CN104028289B - The method of chloro aminobenzen is prepared in titanium carbide loaded with nano metallic catalyst and reduction thereof - Google Patents

Abstract

The invention relates to a nanometer metal catalyst supported by titanium carbide and a method for preparing chloroaniline through reduction thereof, belonging to the field of organic synthesis and catalytic reaction. The technical problem to be solved by the present invention is to provide a titanium carbide-loaded nano-metal catalyst and a method for preparing chloroaniline by reduction thereof. Titanium carbide-supported nano-metal catalyst, which is prepared by layered titanium carbide as a catalyst carrier, and then supporting an active metal element on titanium carbide; the active metal element is one of ruthenium, rhodium, platinum, palladium or iridium or two. And the titanium carbide supported nano-metal catalyst of the present invention prepared by the present invention is used to reduce chloronitrobenzene to obtain chloroaniline. The titanium carbide prepared by the present invention uses titanium aluminum carbon as a raw material to prepare catalyst carrier titanium carbide, which has a wide range of sources, low price, and a simple preparation method. The catalyst of the present invention has high activity and high selectivity for hydrogenation of chloronitrobenzene, and can be prepared by reduction. The reaction conditions of chloroanilines are mild.

Description

Titanium carbide-supported nano-metal catalyst and its reduction method for preparing chloroaniline

technical field

The invention relates to a titanium carbide-loaded nanometer metal catalyst and a method for preparing chloroaniline through reduction thereof, belonging to the field of organic synthesis and catalytic reaction.

Background technique

Chloroaniline, the reduction product of chloronitrobenzene, has high application value and is an important raw material for the preparation of dyes, medicines, pesticides, insecticides, and herbicides. The industrial production methods of chloroaniline mainly include Fe-HCl reduction system with iron powder as reducing agent and metal catalyst catalytic hydrogenation system. Among them, the Fe-HCl reduction system produces a large amount of waste such as iron sludge (Fe ₃ O ₄ ) and other by-products, and the subsequent treatment is complicated and the environment is seriously polluted. Therefore, this production process has been eliminated by many countries. The catalytic hydrogenation preparation method has the characteristics of atom economy and environmental friendliness, which has become a research hotspot in recent years. The catalyst mainly uses transition metals such as ruthenium, rhodium, platinum, palladium and nickel as active components. The catalytic selectivity of the catalyst is unsatisfactory due to severe dechlorination side reactions. At present, the selectivity of hydrogenation of chloronitrobenzene to chloroaniline is mainly improved by adding dechlorination inhibitor and optimizing the properties of the catalyst. However, although the addition of the dechlorination inhibitor can improve the product selectivity through its interaction with the active metal, it inhibits the activity of the catalyst to a certain extent, and the addition of the inhibitor causes secondary pollution, and the subsequent treatment is complicated. Therefore, choosing a suitable carrier and using the interaction between the carrier and the metal to improve the selectivity of the catalyst for catalyzing chloronitrobenzene has a great development prospect.

The supports of the supported catalysts used in the reduction of chloronitrobenzene to prepare chloroaniline mainly include TiO ₂ , Al ₂ O ₃ , MgO, C, ZrO ₂ , Fe ₂ O ₃ , and then metal , thus obtaining a supported metal catalyst. The load-type catalyst prepared by using the above-mentioned substance as a carrier can basically achieve a conversion rate of 100% and a selectivity greater than 99% when used to reduce and prepare chloroaniline. The supported catalyst prepared by using the above-mentioned substances as a carrier can basically achieve a conversion rate of 100% when used to reduce and prepare chloroaniline, but there are problems such as low catalyst activity and selectivity, and complicated preparation methods for the catalyst carrier. Titanium carbide has a graphene-like two-dimensional layered structure. The wide application of graphene as a carrier-supported metal catalyst in the catalytic hydrogenation of nitro compounds proves that two-dimensional layered materials are a class of excellent catalyst supports. For example, graphene not only has a relatively large area, but also contains a large number of surface functional groups. Using it as a carrier to support nano-metal catalysts has a strong synergistic catalytic effect. However, graphene is generally prepared by chemical oxidation, which has disadvantages such as complex preparation methods and high costs, which limit its wide application.

At the same time, the patent application with the notification number CN101947444A mainly adopts attapulgite-loaded nano-palladium catalyst to reduce and prepare chloroaniline. Add hydrogen, control the pressure, temperature and time to 1MPa, 80°C, and 3h. After the reaction is complete, separate the solution to obtain chloroaniline. The reaction temperature is higher and the reaction time is longer.

Contents of the invention

The first technical problem to be solved by the present invention is to provide a nanometer metal catalyst supported by titanium carbide.

Titanium carbide-supported nano-metal catalyst of the present invention, it is prepared by layered titanium carbide as catalyst carrier, and then supports active metal element on titanium carbide; Said active metal element is ruthenium, rhodium, platinum, palladium or iridium one or two.

In order to obtain a titanium carbide-supported nano-metal catalyst with better performance, the mass of the active metal element is preferably 0.1% to 5% of the mass of the titanium carbide-supported nano-metal catalyst; more preferably, the mass of the active metal element is titanium carbide-supported nano-metal 1-3% of catalyst mass.

The second technical problem to be solved by the present invention is to provide a preparation method of titanium carbide supported nanometer metal catalyst.

The preparation method of titanium carbide supported nanometer metal catalyst of the present invention comprises the following steps:

a. Preparation of catalyst carrier

adding titanium aluminum carbon into the hydrofluoric acid aqueous solution, so that the aluminum in the titanium aluminum carbon is completely dissolved in the hydrofluoric acid aqueous solution, filtering to obtain a black precipitate, washing the black precipitate, and drying in vacuum to obtain a catalyst carrier;

b. Preparation of catalyst

Put the catalyst carrier into water, and then add the active metal elements that need to be loaded. The active metal elements are added in the form of metal compounds, and then reduced until the loaded metal elements are zero-valent. After the reduction is completed, continue to stir to disperse the metal evenly Filter out, wash the precipitate, and vacuum-dry to obtain a titanium carbide-supported nano-metal catalyst;

The active metal element is one or both of ruthenium, rhodium, platinum, palladium or iridium; the metal compound is one or both of chloroplatinic acid, chloropalladate, metal chloride and metal nitrate species; the metal chloride is ruthenium chloride, rhodium chloride, platinum chloride, palladium chloride or iridium chloride; the metal nitrate is ruthenium nitrate, rhodium nitrate, platinum Nitrates of palladium, palladium or iridium;

The reduction method is to reduce by adding a reducing agent until no bubbles are generated, or by adding a low-boiling point alcohol for reflux reduction, or by reducing the mixed gas at 300-500oC; the reducing agent is NaBH ₄ , KBH ₄ or NH ₃ ·BH _3. The alcohol with low boiling point is methanol, ethanol, n-propanol or isopropanol; the mixed gas is H ₂ /Ar mixed gas or H ₂ /N ₂ mixed gas.

In order not to waste hydrofluoric acid and achieve the purpose of etching, the solid-liquid ratio of titanium aluminum carbon and hydrofluoric acid aqueous solution described in step a is preferably 0.5～2.5:12～100g/mL, and the concentration of hydrofluoric acid aqueous solution is 40 ~50wt%.

Further, preferably, the solid-liquid ratio of the catalyst carrier to water in step b is 0.1-0.5:10-30 g/mL.

Further, preferably, the mass of the active metal element described in step b is 0.1% to 5% of the mass of the titanium carbide-supported nano-metal catalyst; more preferably, the mass of the active metal element is 1-3% of the mass of the titanium carbide-supported nano-metal catalyst .

Further, it is preferred that when adding a reducing agent in step b for reduction, the molar ratio of the active metal element to the reducing agent is 1:6 to 16; it is preferred that in step b, when adding a low-boiling point alcohol for reflux reduction, the ratio of the catalyst carrier to the low-boiling point alcohol The solid-liquid ratio is 1:50-70g/mL; preferably, when the mixed gas is used for reduction in step b, the volume content of hydrogen in the mixed gas is 5%.

The present invention reduces and prepares the method for chloroaniline, takes titanium carbide supported nano-metal catalyst and chloronitrobenzene prepared by the present invention and joins in the mixed solvent at a weight ratio of 1:25 to 35, the catalyst and the mixed solvent The ratio of solid to liquid is 1:1000~1800g/mL, and hydrogen gas is passed in, and the reaction temperature is 25~60°C, and the hydrogen pressure is 0.1MPa~1MPa to react until the reaction of chloronitrobenzene is complete. After the reaction is completed, after cooling Take out the reaction solution to obtain chloroaniline;

The mixed solvent is a mixed solvent of water and alcohol, and the alcohol is methanol, ethanol, n-propanol or isopropanol.

Further, it is preferred that the titanium carbide supported nano-metal catalyst and chloronitrobenzene are in a weight ratio of 1:30; preferably the solid-liquid ratio of the catalyst to the mixed solvent is 1:1400g/mL, preferably in the mixed solvent Water by volume: alcohol=2:5.

The present invention has following beneficial effect:

1. Titanium carbide has a graphene-like two-dimensional layered structure and a large specific surface area. The existing titanium carbide is mainly prepared by methods such as carbon reduction of silicon dioxide, gas phase method, metal thermal reduction method and direct reaction method. The titanium carbide prepared by hydrofluoric acid wet etching can effectively avoid the high-temperature (1700-2100oC) reaction step in the above-mentioned preparation method. In addition, titanium carbide prepared by hydrofluoric acid etching contains a large number of surface oxygen-containing functional groups such as surface hydroxyl groups, which can stabilize the metal nanoparticles on the catalyst surface and prevent the metal nanoparticles from agglomerating during the catalytic hydrogenation reaction. resulting in decreased activity.

2. The present invention uses water and alcohol with low boiling point as the mixed solvent, and utilizes the hydrogen bond between the surface hydroxyl group of the titanium carbide carrier and the solvent water, which can significantly improve the activity and selectivity of the catalyst and reduce the catalytic reaction conditions. Most of the reduction preparation of chloroaniline by using the supported metal catalyst prepared in the present invention can be carried out at normal temperature, and the reaction time is also shortened. The reaction time of the reduction preparation of chloroaniline in the present invention is 0.5-2h. For example, the titanium carbide-supported platinum catalyst prepared by the method of the present invention has a reaction temperature of 25° C. and a pressure of 0.1 MPa. After 40 minutes of reaction, 4-chloronitrobenzene can be completely converted, and the selectivity of 4-chloroaniline is greater than 99.9%.

3. The catalyst carrier titanium carbide is prepared by using titanium aluminum carbon as a raw material, which has wide sources, low price, and simple and convenient preparation method. The supported metal catalyst prepared on titanium carbide has high activity and high selectivity for the hydrogenation of chloronitrobenzene. When adopting the method provided by the invention to prepare supported platinum and platinum catalyst for catalytic hydrogenation of 4-chloronitrobenzene, the conversion rate of 4-chloronitrobenzene reaches 100%, and the selectivity of p-chloroaniline is greater than 99.9%. , The content of by-products produced by dechlorination side reactions is reduced to 0.1%.

4. After the reaction, the catalyst and the product are naturally separated, and the catalyst can be reused after centrifugation.

5. No inorganic or organic dechlorination inhibitor is added to the system of the present invention, which greatly simplifies the separation or purification process of the product and reduces the production cost.

detailed description

The first technical problem to be solved by the present invention is to provide a nanometer metal catalyst supported by titanium carbide.

The technical scheme of the present invention is: titanium carbide supported nanometer metal catalyst, which is prepared by layered titanium carbide as a catalyst carrier, and then supporting active metal elements on titanium carbide; the active metal elements are ruthenium, rhodium, platinum, palladium Or one or both of iridium.

Further, in order to achieve better catalytic activity, the mass of the active metal element is preferably 0.1% to 5% of the mass of the titanium carbide-supported nano-metal catalyst; more preferably the mass of the active metal element is the mass of the titanium carbide-supported nano-metal catalyst 1 to 3% of that.

The second technical problem to be solved by the present invention is to provide a preparation method of titanium carbide supported nanometer metal catalyst.

The preparation method of titanium carbide supported nanometer metal catalyst comprises the steps:

a. Preparation of catalyst carrier

adding titanium aluminum carbon into the hydrofluoric acid aqueous solution, so that the aluminum in the titanium aluminum carbon is completely dissolved in the hydrofluoric acid aqueous solution, filtering to obtain a black precipitate, washing the black precipitate, and drying in vacuum to obtain a catalyst carrier;

b. Preparation of catalyst

Put the catalyst carrier into water, and then add the active metal elements that need to be loaded. The active metal elements are added in the form of metal compounds, and then reduced until the loaded metal is zero-valent. After the reduction is completed, continue to stir to disperse the metal elements evenly. Filter out, wash the precipitate, and vacuum-dry to obtain a titanium carbide-supported nano-metal catalyst;

The active metal element is one or both of ruthenium, rhodium, platinum, palladium or iridium; the metal compound is one or both of chloroplatinic acid, chloropalladate, metal chloride and metal nitrate species; the metal chloride is ruthenium chloride, rhodium chloride, platinum chloride, palladium chloride or iridium chloride; the metal nitrate is ruthenium nitrate, rhodium nitrate, platinum The nitrate of nitrate, palladium or iridium; Preferably said metal compound is chloroplatinic acid, ruthenium trichloride, rhodium trichloride; Preferably said metal compound is the mixture of ruthenium trichloride and chloroplatinic acid ; Preferably the metal compound is a mixture of ruthenium trichloride and sodium chloropalladate;

The reduction method is to reduce by adding a reducing agent until no bubbles are generated, or by adding a low-boiling point alcohol for reflux reduction, or by reducing the mixed gas at 300-500oC; the reducing agent is NaBH ₄ , KBH ₄ or NH ₃ ·BH _3. The alcohol with low boiling point is methanol, ethanol, n-propanol or isopropanol; the mixed gas is H ₂ /Ar mixed gas or H ₂ /N ₂ mixed gas.

In the process of etching away aluminum in step a of the present invention, in order to make the reaction more complete, it is preferable to stir during the reaction, the stirring speed is 100-800 rpm, and further, the preferred stirring speed is 300 rpm, and the stirring is about 12-24 hours. etch completely.

In order not to waste the hydrofluoric acid aqueous solution, the preferred solid-liquid ratio of the titanium aluminum carbon to the hydrofluoric acid aqueous solution is 0.5-2.5:12-100 g/mL; the concentration of the hydrofluoric acid aqueous solution is preferably 40-50 wt%.

In order to fully remove the impurities on the titanium carbide, the washing in step a is preferably washed with water and ethanol respectively, more preferably washed 3 times respectively.

In order to fully dry the titanium carbide, the preferred vacuum drying temperature in step a is 50-70°C, preferably 60°C.

Preferably, the solid-liquid ratio of the catalyst carrier to water in step b is 0.1-0.5:10-30 g/mL, more preferably the solid-liquid ratio of the catalyst carrier to water in step b is 0.5:20 g/mL.

In the present invention, the active metal element is mainly added in the form of a metal compound, and then reduced, and the final metal on the catalyst is zero-valent metal.

Further, in order to achieve better catalytic activity, the mass of the active metal element is preferably 0.1% to 5% of the mass of the titanium carbide-supported nano-metal catalyst; more preferably the mass of the active metal element is the mass of the titanium carbide-supported nano-metal catalyst 1 to 3% of that. The amount of the metal compound is determined according to the amount of the active metal element in the finally formed titanium carbide-loaded nano-metal catalyst as the mass of the catalyst.

After the metal compound is mixed with the catalyst carrier, the active metal element is reduced to zero valence. The reduction method is mainly to add a reducing agent to reduce to no bubbles, or to add a low-boiling point alcohol for reflux reduction, or to pass a mixed gas at 300-500oC For reduction, the reducing agent is NaBH ₄ , KBH ₄ or NH ₃ ·BH ₃ , the low boiling point alcohol is methanol, ethanol, n-propanol or isopropanol; the mixed gas is H ₂ /Ar mixed gas or For the H ₂ /N ₂ mixed gas, the hydrogen content accounts for 5% of the volume of the mixed gas.

Among them, when adding a reducing agent for reduction, the molar ratio of the active metal element to the reducing agent is preferably 1:6-16, and the reduction time is 3-6 hours; when adding a low-boiling point alcohol for reflux reduction, the feed solution of the catalyst carrier and the low-boiling point alcohol is preferably The ratio is 1:50-70g/mL, and the reduction time is 6-10 hours; preferably, when the mixed gas is used for reduction in step b, the volume content of hydrogen in the mixed gas is 5%.

The completion of the reduction can be checked by X-ray photoelectron spectroscopy until the supported metal is zero-valent.

Stirring is still required after the reduction is completed in order to further disperse the active metal elements on the catalyst carrier evenly. It is preferable to continue stirring at a stirring speed of 600 rpm for 12 to 48 hours after the reduction is completed.

In step b, the precipitate is filtered out and washed, preferably with water and ethanol, respectively, and the number of washings is preferably 3 times.

After the washing in step b is completed, the catalyst needs to be vacuum-dried. The temperature of vacuum drying is preferably 50-70°C, more preferably 60°C.

The third technical problem to be solved by the present invention is to provide a method for reducing and preparing chloroanilines.

The method for preparing chloroaniline by reduction in the present invention is as follows: the titanium carbide-loaded nano-metal catalyst prepared in the present invention and chloronitrobenzene are added to the mixed solvent at a weight ratio of 1:25 to 35, and the catalyst and the mixed solvent The ratio of solid to liquid is 1:1000～1800g/mL, hydrogen gas is passed in, and the reaction temperature is 25～60℃, and the hydrogen pressure is 0.1MPa～1MPa to react until the reaction of chloronitrobenzene is complete. After the reaction is completed, cool Finally, the reaction solution is taken out to obtain chloroaniline;

The mixed solvent is a mixed solvent of water and alcohol, and the alcohol is methanol, ethanol, n-propanol or isopropanol.

The reaction time for reducing and preparing chloroaniline in the present invention is 0.5-2 hours.

The way to detect whether the reaction of chloronitrobenzene is complete is online sampling and gas chromatography analysis and detection.

Further, in order not to waste raw materials, it is preferred that the titanium carbide-supported nano-metal catalyst and chloronitrobenzene have a weight ratio of 1:30.

In order to make the reaction more complete, it is preferable to stir during the reaction, and the stirring speed is 800-1200rpm.

In order to achieve a good reduction effect, the preferred solid-liquid ratio of the catalyst to the mixed solvent is 1:1400 g/mL, preferably the volume ratio of water:alcohol in the mixed solvent is 2:5.

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples.

The preparation of embodiment 1 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 25g of titanium aluminum carbon to 1000mL concentrated hydrofluoric acid aqueous solution, the concentration of hydrofluoric acid aqueous solution is 40wt%, stir at room temperature for 12h, the stirring speed is 600rpm, the reaction solution is centrifuged to obtain a black precipitate, and the black precipitate is mixed with water and Washed three times with ethanol, and dried in vacuum at 60oC for 12h to obtain the carrier titanium carbide.

Weigh 5 g of the dried carrier titanium carbide and add it to 200 mL of water, add 50 mL of chloroplatinic acid aqueous solution containing 150 mg of platinum, then dropwise add 50 mL of aqueous solution containing 450 mg of NaBH ₄ for reduction until no bubbles are generated, and continue stirring for 24 hours after the reduction is completed , filtered out, washed three times with water and ethanol respectively, and vacuum-dried at 60oC for 12h to obtain a platinum catalyst supported on titanium carbide;

Transfer 50mg of catalyst, 1.57g of 4-chloronitrobenzene, 70mL of mixed solvent of water and methanol (volume ratio of water and methanol: 2:5) into a 250mL two-neck bottle, and feed hydrogen at a reaction temperature of 25oC and a hydrogen pressure of 1atm React 40min, stir during the reaction, the stirring speed is 800rpm, after the completion of the reaction, chloroaniline is obtained;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 99.9%.

The preparation of embodiment 2 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 0.5 g of the carrier titanium carbide prepared in Example 1 into 20 mL of water, add 5 mL of chloroplatinic acid aqueous solution containing 15 mg of platinum, then add 30 mL of isopropanol for reflux reduction for 8 h, continue stirring for 24 h after the reduction, and filter out. Wash with water and ethanol three times respectively, and dry in vacuum at 60°C for 12 hours to obtain a platinum catalyst supported on titanium carbide;

Transfer 50mg of catalyst, 1.57g of 4-chloronitrobenzene, 70mL of mixed solvent of water and methanol (volume ratio of water and methanol: 2:5) into a 250mL two-neck bottle, and feed hydrogen at a reaction temperature of 25oC and a hydrogen pressure of 1atm React for 1h, stir during the reaction, and the stirring speed is 1200rpm, and the chloroaniline is obtained after the reaction is completed;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 99.0%.

The preparation of embodiment 3 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 0.5 g of carrier titanium carbide prepared in Example 1 to 20 mL of water, add 5 mL of ruthenium trichloride aqueous solution containing 15 mg of ruthenium, then add dropwise ₅ mL of aqueous solution containing 56 mg of NaBH , continue stirring for 24 hours after the reduction is completed, and filter out , using water and ethanol to wash 3 times respectively, and vacuum drying at 60oC for 12h to obtain the titanium carbide supported ruthenium catalyst;

The prepared 50mg catalyst, 1.57g 4-chloronitrobenzene, 70mL of water and ethanol mixed solvent (water and ethanol volume ratio 1:6) were transferred to a 250mL autoclave, and hydrogen gas was introduced. The reaction temperature was 60oC and the hydrogen pressure was 1.0 React under MPa for 2h, stir during the reaction, the stirring speed is 1200rpm, cool after the completion of the reaction, remove the reaction solution, and obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 99.9%.

The preparation of embodiment 4 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 0.5 g of carrier titanium carbide prepared in Example 1 to 20 mL of water, add 5 mL of rhodium trichloride aqueous solution containing 15 mg of rhodium, then add dropwise ₅ mL of aqueous solution containing 52 mg of NaBH , continue stirring for 24 h after the reduction is completed, filter out, Adopt water and ethanol to wash 3 times respectively, 60 ℃ of vacuum drying 12h, can obtain titanium carbide supported rhodium catalyst;

The prepared 50mg catalyst, 1.57g 4-chloronitrobenzene and 70mL water and ethanol (water and ethanol volume ratio 2:5) were transferred to a 250mL two-neck bottle, and hydrogen gas was introduced. The reaction temperature was 25oC and the hydrogen pressure was 1.0atm Under reaction 30min, stir during reaction, and stirring speed is 1000rpm, and reaction completes and takes out reaction solution and obtains chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 99%.

The preparation of embodiment 5 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 0.5 g of carrier titanium carbide prepared in Example 1 into 20 mL of water, add ruthenium trichloride and 5 mL of chloroplatinic acid aqueous solution containing ruthenium and platinum total amount of 15 mg (the mass ratio of ruthenium to platinum is 1:1), and then Add dropwise 5 mL of an aqueous solution containing 50 mg of NaBH ₄ , continue stirring for 24 hours after the reduction is completed, filter out, wash with water and ethanol three times, and dry in vacuum at 60°C for 12 hours to obtain a titanium carbide-supported ruthenium-platinum catalyst;

The prepared 50mg catalyst, 1.57g4-chloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to a 250mL two-necked bottle, and hydrogen is passed into it. At a reaction temperature of 30°C, the hydrogen pressure is React at 1.0atm for 1h, stir during the reaction, and the stirring speed is 1000rpm;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 99.9%.

The preparation of embodiment 6 catalyst and adopt this catalyst reduction to obtain chloroaniline

Add 0.5 g of carrier titanium carbide prepared in Example 1 to 20 mL of water, add 5 mL of ruthenium trichloride and sodium chloropalladate aqueous solution containing 15 mg of ruthenium and palladium in total (the mass ratio of ruthenium to palladium is 1:1), Then add dropwise 5mL of aqueous solution containing _50mgNaBH , continue to stir for 24h after the reduction is completed, filter out, wash with water and ethanol three times respectively, and vacuum dry at 60°C for 12h to obtain a titanium carbide supported ruthenium palladium catalyst;

The prepared 50mg catalyst, 1.57g4-chloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to a 250mL two-necked bottle, and hydrogen is passed into it. At a reaction temperature of 30°C, the hydrogen pressure is React for 1 hour at 1.0 atm, stir during the reaction, and the stirring speed is 1000 rpm, take out the reaction solution after the reaction to obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 100%, and the selectivity of 4-chloroaniline was 96%.

Embodiment 7 adopts the catalyst reduction that embodiment 1 makes to obtain chloroaniline

The 50mg titanium carbide supported platinum catalyst prepared in Example 1, 1.57g2-chloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to 250mL two-necked bottle, and reaction temperature is 25 ℃, Feed in hydrogen, react for 1 hour at a hydrogen pressure of 1.0 atm, stir during the reaction, and the stirring speed is 1000 rpm, after the reaction is complete, take out the reaction solution to obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 2-chloronitrobenzene was 100%, and the selectivity of 2-chloroaniline was 99.6%.

Embodiment 8 adopts the catalyst reduction that embodiment 1 makes to obtain chloroaniline

The 50mg titanium carbide supported platinum catalyst prepared in Example 1, 1.57g2, 6-dichloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to 250mL two-necked bottle, pass into Hydrogen, the reaction temperature is 25oC, and the hydrogen pressure is 1.0atm to react for 2h, stir during the reaction, the stirring speed is 1000rpm, after the reaction is completed, take out the reaction solution to obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 2,6-dichloronitrobenzene was 100%, and the selectivity of 2,6-dichloroaniline was 99.6%.

Embodiment 9 adopts the catalyst reduction that embodiment 1 makes to obtain chloroaniline

The 50mg titanium carbide supported platinum catalyst prepared in Example 1, 1.57g2,5-dichloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to 250mL two-necked bottle, pass into Hydrogen, the reaction temperature is 25oC, and the hydrogen pressure is 1.0atm to react for 2h, stir during the reaction, the stirring speed is 1000rpm, after the reaction is completed, take out the reaction solution to obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 2,5-dichloronitrobenzene was 100%, and the selectivity of 2,5-dichloroaniline was 99%.

Embodiment 10 adopts the catalyst reduction that embodiment 1 makes to obtain chloroaniline

The titanium carbide supported platinum catalyst 50mg prepared in embodiment 1, 1.57g3,4-dichloronitrobenzene, water and ethanol mixed solvent 70mL (water and ethanol volume ratio 2:5) are transferred to 250mL two-necked bottle, pass into Hydrogen, the reaction temperature is 25oC, and the hydrogen pressure is 1 atm to react for 2h, stir during the reaction, and the stirring speed is 1000rpm, after the reaction is completed, take out the reaction solution to obtain chloroaniline;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 3,4-dichloronitrobenzene was 100%, and the selectivity of 3,4-dichloroaniline was 99%.

Embodiment 11 uses the catalyst reduction that embodiment 1 makes to obtain chloroaniline

By the method described in Example 1, the difference is that the solution after the reaction is taken out for analysis, the solid catalyst remains in the reactor, and 1.57g of 4-chloronitrobenzene, water and methanol mixed solvent 70mL (water and ethanol volume) are added Ratio 2:5), feed hydrogen, and react for 40min at a reaction temperature of 25°C and a hydrogen pressure of 1atm;

The reaction liquid was taken out and analyzed by gas chromatography, the conversion rate of 4-chloronitrobenzene was 99%, and the selectivity of 4-chloroaniline was 99.8%.

Claims (4)

1. reduction prepares the method for chloroaniline, is characterized in that: get titanium carbide supported nano-metal catalyst and chloronitrobenzene and join in mixed solvent by weight ratio 1:25～35, the material of described catalyst and mixed solvent The liquid ratio is 1:1000~1800g/mL, feed hydrogen, react at a reaction temperature of 25~60°C, and a hydrogen pressure of 0.1MPa~1MPa until the reaction of chloronitrobenzene is complete. After the reaction is complete, take it out after cooling. Reaction solution, obtains chloroaniline; Wherein, the titanium carbide-supported nano-metal catalyst is prepared from layered titanium carbide as a catalyst carrier, and then supports an active metal element on the titanium carbide; the active metal element is ruthenium, rhodium, platinum, palladium or iridium. one or two; The mixed solvent is a mixed solvent of water and alcohol, and the alcohol is methanol, ethanol, n-propanol or isopropanol. 2. The method for preparing chloroaniline by reduction according to claim 1, characterized in that: the mass of the active metal element is 0.1% to 5% of the mass of the titanium carbide supported nano-metal catalyst. 3. The method for preparing chloroaniline by reduction according to claim 1, characterized in that: the mass of the active metal element is 1% to 3% of the mass of the titanium carbide supported nano-metal catalyst. 4. The method for preparing chloroaniline by reduction according to any one of claims 1 to 3 is characterized in that: the titanium carbide supported nanometer metal catalyst and chloronitrobenzene are 1:30 by weight; The solid-liquid ratio of the catalyst to the mixed solvent is 1:1400g/mL; in the mixed solvent, the volume ratio of water:alcohol=2:5.