: adjusting the acidity of the catalyst and inhibiting carbon deposition; forming a metal melt with the active component to improve the thermal stability of the active component; changing the electronic structure of the active component through interaction with the active component to improve the catalytic activity.

[0050] In the present invention, both the temperature and pressure of the chlorination reaction can refer to the conventional chlorination reaction conditions. In some embodiments, the temperature of the chlorination reaction is 310°C - 430°C, and optionally 360°C - 410°C. By way of example and not limitation, the temperature of the chlorination reaction can be 310°C - 410°C, or 360°C - 430°C, or 380°C - 420°C, or 400°C - 430°C.

[0051] In some embodiments, the pressure of the chlorination reaction is less than or equal to 1 MPa. Further, the pressure of the aforementioned chlorination reaction is less than or equal to 0.5 MPa. The above pressure is mainly determined by the gas introduced in the reaction and the reaction temperature, and no additional adjustment is required.

[0052] The beneficial effects of the present application will be further described below in conjunction with examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0053] Example 1

[0054] Step 1: At room temperature, dissolve 5 g of CuCl2 (134.35 g / mol) in 71 g of water, add 95 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 hours to obtain a 5% CuCl2 / Al2O3 catalyst. 5% represents the mass content of CuCl2 in the catalyst (the same below). Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 2.4%;

[0055] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0056] Step 2: Weigh 88 g of the above catalyst and load it into a fixed-bed reactor. Vaporize pyridine in a preheater at a flow rate of 0.12 mL / min, and then send the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 9500 mL / min, and the weight hourly space velocity of pyridine is 0.08 h -1 , while introducing chlorine gas to react with pyridine on the catalyst bed. The flow rate of chlorine gas is 160 mL / min, and the molar ratio of pyridine to chlorine gas is 1:4.86. Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 1%, the reaction temperature is 310°C - 410°C, the reaction pressure is maintained at 0.5 MPa, and the reaction duration is 24 h;

[0057] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content by high-performance liquid chromatography to calculate the pyridine conversion rate and the yields of various products. The results are shown in Table 1.

[0058] Example 2

[0059] Step 1: At room temperature, dissolve 3 g of KCl and 20 g of CuCl2 (134.35 g / mol) in 62 g of water, add 77 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 h to obtain a 3% KCl - 20% CuCl2 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 9.4%;

[0060] The pore volume of the porous alumina is 0.5 mL / g, the particle size distribution ranges from 3 mm to 8 mm, and the BET specific surface area is 230 m 2 / g;

[0061] Step 2: Weigh 66 g of the above catalyst and load it into a fixed-bed reactor. Feed pyridine into a preheater for vaporization at a flow rate of 0.09 mL / min, and then feed the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 3000 mL / min, and the weight hourly space velocity of pyridine is 0.08 h -1 , while introducing chlorine gas to react with pyridine on the catalyst bed. The flow rate of chlorine gas is 120 mL / min, and the molar ratio of pyridine to chlorine gas is 1:4.86. Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 4%, the reaction temperature is 360°C - 430°C, the reaction pressure is maintained at 0.3 MPa, and the reaction duration is 24 h;

[0062] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content using high-performance liquid chromatography to calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 1.

[0063] Example 3

[0064] The difference between this example and Example 2 is only in Step 2:

[0065] Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 3%;

[0066] Other operations in Step 2 are the same as those in Example 2;

[0067] Except for the above Step 2, the remaining steps and settings are the same as those in Example 2. The results of the pyridine conversion rate and the yields of each product are shown in Table 1.

[0068] Example 4

[0069] The difference between this example and Example 2 is only in Step 2:

[0070] Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 2%;

[0071] Other operations in Step 2 are the same as those in Example 2;

[0072] Except for the above Step 2, the remaining steps and settings are the same as those in Example 2. The results of the pyridine conversion rate and the yields of each product are shown in Table 1.

[0073] Example 5

[0074] The difference between this example and Example 2 lies only in Step 2:

[0075] Air is continuously introduced during the reaction to form an oxidizing atmosphere in the reactor, and the volume fraction of O2 in this oxidizing atmosphere is 7%;

[0076] Other operations in Step 2 are the same as those in Example 2;

[0077] Except for the above Step 2, the remaining steps and settings are the same as those in Example 2, and the results of pyridine conversion rate and the yields of various products are shown in Table 1.

[0078] Example 6

[0079] The difference between this example and Example 2 lies only in Step 2:

[0080] Air is continuously introduced during the reaction to form an oxidizing atmosphere in the reactor, and the volume fraction of O2 in this oxidizing atmosphere is 11%;

[0081] Other operations in Step 2 are the same as those in Example 2;

[0082] Except for the above Step 2, the remaining steps and settings are the same as those in Example 2, and the results of pyridine conversion rate and the yields of various products are shown in Table 1.

[0083] Comparative Example 1

[0084] The difference between this comparative example and Example 1 lies only in Step 2:

[0085] Air is not introduced during the reaction, and there is no oxygen in the reactor;

[0086] Other operations in Step 2 are the same as those in Example 1;

[0087] Except for the above Step 2, the remaining steps and settings are the same as those in Example 1, and the results of pyridine conversion rate and the yields of various products are shown in Table 1.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 1 is as follows:

[0090] Step 1: At room temperature, 1 g of KCl and 5 g of CuCl2 (134.35 g / mol) are dissolved in 71 g of water, and 94 g of porous alumina is added;

[0091] Other operations in Step 1 are the same as those in Example 1 to prepare a 1% KCl - 5% CuCl2 / Al2O3 catalyst. Calculated by the metal elements in the active components, the loading amount of the active components of the catalyst is 2.4%;

[0092] Step 2: No air is introduced during the reaction process, and there is no oxygen in the reactor;

[0093] Other operations in Step 2 and Step 3 are the same as those in Example 1. The results of pyridine conversion rate and yields of various products are shown in Table 1.

[0094] Comparative Example 3

[0095] The difference between this comparative example and Example 2 is only in Step 2:

[0096] No air is introduced during the reaction process, and there is no oxygen in the reactor;

[0097] Other operations in Step 2 are the same as those in Example 2;

[0098] Except for the above Step 2, the remaining steps and settings are the same as those in Example 2. The results of pyridine conversion rate and yields of various products are shown in Table 1.

[0099] For the convenience of analyzing and comparing the above examples and comparative examples, the differences in catalysts, reaction raw materials, and reaction conditions are presented together in Table 1.

[0100] Table 1

[0101]

[0102]

[0103] Generally, considering that the active components or carriers of the catalyst are easily oxidized and deactivated under high-temperature conditions, pyridine and chlorine need to react under anaerobic conditions to produce chloropyridine. According to the data in Table 1, it can be found that using the above-mentioned porous alumina as the carrier and conducting gas-solid catalytic chlorination reaction to prepare chloropyridine under an oxidative atmosphere can obtain significantly improved yields of chloropyridine compared with those under anaerobic conditions. For example, comparing the product yields of Example 1 and Comparative Example 1, in Example 1, by introducing O2 with a volume fraction of 1% into the reaction atmosphere, a total yield of chloropyridine better than that of Comparative Example 1 (using a catalyst with the same loading amount under anaerobic conditions) can be obtained.

[0104] Example 7

[0105] Step 1: At room temperature, dissolve 11 g of CuCl2 (134.35 g / mol) in 71 g of water, add 89 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 hours to obtain an 11% CuCl2 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 5.2%;

[0106] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0107] Step 2: Weigh 15 g of the above catalyst and load it into a fixed-bed reactor. Feed pyridine into the preheater for vaporization at a flow rate of 0.05 mL / min, and then feed the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 2500 mL / min, and the weight hourly space velocity of pyridine is 0.2 h -1 , while introducing chlorine gas to react with pyridine on the catalyst bed. The flow rate of chlorine gas is 50 mL / min, and the molar ratio of pyridine to chlorine gas is 1:3.64. Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 3%, the reaction temperature is 400°C - 430°C, the reaction pressure is maintained at 0.3 MPa, and the reaction duration is 24 h;

[0108] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content using high-performance liquid chromatography to calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 2.

[0109] Examples 8 to 12

[0110] Compared with Example 7, the difference in the above examples is only in Step 1:

[0111] Examples 8 to 12 respectively use 11 g of different active ingredients to prepare the catalyst. Furthermore, calculated by the metal element, the loadings of the active ingredients in the catalysts of the above examples are also different;

[0112] The remaining settings are the same as those in Example 7. The results of the pyridine conversion rate and the yields of each product are shown in Table 2.

[0113] Example 13

[0114] The difference between this example and Example 7 is only in Step 1:

[0115] Dissolve 11 g of WCl6 (396.54 g / mol) in 71 g of ethanol. The remaining settings are the same as those in Example 7 to prepare an 11% WCl6 / Al2O3 catalyst. Calculated by the metal element in the active ingredient, the loading of the active ingredient in the catalyst is 5.1%;

[0116] Step 2 and Step 3 are the same as those in Example 7. The results of pyridine conversion rate and the yields of various products are shown in Table 2. For easy analysis and comparison, the differences between Examples 7 to 13 are presented in Table 2. It can be found that for the seven catalysts with different active components in Table 2, a pyridine conversion rate higher than 80% can be achieved, and there are differences in the selectivity for the three chloropyridine products. Among them, copper chloride as the active component can obtain relatively better pyridine conversion rate and total yield of chloropyridine.

[0117] Table 2

[0118]

[0119] Examples 14 to 17

[0120] Compared with Example 1, the difference is only in Step 1:

[0121] Examples 14 to 17 respectively use catalysts with different mass contents of CuCl2. Furthermore, in terms of the metal element, the loadings of the active components in the catalysts of the above examples are also different;

[0122] The remaining settings are the same as those in Example 1. The results of pyridine conversion rate and the yields of various products are shown in Table 3.

[0123] For easy analysis and comparison, the differences between Examples 14 to 17 are presented in Table 3.

[0124] Table 3

[0125]

[0126] Taking CuCl2 as the exemplary active component, Table 3 can, to a certain extent, reflect the influence of the change in the loading of the active component of the catalyst on the yield of chloropyridine.

[0127] As the mass content of CuCl2 in the catalyst increases, that is, the loading of the active component of the catalyst increases, the yield of 2,6-dichloropyridine shows a "U-shaped" non-monotonic change trend of first decreasing and then increasing, and the yield of 2,3,6-trichloropyridine continuously increases. In terms of the metal element in the active component, when the loading of the active component in the catalyst increases from 9.4% (Example 16) to 11.8% (Example 17), the yields of 2,6-dichloropyridine and 2,3,6-trichloropyridine increase. However, the yields of 2,3,5,6-tetrachloropyridine and the total yield of chloropyridine both show a slight decrease. Therefore, controlling the loading of the active component in the catalyst within the range of 2% - 10% has more cost advantages. Further, controlling the loading within the range of 4% - 10% can better balance the economic cost and catalytic effect.

[0128] Examples 18 to 22

[0129] Compared with Example 1, the difference is only in Step 1:

[0130] At room temperature, 1 g of additive X and 20 g of CuCl2 (134.35 g / mol) were dissolved in 71 g of water, and 79 g of porous alumina was added to prepare a 1% X-20% CuCl2 / Al2O3 catalyst. Among them, additive X is a chloride containing an alkali metal element or an alkaline earth metal element, and the additive X in Examples 16 to 20 is different from each other;

[0131] The remaining settings are the same as those in Example 1, and the results of pyridine conversion rate and the yields of each product are shown in Table 4.

[0132] For easy analysis and comparison, the differences between Example 16 (without additive, and the remaining settings are the same as those in Examples 18 to 22) and Examples 18 to 22 (different additives) are presented in Table 4.

[0133] Table 4

[0134]

[0135] It can be found from Table 4 that using a compound containing an alkali metal or an alkaline earth metal element as an additive in the catalyst may have the following two advantages: (1) It is beneficial to improve the total yield of chloropyridine. For example, compared with Example 16, the total yields of chloropyridine in Examples 18 and 19 increased by 13.02% and 3.81% respectively; (2) Based on the different selectivities of chloropyridine products exhibited by different additives, it is allowed to flexibly adjust the catalyst type as needed to prepare specific types of chloropyridine. For example, by selecting an additive containing Mg or Ba, a relatively high yield of 2,6-dichloropyridine can be obtained; by selecting an additive containing K or Mg, a relatively high yield of 2,3,6-trichloropyridine can be obtained; without using an additive, a relatively high yield of 2,3,5,6-tetrachloropyridine can be obtained.

[0136] Example 23

[0137] Step 1: At room temperature, 11 g of CuCl2 (134.35 g / mol) was dissolved in 71 g of water, and 89 g of porous alumina was added. After standing for 12 hours, it was dried at 80°C - 90°C for 12 hours, and then sent into a muffle furnace and calcined at 400°C for 5 hours to prepare an 11% CuCl2 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 5.2%;

[0138] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0139] Step 2: Weigh 40 g of the above catalyst and load it into a fixed-bed reactor. Feed pyridine into the preheater at a flow rate of 0.06 mL / min for vaporization, and then feed the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 1900 mL / min, and the weight hourly space velocity of pyridine is 0.09 h -1 , and simultaneously introduce chlorine gas to react with pyridine on the catalyst bed. The flow rate of chlorine gas is 100 mL / min, and the molar ratio of pyridine to chlorine gas is 1:6.07. Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 3%. The reaction temperature is 380°C - 420°C, the reaction pressure is maintained at 0.1 MPa, and the reaction duration is 24 h;

[0140] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content using high-performance liquid chromatography to calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 5.

[0141] Table 5

[0142]

[0143] Examples 24 to 29

[0144] Compared with Example 23, the difference is only in Step 1:

[0145] Examples 24 to 29 respectively use 89 g of other porous metal oxides or microporous molecular sieves as carriers to prepare catalysts. The exemplary process is as follows:

[0146] At room temperature, dissolve 11 g of CuCl2 in 71 g of water, and add 79 g of carrier Y to prepare an 11% CuCl2 / Y catalyst, where carrier Y is a porous metal oxide or microporous molecular sieve other than a porous alumina, and the carrier Y in Examples 24 to 29 is different from each other;

[0147] The remaining settings are the same as those in Example 23. The results of the pyridine conversion rate and the yields of each product are shown in Table 5.

[0148] For easy analysis and comparison, the differences between Examples 23 to 29 are presented in Table 5. It can be found from the data in Table 5 that different carrier-based selectivities for chloropyridine products are exhibited, allowing for flexible adjustment of the catalyst carrier type as needed to prepare specific types of chloropyridines.

[0149] Example 30

[0150] The difference between this example and Example 1 is that in Step 1, the active ingredient is replaced from CuCl2 to CrCl3. Specifically:

[0151] Step 1: At room temperature, dissolve 5 g of CrCl3 (158.355 g / mol) in 71 g of water, add 95 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 hours to obtain a 5% CrCl3 / Al2O3 catalyst. 5% represents the mass content of CrCl3 in the catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 1.6%;

[0152] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0153] The remaining steps are the same as those in Example 1. Calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 6.

[0154] Example 31

[0155] The difference between this example and Example 2 lies in Step 1, where the active component is replaced from CuCl2 to CrCl3. Specifically:

[0156] Step 1: At room temperature, dissolve 3 g of KCl and 20 g of CrCl3 (158.355 g / mol) in 62 g of water, add 77 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 h to obtain a 3% KCl - 20% CrCl3 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 6.6%;

[0157] The pore volume of the porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0158] The remaining steps are the same as those in Example 2. Calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 6.

[0159] Examples 32 to 35

[0160] Compared with Example 31, the difference lies only in Step 2:

[0161] In Examples 32 to 35, the volume fraction of O2 in the oxidizing atmosphere formed in the reactor is different, and the other operations and settings in Step 2 are the same as those in Example 31;

[0162] The remaining steps are the same as those in Example 31. The results of the pyridine conversion rate and the yields of each product are shown in Table 6.

[0163] Comparative Example 4

[0164] The difference between this comparative example and Example 30 is only in Step 2:

[0165] During the reaction process, air is not introduced, and there is no oxygen in the reactor;

[0166] Other operations in Step 2 are the same as those in Example 30;

[0167] Except for the above-mentioned Step 2, the remaining steps and settings are the same as those in Example 30, and the results of pyridine conversion rate and yields of various products are shown in Table 6.

[0168] Comparative Example 5

[0169] The difference between this comparative example and Example 30 is that:

[0170] In Step 1, at room temperature, 1 g of KCl and 5 g of CrCl3 (158.355 g / mol) are dissolved in 71 g of water, and 94 g of porous alumina is added;

[0171] Other operations in Step 1 are the same as those in Example 30, and a 1% KCl - 5% CrCl3 / Al2O3 catalyst is prepared. Calculated by the metal elements in the active components, the loading amount of the active components of the catalyst is 1.6%;

[0172] In Step 2, during the reaction process, air is not introduced, and there is no oxygen in the reactor;

[0173] Other operations in Step 2 and Step 3 are the same as those in Example 30, and the results of pyridine conversion rate and yields of various products are shown in Table 6.

[0174] Comparative Example 6

[0175] The difference between this comparative example and Example 31 is only in Step 2:

[0176] During the reaction process, air is not introduced, and there is no oxygen in the reactor;

[0177] Other operations in Step 2 are the same as those in Example 31;

[0178] Except for the above-mentioned Step 2, the remaining steps and settings are the same as those in Example 31, and the results of pyridine conversion rate and yields of various products are shown in Table 6.

[0179] Table 6

[0180]

[0181] According to the data in Table 6, it can be found that when the active ingredient is adjusted to CrCl3, using the above-mentioned porous alumina as the carrier and carrying out the gas-solid catalytic chlorination reaction in an oxidative atmosphere to prepare chloropyridine, compared with the case under anaerobic conditions (other settings remain the same), a significantly improved chloropyridine yield can also be obtained, indicating the universality of the above chloropyridine preparation method.

[0182] In particular, for Example 31, under the combined action of a small amount of oxygen (volume fraction of 4%) and the promoter KCl, a 2,3,6-trichloropyridine yield as high as 54.67% and a total chloropyridine yield as high as 94.94% can be obtained.

[0183] Examples 36 to 39

[0184] The difference between Examples 36 to 39 and Example 30 lies only in Step 1:

[0185] Catalysts with different mass contents of CrCl3 are respectively used. Furthermore, in terms of the metal element, the loading amount of the active ingredient in the catalysts of the above examples is also different;

[0186] The remaining settings are the same as those in Example 30, and the results of pyridine conversion rate and the yields of various products are shown in Table 7.

[0187] For the convenience of analysis and comparison, the differences between Examples 36 to 39 are presented in Table 7.

[0188] Table 7

[0189]

[0190] As the mass content of CrCl3 in the catalyst increases, that is, the loading amount of the active ingredient in the catalyst increases, the yield of 2,6-dichloropyridine shows a "U-shaped" non-monotonic change trend of first decreasing and then increasing, which is similar to the case where the active ingredient of the catalyst is CuCl2. In terms of the metal element in the active ingredient, when the loading amount of the active ingredient in the catalyst increases from 1.6% (Example 30) to 3.3% (Example 36), the yields of 2,6-dichloropyridine and 2,3,6-trichloropyridine and the total chloropyridine yield all increase significantly. However, when the loading amount of the active ingredient in the catalyst increases to 4.9%, the growth rate significantly slows down. With the continuous increase of the active ingredient loading amount, the yield of 2,3,6-trichloropyridine and the total chloropyridine yield even show a slight decrease.

[0191] Therefore, when using CrCl3 as the active ingredient of the catalyst, controlling the mass content of CrCl3 in the catalyst within the range of 3% - 8%, especially within the range of 4% - 7%, can better balance the economic cost and catalytic effect.

[0192] Examples 40 to 44

[0193] Examples 40 to 44 are different from Example 30 only in Step 1:

[0194] At room temperature, 1 g of additive X and 20 g of CrCl3 (158.355 g / mol) are dissolved in 71 g of water, and 79 g of porous alumina is added to prepare a 1% X-20% CrCl3 / Al2O3 catalyst, where the additive X is a chloride containing an alkali metal element or an alkaline earth metal element, and the additive X in Examples 40 to 44 is different from each other;

[0195] The remaining settings are the same as those in Example 30, and the results of the pyridine conversion rate and the yields of various products are shown in Table 8.

[0196] For easy analysis and comparison, the differences between Example 38 (without additive, and the remaining settings are the same as those in Examples 40 to 44) and Examples 40 to 44 (different additives) are presented in Table 8.

[0197] Table 8

[0198]

[0199] It can be seen from Table 8 that when the active component of the catalyst is CrCl3, the above additives can all significantly improve the yield of 2,3,6-trichloropyridine. Using KCl and BaCl2 as additives can obtain a relatively high yield of 2,6-dichloropyridine. Using KCl, MgCl2 and SrCl2 as additives can effectively improve the total yield of chloropyridine. For example, the total yields of chloropyridine in Examples 40 and 41 are increased by 9.22% and 5.59% respectively compared with Example 38. Without using an additive, a relatively high yield of 2,3,5,6-tetrachloropyridine can be obtained. The composition of the catalyst can be flexibly selected as needed based on the selectivity of the "additive + active component" combination for chloropyridine products.

[0200] Example 45

[0201] Step 1: At room temperature, 11 g of CrCl3 (158.355 g / mol) is dissolved in 71 g of water, and 89 g of porous alumina is added. After standing for 12 hours, it is dried at 80°C - 90°C for 12 hours, and then sent into a muffle furnace and calcined at 400°C for 5 hours to prepare an 11% CrCl3 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 3.6%;

[0202] The pore volume of the above porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0203] Step 2: Weigh 40 g of the above catalyst and load it into a fixed-bed reactor. Feed pyridine into the preheater at a flow rate of 0.06 mL / min for vaporization, and then feed the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 1900 mL / min, and the weight hourly space velocity of pyridine is 0.09 h -1 , and at the same time, feed chlorine gas, which reacts with pyridine on the catalyst bed. The flow rate of chlorine gas is 100 mL / min, and the molar ratio of pyridine to chlorine gas is 1:6.07. Continuously feed air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 3%, the reaction temperature is 380°C - 420°C, the reaction pressure is maintained at 0.1 MPa, and the reaction duration is 24 h;

[0204] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content using high-performance liquid chromatography. Calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 9.

[0205] Examples 46 and 51

[0206] Compared with Example 45, the difference is only in Step 1:

[0207] Examples 46 to 51 respectively use 89 g of other porous metal oxides or microporous molecular sieves as carriers to prepare catalysts. The exemplary process is as follows:

[0208] At room temperature, dissolve 11 g of CrCl3 in 71 g of water, add 79 g of carrier Y to obtain an 11% CrCl3 / Y catalyst, where carrier Y is a porous metal oxide or microporous molecular sieve other than a porous alumina, and the carrier Y in Examples 46 to 51 is different from each other;

[0209] The remaining settings are the same as those in Example 45. The results of the pyridine conversion rate and the yields of each product are shown in Table 9.

[0210] For easy analysis and comparison, the differences between Examples 45 to 51 are presented in Table 9. Using the same catalyst active component, different carriers can be selected to obtain different proportions of chloropyridine products, allowing for flexible adjustment of the catalyst carrier type as needed to prepare specific types of chloropyridines.

[0211] Table 9

[0212]

[0213]

[0214] Example 52

[0215] This example is similar to Example 1, but the active component is replaced from CuCl2 to CeCl3. Specifically:

[0216] Step 1: At room temperature, dissolve 5 g of CeCl3 (246.47 g / mol) in 71 g of water, add 95 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 hours to obtain a 5% CeCl3 / Al2O3 catalyst. 5% represents the mass content of CeCl3 in the catalyst (the same below). Calculated by the metal element in the active ingredient, the loading amount of the active ingredient of the catalyst is 2.8%;

[0217] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0218] The remaining steps are the same as those in Example 1. Calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 10.

[0219] Example 53

[0220] This example is similar to Example 2, replacing the active ingredient CuCl2 with CeCl3. Specifically:

[0221] Step 1: At room temperature, dissolve 3 g of KCl and 20 g of CeCl3 (246.47 g / mol) in 62 g of water, add 77 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 h to obtain a 3% KCl - 20% CeCl3 / Al2O3 catalyst. Calculated by the metal element in the active ingredient, the loading amount of the active ingredient of the catalyst is 11.4%;

[0222] The pore volume of the porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0223] The remaining steps are the same as those in Example 2. Calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 10.

[0224] Examples 54 to 57

[0225] Compared with Example 53, the difference is only in Step 2:

[0226] In Examples 54 to 57, the volume fraction of O2 in the oxidative atmosphere formed in the reactor is different, and the other operations and settings in Step 2 are the same as those in Example 53;

[0227] The remaining steps are the same as those in Example 53. The results of the pyridine conversion rate and the yields of each product are shown in Table 10.

[0228] Comparative Example 7

[0229] The difference between this comparative example and Example 52 is only in Step 2:

[0230] Air is not introduced during the reaction process, and there is no oxygen in the reactor;

[0231] Other operations in Step 2 are the same as those in Example 52;

[0232] Except for the above Step 2, the remaining steps and settings are the same as those in Example 52, and the results of pyridine conversion rate and product yields are shown in Table 10.

[0233] Comparative Example 8

[0234] The difference between this comparative example and Example 52 is only:

[0235] In Step 1, at room temperature, 1 g of KCl and 5 g of CeCl3 (246.47 g / mol) are dissolved in 71 g of water, and 94 g of porous alumina is added;

[0236] Other operations in Step 1 are the same as those in Example 52, and a 1% KCl - 5% CeCl3 / Al2O3 catalyst is prepared. Calculated by the metal elements in the active component, the loading amount of the active component of the catalyst is 2.8%;

[0237] In Step 2, air is not introduced during the reaction process, and there is no oxygen in the reactor;

[0238] Other operations in Step 2 and Step 3 are the same as those in Example 52, and the results of pyridine conversion rate and product yields are shown in Table 10.

[0239] Comparative Example 9

[0240] The difference between this comparative example and Example 53 is only in Step 2:

[0241] Air is not introduced during the reaction process, and there is no oxygen in the reactor;

[0242] Other operations in Step 2 are the same as those in Example 53;

[0243] Except for the above Step 2, the remaining steps and settings are the same as those in Example 53, and the results of pyridine conversion rate and product yields are shown in Table 10.

[0244] Table 10

[0245]

[0246] As can be seen from the data in Table 10, when the active ingredient is adjusted to CeCl3 and the above-mentioned porous alumina is used as the carrier, the gas-solid catalytic chlorination reaction is carried out in an oxidizing atmosphere to prepare chloropyridine. Compared with the case under anaerobic conditions (with other settings remaining the same), a significantly improved total yield of chloropyridine can also be obtained. In addition, introducing a certain volume fraction of oxygen alone or introducing a certain mass content of the additive alone is beneficial to increasing the yield of 2,3,6-trichloropyridine; introducing oxygen and the additive simultaneously can obtain a relatively higher proportion of 2,3,6-trichloropyridine and 2,3,5,6-tetrachloropyridine.

[0247] Examples 58 to 61

[0248] Compared with Example 52, the difference lies only in Step 1:

[0249] Examples 58 to 61 respectively use catalysts with different mass contents of CeCl3. Furthermore, in terms of the metal element in the active ingredient, the loading amount of the active ingredient in the catalysts of the above examples is also different;

[0250] The remaining settings are the same as those in Example 52, and the results of the pyridine conversion rate and the yields of various products are shown in Table 11.

[0251] For the convenience of analysis and comparison, the differences between Examples 58 to 61 are presented in Table 11.

[0252] Table 11

[0253]

[0254] The data in Table 11 show that the change in the loading amount of the active ingredient CeCl3 in the catalyst has a weak influence on the yield of 2,3,6-trichloropyridine, showing excellent selectivity for 2,3,5,6-tetrachloropyridine. Especially when the mass content of CeCl3 in the catalyst is 20% (Example 60), the yield of 2,3,5,6-tetrachloropyridine is as high as 54.14%. In addition, in terms of the metal element in the active ingredient, controlling the loading amount of the active ingredient CeCl3 in the catalyst within the range of 5% - 14%, especially within the range of 5% - 12%, can better balance the economic cost and the catalytic effect.

[0255] Examples 62 to 66

[0256] Compared with Example 52, the difference lies only in Step 1:

[0257] At room temperature, 1 g of promoter X and 20 g of CeCl3 (246.47 g / mol) were dissolved in 71 g of water, and 79 g of porous alumina was added to prepare a 1% X-20% CeCl3 / Al2O3 catalyst. Among them, promoter X is a chloride containing an alkali metal element or an alkaline earth metal element, and the promoter X in Examples 62 to 66 is different from each other;

[0258] The rest of the settings were the same as in Example 52, and the results of pyridine conversion rate and the yields of various products are shown in Table 12.

[0259] For easy analysis and comparison, the differences between Example 60 (without promoter, and the rest of the settings are the same as in Examples 62 to 66) and Examples 62 to 66 (different promoters) are presented in Table 12.

[0260] Table 12

[0261]

[0262] According to the data in Table 12, it can be known that when the active component of the catalyst is CeCl3, the above-mentioned promoters can all greatly improve the yield of 2,3,6-trichloropyridine, showing excellent selectivity for 2,3,6-trichloropyridine. Among them, the effects of KCl and MgCl2 are particularly prominent, having both excellent selectivity for 2,3,6-trichloropyridine and a total yield of up to about 94%.

[0263] Example 67

[0264] Step 1: At room temperature, 11 g of CeCl3 (246.47 g / mol) was dissolved in 71 g of water, and 89 g of porous alumina was added. After standing for 12 hours, it was dried at 80°C - 90°C for 12 hours, and then sent into a muffle furnace and calcined at 400°C for 5 hours to prepare an 11% CeCl3 / Al2O3 catalyst. Calculated by the metal element in the active component, the loading amount of the active component of the catalyst is 6.2%;

[0265] The pore volume of the above-mentioned porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0266] Step 2: Weigh 40 g of the above catalyst and load it into a fixed-bed reactor. Pyridine was vaporized in a preheater at a flow rate of 0.06 mL / min, and then the vaporized pyridine was sent into the reactor using N2 as the carrier gas. The flow rate of N2 is 1900 mL / min, and the weight hourly space velocity of pyridine is 0.09 h -1, while introducing chlorine gas simultaneously, reacting with pyridine on the catalyst bed. The flow rate of chlorine gas is 100 mL / min, and the molar ratio of pyridine to chlorine gas is 1:6.07. Air is continuously introduced during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 3%, the reaction temperature is 380°C - 420°C, the reaction pressure is maintained at 0.1 MPa, and the reaction duration is 24 h;

[0267] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition and content by high performance liquid chromatography to calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 13.

[0268] Table 13

[0269]

[0270] Examples 68 to 73

[0271] Compared with Example 67, the only difference lies in Step 1:

[0272] Examples 68 to 73 respectively use 89 g of other porous metal oxides or microporous molecular sieves as carriers to prepare catalysts. The exemplary process is as follows:

[0273] At room temperature, dissolve 11 g of CeCl3 in 71 g of water, add 79 g of carrier Y to obtain an 11% CeCl3 / Y catalyst, where carrier Y is a porous metal oxide or microporous molecular sieve other than a porous alumina, and the carrier Y in Examples 68 to 73 is different from each other;

[0274] The remaining settings are the same as those in Example 67. The results of the pyridine conversion rate and the yields of each product are shown in Table 13.

[0275] For easy analysis and comparison, the differences between Examples 68 to 73 are presented in Table 13. It can be found from the data in Table 13 that different chloropyridine product selectivities are shown based on different carriers, allowing for flexible adjustment of the catalyst carrier type as needed to prepare specific types of chloropyridines.

[0276] Example 74

[0277] The only difference between this example and Example 2 is that the reaction raw material chlorine gas is replaced by hydrogen chloride gas. Specifically:

[0278] Step 1: At room temperature, dissolve 3 g of KCl and 20 g of CuCl2 (134.35 g / mol) in 62 g of water, add 77 g of porous alumina, let it stand for 12 hours, then dry it at 80°C - 90°C for 12 hours, and then send it into a muffle furnace and calcine it at 400°C for 5 h to obtain a 3% KCl - 20% CuCl2 / Al2O3 catalyst. Calculated by the metal elements in the active components, the loading amount of the active components of the catalyst is 9.4%;

[0279] The pore volume of the porous alumina is 0.5 mL / g, the particle size distribution is in the range of 3 mm - 8 mm, and the BET specific surface area is 230 m 2 / g;

[0280] Step 2: Weigh 66 g of the above catalyst and load it into a fixed-bed reactor. Feed pyridine into a preheater for vaporization at a flow rate of 0.09 mL / min, and then send the vaporized pyridine into the reactor using N2 as the carrier gas. The flow rate of N2 is 3000 mL / min, and the weight hourly space velocity of pyridine is 0.08 h -1 , and at the same time introduce hydrogen chloride gas to react with pyridine on the catalyst bed. The flow rate of hydrogen chloride is 200 mL / min, and the molar ratio of pyridine to hydrogen chloride is 1:8.82. Continuously introduce air during the reaction to form an oxidizing atmosphere in the reactor. The volume fraction of O2 in this oxidizing atmosphere is 4%, the reaction temperature is 360°C - 430°C, the reaction pressure is maintained at 0.3 MPa, and the reaction duration is 24 h;

[0281] Step 3: After the reaction is completed, wait for the product to cool sufficiently, add ethanol to dissolve it until it is clear and transparent, weigh it, and analyze the composition content by high performance liquid chromatography to calculate the pyridine conversion rate and the yields of each product. The results are shown in Table 14.

[0282] Example 75

[0283] The difference between this example and Example 74 is only that the active component CuCl2 in Step 1 is replaced with an equal amount of CrCl3, and the remaining settings in Step 1 are the same as those in Example 74;

[0284] Except for the above Step 1, the remaining steps and settings are the same as those in Example 74. The results of the pyridine conversion rate and the yields of each product are shown in Table 14.

[0285] Example 76

[0286] The difference between this example and Example 74 is only that the active component CuCl2 in Step 1 is replaced with an equal amount of CeCl3, and the remaining settings in Step 1 are the same as those in Example 74;

[0287] Except for the above step 1, the remaining steps and settings are the same as those in Example 74. The results of pyridine conversion rate and yields of various products are shown in Table 14.

[0288] For easy analysis and comparison, the differences between Example 2 and Examples 74 to 76 are presented in Table 14. It can be seen from Table 14 that using hydrogen chloride gas instead of chlorine gas as the reaction raw material helps to improve the yield of 2,6-dichloropyridine.

[0289] Table 14

[0290]

[0291] In summary, through the various embodiments provided by this application, in an oxidative atmosphere, the chlorination reaction of pyridine and chlorine gas under the action of a catalyst can continuously produce 2,6-dichloropyridine, 2,3,6-trichloropyridine, and 2,3,5,6-tetrachloropyridine while achieving optimized yields. By adjusting the type and loading amount of the active component in the catalyst, the selection of promoters and / or carriers, the reaction atmosphere, etc., the yield of chloropyridine can be significantly increased, and at the same time, the yield of the target product can be flexibly and efficiently increased as needed.

[0292] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same composition and the same effect as the technical idea within the technical solution scope of this application are included in the technical scope of this application. In addition, within the scope of not departing from the main idea of this application, various modifications that those skilled in the art can think of and other ways constructed by combining some components of the embodiments are also included in the scope of this application.

Claims

1. A preparation method of chloropyridine, comprising: under an oxidative atmosphere, subjecting pyridine and a chlorine-containing gas to a chlorination reaction under the action of a catalyst, and the reaction product includes chloropyridine; the catalyst includes an active component and a carrier, and the carrier includes any one or more of porous metal oxides and microporous molecular sieves.

2. The preparation method according to claim 1, characterized in that, The oxidative atmosphere contains oxygen and a protective gas; optionally, the protective gas includes nitrogen, carbon dioxide or an inert gas, and the inert gas includes one or more of helium, neon or argon.

3. The preparation method according to claim 1 or 2, characterized in that, The oxidative atmosphere is formed by introducing air and a protective gas, and the volume fraction of oxygen in the oxidative atmosphere is 2%-10%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The chlorine-containing gas includes chlorine gas and / or hydrogen chloride gas; optionally, the molar ratio of pyridine to chlorine element in the chlorine-containing gas is 1:(6-12).

5. The preparation method according to any one of claims 1 to 4, characterized in that, The weight hourly space velocity of the pyridine is 0.03 h -1 -0.16 h -1 , and it can be optionally 0.07 h -1 -0.10 h -1 .

6. The preparation method according to any one of claims 1 to 5, characterized in that The chloropyridine includes one or more of 2,6-dichloropyridine, 2,3,6-trichloropyridine and 2,3,5,6-tetrachloropyridine.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The porous metal oxide includes one or more of alumina, silica or zirconia, and preferably the porous metal oxide has one or more of the following characteristics: (1) The pore volume of the porous metal oxide is 0.3 mL / g - 1 mL / g; (2) The particle size distribution of the porous metal oxide ranges from 3 mm to 20 mm, and preferably the particle size distribution ranges from 3 mm to 8 mm; (3) The BET specific surface area of the porous metal oxide is 150 m 2 / g - 350 m 2 / g.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The microporous molecular sieve is selected from any one or more of 5A molecular sieve, 13X molecular sieve, NaY molecular sieve, ZSM-5 molecular sieve.

9. The preparation method according to any one of claims 1 to 8, characterized in that, The active component of the catalyst includes transition metal elements and / or rare earth elements. The transition metal elements can be any one or more of copper, cobalt, iron, chromium, tungsten, and the rare earth elements can be any one or more of cerium, lanthanum; preferably, the active component of the catalyst includes any one or more of copper element, chromium element and cerium element.

10. The preparation method according to any one of claims 1 to 9, characterized in that, Calculated by the metal elements in the active component, the loading amount of the active component in the catalyst is 2%-15%, optionally 2%-12%, and further optionally 3%-11%.

11. The preparation method according to any one of claims 1 to 10, characterized in that, The catalyst further includes an auxiliary agent, and the auxiliary agent includes an alkali metal element or an alkaline earth metal element. The alkali metal element can be any one or more of potassium and sodium, and the alkaline earth metal element is selected from any one or more of magnesium, strontium, calcium or barium; preferably, the auxiliary agent includes potassium element and / or magnesium element.

12. The preparation method according to any one of claims 1 to 11, characterized in that, The temperature of the chlorination reaction is 310°C - 430°C, optionally 360°C - 410°C.

13. The preparation method according to any one of claims 1 to 12, characterized in that, The pressure of the chlorination reaction is less than or equal to 1 MPa, preferably less than or equal to 0.5 MPa.

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