WO2025102756A1 - 一种丙烷脱氢催化剂及其制备方法和应用 - Google Patents

一种丙烷脱氢催化剂及其制备方法和应用 Download PDF

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WO2025102756A1
WO2025102756A1 PCT/CN2024/102869 CN2024102869W WO2025102756A1 WO 2025102756 A1 WO2025102756 A1 WO 2025102756A1 CN 2024102869 W CN2024102869 W CN 2024102869W WO 2025102756 A1 WO2025102756 A1 WO 2025102756A1
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cobalt
molecular sieve
preparation
propane dehydrogenation
hydrogen
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French (fr)
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张鹏
宋卫余
刘坚
黎安慧
武国强
吕雉
鲁玉莹
韩晓琳
王宗宝
肖海成
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Petrochina Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/035—Microporous crystalline materials not having base exchange properties, such as silica polymorphs, e.g. silicalites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/30—Ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C11/00—Aliphatic unsaturated hydrocarbons
    • C07C11/02—Alkenes
    • C07C11/06—Propene
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the invention relates to a propane dehydrogenation catalyst and a preparation method and application thereof, belonging to the technical field of petrochemical industry.
  • propylene As the basic raw material for many organic chemical products, propylene is widely used in various fields such as rubber, medicine and textiles.
  • PDH Propane dehydrogenation to propylene technology
  • Propane dehydrogenation is a strong endothermic reaction and needs to be carried out under high temperature conditions.
  • high reaction temperatures can easily cause deep dehydrogenation and cracking of propylene, which not only reduces the propylene yield but also causes carbon deposition and deactivation of the catalyst. Therefore, it is necessary to develop a propane dehydrogenation catalyst with high activity, high selectivity and strong stability.
  • the propane dehydrogenation catalysts used in industry are mainly Pt-based and Cr-based catalysts.
  • the precious metal Pt is expensive, and the high price of Cr is toxic to the human body and the environment.
  • the transition metal Co is abundant and non-toxic. Studies have found that the molecular sieve catalyst synthesized with metal Co as the active phase has good propane dehydrogenation reaction activity, and the four-coordinated Co 2+ can effectively activate the propane CH bond to generate propylene and hydrogen.
  • the catalyst loaded with Co by the impregnation method using traditional microporous, mesoporous or macroporous molecular sieves as carriers faces problems such as unclear catalytic active sites, poor metal dispersion, and easy sintering and carbon deposition leading to rapid catalyst deactivation.
  • the carrier has a crucial influence on catalytic activity and stability.
  • the components of traditional molecular sieves are relatively simple: the intrinsic pores of microporous molecular sieves are narrow, which limits the substrate transmission and easily causes carbon deposition and deactivation of the catalyst; it is difficult to anchor the active components in mesoporous or macroporous molecular sieves, and it is impossible to avoid sintering of active sites.
  • a large number of studies are focused on the method of introducing mesopores into microporous molecular sieve crystals to prepare multi-level pore molecular sieves with at least two pores (intrinsic micropore channels and mesopores).
  • multi-level pore molecular sieves can not only improve the carbon holding capacity of the carrier due to their mesopores, but also the multi-level pores are conducive to the mass transfer of substrates and products, thereby inhibiting carbon deposition, effectively improving the activity and stability of propane dehydrogenation catalysts.
  • an object of the present invention is to provide a propane dehydrogenation catalyst.
  • Another object of the present invention is to provide a method for preparing the above-mentioned propane dehydrogenation catalyst.
  • Another object of the present invention is to provide the use of the above propane dehydrogenation catalyst in the dehydrogenation of propane to propylene.
  • the present invention provides a propane dehydrogenation catalyst, wherein the propane dehydrogenation catalyst comprises a hydrogen-type mesoporous composite multi-level porous molecular sieve carrier and a cobalt active component, wherein a portion of the cobalt active component is loaded on the surface of the hydrogen-type mesoporous composite multi-level porous molecular sieve carrier in the form of CoO nanoparticles, and another portion of the cobalt active component enters the skeleton of the hydrogen-type mesoporous composite multi-level porous molecular sieve carrier in the form of forming chemical bonds and forms a Co 2+ -O-Si structure;
  • the content of the cobalt active component in terms of cobalt element is 0.1-7wt%.
  • the molar ratio of divalent cobalt to trivalent cobalt in the propane dehydrogenation catalyst is greater than 3.
  • the present invention provides a method for preparing the above-mentioned propane dehydrogenation catalyst, wherein the preparation method comprises the following steps:
  • Step (1) using an alkali treatment solution to treat pure silicon molecular sieve Silicalite-1, and then subjecting the alkali treatment product to ion exchange with an ammonium salt, and then drying and calcining the ion exchange product to obtain a hydrogen-type mesoporous and microporous composite multi-level pore molecular sieve;
  • Step (2) fully dissolving the cobalt salt and the hydrogen-type mesoporous composite multi-level porous molecular sieve in an ammonia solution, and adjusting the pH value of the system so that the cobalt ions are adsorbed on the surface of the hydrogen-type mesoporous composite multi-level porous molecular sieve and enter the cavities of its skeleton, and then drying and calcining the obtained solid precipitate to obtain the propane dehydrogenation catalyst.
  • pure silicon molecular sieve Silicalite-1 can be prepared by conventional methods.
  • pure silicon molecular sieve Silicalite-1 can be prepared by hydrothermal crystallization method.
  • the preparation method includes the following specific steps:
  • the silicon source, the structure directing agent and water are uniformly mixed to obtain a mixed solution, the mixed solution is hydrothermally crystallized, and the crystallized product is washed, dried and calcined to obtain the pure silicon molecular sieve Silicalite-1.
  • the silicon source includes one or a combination of tetraethyl orthosilicate, solid silica gel, white carbon black and silica sol
  • the structure directing agent includes one or a combination of tetrapropylammonium salts and/or tetraethylammonium salts such as tetrapropylammonium hydroxide (TPAOH), tetrapropylammonium chloride, tetraethylammonium hydroxide and tetraethylammonium chloride.
  • the molar ratio of the silicon source, the structure directing agent and water calculated as SiO2 is 1:(0.1-0.5):(5-50).
  • the hydrothermal crystallization temperature is 100-190° C., preferably 170° C., and the time is 24-96 h, preferably 72 h.
  • the alkaline treatment solution includes a sodium hydroxide aqueous solution, a tetrapropylammonium hydroxide aqueous solution or a tetraethylammonium hydroxide aqueous solution.
  • the concentration of the alkaline treatment solution is 0.01-1 mol/L, and the mass ratio of pure silicon molecular sieve Silicalite-1 to the alkaline treatment solution is 1:5-15.
  • the alkaline treatment solution is a sodium hydroxide aqueous solution
  • its concentration is 0.01-0.3 mol/L.
  • the temperature of the alkali treatment is room temperature-100°C, and the time is 1-6h.
  • step (1) further comprises washing the alkali-treated product to neutrality and then exchanging ions between the alkali-treated product and an ammonium salt.
  • the washing liquid used in the washing may be, for example, deionized water.
  • the temperature of ion exchange is not higher than 100° C.
  • ion exchange can be repeated multiple times to make the exchange more complete, and the ammonium salt used in ion exchange can be, for example, ammonium chloride.
  • the drying temperature is 60-120° C.
  • the present invention does not make specific requirements on the drying time, which can be reasonably determined according to the actual operation needs on site, as long as the purpose of drying the target product can be achieved.
  • step (1) and step (2) the calcination is carried out by heating the temperature from room temperature to 500-600°C at a heating rate of 0.5-5°C/min and keeping the temperature for 2-8h.
  • step (2) the pH value of the system is adjusted to 10.5-11.5.
  • step (2) specifically includes first dissolving the cobalt salt in an ammonia solution and then adjusting the pH value of the system to 10.5-11.5, then adding a hydrogen-type mesoporous composite multi-level pore molecular sieve and allowing it to fully dissolve and then adjusting the pH value of the system to 10.5-11.5 again, and then drying and calcining the obtained solid precipitate to obtain the propane dehydrogenation catalyst.
  • the pH value of the system in step (2), can be adjusted to 10.5-11.5 by adding ammonia water to the system.
  • the cobalt salt includes one or a combination of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt acetate, cobalt carbonyl, Co-EDTA complex and cobalt acetylacetonate complex.
  • the mass concentration of the ammonia solution is 1-2%.
  • step (2) further comprises centrifuging the solution obtained after adjusting the pH value of the system to 10.5-11.5, and then drying and calcining the solid precipitate obtained after the centrifugation.
  • the present invention first uses an alkali treatment liquid to perform alkali treatment and desiliconization on pure silicon molecular sieve Silicalite-1, and obtains a hydrogen-type mesoporous composite multi-level porous molecular sieve by adjusting the alkali treatment conditions, including the type of alkali, the treatment time, etc., and at the same time, the molecular sieve produces a large number of hydroxyl defects, and then adopts a strong electrostatic adsorption method to prepare a propane dehydrogenation catalyst.
  • the pH value of the system is accurately controlled to generate a strong electrostatic adsorption effect between the charged metal precursor ions and the molecular sieve carrier with opposite electrical properties, thereby forming a stable structure, preventing metal aggregation, forming highly dispersed nanoparticles, and realizing Co entering the molecular sieve framework to form a Co2 + -O-Si structure.
  • the present invention also provides use of the above-mentioned propane dehydrogenation catalyst in the dehydrogenation of propane to produce propylene.
  • the present invention uses an alkaline treatment solution to treat pure silicon molecular sieve Silicalite-1 to obtain a hydrogen-type mesoporous composite multi-level pore molecular sieve.
  • the multi-level pore structure in the hydrogen-type mesoporous composite multi-level pore molecular sieve is beneficial to the mass transfer between the substrate and the product, thereby inhibiting the generation of carbon deposition, and at the same time can improve the carbon holding capacity of the carrier, which is beneficial to improving the stability of the catalyst.
  • the catalyst is tested for stability for 12 hours, and the deactivation rate is only 0.033h -1 , which is better than the Co-based catalyst reported in the existing literature (J.Am.Chem.Soc.2022,144(27),12127-12137., J.Catal.2015,322,24-37. and ACS Applied Materials&Interfaces,2023,15(11):14250-14260., etc.).
  • the present invention uses a hydrogen-type mesoporous composite multi-level porous molecular sieve as a carrier and adopts a strong electrostatic adsorption method to prepare a propane dehydrogenation catalyst.
  • the propane dehydrogenation catalyst has the advantages of highly dispersed metals, small nanoparticles and high stability, while the active metal dispersion of the catalyst synthesized by the traditional impregnation method is low and it is easy to agglomerate and deactivate.
  • the strong electrostatic adsorption method used in the present invention does not require a high temperature and high pressure environment, thereby reducing environmental pollution and lowering production costs.
  • the propane dehydrogenation catalyst provided by the present invention uses a hydrogen-type mesoporous composite multi-level porous molecular sieve as a carrier, a part of the cobalt active component is loaded on the surface of the hydrogen-type mesoporous composite multi-level porous molecular sieve carrier in the form of CoO nanoparticles, and another part of the cobalt active component enters the skeleton of the hydrogen-type mesoporous composite multi-level porous molecular sieve carrier in the form of forming chemical bonds and forms a Co 2+ -O-Si structure, that is, the active site of the propane dehydrogenation catalyst is a four-coordinated Co 2+ , while the active site of the catalyst prepared by using pure silicon molecular sieve Silicalite-1 as a carrier and impregnating cobalt salt is Co 3 O 4 sites, this is because: 1) the surface of the hydrogen-type mesoporous composite multi-level pore molecular sieve carrier obtained after alkali
  • the catalyst provided by the present invention Compared with the Co 3 O 4 sites generated by impregnation with pure silicon molecular sieve Silicalite-1 as a carrier, the catalyst provided by the present invention has a more efficient propane dehydrogenation activity due to the presence of four-coordinated Co 2+ active sites, and the propane conversion rate can be increased by 40% under the same reaction conditions.
  • the propane dehydrogenation catalyst provided by the present invention has excellent catalytic propane dehydrogenation reaction activity and stability.
  • Figure 1a is a scanning electron micrograph of S-1.
  • Figure 1b is a scanning electron microscopy image of SN-0.05.
  • Figure 1c is a scanning electron microscope image of 0.5Co/S1.
  • Figure 1d is a scanning electron microscopy image of 0.5Co/SN-0.05.
  • Figure 1e is a transmission electron microscopy image of 0.5Co/SN-0.05
  • Figure 1f- Figure 1h are elemental surface scans of 0.5Co/SN-0.05.
  • Figure 1i- Figure 1k are elemental surface scans of 0.5Co/S1.
  • FIG2 is the X-ray diffraction (XRD) patterns of S-1, SN-0.05, 0.5Co/S1 and 0.5Co/SN-0.05.
  • FIG4 is the Raman spectra of 0.5Co/S1 and 0.5Co/SN-0.05.
  • FIG5 is the X-ray photoelectron spectra of 0.5Co/S1 and 0.5Co/SN-0.05.
  • FIG6 is a performance diagram of propane dehydrogenation reaction catalyzed by 0.5Co/S1 and 0.5Co/SN-0.05 catalysts.
  • FIG. 7 is a stability test diagram of propane dehydrogenation reaction catalyzed by 0.5Co/SN-0.05 catalyst.
  • FIG8 is a graph showing the regeneration performance of the 0.5Co/SN-0.05 catalyst for catalytic propane dehydrogenation reaction.
  • “Scope” disclosed in the present invention is given in the form of lower limit and upper limit. It can be one or more lower limits, and one or more upper limits respectively.
  • a given range is defined by selecting a lower limit and an upper limit.
  • the selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range.
  • a range of 60-120 and 80-110 is listed, and it is understood that a range of 60-110 and 80-120 is also expected.
  • the minimum range values listed are 1 and 2
  • the maximum range values listed are 3, 4 and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviation of any real number combination between a and b, where a and b are real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in the present invention, and "0-5" is just an abbreviation of these numerical combinations.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • This embodiment provides a propane dehydrogenation catalyst, which is prepared by a preparation method comprising the following specific steps:
  • Step 1 Weigh 22.5 g of deionized water and 19.5 g of TPAOH (25 wt%) and mix the two, then stir at a temperature of 50° C. and a rotation speed of 500 r/min for 10 min to mix the two uniformly to obtain a mixed solution;
  • Step 2 Weigh 12.5 g of TEOS and slowly add it to the above mixed solution, then stir at 50° C. for 6 h to obtain a mixture;
  • Step 3 The mixture was transferred into a 100 ml autoclave, and the autoclave was placed in an oven for hydrothermal crystallization, wherein the hydrothermal crystallization temperature was 170° C. and the crystallization time was 72 h;
  • Step 4 After the autoclave is cooled to room temperature, the slurry is taken out and centrifuged and washed with deionized water until the pH value is neutral.
  • Step 5 Place the centrifuged sample in an oven and dry it at 80°C for 12 hours, then calcine it at 550°C for 6 hours to obtain pure silicon molecular sieve Silicalite-1, recorded as S-1.
  • Step 6 Weigh 8 g of the above S-1, 80 g of deionized water and 0.16 g of NaOH and mix them, then stir at 50° C. for 3 h to obtain a slurry;
  • Step 7 Take out the slurry and centrifuge it, and wash the solid precipitate obtained by centrifugation with deionized water until it is neutral;
  • Step 8 Weigh 80g of deionized water and 2.14g of NH 4 Cl and mix them evenly to obtain an aqueous solution of ammonium chloride. Add the solid precipitate obtained in step 7 to the aqueous solution of ammonium chloride and stir at 90°C for 1h to perform ion exchange.
  • Step 9 Take out the slurry obtained in step 8 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until it is neutral, and repeat step 8 to perform ion exchange.
  • Step 10 Take out the slurry obtained in step 9 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until the pH value is neutral, and then place the obtained sample at 80°C for drying for 12 hours, and finally heat it from room temperature to 550°C at a heating rate of 2°C/min and calcine at this temperature for 4 hours to obtain a hydrogen-type mesoporous composite multi-level pore molecular sieve, denoted as SN-0.05, where "0.05" refers to the concentration of the sodium hydroxide aqueous solution used in this example, i.e. 0.05 mol/L.
  • This embodiment provides a propane dehydrogenation catalyst, which is prepared by a preparation method comprising the following specific steps:
  • Step 1 8 g of S-1 prepared in Example 1, 73.5 g of deionized water and 6.5 g of TPAOH were weighed and mixed, and then stirred at 50° C. for 3 h to obtain a slurry;
  • Step 2 Take out the slurry and centrifuge it, and wash the solid precipitate obtained by centrifugation with deionized water until it is neutral;
  • Step 3 Weigh 80g of deionized water and 2.14g of NH 4 Cl and mix them evenly to obtain an aqueous solution of ammonium chloride. Add the solid precipitate obtained in step 7 to the aqueous solution of ammonium chloride and stir at 90°C for 1h to perform ion exchange.
  • Step 4 Take out the slurry obtained in step 3 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until it is neutral, and repeat step 3 to perform ion exchange.
  • Step 5 Take out the slurry obtained in step 4 and centrifuge it. Use deionized water to wash the solid precipitate obtained by centrifugation until the pH value is neutral. Then place the obtained sample at 80°C for drying for 12 hours. Finally, heat it from room temperature to 550°C at a heating rate of 2°C/min and calcine it at this temperature for 4 hours to obtain a hydrogen-type mesoporous composite multi-level pore molecular sieve, denoted as SN-0.1, where "0.1" refers to the concentration of the TPAOH aqueous solution used in this embodiment, i.e. 0.1 mol/L.
  • This embodiment provides a propane dehydrogenation catalyst, which is prepared by a preparation method comprising the following specific steps:
  • This comparative example provides a propane dehydrogenation catalyst, which is prepared by a conventional impregnation method, and the preparation method comprises the following steps:
  • Step 1 Weigh 22.5 g of deionized water and 19.5 g of TPAOH (25 wt%) and mix the two, then stir at a temperature of 50° C. and a rotation speed of 500 r/min for 10 min to mix the two uniformly to obtain a mixed solution;
  • Step 2 Weigh 12.5 g of TEOS and slowly add it to the above mixed solution, then stir at 50° C. for 6 h to obtain a mixture;
  • Step 3 The mixture was transferred into a 100 ml autoclave, and the autoclave was placed in an oven for hydrothermal crystallization, wherein the hydrothermal crystallization temperature was 170° C. and the crystallization time was 72 h;
  • Step 4 After the autoclave is cooled to room temperature, the slurry is taken out and centrifuged and washed with deionized water until the pH value is neutral.
  • Step 5 Place the centrifuged sample in an oven and dry it at 80°C for 12 hours, then calcine it at 550°C for 6 hours to obtain pure silicon molecular sieve Silicalite-1, recorded as S-1.
  • Comparative Example 1 the preparation method of pure silicon molecular sieve Silicalite-1 is the same as that of Example 1.
  • Step 6 Weigh 1.5 g of the above S-1, 0.0370 g of cobalt nitrate hexahydrate and 1.5 g of deionized water, mix them and perform equal volume impregnation, and let stand overnight;
  • Step 7 Place the product obtained after the impregnation in step 6 in an oven and dry it at 80°C for 12 hours, and then calcine it at 550°C for 4 hours to obtain the propane dehydrogenation catalyst, recorded as 0.5Co/S1, with the total weight of S-1 being 100%, and the content of the cobalt active component in terms of cobalt element being 0.5wt%.
  • This comparative example provides a propane dehydrogenation catalyst, which is prepared by a conventional impregnation method, and the preparation method comprises the following steps:
  • Step 1 Weigh 22.5 g of deionized water and 19.5 g of TPAOH (25 wt%) and mix the two, then stir at a temperature of 50° C. and a rotation speed of 500 r/min for 10 min to mix the two uniformly to obtain a mixed solution;
  • Step 2 Weigh 12.5 g of TEOS and slowly add it to the above mixed solution, then stir at 50° C. for 6 h to obtain a mixture;
  • Step 3 The mixture was transferred into a 100 ml autoclave, and the autoclave was placed in an oven for hydrothermal crystallization, wherein the hydrothermal crystallization temperature was 170° C. and the crystallization time was 72 h;
  • Step 4 After the autoclave is cooled to room temperature, the slurry is taken out and centrifuged and washed with deionized water until the pH value is neutral.
  • Step 5 Place the centrifuged sample in an oven and dry it at 80°C for 12 hours, then calcine it at 550°C for 6 hours to obtain pure silicon molecular sieve Silicalite-1, recorded as S-1.
  • Step 6 Weigh 8 g of the above S-1, 80 g of deionized water and 0.16 g of NaOH and mix them, then stir at 50° C. for 3 h to obtain a slurry;
  • Step 7 Take out the slurry and centrifuge it, and wash the solid precipitate obtained by centrifugation with deionized water until it is neutral;
  • Step 8 Weigh 80g of deionized water and 2.14g of NH 4 Cl and mix them evenly to obtain an aqueous solution of ammonium chloride. Add the solid precipitate obtained in step 7 to the aqueous solution of ammonium chloride and stir at 90°C for 1h to perform ion exchange.
  • Step 9 Take out the slurry obtained in step 8 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until it is neutral, and repeat step 8 to perform ion exchange.
  • Step 10 Take out the slurry obtained in step 9 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until the pH value is neutral, and then place the obtained sample at 80°C for drying for 12 hours, and finally heat it from room temperature to 550°C at a heating rate of 2°C/min and calcine at this temperature for 4 hours to obtain a hydrogen-type mesoporous composite multi-level pore molecular sieve, denoted as SN-0.05, where "0.05" refers to the concentration of the sodium hydroxide aqueous solution used in this embodiment, i.e. 0.05 mol/L.
  • Comparative Example 1 the preparation method of the pure silicon molecular sieve Silicalite-1 and the hydrogen-type mesoporous composite multi-level pore molecular sieve is the same as that of Example 1.
  • Step 11 Weigh 1.5 g of the above SN-0.05, 0.0370 g of cobalt nitrate hexahydrate and 1.5 g of deionized water, mix them and perform equal volume impregnation, and let stand overnight;
  • Step 12 The product obtained after the impregnation in step 11 is placed in an oven and dried at 80° C. for 12 hours, and then calcined at 550° C. for 4 hours to obtain the propane dehydrogenation catalyst, recorded as D2-0.5Co/SN-0.05.
  • the total weight of SN-0.05 is 100%, and the content of the cobalt active component in terms of cobalt element is 0.5wt%.
  • This comparative example provides a propane dehydrogenation catalyst, which is prepared by a conventional impregnation method, and the preparation method comprises the following steps:
  • Step 1 Weigh 22.5 g of deionized water and 19.5 g of TPAOH (25 wt%) and mix the two, then stir at a temperature of 50° C. and a rotation speed of 500 r/min for 10 min to mix the two uniformly to obtain a mixed solution;
  • Step 2 Weigh 12.5 g of TEOS and slowly add it to the above mixed solution, then stir at 50° C. for 6 h to obtain a mixture;
  • Step 3 The mixture was transferred into a 100 ml autoclave, and the autoclave was placed in an oven for hydrothermal crystallization, wherein the hydrothermal crystallization temperature was 170° C. and the crystallization time was 72 h;
  • Step 4 After the autoclave is cooled to room temperature, the slurry is taken out and centrifuged and washed with deionized water until the pH value is neutral.
  • Step 5 Place the centrifuged sample in an oven and dry it at 80°C for 12 hours, then calcine it at 550°C for 6 hours to obtain pure silicon molecular sieve Silicalite-1, recorded as S-1.
  • Comparative Example 1 the preparation method of pure silicon molecular sieve Silicalite-1 is the same as that of Example 1.
  • Step 6 Weigh 0.0370 g of cobalt nitrate hexahydrate and stir it to dissolve in 3.7 mL of 1% ammonia solution, then adjust the pH value of the solution to 11 by dropping ammonia water, add 1.5 g of the above S-1 and stir until dissolved, adjust the pH value of the solution to 11 by dropping ammonia water again, continue stirring for 2 hours, centrifuge twice at 8000 r/min, 5 minutes each time, collect the solid and dry it at 80°C for 12 hours, finally heat it from room temperature to 550°C at a heating rate of 2°C/min and calcine at this temperature for 4 hours to obtain a propane dehydrogenation catalyst, recorded as D3-0.5Co/S1, based on the total weight of S-1 as 100%, the content of cobalt active component in terms of cobalt element is 0.5wt%.
  • This comparative example provides a propane dehydrogenation catalyst, which is prepared by a preparation method comprising the following specific steps:
  • the preparation of the hydrogen-type mesoporous composite multi-level pore molecular sieve is different from that of Example 1 in that the amount of NaOH used is different, including:
  • Step 7 Take out the slurry and centrifuge it, and wash the solid precipitate obtained by centrifugation with deionized water until it is neutral;
  • Step 8 Weigh 80g of deionized water and 2.14g of NH 4 Cl and mix them evenly to obtain an aqueous solution of ammonium chloride. Add the solid precipitate obtained in step 7 to the aqueous solution of ammonium chloride and stir at 90°C for 1h to perform ion exchange.
  • Step 9 Take out the slurry obtained in step 8 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until it is neutral, and repeat step 8 to perform ion exchange.
  • Step 10 Take out the slurry obtained in step 9 and centrifuge it, wash the solid precipitate obtained by centrifugation with deionized water until the pH value is neutral, and then place the obtained sample at 80°C for drying for 12 hours, and finally heat it from room temperature to 550°C at a heating rate of 2°C/min and calcine at this temperature for 4 hours to obtain a hydrogen-type mesoporous composite multi-level pore molecular sieve, denoted as SN-0.5, where "0.5" refers to the concentration of the sodium hydroxide aqueous solution used in this embodiment, i.e. 0.5 mol/L.
  • This comparative example provides a propane dehydrogenation catalyst, which is prepared by a preparation method comprising the following specific steps:
  • S-1 is in the shape of a flat hexagonal prism.
  • the basic morphology of the SN-0.05 sample obtained after alkali treatment of S-1 remains unchanged, but the edges of the prisms are obviously blurred, and unlike the smooth surface of S-1, the surface of the SN-0.05 sample is rough and has "gullies", as shown in Figure 1b.
  • Loading Co has no significant effect on the morphology of the S-1 and SN-0.05 samples, as shown in Figures 1d and 1e.
  • the surface Co species (should be CoO) of 0.5Co/SN-0.05 are small particles with relatively uniform size, which are highly dispersed on the hydrogen-type mesoporous composite multi-level porous molecular sieve carrier. No larger particles and agglomeration were found, which indicates that the surface Co species in the 0.5Co/SN-0.05 catalyst has better dispersion.
  • the Co species (should be Co 3 O 4 ) on the surface of 0.5Co/S1 is unevenly dispersed and has larger particle size.
  • both 0.5Co/S1 and 0.5Co/SN-0.05 have typical five-finger peaks belonging to the MFI skeleton structure, and no other impurity crystal peaks appear.
  • the diffraction peak heights of the two catalysts are basically the same, indicating that the loading of Co has no effect on the crystal structure of the carrier. No relevant diffraction peaks of Co species were detected in the two catalysts, indicating that the Co species are evenly distributed on the surface of the carrier.
  • New Raman bands appear at 465cm -1 , 593cm -1 and 680cm -1 for the 0.5Co/S1 catalyst, which are attributed to Co 3 O 4 species; a weaker asymmetric stretching vibration peak of the framework Co 2+ -O-Si appears at 1046cm -1 , because there are also some holes in S-1, and a small amount of Co will enter the framework after impregnation of the loaded cobalt salt; while the 0.5Co/SN-0.05 catalyst has stronger vibration peaks at 1046cm -1 and 1160cm -1 , which indicates that Co atoms are more bound to the molecular sieve framework in the 0.5Co/SN-0.05 catalyst.
  • 0.5Co/S1 and 0.5Co/SN-0.05 were analyzed by X-ray photoelectron spectroscopy, and the obtained X-ray photoelectron spectrum (XPS spectrum) is shown in Figure 5.
  • the 0.5Co/S1 catalyst shows two spin-orbit double peaks of Co 2+ and Co 3+ and their broad satellite peaks, of which the peak at 781.5eV belongs to Co 2+ , the peak at 780.0eV belongs to Co 3+ , and the Co 2+ /Co 3+ (the molar ratio of the two) is 1.51;
  • the 0.5Co/SN-0.05 catalyst also shows characteristic peaks corresponding to Co 2+ and Co 3+ , but the Co 2+ /Co 3+ (the molar ratio of the two) is 3.39.
  • the Co species in the 0.5Co/SN-0.05 catalyst mainly exists in the form of tetracoordinated Co 2+ , while the Co species in the 0.5Co/S1 catalyst are mostly
  • the catalyst was pressed into tablets and then ground and sieved, and the 40-60 mesh portion was taken.
  • the evaluation experiment was carried out on a continuous flow fixed bed reactor. Specifically, 0.2 g of the sieved catalyst was loaded into a quartz tube with an inner diameter of 6 mm. The temperature in the tube was programmed by a tubular resistance furnace and a temperature controller. The temperature was first programmed from room temperature to 580° C. in a nitrogen atmosphere. At 580° C., a H 2 /N 2 mixed gas containing 20 v% H 2 was introduced to reduce and activate the catalyst for 40 minutes at a total flow rate of 5 ml/min.
  • the catalyst regeneration method comprises: after the catalyst reacts for 2 hours according to the above process, air is introduced at a temperature of 580°C for calcination for 1 hour at a flow rate of 10 ml/min, then H2 / N2 mixed gas containing 20v% H2 is introduced for reduction activation for 40 minutes at a total flow rate of 5 ml/min, and then C3H8 / N2 mixed gas containing 5.04v% C3H8 is introduced for propane dehydrogenation to propylene reaction at a total flow rate of 10 ml/min, and after reacting for 10 minutes, online analysis is performed using a gas chromatograph. Thereafter, regeneration is performed every 2 hours of reaction.
  • the laboratory uses a Linghua 9890B gas chromatograph with a TCD detector.
  • the stability test diagram of the propane dehydrogenation reaction catalyzed by the 0.5Co/SN-0.05 catalyst is shown in Figure 7.
  • the initial conversion rate of the 0.5Co/SN-0.05 catalyst synthesized in Example 1 of the present invention is as high as 59%, and the selectivity is 98%.
  • the conversion rate is still maintained at 50%, the selectivity is still 98%, and the deactivation rate is 0.033h -1 , indicating that the 0.5Co/SN-0.05 catalyst has good reaction stability.
  • the regeneration test diagram of the propane dehydrogenation reaction catalyzed by the 0.5Co/SN-0.05 catalyst is shown in Figure 8.
  • the initial conversion rate of the 0.5Co/SN-0.05 catalyst synthesized in Example 1 of the present invention can still reach 58% after three regenerations, and the selectivity is 97%, which is equivalent to the activity of the fresh catalyst, indicating that the 0.5Co/SN-0.05 catalyst has good regeneration performance.
  • the average propane conversion rate of the 0.5Co/SN-0.05 catalyst prepared by the strong electrostatic adsorption method using the hydrogen-type mesoporous composite multi-level pore molecular sieve as the carrier in Example 1 of the present invention is significantly improved, and the average propylene selectivity is slightly improved; while compared with the D2-0.5Co/SN-0.05 catalyst prepared by the conventional impregnation method using the hydrogen-type mesoporous composite multi-level pore molecular sieve as the carrier in Comparative Example 2, the average propane conversion rate of the 0.5Co/SN-0.05 catalyst provided in Example 1 of the present invention is only slightly improved, and the average propylene selectivity is slightly improved.
  • the use of the hydrogen-type mesoporous composite multi-level pore molecular sieve obtained by alkali treatment as the catalyst carrier and the use of the strong electrostatic adsorption method to prepare the catalyst in the embodiments of the present invention can both improve the average propane conversion rate and the average propylene selectivity of the obtained catalyst, but the former contributes more to the improvement of the average propane conversion rate and the average propylene selectivity.

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Abstract

一种丙烷脱氢催化剂及其制备方法和应用，其中，所述丙烷脱氢催化剂包括氢型介微孔复合的多级孔分子筛载体和钴活性组分，其中一部分钴活性组分以CoO纳米颗粒的形式负载于氢型介微孔复合的多级孔分子筛载体的表面，另一部分钴活性组分以形成化学键的形式进入氢型介微孔复合的多级孔分子筛载体的骨架内并形成Co2+-O-Si结构；以氢型介微孔复合的多级孔分子筛载体的总重量为100％计，钴活性组分以钴元素计的含量为0.1-7wt％。该丙烷脱氢催化剂具有优异的催化丙烷脱氢反应活性和稳定性。

Description

一种丙烷脱氢催化剂及其制备方法和应用
本申请要求于2023年11月13日提交中国专利局、申请号为202311509026.4、发明名称为“一种丙烷脱氢催化剂及其制备方法和应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及一种丙烷脱氢催化剂及其制备方法和应用，属于石油化工技术领域。
背景技术
丙烯作为众多有机化工产品的基本原料，被广泛应用于橡胶、医药和纺织等各个领域。丙烷脱氢制丙烯技术(PDH)具有工艺流程短、丙烯选择性高、环境友好和综合成本低等优点，得到持续关注和发展。丙烷脱氢是一个强吸热反应，需要在高温条件下进行。但是较高的反应温度易造成丙烯的深度脱氢和裂解，既降低丙烯收率又导致催化剂积碳失活。因此需要开发一种高活性、高选择性且稳定性强的丙烷脱氢催化剂。
目前工业上使用的丙烷脱氢催化剂主要是Pt系和Cr系催化剂。然而贵金属Pt价格昂贵，高价Cr对人体和环境都有毒害作用。过渡金属Co储量丰富且无毒，有研究发现以金属Co为活性相合成的分子筛催化剂具有良好的丙烷脱氢反应活性，四配位的Co2+能有效活化丙烷C-H键生成丙烯和氢气。但是以传统微孔、中孔或大孔分子筛为载体通过浸渍法负载Co的催化剂面临催化活性位点不清晰，金属分散度差且易发生烧结、积碳导致催化剂快速失活等问题。
载体作为催化剂组成的基础，对催化活性和稳定性有至关重要的影响。传统的分子筛组成成分相对单一：微孔分子筛本征孔道狭窄，限制底物传输，易造成催化剂积碳失活；中孔或大孔分子筛难以锚定活性组分，无法避免活性位点烧结。目前，大量研究集中在将中孔引入到微孔分子筛晶体中的方法上，以制备具有至少两个孔隙(本征微孔孔道和中孔)的多级孔分子筛。与传统分子筛相比，多级孔分子筛由于具有中孔，不仅能够提高载体容碳能力，同时多级孔道也有利于底物及产物的传质从而抑制积碳，有效提高丙烷脱氢催化剂的活性及稳定性。
一直以来制备孤立的稳定Co基活性中心催化剂是研究难点。传统担载方式制备的金属负载分子筛易导致金属纳米粒子粒径不均匀，分散性差，活性位点不清楚，最终导致其催化性能也较差。目前本领域主要通过添加金属助剂来提高Co的分散性，但仍然存在丙烷转化率及丙烯选择性欠佳、催化活性差或催化剂稳定性差等问题。而以金属螯合物为原料制备的分子筛封装金属催化剂，可以实现将Co植入分子筛骨架，利用分子筛的内部微孔结构有效抑制金属粒子的聚集，进而提升其催化反应性能，但是存在催化剂原位合成过程中水热时间长、水热温度高、模版剂用量大、烧出模板剂会造成环境污染等缺陷。
因此，提供一种新型的丙烷脱氢催化剂及其制备方法和应用已经成为本领域亟需解决的技术问题。
发明内容
为了解决上述的缺点和不足，本发明的一个目的在于提供一种丙烷脱氢催化剂。
本发明的另一个目的还在于提供以上所述丙烷脱氢催化剂的制备方法。
本发明的又一个目的还在于提供以上所述丙烷脱氢催化剂在丙烷脱氢制丙烯中的应用。
为了实现以上目的，一方面，本发明提供了一种丙烷脱氢催化剂，其中，所述丙烷脱氢催化剂包括氢型介微孔复合的多级孔分子筛载体和钴活性组分，其中一部分钴活性组分以CoO纳米颗粒的形式负载于氢型介微孔复合的多级孔分子筛载体的表面，另一部分钴活性组分以形成化学键的形式进入氢型介微孔复合的多级孔分子筛载体的骨架内并形成Co2+-O-Si结构；
以氢型介微孔复合的多级孔分子筛载体的总重量为100％计，钴活性组分以钴元素计的含量为0.1-7wt％。
作为本发明以上所述丙烷脱氢催化剂的一具体实施方式，其中，丙烷脱氢催化剂中，二价钴和三价钴的摩尔比值大于3。
另一方面，本发明提供了以上所述丙烷脱氢催化剂的制备方法，其中，所述制备方法包括以下步骤：
步骤(1)：采用碱处理液对纯硅分子筛Silicalite-1进行碱处理后使碱处理产物与铵盐进行离子交换，再对离子交换后的产物进行干燥和焙烧，得到氢型介微孔复合的多级孔分子筛；
步骤(2)：将钴盐和氢型介微孔复合的多级孔分子筛充分溶解于氨水溶液中，并通过调节体系的pH值使钴离子吸附于氢型介微孔复合的多级孔分子筛的表面并进入其骨架的空穴中，再对所得固体沉淀进行干燥、焙烧，得到所述丙烷脱氢催化剂。
本发明以上所述制备方法中，纯硅分子筛Silicalite-1可以采用现有常规方法进行制备，例如在本发明的一些实施例中，可通过水热晶化法制备纯硅分子筛Silicalite-1，其制备方法包括以下具体步骤：
将硅源、结构导向剂和水混合均匀得到混合溶液，对所述混合溶液进行水热晶化，再对晶化产物进行洗涤、烘干和焙烧后得到所述纯硅分子筛Silicalite-1。
其中，所述硅源包括正硅酸四乙酯、固体硅胶、白炭黑和硅溶胶等中的一种或者几种的组合，所述结构导向剂包括四丙基氢氧化铵(TPAOH)、四丙基氯化铵、四乙基氢氧化铵和四乙基氯化铵等四丙基铵盐和/或四乙基铵盐中的一种或者几种的组合。
其中，以SiO2计的硅源、结构导向剂和水的摩尔比为1:(0.1-0.5):(5-50)。
其中，所述水热晶化的温度为100-190℃，优选为170℃，时间为24-96h，优选为72h。
作为本发明以上所述制备方法的一具体实施方式，其中，所述碱处理液包括氢氧化钠水溶液、四丙基氢氧化铵水溶液或四乙基氢氧化铵水溶液等。
作为本发明以上所述制备方法的一具体实施方式，其中，所述碱处理液的浓度为0.01-1mol/L，纯硅分子筛Silicalite-1与碱处理液的质量比为1:5-15。
作为本发明以上所述制备方法的一具体实施方式，其中，当所述碱处理液为氢氧化钠水溶液时，其浓度为0.01-0.3mol/L。
作为本发明以上所述制备方法的一具体实施方式，其中，所述碱处理的温度为常温-100℃，时间为1-6h。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(1)还包括将碱处理产物洗涤至中性后使碱处理产物与铵盐进行离子交换。其中，所述洗涤使用的洗涤液例如可为去离子水等。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(1)中，离子交换的温度不高于100℃。在本发明较为优选的实施方式中，可重复多次进行离子交换以使交换的更加充分，离子交换使用的铵盐例如可为氯化铵等。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(1)和步骤(2)中，所述干燥的温度为60-120℃。本发明对干燥的时间不做具体要求，可根据现场实际作业需要进行合理确定，只要保证可以实现将目标产物烘干的目的即可。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(1)和步骤(2)中，所述焙烧为以0.5-5℃/min的升温速率从室温升温至500-600℃，保温2-8h。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(2)中，调节体系的pH值为10.5-11.5。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(2)具体包括先将钴盐溶解于氨水溶液后调节体系pH值为10.5-11.5，然后加入氢型介微孔复合的多级孔分子筛并使其充分溶解后再次调节体系的pH值为10.5-11.5，再对所得固体沉淀进行干燥、焙烧，得到所述丙烷脱氢催化剂。
在本发明的一些实施例中，步骤(2)中可通过向体系中添加氨水以将其pH值调节为10.5-11.5。
作为本发明以上所述制备方法的一具体实施方式，其中，所述钴盐包括六水合硝酸钴、六水合氯化钴、乙酸钴、羰基钴、Co-EDTA配合物及乙酰丙酮钴配合物等中的一种或几种的组合
作为本发明以上所述制备方法的一具体实施方式，其中，所述氨水溶液的质量浓度1-2％。
作为本发明以上所述制备方法的一具体实施方式，其中，步骤(2)还包括先对再次调节体系的pH值为10.5-11.5后所得溶液进行离心，再对离心后所得固体沉淀进行干燥、焙烧。
本发明先采用碱处理液对纯硅分子筛Silicalite-1进行碱处理脱硅，并通过调变碱处理条件，包括碱种类，处理时间等制得氢型介微孔复合的多级孔分子筛，同时使得分子筛产生大量羟基缺陷，再采用强静电吸附法制备丙烷脱氢催化剂，在制备过程中精确控制体系的pH值，使带电金属前驱体离子与电性相反的分子筛载体之间产生强静电吸附作用，从而形成稳定的结构，防止金属聚集，形成高度分散的纳米颗粒，实现Co进入分子筛骨架形成Co2+-O-Si结构。
又一方面，本发明还提供了以上所述的丙烷脱氢催化剂在丙烷脱氢制丙烯中的应用。
与现有技术相比，本发明所能达成的有益技术效果包括：
(1)本发明采用碱处理液对纯硅分子筛Silicalite-1进行碱处理制得氢型介微孔复合的多级孔分子筛，与传统单一孔道的分子筛载体相比，该氢型介微孔复合的多级孔分子筛中的多级孔道结构有利于底物与产物的传质从而抑制积碳产生，同时还能提高载体容碳能力，有利于提高催化剂的稳定性，具体而言该催化剂经12h稳定性测试，失活速率仅为0.033h-1，相比于现有文献报道中的Co基催化剂(J.Am.Chem.Soc.2022,144(27),12127-12137.、J.Catal.2015,322,24-37.及ACS Applied Materials&Interfaces,2023,15(11):14250-14260.等)表现出更好的稳定性。
(2)本发明以氢型介微孔复合的多级孔分子筛为载体采用强静电吸附法制得丙烷脱氢催化剂，该丙烷脱氢催化剂具有金属高度分散、纳米颗粒小及稳定性高的优势，而采用传统浸渍法合成的催化剂的活性金属分散度低且容易团聚失活；与原位水热法合成相比，本发明采用的强静电吸附法无需高温高压环境，减少了环境污染，降低了生产成本。
(3)本发明提供的丙烷脱氢催化剂以氢型介微孔复合的多级孔分子筛为载体，一部分钴活性组分以CoO纳米颗粒的形式负载于氢型介微孔复合的多级孔分子筛载体的表面，另一部分钴活性组分以形成化学键的形式进入氢型介微孔复合的多级孔分子筛载体的骨架内并形成Co2+-O-Si结构，即该丙烷脱氢催化剂的活性位点为四配位Co2+，而以纯硅分子筛Silicalite-1为载体浸渍钴盐制得的催化剂的活性位点为Co3O4位点，这是因为：1)碱处理后制得的氢型介微孔复合的多级孔分子筛载体的表面具有大量缺陷位点，其能够很好地锚定Co物种，提高载体和金属组分之间的相互作用，从而可提高Co的分散程度，2)碱处理后制得的氢型介微孔复合的多级孔分子筛载体的骨架会形成空穴，采用强静电吸附法制备催化剂时Co原子成功以化学键方式结合到分子筛框架中形成四配位的Co2+；而未经碱处理的纯硅分子筛Silicalite-1的表面缺陷位和骨架中的空穴均较少，使得负载于载体表面的Co物种分散不均匀，颗粒尺寸较大，而且只有很少量的Co进入分子筛骨架，主要以Co3O4形式存在于分子筛表面。与以纯硅分子筛Silicalite-1为载体浸渍产生的Co3O4位点相比，本发明提供的催化剂由于具有四配位Co2+活性位点使其具有更高效的丙烷脱氢活性，相同反应条件下丙烷转化率可提高40％。
综上，本发明提供的丙烷脱氢催化剂具有优异的催化丙烷脱氢反应活性和稳定性。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1a为S-1的扫描电镜图。
图1b为SN-0.05的扫描电镜图。
图1c为0.5Co/S1的扫描电镜图。
图1d为0.5Co/SN-0.05的扫描电镜图。
图1e为0.5Co/SN-0.05的透射电镜图
图1f-图1h为0.5Co/SN-0.05的元素面扫图。
图1i-图1k为0.5Co/S1的元素面扫图。
图2为S-1、SN-0.05、0.5Co/S1及0.5Co/SN-0.05的X射线衍射(XRD)图谱。
图3为S-1、SN-0.05、0.5Co/S1及0.5Co/SN-0.05的N2物理吸附脱附等温线。
图4为0.5Co/S1及0.5Co/SN-0.05的拉曼光谱图。
图5为0.5Co/S1及0.5Co/SN-0.05的X射线光电子能谱图。
图6为0.5Co/S1及0.5Co/SN-0.05催化剂催化丙烷脱氢反应的性能图。
图7为0.5Co/SN-0.05催化剂催化丙烷脱氢反应的稳定性测试图。
图8为0.5Co/SN-0.05催化剂催化丙烷脱氢反应的再生性测试图。
具体实施方式
需要说明的是，本发明的说明书和权利要求书及上述附图中的术语“包括”以及其任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
本发明所公开的“范围”以下限和上限的形式给出。可以分别为一个或多个下限，和一个或多个上限。给定的范围是通过选定一个下限和一个上限进行限定的。选定的下限和上限限定了特别范围的边界。所有以这种方式进行限定的范围是可组合的，即任何下限可以与任何上限组合形成一个范围。例如，针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是可以预料到的。此外，如果列出的最小范围值为1和2，列出的最大范围值为3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。
在本发明中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本发明中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。
在本发明中，如果没有特别的说明，本发明所提到的所有实施方式以及优选实施方式可以相互组合形成新的技术方案。
在本发明中，如果没有特别的说明，本发明所提到的所有技术特征以及优选特征可以相互组合形成新的技术方案。
在本发明中，如果没有特别的说明，本文所提到的所有步骤可以顺序进行，也可以随机进行，但是优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可 以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附表、附图及实施例，对本发明进行进一步详细说明。下列所描述的实施例是本发明一部分实施例，而不是全部的实施例，仅用于说明本发明，而不应视为限制本发明的范围。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。实施例中未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
实施例1
本实施例提供了一种丙烷脱氢催化剂，其是采用包括如下具体步骤的制备方法制得的：
纯硅分子筛Silicalite-1的制备：
第1步：称取22.5g去离子水和19.5g的TPAOH(25wt％)并将二者混合，随后在温度为50℃、转速为500r/min的条件下搅拌10min以使二者混合均匀，得到混合液；
第2步：称取12.5g的TEOS，并将其缓慢加入上述混合液中，随后在50℃的温度条件下搅拌6h，得到混合物；
第3步：将上述混合物转移至100ml的高压釜内，并将高压釜置于烘箱中进行水热晶化，其中，水热晶化的温度为170℃，晶化时间为72h；
第4步：待高压釜冷却至室温后，取出浆液并依次进行离心、用去离子水洗涤至pH值为中性，
第5步：将离心后的样品置于烘箱中并于80℃烘干12h，再于550℃焙烧6h，得到纯硅分子筛Silicalite-1，记为S-1。
氢型介微孔复合的多级孔分子筛的制备：
第6步：称取8g上述S-1，80g去离子水及0.16gNaOH并将其混合，然后在50℃搅拌3h，得到浆液；
第7步：取出浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性；
第8步：称取80g去离子水，2.14gNH4Cl并将二者混合均匀得到氯化铵水溶液，将第7步所得固体沉淀加入氯化铵水溶液中并在90℃搅拌1h，以进行离子交换；
第9步：取出第8步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性，再重复步骤8进行离子交换。
第10步：取出第9步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至pH值为中性，再将所得样品置于80℃烘干12h，最后以2℃/min的升温速率从室温升 温至550℃并于该温度下焙烧4h，得到氢型介微孔复合的多级孔分子筛，记为SN-0.05，其中“0.05”是指本实施例中使用的氢氧化钠水溶液的浓度，即0.05mol/L。
丙烷脱氢催化剂的制备：
称取0.0370g的六水合硝酸钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为11，再加入1.5g上述SN-0.05搅拌直至溶解，再次通过滴加氨水调节溶液pH值为11，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，最后以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为0.5Co/SN-0.05，以SN-0.05的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
实施例2
本实施例提供了一种丙烷脱氢催化剂，其是采用包括如下具体步骤的制备方法制得的：
氢型介微孔复合的多级孔分子筛的制备：
第1步：称取8g实施例1制得的S-1，73.5g去离子水及6.5g的TPAOH并将其混合，然后在50℃搅拌3h，得到浆液；
第2步：取出浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性；
第3步：称取80g去离子水，2.14gNH4Cl并将二者混合均匀得到氯化铵水溶液，将第7步所得固体沉淀加入氯化铵水溶液中并在90℃搅拌1h，以进行离子交换；
第4步：取出第3步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性，再重复步骤3进行离子交换。
第5步：取出第4步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至pH值为中性，再将所得样品置于80℃烘干12h，最后以2℃/min的升温速率从室温升温至550℃并于该温度下焙烧4h，得到氢型介微孔复合的多级孔分子筛，记为SN-0.1，其中“0.1”是指本实施例中使用TPAOH水溶液的浓度，即0.1mol/L。
丙烷脱氢催化剂的制备：
称取0.0370g的六水合硝酸钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为11，再加入1.5g上述SN-0.1搅拌直至溶解，再次通过滴加氨水调节溶液pH值为11，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，最后以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为0.5Co/SN-0.1，以SN-0.1的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
实施例3
本实施例提供了一种丙烷脱氢催化剂，其是采用包括如下具体步骤的制备方法制得的：
称取0.0302g六水合氯化钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为10.5，再加入1.5g实施例1中制得的SN-0.05搅拌直至溶解，再次通过滴加氨水调节溶液pH值为10.5，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为C3-0.5Co/SN-0.05，以SN-0.05的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
对比例1
本对比例提供了一种丙烷脱氢催化剂，其是采用常规浸渍法制得的，制备方法包括以下步骤：
纯硅分子筛Silicalite-1的制备：
第1步：称取22.5g去离子水和19.5g的TPAOH(25wt％)并将二者混合，随后在温度为50℃、转速为500r/min的条件下搅拌10min以使二者混合均匀，得到混合液；
第2步：称取12.5g的TEOS，并将其缓慢加入上述混合液中，随后在50℃的温度条件下搅拌6h，得到混合物；
第3步：将上述混合物转移至100ml的高压釜内，并将高压釜置于烘箱中进行水热晶化，其中，水热晶化的温度为170℃，晶化时间为72h；
第4步：待高压釜冷却至室温后，取出浆液并依次进行离心、用去离子水洗涤至pH值为中性，
第5步：将离心后的样品置于烘箱中并于80℃烘干12h，再于550℃焙烧6h，得到纯硅分子筛Silicalite-1，记为S-1。
即对比例1中，纯硅分子筛Silicalite-1的制备方法与实施例1相同。
丙烷脱氢催化剂的制备：
第6步：称取1.5g上述S-1，0.0370g六水合硝酸钴及1.5g去离子水并将其混合后进行等体积浸渍，静置整夜；
第7步：将第6步浸渍后所得产品置于烘箱中并于80℃烘干12h，再于550℃焙烧4h，得到所述丙烷脱氢催化剂，记为0.5Co/S1，以S-1的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
对比例2
本对比例提供了一种丙烷脱氢催化剂，其是采用常规浸渍法制得的，制备方法包括以下步骤：
纯硅分子筛Silicalite-1的制备：
第1步：称取22.5g去离子水和19.5g的TPAOH(25wt％)并将二者混合，随后在温度为50℃、转速为500r/min的条件下搅拌10min以使二者混合均匀，得到混合液；
第2步：称取12.5g的TEOS，并将其缓慢加入上述混合液中，随后在50℃的温度条件下搅拌6h，得到混合物；
第3步：将上述混合物转移至100ml的高压釜内，并将高压釜置于烘箱中进行水热晶化，其中，水热晶化的温度为170℃，晶化时间为72h；
第4步：待高压釜冷却至室温后，取出浆液并依次进行离心、用去离子水洗涤至pH值为中性，
第5步：将离心后的样品置于烘箱中并于80℃烘干12h，再于550℃焙烧6h，得到纯硅分子筛Silicalite-1，记为S-1。
氢型介微孔复合的多级孔分子筛的制备：
第6步：称取8g上述S-1，80g去离子水及0.16gNaOH并将其混合，然后在50℃搅拌3h，得到浆液；
第7步：取出浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性；
第8步：称取80g去离子水，2.14gNH4Cl并将二者混合均匀得到氯化铵水溶液，将第7步所得固体沉淀加入氯化铵水溶液中并在90℃搅拌1h，以进行离子交换；
第9步：取出第8步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性，再重复步骤8进行离子交换。
第10步：取出第9步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至pH值为中性，再将所得样品置于80℃烘干12h，最后以2℃/min的升温速率从室温升温至550℃并于该温度下焙烧4h，得到氢型介微孔复合的多级孔分子筛，记为SN-0.05，其中“0.05”是指本实施例中使用的氢氧化钠水溶液的浓度，即0.05mol/L。
即对比例1中，纯硅分子筛Silicalite-1和氢型介微孔复合的多级孔分子筛的制备方法与实施例1相同。
丙烷脱氢催化剂的制备：
第11步：称取1.5g上述SN-0.05，0.0370g六水合硝酸钴及1.5g去离子水并将其混合后进行等体积浸渍，静置整夜；
第12步：将第11步浸渍后所得产品置于烘箱中并于80℃烘干12h，再于550℃焙烧4h，得到所述丙烷脱氢催化剂，记为D2-0.5Co/SN-0.05，以SN-0.05的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
对比例3
本对比例提供了一种丙烷脱氢催化剂，其是采用常规浸渍法制得的，制备方法包括以下步骤：
纯硅分子筛Silicalite-1的制备：
第1步：称取22.5g去离子水和19.5g的TPAOH(25wt％)并将二者混合，随后在温度为50℃、转速为500r/min的条件下搅拌10min以使二者混合均匀，得到混合液；
第2步：称取12.5g的TEOS，并将其缓慢加入上述混合液中，随后在50℃的温度条件下搅拌6h，得到混合物；
第3步：将上述混合物转移至100ml的高压釜内，并将高压釜置于烘箱中进行水热晶化，其中，水热晶化的温度为170℃，晶化时间为72h；
第4步：待高压釜冷却至室温后，取出浆液并依次进行离心、用去离子水洗涤至pH值为中性，
第5步：将离心后的样品置于烘箱中并于80℃烘干12h，再于550℃焙烧6h，得到纯硅分子筛Silicalite-1，记为S-1。
即对比例1中，纯硅分子筛Silicalite-1的制备方法与实施例1相同。
丙烷脱氢催化剂的制备：
第6步：称取0.0370g的六水合硝酸钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为11，再加入1.5g上述S-1搅拌直至溶解，再次通过滴加氨水调节溶液pH值为11，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，最后以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为D3-0.5Co/S1，以S-1的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
对比例4
本对比例提供了一种丙烷脱氢催化剂，其是采用包括如下具体步骤的制备方法制得的：
纯硅分子筛Silicalite-1的制备与实施例1相同；
氢型介微孔复合的多级孔分子筛的制备与实施例1的区别在于NaOH的用量不同，包括：
称取8g上述S-1，80g去离子水及1.6gNaOH并将其混合，然后在50℃搅拌3h，得到浆液；
第7步：取出浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性；
第8步：称取80g去离子水，2.14gNH4Cl并将二者混合均匀得到氯化铵水溶液，将第7步所得固体沉淀加入氯化铵水溶液中并在90℃搅拌1h，以进行离子交换；
第9步：取出第8步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至中性，再重复步骤8进行离子交换。
第10步：取出第9步所得浆液并离心，采用去离子水将离心所得固体沉淀洗涤至pH值为中性，再将所得样品置于80℃烘干12h，最后以2℃/min的升温速率从室温升温至550℃并于该温度下焙烧4h，得到氢型介微孔复合的多级孔分子筛，记为SN-0.5，其中“0.5”是指本实施例中使用的氢氧化钠水溶液的浓度，即0.5mol/L。
丙烷脱氢催化剂的制备：
称取0.0370g的六水合硝酸钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为11，再加入1.5g上述SN-0.5搅拌直至溶解，再次通过滴加氨水调节溶液pH值为11，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，最后以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为D4-0.5Co/SN-0.5，以SN-0.5的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
对比例5
本对比例提供了一种丙烷脱氢催化剂，其是采用包括如下具体步骤的制备方法制得的：
纯硅分子筛Silicalite-1和氢型介微孔复合的多级孔分子筛的制备与实施例1相同：
丙烷脱氢催化剂的制备：
称取0.0370g的六水合硝酸钴并将其搅拌溶解于3.7mL质量浓度为1％的氨水溶液中，然后通过滴加氨水调节溶液pH值为9，再加入1.5g实施例1制得的SN-0.05搅拌直至溶解，再次通过滴加氨水调节溶液pH值为9，继续搅拌2h后，于8000r/min离心2次，每次5min，收集固体并于80℃烘干12h后，最后以2℃/min的升温速率从室温升温至550℃并在该温度下焙烧4h，得到丙烷脱氢催化剂，记为D5-0.5Co/SN-0.05，以SN-0.05的总重量为100％计，钴活性组分以钴元素计的含量为0.5wt％。
表征测试例1
本表征测试例分别对S-1、SN-0.05、0.5Co/S1及0.5Co/SN-0.05进行扫描电镜分析，所得扫描电镜图分别如图1a-图1d所示；本测试例还对0.5Co/SN-0.05进行了透射电镜分析，并对0.5Co/S1及0.5Co/SN-0.05分别进行了EDS分析，0.5Co/SN-0.05的透射电镜图如图1e所示，0.5Co/SN-0.05的元素面扫图如图图1f-图1h所示，0.5Co/S1的元素面扫图如图1i-图1k所示。
从图1a可以看出，S-1呈扁平六棱柱形状，对S-1进行碱处理之后获得的SN-0.05样品的基本形貌不变，但是棱柱边缘明显模糊，并且与S-1光滑的表面不同，SN-0.05样品的表面粗糙，存在“沟壑”，如图1b所示，并且负载Co之后未对S-1和SN-0.05样品形貌产生重大影响，如图1d和图1e所示。
从图1e所示的透射电镜图中可以清晰看到，碱处理后获得的SN-0.05样品中存在的介孔结构。
从图1f-图1h可以看出，0.5Co/SN-0.05的表面Co物种(应为CoO)为尺寸较为均一的小颗粒，高度分散在氢型介微孔复合的多级孔分子筛载体上，并没有发现较大颗粒和团聚现象，这表明0.5Co/SN-0.05催化剂中表面Co物种分散度更好，而从图1i-图1k中可以看出，0.5Co/S1表面的Co物种(应为Co3O4)分散不均匀，颗粒尺寸较大。
表征测试例2
本表征测试例分别对S-1、SN-0.05、0.5Co/S1及0.5Co/SN-0.05进行X射线衍射分析，所得X射线衍射(XRD)图谱分别如图2所示。从图2中可以看出，S-1及碱处理后的SN-0.05分子筛在2θ＝22.5-25°之间出现了归属于MFI骨架结构的典型特征峰，并且没有其他杂晶峰的出现，说明制备的样品均为纯相S-1分子筛，取SN-0.05在2θ＝22.5-25°的面积为I，S-1在2θ＝22.5-25°的面积为I0，相对结晶度为(I/I0)×100％，设S-1的相对结晶度为100％。由计算结果可知，用0.05mol/L的NaOH碱液处理后的SN-0.05样品的结晶度较好，高90％。
从图2中还可以看出，0.5Co/S1及0.5Co/SN-0.05均出现典型的归属于MFI骨架结构的五指峰，并且没有其他杂晶峰的出现，两个催化剂衍射峰高度基本一致，说明负载Co之后对载体晶体结构没有影响。两个催化剂均没有检测出Co物种的相关衍射峰，说明Co物种在载体表面分布均匀。
表征测试例3
本表征测试例分别对S-1、SN-0.05、0.5Co/S1及0.5Co/SN-0.05进行N2物理吸附脱附等温测试，所得N2物理吸附脱附等温线如图3所示。从图3中可以看出，0.5Co/S1是典型的Ⅰ型吸附等温线，说明该催化剂使用的载体是传统的微孔分子筛，而0.5Co/SN-0.05的N2物理吸附脱附等温线中出现明显的回滞环，属于Ⅴ型吸附等温线，证明该催化剂所使用的载体呈多级孔状态。
表征测试例4
本表征测试例分别对0.5Co/S1及0.5Co/SN-0.05进行拉曼光谱图分析，所得拉曼光谱图如图4所示。从图4中可以看出，两个样品在约370cm-1和800cm-1处出现两个明显的吸附带，这对应于分子筛MFI拓扑结构。0.5Co/S1催化剂在465cm-1、593cm-1和680cm-1出现新的拉曼带，这归属于Co3O4物种；在1046cm-1处出现较弱的骨架Co2+-O-Si的不对称伸缩振动峰，这是因为S-1中也会有部分空穴，浸渍负载钴盐后也会有少量Co进入骨架内；而0.5Co/SN-0.05催化剂在1046cm-1和1160cm-1都出现了更强的振动峰，这表明在0.5Co/SN-0.05催化剂中Co原子更多地结合到分子筛骨架中。
表征测试例5
本表征测试例分别对0.5Co/S1及0.5Co/SN-0.05进行X射线光电子能谱分析，所得X射线光电子能谱图(XPS图谱)如图5所示。从图5中可以看出，0.5Co/S1催化剂显示了Co2+和Co3+的两个自旋轨道双峰及其宽的卫星峰，其中781.5eV处的峰归属于Co2+，780.0eV处的峰归属于Co3+，且Co2+/Co3+(二者的摩尔比)为1.51；0.5Co/SN-0.05催化剂同样显示出对应于Co2+和Co3+的特征峰，但其中Co2+/Co3+(二者的摩尔比)为3.39。这说明0.5Co/SN-0.05催化剂中Co物种主要以四配位Co2+形式存在，而0.5Co/S1催化剂中Co物种多为Co3O4物种。
催化剂性能评价实施例
本实施例分别对本发明实施例1-实施例3和对比例1-对比例提供的0.5Co/SN-0.05、0.5Co/SN-0.1、C3-0.5Co/SN-0.05、0.5Co/S1、D2-0.5Co/SN-0.05、D3-0.5Co/S1、D4-0.5Co/SN-0.5及D5-0.5Co/SN-0.05进行丙烷脱氢制丙烯性能评价，包括：
将催化剂压片后研磨过筛，取40-60目的部分，评价实验在连续流动的固定床反应器上进行，具体是将0.2g过筛后的催化剂装入到内径为6mm的石英管中，管内温度由管式电阻炉和控温仪进行程序升温控制，先在氮气气氛中由室温经过程序升温至580℃，在580℃的温度条件下通入含20v％H2的H2/N2混合气对催化剂还原活化40min，总流速为5ml/min，随后通入含5.04v％C3H8的C3H8/N2混合气进行丙烷脱氢制丙烯反应，总流速为10ml/min，待反应10min后用气相色谱仪在线分析。
催化剂的再生方法包括：待催化剂按照上述过程反应2h后，在580℃的温度条件下通入空气焙烧1h，流速为10ml/min，随后通入含20v％H2的H2/N2混合气还原活化40min，总流速为5ml/min，再通入含5.04v％C3H8的C3H8/N2混合气进行丙烷脱氢制丙烯反应，总流速为10ml/min，待反应10min后用气相色谱仪在线分析。之后每反应2h进行一次再生。
实验室所采用的是含有TCD检测器的灵华9890B气相色谱仪。
其中，0.5Co/S1及0.5Co/SN-0.05催化剂催化丙烷脱氢反应的性能图如图6所示。由该图6可知，相较于对比例1中制得的0.5Co/S1催化剂，本发明实施例1合成的0.5Co/SN-0.05催化剂表现出更高的催化性能。
0.5Co/SN-0.05催化剂催化丙烷脱氢反应的稳定性测试图如图7所示。由该图7可知，本发明实施例1合成的0.5Co/SN-0.05催化剂的初始转化率高达59％，选择性为98％，经12h稳定性测试后，转化率仍保持在50％，选择性仍为98％，失活速率为0.033h-1，表明该0.5Co/SN-0.05催化剂具有较好的反应稳定性。
0.5Co/SN-0.05催化剂催化丙烷脱氢反应的再生性测试图如图8所示。由该图8可知，本发明实施例1合成的0.5Co/SN-0.05催化剂再生三次后初始转化率仍能达到58％，选择性为97％，与新鲜催化剂活性相当，这表明该0.5Co/SN-0.05催化剂具有较好的再生性能。
本发明实施例1-实施例3和对比例1-对比例5提供的各催化剂的丙烷平均转化率和丙烯平均选择性数据如下表1所示。
表1
从表1中可以看出，相较于对比例1和对比例3中以纯硅分子筛Silicalite-1为载体，分别采用现有常规浸渍法和强静电吸附法制得的0.5Co/S1催化剂和D3-0.5Co/S1催化剂，本发明实施例1中以氢型介微孔复合的多级孔分子筛为载体，采用强静电吸附法制得的0.5Co/SN-0.05催化剂的丙烷平均转化率显著提高，丙烯平均选择性略有提高；而相较于对比例2中以氢型介微孔复合的多级孔分子筛为载体，采用现有常规浸渍法制得的D2-0.5Co/SN-0.05催化剂，本发明实施例1提供的0.5Co/SN-0.05催化剂的丙烷平均转化率仅有较小幅度的提高，丙烯平均选择性略有提高。
对比上述结果可知，本发明实施例中采用经碱处理制得的氢型介微孔复合的多级孔分子筛为催化剂载体和采用强静电吸附法制备催化剂均可以提高所得催化剂的丙烷平均转化率和丙烯平均选择性，但前者对丙烷平均转化率和丙烯平均选择性的提高贡献更大。
从表1中还可以看出，当碱处理使用的碱处理液为氢氧化钠水溶液时，本发明实施例1中采用浓度为0.05mol/L的氢氧化钠水溶液制得的催化剂的丙烷平均转化率和丙烯平均选择性分别高达57％和98％，而对比例4中采用浓度为0.5mol/L的氢氧化钠水溶液制得的催化剂的丙烷平均转化率和丙烯平均选择性仅分别为48％和95％，这说明碱处理使用的碱处理液的浓度会影响所制得的催化剂的活性和选择性，而且当碱处理液为氢氧化钠水溶液时，其浓度在0.01-0.3mol/L范围内才能实现本发明的目的并达成如上所示的有益技术效果；
从表1中还可以看出，对比例1采用强静电吸附法制备催化剂过程中体系的pH值仅为9，其制得的催化剂的丙烷平均转化率和丙烯平均选择性分别仅为53％和97％，而本发明实施例1采用强静电吸附法制备催化剂过程中体系的pH值控制为11，其所制得的催化剂的丙烷平均转化率和丙烯平均选择性均有所提高，分别可达到57％和98％，这说明强静电吸附法制备催化剂过程中体系的pH值也会影响所制得的催化剂的活性和选择性，当pH值在10.5-11.5范围内才能实现本发明的目的并达成如上所示的有益技术效果。
以上所述，仅为本发明的具体实施例，不能以其限定发明实施的范围，所以其等同组件的置换，或依本发明专利保护范围所作的等同变化与修饰，都应仍属于本专利涵盖的范畴。另外，本发明中的技术特征与技术特征之间、技术特征与技术发明之间、技术发明与技术发明之间均可以自由组合使用。

Claims (15)

  1. 一种丙烷脱氢催化剂，其特征在于，所述丙烷脱氢催化剂包括氢型介微孔复合的多级孔分子筛载体和钴活性组分，其中一部分钴活性组分以CoO纳米颗粒的形式负载于氢型介微孔复合的多级孔分子筛载体的表面，另一部分钴活性组分以形成化学键的形式进入氢型介微孔复合的多级孔分子筛载体的骨架内并形成Co2+-O-Si结构；
    以氢型介微孔复合的多级孔分子筛载体的总重量为100％计，钴活性组分以钴元素计的含量为0.1-7wt％。
  2. 根据权利要求1所述的丙烷脱氢催化剂，其特征在于，丙烷脱氢催化剂中，二价钴和三价钴的摩尔比值大于3。
  3. 权利要求1或2所述的丙烷脱氢催化剂的制备方法，其特征在于，所述制备方法包括：
    步骤(1)：采用碱处理液对纯硅分子筛Silicalite-1进行碱处理后使碱处理产物与铵盐进行离子交换，再对离子交换后的产物进行干燥和焙烧，得到氢型介微孔复合的多级孔分子筛；
    步骤(2)：将钴盐和氢型介微孔复合的多级孔分子筛充分溶解于氨水溶液中，并通过调节体系的pH值使钴离子吸附于氢型介微孔复合的多级孔分子筛的表面并进入其骨架的空穴中，再对所得固体沉淀进行干燥、焙烧，得到所述丙烷脱氢催化剂。
  4. 根据权利要求3所述的制备方法，其特征在于，所述碱处理液包括氢氧化钠水溶液、四丙基氢氧化铵水溶液或四乙基氢氧化铵水溶液。
  5. 根据权利要求3或4所述的制备方法，其特征在于，所述碱处理液的浓度为0.01-1mol/L，纯硅分子筛Silicalite-1与碱处理液的质量比为1:5-15。
  6. 根据权利要求5所述的制备方法，其特征在于，当所述碱处理液为氢氧化钠水溶液时，其浓度为0.01-0.3mol/L。
  7. 根据权利要求3或4所述的制备方法，其特征在于，所述碱处理的温度为常温-100℃，时间为1-6h。
  8. 根据权利要求3或4所述的制备方法，其特征在于，步骤(1)中，离子交换的温度不高于100℃。
  9. 根据权利要求3或4所述的制备方法，其特征在于，步骤(1)和步骤(2)中，所述干燥的温度为60-120℃。
  10. 根据权利要求3或4所述的制备方法，其特征在于，步骤(1)和步骤(2)中，所述焙烧为以0.5-5℃/min的升温速率从室温升温至500-600℃，保温2-8h。
  11. 根据权利要求3所述的制备方法，其特征在于，步骤(2)中，调节体系的pH值为10.5-11.5。
  12. 根据权利要求3或11所述的制备方法，其特征在于，步骤(2)具体包括先将钴盐溶解于氨水溶液后调节体系pH值为10.5-11.5，然后加入氢型介微孔复合的多级孔分子筛并使其充分溶解后再次调节体系的pH值为10.5-11.5，再对所得固体沉淀进行干燥、焙烧，得到所述丙烷脱氢催化剂。
  13. 根据权利要求3所述的制备方法，其特征在于，所述钴盐包括六水合硝酸钴、六水合氯化钴、乙酸钴、羰基钴、Co-EDTA配合物及乙酰丙酮钴配合物中的一种或几种的组合。
  14. 根据权利要求3或13所述的制备方法，其特征在于，所述氨水溶液的质量浓度1-2％。
  15. 权利要求1或2所述的丙烷脱氢催化剂在丙烷脱氢制丙烯中的应用。
PCT/CN2024/102869 2023-11-13 2024-07-01 一种丙烷脱氢催化剂及其制备方法和应用 Pending WO2025102756A1 (zh)

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