A catalyst for synthesizing 3,4-dichlorobenzonitrile and a preparation method thereof

Abstract

The invention discloses a catalyst for synthesizing 3,4-dichlorobenzonitrile and a preparation method thereof, and relates to the technical field of catalysts. Silicon dioxide is used as a carrier, and the active component is composed of the following elements in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is boron or tellurium; N is a rare earth element; Z is selected from at least one of strontium, hafnium and indium; a is in the range of 0.2-0.5; b is in the range of 0.03-0.1; c is in the range of 0.08-0.12; d is in the range of 0.01-0.05; e is in the range of 0.06-0.15; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silicon dioxide in the catalyst is 35-60wt% by weight. The catalyst has good catalytic effect, high yield and high selectivity.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a catalyst for synthesizing 3,4-dichlorobenzonitrile and a preparation method thereof. Background Art

[0002] 3,4-Dichlorobenzonitrile, also known as 3,4-dichlorobenzonitrile, is an important fine chemical and organic synthesis intermediate. It is an important organic raw material for the synthesis of the selective herbicide cyhalofop-butyl; in addition, it can also be widely used as an intermediate for medicines, pigments, dyes, and liquid crystal materials. The traditional preparation method of 3,4-dichlorobenzonitrile is generally prepared using the corresponding aldehyde, aldoxime or acid as raw materials. These methods have high raw material prices, long reaction routes, and serious environmental pollution. 3,4-Dichlorobenzonitrile can also be produced by ammoxidation. The method of preparing 3,4-dichlorobenzonitrile by ammoxidation has the advantages of simple process, continuous operation, simple operation, strong production capacity, significant economic benefits, and environmental friendliness; the core technology of this method is the catalyst.

[0003] At present, the most common and effective catalytic system used for the synthesis of 3,4-dichlorobenzonitrile is the vanadium-based catalyst. Early vanadium-based catalysts generally used the simplest vanadium component or vanadium with other small components. Their overall activity was too high, their selectivity was poor, and their yield was low. From the recent development of the catalyst composition used to synthesize 3,4-dichlorobenzonitrile, there are mainly three compositions: V-Sb, V-Cr and Sb-Fe. These catalysts also have more or less complex preparation processes, harsh preparation conditions, and their economic value needs to be further improved. The high activity of the catalyst is easy to cause deep oxidation, and it has a strong decomposition ability for ammonia, resulting in the generation of a large amount of CO2, CO, H2O and HCN, which requires a large amount of ammonia for the reaction and increases the amount of waste treatment.

[0004] In order to solve the above problems, the Chinese invention patent with the authorization announcement number CN111569925B discloses a special catalyst for preparing 3,4-dichlorobenzonitrile. The carrier of the special catalyst is a silica gel-carbon nitride composite carrier formed by carbon nitride doped silica gel. The composition of the loaded active component is expressed as: VSb b P c D d E e G g O x; wherein D is boron, lanthanum, cerium, samarium, europium, scandium, chromium, molybdenum, bismuth or tungsten; E is titanium, zirconium, manganese, iron, cobalt, nickel, copper, zinc or tin; G is lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium or barium. The invention also discloses the preparation method and use of the catalyst. In the composite carrier of the special catalyst prepared by the invention, carbon nitride acts as a Lewis base and reacts with the active component as a Lewis acid to carry out a Lewis acid-base reaction, thereby strengthening the effect of the active component and the carrier, reducing the loss of the active component, and making the active component more evenly dispersed, thereby improving the strength and wear resistance of the catalyst; extending the service life; carbon nitride can also be used to adjust the catalyst's redox ability and coordination ability with the reactants, thereby improving the activity and selectivity of the catalyst. However, the catalyst composition and preparation process are complex, and the catalytic activity and selectivity still need to be further improved.

[0005] Therefore, it is necessary to seek a more effective method to prepare a catalyst for synthesizing 3,4-dichlorobenzonitrile with good catalytic effect, high yield and high selectivity. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a catalyst for synthesizing 3,4-dichlorobenzonitrile with good catalytic effect, high yield and high selectivity and a preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is boron or tellurium; N is a rare earth element; Z is selected from at least one of strontium, hafnium and indium; a is in the range of 0.2-0.5; b is in the range of 0.03-0.1; c is in the range of 0.08-0.12; d is in the range of 0.01-0.05; e is in the range of 0.06-0.15; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 35-60wt% by weight.

[0008] Preferably, the rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:(1-3):(0.8-1.2).

[0009] Another object of the present invention is to provide a method for preparing the catalyst for synthesizing 3,4-dichlorobenzonitrile, comprising the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source, and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, and then vigorously stirring for 1-2 hours, and then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 195-215° C. for 18-22 hours; taking out the reactor, and washing the reaction system repeatedly with deionized water and anhydrous ethanol after cooling, and then drying it in a vacuum drying oven at 80-90° C. overnight, and finally heating it to 600-800° C. at 4-6° C. / min at room temperature in an inert gas atmosphere, and then keeping it at this temperature for 6-15 hours and then cooling it naturally, grinding it through a 100-300 mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile.

[0010] Preferably, the vanadium source is at least one of vanadium nitrate and vanadium chloride; the antimony source is at least one of antimony nitrate and antimony chloride.

[0011] Preferably, the M source, N source and Z source are soluble salts containing M, N and Z elements respectively.

[0012] Preferably, the M source is tellurium tetrachloride or sodium borate.

[0013] Preferably, the alcohol solvent is ethylene glycol.

[0014] Preferably, the mass ratio of the vanadium source, the alcohol solvent and the sodium acetate is 0.5:(15-25):(3-5).

[0015] Preferably, the inert gas is any one of nitrogen, helium, neon and argon.

[0016] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0017] (1) The preparation method of the catalyst for synthesizing 3,4-dichlorobenzonitrile disclosed in the present invention has abundant raw material sources, simple process route, environmental friendliness, low cost, high yield, and long catalyst life; the preparation efficiency and finished product qualification rate are high, the energy consumption is low, the dependence on equipment is small, and it is suitable for continuous large-scale production, and has good application value.

[0018] (2) The catalyst for synthesizing 3,4-dichlorobenzonitrile disclosed in the present invention uses silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m, wherein: M is boron or tellurium; N is a rare earth element; Z is selected from at least one of strontium, hafnium and indium; a is in the range of 0.2-0.5; b is in the range of 0.03-0.1; c is in the range of 0.08-0.12; d is in the range of 0.01-0.05; e is in the range of 0.06-0.15; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silicon dioxide in the catalyst is 35-60wt% by weight. By reasonably selecting the type and content ratio of each element component in the active component and coordinating with the carrier, the prepared catalyst has good catalytic effect, high yield and high selectivity.

[0019] (3) The catalyst for synthesizing 3,4-dichlorobenzonitrile disclosed in the present invention adopts a hydrothermal reaction and reasonably selects the preparation process parameters, so that the prepared catalyst has a large specific surface area and high catalytic activity. Only a small amount of addition is required to achieve a good catalytic effect. The selectivity and reaction conversion rate for synthesizing 3,4-dichlorobenzonitrile are both high. DETAILED DESCRIPTION

[0020] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0021] Example 1

[0022] A catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is boron; N is a rare earth element; Z is selected from strontium; a is 0.2; b is 0.03; c is 0.08; d is 0.01; e is 0.06; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 35wt% by weight.

[0023] The rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:1:0.8.

[0024] A preparation method of a catalyst for synthesizing 3,4-dichlorobenzonitrile, comprising the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source, and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, and vigorously stirring for 1 hour, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 195°C for 18 hours; taking out the reactor, and repeatedly washing with deionized water and anhydrous ethanol after the reaction system is cooled, and then drying in a vacuum drying oven at 80°C overnight , and finally, the temperature was raised to 600°C at 4°C / min under an inert gas atmosphere at room temperature, and then kept at this temperature for 6 hours and naturally cooled, and ground through a 100-mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile; the vanadium source is vanadium nitrate; the antimony source is antimony nitrate; the M source is sodium borate; the N source is a nitrate of a rare earth element; the Z source is strontium nitrate; the alcohol solvent is ethylene glycol; the mass ratio of the vanadium source, the alcohol solvent, and sodium acetate is 0.5:15:3; and the inert gas is nitrogen.

[0025] Example 2

[0026] A catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is tellurium; N is a rare earth element; Z is hafnium; a is 0.3; b is 0.05; c is 0.09; d is 0.02; e is 0.08; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 45wt% by weight.

[0027] The rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:1.5:0.9.

[0028] A preparation method of a catalyst for synthesizing 3,4-dichlorobenzonitrile comprises the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, stirring vigorously for 1.2 hours, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 200°C for 19 hours; taking out the reactor, and repeatedly washing with deionized water and anhydrous ethanol after the reaction system is cooled, and then drying in a vacuum drying oven at 83°C overnight. Finally, the temperature was raised to 650°C at a rate of 4.5°C / min under an inert gas atmosphere at room temperature, and then kept at this temperature for 8 hours and naturally cooled, and ground through a 150-mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile; the vanadium source is vanadium chloride; the antimony source is antimony chloride; the M source is tellurium tetrachloride; the N source is a chloride salt of a rare earth element; the Z source is hafnium nitrate; the alcohol solvent is ethylene glycol; the mass ratio of the vanadium source, the alcohol solvent, and sodium acetate is 0.5:18:3.5; and the inert gas is helium.

[0029] Example 3

[0030] A catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is boron; N is a rare earth element; Z is indium; a is 0.35; b is 0.06; c is 0.1; d is 0.03; e is 0.1; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 50wt% by weight.

[0031] The rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:2:1.

[0032] A preparation method of a catalyst for synthesizing 3,4-dichlorobenzonitrile, comprising the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, a N source, and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, and vigorously stirring for 1.5 hours, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 205°C for 20 hours; taking out the reactor, and repeatedly washing with deionized water and anhydrous ethanol after the reaction system is cooled, and then drying in a vacuum drying oven at 85°C. night, and finally at room temperature in an inert gas atmosphere, the temperature was raised to 700°C at a rate of 5°C / min, and then kept at this temperature for 12 hours, cooled naturally, and ground through a 200-mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile; the vanadium source is vanadium nitrate; the antimony source is antimony chloride; the M source is sodium borate; the N source is a nitrate of a rare earth element; the Z source is indium nitrate; the alcohol solvent is ethylene glycol; the mass ratio of the vanadium source, the alcohol solvent, and sodium acetate is 0.5:20:4; and the inert gas is neon.

[0033] Example 4

[0034] A catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is a mixture of boron and tellurium in a molar ratio of 3:5; N is a rare earth element; Z is a mixture of strontium, hafnium and indium in a molar ratio of 1:2:1; a is 0.45; b is 0.09; c is 0.11; d is 0.04; e is 0.13; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 55wt% by weight.

[0035] The rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:2.5:1.1.

[0036] A preparation method of a catalyst for synthesizing 3,4-dichlorobenzonitrile, comprising the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source, and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, and vigorously stirring for 1.8 hours, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 212°C for 21 hours; taking out the reactor, and repeatedly washing with deionized water and anhydrous ethanol after the reaction system is cooled, and then drying in a vacuum drying oven at 88°C overnight, and finally heating at room temperature to 750°C at 5.5°C / min in an inert gas atmosphere. ℃, then keep it at this temperature for 14 hours and then cool it naturally, grind it through a 250 mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile; the vanadium source is a mixture of vanadium nitrate and vanadium chloride in a molar ratio of 1:2; the antimony source is a mixture of antimony nitrate and antimony chloride in a molar ratio of 1:3; the N source and the Z source are soluble nitrates containing N and Z elements respectively; the M source is tellurium tetrachloride and sodium borate mixed in a molar ratio of 5:3; the alcohol solvent is ethylene glycol; the mass of the vanadium source, the alcohol solvent and sodium acetate is 0.5:23:4.5; the inert gas is argon.

[0037] Example 5

[0038] A catalyst for synthesizing 3,4-dichlorobenzonitrile, with silicon dioxide as a carrier, and the active component has the following elemental composition in terms of molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is tellurium; N is a rare earth element; Z is hafnium; a is 0.5; b is 0.1; c is 0.12; d is 0.05; e is 0.15; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 60wt% by weight.

[0039] The rare earth element is a mixture of Sc, Y and Pr in a molar ratio of 1:3:1.2.

[0040] A preparation method of a catalyst for synthesizing 3,4-dichlorobenzonitrile comprises the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, stirring vigorously for 2 hours, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 215°C for 22 hours; taking out the reactor, repeatedly washing with deionized water and anhydrous ethanol after the reaction system is cooled, then drying in a vacuum drying oven at 90°C overnight, finally heating to 800°C at 6°C / min under an inert gas atmosphere at room temperature, then keeping the temperature at this temperature for 15 hours, cooling naturally, and grinding through a 300-mesh sieve to obtain a catalyst for synthesizing 3,4-dichlorobenzonitrile; the vanadium source is vanadium nitrate; and the antimony source is antimony chloride. The M source is tellurium tetrachloride; the N source and the Z source are soluble chloride salts containing N and Z elements respectively; the alcohol solvent is ethylene glycol; the mass ratio of the vanadium source, the alcohol solvent and sodium acetate is 0.5:25:5; and the inert gas is argon.

[0041] Comparative Example 1

[0042] A catalyst for synthesizing 3,4-dichlorobenzonitrile and a preparation method thereof are substantially the same as those in Example 1, except that no M source is added.

[0043] Comparative Example 2

[0044] A catalyst for synthesizing 3,4-dichlorobenzonitrile and a preparation method thereof are substantially the same as those in Example 1, except that no Z source is added.

[0045] In order to further illustrate the beneficial technical effects of the catalyst for synthesizing 3,4-dichlorobenzonitrile involved in each embodiment of the present invention, the performance of the catalyst for synthesizing 3,4-dichlorobenzonitrile involved in Examples 1-5 and Comparative Examples 1-2 was evaluated. The evaluation results are shown in Table 1. The evaluation method is as follows: 300 g of the catalyst prepared in each example was added to a steel pipe with an inner diameter of 40 mm, the temperature was raised to 400° C., and the reaction mixture was fed into the reactor at a molar ratio of 3,4-dichlorotoluene: ammonia: oxygen = 1:2.5:6; the reaction pressure was 0.01 MPa, and the space velocity was 800 h -1 , statistics and calculation of 3,4-dichlorotoluene conversion, 3,4-dichlorobenzonitrile selectivity, and 3,4-dichlorobenzonitrile yield.

[0046] Table 1

[0047]

[0048] It can be seen from the data in Table 1 that the catalysts for synthesizing 3,4-dichlorobenzonitrile according to the embodiments of the present invention have better catalytic effects than the comparative products; the combined use of the M source and the Z source is beneficial to improving the above performance.

[0049] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A catalyst for synthesizing 3,4-dichlorobenzonitrile, characterized in that: With silicon dioxide as carrier, the active components are composed of the following elements in molar ratio: V 1.0 Sb a M b Nb c N d Z e O m , wherein: M is boron or tellurium; N is a rare earth element; Z is at least one selected from strontium, hafnium, and indium; a is in the range of 0.2-0.5; b is in the range of 0.03-0.1; c is in the range of 0.08-0.12; d is in the range of 0.01-0.05; e is in the range of 0.06-0.15; m is the number of oxygen atoms required to satisfy the valence of each element in the catalyst; the carrier silica in the catalyst is 35-60wt% by weight; the rare earth element is a mixture of Sc, Y, and Pr in a molar ratio of 1:(1-3):(0.8-1.2); The preparation method of the catalyst for synthesizing 3,4-dichlorobenzonitrile comprises the following steps: dispersing a vanadium source, an antimony source, an M source, a niobium source, an N source and a Z source in an alcohol solvent, stirring evenly, slowly adding sodium acetate and silica sol, stirring vigorously for 1-2 hours, then transferring the mixture to a hydrothermal reactor lined with polytetrafluoroethylene, and reacting at 195-215°C for 18-22 hours; taking out the reactor, washing repeatedly with deionized water and anhydrous ethanol after the reaction system is cooled, then drying overnight in a vacuum drying oven at 80-90°C, finally heating to 600-800°C at 4-6°C / min in an inert gas atmosphere at room temperature, then keeping the temperature at this temperature for 6-15 hours, cooling naturally, and grinding through a 100-300 mesh sieve to obtain the catalyst for synthesizing 3,4-dichlorobenzonitrile.

2. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that The vanadium source is at least one of vanadium nitrate and vanadium chloride; the antimony source is at least one of antimony nitrate and antimony chloride.

3. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that The M source, N source and Z source are soluble salts containing M, N and Z elements respectively.

4. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that The M source is tellurium tetrachloride or sodium borate.

5. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that: The alcohol solvent is ethylene glycol.

6. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that: The mass ratio of the vanadium source, the alcohol solvent and the sodium acetate is 0.5:(15-25):(3-5).

7. The catalyst for synthesizing 3,4-dichlorobenzonitrile according to claim 1, characterized in that: The inert gas is any one of nitrogen, helium, neon and argon.

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