Catalyst for preparing 1, 3-cyclohexanedimethylamine through hydrogenation of m-xylylenediamine as well as preparation and application of catalyst

Abstract

The invention belongs to the technical field of catalytic hydrogenation, and particularly relates to a catalyst for preparing 1, 3-cyclohexanedimethylamine through hydrogenation of m-xylylenediamine as well as preparation and application of the catalyst. The preparation method comprises the following steps: preparing a magnesium-aluminum hydrotalcite precursor loaded with ruthenium active metal by adopting a coprecipitation method, treating the obtained precursor by using an alcohol treatment method, and further calcining and reducing to obtain the loaded magnesium-aluminum composite oxide catalyst. The method is simple and convenient to operate, and high-selectivity preparation of 1, 3-cyclohexanedimethylamine is realized under the condition that other alkali metal auxiliaries or inhibitors are not added by regulating and controlling the acid-base property of the surface of the catalyst by utilizing the characteristic that magnesium-aluminum hydrotalcite can still keep surface chemical properties after being calcined. The reaction conditions required by the catalyst are relatively mild, the preparation efficiency is high, the corrosion of alkali metal to a reaction container is avoided, the waste liquid treatment cost is reduced, and the catalyst has a certain industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic hydrogenation, and specifically relates to a catalyst for hydrogenating m-phenylenediamine to prepare 1,3-cyclohexylenediamine, and a preparation method and application thereof. Background Art

[0002] 1,3-cyclohexylenediamine is a product of complete hydrogenation of meta-xylylenediamine, an organic molecule belonging to the alicyclic subclass. As a curing agent, it has the advantages of fast curing speed, chemical corrosion resistance, and low-temperature curing. With the continuous development of the domestic epoxy resin market, the market demand for high-efficiency curing agents is increasing. After the commonly used curing agent meta-xylylenediamine was listed as a toxic chemical, the market demand for 1,3-cyclohexylenediamine as its replacement has also increased rapidly.

[0003] In previous studies, a reaction system of noble metal catalysts and alkali metal additives was often used to catalyze the preparation of 1,3-cyclohexylenediamine from m-phenylenediamine, and excellent activity results were achieved. Among them, alkali metals as electron donors can increase the electron density on the catalyst surface and strengthen the adsorption of the catalyst to the reactants. At the same time, since m-phenylenediamine contains two aminomethyl groups in its structure, side reactions such as demethylamine are prone to occur during the reaction. The addition of alkali metals will modify the surface of the catalyst, increase the alkalinity of the catalyst surface and the reaction solvent, and effectively inhibit the demethylamine side reaction. However, from a production perspective, the use of alkali metals will corrode the reaction vessel and greatly increase the treatment cost of the reaction waste liquid.

[0004] Therefore, there is an urgent need to develop a new catalytic hydrogenation catalyst that can exhibit high catalytic activity under mild reaction conditions without adding any alkali metal additives, and further catalyze the preparation of 1,3-cyclohexylenediamine from m-xylylenediamine, and the preparation method is easy and simple. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a catalyst for preparing 1,3-cyclohexylenediamine by hydrogenation of m-phenylenediamine, which can exhibit high catalytic activity under relatively economical and safe conditions, and the preparation method of the catalyst is simple.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a method for preparing a supported magnesium-aluminum composite oxide catalyst, the method comprising the following steps:

[0008] S1. dissolving a ruthenium salt (ruthenium is an active metal), a soluble magnesium salt and a soluble aluminum salt in water to obtain a solution A;

[0009] S2, dissolving the precipitant in water to obtain solution B;

[0010] S3, heating water to 60-80°C under stirring, then dropping solutions A and B thereinto at the same time, and maintaining the pH of the solution at 9-11 by controlling the dropping rate. After the dropping is completed, the resulting precipitate is allowed to stand at room temperature overnight;

[0011] S4, filtering and washing the precipitate obtained in step S3 until the filtrate is neutral, then redispersing it in an alcohol solution, and heating and stirring it until the alcohol solution is evaporated to dryness;

[0012] S5. After drying the precipitate obtained in step S4, the precipitate is placed in a reducing gas atmosphere for high-temperature reduction to obtain a supported magnesium-aluminum composite oxide catalyst.

[0013] The present invention uses ruthenium as an active metal and magnesium-aluminum composite oxide as a carrier, and regulates the acid-base properties of the catalyst itself, so that it can obtain an excellent target product yield in the reaction of catalyzing m-phenylenediamine to prepare 1,3-cyclohexanedimethylamine even without adding other alkaline additives or inhibitors. At the same time, the catalyst can perform transfer hydrogenation under a safer condition, and has a high conversion rate and selectivity. Moreover, the catalyst has a stable structure and stable performance, and after repeated recycling, it still has a high conversion rate and selectivity. In addition, the present invention synthesizes a single metal catalyst by a coprecipitation method, and its preparation method is simple, easy to operate, and has a very high preparation efficiency.

[0014] Preferably, the ruthenium salt is ruthenium chloride hydrate, the soluble magnesium salt is any one of magnesium nitrate, magnesium chloride and magnesium carbonate, and the soluble aluminum salt is any one of aluminum nitrate, aluminum chloride and aluminum sulfate.

[0015] Preferably, the precipitant is any one of sodium carbonate, sodium hydroxide and sodium bicarbonate, and the concentration of the precipitant is 1-1.5 mol / L.

[0016] Preferably, the alcohol solution is any one of methanol, ethanol, n-butanol and propanol.

[0017] Preferably, the reducing gas is a hydrogen-nitrogen mixed gas, and the proportion of hydrogen in the hydrogen-nitrogen mixed gas is 3-10%.

[0018] Preferably, the high temperature reduction is carried out at a temperature of 400-600°C, for a time of 2-4 hours, and at a heating rate of 4°-6° / min.

[0019] The second aspect of the present invention also provides a supported magnesium-aluminum composite oxide catalyst prepared by the preparation method described in the first aspect.

[0020] The third aspect of the present invention also provides the use of the supported magnesium-aluminum composite oxide catalyst described in the second aspect in hydrogenating m-xylylenediamine to produce 1,3-cyclohexylenediamine.

[0021] The fourth aspect of the present invention also provides a method for preparing 1,3-cyclohexylenediamine by catalytic hydrogenation of m-xylylenediamine, which specifically comprises: mixing m-xylylenediamine, the supported magnesium-aluminum composite oxide catalyst described in the second aspect and an organic solvent, heating and reacting under hydrogen pressurization after removing air, cooling and filtering after the reaction, and obtaining 1,3-cyclohexylenediamine.

[0022] Preferably, the mass ratio of the m-xylylenediamine to the supported magnesium-aluminum composite oxide catalyst is 1:0.1-0.2.

[0023] Preferably, the organic solvent is at least one of methanol, ethanol, isopropanol, tetrahydrofuran and toluene.

[0024] Preferably, the pressure of the hydrogen pressurization is 0.1-4Mpa.

[0025] Preferably, the heating reaction temperature is 100-180°C, and the time is 1-8h; further preferably, the heating reaction temperature is 100-140°C, and the time is 1-5h.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a supported magnesium aluminum composite oxide catalyst, which is obtained by calcining a precursor supported magnesium aluminum hydrotalcite, specifically, firstly using a coprecipitation method to prepare a magnesium aluminum hydrotalcite precursor loaded with ruthenium active metal, and using an alcohol treatment method to treat the obtained precursor, and then further calcining and reducing to obtain a supported magnesium aluminum composite oxide catalyst. The method is simple to operate, and utilizes the characteristics of magnesium aluminum hydrotalcite that can still maintain surface chemical properties after calcination. By regulating the acidity and alkalinity of the catalyst surface, it is possible to achieve high selectivity for the preparation of 1,3-cyclohexanedimethylamine without adding other alkali metal additives or inhibitors. The reaction conditions required for the catalyst are relatively mild, the preparation efficiency is high, and the corrosion of the reaction container by the alkali metal is avoided, the waste liquid treatment cost is reduced, and there is a certain industrial application prospect. Specifically, the present invention has the following advantages:

[0028] (1) Magnesium aluminum hydrotalcite is a carbonate-type magnesium aluminum double hydroxide with strong alkaline sites on the surface, and can maintain surface chemical properties even after calcination at a certain temperature. In the preparation process of the supported magnesium aluminum composite oxide catalyst, the present invention adjusts the acidity and alkalinity of the catalyst itself by matching magnesium and aluminum elements in different proportions, and then applies it to catalyze the preparation of 1,3-cyclohexylenediamine from m-xylenediamine. Even without the addition of other alkaline additives or inhibitors, the reaction can obtain excellent target product yields (the conversion rate of m-xylenediamine is 100%; the selectivity of 1,3-cyclohexylenediamine is greater than 95%, up to 99%), greatly reducing the processing cost.

[0029] (2) The present invention uses an alcohol solution to treat the catalyst, which can effectively improve the dispersibility of the active metal on the carrier surface and increase the specific surface area of ​​the catalyst, thereby providing more active sites.

[0030] (3) The catalyst provided by the present invention has good stability and recyclability, and after multiple cycles of use, it still has a high conversion rate and selectivity.

[0031] (4) The present invention synthesizes a single metal catalyst by a co-precipitation method, which has a simple preparation method, easy operation and high preparation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The activity data of the supported magnesium-aluminum composite oxide catalyst with different Mg:Al molar ratios catalyzing the preparation of 1,3-cyclohexylenediamine from m-xylylenediamine (different Mg:Al molar ratios of 1:1, 2:1, 3:1, 4:1, and 5:1 represent Examples 1, 2, 3, 4, and 5, respectively);

[0033] Figure 2 This is a SEM scanning electron microscope image of the supported magnesium-aluminum composite oxide catalyst with a lamellar structure obtained in Example 3;

[0034] Figure 3 The cycle performance of the supported magnesium-aluminum composite oxide catalyst prepared in Example 6 for catalyzing the preparation of 1,3-cyclohexylenediamine from m-xylylenediamine. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0037] Example 1: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0038] (1) 0.481 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.0753 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0039] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0040] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0041] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0042] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace, heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5%, and calcined for 3 h to obtain Catalyst 1.

[0043] (6) Using catalyst 1 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0044] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0045] The activity results of catalyst 1 are: the conversion rate of m-xylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 74% ( Figure 1 ).

[0046] Example 2: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0047] (1) 0.962 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0048] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0049] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0050] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0051] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5%, and calcined for 3 h to obtain Catalyst 2.

[0052] (6) Using catalyst 2 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0053] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0054] The activity results of catalyst 2 are: the conversion rate of m-xylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 80% ( Figure 1 ).

[0055] Example 3: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0056] (1) 1.44 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0057] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0058] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0059] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0060] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5%, and calcined for 3 h to obtain Catalyst 3.

[0061] (6) Using catalyst 3 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0062] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0063] The activity results of catalyst 3 are: the conversion rate of m-xylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 99% ( Figure 1 The catalyst prepared in this example was analyzed by electron microscope to observe its microstructure ( Figure 2 ).Depend on Figure 2It can be seen that the catalyst presents a lamellar stacking structure similar to rose petals, which is consistent with the structure of magnesium-aluminum hydrotalcite with a magnesium-aluminum molar ratio of 3:1 (Wu Hui, Wang Jihu, Wen Shaoguo, et al. Preparation of magnesium-aluminum hydrotalcite and study on the corrosion resistance of its coating [J]. Surface Technology (12): 126-134.).

[0064] Example 4: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0065] (1) 1.924 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.044 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain a solution A.

[0066] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0067] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0068] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0069] (5) The obtained precipitate was transferred to an oven and dried at 120°C for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600°C at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5%, and calcined for 3 h to obtain catalyst 4.

[0070] (6) Using catalyst 4 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0071] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0072] The activity results of catalyst 4 are: the conversion rate of m-xylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 78% ( Figure 1 ).

[0073] Example 5: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0074] (1) 2.405 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain a solution A.

[0075] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0076] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0077] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0078] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5% and calcined for 3 h to obtain Catalyst 5.

[0079] (6) Using catalyst 5 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0080] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0081] The activity results of catalyst 5 are: the conversion rate of m-xylylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 89% ( Figure 1 ).

[0082] Example 6: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0083] (1) 1.44 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0084] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0085] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0086] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of 99% ethanol and heated at 400 rpm and 60° C. until the ethanol was evaporated.

[0087] (5) The obtained precipitate was transferred to an oven and dried at 120°C for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600°C at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5% and calcined for 3 h to obtain Catalyst 6.

[0088] (6) Using catalyst 6 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0089] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0090] The activity results of Catalyst 6 are as follows: the conversion of m-xylylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 86% (Table 1).

[0091] Example 7: Preparation method of a supported magnesium-aluminum composite oxide catalyst and its application in catalytic hydrogenation of m-xylylenediamine to prepare 1,3-cyclohexylenediamine

[0092] (1) 1.44 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0093] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0094] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0095] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of methanol and heated at 400 rpm and 60° C. until the methanol was evaporated.

[0096] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5% and calcined for 3 h to obtain catalyst 7.

[0097] (6) Using catalyst 7 to catalyze meta-phenylenediamine to prepare 1,3-cyclohexylenediamine, specifically as follows:

[0098] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out at 100°C and 400rpm stirring rate for 4h. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction liquid was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result.

[0099] The activity results of catalyst 7 are as follows: the conversion of m-xylylenediamine is 100%, and the selectivity of 1,3-cyclohexylenediamine is 93% (Table 1).

[0100] Example 8: Preparation of supported magnesium-aluminum composite oxide catalyst and catalytic cycle performance of hydrogenation of m-phenylenediamine to 1,3-cyclohexanedimethylamine

[0101] (1) 1.44 g of magnesium nitrate hexahydrate, 0.7034 g of aluminum nitrate nonahydrate, and 0.092 g of ruthenium chloride hydrate were dissolved in 150 mL of deionized water and stirred at 400 rpm for 30 minutes to obtain solution A.

[0102] (2) Dissolve 5.3 g of anhydrous sodium carbonate in 50 mL of deionized water and stir at 400 rpm for 30 min to obtain solution B.

[0103] (3) Take 100 mL of deionized water C and place it on a magnetic stirrer, set the stirring speed to 400 rpm, and heat it to 80°C. Then, add solutions A and B to solution C simultaneously, controlling the dripping rate so that the pH of solution C is maintained at 10. After the dripping is completed, let it stand at room temperature overnight.

[0104] (4) The obtained precipitate was filtered and washed with deionized water until the filtrate was neutral, and then the precipitate was dispersed in 100 mL of n-butanol and heated at 400 rpm and 80° C. until the n-butanol was evaporated.

[0105] (5) The obtained precipitate was transferred to an oven and dried at 120° C. for 12 h. The dried precipitate was transferred to a tubular furnace and heated to 600° C. at a heating rate of 5° / min in an atmosphere of a hydrogen-nitrogen mixed gas with a hydrogen content of 5%, and calcined for 3 h to obtain catalyst 8.

[0106] (6) Catalyst 8 is used to perform a catalyst cycle performance test, comprising the following steps:

[0107] Add 0.15 g of m-xylylenediamine, 0.03 g of catalyst, and 20 mL of tetrahydrofuran into a 100 mL autoclave, and purge the autoclave with hydrogen to remove dissolved O 2 and the air in the kettle, and then 4Mpa hydrogen was introduced, and the reaction was carried out for 4 hours at 100°C and 400rpm stirring rate. After the reaction was completed, the reactor was quickly cooled to room temperature, the reaction solution was taken out and filtered to obtain a solution containing the target product 1,3-cyclohexyldimethylamine, and the solution was analyzed by gas chromatography to obtain the activity result. The catalyst obtained by filtration was washed three times with tetrahydrofuran, then placed in a vacuum oven, dried at -0.1Mpa and 80°C for 12 hours, and used for the next reaction after drying, and then reused four times.

[0108] The activity results of catalyst 8 after five uses are: conversion rate: 100%, 100%, 100%, 100%, 100%; selectivity: 99%, 96%, 94%, 88%, 97% ( Figure 3 ).

[0109] Table 1 Specific surface properties and catalytic performance of the catalysts obtained in Examples 3, 6 and 7

[0110]

[0111] As can be seen from Table 1, different alcohol solution treatments will have different effects on the specific surface area, pore volume and pore size of the catalyst, thereby affecting the catalytic performance.

[0112] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims

1. A method for preparing a supported magnesium-aluminum composite oxide catalyst, It is characterized in that The following steps are involved: S1. dissolving a ruthenium salt (ruthenium is an active metal), a soluble magnesium salt and a soluble aluminum salt in water to obtain a solution A; S2, dissolving the precipitant in water to obtain solution B; S3, heating water to 60-80°C under stirring, then dropping solutions A and B thereinto at the same time, and maintaining the pH of the solution at 9-11 by controlling the dropping rate. After the dropping is completed, the resulting precipitate is allowed to stand at room temperature overnight; S4, filtering and washing the precipitate obtained in step S3 until the filtrate is neutral, then redispersing it in an alcohol solution, and heating and stirring it until the alcohol solution is evaporated to dryness; S5. After drying the precipitate obtained in step S4, the precipitate is placed in a reducing gas atmosphere for high-temperature reduction to obtain a supported magnesium-aluminum composite oxide catalyst.

2. A method for preparing a supported magnesium-aluminum composite oxide catalyst according to claim 1, It is characterized in that The ruthenium salt is ruthenium chloride hydrate, the soluble magnesium salt is any one of magnesium nitrate, magnesium chloride and magnesium carbonate, and the soluble aluminum salt is any one of aluminum nitrate, aluminum chloride and aluminum sulfate.

3. The method for preparing a supported magnesium-aluminum composite oxide catalyst according to claim 1, It is characterized in that The precipitant is any one of sodium carbonate, sodium hydroxide and sodium bicarbonate, and the concentration of the precipitant is 1-1.5 mol / L.

4. The method for preparing a supported magnesium-aluminum composite oxide catalyst according to claim 1, It is characterized in that The alcohol solution is any one of methanol, ethanol, n-butanol and propanol.

5. The method for preparing a supported magnesium-aluminum composite oxide catalyst according to claim 1, It is characterized in that The reducing gas is a hydrogen-nitrogen mixed gas, and the proportion of hydrogen in the hydrogen-nitrogen mixed gas is 3-10%.

6. The method for preparing a supported magnesium-aluminum composite oxide catalyst according to claim 1, It is characterized in that The high temperature reduction is carried out at a temperature of 400-600°C, for a time of 2-4 hours, and at a heating rate of 4°-6° / min.

7. A supported magnesium-aluminum composite oxide catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the supported magnesium-aluminum composite oxide catalyst according to claim 7 in hydrogenating m-xylylenediamine to produce 1,3-cyclohexylenediamine.

9. A method for preparing 1,3-cyclohexylenediamine by catalytic hydrogenation of m-xylylenediamine, It is characterized in that Mix m-phenylenediamine, the supported magnesium-aluminum composite oxide catalyst according to claim 7 and an organic solvent, remove air, and heat the mixture under hydrogen pressure to react. After the reaction, cool and filter to obtain 1,3-cyclohexylenediamine.

10. The method for preparing 1,3-cyclohexylenediamine by catalytic hydrogenation of m-xylylenediamine according to claim 9, It is characterized in that The mass ratio of the meta-xylylenediamine to the supported magnesium-aluminum composite oxide catalyst is 1:0.1-0.2.

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