Catalyst for preparing benzene by means of cyclohexane dehydrogenation, and preparation method therefor and use thereof

Abstract

The present invention relates to a catalyst for cyclohexane dehydrogenation, and a preparation method therefor and the use thereof. The catalyst is a supported catalyst, wherein alumina is used as a carrier, and the carrier is loaded with active Pt and an auxiliary agent. On the basis of the weight of the catalyst, the content of Pt is 0.05-1.2%, and the content of the auxiliary agent is 0.1-2.0%, wherein the auxiliary agent contains a rare-earth metal and an alkaline earth metal. The catalyst of the present invention is used for catalyzing a cyclohexane dehydrogenation reaction, the cyclohexane conversion rate can reach up to 99.99%, the benzene yield can reach up to 99.9% or above, and thus the catalyst has high industrial application value.

Description

Catalyst for preparing benzene by dehydrogenation of cyclohexane and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic material preparation and application, and particularly relates to a catalyst for preparing benzene by dehydrogenation of cyclohexane and a preparation method and application thereof. BACKGROUND

[0002] Benzene is an important organic chemical raw material in modern chemical industry, which is widely used in various fields and has a profound influence on national economy and social development. In many industries such as synthetic rubber, plastic, fiber, detergent, dye, medicine, benzene is an indispensable key component, and its importance is self-evident. Since September 1998, Henan Shenma Group first introduced the technology of producing cyclohexanol by partial hydrogenation of benzene to produce cyclohexene and then hydrating cyclohexene for adipic acid and caprolactam industry, the partial hydrogenation method of benzene gradually replaced the old process of complete hydrogenation of benzene to produce cyclohexane and then oxidizing cyclohexane to produce alcohol and ketone. As of 2020, the production capacity of the benzene partial hydrogenation process reached 3 million tons / a. The selectivity of cyclohexene in the benzene partial hydrogenation process is basically maintained at about 80%, and the by-product is mainly cyclohexane. By dehydrogenating the by-product cyclohexane to regenerate benzene and hydrogen, which is sent back to the benzene partial hydrogenation device as raw material, the raw material utilization rate can be effectively improved, so the development and application of the supporting process of cyclohexane dehydrogenation to produce benzene are imminent.

[0003] The cyclohexane dehydrogenation reaction process is called catalytic reforming in the petrochemical industry, and relevant technical personnel at home and abroad have also conducted extensive research on this technology. Patent CN110882703A discloses a cycloalkane dehydrogenation catalyst containing an alkaline earth metal and a preparation method thereof. The catalyst uses Pt as the active metal component, Sn as the additive, and the carrier is an alumina carrier containing an alkaline earth metal, sulfur and titanium. However, the invention only highlights the carbon deposition resistance of the catalyst at high temperature, and the benzene yield is not high, only 84.3%.

[0004] Patent CN106693993A discloses a sulfur-containing type low-carbon alkane dehydrogenation catalyst and a preparation method thereof. The catalyst uses Pt as the active metal component and Sn as the additive component, and the carrier is an alumina containing sulfur and alkali metal. The catalyst is mainly used for catalyzing the dehydrogenation of low-carbon alkanes such as propane and butane to produce low-carbon olefins, which has a large gap with the dehydrogenation of cyclohexane to produce benzene, which is reflected in the difference in molecular size and the difference in enthalpy change of dehydrogenation.

[0005] A metal-supported cyclohexane dehydrogenation catalyst and a preparation method thereof are disclosed in patent CN111686718A. The catalyst uses Pt as the active metal component, the carrier is γ-Al2O3, and 0.75-1.0% of Na2CO3 is further used. In the preparation process, the carrier needs to be treated with alkali first, and then an ammonia complex impregnation solution is prepared for long-time impregnation. Alkaline complexing agents such as ammonia and organic amines and pH regulators are required, the preparation process is complicated, time-consuming and difficult to control, and it is easy to cause high carrier wear rate and aggravate the loss of noble metal Pt.

[0006] Patent CN106140155A discloses a catalyst for dehydrogenation of pentane or hexane to olefins, a preparation method and application thereof. The catalyst uses alumina as the carrier, and one or two or more of Rh, Ru, Pt or Pd as the main active component, and other elements as the auxiliary active component, which can catalyze the dehydrogenation of n-hexane or n-pentane to olefins. However, the conversion rate of alkanes is not high, and according to the example data, this method is mainly suitable for the dehydrogenation of n-hexane or n-pentane.

[0007] Patent CN105037066A discloses a method for one-step preparation of Pt / C catalyst and dehydrogenation of methylcyclohexane. However, the catalyst preparation method is too complex, and the presence of methyl in methylcyclohexane is beneficial to the dehydrogenation reaction, so the dehydrogenation temperature is relatively low.

[0008] Therefore, the current cyclohexane dehydrogenation process for preparing benzene faces many challenges, among which the most critical one is the lack of a catalyst that can achieve high activity, high conversion rate, high yield and good stability under mild conditions. SUMMARY

[0009] In view of the above problems, the present application provides a cyclohexane dehydrogenation catalyst with high activity, high stability, high conversion rate and high yield, a preparation method and application thereof. The catalyst is used for dehydrogenation of cyclohexane to obtain high-purity benzene and hydrogen, improves the utilization rate of raw materials in the device, and reduces the production cost.

[0010] The present application provides a cyclohexane dehydrogenation catalyst, which is a supported catalyst using alumina as the carrier, and the carrier is loaded with active Pt and an auxiliary agent. The content of Pt is 0.05-1.2% and the content of the auxiliary agent is 0.1-2.0% based on the weight of the catalyst. The auxiliary agent contains rare earth metals and alkaline earth metals.

[0011] In some specific embodiments of the present application, the alkaline earth metal is selected from magnesium, calcium, strontium and barium.

[0012] In some specific embodiments of the present application, the alkaline earth metal is barium.

[0013] In the patent CN106693993A, patent CN110882703A and some prior art, alkaline earth metals are used, but the effect is not very good, the benzene yield is only 84.3%, the inventors have tried many methods involved in patents, and prepared different catalysts by adding different alkaline earth metals (such as magnesium, calcium, strontium, barium), but there are many problems, such as low cyclohexane conversion rate, low benzene yield, or the need for high loading of active component Pt. The inventors tried to combine alkaline earth metals with rare earth metals, and accidentally found that the conversion rate of cyclohexane and the yield of benzene of alkaline earth metal barium and rare earth metal yttrium in a certain ratio increased greatly, and the highest could reach 99.99% and 99.9%, respectively.

[0014] In some embodiments of the present application, the rare earth metal is selected from lanthanum, cerium, praseodymium, neodymium, samarium, lutetium, scandium and yttrium.

[0015] In some embodiments of the present application, the rare earth metal is selected from yttrium.

[0016] In some embodiments of the present application, the content of the rare earth metal is 0.1-1.5% based on the weight of the catalyst.

[0017] In some embodiments of the present application, the content of the rare earth metal is 0.1-1.0%.

[0018] In some embodiments of the present application, the content of the alkaline earth metal is 0.1-0.5% based on the weight of the catalyst.

[0019] In some embodiments of the present application, the content of the alkaline earth metal is 0.2-0.4%.

[0020] In some embodiments of the present application, the auxiliary agent is selected from soluble salts such as nitrate, chloride, carbonate, sulfate and ammonium salt. The use of soluble salts of these auxiliary agent components is beneficial to the preparation of auxiliary agent impregnation solution.

[0021] In some embodiments of the present application, the soluble salts of the rare earth metal and the alkaline earth metal are both nitrate.

[0022] The present application provides a preparation method of cyclohexane dehydrogenation catalyst, which comprises the following steps:

[0023] (1) preparing an alumina carrier;

[0024] (2) impregnating active components and auxiliary agents;

[0025] (3) drying and calcining to obtain the cyclohexane dehydrogenation catalyst.

[0026] In the present invention, the method for preparing alumina can be method 1: contacting sodium metaaluminate or sodium aluminate solution with one or more of aluminum sulfate, aluminum nitrate, aluminum chloride, nitric acid and sulfuric acid solution, carrying out a primary coagulation reaction, which can be carried out in a continuous manner, aging the obtained aluminum hydroxide, separating the solid and liquid, washing, drying and calcining the obtained solid product; wherein the pH value of the primary coagulation reaction is 6-9.5.

[0027] The concentration of the sodium metaaluminate or sodium aluminate solution and the concentration of the aluminum sulfate, aluminum nitrate, aluminum chloride, nitric acid and sulfuric acid solution can be any possible concentration, as long as the pH value of the primary coagulation reaction is 6-9.5. In order to efficiently prepare pseudoboehmite, the concentration of the sodium metaaluminate or sodium aluminate solution is preferably 30-300 g alumina / liter, the concentration of the aluminum sulfate, aluminum nitrate and aluminum chloride is preferably 10-120 g alumina / liter, and the concentration of the nitric acid and sulfuric acid solution is preferably 5-15 wt.%.

[0028] In some embodiments of the present invention, the pH value of the primary coagulation reaction is preferably 8.5-9.5.

[0029] The method for separating the solid and liquid can use conventional methods, such as filtration or centrifugal separation.

[0030] The washing is carried out according to conventional methods, and the purpose of the washing is to remove impurity ions such as sulfate ions and sodium ions. The washing should be such that the content of alkali metal oxides in the formed alumina is not more than 0.15 wt.%, and the content of sulfate ions is not more than 2 wt.%.

[0031] When preparing the alumina carrier, a shaping step can also and preferably be carried out before drying. The shaping method can use various existing methods, such as tablet shaping, ball shaping, extrusion strip shaping, etc., and the extrusion strip shaping method is preferred. Various existing peptizing agents and / or extrusion aids can be added during the shaping process. The peptizing agent can be various inorganic or organic acids, such as hydrochloric acid, nitric acid, citric acid, acetic acid, etc. The extrusion aid can be starch substances, cellulose substances, etc.

[0032] The drying conditions are conventional drying conditions, and the drying temperature can be room temperature to below the pseudoboehmite crystallization temperature, preferably 60-200°C.

[0033] The calcination conditions are conventional calcination conditions, such as a calcination temperature of 500-900°C, preferably 500°C, and a calcination time of 2-8 hours, preferably 3-6 hours.

[0034] In the present application, the method for preparing alumina can also be method 2: contacting sodium metaaluminate or sodium aluminate solution with a gas containing carbon dioxide, forming gel in an intermittent or continuous manner, aging the obtained aluminum hydroxide, separating the solid and liquid, washing, drying and calcining the obtained solid product. In the method, the end point pH value or process pH value of the gel formation is controlled in the range of 6-9.5, the time or residence time of the gel formation reaction is less than 40 minutes, the temperature of the gel formation reaction is 10-100°C, and after the gel formation reaction, an alkaline substance is rapidly added to raise the pH value of the slurry to above 9.5 or the solid-liquid separation is rapidly performed and washing is performed.

[0035] In the method, the concentration of the sodium metaaluminate or sodium aluminate solution can be any possible concentration, and to ensure efficient preparation of pseudoboehmite, the concentration of the sodium metaaluminate or sodium aluminate solution is preferably 5-200 g of alumina per liter, and more preferably 5-120 g of alumina per liter.

[0036] The gas containing carbon dioxide can be pure carbon dioxide gas or a mixed gas composed of carbon dioxide and an inert gas that does not affect the reaction, such as air, nitrogen, helium, argon or the like. The content of carbon dioxide in the gas containing carbon dioxide can vary in a wide range, and in general, the content of carbon dioxide is not less than 5% by volume, and preferably not less than 20% by volume.

[0037] The gel formation reaction can be intermittent. In this case, the sodium metaaluminate or sodium aluminate solution is first placed in a gel formation tank, the gas containing carbon dioxide is introduced from the bottom of the tank, the reaction temperature is controlled in the range of 10-100°C, and preferably 10-80°C, and the end point pH value is controlled in the range of 6-9.5, and preferably 6.5-9.3. By adjusting the concentration and amount of the sodium metaaluminate or sodium aluminate solution and the concentration and flow rate of the carbon dioxide-containing gas, the time of the gel formation reaction is not more than 40 minutes, and preferably not more than 30 minutes. After the gel formation reaction, an alkaline substance is rapidly added to rapidly raise the pH value of the slurry to above 9.5, and preferably 9.5-11.5, or the solid-liquid separation is rapidly performed and washing is performed. Then, aging, filtration, washing and drying are performed under conventional conditions to obtain pseudoboehmite, and after calcination, an alumina carrier is formed.

[0038] The gelation reaction can also be continuous. When this mode of gelation is used, deionized water is first introduced into a gelation tank, and carbon dioxide-containing gas is introduced from the bottom of the tank and sodium metaaluminate or sodium aluminate solution is introduced from the top of the tank, so that the sodium metaaluminate or sodium aluminate solution and the carbon dioxide-containing gas are countercurrently contacted. The gelation temperature is controlled to be in the range of 10 to 100°C, preferably in the range of 10 to 80°C. The concentration and flow rate of the sodium metaaluminate or sodium aluminate solution and the concentration and flow rate of the carbon dioxide-containing gas are controlled so that the pH during the gelation process is in the range of 6 to 9.5, preferably in the range of 6.5 to 9.3, and the residence time is not more than 40 minutes, preferably not more than 30 minutes. The slurry produced during the gelation process is continuously or intermittently collected in an aging tank, and a basic substance is continuously or intermittently added to raise the pH of the slurry to more than 9.5, preferably in the range of 9.5 to 11.5. After a period of time, the slurry produced during the gelation process is switched to another aging tank, and the slurry in the first aging tank having a pH of more than 9.5 is aged, filtered, washed, and dried to obtain pseudoboehmite, which is calcined to obtain an alumina carrier.

[0039] The basic substance is selected from one or more of inorganic bases, organic bases, and aqueous solutions thereof. The inorganic base is preferably selected from one or more of hydroxides of alkali metals, metaaluminate salts, carbonate salts, bicarbonate salts, ammonium carbonate, aqueous ammonia, and aqueous solutions thereof. The organic base is preferably selected from one or more of water-soluble amines, urea, pyridine, and aqueous solutions thereof, preferably one or more of water-soluble aliphatic amines, hydroxides of ammonium hydrocarbyls, urea, pyridine, and aqueous solutions thereof, and particularly one or more of methylamine, ethylamine, propylamine, propylenediamine, various isomers of butylamine, various isomers of amylamine, tetraethylammonium hydroxide, urea, pyridine, and aqueous solutions thereof.

[0040] The method of solid-liquid separation can employ filtration or centrifugal separation. Washing after the rapid solid-liquid separation is performed to remove sodium bicarbonate, which is a reactant for the formation of dawsonite, and is generally performed at least once using deionized water in an amount of not less than 10 times the weight of the solid product.

[0041] The aging is performed under conventional conditions, and is generally performed at a temperature in the range of 5 to 100°C, preferably in the range of 30 to 100°C, and more preferably in the range of 50 to 100°C, for a period of time of more than 0.5 hour, preferably in the range of 1 to 8 hours. When the method of adjusting the pH by adding a basic substance is used, the medium for the aging can be the mother liquor or deionized water. When the method of rapid solid-liquid separation is used, the medium for the aging is generally deionized water.

[0042] The washing after the aging is performed by a conventional method, and is performed to remove impurity ions, so that the content of alkali metal oxides is less than 0.15 wt.%.

[0043] The drying condition is a conventional drying condition, and the drying temperature can be room temperature to below pseudo-boehmite transformation temperature, preferably 100-200 DEG C.

[0044] When preparing the alumina carrier, a molding step as described above can also be and preferably is performed before drying.

[0045] The calcination condition is a conventional calcination condition, such as a calcination temperature of 500-900 DEG C, preferably 550-850 DEG C, and a calcination time of 2-8 hours, preferably 3-6 hours.

[0046] In some embodiments of the present application, the method for preparing the alumina comprises mixing sodium aluminate and aluminum sulfate solution, maintaining the pH in the range of 8.5-9.5, filtering, washing, drying, and calcining after the gelation reaction to obtain the alumina carrier.

[0047] In some embodiments of the present application, after the impregnation in step (2), the carrier is added into a rotary evaporation flask, rotated at 1-6 r / min for 20-40 min, and then vacuum-evaporated to remove the excess water until the surface of the carrier is dry, and then removed for the subsequent drying step.

[0048] In some embodiments of the present application, in step (3), the drying temperature is 60 DEG C-100 DEG C, and the drying time is 5-8 hours.

[0049] In the present application, the drying temperature is any value selected from 60 DEG C, 70 DEG C, 80 DEG C, 90 DEG C, and 100 DEG C, or a range value between any two of them; and the drying time is any value selected from 5 h, 6 h, 7 h, and 8 h, or a range value between any two of them.

[0050] In some embodiments of the present application, in step (3), the calcination temperature is 550-650 DEG C, and the calcination time is 6-10 hours.

[0051] In the present application, the calcination temperature is any value selected from 550 DEG C, 560 DEG C, 570 DEG C, 580 DEG C, 590 DEG C, 600 DEG C, 610 DEG C, 620 DEG C, 630 DEG C, 640 DEG C, and 650 DEG C, or a range value between any two of them; and the calcination time is any value selected from 6 h, 7 h, 8 h, 9 h, and 10 h, or a range value between any two of them.

[0052] The present application provides a method for preparing benzene by dehydrogenation of cyclohexane, comprising the following steps: catalyzing the dehydrogenation of cyclohexane by the cyclohexane dehydrogenation catalyst as described above, and reacting under the conditions of a cyclohexane space velocity of 2.0-5.0 h -1 , a hydrogen flow rate of 5-15 mL / min, a reaction temperature of 400-450 DEG C, and a hydrogen pressure of 0.2-0.6 MPa to obtain a product, and analyzing the product by gas chromatography.

[0053] In the present application, the mass space velocity of the cyclohexane is any value among 2h -1 , 3h -1 , 4h -1 , 5h -1 or a range value between any two of them.

[0054] In the present application, the hydrogen flow is any value among 5 mL / min, 6 mL / min, 7 mL / min, 8 mL / min, 9 mL / min, 10 mL / min, 11 mL / min, 12 mL / min, 13 mL / min, 14 mL / min, 15 mL / min or a range value between any two of them.

[0055] In the present application, the temperature of the reaction is any value among 420℃, 430℃, 440℃, 450℃ or a range value between any two of them.

[0056] In the present application, the pressure of the reaction is any value among 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa or a range value between any two of them.

[0057] In some specific embodiments of the present application, the cyclohexane space velocity is 4h -1 , the hydrogen flow is 10 mL / min, the reaction temperature is 420-450℃, and the hydrogen pressure is 0.28-0.35 MPa.

[0058] In some specific embodiments of the present application, the reactor is a fixed bed reactor.

[0059] Compared with the prior art, the present application has the following beneficial effects:

[0060] (1) The catalyst provided by the present application can be applied to the cyclohexane dehydrogenation reaction to prepare benzene and improve the conversion rate of cyclohexane and the yield of the generated benzene.

[0061] (2) The method for preparing the catalyst of the present application is simple, efficient and environmentally friendly, reduces the loss of noble metals, and has a small amount of carbon deposition.

[0062] (3) The method for preparing benzene by cyclohexane dehydrogenation reaction provided by the present application uses the catalyst provided by the present application, has a fast reaction speed and a high yield, and can be applied to large-scale production. DETAILED DESCRIPTION

[0063] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0064] Example 1

[0065] Preparation of the carrier:

[0066] Into a gelatinizing tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added for acidification for 1 hour, and 0.3 liters of water was added for slurry into sol. Using the oil column forming method, small spherical bodies were formed by dripping into the oil ammonia column, and were solidified in the ammonia column for 2 hours, then were filtered, washed with deionized water for three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, and calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain the alumina ball carrier.

[0067] Preparation of the catalyst:

[0068] Take 97.6 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 hours, dissolve 2.31 g of chloroplatinic acid, 0.57 g of barium nitrate, and 3.09 g of yttrium nitrate in 120 g of water to prepare a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, evaporate the excess water under vacuum, take out after the surface of the carrier is dry, then dry at 80°C for 6 hours, and calcine at 600°C for 8 hours, to prepare the catalyst A.

[0069] Example 2

[0070] Preparation of the carrier (same as Example 1), as follows:

[0071] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0072] Preparation of catalyst:

[0073] Take 97.7 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 hours, dissolve 2.10 g of chloroplatinic acid, 0.57 g of barium nitrate, and 3.09 g of yttrium nitrate in 120 g of water to prepare a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out after the surface of the carrier is dry, then dry at 80°C for 6 hours, and calcine at 600°C for 8 hours, to prepare catalyst B.

[0074] Example 3

[0075] Preparation of carrier (same as Example 1), as follows:

[0076] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0077] Preparation of catalyst:

[0078] Take 97.8 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.57 g of barium nitrate and 3.09 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst C.

[0079] Example 4

[0080] Preparation of the carrier (same as Example 1), specifically as follows:

[0081] Into a gelatinizing tank, add 2 liters of water, and drop in sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) under stirring, and control the dropping speed of the sodium aluminate solution and the aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate are added. After filtration and water washing, add 13 ml of dilute nitric acid (1:1 by volume) to acidify for 1 h, and then add 0.3 liters of water to beat into sol. Use the oil column forming method to drop into small spherical blanks in the oil ammonia column, and solidify in the ammonia column for 2 h, then filter, wash with deionized water for 3 times, dry at 60 °C for 6 h, dry at 120 °C for 2 h, and calcine at 500 °C in a flowing air atmosphere for 4 h to obtain the alumina ball carrier.

[0082] Preparation of the catalyst:

[0083] Take 97.9 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.57 g of barium nitrate and 3.09 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst D.

[0084] Example 5

[0085] Preparation of the carrier (same as Example 1), specifically as follows:

[0086] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0087] Preparation of catalyst:

[0088] Take 98.0 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 hours, dissolve 1.47 g of chloroplatinic acid, 0.57 g of barium nitrate, and 3.09 g of yttrium nitrate in 120 g of water to prepare a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out after the surface of the carrier is dry, then dry at 80°C for 6 hours, and calcine at 600°C for 8 hours, to prepare catalyst E.

[0089] Example 6

[0090] Preparation of carrier (same as Example 1), as follows:

[0091] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0092] Preparation of catalyst:

[0093] Take 98.1 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.26 g of chloroplatinic acid, 0.57 g of barium nitrate and 3.09 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst F.

[0094] Example 7

[0095] The carrier is prepared (same as in Example 1) as follows:

[0096] Into a gelatinizing tank, 2 liters of water is added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) are added dropwise under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution is controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate are added. After filtration and water washing, 13 ml of dilute nitric acid (1:1 by volume) is added to acidify for 1 h, and 0.3 liters of water is added to make it into sol. The oil column forming method is used to drop into small spherical blanks in the oil ammonia column, and solidify in the ammonia column for 2 h, then filter, wash with deionized water for 3 times, dry at 60 °C for 6 h, dry at 120 °C for 2 h, calcine at 500 °C for 4 h in a flowing air atmosphere to obtain the alumina ball carrier.

[0097] Preparation of the catalyst:

[0098] Take 97.8 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.57 g of barium nitrate and 2.472 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst G.

[0099] Example 8

[0100] The carrier is prepared (same as in Example 1) as follows:

[0101] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0102] Preparation of catalyst:

[0103] Take 98.1 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 hours, dissolve 1.89 g of chloroplatinic acid, 0.57 g of barium nitrate, and 2.781 g of yttrium nitrate in 120 g of water to prepare a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out when the surface of the carrier is dry, then dry at 80°C for 6 hours, and calcine at 600°C for 8 hours, to prepare catalyst H.

[0104] Example 9

[0105] Preparation of carrier (same as Example 1), as follows:

[0106] To a gel-making tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0107] Preparation of catalyst:

[0108] Take 97.7 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.381 g of barium nitrate and 3.399 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst I.

[0109] Example 10

[0110] The carrier is prepared (same as in Example 1) as follows:

[0111] Into a gelatinizing tank, 2 liters of water is added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) are added dropwise under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution is controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate are added. After filtration and water washing, 13 ml of dilute nitric acid (1:1 by volume) is added to acidify for 1 h, and 0.3 liters of water is added to make it into sol. The oil column forming method is used to drop into small spherical blanks in the oil ammonia column, and solidify in the ammonia column for 2 h, then filter, wash with deionized water for 3 times, dry at 60 °C for 6 h, dry at 120 °C for 2 h, calcine at 500 °C for 4 h in a flowing air atmosphere to obtain the alumina ball carrier.

[0112] Preparation of the catalyst:

[0113] Take 97.7 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.381 g of barium nitrate and 3.399 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80 °C for 6 h, and calcine at 600 °C for 8 h to obtain catalyst I.

[0114] Example 11

[0115] The carrier is prepared (same as in Example 1) as follows:

[0116] To a gelatinizing tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0117] Preparation of the catalyst:

[0118] Take 97.85 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 hours, dissolve 1.89 g of chloroplatinic acid, 0.476 g of barium nitrate, and 3.09 g of yttrium nitrate in 120 g of water to prepare a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out after the surface of the carrier is dry, then dry at 80°C for 6 hours, and calcine at 600°C for 8 hours, to prepare the catalyst K.

[0119] Example 12

[0120] Preparation of the carrier (same as Example 1), as follows:

[0121] To a gelatinizing tank, 2 liters of water was added, and sodium aluminate solution (Na2O 150 g / L, Al2O3 100 g / L) and aluminum sulfate solution (Al2O3 90 g / L) were added dropwise simultaneously under stirring, and the dropping speed of the sodium aluminate solution and the aluminum sulfate solution was controlled respectively to keep the pH of the material in the range of 8.5-9.5, about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate were added. After filtration and water washing, 13 milliliters of dilute nitric acid (1:1 volume) was added to acidify for 1 hour, and 0.3 liters of water was added to pulp into sol. Using the oil column forming method, small spherical green bodies were formed in the oil ammonia column, and were solidified in the ammonia column for 2 hours, then filtered, washed with deionized water three times, dried at 60°C for 6 hours, dried at 120°C for 2 hours, calcined at 500°C for 4 hours in a flowing air atmosphere, to obtain an alumina ball carrier.

[0122] Preparation of the catalyst:

[0123] Take 97.75 g of the alumina ball carrier prepared above into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid, 0.667 g of barium nitrate and 3.09 g of yttrium nitrate in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80°C for 6 h, and calcine at 600°C for 8 h to prepare catalyst L.

[0124] Comparative Example 1

[0125] Take 98.8 g of the carrier prepared in Example 1 into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.89 g of chloroplatinic acid in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80°C for 6 h, and calcine at 600°C for 8 h to prepare Comparative Agent A.

[0126] Comparative Example 2

[0127] Take 98.9 g of the carrier prepared in Example 1 into a rotary evaporation flask, vacuumize for 2 h, dissolve 1.68 g of chloroplatinic acid in 120 g of water to form a solution, immerse the solution into the rotary evaporation flask with the carrier, rotate at 2 r / min for 30 min, vacuumize to evaporate the excess water, take out the carrier when the surface of the carrier is dry, then dry at 80°C for 6 h, and calcine at 600°C for 8 h to prepare Comparative Agent B.

[0128] Test Example 1

[0129] In Examples 1-12 and Comparative Examples 1-2, the catalyst evaluation was performed by the following method: the prepared catalyst was placed in a fixed bed reactor, cyclohexane was pumped into the fixed bed reactor by a feed pump, the mass space velocity was 4 h - 1 , hydrogen was introduced into the fixed bed reactor by a gas flow meter, the hydrogen flow was 10 mL / min, the reaction was performed at 420-450°C and a reaction pressure of 0.28-0.35 MPa, the product composition was analyzed by gas chromatography during the reaction process. The contents of Pt, Ba, Y and C in the catalyst were detected by ICP-MS. The catalyst composition is shown in Table 1 and the evaluation results are shown in Table 2.

[0130] Table 1 Catalyst composition

[0131] Table 2 Catalyst performance

[0132] From the data in Table 1 and Table 2, it can be seen that after the addition of the rare earth metal yttrium and the alkaline earth metal barium, the conversion of cyclohexane and the yield of benzene are obviously improved. When the content of Pt is 0.896%, the content of Ba is 0.299% and the content of Y is 0.993, the conversion of cyclohexane can reach 99.99%, the yield of benzene can reach 99.98% and the amount of carbon deposition is 1.89%. In addition, when the content of Pt is reduced to 0.601, the conversion of cyclohexane can still be maintained at more than 99.6%, the yield of benzene is more than 98% and the amount of carbon deposition is 1.76%.

[0133] While the embodiments of the application have been shown and described, it is to be understood that the embodiments described are only by way of example and that modifications, changes, substitutions and variations can be made by those skilled in the art without departing from the spirit and scope of the application, which is defined solely by the claims and their equivalents.

Claims

1. A cyclohexane dehydrogenation catalyst characterized in that, It is a supported catalyst, taking alumina as carrier, which is loaded with active Pt and adjuvant, the content of Pt is 0.05-1.2% and the content of adjuvant is 0.1-2.0% based on the weight of the catalyst; the adjuvant contains rare earth metal and alkaline earth metal.

2. The cyclohexane dehydrogenation catalyst of claim 1, wherein, The rare earth metal is selected from lanthanum, cerium, praseodymium, neodymium, samarium, lutetium, scandium and yttrium; further, the rare earth metal is selected from yttrium.

3. The cyclohexane dehydrogenation catalyst of claim 1, wherein, The alkaline earth metal is selected from magnesium, calcium, strontium and barium; further, the alkaline earth metal is barium.

4. The cyclohexane dehydrogenation catalyst of claim 1, wherein, The content of the rare earth metal is 0.1-1.5% based on the weight of the catalyst; further, the content of the rare earth metal is 0.1-1.0%.

5. The cyclohexane dehydrogenation catalyst of claim 1, wherein, The content of the alkaline earth metal is 0.1-0.5% based on the weight of the catalyst; further, the content of the alkaline earth metal is 0.2-0.4%.

6. Process for the preparation of a cyclohexane dehydrogenation catalyst according to any one of claims 1 to 5, characterized in that, It comprises the following steps: (1) preparing alumina carrier; (2) impregnating active component and adjuvant; (3) drying and calcining, thus obtaining the said cyclohexane dehydrogenation catalyst.

7. The process for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized in that, The preparation method of the alumina carrier is as follows: contacting sodium metaaluminate or sodium aluminate solution with one or several of aluminum sulfate, aluminum nitrate, aluminum chloride, nitric acid and sulfuric acid solution, reacting, aging the obtained aluminum hydroxide, separating solid and liquid, washing, drying and calcining the obtained alumina carrier.

8. The process for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized by, In step (3), the drying temperature is 60-100℃ and the drying time is 5-8 hours.

9. The process for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized by, In step (3), the calcining temperature is 550-650℃ and the calcining time is 6-10 hours.

10. A process for the dehydrogenation of cyclohexane to benzene comprising the steps of: The cyclohexane dehydrogenation catalyst according to any one of claims 1-5 is used to catalyze the dehydrogenation reaction of cyclohexane, under the conditions of a cyclohexane space velocity of 2.0-5.0 h -1 , a hydrogen flow rate of 5-15 mL / min, a reaction temperature of 400-450 DEG C, and a hydrogen pressure of 0.2-0.6 MPa, to obtain a product, which is analyzed by gas chromatography; further, the cyclohexane space velocity is 4 h -1 , the hydrogen flow rate is 10 mL / min, the reaction temperature is 420-450 DEG C, and the hydrogen pressure is 0.28-0.35 MPa.

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