Catalyst for preparing benzene through cyclohexane dehydrogenation as well as preparation method and application of catalyst

Abstract

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

Description

Technical Field

[0001] The present invention relates to the catalytic material preparation technology and application field, and in particular to a catalyst for preparing benzene by dehydrogenating cyclohexane, and a preparation method and application thereof. Background Art

[0002] As a vital organic chemical raw material in the modern chemical industry, benzene is widely used in various fields and has a profound impact on the national economy and social development. In many industries such as synthetic rubber, plastics, fibers, detergents, dyes, and medicines, benzene is an indispensable key component, and its importance is self-evident. Since September 1998, Henan Shenma Group first introduced the partial hydrogenation of benzene to produce cyclohexene and cyclohexene hydration to produce cyclohexanol technology for adipic acid and caprolactam industries. The partial hydrogenation of benzene has gradually replaced the old process of complete hydrogenation of benzene to produce cyclohexane and cyclohexane oxidation to produce alcohols and ketones. As of 2020, the production capacity of the partial hydrogenation process of benzene has reached 3 million tons / a. The selectivity of cyclohexene in the partial hydrogenation of benzene is basically maintained at about 80%, and the by-product is mainly cyclohexane. By dehydrogenating the by-product cyclohexane to regenerate benzene and hydrogen, and sending it back to the partial hydrogenation unit of benzene as raw materials, the utilization rate of raw materials can be effectively improved. Therefore, the development and application of supporting processes for cyclohexane dehydrogenation to produce benzene is imminent.

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

[0004] Patent CN106693993A discloses a sulfur-containing low-carbon alkane dehydrogenation catalyst and its preparation method, which uses Pt as an active metal component, Sn as an auxiliary component, and alumina containing sulfur and alkali metals as a carrier. The catalyst is mainly used to catalyze the dehydrogenation of low-carbon alkanes such as propane and butane to produce low-carbon olefins, which is far behind the dehydrogenation of cyclohexane to produce benzene, as reflected in the different molecular sizes and different enthalpy changes of dehydrogenation.

[0005] Patent CN111686718A discloses a metal-supported cyclohexane dehydrogenation catalyst and its preparation method. The catalyst uses Pt as an active metal component, and the carrier is γ-Al2O3, and the content is 0.75-1.0%. During the preparation process, the carrier needs to be alkaline treated first, and then an ammonia complex impregnation solution is prepared for long-term impregnation. Ammonia water, organic amines and other alkaline complexing agents and pH regulators are required. The preparation process is cumbersome, time-consuming, and difficult to control. It is easy to cause excessive carrier wear rate and aggravate the loss of precious metal Pt.

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

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

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

[0009] In view of the above-mentioned problems, the present invention intends to provide a cyclohexane dehydrogenation catalyst with high activity, high stability, high conversion rate and high yield, and a preparation method and application thereof. The catalyst is used for dehydrogenating cyclohexane to obtain high-purity benzene and hydrogen, thereby improving the utilization rate of raw materials in the device and reducing production costs.

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

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

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

[0013] Alkaline earth metals are used in patents CN106693993A, CN110882703A and some prior arts, but the effect is not very good, and the benzene yield is only 84.3%. The inventor has tried the methods involved in various patents and prepared different catalysts by adding different alkaline earth metals (such as magnesium, calcium, strontium, and barium), but there are many problems, such as low cyclohexane conversion rate, low benzene yield, or the need for a high loading of active component Pt. The inventor tried to match 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 under a certain ratio increased significantly, and the highest can reach 99.99% and 99.9% respectively.

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

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

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

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

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

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

[0020] In some specific embodiments of the present invention, the auxiliary agent is selected from soluble salts such as nitrates, chlorides, carbonates, sulfates, ammonium salts, etc. The selection of soluble salts of these auxiliary agent components is conducive to the preparation of the auxiliary agent impregnation solution.

[0021] In some specific embodiments of the present invention, the soluble salts of rare earth metals and alkaline earth metals are nitrates.

[0022] The present invention provides a method for preparing a cyclohexane dehydrogenation catalyst, comprising the following steps:

[0023] (1) preparing an alumina carrier;

[0024] (2) impregnation of active components and additives;

[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: sodium aluminate or sodium aluminate solution is contacted with one or more of aluminum sulfate, aluminum nitrate, aluminum chloride, nitric acid and sulfuric acid solutions to carry out a gelation reaction. The gelation reaction can be carried out in a continuous manner, and the aluminum hydroxide obtained is aged, and the solid and liquid are separated, washed, dried and roasted to obtain a solid product; wherein the pH value of the primary gelation reaction is 6 to 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 solutions can be any possible concentration, as long as the pH value of the primary gelling reaction is 6 to 9.5. To ensure efficient preparation of pseudo-boehmite, the concentration of the sodium metaaluminate or sodium aluminate solution is preferably 30 to 300 g of aluminum oxide per liter, the concentration of aluminum sulfate, aluminum nitrate and aluminum chloride is preferably 10 to 120 g of aluminum oxide per liter, and the concentration of the nitric acid and sulfuric acid solutions is preferably 5 to 15 weight percent.

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

[0029] The solid-liquid separation method may be a conventional method, such as a filtration method or a centrifugal separation method.

[0030] The washing is carried out in a conventional manner, and the purpose of washing is to remove impurity ions, such as sulfate ions, sodium ions, etc. The washing should ensure that the content of alkali metal oxides in the formed aluminum oxide is not more than 0.15% by weight, and the content of sulfate ions is not more than 2% by weight.

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

[0032] The drying conditions are conventional drying conditions, and the drying temperature can be from room temperature to below the pseudo-boehmite crystal transformation temperature, preferably 60 to 200°C.

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

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

[0035] The concentration of the sodium aluminate or sodium aluminate solution can be any possible concentration. To ensure efficient preparation of pseudo-boehmite, the concentration of the sodium aluminate or sodium aluminate solution is preferably 5 to 200 g of aluminum oxide per liter, more preferably 5 to 120 g of aluminum oxide per liter.

[0036] The carbon dioxide-containing gas may be pure carbon dioxide gas, or a mixed gas consisting of carbon dioxide and an inert gas that does not affect the reaction, such as a mixed gas of carbon dioxide and one or more of air, nitrogen, helium, argon, etc. The carbon dioxide content in the carbon dioxide-containing gas may vary within a wide range. Generally, the carbon dioxide content is not less than 5% by volume, preferably not less than 20% by volume.

[0037] The gelling reaction can be intermittent. When this method is adopted, firstly, sodium aluminate or sodium aluminate solution is placed in a gelling tank, and a gas containing carbon dioxide is introduced from the bottom of the tank. The reaction temperature is controlled at 10-100°C, preferably 10-80°C, and the end point pH value is controlled at 6-9.5, preferably 6.5-9.3. By adjusting the concentration, dosage of sodium aluminate or sodium aluminate solution and the concentration and flow of carbon dioxide-containing gas, the gelling reaction time does not exceed 40 minutes, preferably does not exceed 30 minutes. After the gelling reaction is completed, an alkaline substance is quickly added to quickly increase the pH value of the slurry to above 9.5, preferably between 9.5 and 11.5, or solid-liquid separation and washing are quickly performed. Then, it is aged, filtered, washed and dried under normal conditions to obtain pseudo-boehmite, which is calcined to form an alumina carrier.

[0038] The gelling reaction can also be continuous. When this gelling method is adopted, first, deionized water is added to a gelling tank in advance, and a gas containing carbon dioxide is introduced from the bottom of the tank and a sodium aluminate or sodium aluminate solution is introduced from the top of the tank, so that the sodium aluminate or sodium aluminate solution is in countercurrent contact with the gas containing carbon dioxide, and the gelling temperature is controlled to be 10-100°C, preferably 10-80°C, and the concentration and flow rate of the sodium aluminate or sodium aluminate solution and the concentration and flow rate of the carbon dioxide-containing gas are controlled to make the pH value of the gelling process between 6 and 9.5, preferably between 6.5 and 9.3, and the residence time is not more than 40 minutes, preferably not more than 30 minutes. The slurry generated in the gelling process is continuously or intermittently collected in an aging tank, and alkaline substances are continuously or intermittently added to raise the pH value of the slurry to above 9.5, preferably between 9.5 and 11.5. After collecting for a period of time, the slurry generated by the gelling reaction is switched to another aging tank, and the slurry with a pH value greater than 9.5 in the first aging tank is aged, filtered, washed and dried to obtain pseudo-boehmite, which is then calcined to obtain an alumina carrier.

[0039] The alkaline substance is selected from one or more of inorganic bases, organic bases and their aqueous solutions. The inorganic base is preferably one or more of alkali metal hydroxides, aluminates, carbonates, bicarbonates, ammonium carbonate, ammonia water and their aqueous solutions. The organic base is preferably one or more of water-soluble amines, urea, pyridine and their aqueous solutions, preferably one or more of water-soluble aliphatic amines, alkyl ammonium hydroxides, urea, pyridine and their aqueous solutions, especially one or more of methylamine, ethylamine, propylamine, propylenediamine, various isomers of butylamine, various isomers of pentylamine, tetraethylammonium hydroxide, urea, pyridine and their aqueous solutions.

[0040] The solid-liquid separation method can be a filtration method or a centrifugal separation method. The washing after rapid solid-liquid separation is to remove the reactant sodium bicarbonate that can generate dawsonite, and is generally washed at least once with deionized water that is not less than 10 times the weight of the solid product.

[0041] The aging is carried out under conventional conditions, generally at a temperature of 5 to 100°C, preferably 30 to 100°C, more preferably 50 to 100°C, and for a time of more than 0.5 hours, preferably 1 to 8 hours. When the method of adding alkaline substances to adjust the pH value is adopted, the aging medium can be mother liquor or deionized water. When the method of rapid solid-liquid separation is adopted, the aging medium is generally deionized water.

[0042] The washing after aging is carried out in a conventional manner, and the purpose of washing is to remove impurity ions so that the content of alkali metal oxides is less than 0.15% by weight.

[0043] The drying conditions are conventional drying conditions, and the drying temperature can be from room temperature to below the pseudo-boehmite crystal transformation temperature, preferably 100-200°C.

[0044] When preparing the alumina support, it is also possible and preferred to carry out a shaping step as described above before drying.

[0045] The calcination conditions are conventional calcination conditions, such as a calcination temperature of 500 to 900° C., preferably 550 to 850° C., and a calcination time of 2 to 8 hours, preferably 3 to 6 hours.

[0046] In some specific embodiments of the present invention, the method for preparing alumina is: mixing sodium aluminate and aluminum sulfate solution, maintaining the pH value in the range of 8.5 to 9.5, filtering, washing, drying and calcining after the gelling reaction to obtain the alumina carrier.

[0047] In some specific embodiments of the present invention, after the impregnation in step (2), the carrier is placed in a rotary evaporation bottle and rotated at 1 to 6 r / min for 20 to 40 minutes to evaporate excess water by vacuum. After the surface of the carrier is dry, the carrier is taken out and the subsequent drying step is performed.

[0048] In some specific embodiments of the present invention, in step (3), the drying temperature is 60° C. to 100° C., and the drying time is 5 to 8 hours.

[0049] In the present invention, the drying temperature is any value among 60°C, 70°C, 80°C, 90°C, 100°C, or a range value between any two thereof; the drying time is any value among 5h, 6h, 7h, 8h, or a range value between any two thereof.

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

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

[0052] The present invention provides a method for preparing benzene by dehydrogenating cyclohexane, comprising the following steps: catalyzing the dehydrogenation reaction of cyclohexane with the cyclohexane dehydrogenation catalyst at a cyclohexane space velocity of 2.0-5.0h -1 The reaction was carried out under the conditions of a hydrogen flow rate of 5-15 mL / min, a reaction temperature of 400-450° C., and a hydrogen pressure of 0.2-0.6 MPa to obtain a product, which was analyzed by gas chromatography.

[0053] In the present invention, the mass space velocity of cyclohexane is 2h -1 , 3h -1 , 4h -1 , 5h -1 Any value in or any range between them.

[0054] In the present invention, the hydrogen flow rate is any value of 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 invention, the reaction temperature is any value among 420°C, 430°C, 440°C, 450°C, or any range between two of them.

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

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

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

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

[0060] (1) The catalyst provided by the present invention can be used for the dehydrogenation reaction of cyclohexane 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 invention is simple, efficient, and environmentally friendly, reduces the loss of precious metals, and has a small amount of carbon deposits;

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

[0063] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] Example 1

[0065] Preparation of vector:

[0066] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0067] Preparation of catalyst:

[0068] Take 97.6g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 2.31g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst A.

[0069] Example 2

[0070] The preparation of the carrier (same as in Example 1) is as follows:

[0071] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0072] Preparation of catalyst:

[0073] Take 97.7g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 2.10g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst B.

[0074] Example 3

[0075] The preparation of the carrier (same as in Example 1) is as follows:

[0076] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0077] Preparation of catalyst:

[0078] Take 97.8g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst C.

[0079] Example 4

[0080] The preparation of the carrier (same as in Example 1) is as follows:

[0081] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0082] Preparation of catalyst:

[0083] Take 97.9g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.68g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait until the surface of the carrier is dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst D.

[0084] Example 5

[0085] The preparation of the carrier (same as in Example 1) is as follows:

[0086] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0087] Preparation of catalyst:

[0088] Take 98.0g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.47g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst E.

[0089] Example 6

[0090] The preparation of the carrier (same as in Example 1) is as follows:

[0091] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0092] Preparation of catalyst:

[0093] Take 98.1g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.26g of chloroplatinic acid, 0.57g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait until the surface of the carrier is dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst F.

[0094] Example 7

[0095] The preparation of the carrier (same as in Example 1) is as follows:

[0096] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0097] Preparation of catalyst:

[0098] Take 97.8g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.57g of barium nitrate and 2.472g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst G.

[0099] Example 8

[0100] The preparation of the carrier (same as in Example 1) is as follows:

[0101] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0102] Preparation of catalyst:

[0103] Take 98.1g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.57g of barium nitrate and 2.781g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait until the surface of the carrier is dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst H.

[0104] Example 9

[0105] The preparation of the carrier (same as in Example 1) is as follows:

[0106] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0107] Preparation of catalyst:

[0108] Take 97.7g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.381g of barium nitrate and 3.399g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst I.

[0109] Example 10

[0110] The preparation of the carrier (same as in Example 1) is as follows:

[0111] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0112] Preparation of catalyst:

[0113] Take 97.9g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.381g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst J.

[0114] Embodiment 11

[0115] The preparation of the carrier (same as in Example 1) is as follows:

[0116] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0117] Preparation of catalyst:

[0118] Take 97.85g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.476g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst K.

[0119] Example 12

[0120] The preparation of the carrier (same as in Example 1) is as follows:

[0121] Add 2 liters of water to the gelling tank, and add sodium aluminate solution (Na2O 150g / L, Al2O3 100g / L) and aluminum sulfate solution (Al2O3 90g / L) while stirring. Control the dropping speed of sodium aluminate solution and aluminum sulfate solution respectively to keep the pH of the material in the range of 8.5-9.5. Add about 0.9 liters of sodium aluminate and 0.82 liters of aluminum sulfate. After filtering and washing with water, add 13 ml of dilute nitric acid (1:1 volume) and acidify for 1 hour, then slurry with 0.3 liters of water to form a sol. Use the oil column molding method to drip into the oil ammonia column to form a small spherical blank, and solidify in the ammonia water column for 2 hours, then filter, wash three times with deionized water, dry at 60°C for 6 hours, dry at 120°C for 2 hours, and roast at 500°C in a flowing air atmosphere for 4 hours to obtain an alumina ball carrier.

[0122] Preparation of catalyst:

[0123] Take 97.75g of the alumina ball carrier prepared above and put it into a rotary evaporator, evacuate it for 2h, dissolve 1.89g of chloroplatinic acid, 0.667g of barium nitrate and 3.09g of yttrium nitrate in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait for the surface of the carrier to dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain catalyst L.

[0124] Comparative Example 1

[0125] Take 98.8g of the carrier prepared in Example 1 and put it in a rotary evaporator. Vacuum it for 2h, dissolve 1.89g of chloroplatinic acid in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait until the surface of the carrier is dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain contrast agent A.

[0126] Comparative Example 2

[0127] Take 98.9g of the carrier prepared in Example 1 and put it into a rotary evaporator. Vacuum it for 2h, dissolve 1.68g of chloroplatinic acid in 120g of water to prepare a solution, and soak the solution in the rotary evaporator with the carrier at 2r / min for 30min. Vacuum evaporate excess water, wait until the surface of the carrier is dry, take it out, and then dry it at 80℃ for 6h, and calcine it at 600℃ for 8h to obtain contrast agent B.

[0128] Test Example 1

[0129] In Examples 1-12 and Comparative Examples 1-2, the catalyst was evaluated by the following method: the prepared catalyst was placed in a fixed bed reactor, cyclohexane was pumped into the fixed bed reactor through a feed pump, and the mass space velocity was 4h -1 , hydrogen enters the fixed bed reactor through a gas flow meter, the hydrogen flow rate is 10mL / min, the reaction is carried out at 420-450℃ and the reaction pressure is 0.28-0.35MPa, samples are taken regularly during the reaction, and the composition of the product is analyzed by gas chromatography. The content of Pt, Ba, Y and C in the catalyst is 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]

[0132]

[0133] Table 2 Catalyst performance

[0134] catalyst Cyclohexane conversion % Benzene yield% Catalyst A 99.98 99.23 Catalyst B 99.98 99.55 Catalyst C 99.99 99.98 Catalyst D 99.99 99.74 Catalyst E 99.76 98.91 Catalyst F 99.63 98.32 Catalyst G 99.86 99.75 Catalyst H 99.56 99.65 Catalyst I 99.81 99.75 Catalyst J 99.42 99.65 Catalyst K 99.65 99.46 Catalyst L 99.56 99.67 Contrast A 98.96 97.60 Contrast agent B 97.57 96.80

[0135] From the data in Table 1 and Table 2, it can be seen that after adding rare earth metal yttrium and alkaline earth metal barium, the cyclohexane conversion rate and benzene yield are significantly improved. When the Pt content is 0.896%, the Ba content is 0.299% and the Y content is 0.993, the cyclohexane conversion rate can reach 99.99%, the benzene yield can reach 99.98%, and the carbon deposition amount is 1.89%. In addition, when the Pt content is reduced to 0.601, the cyclohexane conversion rate can still be maintained at more than 99.6%, the benzene yield is more than 98%, and the carbon deposition amount is 1.76%.

[0136] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

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

2. The cyclohexane dehydrogenation catalyst according to claim 1, characterized in that 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 according to claim 1, characterized in that The alkaline earth metal is selected from magnesium, calcium, strontium and barium; further, the alkaline earth metal is barium.

4. The cyclohexane dehydrogenation catalyst according to claim 1, characterized in that Based on the weight of the catalyst, the content of the rare earth metal is 0.1-1.5%; further, the content of the rare earth metal is 0.1-1.0%.

5. The cyclohexane dehydrogenation catalyst according to claim 1, characterized in that Based on the weight of the catalyst, the content of the alkaline earth metal is 0.1-0.5%; further, the content of the alkaline earth metal is 0.2-0.4%.

6. The method for preparing the cyclohexane dehydrogenation catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) preparing an alumina carrier; (2) impregnation of active components and additives; (3) drying and calcining to obtain the cyclohexane dehydrogenation catalyst.

7. The method for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized in that: The preparation method of the alumina carrier is as follows: sodium aluminate or sodium aluminate solution is contacted with one or more of aluminum sulfate, aluminum nitrate, aluminum chloride, nitric acid and sulfuric acid solutions to react, and the obtained aluminum hydroxide is aged, and the solid and liquid are separated, washed, dried and calcined to obtain the alumina carrier.

8. The method for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized in that: In step (3), the drying temperature is 60° C. to 100° C., and the drying time is 5 to 8 hours.

9. The method for preparing a cyclohexane dehydrogenation catalyst according to claim 6, characterized in that: In step (3), the calcination temperature is 550-650° C. and the calcination time is 6-10 hours.

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

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