Preparation method of o-nitroanisole

Abstract

The invention discloses a synthesis method of o-nitroanisole, which comprises the following step: under the action of a catalyst, catalyzing o-nitrophenol and methanol to generate the o-nitroanisole. Wherein the catalyst is a composite catalyst of silver type loaded by SBA-15 and platinum type loaded by niobium carbide multilayer nanosheets. The conversion rate of o-nitrophenol can reach 75% or above, the selectivity of o-nitroanisole is 98% or above, and continuous and stable operation can be carried out for 3000 h or above.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a method for preparing o-nitroanisole by reacting o-nitrophenol with methanol. Background Art

[0002] o-Nitroanisole, also known as 2-nitroanisole and o-nitroanisole, is an organic compound mainly used in organic synthesis, the manufacture of dyes and drugs. At present, it is usually obtained by reacting o-nitrophenol with a methylating agent, and the methylating agent includes dimethyl carbonate and dimethyl sulfate. In the dimethyl carbonate method, methanol and carbon dioxide are generated as by-products, and the carbon atom utilization rate is only 1 / 3, which is contrary to the current trend of pursuing high carbon atom utilization and carbon dioxide emission reduction. In the dimethyl sulfate method, a large amount of three wastes are generated in the reaction, and dimethyl sulfate, as a highly toxic substance, was used as a military poison gas in World War I, which caused great damage to the human body. How to find a reaction system with high carbon atom utilization, low cost and safety is an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing o-nitroanisole, which uses a new catalyst to catalyze o-nitrophenol and methanol to generate o-nitroanisole. Compared with the dimethyl carbonate method and the dimethyl sulfate method, the carbon atom utilization rate of methanol is higher, which can reach 100% in theory, the price is lower, the safety and reliability are better, the reaction only produces water as a byproduct, and the production process is cleaner, which is an ideal process. The technical solution adopted by the present invention is as follows:

[0004] A method for preparing o-nitroanisole comprises the following steps:

[0005] Under the action of a catalyst, o-nitrophenol and methanol react to generate o-nitroanisole, wherein the catalyst is a composite catalyst in which silver type supported by SBA-15 and platinum type supported by niobium carbide multilayer nanosheets are mixed in a certain proportion.

[0006] In a preferred embodiment, the catalytic reaction of o-nitrophenol and methanol is carried out in a fixed bed; preferably, the amount of o-nitrophenol added is 5-30% of the total mass of o-nitrophenol and methanol.

[0007] In a preferred embodiment, the reaction temperature of o-nitrophenol and methanol is 260-340° C., and the reaction pressure is 0.3-0.8 bar(G).

[0008] In a preferred embodiment, the liquid hourly mass space velocity of o-nitrophenol is 0.1-0.5h -1 .

[0009] In another aspect, the present invention provides a method for preparing a SBA-15-supported silver-type and niobium carbide multilayer nanosheet-supported platinum-type composite catalyst, comprising the following steps:

[0010] (1) Add molecular sieve SBA-15 to the silver source aqueous solution and stir evenly;

[0011] (2) adjusting the pH of the solution in step (1) to a target value, and then drying and calcining to obtain an SBA-15-supported silver catalyst;

[0012] (3) adding niobium carbide multilayer nanosheets to the platinum source aqueous solution and stirring evenly;

[0013] (4) adjusting the pH of the solution in step (3) to a target value, and then drying and calcining to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets;

[0014] (5) The SBA-15-loaded silver catalyst prepared in step (2) and the niobium carbide multilayer nanosheet-loaded platinum catalyst prepared in step (4) are mixed in a certain ratio to obtain a composite catalyst.

[0015] In a specific embodiment, in step (1), the silver source includes one or more of silver chloride, silver acetylacetonate, silver fluoride, silver phosphate, silver benzoate or silver cyclohexylbutyrate, and the mass of water is 25-50 times the mass of the silver source; preferably, the amount of SBA-15 added is 30-45 times the mass of the silver source.

[0016] In a specific embodiment, in step (2), ammonia water is added to adjust the pH value to 7.5-8.5; preferably, the drying temperature is 110-130°C, and the drying time is 8-20h; more preferably, the calcination is carried out in an air atmosphere, the calcination temperature is 350-500°C, and the calcination time is 5-16h.

[0017] In a specific embodiment, in step (3), the platinum source includes one or more of platinum dichloride, platinum iodide, platinum acetylacetonate and platinum tetrachloride; the mass of water is 20-45 times the mass of the platinum source; preferably, the particle size of the niobium carbide multilayer nanosheets is 1-5 μm, and the added amount is 30-50 times that of the platinum source.

[0018] In a specific embodiment, in step (4), ammonia water is added to adjust the pH to 8.0-9.0; preferably, the drying temperature is 110-130°C, and the drying time is 8-20 hours; more preferably, the calcination is carried out in an air atmosphere, the calcination temperature is 400-550°C, and the calcination time is 10-18 hours.

[0019] In a specific embodiment, in the step (5), the mass of the silver-type catalyst supported by SBA-15 is 0.9-2.0 times the mass of the platinum-type catalyst supported by the niobium carbide multilayer nanosheets.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The method of the present invention realizes the utilization mode of o-nitrophenol and also provides a novel synthesis process of o-nitroanisole.

[0022] 2) The method of the present invention develops an efficient composite catalyst. Using a continuous fixed bed process, the conversion rate of o-methylphenol can reach 42%, the selectivity of o-nitroanisole can reach more than 93%, and it can operate continuously and stably for more than 3000 hours. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0025] Main raw material sources

[0026]

[0027]

[0028] Main test methods

[0029] Gas chromatography: The composition of the o-nitrophenol-methanol reaction solution was analyzed by gas chromatography. The operating conditions were: Shimadzu GC-2030 gas chromatograph, DB-5MS UI (20m×0.25mm×0.25μm) chromatographic column, acetonitrile as diluent. The vaporization chamber temperature was 300°C, the column flow rate was 1.00mL / min, and the injection volume was 0.2μL. The chromatographic column was programmed to heat: first, the temperature was increased from 40°C to 100°C at a heating rate of 2°C / min, and finally, the temperature was increased to 300°C at a heating rate of 10°C / min.

[0030] Reactor used in the embodiment: The reaction adopts a stainless steel fixed bed reactor, the inner diameter of the reaction tube is 19 mm, and Φ3 mmθ rings are filled at both ends of the catalyst.

[0031] Example 1

[0032] The preparation method of the catalyst is as follows:

[0033] (1) Dissolve 10 g of silver fluoride in pure water, where the mass of the water is 29 times the mass of the silver fluoride;

[0034] (2) adding SBA-15 to the above solution, wherein the amount of SBA-15 added is 41 times the mass of silver fluoride, and stirring evenly;

[0035] (3) adding 28% by mass aqueous ammonia to the solution of step (2) to adjust the pH to 7.9;

[0036] (4) drying the solution of step (3) at 120° C. for 12 h;

[0037] (5) calcining the dried sample in step (4) in an air atmosphere at 410° C. for 8 h to obtain an SBA-15-supported silver catalyst;

[0038] (6) Dissolve 10 g of platinum dichloride in pure water, the mass of water being 22 times that of platinum dichloride;

[0039] (7) adding niobium carbide multilayer nanosheets to the solution of step (6), wherein the particle size of the niobium carbide multilayer nanosheets is 3 μm and the amount added is 36 times the mass of platinum dichloride, and stirring evenly;

[0040] (8) adding 28% by mass of aqueous ammonia to the solution of step (7) to adjust the pH to 8.3;

[0041] (9) drying the solution in step (8) at 115° C. for 16 h;

[0042] (10) The dried sample in step (9) is calcined in an air atmosphere at 420° C. for 12 h to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets.

[0043] (11) The silver-type catalyst supported by SBA-15 and the platinum-type catalyst supported by niobium carbide multilayer nanosheets were mixed in a mass ratio of 1.6:1 to obtain the final composite catalyst.

[0044] The reaction conditions of o-nitrophenol and methanol are as follows:

[0045] The reaction of o-nitrophenol and methanol adopts a continuous fixed bed process. The amount of o-nitrophenol added is 29% of the total mass of o-nitrophenol and methanol. The reaction temperature of o-nitrophenol and methanol is 270°C, the reaction pressure is 0.7 bar(G), and the liquid hourly mass space velocity of o-nitrophenol is 0.4 h -1 .

[0046] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0047] Example 2

[0048] The preparation method of the catalyst is as follows:

[0049] (1) Dissolve 10 g of silver phosphate in pure water. The mass of the water is 35 times the mass of the silver acetylacetonate.

[0050] (2) adding SBA-15 to the above solution, wherein the amount of SBA-15 added is 38 times the mass of silver phosphate, and stirring evenly;

[0051] (3) adding 28% by mass aqueous ammonia to the solution of step (2) to adjust the pH to 8.1;

[0052] (4) drying the solution of step (3) at 110° C. for 16 h;

[0053] (5) calcining the sample dried in step (4) in an air atmosphere at 470° C. for 13 h to obtain an SBA-15-supported silver catalyst;

[0054] (6) Dissolve 10 g of platinum iodide in pure water, where the mass of water is 29 times that of platinum iodide;

[0055] (7) adding niobium carbide multilayer nanosheets to the solution of step (6), wherein the particle size of the niobium carbide multilayer nanosheets is 2 μm and the amount added is 48 times the mass of platinum iodide, and stirring evenly;

[0056] (8) adding 28% by mass of aqueous ammonia to the solution of step (7) to adjust the pH to 8.9;

[0057] (9) drying the solution in step (8) at 125° C. for 19 h;

[0058] (10) The dried sample in step (9) was calcined in an air atmosphere at 530° C. for 15 h to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets.

[0059] (11) The silver-type catalyst supported by SBA-15 and the platinum-type catalyst supported by niobium carbide multilayer nanosheets were mixed in a mass ratio of 1.9:1 to obtain the final composite catalyst.

[0060] The reaction conditions of o-nitrophenol and methanol are as follows:

[0061] The reaction of o-nitrophenol and methanol adopts a continuous fixed bed process. The amount of o-nitrophenol added is 25% of the total mass of o-nitrophenol and methanol. The reaction temperature of o-nitrophenol and methanol is 320°C, the reaction pressure is 0.5 bar(G), and the liquid hourly mass space velocity of o-nitrophenol is 0.3 h -1 .

[0062] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0063] Example 3

[0064] The preparation method of the catalyst is as follows:

[0065] (1) Dissolve 10 g of silver chloride in pure water. The mass of water is 42 times the mass of silver chloride.

[0066] (2) adding SBA-15 to the above solution, the amount of SBA-15 added is 32 times the mass of silver chloride, and stirring evenly;

[0067] (3) adding 28% by mass aqueous ammonia to the solution of step (2) to adjust the pH to 8.4;

[0068] (4) drying the solution of step (3) at 130° C. for 19 h;

[0069] (5) calcining the dried sample in step (4) under air atmosphere at 380° C. for 9 h to obtain an SBA-15-supported silver catalyst;

[0070] (6) Dissolve 10 g of platinum acetylacetonate in pure water, where the mass of water is 37 times that of platinum acetylacetonate;

[0071] (7) adding niobium carbide multilayer nanosheets to the solution of step (6), wherein the particle size of the niobium carbide multilayer nanosheets is 4 μm and the amount added is 31 times the mass of platinum acetylacetonate, and stirring evenly;

[0072] (8) adding 28% by mass of aqueous ammonia to the solution of step (7) to adjust the pH to 8.5;

[0073] (9) drying the solution in step (8) at 120° C. for 12 h;

[0074] (10) The dried sample in step (9) was calcined in an air atmosphere at 510° C. for 16 h to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets.

[0075] (11) The silver-type catalyst supported by SBA-15 and the platinum-type catalyst supported by niobium carbide multilayer nanosheets were mixed in a mass ratio of 1.1:1 to obtain the final composite catalyst.

[0076] The reaction conditions of o-nitrophenol and methanol are as follows:

[0077] The reaction of o-nitrophenol and methanol adopts a continuous fixed bed process. The amount of o-nitrophenol added is 18% of the total mass of o-nitrophenol and methanol. The reaction temperature of o-nitrophenol and methanol is 300°C, the reaction pressure is 0.4 bar(G), and the liquid hourly mass space velocity of o-nitrophenol is 0.2 h -1 .

[0078] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0079] Example 4

[0080] The preparation method of the catalyst is as follows:

[0081] (1) Dissolve 10 g of silver cyclohexylbutyrate in pure water, where the mass of the water is 31 times the mass of the silver cyclohexylbutyrate.

[0082] (2) adding SBA-15 to the above solution, wherein the amount of SBA-15 added is 44 times the mass of silver cyclohexylbutyrate, and stirring evenly;

[0083] (3) adding 28% by mass aqueous ammonia to the solution of step (2) to adjust the pH to 7.7;

[0084] (4) drying the solution of step (3) at 120° C. for 10 h;

[0085] (5) calcining the sample dried in step (4) in an air atmosphere at 430° C. for 11 h to obtain an SBA-15-supported silver catalyst;

[0086] (6) Dissolve 10 g of platinum tetrachloride in pure water, the mass of water being 43 times that of platinum tetrachloride;

[0087] (7) adding niobium carbide multilayer nanosheets to the solution of step (6), wherein the particle size of the niobium carbide multilayer nanosheets is 5 μm and the amount added is 42 times the mass of platinum tetrachloride, and stirring evenly;

[0088] (8) adding 28% by mass of aqueous ammonia to the solution of step (7) to adjust the pH to 8.7;

[0089] (9) drying the solution in step (8) at 130° C. for 15 h;

[0090] (10) The dried sample in step (9) is calcined in an air atmosphere at 460° C. for 18 h to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets.

[0091] (11) The silver-type catalyst supported by SBA-15 and the platinum-type catalyst supported by niobium carbide multilayer nanosheets were mixed in a mass ratio of 1.3:1 to obtain the final composite catalyst.

[0092] The reaction conditions of o-nitrophenol and methanol are as follows:

[0093] The reaction of o-nitrophenol and methanol adopts a continuous fixed bed process. The amount of o-nitrophenol added is 9% of the total mass of o-nitrophenol and methanol. The reaction temperature of o-nitrophenol and methanol is 330°C, the reaction pressure is 0.3 bar(G), and the liquid hourly mass space velocity of o-nitrophenol is 0.5 h -1 .

[0094] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0095] Comparative Example 1

[0096] The difference from Example 2 is that the catalyst used is only a silver-type catalyst supported by SBA-15.

[0097] Comparative Example 2

[0098] The difference from Example 2 is that the catalyst used is only a platinum-type catalyst supported by niobium carbide multilayer nanosheets.

[0099] Table 1 Conversion rate and selectivity of each example

[0100] Serial number o-Nitrophenol conversion rate % o-Nitroanisole selectivity % Example 1 63.3 98.5 Example 2 69.4 98.7 Example 3 72.5 98.1 Example 4 76.8 98.3 Comparative Example 1 25.9 92.4 Comparative Example 2 50.4 73.3

[0101] The catalyst prepared in Example 4 was used for life test. The specific reaction steps were the same as those in Example 4. After continuous operation for 3000 hours, the conversion rate was 75% and the selectivity was 98%. The activity and selectivity did not decrease significantly.

[0102] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing a SBA-15-supported silver-type and niobium carbide multilayer nanosheet-supported platinum-type composite catalyst, characterized in that: The following steps are involved: (1) Add molecular sieve SBA-15 to the silver source aqueous solution and stir evenly; (2) adjusting the pH of the solution in step (1), and then drying and calcining to obtain an SBA-15-supported silver catalyst; (3) adding niobium carbide multilayer nanosheets to the platinum source aqueous solution and stirring evenly; (4) adjusting the pH of the solution in step (3), and then drying and calcining to obtain a platinum-type catalyst supported by niobium carbide multilayer nanosheets; (5) The SBA-15-loaded silver catalyst prepared in step (2) and the niobium carbide multilayer nanosheet-loaded platinum catalyst prepared in step (4) are mixed to obtain the composite catalyst.

2. The method according to claim 1, characterized in that In the step (1), the silver source includes one or more of silver chloride, silver acetylacetonate, silver fluoride, silver phosphate, silver benzoate or silver cyclohexylbutyrate, and the mass of water is 25-50 times the mass of the silver source; Preferably, the amount of SBA-15 added is 30-45 times the mass of the silver source.

3. The method according to claim 1, characterized in that In the step (2), ammonia water is added to adjust the pH value to 7.5-8.5; Preferably, the drying temperature is 110-130°C and the drying time is 8-20h; Preferably, the calcination is carried out in an air atmosphere, the calcination temperature is 350-500° C., and the calcination time is 5-16 hours.

4. The method according to claim 1, characterized in that In the step (3), the platinum source includes one or more of platinum dichloride, platinum iodide, platinum acetylacetonate and platinum tetrachloride; Preferably, the mass of the water is 20-45 times the mass of the platinum source; Preferably, the particle size of the niobium carbide multilayer nanosheets is 1-5 μm, and the added amount is 30-50 times that of the platinum source.

5. The method according to claim 1, characterized in that In the step (4), adding aqueous ammonia to adjust the pH to 8.0-9.0; Preferably, the drying temperature is 110-130°C and the drying time is 8-20h; Preferably, the calcination is carried out in an air atmosphere, the calcination temperature is 400-550° C., and the calcination time is 10-18 hours.

6. The method according to claim 1, characterized in that In the composite catalyst of step (5), the mass of the silver-type catalyst supported by SBA-15 is 0.9-2.0 times the mass of the platinum-type catalyst supported by the niobium carbide multilayer nanosheets.

7. A method for preparing o-nitroanisole, characterized in that, Under the action of a catalyst, o-nitrophenol and methanol react to generate o-nitroanisole, wherein the catalyst is a composite catalyst prepared by the method according to any one of claims 1 to 6.

8. The method according to claim 7, characterized in that The added amount of o-nitrophenol is 5-30% of the total mass of o-nitrophenol and methanol.

9. The method according to claim 7, characterized in that: The reaction temperature is 260-340°C, and the reaction pressure is 0.3-0.8 barG.

10. The method according to claim 7, characterized in that The liquid mass space velocity of o-nitrophenol is 0.1-0.5h -1 .

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