Hydrogenation catalyst, method for preparing the same, and use thereof

Abstract

The application discloses a hydrogenation catalyst and a preparation method and application thereof. The catalyst comprises a carrier and active components and auxiliary metals attached to the carrier. The carrier is hollow glass beads modified by a polymeric amine and an alkali metal fluoride. The auxiliary metals are selected from one or more of Li, Na, Cs, Co, Cr, Ir, Mn and Sr. The catalyst prepared by the application can catalyze the hydrogenation of dinitrotoluene to toluenediamine at a high conversion rate and product selectivity at a high reaction temperature. The catalyst has stable performance, is not easy to be caked, is resistant to wear and tear, and has a long service life. The catalyst can significantly improve production efficiency, reduce production cost, and is favorable for industrial application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and in particular, relates to a hydrogenation catalyst and a preparation method, and application thereof in the production of toluenediamine from dinitrotoluene by hydrogenation. BACKGROUND

[0002] Toluenediamine (TDA, also known as diaminotoluene) is an important raw material for the production of toluene diisocyanate (TDI) and is widely used in dyes, pharmaceutical intermediates and other organic synthesis intermediates. Toluene diisocyanate, which is prepared from toluenediamine, is one of the important raw materials for the production of polyurethane. How to efficiently and economically prepare toluenediamine is a research hotspot at home and abroad.

[0003] Currently, toluenediamine is generally prepared by liquid-phase catalytic hydrogenation of dinitrotoluene (DNT) in the industry. There are mainly two types of hydrogenation catalysts used in the hydrogenation reaction in the industry, namely noble metal system catalysts and nickel-based catalysts. The main active components of noble metal catalysts are palladium and platinum noble metals. Such catalysts have mild reaction conditions and high catalytic activity, but they have high tar by-products and low toluenediamine yield. In addition, the noble metals supported on the carrier are prone to loss, and the application cost is high. For example, the carbon black catalyst containing palladium, platinum and iron disclosed in patent CN105435808A. Nickel-based catalysts mainly include supported nickel catalysts and skeletal nickel catalysts. Such catalysts have high catalytic activity and good selectivity, but the reaction conditions are high temperature and high pressure. In addition, such catalysts have poor heat resistance and are prone to local overheating and caking, which reduces the service life and production capacity of the catalyst.

[0004] Patent CN101252987A discloses a method for preparing toluenediamine by hydrogenation of dinitrotoluene. A catalyst containing platinum, nickel and other metals is used to hydrogenate dinitrotoluene at a reaction temperature not lower than 160℃. The reaction heat is used to generate steam. The excessively high reaction temperature inevitably leads to an increase in side reactions and is prone to local overheating and caking of the catalyst, which increases the cost of the catalyst.

[0005] In addition, tar is produced during the production of toluenediamine, mainly including various amino and methyl-substituted diphenylamine, diphenylhydrazine and phenazine, etc. The existing treatment method is incineration, which causes air pollution. Patent CN109790104A uses a heterogeneous catalyst to react with TDA tar under hydrogenation conditions and hydrogen gas, so that the TDA tar can be hydrogenated to form valuable products, thereby removing TDA from the TDA tar. However, the process flow is complex and difficult to be applied in industrialization. SUMMARY

[0006] In order to solve the problems in the prior art, the application provides a hydrogenation catalyst, a preparation method and application thereof, the catalyst prepared by the method can obtain high raw material conversion rate and product selectivity at high reaction temperature, and the catalyst has stable performance, is not easy to be caked, is resistant to wear and tear, and has long service life.

[0007] In order to achieve the above object, the application adopts the technical scheme as follows:

[0008] In one aspect of the application, a hydrogenation catalyst is provided, the catalyst comprising a carrier and active components and an auxiliary agent attached to the carrier.

[0009] The active components comprise one or more than two of Ni, Pd, Pt, Rh, Ra and Ru; preferably, the active components are Ni; further, the content of the active components is 0.05-50wt% of the mass of the carrier, preferably 0.1-35wt%, more preferably 0.5-15wt%.

[0010] The auxiliary agent is selected from one or more of the group consisting of Li, Na, Cs, Co, Cr, Ir, Mn and Sr, preferably one or more of Sr, Ir, Cs and Cr; further, the content of the auxiliary agent is 0.01-0.5wt% of the mass of the carrier, preferably 0.05-0.1wt%.

[0011] The carrier is a hollow glass microsphere modified on the surface; preferably, the carrier is a hollow glass microsphere modified by polymeric amine and alkali metal fluoride.

[0012] In the application, the mass percentage content refers to the mass of the metal element represented by the active component in the compound containing the active component / auxiliary agent, for example, if the nickel element exists in the form of chloride (nickel chloride), the mass percentage content of nickel is calculated based on the mass of the "nickel element", for example, if the nickel element exists in the form of pure metal, the mass percentage content of nickel is calculated based on the mass of the pure metal.

[0013] In another aspect of the application, a preparation method of the catalyst is provided, comprising the following steps:

[0014] (a) preparing a hollow glass microsphere carrier modified on the surface;

[0015] (b) mixing the carrier prepared in step (a), a soluble metal salt of the active component and a soluble metal salt of the auxiliary agent in aqueous solution, adding alkali to adjust pH, and stirring and impregnating;

[0016] (c) adding a reducing agent to reduce, ultrasonically standing, and then washing with water and drying to obtain the catalyst.

[0017] In the present application, the preparation method of the hollow glass microsphere carrier modified on the surface in step (a) comprises:

[0018] S1: toluene diamine tar is mixed with an activator, and polymerization is carried out in an oxygen atmosphere to obtain a polymerization liquid, and then the polymerization liquid is activated by an alkali solution in an inert gas atmosphere to obtain a polymer amine modified liquid;

[0019] S2: hollow glass microspheres and sodium tripolyphosphate solution are added to the polymer amine modified liquid obtained in step S1, and stirring and mixing are carried out, and then washing with deionized water until neutral, standing, filtering, drying, calcining, and cooling to room temperature are carried out, and then grinding is carried out to obtain a catalyst carrier;

[0020] S3: alkali metal fluoride is dissolved in water, and the catalyst carrier prepared in S2 is added and mixed and stirred, and then washing with deionized water until neutral, filtering, drying, and calcining are carried out to obtain a hollow glass microsphere carrier modified on the surface;

[0021] In step S1 of the present application, the toluene diamine tar refers to tar produced in the process of producing TDA by liquid phase catalytic hydrogenation of DNT, which is mainly a mixture of toluene diamine and heavy components, wherein the content of toluene diamine is 10-50wt%, and the heavy components are various amino and methyl-substituted diphenylamine, diphenylhydrazine, and phenazine, etc.;

[0022] The activator is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide;

[0023] The mass ratio of toluene diamine tar to activator is 1:(0.1-5), preferably 1:(0.1-2); further, the activator is configured as an aqueous solution for use, and the mass concentration of the activator solution is 10-30wt%;

[0024] The polymerization reaction temperature is 120-150℃, and the polymerization reaction time is 60-120min.

[0025] In step S1 of the present application, when the alkali solution is used for activation treatment, the inert gas atmosphere is one or a combination of two of nitrogen, helium, neon, argon, krypton, and xenon, preferably one or two of nitrogen, helium, and argon;

[0026] The alkali solution comprises at least one of sodium hydroxide solution, potassium hydroxide solution, urea solution, and hydrogenation wastewater; further, the alkali solution is preferably hydrogenation wastewater, which refers to wastewater removed in the toluene diamine preparation process, mainly water and organic matter (methylcyclohexanol, aniline, toluidine, etc.), wherein the concentration of the organic matter is 0.1-3wt%, preferably 1-3wt%; further, when sodium hydroxide solution, potassium hydroxide solution, and urea solution are used as the alkali solution for activation treatment, the concentration is 10-20wt%.

[0027] Further, the mass ratio of the alkali solution to the polymerization solution is 1:(0.2-10); the alkali activation time is 0.5-5h, and the activation temperature is 300-700℃.

[0028] In the step S2, the particle size of the hollow glass microsphere is 10-120um; the mass ratio of the hollow glass microsphere to the polyamine modification solution is 1:(1-10); and the amount of the sodium tripolyphosphate is (0.01-0.2g) / (g of the hollow glass microsphere).

[0029] In the step S2, the stirring speed is 400-600rpm, and the stirring time is 10-30min; the drying temperature is 100-150℃, and the drying time is 2-3h; the calcination temperature is 400-550℃, and the calcination time is 4-6h; and the average particle size of the ground catalyst carrier is 10-80um.

[0030] In the step S3, the alkali metal fluoride is selected from one or more of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, and cesium fluoride; the mass of the alkali metal fluoride is 10-30% of the mass of the carrier, preferably 10-20%; and the mass concentration of the alkali metal fluoride solution is 0.1-2wt%.

[0031] In the step S3, the stirring speed is 400-600rpm, and the stirring time is 10-30min; the drying temperature is 120-200℃, and the drying time is 0.5-2h; the calcination temperature is 300-500℃, and the calcination time is 4-7h.

[0032] In the step (b), the soluble metal salt of the active component can be selected from one or more of nitrate, acetate, and chloride.

[0033] The soluble metal salt of the auxiliary in the step (b) includes one or more of lithium salt, sodium salt, cesium salt, cobalt salt, chromium salt, iridium salt, manganese salt, and strontium salt.

[0034] Further, the strontium salt includes one or more of halide salt, nitrate, and bromate.

[0035] The iridium salt includes one or more of nitrate, chloride, and hydrate thereof.

[0036] The cesium salt includes one or more of nitrate, carbonate, sulfate, and chloride.

[0037] The chromium salt includes one or more of nitrate, acetate, sulfate, and chloride.

[0038] The base in step (b) is selected from one or more of potassium hydroxide, sodium hydroxide, ammonia water; the base is used in a solution with a concentration of 3-20 wt%; the pH value is adjusted to 8-12, preferably 9-11; the impregnation temperature is 15-30℃, preferably 20-25℃; the impregnation time is 2-6h, preferably 4-6h; the stirring speed is 200-400rpm, preferably 200-300rpm.

[0039] The reducing agent in step (c) is one of hydrogen, formaldehyde, hydrazine hydrate, sodium sulfite, preferably hydrazine hydrate; preferably, the reduction time is 2-5h, so that the metal salt is reduced to metal.

[0040] The application also simultaneously provides the use of the above-mentioned catalyst in the catalytic hydrogenation of aromatic nitro compounds to prepare aromatic amines, especially in the synthesis of toluene diamine by hydrogenation of dinitrotoluene.

[0041] Preferably, the method is continuously or intermittently carried out in a conventional reactor with conventional process parameters such as pressure and temperature, using the catalyst, taking dinitrotoluene as the raw material, and hydrogenating under hydrogen to prepare toluene diamine. Preferably, the reaction pressure is 5-70 barg, more preferably 10-40 barg, and particularly preferably 20-25 barg; the reaction temperature is 100-300℃, more preferably 120-270℃, and particularly preferably 150-250℃.

[0042] Compared with the prior art, the application has the following advantages:

[0043] 1. The catalyst uses modified hollow glass microbeads as the catalyst carrier, which has the advantages of high mechanical strength, good compression resistance, excellent dispersibility, strong fluidity, good stability, and good thermal conductivity. The prepared catalyst has the advantages of high activity, high selectivity, good dispersibility, long service life, wear resistance, and non-caking under high temperature and high pressure.

[0044] 2. The polymerized amine modified liquid is used to modify the surface of the hollow glass microbeads by taking advantage of the polymerization characteristics of organic amine substances under high-temperature oxygen atmosphere. A large amount of nitrogen-doped carbon is loaded on the surface of the hollow glass microbead skeleton, which can significantly increase the surface roughness and specific surface area of the carrier, facilitate the subsequent loading of active metals and auxiliary metals on the surface of the carrier, and strengthen the thermal conductivity of the carrier, thereby improving the anti-sintering performance of the catalyst under high temperature. The nitrogen element on the surface of the carrier has a synergistic effect with the active metals on the hydrogenation catalyst, thereby strengthening the performance of the hydrogenation catalyst. After the carrier is modified by alkali metal fluoride, the number of basic sites on the surface of the carrier is increased, which is beneficial to the desorption of the hydrogenation reaction products and reduces the generation of over-hydrogenated by-products.

[0045] 3. The addition of the auxiliary metal improves the dispersion of the active metal on the surface of the catalyst, reduces the consumption of the active metal during the preparation of the catalyst, reduces the production cost of the catalyst, and the addition of the auxiliary metal can also strengthen the selectivity of the catalyst and reduce the generation of by-products. DETAILED DESCRIPTION

[0046] To further disclose but not limit the present application, the present application is further described in detail below in combination with examples.

[0047] The chemicals used in the hydrogenation experiment are all from the TDI production device of Wanhua Chemical, the TDA tar is from the toluene diamine production device of Wanhua Chemical, and the composition includes C 71-75wt%, H 3-5wt%, and N 20-26wt%; the hydrogenated wastewater is obtained after further concentration of the wastewater generated from the reaction unit of the toluene diamine production device of Wanhua Chemical, and the composition includes methylcyclohexylamine 0.13-0.17wt%, methylcyclohexanol 1-1.7wt%, methylcyclohexanone 0.33-0.35wt%, aniline 0.02-0.04wt%, and o-toluidine 0.15-0.2wt%.

[0048] Other materials such as hollow glass microspheres, sodium tripolyphosphate, strontium salt, iridium salt, cesium salt, and chromium salt are all purchased through commercial channels unless otherwise specified.

[0049] Catalyst characterization: the specific surface area is measured by the NOVA4000 and SI-MP full-automatic physical adsorption instrument of the American CANTA Company according to the GB / T5816-1995 standard and the ISO92277 standard; the particle size of the catalyst is measured by the HELOS1BF particle size instrument of the German new Patek Company.

[0050] Example 1

[0051] Preparation of the carrier:

[0052] 1) 100g of TDA tar with a toluene diamine content of 15wt% is ground and treated, and then 25wt% of potassium hydroxide solution is mixed with the tar powder at a mass ratio of toluene diamine tar: potassium hydroxide of 1:0.75 under a stirring speed of 300r / min for 30min, and then the mixed product is kept at 140℃ under an oxygen atmosphere for 110min, and then 80g of hydrogenated wastewater with an organic matter concentration of 2wt% is added under a nitrogen atmosphere for 3h of alkali activation treatment at an activation temperature of 400℃, to obtain a polymer amine modified solution.

[0053] 2) Add 80 g hollow glass microspheres with an average particle size of 15 um and 25 g sodium tripolyphosphate solution with a concentration of 15 wt% into the polymeric amine modified solution, mix for 30 min at a stirring speed of 500 r / min, wash with deionized water until neutral, filter after standing, dry at 140 °C for 2.5 h, calcine at 500 °C for 6 h, and grind into powder after cooling to room temperature.

[0054] 3) Weigh 5 g potassium fluoride into 500 g deionized water to prepare an aqueous solution, add 50 g of the powder prepared in step 2), mix at a stirring speed of 500 rpm for 30 min, filter after washing with deionized water until neutral, dry at 200 °C for 1.5 h, and obtain the modified hollow glass microsphere carrier after calcining at 500 °C for 6 h. The average particle size of the carrier is 17 um, and the specific surface area of the carrier is 420 m 2 / g.

[0055] Catalyst preparation:

[0056] Weigh 16.5 g of nickel chloride and 0.15 g of strontium nitrate into 200 g of deionized water, and dissolve the metal salts under stirring until they are fully dissolved. Then add 30 g of the prepared catalyst carrier to the mixture, and slowly add 15 wt% ammonia water to the mixture to adjust the pH to 10. Stir and immerse the mixture at 25 °C for 4 h. Then slowly add 200 g of a 50 wt% hydrazine hydrate solution to the mixture, and stir for 4 h of reduction reaction. After ultrasonic standing for 1 h, separate the solid and liquid, wash with deionized water until neutral, and dry to obtain catalyst A. The average particle size of catalyst A is 17.3 um.

[0057] Hydrogenation of dinitrotoluene:

[0058] In a 1 L continuous full-mix tank reactor, add 200 g of solvent (H2O 38.7 wt%, TDA 61.3 wt%) as the reaction bottom liquid, and add 4 g of catalyst A prepared according to the above steps. Replace the residual air in the reactor with high-purity nitrogen for 3 times at room temperature, and then replace it with high-purity hydrogen for 4 times until the hydrogen concentration in the replacement gas is greater than 99.9 vol%. After passing the replacement, pressurize the reactor to 21 barg, control the stirring speed to 1100 rpm, and heat the reactor to 170 °C. Control the mass space velocity of dinitrotoluene to be 5.7 kg DNT / (kg catalyst*h), control the mass ratio of hydrogen to dinitrotoluene to be 8:1, and control the reaction liquid withdrawal rate to maintain the liquid holdup in the reactor at the initial value. Start the reaction. After 12 h of reaction, sample and test, the conversion rate of dinitrotoluene is 99.99%, and the selectivity of TDA is 99.23%.

[0059] After continuing the reaction to 120h, sampling and testing, the conversion rate of dinitrotoluene was 99.98%, the selectivity of TDA was 99.17%, the catalyst in the reactor had no caking phenomenon and was well dispersed, and the average particle size of the catalyst was 17.1um.

[0060] Example 2

[0061] Preparation of the carrier:

[0062] 1) 100g of TDA tar with a toluene diamine content of 20wt% was ground and treated, and 25wt% of a sodium hydroxide solution was mixed with the tar at a toluene diamine tar:sodium hydroxide mass ratio of 1:0.5 under stirring at a speed of 300r / min for 30min. The mixed product was kept at 150℃ under an oxygen atmosphere for 120min, and then 60g of hydrogenated wastewater alkali with an organic matter concentration of 3wt% was added under a nitrogen atmosphere for 4h of activation treatment at a temperature of 450℃, to obtain a polyamine modified liquid.

[0063] 2) 80g of hollow glass microbeads with an average particle size of 18um and 30g of a sodium tripolyphosphate solution with a concentration of 15wt% were added to the polyamine modified liquid, and stirred at a speed of 600r / min for 30min. After washing with deionized water until neutral, standing, and filtration, the product was dried at 140℃ for 3h and calcined at 450℃ for 6h. After cooling to room temperature, the product was ground into powder.

[0064] 3) 5g of sodium fluoride was added to 500g of deionized water to prepare an aqueous solution, and 50g of the powder prepared in step 2) was added. After stirring and mixing at a speed of 500rpm for 30min, the product was washed with deionized water until neutral, filtered, dried at 200℃ for 2h, and calcined at 500℃ for 7h to obtain modified hollow glass microbead carrier. After testing, the average particle size of the carrier was 19.3um, and the specific surface area of the carrier was 400m 2 / g.

[0065] Preparation of the catalyst:

[0066] 20.5g of nickel nitrate hexahydrate and 0.1g of iridium potassium chlorate were dissolved in 200g of deionized water under stirring until the metal salts were fully dissolved. Then, 30g of the prepared catalyst carrier was added, and 15wt% ammonia water was slowly added to the mixture to adjust the pH to 9. The mixture was stirred and impregnated at 20℃ for 5h. Subsequently, 150g of a hydrazine hydrate solution with a concentration of 45wt% was slowly added, and the mixture was stirred for 5h of reduction reaction. After standing for 2h under ultrasonic, the solid and liquid were separated, washed with deionized water until neutral, and dried to obtain catalyst B. After testing, the average particle size of catalyst B was 19.5um.

[0067] Hydrogenation of dinitrotoluene:

[0068] In a 1 L continuous stirred tank reactor, 200 g of solvent (H2O 38.3 wt%, TDA 61.7 wt%) was added as the reaction bottom liquid, and 4 g of catalyst B prepared according to the above steps was added. The residual air in the reactor was removed by replacing it with high-purity nitrogen three times at room temperature, and then replaced with high-purity hydrogen four times until the hydrogen concentration in the replacement gas was greater than 99.9 vol%. After passing, the reactor was pressurized to 22 barg, the stirring speed was controlled at 1100 rpm, and the reactor was heated to 175°C. The mass space velocity of dinitrotoluene was 5.7 kg DNT / (kg catalyst*h), the mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid was collected at a rate to maintain the initial liquid holdup in the reactor. The reaction was started. After 12 h of reaction, sampling and testing showed that the conversion rate of dinitrotoluene was 99.99%, and the selectivity of TDA was 99.33%.

[0069] After continuing the reaction to 120 h, sampling and testing showed that the conversion rate of dinitrotoluene was 99.99%, the selectivity of TDA was 99.16%, and the catalyst in the reactor was well dispersed without caking, with an average particle size of 19.2 um.

[0070] Example 3

[0071] Preparation of the carrier:

[0072] 1) 100 g of TDA tar with a toluene diamine content of 30 wt% was ground and treated, and 30 wt% cesium hydroxide solution was mixed with the tar powder at a mass ratio of toluene diamine tar to cesium hydroxide of 1:1.2 under stirring at a speed of 300 r / min for 30 min. The mixture was then kept at 130°C in an oxygen atmosphere for 120 min, and then 100 g of a 15% urea solution was added under a nitrogen atmosphere for alkaline activation for 5 h at a temperature of 500°C to obtain a polyamine modified liquid.

[0073] 2) 80 g of hollow glass microbeads with an average particle size of 16 um and 30 g of a 20 wt% sodium tripolyphosphate solution were added to the above polyamine modified liquid, mixed at a stirring speed of 600 r / min for 30 min, washed with deionized water until neutral, and then filtered and dried at 150°C for 3 h and calcined at 500°C for 5.5 h. After cooling to room temperature, the product was ground into powder.

[0074] 3) 7 g of sodium fluoride was weighed into 500 g of deionized water to prepare an aqueous solution, and 50 g of the powder prepared in step 2) was added. The mixture was stirred at a speed of 600 rpm for 30 min, washed with deionized water until neutral, and then filtered and dried at 200°C for 2 h and calcined at 500°C for 6 h to obtain modified hollow glass microbead carrier. The average particle size of the carrier was 16.7 um, and the specific surface area of the carrier was 430 m 2 / g.

[0075] Catalyst preparation:

[0076] Weigh 12.1 g of nickel acetate, 0.15 g of cesium sulfate into 200 g of deionized water and fully dissolve the metal salt under stirring, then add 30 g of the prepared catalyst carrier to the mixture, slowly add 20 wt% ammonia water to the mixture to adjust the pH to 10, and stir the mixture at 25°C for 5 h. Then slowly add 300 g of 30 wt% hydrazine hydrate solution to the mixture and stir for 5 h. After ultrasonic standing for 2 h, separate the solid and liquid, wash with deionized water until neutral, and dry to obtain catalyst C. The average particle size of catalyst C is 17.1 um.

[0077] Hydrogenation of dinitrotoluene:

[0078] In a 1 L continuous full-mix tank reactor, 200 g of solvent (H2O 38.8 wt%, TDA 61.2 wt%) is added as the reaction bottom liquid, and 4 g of catalyst C prepared according to the above steps is added. The residual air in the reactor is removed by replacing it with high-purity nitrogen for 3 times at room temperature, and then replaced with high-purity hydrogen for 4 times until the hydrogen concentration in the replacement gas is greater than 99.9 vol%. After the replacement is qualified, the reactor is pressurized to 22 barg, the stirring speed is controlled at 1100 rpm, and the reactor is heated to 185°C. The mass space velocity of dinitrotoluene is 5.7 kg DNT / (kg catalyst*h), the mass ratio of hydrogen to dinitrotoluene is controlled at 8:1, and the reaction liquid withdrawal rate is controlled to maintain the initial liquid holdup in the reactor. The reaction is started. After 12 h of reaction, sampling test shows that the conversion rate of dinitrotoluene is 99.99%, and the selectivity of TDA is 99.12%.

[0079] After continuing the reaction to 120 h, sampling test shows that the conversion rate of dinitrotoluene is 99.97%, the selectivity of TDA is 99.03%, and the catalyst in the reactor is well dispersed without caking, with an average particle size of 17 um.

[0080] Example 4

[0081] Carrier preparation:

[0082] 1) Weigh 100 g of TDA tar with a toluene diamine content of 40 wt%, grind the tar powder, and mix 30 wt% lithium hydroxide at a toluene diamine tar: lithium hydroxide mass ratio of 1:1.5 under a stirring speed of 300 r / min for 30 min. Then, the mixed product is kept at 140°C under an oxygen atmosphere for 100 min, and then an organic matter concentration of 2.5 wt% hydrogenated wastewater alkali is added under a nitrogen atmosphere for 4 h of activation treatment at an activation temperature of 600°C, to obtain a polymeric amine modified liquid.

[0083] 2) Add 80g of hollow glass microspheres with an average particle size of 17um and 35g of sodium tripolyphosphate solution with a concentration of 25wt% to the above-mentioned polyamine modified solution. Mix at a stirring speed of 600r / min for 30min, wash with deionized water until neutral, let stand and filter, dry at 140℃ for 3h, calcine at 550℃ for 5h, cool to room temperature and grind into powder.

[0084] 3) Weigh 7g of potassium fluoride and add it to 500g of deionized water to prepare an aqueous solution. Add 50g of the powder prepared in step 2), stir and mix at 600rpm for 30min, wash with deionized water until neutral, filter, dry at 180℃ for 2h, and calcine at 500℃ for 6.5h to obtain the modified hollow glass microsphere carrier. The average particle size of the carrier is 17.4µm, and the specific surface area of ​​the carrier is 440m². 2 / g.

[0085] Catalyst preparation:

[0086] 14.5 g of nickel acetate tetrahydrate and 0.08 g of chromium chloride were dissolved in 200 g of deionized water and stirred until the metal salts were fully dissolved. Then, 30 g of the prepared catalyst support was added, and 20 wt% ammonia was slowly added dropwise to adjust the pH to 9. The mixture was stirred and impregnated at 20 °C for 6 h. Subsequently, 150 g of 45 wt% hydrazine hydrate solution was slowly added and stirred for reduction reaction for 4 h. After ultrasonic settling for 1 h, the solid and liquid were separated, washed with deionized water until neutral, and dried to obtain catalyst D. The average particle size of catalyst D was measured to be 17.7 μm.

[0087] Hydrogenation of dinitrotoluene:

[0088] In a 1L continuous stirred tank reactor, 200g of solvent (38.9wt% H2O, 61.1wt% TDA) was added as the reaction base liquid, along with 4g of catalyst D prepared according to the above steps. At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas was greater than 99.9 vol%. After successful purging, the reactor was pressurized to 25 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 185℃. The mass hourly space velocity (WHSV) of dinitrotoluene was 5.7 kg DNT / (kg catalyst * h). The mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing, showing a dinitrotoluene conversion of 99.99% and a TDA selectivity of 99.23%.

[0089] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 99.99%, the TDA selectivity was 99.19%, there was no agglomeration of the catalyst in the reactor, the dispersion was good, and the average particle size of the catalyst was 17.4 μm.

[0090] Example 5

[0091] Carrier preparation:

[0092] 1) Weigh 100g of TDA tar with a toluene diamine content of 25wt%, grind the tar powder obtained after grinding, and mix it with 25wt% sodium hydroxide solution at a mass ratio of toluene diamine tar to sodium hydroxide of 1:1. Stir at 300r / min for 30min, and keep the uniformly mixed product at 130℃ and oxygen atmosphere for 120min. Then add 60g of hydrogenated wastewater with an organic matter concentration of 3wt% under nitrogen atmosphere for alkaline activation treatment for 4h at an activation temperature of 550℃ to obtain the polyamine modified solution.

[0093] 2) Add 80g of hollow glass microspheres with an average particle size of 15um and 35g of sodium tripolyphosphate solution with a concentration of 25wt% to the above-mentioned polyamine modified solution. Mix at a stirring speed of 600r / min for 30min, wash with deionized water until neutral, let stand and filter, dry at 150℃ for 3h, calcine at 550℃ for 5.5h, cool to room temperature and grind into powder.

[0094] 3) Weigh 7g of sodium fluoride and add it to 500g of deionized water to prepare an aqueous solution. Add 50g of the powder prepared in step 2), stir and mix at 600rpm for 30min, wash with deionized water until neutral, filter, dry at 200℃ for 2h, and calcine at 500℃ for 6.5h to obtain the modified hollow glass microsphere carrier. The average particle size of the carrier is 15.4µm, and the specific surface area of ​​the carrier is 450m². 2 / g.

[0095] Catalyst preparation:

[0096] 3.5 g of radium chloride and 0.14 g of strontium nitrate were dissolved in 200 g of deionized water under stirring until the metal salts were fully dissolved. Then, 30 g of the prepared catalyst support was added, and 15 wt% ammonia solution was slowly added dropwise to adjust the pH to 9. The mixture was stirred and impregnated at 25 °C for 5 h. Subsequently, 170 g of 40 wt% hydrazine hydrate solution was slowly added, and the reaction was stirred and reduced for 4 h. After ultrasonic settling for 1 h, the solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain catalyst E. The average particle size of catalyst D was measured to be 15.5 μm.

[0097] Hydrogenation of dinitrotoluene:

[0098] In a 1L continuous stirred tank reactor, 200g of solvent (39.2wt% H₂O, 60.8wt% TDA) was added as the reaction base liquid, along with 4g of catalyst E prepared according to the above steps. At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas was greater than 99.9 vol%. After successful purging, the reactor was pressurized to 24 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 180℃. The mass hourly space velocity (WHSV) of dinitrotoluene was 5.7 kg DNT / (kg catalyst*h). The mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing, showing a dinitrotoluene conversion of 99.99% and a TDA selectivity of 99.33%.

[0099] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 99.99%, the TDA selectivity was 99.29%, there was no agglomeration of the catalyst in the reactor, the dispersion was good, and the average particle size of the catalyst was 15.2 μm.

[0100] Comparative Example 1

[0101] Catalyst preparation:

[0102] The steps of Example 1 were repeated, except that the same mass of unmodified hollow glass microspheres with an average particle size of 15 μm were used as the catalyst support. The average particle size of catalyst F was tested to be 15.2 μm.

[0103] Hydrogenation of dinitrotoluene:

[0104] In a 1L continuous stirred tank reactor, 200g of solvent (39.1wt% H₂O, 60.9% wt% TDA) was added as the reaction base liquid, along with 4g of catalyst F prepared according to the above steps. At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas was greater than 99.9 vol%. After successful purging, the reactor was pressurized to 21 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 170℃. The mass hourly space velocity (WHSV) of dinitrotoluene was 5.7 kg DNT / (kg catalyst * h). The mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing. The conversion rate of dinitrotoluene was 76.87%, and the TDA selectivity was 85.53%.

[0105] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 71.37%, the TDA selectivity was 79.65%, there was no agglomeration of the catalyst in the reactor, the dispersion was good, and the average particle size of the catalyst was 14.9 μm.

[0106] Comparative Example 2

[0107] Catalyst preparation:

[0108] The steps of Example 1 were repeated, except that the support was replaced with an equal mass of activated carbon with an average particle size of 18 μm as the catalyst support. The average particle size of catalyst G was tested to be 18.2 μm.

[0109] Hydrogenation of dinitrotoluene:

[0110] In a 1L continuous stirred tank reactor, 200g of solvent (38.4wt% H2O, 61.6% wt% TDA) was added as the reaction base liquid, along with 4g of catalyst G prepared according to the above steps. At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas was greater than 99.9 vol%. After successful purging, the reactor was pressurized to 21 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 170℃. The mass hourly space velocity (WHSV) of dinitrotoluene was 5.7 kg DNT / (kg catalyst * h). The mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing. The conversion rate of dinitrotoluene was 93.54%, and the TDA selectivity was 89.23%.

[0111] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 83.37%, the TDA selectivity was 79.27%, and the catalyst agglomeration in the reactor was obvious, with an average particle size of 13.2 μm.

[0112] Comparative Example 3

[0113] Catalyst preparation:

[0114] The steps of Example 1 were repeated, except that the metal additive strontium was not added. The average particle size of catalyst H was tested to be 17.2 μm.

[0115] Hydrogenation of dinitrotoluene:

[0116] In a 1L continuous stirred tank reactor, 200g of solvent (38.2wt% H₂O, 61.8wt% TDA) was added as the reaction base liquid, along with 4g of catalyst H prepared according to the above steps. At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas exceeded 99.9 vol%. After successful purging, the reactor was pressurized to 21 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 170℃. The mass hourly space velocity (WHSV) of dinitrotoluene was 5.7 kg DNT / (kg catalyst * h). The mass ratio of hydrogen to dinitrotoluene was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing, showing a dinitrotoluene conversion of 98.84% and a TDA selectivity of 97.23%.

[0117] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 98.57%, the TDA selectivity was 96.78%, there was no agglomeration of the catalyst in the reactor, the dispersion was good, and the average particle size of the catalyst was 16.8 μm.

[0118] Comparative Example 4

[0119] In a 1L continuous stirred tank reactor, 200g of solvent (38.5wt% H₂O, 61.5wt% TDA) was added as the reaction base liquid, along with 4g of Raney nickel catalyst (average particle size 16µm). At room temperature, the reactor was purged three times with high-purity nitrogen to remove residual air, followed by four times with high-purity hydrogen until the hydrogen concentration in the purging gas exceeded 99.9 vol%. After successful purging, the reactor was pressurized to 21 barg, the stirring speed was controlled at 1100 rpm, and the reactor temperature was raised to 170℃. The DNT / (kg catalyst*h) mass hourly space velocity was 5.7 kg DNT / (kg catalyst*h). The hydrogen to DNT mass ratio was controlled at 8:1, and the reaction liquid withdrawal rate was controlled to maintain the initial liquid holdup in the reactor. The reaction was then initiated. After 12 hours of reaction, samples were taken for testing, showing a DNT conversion of 98.93% and a TDA selectivity of 96.37%.

[0120] After the reaction continued for 120 hours, samples were taken for testing. The conversion rate of dinitrotoluene was 98.12%, the TDA selectivity was 94.36%, the catalyst agglomeration in the reactor was obvious, and the average particle size of the catalyst was 12.7 μm.

Claims

1. A hydrogenation catalyst comprising a support and an active component and an auxiliary agent attached to the support, characterized in that, The carrier is surface-modified hollow glass microspheres; the active component includes one or more than two of Ni, Pd, Pt, Rh, Ra, Ru, and the auxiliary agent is selected from one or more of the metals Li, Na, Cs, Co, Cr, Ir, Mn, and Sr; The preparation of the surface-modified hollow glass microspheres includes the following steps: S1: toluene diamine tar is mixed with an activating agent, and polymerization is carried out under an oxygen atmosphere to obtain a polymerization solution, and then the polymerization solution is activated by an alkaline solution under an inert gas atmosphere to obtain a polymer amine modified solution; S2: hollow glass microspheres and a sodium tripolyphosphate solution are added to the polymer amine modified solution obtained in step S1, washed to neutral, filtered, dried, calcined, and fully ground to obtain a catalyst carrier; S3: an alkali metal fluoride is dissolved in water, and the catalyst carrier prepared in step S2 is added, washed, filtered, dried, and calcined to obtain the surface-modified hollow glass microsphere carrier; The toluene diamine tar in step S1 contains 10-50 wt% toluene diamine, and the activating agent is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

2. The hydrogenation catalyst according to claim 1, characterized by The content of the active component is 0.05-50 wt% of the mass of the surface-modified hollow glass microsphere carrier.

3. The hydrogenation catalyst according to claim 2, characterized in that, The content of the active component is 0.1-35 wt% of the mass of the surface-modified hollow glass microsphere carrier.

4. The hydrogenation catalyst according to claim 2, characterized by The content of the active component is 0.5-15 wt% of the mass of the surface-modified hollow glass microsphere carrier.

5. The hydrogenation catalyst of claim 1, wherein The content of the auxiliary agent is 0.01-0.5 wt% of the mass of the surface-modified hollow glass microsphere carrier.

6. The hydrogenation catalyst according to claim 5, characterized in that, The content of the auxiliary agent is 0.05-0.1 wt% of the mass of the surface-modified hollow glass microsphere carrier.

7. A method for preparing the hydrogenation catalyst of any one of claims 1-6, comprising the following steps: (a) preparing a surface-modified hollow glass microsphere carrier; (b) mixing the carrier prepared in step (a), a soluble metal salt of the active component, and a soluble metal salt of the auxiliary agent, adding an alkali to adjust the pH, and stirring and impregnating; (c) adding a reducing agent to reduce, and then washing with water, drying, to obtain the hydrogenation catalyst.

8. The method of claim 7, wherein, In step S1, the activating agent is configured to be used in an aqueous solution, and the mass concentration is 10-30 wt%.

9. The method of claim 7, wherein, In step S1, the mass ratio of toluene diamine tar to activating agent is 1:(0.1-5).

10. The method of claim 9, wherein, In step S1, the mass ratio of toluene diamine tar to activating agent is 1:(0.1-2).

11. The method of claim 7, wherein, In step S1, the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, urea, and hydrogenation wastewater, wherein the concentration of organic matter in the hydrogenation wastewater is 0.1-3 wt%, and the concentration of the sodium hydroxide, potassium hydroxide, and urea solution is 10-20 wt%.

12. The method of claim 11, wherein, In step S1, the mass ratio of the alkaline solution to the polymerization solution is 1:(0.2-10).

13. The method of claim 7, wherein, In step S1, the activation time is 0.5-5 h, and the activation temperature is 300-700℃.

14. The method of claim 7, wherein, In step S2, the mass ratio of hollow glass microspheres to the polymer amine modified solution is 1:(1-10).

15. The method of claim 7, wherein, In step S2, the amount of sodium tripolyphosphate is 0.01-0.2 g per 1 g of hollow glass microspheres.

16. The method of claim 7, wherein, In step S2, the calcination temperature is 400-550℃.

17. The method of claim 7, wherein, The alkali metal fluoride in step S3 is selected from one or more of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, and cesium fluoride.

18. The method of claim 7, wherein, The mass of the alkali metal fluoride in step S3 is 10-30% of the mass of the catalyst carrier.

19. The method of claim 18, wherein, The mass of the alkali metal fluoride is 10-20% of the mass of the catalyst carrier.

20. The method of claim 7, wherein, The calcination temperature in step S3 is 300-500℃.

21. The method of claim 7, wherein, The base in step (b) is selected from potassium hydroxide, sodium hydroxide, and aqueous ammonia, and the pH is adjusted to 8-12.

22. The method of claim 21, wherein, The pH in step (b) is adjusted to 9-11.

23. The method of claim 7, wherein, The reducing agent in step (c) is at least one of hydrogen, formaldehyde, hydrazine hydrate, and sodium sulfite.

24. Use of the hydrogenation catalyst according to any one of claims 1-6 in catalyzing the hydrogenation of aromatic nitro compounds to prepare aromatic amines.