A poly-ionic liquid derived carbon-coated metal catalyst and preparation and application thereof

Abstract

The application discloses a polyionic liquid derivative carbon-coated metal catalyst and a preparation and application thereof. The preparation method is carried out according to the following steps: step one: obtaining an activated carbon / AIBN suspension liquid; step two: obtaining an activated carbon / AIBN suspension liquid loaded with platinum; step three: dissolving 1-ethyl-3-vinylimidazole nitrate in a mixed solution of ethanol and water, slowly adding the activated carbon / AIBN suspension liquid loaded with platinum into the solution after oxygen removal, stirring and polymerizing at 60-70 DEG C for 12-24 hours under nitrogen protection, and then performing suction filtration to obtain a polyionic liquid modified activated carbon loaded platinum catalyst precursor; step four: drying; and step five: calcining to obtain the polyionic liquid derivative carbon-coated metal catalyst. The application provides application of the polyionic liquid derivative carbon-coated metal catalyst in a catalytic hydrogenation reaction of chloronitrobenzene, and the catalyst has excellent activity, selectivity and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of polyionic liquid derivative carbon-coated metal catalyst and its preparation and application in chloronitrobenzene catalytic hydrogenation reaction. BACKGROUND

[0002] Chloroaniline is a colorless to light yellow oily liquid, is the raw material of herbicide chlorsulfuron. In the dye industry, it is an important dye intermediate, which is used for ice dye color base; it can also be used as diazonium component of azo dye, to produce acid black, acid blue and organic lake water solid yellow R, permanent red FR, han sand yellow HR, etc. And can be used to prepare medicine, pesticide, polyurethane resin crosslinking agent methyl dichloroaniline is an important organic intermediate in fine chemical industry.

[0003] At present, the process for preparing chloroaniline in industry mainly uses catalytic hydrogenation reduction of corresponding chloronitrobenzene. Its reaction mechanism is shown as follows.

[0004]

[0005] Hydrogenation reaction mechanism of chloronitrobenzene

[0006] The hydrogenation of halogenated nitro compound is a relatively complex chemical reaction process, which includes parallel reaction and consecutive reaction, and different hydrogenation intermediates may be generated. As shown above, there are two different reaction routes for the hydrogenation of chloronitrobenzene. Chloronitrobenzene generates chlorophenyl hydroxylamine under the action of hydrogen, and then dehydrates to generate chloroaniline. If the activity of the catalyst is relatively strong, it will lead to over-hydrogenation, and further dechlorination occurs to generate aniline or chlorobenzene.

[0007] At present, the processes reported for the production of chloroaniline mainly include the following: iron scrap reduction method, which is mature, simple, and easy to control, but has problems such as large equipment, large amount of reaction heat difficult to recover, large consumption of iron powder, difficulty in realizing continuous production, slow reaction speed, and difficult product separation, resulting in low production efficiency; sulfidic alkali reduction method, which is used by most enterprises to produce chloroaniline. Compared with the iron scrap reduction method, the reaction conditions are relatively mild, and the product is easy to separate, but the alkali liquor has serious environmental pollution problems, high cost and low yield; electrochemical reduction method, which is environmentally friendly and has mild reaction conditions, but needs to overcome problems such as high energy consumption, short service life of the diaphragm and low activity of the electrode; and catalytic hydrogenation reduction method, which is relatively green and clean, simple process, and does not easily cause large-scale discharge of acid and alkali liquor, is one of the most popular methods at present, but has dechlorination side reactions, so improving the performance of the catalyst to improve the selectivity of the reaction has been widely valued.

[0008] The coated catalyst is wrapped with an active substance inside, and a protective film is formed outside. This coating not only protects the catalyst from the external environment, can resist high temperature, high pressure and corrosion of corrosive substances, prevent the agglomeration and loss of metal nanoparticles, prolong the service life of the catalyst, but also can accurately control the reaction activity and selectivity of the catalyst by adjusting the thickness, composition and structure of the coating, thereby improving the efficiency of the catalytic reaction and the purity of the product.

[0009] Ionic liquids (ILs) have been shown to effectively improve the stability of metal nanoparticles. The protective layer introduced by ILs provides electrostatic protection against aggregation. However, there is currently no report of using ILs to enhance the stability of SACs without compromising activity. Considering the remarkable success of ionic liquids in NP and homogeneous catalysis, we propose that ionic liquid-induced electrostatic stabilization may be a viable strategy to enhance the stability of single-atom catalysts. We also envisage that the electronic modification of isolated metal atoms by charged cations or anions may lead to an increase in catalytic activity and selectivity.

[0010] In summary, it is urgent to find a coated catalyst with high dispersion, high activity, high selectivity and high stability for catalytic hydrogenation system. SUMMARY

[0011] One of the purposes of the present application is to provide a preparation method of a poly-ionic liquid derived carbon-coated metal catalyst, which is provided with a nitrogen-doped carbon layer by poly-1-ethyl-3-vinylimidazole nitrate, not only providing protection for the active center, but also promoting electron transmission between carbon layers due to the conductive properties of the carbon layer derived from poly-1-ethyl-3-vinylimidazole nitrate itself.

[0012] The second purpose of the present application is to provide a poly-ionic liquid derived carbon-coated metal catalyst.

[0013] The third purpose of the present application is to provide the application of the poly-ionic liquid derived carbon-coated metal catalyst in the catalytic hydrogenation reaction of chloronitrobenzene, which has excellent activity, selectivity and stability.

[0014] To achieve the above-mentioned purposes of the application, the technical scheme adopted by the present application is as follows:

[0015] In the first aspect, the present application provides a preparation method of a poly-ionic liquid derived carbon-coated metal catalyst, which is carried out according to the following steps:

[0016] Step one: dissolve activated carbon and azobisisobutyronitrile (AIBN) in a mixed solution of ethanol and water, blow nitrogen to remove oxygen, and obtain an activated carbon / AIBN suspension;

[0017] Step two: under vigorous stirring, drop the ethanol solution of chloroplatinic acid hexahydrate into the suspension obtained in step one to obtain a platinum-loaded activated carbon / AIBN suspension;

[0018] Step three: dissolve 1-ethyl-3-vinylimidazole nitrate in a mixed solution of ethanol and water, and slowly add the platinum-loaded activated carbon / AIBN suspension obtained in step two after oxygen removal, and stir at 60-70°C for 12-24h under nitrogen protection to obtain a polymer ionic liquid modified activated carbon supported platinum catalyst precursor; the weight ratio of activated carbon to 1-ethyl-3-vinylimidazole nitrate in the platinum-loaded activated carbon / AIBN suspension is 1:0.2-1;

[0019] Step four: dry the polymer ionic liquid modified activated carbon supported platinum catalyst precursor obtained in step three;

[0020] Step five: first, the product obtained in step four is calcined under a hydrogen atmosphere, and then calcined under an inert gas atmosphere, and the obtained product is a poly ionic liquid derived carbon-coated metal catalyst, named as M / C@PIL-X-Y, wherein "M" represents metal, "X" represents the hydrogen calcination temperature, "Y" represents the inert gas calcination temperature, "@" represents coating, " / " represents loading, and "PIL" represents poly ionic liquid.

[0021] The 1-ethyl-3-vinylimidazole nitrate described in the application can be prepared according to the literature [Gao J, Cao J, Yin Z, et al. A Facilitate Process to Prepare Hydrophilic Ionic Liquid Monomers Free Of Halide Impurity and Their Electrochemical Properties. [J]. International Journal of Electrochemical Science, 2013, 8: 4914-4923.].

[0022] Preferably, in step one, the mass ratio of activated carbon to AIBN is 1:0.005-1, and more preferably 1:0.005-0.01.

[0023] Preferably, in step one or three, the volume ratio of ethanol to water in the mixed solution of ethanol and water is 10:6-10, and more preferably 10:7.

[0024] Preferably, in step two, the concentration of the ethanol solution of chloroplatinic acid hexahydrate is 0.05-0.15g / mL, and more preferably 0.1g / mL.

[0025] As preferred, in step two, the mass fraction ratio of platinum contained in the ethanol solution of chloroplatinic acid hexahydrate to activated carbon is 2.5-3.5%:1, more preferably 3%:1.

[0026] As preferred, in step three, the weight ratio of activated carbon to 1-ethyl-3-vinylimidazole nitrate is 1:0.6.

[0027] As preferred, in step four, the drying condition is that the drying temperature is 60-80℃ and the drying time is 8-12h.

[0028] As preferred, in step five, the heating rate is 10℃ / min, the hydrogen reduction condition is 100-200℃ for 2h, and the N2 calcination condition is 450-500℃ for 2h.

[0029] In the second aspect, the application provides a poly ionic liquid derived carbon coated metal catalyst prepared by the preparation method according to the first aspect.

[0030] In the third aspect, the application provides an application of the poly ionic liquid derived carbon coated metal catalyst in a catalytic hydrogenation reaction of chloronitrobenzene.

[0031] The chloronitrobenzene according to the application is one of the following:

[0032]

[0033] The preferred chloronitrobenzene is o-chloronitrobenzene.

[0034] As preferred, the application specifically refers to adding chloronitrobenzene, a solvent and the poly ionic liquid derived carbon coated metal catalyst into a high-pressure reaction kettle, purging air with nitrogen, and then stirring and reacting with hydrogen to generate chloroaniline.

[0035] As preferred, the solvent is ethanol.

[0036] As preferred, the mass amount of the poly ionic liquid derived carbon coated metal catalyst is 1-5% of the mass of chloronitrobenzene, and most preferably 2-3%.

[0037] As preferred, the mass-volume ratio of chloronitrobenzene to solvent is 10g:(50-100)mL.

[0038] As preferred, the hydrogen pressure is maintained at 0.7-1.2MPa, and more preferably the hydrogen pressure is 1.0MPa, and the reaction temperature is controlled at 60-70℃, and most preferably at 70℃.

[0039] As preferred, the stirring rate is 500-1000rpm.

[0040] Compared with the prior art, the application has the following advantages:

[0041] (1) The polyionic liquid derived carbon-coated metal catalyst provided by the application uses a polymer polyionic liquid as a carbon and nitrogen source for a shell layer, applies the polyionic liquid to a thermal catalytic reaction, improves the binding energy of metal atoms through nitrogen doping, and thus improves the catalyst activity.

[0042] (2) The polyionic liquid derived carbon-coated metal catalyst provided by the application is polymerized in situ on the metal surface and completely coats the metal, bypassing the problem of weak bonding force between the ionic liquid and the metal surface, and is applied indirectly to the polyionic liquid, which is different from the partial coating of mesoporous catalysts, and the manufacturing method is simple and the application of the polyionic liquid is more efficient.

[0043] (3) The polyionic liquid derived carbon-coated metal catalyst provided by the application uses AIBN as a free radical initiator during preparation, which not only makes 1-ethyl-3-vinylimidazole nitrate more easily adhere to the metal surface, polymerizes in situ on the metal surface, and realizes complete coating, but also helps the contact of 1-ethyl-3-vinylimidazole nitrate in the solution, increasing the polymerization efficiency.

[0044] (4) The polyionic liquid derived carbon-coated metal catalyst provided by the application uses a direct graphite nitrogen introduction method to regulate the activity of the catalyst, and the content of graphite nitrogen in the catalyst can be regulated by adjusting the calcination temperature, thereby affecting the catalyst activity.

[0045] (5) The polyionic liquid derived carbon-coated metal catalyst provided by the application is completely coated with a polyionic liquid carbon layer on the metal surface, which assists in the electron transfer between the active metal in the core and the reaction substrate, making the catalyst have high activity; the outer shell layer protects the core metal, preventing the aggregation of single atoms, making the catalyst have high stability.

[0046] (6) The polyionic liquid derived carbon-coated metal catalyst provided by the application is applied to a catalytic hydrogenation system, and chloronitrobenzene hydrogenation catalysis to generate chloroaniline is selected as a probe reaction, the byproduct generated is less, the selectivity is high, and the corrosion of the equipment is reduced; the catalyst has good stability and can be repeatedly used; the safety is high during use; and the catalyst has high industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1a 、 Figure 1b 、 Figure 1c are TEM images of Pt / C (model number: T3EQ1, Shaanxi Ruikexin Material Co., Ltd.), Pt / C@IL-150-500 (comparative example 2), and Pt / C@PIL-150-500 (example 1), respectively. DETAILED DESCRIPTION

[0048] The technical solutions of the present application are further described below with specific examples. It is necessary to point out that the examples are only used to further illustrate the present application, but cannot be understood as limiting the protection scope of the present application, and the present application is not limited to this in any way.

[0049] The specific conditions not indicated in the examples of the present application are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not indicated by the manufacturer are conventional products that can be obtained by conventional technical means or purchased on the market.

[0050] The coconut shell activated carbon used in the examples of the present application is purchased from Chengde Tianyuan Activated Carbon Co., Ltd., with a specification of 20-40 mesh and an iodine value of 1000; and the platinum liquid is an ethanol solution of chloroplatinic acid hexahydrate.

[0051] Comparative Example 1: Preparation method of poly-1-ethyl-3-vinylimidazole nitrate

[0052] Under ice bath, 4.0956 g of diethyl sulfate was added dropwise into 2.5 g of vinyl imidazole, and stirred at 800 rpm for 3 h. The reacted solution was added dropwise into an ethanol solution dissolving 2.2358 g of KOH, and after stirring at high speed for 0.5 h, a clear filtrate was obtained by suction filtration. Molar amount of dilute nitric acid equivalent to KOH was added dropwise into the solution, and after stirring for 0.5 h, the filtrate obtained by suction filtration was rotary evaporated to obtain a light yellow viscous liquid, which was washed with 10 ml of diethyl ether for 3 times, and dried at 40℃ under vacuum for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0053] 0.6 g of 1-ethyl-3-vinylimidazole nitrate was dissolved in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and after deoxidation, 0.006 g of AIBN was added. Under nitrogen protection, polymerization was carried out at 65℃ for 24 h under stirring to obtain poly-1-ethyl-3-vinylimidazole nitrate.

[0054] Example 1

[0055] Under ice bath, 4.0956 g of diethyl sulfate was added dropwise into 2.5 g of vinyl imidazole, and stirred at 800 rpm for 3 h. The reacted solution was added dropwise into an ethanol solution dissolving 2.2358 g of KOH, and after stirring at high speed for 0.5 h, a clear filtrate was obtained by suction filtration. Molar amount of dilute nitric acid equivalent to KOH was added dropwise into the solution, and after stirring for 0.5 h, the filtrate obtained by suction filtration was rotary evaporated to obtain a light yellow viscous liquid, which was washed with 10 ml of diethyl ether for 3 times, and dried at 40℃ under vacuum for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0056] Dissolve 1 g of coconut shell activated carbon and 0.006 g of AIBN in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and blow nitrogen to remove oxygen. Add 797 μL of 0.1 g / mL chloroplatinic acid hexahydrate ethanol solution, which has been deoxygenated, to the activated carbon / AIBN suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. Dissolve 0.6 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and slowly add the platinum-loaded activated carbon / AIBN suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid-modified activated carbon-supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, and pass hydrogen gas. Increase the temperature from room temperature to 150°C at a rate of 10°C / min, and reduce the platinum with hydrogen for 2 h. Switch to nitrogen, and continue to increase the temperature from 150°C to 500°C at a rate of 10°C / min, and then calcine with nitrogen for 2 h. Thus, a polymeric ionic liquid-derived carbon-coated metal catalyst, denoted as Pt / C@PIL-150-500, is obtained.

[0057] Example 2

[0058] Under an ice bath, add 4.0956 g of diethyl sulfate dropwise to 2.5 g of vinyl imidazole, and stir at 800 rpm for 3 h. Add the reaction solution dropwise to an ethanol solution in which 2.2358 g of KOH is dissolved, and perform suction filtration after stirring vigorously for 0.5 h to obtain a clear filtrate. Add dilute nitric acid in an amount equivalent to the molar amount of KOH dropwise to the solution, and perform suction filtration after stirring for 0.5 h to obtain a filtrate. Perform rotary evaporation on the filtrate to obtain a light yellow viscous liquid, and then wash the liquid with 10 mL of diethyl ether three times. Perform vacuum drying at 40°C for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0059] Dissolve 1 g of coconut shell activated carbon and 0.006 g of AIBN in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, blow nitrogen to remove oxygen, and then add 797 μL of 0.1 g / mL chloroplatinic acid hexahydrate ethanol solution, which has been deoxygenated, to the activated carbon / AIBN suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. Dissolve 0.2 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and then slowly add the platinum-loaded activated carbon / AIBN suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid-modified activated carbon-supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, and then pass hydrogen gas, heat it from room temperature to 150°C at a rate of 10°C / min, reduce it with hydrogen for 2 h, switch to nitrogen, and then continue to heat it from 150°C to 500°C at a rate of 10°C / min, and then calcine it with nitrogen for 2 h. Thus, a polymeric ionic liquid-derived carbon-coated metal catalyst is prepared, which is denoted as Pt / C@PIL-150-500.

[0060] Example 3

[0061] Under an ice bath, add 4.0956 g of diethyl sulfate dropwise to 2.5 g of vinyl imidazole, and then stir at 800 rpm for 3 h. Then, add the reaction solution dropwise to an ethanol solution in which 2.2358 g of KOH has been dissolved, and then perform suction filtration after stirring vigorously for 0.5 h to obtain a clear filtrate. Add dilute nitric acid in an amount equivalent to the molar amount of KOH dropwise to the solution, and then perform suction filtration after stirring for 0.5 h to obtain a filtrate. Perform rotary evaporation on the filtrate to obtain a light yellow viscous liquid, wash it with 10 mL of diethyl ether three times, and then perform vacuum drying at 40°C for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0062] Dissolve 1 g of coconut shell activated carbon and 0.006 g of AIBN in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, blow nitrogen to remove oxygen, and then add 797 μL of 0.1 g / mL chloroplatinic acid hexahydrate ethanol solution, which has been deoxygenated, to the activated carbon / AIBN suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. Dissolve 0.4 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and then slowly add the platinum-loaded activated carbon / AIBN suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid-modified activated carbon-supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, and then pass hydrogen gas, heat it from room temperature to 150°C at a rate of 10°C / min, reduce it with hydrogen for 2 h, switch to nitrogen, and then continue to heat it from 150°C to 500°C at a rate of 10°C / min, and then calcine it with nitrogen for 2 h. Thus, a polymeric ionic liquid-derived carbon-coated metal catalyst is prepared, which is denoted as Pt / C@PIL-150-500.

[0063] Example 4

[0064] Under an ice bath, add 4.0956 g of diethyl sulfate dropwise to 2.5 g of vinyl imidazole, and then stir at 800 rpm for 3 h. Then, add the reaction solution dropwise to an ethanol solution in which 2.2358 g of KOH has been dissolved, and then perform suction filtration after stirring vigorously for 0.5 h to obtain a clear filtrate. Add dilute nitric acid in an amount equivalent to the molar amount of KOH dropwise to the solution, and then perform suction filtration after stirring for 0.5 h to obtain a filtrate. Perform rotary evaporation on the filtrate to obtain a light yellow viscous liquid, wash it with 10 mL of diethyl ether three times, and then perform vacuum drying at 40°C for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0065] Dissolve 1 g of coconut shell activated carbon and 0.006 g of AIBN in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, blow nitrogen to remove oxygen, and then add 797 μL of 0.1 g / mL chloroplatinic acid hexahydrate ethanol solution, which has been deoxygenated, to the activated carbon / AIBN suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. Dissolve 0.8 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and then slowly add the platinum-loaded activated carbon / AIBN suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid-modified activated carbon-supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, and then pass hydrogen gas, heat it from room temperature to 150°C at a rate of 10°C / min, reduce it with hydrogen for 2 h, switch to nitrogen, and then continue to heat it from 150°C to 500°C at a rate of 10°C / min, and then calcine it with nitrogen for 2 h. Thus, a polymeric ionic liquid-derived carbon-coated metal catalyst is prepared, which is denoted as Pt / C@PIL-150-500.

[0066] Example 5

[0067] Under an ice bath, add 4.0956 g of diethyl sulfate dropwise to 2.5 g of vinyl imidazole, and then stir at 800 rpm for 3 h. Then, add the reaction solution dropwise to an ethanol solution in which 2.2358 g of KOH has been dissolved, and then perform suction filtration after stirring vigorously for 0.5 h to obtain a clear filtrate. Add dilute nitric acid in an amount equivalent to the molar amount of KOH dropwise to the solution, perform suction filtration after stirring for 0.5 h, and then perform rotary evaporation on the filtrate to obtain a light yellow viscous liquid. Then, wash the liquid with 10 mL of diethyl ether three times, and then perform vacuum drying at 40°C for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0068] Dissolve 1 g of coconut shell activated carbon and 0.006 g of AIBN in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, blow nitrogen to remove oxygen, and add 797 μL of 0.1 g / mL ethanolic solution of chloroplatinic acid hexahydrate, which has been deoxygenated, dropwise to the activated carbon / AIBN suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. Dissolve 1 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and slowly add the platinum-loaded activated carbon / AIBN suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid modified activated carbon supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, introduce hydrogen, and heat it from room temperature to 150°C at a rate of 10°C / min. Reduce it with hydrogen for 2 h, switch to nitrogen, and continue heating from 150°C to 500°C at a rate of 10°C / min. Calcine it with nitrogen for 2 h. A poly ionic liquid derived carbon coated metal catalyst is prepared, which is denoted as Pt / C@PIL-150-500.

[0069] Comparative Example 2: No free radical initiator is added

[0070] Under an ice bath, add 4.0956 g of diethyl sulfate dropwise to 2.5 g of vinyl imidazole, and stir at 800 rpm for 3 h. Add the reaction solution dropwise to an ethanol solution in which 2.2358 g of KOH is dissolved, and perform suction filtration after stirring vigorously for 0.5 h to obtain a clear filtrate. Add dilute nitric acid in an amount equal to the molar amount of KOH dropwise to the solution, stir for 0.5 h, and then perform suction filtration to obtain a filtrate. Perform rotary evaporation on the filtrate to obtain a light yellow viscous liquid, wash it with 10 mL of diethyl ether three times, and then dry it at 40°C under vacuum for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0071] Dissolve 1 g of coconut shell activated carbon in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, blow nitrogen to remove oxygen, and add 797 μL of 0.1 g / mL ethanolic solution of chloroplatinic acid hexahydrate, which has been deoxygenated, dropwise to the activated carbon suspension under vigorous stirring at 800 rpm to obtain a platinum-loaded activated carbon suspension. Dissolve 0.6 g of 1-ethyl-3-vinylimidazole nitrate in 17 mL of a mixed solution of ethanol and water with a volume ratio of 10:7, and slowly add the platinum-loaded activated carbon suspension after deoxygenation. Polymerize at 65°C for 24 h under nitrogen protection, and then perform suction filtration to obtain a polymeric ionic liquid modified activated carbon supported platinum catalyst precursor. After blowing and drying the precursor at 80°C for 8 h, place it in a tube furnace, introduce hydrogen, and heat it from room temperature to 150°C at a rate of 10°C / min. Reduce it with hydrogen for 2 h, switch to nitrogen, and continue heating from 150°C to 500°C at a rate of 10°C / min. Calcine it with nitrogen for 2 h. A poly ionic liquid derived carbon coated metal catalyst is prepared, which is denoted as Pt / C@IL-150-500.

[0072] TEM images of Pt / C@PIL-150-500 prepared in Example 1, commercial Pt / C (model: T3EQ1, Shaanxi Ruikexin New Material Co., Ltd.) and Pt / C@IL-150-500 prepared in Comparative Example 2 are shown in FIGS. 1-3, respectively. Figure 1c 、 Figure 1a and Figure 1b As shown in FIGS. 1-3, it can be seen that Pt / C is a typical uncoated supported metal catalyst structure, and the metal nanoparticles are obvious. In Pt / C@IL-150-500, no obvious coating layer is seen on the metal nanoparticles. In Pt / C@PIL-150-500, the metal particles are completely coated, indicating that Pt / C@PIL-150-500 is a coated catalyst.

[0073] Comparative Example 3: without hydrogen reduction

[0074] Under ice bath, 4.0956 g diethyl sulfate was added dropwise into 2.5 g vinyl imidazole, and stirred at 800 rpm for 3 h. The reaction solution was added dropwise into an ethanol solution in which 2.2358 g KOH was dissolved. After stirring at high speed for 0.5 h, the clear filtrate was obtained by suction filtration. An amount of dilute nitric acid equivalent to the molar amount of KOH was added dropwise into the solution. After stirring for 0.5 h, the filtrate was obtained by suction filtration. The filtrate was rotary evaporated to obtain a light yellow viscous liquid. The liquid was washed with 10 ml of diethyl ether for 3 times, and dried under vacuum at 40 °C for 24 h to obtain 1-ethyl-3-vinylimidazole nitrate.

[0075] 1 g coconut shell activated carbon and 0.006 g AIBN were dissolved in 17 mL of a mixed solution of ethanol and water in a volume ratio of 10:7. Nitrogen was blown to remove oxygen. 797 μL of 0.1 g / mL chloroplatinic acid hexahydrate ethanol solution was added dropwise into the activated carbon / AIBN suspension under stirring at 800 rpm to obtain a platinum-loaded activated carbon / AIBN suspension. 0.6 g 1-ethyl-3-vinylimidazole nitrate was dissolved in 17 mL of a mixed solution of ethanol and water in a volume ratio of 10:7. After oxygen removal, the platinum-loaded activated carbon / AIBN suspension was slowly added. The polymerization was carried out at 65 °C for 24 h under nitrogen protection. The polymerization ionic liquid modified activated carbon-supported platinum catalyst precursor was obtained by suction filtration. After the precursor was dried at 80 °C by blowing for 8 h, it was placed in a tube furnace and nitrogen was introduced. The temperature was increased from room temperature to 500 °C at a rate of 10 °C / min, and the nitrogen calcination was carried out for 2 h. The poly-ionic liquid derived carbon-coated metal catalyst was prepared, which is denoted as Pt / C@PILs-X-500.

[0076] Application Example 1

[0077] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 1, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and evacuated with nitrogen three times. The air in the reactor was removed and the nitrogen in the reactor was replaced with hydrogen five times. The hydrogen pressure in the reactor was adjusted to 1 MPa. The reactor was heated to 70°C and stirring was started (stirring rate was 750 rpm). The reaction was started. After the reaction was completed, the temperature in the reactor was allowed to decrease to room temperature. 2.04396 g of n-dodecane was added as an internal standard. The sample was taken after stirring for 1 min. The catalyst was filtered and the organic layer was separated. The composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration. The target product was obtained after washing with deionized water and methanol and drying.

[0078] Application Example 2

[0079] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 2, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and evacuated with nitrogen three times. The air in the reactor was removed and the nitrogen in the reactor was replaced with hydrogen five times. The hydrogen pressure in the reactor was adjusted to 1 MPa. The reactor was heated to 70°C and stirring was started (stirring rate was 750 rpm). The reaction was started. After the reaction was completed, the temperature in the reactor was allowed to decrease to room temperature. 2.04396 g of n-dodecane was added as an internal standard. The sample was taken after stirring for 1 min. The catalyst was filtered and the organic layer was separated. The composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration. The target product was obtained after washing with deionized water and methanol and drying.

[0080] Application Example 3

[0081] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 3, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and evacuated with nitrogen three times. The air in the reactor was removed and the nitrogen in the reactor was replaced with hydrogen five times. The hydrogen pressure in the reactor was adjusted to 1 MPa. The reactor was heated to 70°C and stirring was started (stirring rate was 750 rpm). The reaction was started. After the reaction was completed, the temperature in the reactor was allowed to decrease to room temperature. 2.04396 g of n-dodecane was added as an internal standard. The sample was taken after stirring for 1 min. The catalyst was filtered and the organic layer was separated. The composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration. The target product was obtained after washing with deionized water and methanol and drying.

[0082] Application Example 4

[0083] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 4, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and the air inside the reactor was removed by nitrogen three times. The nitrogen inside the reactor was replaced with hydrogen five times, and the hydrogen pressure inside the reactor was adjusted to 1 MPa. The reactor was heated to 70°C, and stirring was started at a stirring rate of 750 rpm. After the reaction was completed, the temperature inside the reactor was allowed to decrease to room temperature, 2.04396 g of n-dodecane was added as an internal standard, and stirring was performed for 1 min. The catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration, and the target product was obtained by washing with deionized water and methanol and drying.

[0084] Application Example 5

[0085] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 5, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and the air inside the reactor was removed by nitrogen three times. The nitrogen inside the reactor was replaced with hydrogen five times, and the hydrogen pressure inside the reactor was adjusted to 1 MPa. The reactor was heated to 70°C, and stirring was started at a stirring rate of 750 rpm. After the reaction was completed, the temperature inside the reactor was allowed to decrease to room temperature, 2.04396 g of n-dodecane was added as an internal standard, and stirring was performed for 1 min. The catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration, and the target product was obtained by washing with deionized water and methanol and drying.

[0086] Table 1 Comparison of catalyst performance of Examples 1-5

[0087]

[0088]

[0089] Application Example 6

[0090] In a 250 mL high-pressure reactor, 0.2 g of the poly-ionic liquid derived carbon-coated metal catalyst prepared in Example 5, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed and the air inside the reactor was removed by nitrogen three times. The nitrogen inside the reactor was replaced with hydrogen five times, and the hydrogen pressure inside the reactor was adjusted to 1 MPa. The reactor was heated to 70°C, and stirring was started at a stirring rate of 750 rpm. After the reaction was completed, the temperature inside the reactor was allowed to decrease to room temperature, 2.04396 g of n-dodecane was added as an internal standard, and stirring was performed for 1 min. The catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration, and the target product was obtained by washing with deionized water and methanol and drying.

[0091] Application Example 7

[0092] In a 250 mL high-pressure reactor, 0.2 g of the polyionic liquid derived carbon-coated metal catalyst prepared in Comparative Example 3, 9.42 g of o-chloronitrobenzene, and 80 mL of ethanol were sequentially added. The reactor was sealed, purged with nitrogen three times, and the air inside the reactor was replaced with hydrogen five times. The hydrogen pressure in the reactor was adjusted to 1 MPa, and then the reactor was heated to 70°C and stirred (stirring rate was 750 rpm) to start the reaction. After the reaction was completed, the temperature in the reactor was reduced to room temperature, 2.04396 g of n-dodecane was added as an internal standard, and the mixture was stirred for 1 min. The catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance gas chromatography. The solvent was removed by vacuum filtration, washed with deionized water and methanol, dried, and the target product was obtained.

[0093] Table 2 Comparison of catalyst performance of Examples 1, 6, and 7

[0094]

[0095] Comparing Example 1 and Comparative Example 2 shows that using AIBN as a free radical initiator during catalyst preparation is beneficial for the in-situ polymerization of 1-ethyl-3-vinylimidazole nitrate on the surface of metal particles to form a polyionic liquid and achieve full coating of the metal particles, thereby improving the catalytic hydrogenation performance of the catalyst. Comparing Example 1 and Comparative Example 3 shows that Pt is converted to Pt after hydrogen reduction, greatly improving the activity of the catalyst. 2+ and Pt 4+ is converted to Pt 0 , greatly improving the activity of the catalyst.

[0096] Application Example 8

[0097] The experimental conditions were the same as in Application Example 1, and the filtered catalyst was repeatedly used for the next reaction. The composition of the hydrogenation product in the filtrate obtained from each reuse experiment was analyzed by high-performance gas chromatography, and the results are shown in Table 2:

[0098] Table 3 Catalyst reuse results of Example 1

[0099]

[0100] *The reaction conditions were the same as in Application Example 1

[0101] Application Example 9

[0102] The experimental conditions were the same as in Application Example 3, and the filtered catalyst was repeatedly used for the next reaction. The composition of the hydrogenation product in the filtrate obtained from each reuse experiment was analyzed by high-performance gas chromatography, and the results are shown in Table 3:

[0103] Table 4 Catalyst Comparative Example 3 Application Results

[0104]

[0105] * Reaction conditions were the same as in Application Example 3.

Claims

1. A method for preparing a poly ionic liquid derived carbon-coated metal catalyst, characterized in that: The preparation method is carried out according to the following steps: Step one: dissolving activated carbon and azobisisobutyronitrile (AIBN) in a mixed solution of ethanol and water, blowing nitrogen to remove oxygen, to obtain activated carbon / AIBN suspension; Step two: under vigorous stirring, adding dropwise ethanol solution of chloroplatinic acid hexahydrate with removed oxygen into the suspension obtained in step one, to obtain activated carbon / AIBN suspension loaded with platinum; Step three: dissolving 1-ethyl-3-vinylimidazole nitrate in a mixed solution of ethanol and water, after removing oxygen, slowly adding the activated carbon / AIBN suspension loaded with platinum obtained in step two, under nitrogen protection, stirring at 60-70℃ for 12-24h, and then filtering to obtain a poly ionic liquid modified activated carbon supported platinum catalyst precursor; the weight ratio of activated carbon to 1-ethyl-3-vinylimidazole nitrate in the activated carbon / AIBN suspension loaded with platinum is 1:0.2-1; Step four: drying the poly ionic liquid modified activated carbon supported platinum catalyst precursor obtained in step three; Step five: first calcining the product obtained in step four under hydrogen atmosphere, and then calcining under inert gas atmosphere, to obtain a poly ionic liquid derived carbon coated metal catalyst.

2. The preparation method according to claim 1, wherein: In step one, the mass ratio of activated carbon to AIBN is 1:0.005-1.

3. The production method according to claim 2, characterized by: In step one, the mass ratio of activated carbon to AIBN is 1:0.005-0.

01.

4. The production method according to claim 1, wherein: In step one or step three, the volume ratio of ethanol to water in the mixed solution of ethanol and water is 10:6-10.

5. The production method according to claim 1, wherein: In step two, the concentration of the ethanol solution of chloroplatinic acid hexahydrate is 0.05-0.15g / mL.

6. The production method according to claim 1, wherein: In step two, the mass fraction ratio of platinum contained in the ethanol solution of chloroplatinic acid hexahydrate to activated carbon is 2.5-3.5%:

1.

7. The production method according to claim 1, wherein: In step three, the weight ratio of activated carbon to 1-ethyl-3-vinylimidazole nitrate is 1:0.

6.

8. The production method according to claim 1, wherein: In step four, the drying conditions are: temperature of 60-80℃, and time of 8-12h.

9. The production method according to claim 1, wherein: In step five, the heating rate is 10℃ / min, the hydrogen reduction conditions are 100-200℃ for 2h, the inert gas is N2, and the N2 calcination conditions are 450-500℃ for 2h.

10. A poly ionic liquid derived carbon coated metal catalyst prepared by the preparation method according to any one of claims 1-9.

11. Application of the poly ionic liquid derived carbon coated metal catalyst according to claim 10 in catalytic hydrogenation reaction of chloronitrobenzene.

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