A catalyst and its preparation method and application

Abstract

The present invention discloses a catalyst and a preparation method and application thereof, belonging to the field of chemical technology. The catalyst comprises a carrier and an active component; the active component is metallic nickel, the carrier is silicon dioxide, and the nickel is loaded on the surface of the silicon dioxide; wherein the specific surface area of ​​the silicon dioxide is 7 to 12 m 2 / g, and the total pore volume is 0.005~0.035 m 3 / g. The self-made silica carrier of the present invention has the characteristics of small specific surface area and small pore volume, thereby effectively preventing the reactant from further staying on the catalyst after being converted into hydroxylamine and continuing to hydrogenate to form aniline, having a good inhibitory effect on the hydrogenation depth, and having a great advantage in the reaction selectivity of nitro hydrogenation to synthesize hydroxylamine, the raw material conversion rate reaches 100%, the product selectivity reaches 98.5% to 99%, and the catalyst can be continuously produced on a fixed bed by simple tableting.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and in particular to a catalyst and a preparation method and application thereof. Background Art

[0002] Pyraclostrobin is a broad-spectrum methoxyacrylate fungicide with a pyrazole structure discovered by BASF in Germany in 1993. The fungicide has a broad fungicide spectrum, high efficiency, low toxicity, non-target biosafety and environmental friendliness, and is widely used. N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine is an important intermediate in the comprehensive route of pyraclostrobin and the key to the synthesis of pyraclostrobin. However, the traditional preparation method of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine often adopts batch reactor reaction, which is often accompanied by the production of by-products and is easily over-reduced to aniline compounds. Therefore, the requirements for the catalyst are relatively harsh and the requirements for the reaction process are very high.

[0003] The prior art discloses a method for synthesizing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]phenylhydroxylamine: the metal Pt is loaded on the ZSM-5 molecular sieve by an impregnation method, and the batch kettle is charged after drying at 110°C to 130°C. By using the metal-loaded molecular sieve as a catalyst, the N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]phenylhydroxylamine content of the final product reaches more than 97.0%, the yield reaches more than 95.0%, and the main by-products are less than 0.1%.

[0004] The prior art also discloses a method for preparing N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl)phenyl]hydroxylamine: 2-[(N-4-chlorophenyl)-1H-pyrazol-3-oxymethyl]nitrobenzene is used as a raw material, and a cobalt salt (any one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate or a hydrate of these four cobalt salts) is used as a catalyst. Taking cobalt sulfate as an example, the raw material conversion rate is 100% and the product selectivity is 94.5%.

[0005] The prior art also discloses a synthesis process of pyraclostrobin: based on the structure of 2-nitrobenzyl bromide to generate 1-(4-chlorophenyl)-3-[2-(nitrophenyl)methoxy]-1H-pyrazole, ammonium chloride and water are added to a reaction bottle, hydrolyzed at room temperature, and Zn powder is used to reduce the nitro group to hydroxylamine, with a yield of 90-94%.

[0006] The prior art also discloses that 2-[(N-4-chlorophenyl)-1H-pyrazole-3-oxymethyl]nitrobenzene is used as a raw material, 5% of a Pt / C catalyst is added to an autoclave, the reaction temperature is 18-20°C, the reaction time is 10 hours, the yield is 92.6%, and the purity is 97.6%.

[0007] In the above-mentioned various synthesis processes of pyraclostrobin, the synthesis of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazol-3-oxymethyl]hydroxylamine is the key to the whole process, and the reduction of the nitro raw material to hydroxylamine is also a difficult point. There are many kinds of catalysts for preparing hydroxylamine by hydrogenation of nitro, but there are several problems: 1. Precious metals are the main active components and are expensive; 2. The hydrogenation depth of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene is difficult to control; 3. Cobalt-based and zinc-based catalysts are mostly used for batch kettle hydrogenation reactions and do not have continuous operation conditions. Summary of the invention

[0008] The main purpose of the present invention is to provide a catalyst and a preparation method and application thereof, so as to solve the problems in the prior art of preparing hydroxylamine by nitro hydrogenation that the hydrogenation depth is difficult to control, resulting in low yield, unstable yield, expensive precious metals of the catalyst and unsuitability for continuous operation.

[0009] In order to achieve the above object, according to one aspect of the present invention, a catalyst is provided, comprising a carrier and an active component; the active component is metallic nickel, the carrier is silicon dioxide, and the metallic nickel is loaded on the surface of the silicon dioxide;

[0010] Among them, the specific surface area of ​​silicon dioxide is 7~12 m 2 / g; the total pore volume of silica is 0.005~0.035 m 3 / g.

[0011] Furthermore, the loading amount of metallic nickel in the silica carrier is 20-30%.

[0012] Furthermore, the pore size of silica is 9-15 nm.

[0013] According to a second aspect of the present invention, there is provided a method for preparing the above catalyst, comprising the following steps:

[0014] Step S1: mixing an alkaline substance, an organic solvent, water, a template and a silicon source to form a first mixture;

[0015] Wherein, the template agent is polyethylene oxide;

[0016] Step S2: the first mixture is allowed to stand, purified, dried, and calcined to obtain silicon dioxide;

[0017] Step S3: mixing silicon dioxide, water and a nickel source under ultrasound and allowing to stand to obtain a second mixture;

[0018] Step S4: The second mixture is purified, dried, and calcined in an inert atmosphere to obtain a catalyst.

[0019] Furthermore, the molar ratio of the alkaline substance, the organic solvent, the silicon source and water is (0.1-0.3):1:0.4:1.

[0020] Furthermore, the alkaline substance includes aqueous ammonia.

[0021] Furthermore, the mass of polyethylene oxide is 2% to 3% of the theoretically calculated mass of silicon dioxide.

[0022] Furthermore, the molar ratio of nickel source: water: silicon dioxide is (0.034~0.051):1:(0.117~0.133).

[0023] Further, the silicon source is selected from ethyl orthosilicate and / or tetrabutyl silicate.

[0024] Further, the nickel source is selected from nickel nitrate and / or nickel chloride.

[0025] Furthermore, the organic solvent is ethanol.

[0026] Further, in step S2, the standing time of the first mixture is 3 to 4 hours, the purification includes filtering and washing; the washing includes alternating washing with purified water and ethanol until the pH is 7; the drying temperature is 90°C to 100°C; the roasting temperature is 500°C to 650°C, and the roasting time is 5 to 6 hours.

[0027] Further, in step S3, silicon dioxide and water are mixed to form a mixed system A, a nickel source and water are mixed to form a system B, B is added dropwise to A in an ultrasonic field, aged for 20 to 30 minutes, and allowed to stand for 2 to 3 hours. The dropping time is 20 to 30 minutes, and the ultrasonic output power is 60 to 70 W.

[0028] Furthermore, in step S4, the second mixture is washed with pure water and ethanol, the drying temperature is 90-100°C, and the drying time is 12-24 hours; the inert atmosphere is nitrogen or argon atmosphere; the calcination temperature is 300-400°C, the calcination time is 5-6 hours, and the calcination heating rate is 5-15°C / min.

[0029] According to a third aspect of the present invention, there is provided a method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine, comprising: contacting and reacting raw materials 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene, hydrogen and a catalyst to obtain N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine; wherein the catalyst is the above catalyst or the catalyst prepared by the above method.

[0030] Furthermore, the feed rate of hydrogen is 200-220 mL / min.

[0031] Further, the solution of 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene is mixed with hydrogen, the molar concentration of the solution of 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene is 0.1-0.2 M, and the feed rate is 10-30 g / min.

[0032] Furthermore, the solution of 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene is an ethanol solution thereof.

[0033] Furthermore, the amount of the catalyst used is 350-450 g.

[0034] Furthermore, the reaction temperature is 0~5°C, and the reaction pressure is 0.5~1.0MPa.

[0035] Furthermore, the reaction is carried out in a continuous fixed bed reactor.

[0036] According to a fourth aspect of the present invention, a method for preparing pyraclostrobin is provided, which comprises an intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine; the intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine comprises the N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine prepared by the above method.

[0037] According to a fifth aspect of the present invention, there is provided use of the above catalyst or the catalyst prepared by the above method in preparing hydroxylamine by nitro hydrogenation or in preparing pyraclostrobin.

[0038] By applying the technical scheme of the present invention, a metal catalyst with inexpensive nickel as an active component is synthesized, and the active component nickel is introduced into a self-made silica carrier by an ultrasonic impregnation method. Due to the characteristics of the self-made silica carrier having a small specific surface area and a small pore volume, the reactant is effectively prevented from further staying on the catalyst after being converted into hydroxylamine and continuing to be hydrogenated to form aniline, and has a good inhibitory effect on the hydrogenation depth, and has a great advantage in the reaction selectivity of nitro hydrogenation to synthesize hydroxylamine. The raw material conversion rate reaches 100%, and the product selectivity reaches 98.5% to 99%. Moreover, the catalyst can be continuously produced on a fixed bed by simple tableting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] Figure 1 The liquid phase detection spectrum of the system after the fixed bed reaction of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine prepared in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] As mentioned in the background art, the preparation method of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine adopts a batch reactor reaction, which is often accompanied by the production of by-products, and is easily over-reduced to aniline compounds, so the requirements on the catalyst are relatively stringent, and the requirements on the reaction process are very high; for this reason, the present invention has developed a catalyst that can inhibit the excessive reduction of raw materials to aniline compounds to a certain extent to increase the production of the target product hydroxylamine.

[0043] The catalyst of the present invention comprises a carrier and an active component;

[0044] The active component is metallic nickel, the carrier is silicon dioxide, and the nickel is loaded on the surface of silicon dioxide;

[0045] Among them, the specific surface area of ​​silicon dioxide is 7~12 m 2 / g, and the total pore volume is 0.005~0.035 m 3 / g.

[0046] The catalyst carrier of the invention has the characteristics of small specific surface area and small pore volume, and the nickel atoms of the active component are mainly concentrated on the surface of the carrier silicon dioxide, and the active component basically does not enter the interior of the carrier, forming a catalyst molecule with a core-shell structure. When used in the reaction of preparing hydroxylamine from nitro, the generated hydroxylamine is quickly released from the surface of the carrier, and the characteristic of the catalyst carrier without internal pores can effectively prevent the reactants from further staying on the surface of the carrier and continuing to hydrogenate to form aniline, which has a good inhibitory effect on the hydrogenation depth and has great advantages in the reaction of hydroxylamine synthesis.

[0047] As a specific implementation method, the loading amount of metallic nickel on the silica carrier (the mass percentage of nickel on silica) is 20-30%. This content can fully exert the catalytic effect of the active component nickel.

[0048] The pore size of the silica carrier is 9-15 nm, but the pore volume and specific surface area are small.

[0049] The present invention also provides a method for preparing the above catalyst, comprising the following steps:

[0050] Step S1: mixing an alkaline substance, an organic solvent, water, a template and a silicon source to form a first mixture;

[0051] Wherein, the template agent is polyethylene oxide;

[0052] Step S2: the first mixture is allowed to stand, purified, dried, and calcined to obtain silicon dioxide;

[0053] Step S3: mixing silicon dioxide, water and a nickel source under ultrasound and allowing to stand to obtain a second mixture;

[0054] Step S4: The second mixture is purified, dried, and calcined in an inert atmosphere to obtain a catalyst.

[0055] The present invention firstly selects polyethylene oxide (PEO) as a template for synthesizing silicon dioxide. After a silicon source is quickly added, the mutual repulsion between the polyethylene oxide (PEO) micelle as a neutral template and the silicon source is very weak. The silicon source is rapidly hydrolyzed with the template as a structure-directing agent to form a condensation polymer. The condensation polymer forms a micelle-solution polymerization silicon source precursor with a small specific surface area and almost no pore volume through its own self-assembly function.

[0056] The present invention loads the nickel source on the self-made silica by ultrasonic loading method, and the nickel atoms are mainly concentrated on the surface of the carrier silica, and the active components basically do not enter the interior of the carrier, forming a catalyst molecule similar to a core-shell structure. When the reactants and hydrogen are in contact with the catalyst, the hydroxylamine formed by hydrogenation is quickly released from its surface, and the catalyst has no internal pores, which effectively prevents the reactants from further staying and continuing to hydrogenate to form aniline, and has a good inhibitory effect on its hydrogenation depth.

[0057] The invention has simple process and low cost from the preparation of silicon dioxide to the loading of cheap active components. The introduction of ultrasonic impregnation method in the synthesis process greatly saves the synthesis time of the catalyst, and the catalyst can be continuously produced on a fixed bed through simple tableting. The selectivity of hydroxylamine obtained by the reaction is extremely high, which has positive significance for industrial scale-up.

[0058] As a specific implementation method, the molar ratio of the alkaline substance, the organic solvent, the silicon source and water is (0.1-0.3):1:0.4:1; preferably, the alkaline substance is often ammonia water, which is used to precipitate the silicon source to prepare silicon dioxide.

[0059] In the present invention, silicon dioxide is synthesized from a silicon source, and the alkaline substances, organic solvents and water in the raw materials are filtered out or evaporated by roasting during the synthesis process. Therefore, the theoretical mass of silicon dioxide can be calculated from the mass of the silicon source.

[0060] In order to obtain a silica carrier with a smaller specific surface area and pore volume and successfully prepare the carrier, the mass of polyethylene oxide is 2% to 3% of the theoretically calculated mass of silica.

[0061] In order to make the catalyst have better catalytic activity, the molar ratio of nickel source: water: silicon dioxide is (0.034~0.051):1:(0.117~0.133).

[0062] As a specific implementation, the silicon source is selected from ethyl orthosilicate and / or tetrabutyl silicate.

[0063] As a specific embodiment, the nickel source is selected from nickel nitrate and / or nickel chloride.

[0064] As a specific implementation manner, the organic solvent is ethanol.

[0065] In order to obtain a material with a smaller specific surface area and a smaller pore volume, specifically in step S2, the first mixture is stirred for 0.5 to 1 h, and is allowed to stand for 3 to 4 h. Purification includes filtering and washing; washing includes alternating washing with purified water and ethanol until the pH is 7; the drying temperature is 90 to 100°C; the calcination temperature is 500°C to 650°C, and the calcination time is 5 to 6 h.

[0066] As a preferred embodiment, in step S3, silicon dioxide and water are mixed to form a mixed system A, a nickel source and water are mixed to form a system B, B is added dropwise to A in an ultrasonic field, aged for 20 to 30 minutes, and allowed to stand for 2 to 3 hours. The dropping time is 20 to 30 minutes, and the ultrasonic output power is 60 to 70 W.

[0067] As a preferred embodiment, in step S4, the second mixture is washed with pure water and ethanol, the drying temperature is 90-100°C, and the drying time is 12-24 hours; the inert atmosphere is nitrogen or argon atmosphere; the calcination temperature is 300-400°C, the calcination time is 5-6 hours, and the calcination heating rate is 5-15°C / min.

[0068] The catalyst prepared by the present invention has a small specific surface area and pore volume, and can be used in the reaction of hydrogenating nitrobenzene to prepare hydroxylamine. Therefore, the present invention also provides a method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine, comprising: contacting and reacting raw materials 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene, hydrogen and a catalyst to obtain N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine; wherein the catalyst is the above catalyst or a catalyst prepared by the above method.

[0069] In order to obtain better reaction effects of hydrogenating nitrobenzene compounds to prepare hydroxylamine compounds, such as improving conversion rate and yield, in the method of the present invention, the feed rate of hydrogen is 200-220 mL / min; 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene is prepared by mixing a solution of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene with hydrogen, the molar concentration of the solution of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene is 0.1-0.2 M, and the feed rate of the solution of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene is 10-30 g / min; the amount of the catalyst used is 350-450 g, preferably 400 g.

[0070] The solution of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene may be an organic solution thereof, such as a methanol solution or an ethanol solution of nitrobenzene.

[0071] The present invention adds the catalyst into a continuous fixed bed reactor, and reduces the temperature for 1 to 4 hours under the condition of heating to 300 to 350° C. at a heating rate of 5° C. / min in a hydrogen atmosphere, then cools the temperature to a reaction temperature of 0 to 5° C., feeds 20 g / min of a 0.1 M 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene ethanol solution and 200 to 220 mL / min of hydrogen, and uses a liquid phase test reaction.

[0072] When the catalyst of the present invention is used in the hydrogenation reaction, the conversion rate of the raw material 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene reaches 100%, and the selectivity of the product N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazol-3-oxymethyl]hydroxylamine reaches 98.5% to 99%, and the reaction effect is excellent.

[0073] Since N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine is an important intermediate product for preparing pyraclostrobin, the hydroxylamine compound prepared by the method of the present invention can be used to produce pyraclostrobin. Therefore, the present invention provides a method for preparing pyraclostrobin, which includes an intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine; the intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine includes the N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine prepared by the method.

[0074] Therefore, the catalyst and the hydroxylamine compound prepared by the present invention can be used in the production of pyraclostrobin.

[0075] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0076] Example 1 (Preparation of Catalyst)

[0077] (1) Weigh 650 g of ammonia water, 1150 g of ethanol, 450 g of purified water, and 12 g of polyethylene oxide (PEO) respectively into a beaker, and add 2083 g of tetraethyl orthosilicate dropwise while stirring. After the addition is complete, continue stirring for 0.5 h, let stand for 3 h, filter, wash alternately with purified water and ethanol until pH = 7, dry at 100 ° C, and calcine at 650 ° C for 5 h to obtain a silica carrier;

[0078] (2) 600 g of silicon dioxide and 800 mL of purified water were placed in a beaker to obtain a mixed system A, and 595 g of nickel nitrate was dissolved in 400 g of purified water to obtain a mixed system B. B was added dropwise to A in an ultrasonic field for 30 min at an ultrasonic output power of 60 W.

[0079] (3) Aging under ultrasound for 20 minutes and standing for 2 hours;

[0080] (4) The mixed liquid system was filtered, washed with purified water until neutral, and then rinsed once with ethanol, dried at 90°C for 24 hours, and the dried solid was calcined at 300°C with a heating rate of 8°C / min under the protection of inert gas nitrogen for 6 hours to obtain a solid catalyst. The specific surface area, pore volume and pore size of the catalyst were measured by the BET method. The results are shown in Table 1.

[0081] Example 2 (Preparation of Catalyst)

[0082] (1) Weigh 700 g of ammonia water, 1150 g of ethanol, 450 g of purified water, and 18 g of polyethylene oxide (PEO) respectively into a beaker, add 3205 g of tetrabutyl silicate dropwise while stirring, continue stirring for 1 hour after the addition is complete, let stand for 4 hours, filter, wash alternately with purified water and ethanol until the pH value is 7, dry at 100° C., and calcine at 500° C. for 6 hours to obtain a silica carrier;

[0083] (2) 600 g of silicon dioxide and 800 mL of purified water were placed in a beaker to obtain a mixed system A, and 331 g of nickel chloride and 347 g of purified water were dissolved in a mixed system B. B was added dropwise to A in an ultrasonic field. The addition time was 25 min and the ultrasonic output power was 70 W.

[0084] (3) Aging under ultrasound for 30 minutes and standing for 3 hours;

[0085] (4) The mixed liquid system was filtered, washed with purified water until neutral, and then rinsed once with ethanol. The mixture was dried at 100°C for 12 h. The dried solid was calcined at 400°C with a heating rate of 15°C / min under the protection of inert gas argon for 5 h to obtain a solid catalyst. The specific surface area, pore volume and pore size of the catalyst were measured by the BET method. The results are shown in Table 1.

[0086] Example 3 (Preparation of Catalyst)

[0087] (1) Weigh 800 g of ammonia water, 1150 g of ethanol, 450 g of purified water, and 15 g of polyethylene oxide (PEO) respectively into a beaker, add 3205 g of tetrabutyl silicate dropwise while stirring, continue stirring for 1 hour after the addition is complete, let stand for 4 hours, filter, wash alternately with purified water and ethanol until the pH value is 7, dry at 100° C., and calcine at 500° C. for 6 hours to obtain a silica carrier;

[0088] (2) 600 g of silicon dioxide and 800 mL of purified water were placed in a beaker to obtain a mixed system A, and 331 g of nickel chloride and 394 g of purified water were dissolved in a mixed system B. B was added dropwise to A in an ultrasonic field for 20 min at an ultrasonic output power of 70 W.

[0089] (3) Aging under ultrasound for 30 minutes and standing for 3 hours;

[0090] (4) The mixed liquid system was filtered, washed with purified water until neutral, and then rinsed once with ethanol, dried at 100°C for 12 h, and the dried solid was calcined at 350°C with a heating rate of 10°C / min under the protection of inert gas argon for 5.5 h to obtain a solid catalyst. The BET method was used to detect the specific surface area, pore volume and pore size of the catalyst. The results are shown in Table 1.

[0091] Example 4 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0092] (1) The solid prepared in Example 1 was used as a catalyst, and after tableting, it was filled into a continuous fixed bed reactor, and reduced at 350° C. under a 5% hydrogen atmosphere for 1 h, and then cooled to 0° C., and the raw materials were passed through to perform a performance test;

[0093] (2) Under the conditions of reaction temperature of 0°C and 0.5 MPa, 20 g / min of 0.1 M 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene ethanol solution and 200 mL / min of hydrogen were fed to contact with 400 g of catalyst for hydrogenation reaction to obtain product 1. The components of product 1 were analyzed. The selectivity of hydroxylamine compounds in product 1 and the conversion rate of raw materials were obtained by liquid phase analysis, as shown in Table 1.

[0094] Example 5 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0095] (1) The solid prepared in Example 2 was formed into tablets, loaded into a continuous fixed bed reactor as a catalyst, and reduced at 300° C. for 2 h under a 5% hydrogen atmosphere, then cooled to 5° C. and the raw materials were passed through for performance testing;

[0096] (2) Under the conditions of reaction temperature of 5°C and 1 MPa, 20 g / min of 0.2 M 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene ethanol solution and 220 mL / min of hydrogen were fed to contact with 400 g of catalyst and a hydrogenation reaction occurred to obtain product 2. The components of product 2 were analyzed. The selectivity of hydroxylamine compounds in product 2 and the conversion rate of raw materials were obtained by liquid phase analysis, as shown in Table 1.

[0097] Example 6 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0098] (1) The solid prepared in Example 3 was formed into tablets and loaded into a continuous fixed bed reactor as a catalyst. The temperature was raised to 325° C. for 1.5 h under a 5% hydrogen atmosphere, and then the temperature was lowered to 2° C. The raw materials were passed through to conduct a performance test.

[0099] (2) Under the conditions of reaction temperature of 5°C and 0.85 MPa, 20 g / min of 0.1 M 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene ethanol solution and 220 mL / min of hydrogen were fed to contact with 400 g of catalyst and a hydrogenation reaction occurred to obtain product 3. The component analysis of product 3 was performed. The selectivity of hydroxylamine compounds in product 3 and the conversion rate of raw materials were obtained by liquid phase analysis, as shown in Table 1 and Figure 1 shown. Figure 1 This is a liquid chromatogram of the effluent after the catalytic hydrogenation in Example 6; Figure 1 The retention time of 7.156 min corresponds to the peak position of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazol-3-oxymethyl]hydroxylamine; the raw material 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene has not eluted and has been completely converted.

[0100] Comparative Example 1 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0101] (1) 600 g of commercial silicon dioxide and 800 mL of purified water were placed in a beaker to obtain a mixed system A, and 331 g of nickel chloride was dissolved in 222 g of purified water to obtain a mixed system B. B was added dropwise to A in an ultrasonic field. The addition time was 25 min and the ultrasonic output power was 70 W.

[0102] (2) Aging under ultrasound for 30 minutes and standing for 3 hours;

[0103] (3) After filtering the mixed liquid system, the system was washed with purified water until neutral and then rinsed once with ethanol, dried at 100°C for 12 h, and the dried solid was calcined at 400°C for 5 h at a heating rate of 15°C / min under the protection of inert gas argon. The specific surface area, pore volume and average pore size of the solid product were measured by the BET method. The results are shown in Table 1.

[0104] (4) After the calcined solid is formed into tablets, it is loaded into a fixed bed as a catalyst, reduced at 300°C for 2 hours under a 5% hydrogen atmosphere, then cooled to 5°C and the raw materials are passed through for performance testing;

[0105] (5) The reaction temperature was 5°C, 20 g / min of 0.1 M 2-[(N-(p-chlorophenyl)-3-pyrazolyloxymethyl)-nitrobenzene ethanol solution, 210-220 mL / min of hydrogen feed, and 400 g of catalyst were contacted to obtain product 4. The selectivity and conversion rate of the target product hydroxylamine compound in the product were detected. The results are shown in Table 1.

[0106] Comparative Example 2 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0107] 0.075 g of metal Pt was loaded on 7.43 g of ZSM-5 molecular sieve by impregnation method, and then dried at 120°C for batch kettle feeding; 100 g of 2-[(N-p-chlorophenyl)-3-pyrazoloxymethyl]nitrobenzene, 400 g of dichloroethane, 7.5 g of catalyst and 50 g of hydrazine hydrate were reacted at 40°C for 2 h to obtain a product. The yield of the target product in the product was detected, and the results are shown in Table 1.

[0108] Comparative Example 3 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0109] 3.30 g of raw material 2-[(N-4-chlorophenyl)-1H-pyrazole-3-oxymethyl]nitrobenzene and 0.20 g of catalyst cobalt sulfate were added, ethanol solvent and hydrazine hydrate were added, and the reaction was carried out at a temperature of 20°C for 1 hour. After the reaction was completed, liquid chromatography was performed. The results are shown in Table 1.

[0110] Comparative Example 4 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0111] On the basis of 32.95 g of 2-nitrobenzyl bromide to generate 1-(4-chlorophenyl)-3-[2-(nitrophenyl)methoxy]-1H-pyrazole, 60 ml of ethanol and 9.75 g of zinc powder were added, and 10.2 g of ammonium chloride and 150 ml of aqueous solution were added dropwise at 45°C. After the reaction, the mixture was cooled to room temperature, and a white solid was obtained after washing, extraction, drying and concentration. The product yield is shown in Table 1.

[0112] Comparative Example 5 (Preparation of N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine)

[0113] Using 2-[(N-4-chlorophenyl)-1H-pyrazole-3-oxymethyl]nitrobenzene as raw material, 5% Pt / C catalyst was added into the autoclave, the reaction temperature was 18-20°C, the reaction time was 10h, the yield was 92.6%, and the purity was 97.6%.

[0114] Table 1 is a table showing the BET data of the nickel silicon catalyst of the embodiment and the reaction results of the comparative example.

[0115] Table 1 BET data and reaction performance

[0116]

[0117] From the results in Table 1, it can be seen that the BET specific surface areas of the nickel silicon catalysts prepared in Examples 1 to 3 of the present invention are in the range of 7.78 to 11.87 m2 / g, and the total pore volume is between 0.008 and 0.03 cm 3 / g; when the catalyst is used in the preparation of hydroxylamine from nitrobenzene, the raw material conversion rate is all 100%, the target product selectivity reaches 98.5%~99%, and the catalytic effect is very good.

[0118] In Comparative Example 1, a nickel silicon catalyst is obtained under the same preparation conditions, but its silicon dioxide is a commercial product with a specific surface area of ​​237.2 and a total pore volume of 0.842. When the catalyst is used in the preparation of hydroxylamine from nitrobenzene, although the raw material conversion rate reaches 100%, the selectivity of the target product hydroxylamine is only 79%, that is, the content of by-products in the hydrogenation catalytic reaction is relatively high. Under the same reaction conditions, only the pore structure of the silicon dioxide is different, and the catalytic effect is very different, indicating that the reactants in Comparative Example 1 will further stay in the large pore volume of the silicon dioxide carrier after becoming hydroxylamine on the catalyst to continue hydrogenation to form aniline. The catalyst has no good inhibitory effect on the depth of hydrogenation, so that the yield of the target product hydroxylamine compounds is low.

[0119] The comparison also shows that when the small specific surface area (only 1 / 20 of that in comparative example 1) and small pore volume (close to 1 / 100) prepared by the present invention is used in the reaction of nitro to hydroxylamine, the generated hydroxylamine is quickly released from the surface of the carrier. The characteristic of the catalyst carrier without internal pores can effectively prevent the reactants from further staying on the surface of the carrier and continuing to hydrogenate to form aniline, which has a good inhibitory effect on the depth of hydrogenation and has great advantages in the reaction of hydroxylamine synthesis.

[0120] The active component of the catalyst in Comparative Example 2 is platinum, which is a precious metal with high cost and is only suitable for batch feeding (intermittent). Due to the raw material properties of the catalyst itself, it cannot be used in a continuous fixed bed reactor, and the raw material conversion rate in this method is relatively low, and the product hydroxylamine product selectivity is 95%, which is lower than the yield of the present invention. The present invention adopts a newly developed catalyst and a nickel active component, which not only reduces the catalyst cost, but also further improves the product yield. Moreover, the nickel silicon catalyst can be used in a continuous fixed bed reactor to achieve the purpose of continuous production and improve production efficiency.

[0121] The catalyst of Comparative Example 3 is cobalt, and the raw material conversion rate is only 60%, which is significantly lower than that of the present invention.

[0122] The catalyst of Comparative Example 4 is zinc powder, and the selectivity of hydroxylamine is 95.1%, which is significantly lower than that of the present invention.

[0123] The catalyst of Comparative Example 5 is a platinum-carbon composite material containing precious metals, and the hydroxylamine yield is 92.6%, and the raw material conversion rate is 97.6%, which are significantly lower than those of the present invention. It is a platinum-carbon material catalyst and is not suitable for a continuous fixed bed reactor, and has a low production efficiency.

[0124] Through the above comparison, it can be seen that the present invention synthesizes a metal catalyst with inexpensive nickel as an active component, and introduces the active component nickel into a homemade silica carrier by ultrasonic impregnation. Due to the characteristics of small specific surface area and small pore volume of the homemade silica carrier, the reactant is effectively prevented from further staying on the catalyst after becoming hydroxylamine and continuing to hydrogenate to form aniline, which has a good inhibitory effect on the hydrogenation depth and has a great advantage in the reaction selectivity of nitro hydrogenation to synthesize hydroxylamine. The raw material conversion rate reaches 100%, and the product selectivity reaches 98.5%~99%. Moreover, the catalyst (characteristics of nickel silicon material) can be continuously produced on a fixed bed by simple tableting.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine, characterized in that: The preparation method comprises: contacting and reacting the raw material 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene, hydrogen and a catalyst to obtain the N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazol-3-oxymethyl]hydroxylamine; The catalyst comprises a carrier and an active component; the active component is metallic nickel, the carrier is silicon dioxide, and the metallic nickel is loaded on the surface of the silicon dioxide; the specific surface area of ​​the silicon dioxide is 7 to 12 m 2 / g; the total pore volume of the silica is 0.005~0.035 m 3 / g; The preparation method of the catalyst comprises the following steps: Step S1: mixing an alkaline substance, an organic solvent, water, a template and a silicon source to form a first mixture; Wherein, the template agent is polyethylene oxide; Step S2: the first mixture is allowed to stand, purified, dried, and calcined to obtain silicon dioxide; Step S3: mixing the silicon dioxide, water and nickel source under ultrasonic conditions and allowing to stand to obtain a second mixture; Step S4: the second mixture is purified, dried, and calcined in an inert atmosphere to obtain the catalyst; The molar ratio of the alkaline substance, the organic solvent, the silicon source and the water is (0.1-0.3):1:0.4:1; The mass of the polyethylene oxide is 2% to 3% of the theoretically calculated mass of silicon dioxide; The molar ratio of the nickel source, the water, and the silicon dioxide is (0.034-0.051):1:(0.117-0.133).

2. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The loading amount of the metal nickel on the silica is 20-30%; and / or the pore size of the silica is 9-15 nm.

3. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The silicon source is selected from ethyl orthosilicate and / or tetrabutyl silicate; and / or, the nickel source is selected from nickel nitrate and / or nickel chloride; and / or, the organic solvent is ethanol.

4. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: In step S2, the first mixture is allowed to stand for 3 to 4 hours, the purification includes filtering and washing, the washing includes washing with purified water and ethanol alternately until the pH is 7; the drying temperature is 90°C to 100°C; the roasting temperature is 500°C to 650°C, and the roasting time is 5 to 6 hours; And / or, in step S3, silicon dioxide and water are mixed to form a mixed system A, a nickel source and water are mixed to form a system B, and the B is added dropwise to the A in an ultrasonic field, aged for 20 to 30 minutes, and allowed to stand for 2 to 3 hours. The dropping time is 20 to 30 minutes, and the ultrasonic output power is 60 to 70 W.

5. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: In step S4, the second mixture is washed with pure water and ethanol, the drying temperature is 90-100°C, and the drying time is 12-24 hours; the inert atmosphere is nitrogen or argon atmosphere; the calcination temperature is 300-400°C, the calcination time is 5-6 hours, and the calcination heating rate is 5-15°C / min.

6. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The feed rate of hydrogen is 200-220 mL / min.

7. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene solution is mixed with hydrogen, the molar concentration of the 2-[(N-p-chlorophenyl)-3-pyrazolyloxymethyl]nitrobenzene solution is 0.1-0.2 M, and the feed rate is 10-30 g / min.

8. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The amount of the catalyst used is 350-450 g.

9. The method for preparing N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine according to claim 1, characterized in that: The reaction temperature is 0-5°C, and the reaction pressure is 0.5-1.0MPa; And / or, the reaction is carried out in a continuous fixed bed reactor.

10. A method for preparing pyraclostrobin, comprising the intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine; characterized in that: The intermediate N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine includes the N-hydroxy-N-2-[N-(p-chlorophenyl)pyrazole-3-oxymethyl]hydroxylamine prepared by the method according to any one of claims 1 to 9.

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