A light hydrocarbon conversion catalyst for producing propylene in high yield, a preparation method thereof, and use thereof

Abstract

A light hydrocarbon conversion catalyst for producing propylene, characterized in that the catalyst comprises a composite carrier and a Group VA element oxide supported on the composite carrier; the composite carrier contains 5-40 wt% of hydrogen type ZSM-48 zeolite, 5-30 wt% of hydrogen type ZSM-5 zeolite, 0.5-20 wt% of zirconium oxide and 10-89.5 wt% of aluminum oxide based on the composite carrier. The catalyst can obtain higher low-carbon olefin yield and aromatic hydrocarbon yield, especially extremely high propylene yield, while being stable in operation; the catalyst has strong carbon deposition resistance, long single-pass reaction cycle, and good regeneration performance suitable for multiple reaction and regeneration operations.

Description

Technical Field

[0001] This invention relates to catalysts, preparation methods, and applications thereof, and more specifically to light hydrocarbon conversion catalysts, preparation methods, and applications thereof. Background Technology

[0002] Light hydrocarbons generally refer to a mixture of low-carbon hydrocarbons (C4-C8) produced as a byproduct of petrochemical and coal processing. The main sources of light hydrocarbons include: C4-C8 hydrocarbons from atmospheric and vacuum distillation, catalytic cracking, and delayed coking units. 4+ Components, pyrolysis C in steam cracking unit 5+ The components include topping oil and residue oil from catalytic reforming, aromatics complex, and hydrotreating units, as well as naphtha and other by-products from coal-to-oil processes. Due to the extremely high vapor pressure of light hydrocarbon components, and with the further restrictions on vapor pressure imposed by new gasoline standards, these components can no longer be used for blending in gasoline pools, necessitating new high-value utilization pathways.

[0003] With the continuous expansion of crude oil and coal processing scale and the increasing depth of processing, low-value light hydrocarbon resources, mainly C4-C8, are becoming increasingly abundant. Converting them into high-value chemical products such as low-carbon olefins and aromatics can greatly improve the efficiency of light hydrocarbon utilization and is also of great significance for the transformation of refining and chemical enterprises towards the chemical industry. The following research reports have documented the simultaneous production of aromatics and light olefins from light hydrocarbons as raw materials.

[0004] CN1065901C first proposed a method for simultaneously converting non-aromatic hydrocarbons into aromatic hydrocarbons and olefins. It uses a zeolite catalyst modified with silicon, boron, phosphorus, and alkaline earth metals, as well as undergoing special post-treatment. This method reduces the coke formation rate while increasing the yield of aromatic hydrocarbons and light olefins in the aromatization process. In addition, in terms of process research, the partial pressure of reactants is reduced by adding an inert medium, which further improves the yield of light olefins.

[0005] CN1504541A discloses a catalyst and its application for catalytic cracking of hydrocarbons to produce olefins and co-produce aromatics. It uses a zeolite catalyst with a pore size of 0.45-0.7 nm modified by phosphorus, alkaline earth metals, lithium and rare earth elements to appropriately promote the aromatization reaction in the catalytic cracking reaction of naphtha, gasoline, diesel and other fractions, and co-produce aromatics (the yield of ethylene + propylene + aromatics is 60% to 80%) while producing olefins.

[0006] CN1370216A discloses that C 4+ A method for catalytically producing light olefins from naphtha feedstock was developed. Phosphorus-containing ZSM-5 and ZSM-11 zeolites were prepared using inert matrix materials such as silica and clay. By minimizing side reactions such as hydrogen transfer under a steam environment, olefins containing C4–C66 olefins could be produced. 12Straight-run or cracked naphtha feedstocks of olefins or alkanes are directly converted into more valuable light olefins such as ethylene and propylene, and aromatics such as toluene and xylene.

[0007] CN100509714C uses a silicon-modified catalyst for the catalytic conversion of C4 olefins to produce ethylene, propylene, and aromatics. It can achieve high yields of ethylene and propylene, and the generated aromatics contain a relatively high amount of p-xylene.

[0008] Most of the aforementioned routes for simultaneously producing aromatics and light olefins from light hydrocarbons rely on light hydrocarbon aromatization technology platforms. Benefiting from the relatively milder operating conditions compared to catalytic cracking, light hydrocarbon aromatization offers significant advantages such as lower feedstock requirements, lower coke yield, and less processing loss. However, current research and applications primarily focus on fixed-bed catalysts and the process stage, and problems such as unstable reaction temperatures, low propylene yield, rapid catalyst deactivation due to coking, and the need for frequent regeneration still exist. Summary of the Invention

[0009] The purpose of this invention is to address the problems of existing fixed-bed light hydrocarbon aromatization processes, which generally only produce aromatics, as well as severe catalyst coking and poor catalyst regeneration stability. This invention provides a light hydrocarbon conversion catalyst that produces high propylene yields and its preparation method. This catalyst can achieve high yields of low-carbon olefins and aromatics, especially propylene, while maintaining stable operation. Furthermore, the catalyst exhibits strong resistance to coking, a long single-pass reaction cycle, and excellent regeneration performance suitable for multiple reaction regeneration operations.

[0010] To achieve the above objectives, a first aspect of the present invention provides a light hydrocarbon conversion catalyst for producing propylene, characterized in that the catalyst comprises a composite support and an oxide of a Group VA element supported on the composite support; based on the composite support, the composite support contains 5-40 wt% of hydrogen-form ZSM-48 (HZSM-48) zeolite, 5-30 wt% of hydrogen-form ZSM-5 (HZSM-5) zeolite, 0.5-20 wt% of zirconium oxide and 10-89.5 wt% of alumina.

[0011] To achieve the above objectives, a second aspect of the present invention provides a method for preparing a light hydrocarbon conversion catalyst that produces a high amount of propylene, characterized in that the method comprises: (1) preparing a composite powder containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite and zirconium oxide; (2) preparing a spherical composite support containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite, zirconium oxide and alumina; and (3) loading a Group VA element.

[0012] To achieve the above objectives, a third aspect of the present invention also provides a method for converting light hydrocarbons to produce propylene, the method comprising contacting and reacting light hydrocarbons with a catalyst under light hydrocarbon conversion conditions, characterized in that the catalyst is the catalyst of the present invention described above or the catalyst prepared by the method of the present invention.

[0013] The catalyst provided by this invention can produce low-carbon olefins and aromatics in light hydrocarbon conversion reactions, with a low-carbon olefin yield of more than 40% by mass and an aromatic yield of more than 10% by mass. It can simultaneously achieve high yields of both low-carbon olefins and aromatics, especially with an extremely high propylene yield of more than 25% by mass. At the same time, the catalyst has strong resistance to coking, a long single-pass reaction cycle, and good regeneration performance. Attached Figure Description

[0014] Figure 1 These are TEM images of the relevant zeolites in Example 1, where a is a TEM image of hydrogen-form ZSM-5 zeolite, b is a TEM image of hydrogen-form ZSM-5 zeolite in composite support A1, c is a TEM image of hydrogen-form ZSM-48 zeolite, and d is a TEM image of hydrogen-form ZSM-48 zeolite in composite support A1.

[0015] Figure 2 The diagram shows the pore size distribution of the catalysts (S1-S5 and DS1) prepared in Examples 1-5 and Comparative Example 1. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of the present invention provides a light hydrocarbon conversion catalyst for producing propylene, characterized in that the catalyst comprises a composite support and an oxide of a Group VA element supported on the composite support; based on the composite support, the composite support contains 5-40 wt% of hydrogen-form ZSM-48 zeolite, 5-30 wt% of hydrogen-form ZSM-5 zeolite, 0.5-20 wt% of zirconium oxide and 10-89.5 wt% of alumina.

[0018] The inventors have discovered that the catalyst of this invention, by defining specific components and contents of the composite support and combining them with specific contents of the supported components, can effectively improve the catalytic activity of the catalyst. When the catalyst is used to process light hydrocarbons, especially for the conversion reaction of light naphtha, it can simultaneously achieve high yields of low-carbon olefins and aromatics, especially extremely high yields of propylene. It also improves the catalyst's resistance to coking, extends the single-pass reaction cycle of the catalyst, and has excellent regeneration performance, making it suitable for multiple reaction regeneration operations.

[0019] Based on extensive experimentation, the inventors further discovered that the highly acidic hydrogen-form ZSM-48 and ZSM-5 zeolites in the composite support can activate light naphtha components into carbocations. Their different pore structures also exhibit different reaction functions. For example, the unique single-channel structure of hydrogen-form ZSM-48 zeolite is more conducive to initiating a chain reaction of carbocations and producing large quantities of propylene through β-bond cleavage. The three-dimensional pore structure of hydrogen-form ZSM-5 zeolite facilitates the rapid diffusion of large amounts of ethylene and propylene molecules out of the reaction system while maintaining certain cyclization, dehydrogenation, and aromatization properties for aromatic hydrocarbon production. Furthermore, the zirconium oxide in the composite support forms additional mesoporous structures on the surface of hydrogen-form ZSM-5 zeolite, accelerating the diffusion of reactants and products and further inhibiting bimolecular reactions that consume low-carbon olefins, such as hydrogen transfer, thus further improving the selectivity of low-carbon olefins. The group VA elements supported on the composite support can effectively reduce catalyst coking, extend the single-pass reaction time of the catalyst, and improve the crushing strength of the spherical support, giving it excellent regeneration performance and thus increasing the overall service life of the catalyst.

[0020] Therefore, in the catalyst provided by the present invention, the composite support contains, based on the composite support, 5-40 wt% of hydrogen-form ZSM-48 zeolite, 5-30 wt% of hydrogen-form ZSM-5 zeolite, 0.5-20 wt% of zirconium oxide, and 10-89.5 wt% of alumina. From the perspective of improving the structural compatibility between the main components of the composite support and significantly enhancing catalyst performance, the composite support preferably contains 10-40 wt% of hydrogen-form ZSM-48 zeolite, 10-30 wt% of hydrogen-form ZSM-5 zeolite, 0.5-10 wt% of zirconium oxide, and 20-79.5 wt% of alumina. In the catalyst provided by the present invention, particularly by controlling the zirconium oxide content, it is more beneficial to increase the proportion of mesoporous and microporous structures, thereby increasing the yield of low-carbon olefins, especially propylene. The zirconium oxide content is 0.5-20 wt%, for example, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 10 wt%, 20 wt%, and any value within any range of any two values, preferably 0.5-10 wt%.

[0021] The hydrogen-form ZSM-48 zeolite preferably has a SiO2 / Al2O3 molar ratio of 80-400:1, for example, 80:1, 100:1, 120:1, 150:1, 200:1, 300:1, 400:1, and any value within the range of any two values; more preferably, the SiO2 / Al2O3 molar ratio is 90-220:1.

[0022] The hydrogen-form ZSM-5 zeolite preferably has a SiO2 / Al2O3 molar ratio of 100-300:1, for example, 100:1, 120:1, 150:1, 200:1, 250:1, 300:1, and any value within the range of any two values. More preferably, the SiO2 / Al2O3 molar ratio is 120-200:1.

[0023] The alumina crystal form is selected from at least one of α-Al2O3, β-Al2O3 and γ-Al2O3, preferably γ-Al2O3.

[0024] In the catalyst, based on the composite support, the content of Group VA elements, calculated as oxides, is 1-10 wt%, for example, 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, or any value within any range of two such values, preferably 1.5-9 wt%. This invention, by controlling the content of Group VA elements, is more conducive to improving catalyst lifespan, thereby increasing the yield of aromatics and low-carbon olefins. Preferably, the Group VA elements are selected from phosphorus and / or antimony, with phosphorus being preferred, but the invention is not limited thereto.

[0025] In the catalyst, the composite support is spherical in shape with a particle size of 1.2-2.5 mm, for example, 1.2 mm, 1.4 mm, 1.6 mm, 2.0 mm, 2.5 mm, or any value within the range of any two values, preferably with a particle size of 1.4-2.2 mm;

[0026] The catalyst of this invention has a total specific surface area of ​​280-450 m². 2 / g, preferably 300-440m 2 / g; mesoporous specific surface area is 40-300m² 2 / g, preferably 65-250m 2 / g; mesoporous pore volume is 0.12-1.0cm³ 3 / g, preferably 0.12-0.50cm 3 / g; the most probable pore diameter is 2.8-10nm, preferably 2.9-7nm.

[0027] The present invention also provides a method for preparing a light hydrocarbon conversion catalyst that produces a large amount of propylene, characterized in that the method includes: (1) preparing a composite powder containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite and zirconium oxide; (2) preparing a spherical composite support containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite, zirconium oxide and alumina; and (3) loading a Group VA element.

[0028] In the preparation method of the present invention, step (1) is more specifically described as follows: hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite and an aqueous solution of soluble zirconium compound are mixed, ammonia is added dropwise until the pH of the mixed solution is 8-10, and the resulting flocculent solution is subjected to hydrothermal treatment in a closed hydrothermal synthesis reactor and then filtered, dried and calcined to obtain composite powder.

[0029] The concentration of the soluble zirconium compound in the aqueous solution is 0.5-30 wt%, preferably 1-20 wt%. The hydrothermal treatment is performed at a temperature of 100-300℃ for 2-48 hours. The drying conditions are preferably 30-150℃ for 2-6 hours. The calcination conditions are preferably 500-700℃ for 2-6 hours.

[0030] The weight ratio of the mixed hydrogen-form zeolite of ZSM-48 and ZSM-5 to the soluble zirconium compound solution is 1:0.1-10, preferably 1:0.2-8, wherein the soluble zirconium compound solution is calculated based on soluble zirconium compounds.

[0031] The soluble zirconium compound can be selected from a wide range of types, including but not limited to zirconium oxychloride and zirconium nitrate, with zirconium oxychloride being preferred. In this invention, the ammonia solution precipitates the soluble zirconium compound (zirconium oxychloride) to form zirconium hydroxide. Preferably, the concentration of ammonia in the ammonia solution is 1-25 wt%, more preferably 4-15 wt%.

[0032] In the preparation method of the present invention, step (2) is more specifically described as follows: the slurry obtained by mixing the composite powder and aluminum sol is drop-shaped in an oil-ammonia column, and the collected wet balls are dried and calcined to obtain the spherical composite carrier.

[0033] The alumina content in the alumina sol is 8-16 wt%, preferably 8-12 wt%. The alumina sol is obtained by gelation of an aluminum source with an acid solution. The aluminum source includes, but is not limited to, boehmite or alumina sol, but is preferably boehmite. The acid is nitric acid, hydrochloric acid, formic acid, or acetic acid; the concentration of the acid in the acid solution is 0.1-5 wt%, preferably 0.5-2 wt%. The weight ratio of the aluminum source to pure acid is 1:0.02-0.2, preferably 1:0.04-0.12, wherein the aluminum source is calculated as alumina. The gelation time is 1-12 hours, preferably 2-8 hours.

[0034] The alumina content in the aluminum sol described in this invention is crucial to the droplet formation effect of the aluminum sol. If the content is too low, a spherical carrier cannot be obtained; if the content is too high, it will not flow and complete the droplet formation process. The alumina content in the aluminum sol is 8-16 wt%, preferably 8-12 wt%.

[0035] The weight ratio of the composite powder to the alumina sol is 1:2-10, preferably 1:5-8. The slurry obtained by mixing the composite powder and the alumina sol has a solid content of 18-30 wt%, preferably 20-28 wt%, where the solid content refers to the sum of the contents of hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite, zirconium oxide, and alumina.

[0036] In the process of droplet formation of the slurry in an oil-ammonia column, preferably, the oil phase in the oil-ammonia column is kerosene, wherein the kerosene is preferably C24-44-44-44-44-44-44-44-44-44-44-44-44-44-44-44-44-5 ... 10 -C 16 The slurry contains alkanes; the concentration of the ammonia phase is preferably 5-10 wt%; and the dropping temperature is preferably 10-40℃. For example, the slurry is fed into an oil-ammonia column for dropping and forming, and the wet balls are removed from the ammonia phase and dried, preferably at 50-150℃ for 8-24 hours, to obtain dry balls. The dry balls are then calcined at 500-800℃ for 2-8 hours to obtain a spherical composite carrier. The particle size of the spherical composite carrier is 1.2-2.5 mm, preferably 1.4-2.2 mm.

[0037] In the preparation method of the present invention, step (3) is more specifically described as follows: under the condition that the weight ratio of the spherical composite support to the solution containing the soluble Group VA element compound is 1:0.5-1.2, preferably 1:0.5-1, the spherical composite support is immersed in the solution containing the soluble Group VA element compound, and then dried and calcined to obtain the finished spherical catalyst.

[0038] The spherical composite support and the solution containing soluble Group VA element compounds are preferably impregnated at 10-40°C for 1-8 hours, more preferably for 2-4 hours, and the impregnated product is preferably dried at 90-150°C for 4-20 hours, and the dried product is preferably calcined at 500-700°C for 2-8 hours, more preferably for 4-6 hours, to obtain the catalyst.

[0039] The soluble Group VA element compounds include, but are not limited to, at least one of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, antimony nitrate, and antimony acetate. In this invention, unless otherwise specified, "soluble compound" means a compound that is readily soluble in water, or readily soluble in water with the aid of an auxiliary agent.

[0040] The catalyst regeneration method of the present invention includes: after unloading the catalyst, placing it in a muffle furnace for carbonization regeneration in air, with a regeneration temperature of 400-600℃ and a time of 2-10h, to obtain a regenerated catalyst.

[0041] The present invention further provides a method for converting light hydrocarbons to produce propylene, the method comprising contacting and reacting light hydrocarbons with a catalyst under light hydrocarbon conversion conditions, characterized in that the catalyst is the catalyst of the present invention described above or the catalyst prepared by the method of the present invention.

[0042] The light hydrocarbon conversion method provided by this invention converts light hydrocarbons (especially light naphtha) into low-carbon olefins and aromatics under non-hydrogen-exposed conditions. That is, light naphtha undergoes a series of reactions such as cracking and aromatization under the action of a catalyst to generate propylene-rich liquefied gas components and ethylene-rich dry gas components, while producing some aromatic liquid products as by-products.

[0043] This invention offers a wide range of choices for the light hydrocarbons. Preferably, the light hydrocarbons are a mixture of C4-C8 hydrocarbons, and more preferably, light naphtha containing C5-C7 hydrocarbons. In this invention, the light naphtha is a mixture of low-carbon hydrocarbons (C4-C8); the source of the light naphtha is not limited.

[0044] The light hydrocarbon conversion method described herein includes the following conversion conditions: a temperature of 350-650℃, preferably 400-600℃, more preferably 500-600℃; a pressure of 0.001-2MPa, preferably 0.005-1MPa, more preferably 0.01-0.5MPa; and a mass hourly space velocity (HSV) of 0.01-10h. -1 The preferred mass hourly space velocity is 0.05-5 h⁻¹. -1 More preferably, the mass hourly space velocity is 0.1-2 h. -1 .

[0045] The method for converting light hydrocarbons is characterized in that the method is carried out in the presence of an inert gas. The volume ratio of the inert gas to the light hydrocarbons is 500-2000:1, preferably 600-1800:1, and more preferably 1000-1500:1; the inert gas is N2 or CO2.

[0046] The light hydrocarbon conversion method provided by this invention eliminates the need for pre-refining of light hydrocarbons (especially light naphtha); the reaction can be carried out using a moving bed reactor or a fixed bed reactor, with a moving bed reactor being preferred to ensure a more stable and continuous reaction; to avoid frequent reactor switching due to catalyst regeneration, a moving bed device with multiple reactors is preferred for the reaction.

[0047] The present invention will be further illustrated by the following examples, but these examples do not limit the scope of the invention.

[0048] In the examples, the specific surface area and mesopore volume parameters were both determined using the ASTM D4365 method.

[0049] The testing instrument was the Micromeritics AsAp2400 static nitrogen adsorption instrument.

[0050] Test procedure: The catalyst sample was degassed at 300℃ for 4 hours until a vacuum of 1.33 × 10⁻⁶ was reached. -2 Pa, and then nitrogen gas is brought into contact with the adsorbent at liquid nitrogen temperature (-196℃) to reach static adsorption equilibrium. The amount of nitrogen adsorbed by the adsorbent is calculated from the difference between the nitrogen gas inlet and the amount remaining in the gas phase after adsorption. Then, the specific surface area and pore volume are calculated using the two-parameter BET formula, and the pore size distribution and corresponding mesopore volume are calculated using the BJH formula.

[0051] Particle size parameters were determined using ASTM D4513-11.

[0052] The most probable bore diameter parameters were determined using ASTM D4641-17.

[0053] Example 1

[0054] (1) Preparation of composite powder

[0055] 13g of zirconium oxychloride (ZrOCl2·8H2O, analytical grade) was dissolved in 200g of deionized water to form a clear aqueous solution. Under stirring, 15g of hydrogen-form ZSM-48 zeolite (SiO2 / Al2O3 molar ratio of 100) and 10g of hydrogen-form ZSM-5 zeolite (SiO2 / Al2O3 molar ratio of 150) were added to the solution. After stirring evenly, 8wt% ammonia water was added dropwise until the pH value reached 8. The resulting flocculent aqueous solution was transferred to a stainless steel hydrothermal synthesis reactor with a polytetrafluoroethylene liner and then placed in an oven for hydrothermal treatment at 120℃ for 24h. After cooling, the filtered powder was dried at 110℃ for 4h and calcined at 550℃ for 4h to obtain the composite powder.

[0056] (2) Preparation of spherical composite carriers

[0057] Take 16g of pseudoboehmite ( SB powder (alumina content of 75wt%) was added to 95g of nitric acid aqueous solution with a concentration of 1.1wt% under stirring conditions. After 2 hours of gelation, an aluminum sol with an alumina content of 11wt% was obtained. 18g of the composite powder obtained in (1) was added to it and stirred at high speed at 120rpm for 3h to obtain a slurry containing hydrogen-type ZSM-48 zeolite, hydrogen-type ZSM-5 zeolite, zirconium oxide and alumina. The solid content in the slurry was 23wt%.

[0058] The above slurry was drop-balled in an oil-ammonia column: the drop-ball temperature was 15℃, the oil phase in the oil-ammonia column was kerosene with a thickness of 10cm, the ammonia phase had a thickness of 200cm, and the ammonia concentration was 6wt%. The wet balls were taken out from the bottom of the ammonia layer, dried at 60℃ for 10h, and calcined at 550℃ for 4h to obtain the composite carrier, designated A1.

[0059] TEM image of hydrogen-form ZSM-5 zeolite in composite support A1 is shown below. Figure 1 (b) shows the TEM image of hydrogen-form ZSM-48 zeolite in composite support A1. Figure 1 As shown in (d). Figure 1 It can be seen that, compared to Figure 1 (a) TEM image of hydrogen-form ZSM-5 zeolite and Figure 1 (c) TEM image of hydrogen-form ZSM-48 zeolite. The zirconium oxide in the composite support forms a rich mesoporous structure on the surface of the hydrogen-form zeolite, which accelerates the diffusion of reactants and products, further inhibits the bimolecular reactions that consume low-carbon olefins, such as hydrogen transfer, and improves the selectivity of low-carbon olefins, thus significantly enhancing the reaction effect.

[0060] (3) Loading elements of the VA family

[0061] 15g of composite support A1 was impregnated with 10g of a solution containing 6wt% phosphoric acid at 20℃ for 2h. The impregnated solid was dried at 110℃ for 4h and calcined at 550℃ for 4h to obtain the catalyst, which was designated as S1.

[0062] The pore distribution curve of catalyst S1 is shown in the figure below. Figure 2 ,Depend on Figure 2 It can be seen that after the introduction of zirconium oxide, catalyst S1 has a distinct mesoporous structure.

[0063] The compositions of composite support A1 and catalyst S1 are listed in Table 1, and their physical properties are listed in Table 2.

[0064] Example 2

[0065] Same as Example 1, except that in step (1), the hydrogen form ZSM-48 zeolite and hydrogen form ZSM-5 zeolite are replaced with 10g and 15g respectively.

[0066] The resulting composite carrier is designated A2.

[0067] The obtained catalyst is designated S2. The pore distribution curve of catalyst S2 is shown below. Figure 2 ,Depend on Figure 2 It can be seen that the zeolite ratio of catalyst S2 is slightly different from that of catalyst S1, but due to the introduction of the same amount of zirconium oxide, it still exhibits a clear mesoporous structure.

[0068] The compositions of composite support A2 and catalyst S2 are listed in Table 1, and their physical properties are listed in Table 2.

[0069] Example 3

[0070] Same as Example 1, except that in step (1), the hydrogen form ZSM-48 zeolite and hydrogen form ZSM-5 zeolite are replaced with 20g and 10g respectively.

[0071] The resulting composite carrier is designated A3.

[0072] The obtained catalyst is designated S3. The pore distribution curve of catalyst S3 is shown below. Figure 2 ,Depend on Figure 2 It can be seen that the zeolite ratio of catalyst S3 is slightly different from that of catalyst S1, but due to the introduction of the same amount of zirconium oxide, it still exhibits a clear mesoporous structure.

[0073] The compositions of composite support A3 and catalyst S3 are listed in Table 1, and their physical properties are listed in Table 2.

[0074] Example 4

[0075] Same as Example 1, except that the amount of zirconium oxychloride added in step (1) is changed to 2.6g and the amount of composite powder in step (2) is 13g.

[0076] The resulting composite carrier is designated A4.

[0077] The obtained catalyst is designated S4. The pore distribution curve of catalyst S4 is shown below. Figure 2 ,Depend on Figure 2 It can be seen that, compared with catalyst S1, catalyst S4 has a reduced mesoporous specific surface area and pore volume due to the reduced zirconium oxide content.

[0078] The compositions of composite support A4 and catalyst S4 are listed in Table 1, and their physical properties are listed in Table 2.

[0079] Example 5

[0080] Same as Example 1, except that zirconium oxychloride in step (1) is replaced with 23.5g and the composite powder in step (2) is 25.5g.

[0081] The resulting composite carrier is designated A5.

[0082] The obtained catalyst is designated S5. The pore distribution curve of catalyst S5 is shown below. Figure 2 ,Depend on Figure 2 It can be seen that, compared with catalyst S1, catalyst S5 has an increased mesoporous specific surface area and pore volume due to the increased zirconium oxide content.

[0083] The compositions of composite support A5 and catalyst S5 are listed in Table 1, and their physical properties are listed in Table 2.

[0084] Example 6

[0085] Same as Example 1, except that in step (3), the phosphoric acid solution is replaced with a 10g solution of 12wt% phosphoric acid.

[0086] The obtained catalyst is designated S6.

[0087] The compositions of composite support A1 and catalyst S6 are listed in Table 1, and their physical properties are listed in Table 2.

[0088] Example 7

[0089] Same as Example 1, except that in step (3), the phosphoric acid solution is replaced with 10g of a solution containing 6wt% antimony nitrate.

[0090] The obtained catalyst is designated S7.

[0091] The compositions of composite support A1 and catalyst S7 are listed in Table 1, and their physical properties are listed in Table 2.

[0092] Example 8

[0093] Same as Example 1, except that in step (1), the SiO2 / Al2O3 of the hydrogen-type ZSM-48 zeolite is changed to 200.

[0094] The resulting composite carrier is designated A8.

[0095] The obtained catalyst is designated S8.

[0096] The compositions of composite support A8 and catalyst S8 are listed in Table 1, and their physical properties are listed in Table 2.

[0097] Comparative Example 1

[0098] This comparative example illustrates a comparative catalyst and its preparation with a composite support containing ZSM-48 zeolite, ZSM-5 zeolite, and alumina, but without zirconium oxide.

[0099] Take 16g of pseudoboehmite ( SB powder (alumina content of 75 wt%) was mixed with 95 g of 1.1 wt% nitric acid aqueous solution under stirring conditions. After 2 hours of gelation, an alumina sol with an alumina content of 11 wt% was obtained. 9 g of hydrogen-form ZSM-48 zeolite (SiO2 / Al2O3 molar ratio of 200) and 9 g of hydrogen-form ZSM-5 zeolite (SiO2 / Al2O3 molar ratio of 150) were added to the sol and stirred at high speed at 120 rpm for 3 hours to obtain a slurry containing zeolite and a solid content of 23 wt%.

[0100] The above slurry was drop-balled in an oil-ammonia column at a dropping temperature of 15°C. The oil phase in the oil-ammonia column was kerosene with a thickness of 10 cm, and the ammonia phase had a thickness of 200 cm and an ammonia concentration of 6 wt%. The wet balls were removed from the bottom of the ammonia layer, dried at 60°C for 10 h, and calcined at 550°C for 4 h to obtain the comparative composite support DA1. The group VA element was then loaded using the method in step 1(3) of Example 1 to obtain the comparative catalyst, designated DS1.

[0101] The pore distribution curve of catalyst DS1 is shown in the figure. Figure 2 ,Depend on Figure 2 It can be seen that the catalyst DS1, which does not contain zirconium oxide on the composite support, does not have a mesoporous structure and is mainly composed of micropores.

[0102] The composition of catalyst DS1 is listed in Table 1, and its physical properties are listed in Table 2.

[0103] Comparative Example 2

[0104] This comparative example illustrates a comparative catalyst with a composite support containing zirconium oxide and alumina but without zeolite, and its preparation process.

[0105] (1) Preparation of zirconia powder

[0106] 37.5g of zirconium oxychloride was dissolved in 100g of deionized water to form a clear aqueous solution. Ammonia was added dropwise until the pH value reached 8.0. The solution was filtered, and the resulting solid was washed with water, dried at 110℃ for 4h, and calcined at 550℃ for 4h to obtain zirconium oxide powder.

[0107] (2) Preparation of composite carrier

[0108] Take 16g of pseudoboehmite ( SB powder (alumina content of 75wt%) was added to a nitric acid aqueous solution with a concentration of 1.1wt% under stirring conditions. After 2 hours of gelation, an aluminum sol with an alumina content of 11wt% was obtained. 18g of zirconium oxide powder prepared in (1) was added to the sol and stirred at a high speed of 120rpm for 3 hours to obtain a slurry containing zirconium oxide with a solid content of 23wt%.

[0109] The above slurry was drop-balled in an oil-ammonia column at a dropping temperature of 15°C. The oil phase of the oil-ammonia column was kerosene with a thickness of 10 cm, and the ammonia phase had a thickness of 200 cm and an ammonia concentration of 6 wt%. The wet balls were removed from the bottom of the ammonia layer, dried at 60°C for 10 h, and calcined at 550°C for 4 h to obtain the comparative composite support DA2. The comparative catalyst, numbered DS2, was obtained by loading a group VA element using the method in step 1(3).

[0110] The composition of the catalyst DS2 is listed in Table 1, and its physical properties are listed in Table 2.

[0111] Comparative Example 3

[0112] This comparative example illustrates a comparative catalyst and its preparation process with a composite support containing ZSM-5 zeolite, zirconium oxide, and alumina, but without ZSM-48 zeolite.

[0113] The preparation of the composite carrier is the same as in Example 1, except that in step (1), 25g of hydrogen-form ZSM-5 zeolite (SiO2 / Al2O3 molar ratio of 150) is added to the aluminum sol instead of hydrogen-form ZSM-48 zeolite.

[0114] The composite support DA3 was obtained, and then the group VA element was loaded using the method in step 1(3) of Example 1 to obtain the comparative catalyst, which was numbered DS3.

[0115] The composition of the catalyst DS3 is listed in Table 1, and its physical properties are listed in Table 2.

[0116] Comparative Example 4

[0117] This comparative example illustrates a comparative catalyst and its preparation process for a composite support containing ZSM-48 zeolite, zirconium oxide, and alumina, but without ZSM-5 zeolite.

[0118] The preparation of the composite carrier is the same as in Example 1, except that in step (1), 25g of hydrogen-form ZSM-48 zeolite (SiO2 / Al2O3 molar ratio of 100) is added to the aluminum sol instead of hydrogen-form ZSM-5 zeolite.

[0119] The composite support DA4 was obtained, and then the group VA element was loaded using the method in step 1(3) to obtain the comparative catalyst, which was numbered DS4.

[0120] The composition of catalyst DS4 is listed in Table 1, and its physical properties are listed in Table 2.

[0121] Table 1

[0122]

[0123] Note: *Content based on composite carrier, expressed as oxides.

[0124] Table 2

[0125]

[0126]

[0127] As can be seen from the data in Table 2, the mesoporous specific surface area of ​​catalysts S1-S8 prepared in Examples 1-8 of the present invention is higher than that of comparative catalysts DS1-DS4, and the catalysts of the present invention all have additional mesoporous structures.

[0128] Examples 9-16

[0129] Examples 9-16 illustrate the light hydrocarbon conversion method provided by the present invention.

[0130] The composition of the raw material is shown in Table 3.

[0131] The catalysts S1-S8 prepared in Examples 1-8 were respectively packed into small fixed-bed reactors.

[0132] The reaction conditions included: a temperature of 590℃, a pressure of 0.1 MPa, and a mass hourly space velocity (H₂Sv) of 0.5 h⁻¹. -1 The time was 24 hours, and the volume ratio of nitrogen to light naphtha was 1500:1.

[0133] The reaction results are listed in Table 4.

[0134] Comparative Examples 5-8

[0135] Comparative Examples 5-8 illustrate the light hydrocarbon conversion methods using comparative catalysts.

[0136] Same as Example 9, except that the comparative catalysts DS1-DS4 prepared in Comparative Examples 1-4 were used instead of catalyst S1. The reaction results are listed in Table 4.

[0137] Table 3

[0138]

[0139] Table 4

[0140]

[0141] In Table 4, the dry gases are H2, CH4 and C2 hydrocarbons.

[0142] As shown in Table 4, the catalyst provided by this invention is used for the conversion of light hydrocarbons, with a low-carbon olefin yield of more than 40% by mass and an aromatic hydrocarbon yield of more than 10% by mass. It can simultaneously obtain high low-carbon olefin and aromatic hydrocarbon yields, especially with an extremely high propylene yield of more than 25% by mass. The low-carbon olefin and propylene yields of this invention are both superior to those of the comparative example.

[0143] Example 17

[0144] This embodiment illustrates the stability of the catalyst of the present invention.

[0145] The catalyst S1 prepared in Example 1 was packed into a small fixed-bed reactor. Light naphtha with the composition shown in Table 3 was introduced into the reactor as feedstock, contacting and reacting with the catalyst S1. The reaction conditions included: a temperature of 590°C, a pressure of 0.1 MPa, and a mass hourly space velocity of 0.5 h⁻¹. -1 The volume ratio of nitrogen to naphtha was 1500, and the reaction results are listed in Table 5.

[0146] Table 5

[0147] Continuous reaction time, h 24 48 72 96 120 Dry gas yield, wt% 37.5 37.1 36.0 35.1 34.2 <![CDATA[(C3 + C4) yield, wt%]]> 46.8 46.7 47.5 47.8 48.0 <![CDATA[C 5+ Yield, wt% 15.7 16.2 16.5 17.1 17.8 Ethylene yield, wt% 17.2 17.0 16.9 16.6 16.1 Propylene yield, wt% 29.4 29.7 29.3 29.0 28.6 Low carbon olefin yield, wt% 46.6 46.7 46.2 45.6 44.7 Aromatics yield, wt% 12.7 12.1 11.7 11.2 10.9

[0148] As shown in Table 5, with the extension of reaction time, the yield of low-carbon olefins decreased from 46.6 wt% after 24 h of continuous reaction to 44.7 wt% after 120 h of continuous reaction, with an average low-carbon olefin yield greater than 45.9 wt%. Specifically, the propylene yield decreased from 29.4 wt% after 24 h of continuous reaction to 28.6 wt% after 120 h of continuous reaction, with an average propylene yield greater than 29.2 wt%. The aromatics yield decreased from 12.7 wt% after 24 h of continuous reaction to 10.9 wt% after 120 h of continuous reaction, with an average aromatics yield greater than 11.7 wt%. It is evident that the catalyst of this invention exhibits strong resistance to coking in light hydrocarbon conversion reactions, a long single-pass reaction cycle, and good reactivity, selectivity for low-carbon olefins and aromatics, and reaction stability, especially with extremely high propylene selectivity.

[0149] Example 18

[0150] This embodiment illustrates the regeneration of the catalyst of the present invention.

[0151] The catalyst S1 prepared in Example 1 was packed into a small fixed-bed reactor. Light naphtha with the composition shown in Table 3 was introduced into the reactor as feedstock, contacting and reacting with the catalyst S1. The reaction conditions included: a temperature of 590°C, a pressure of 0.1 MPa, and a mass hourly space velocity of 0.5 h⁻¹. -1 The volume ratio of nitrogen to light naphtha is 1500, and catalyst S1, which has been reacting continuously for 120 hours, is used as a deactivated catalyst for regeneration.

[0152] Regeneration method: After unloading the catalyst, it was placed in a muffle furnace for carbonization in air for regeneration. The regeneration conditions included a temperature of 500℃ and a time of 8 hours. The regenerated catalyst was then reused in the reaction for another 120 hours. The reaction results are listed in Table 6.

[0153] Table 6

[0154] Catalyst regeneration times 0 1 Dry gas yield, wt% 34.2 34.0 <![CDATA[(C3 + C4) yield, wt%]]> 48.0 47.9 <![CDATA[C 5+ Yield, wt% 17.8 18.1 Ethylene yield, wt% 16.1 15.8 Propylene yield, wt% 28.6 28.3 Low carbon olefin yield, wt% 44.7 44.1 Aromatics yield, wt% 10.9 10.8

[0155] As can be seen from Table 6, the catalytic activity of catalyst S1 provided in Example 1 after regeneration is very close to that before regeneration, indicating that the catalyst provided by the present invention has good regeneration performance.

[0156] Example 19

[0157] Same as Example 17, except that: the temperature is 520°C, the pressure is 0.5 MPa, and the mass hourly space velocity is 1.0 h⁻¹. -1 The volume ratio of nitrogen to naphtha was 1800:1. The reaction results are shown in Table 7.

[0158] Example 20

[0159] Same as Example 17, except that: the temperature is 560°C, the pressure is 0.3 MPa, and the mass hourly space velocity is 1.5 h⁻¹. -1 The volume ratio of nitrogen to naphtha was 1200:1. The reaction results are shown in Table 7.

[0160] Table 7

[0161]

Claims

1. A light hydrocarbon conversion catalyst that produces a high percentage of propylene, characterized in that, The catalyst comprises a composite support and a Group VA element oxide supported on the composite support; the composite support contains 5-40 wt% hydrogen-form ZSM-48 zeolite, 5-30 wt% hydrogen-form ZSM-5 zeolite, 0.5-20 wt% zirconium oxide, and 10-89.5 wt% alumina, and the catalyst has a mesoporous specific surface area of ​​40-300 m². 2 / g, mesoporous pore volume is 0.12-1.0 cm³ 3 / g.

2. The catalyst according to claim 1, wherein, The composite carrier contains 10-40 wt% hydrogen-form ZSM-48 zeolite, 10-30 wt% hydrogen-form ZSM-5 zeolite, 0.5-10 wt% zirconium oxide, and 20-79.5 wt% alumina.

3. The catalyst according to claim 1, wherein, In the hydrogen-form ZSM-48 zeolite, the SiO2 / Al2O3 molar ratio is 80-400:

1.

4. The catalyst according to claim 1, wherein, In the hydrogen-form ZSM-48 zeolite, the SiO2 / Al2O3 molar ratio is 90-220:

1.

5. The catalyst according to claim 1, wherein, In the hydrogen-form ZSM-5 zeolite, the SiO2 / Al2O3 molar ratio is 100-300:

1.

6. The catalyst according to claim 1, wherein, In the hydrogen-form ZSM-5 zeolite, the SiO2 / Al2O3 molar ratio is 120-200:

1.

7. The catalyst according to claim 1, wherein, The alumina crystal form is selected from at least one of α-Al2O3, β-Al2O3 and γ-Al2O3.

8. The catalyst according to claim 1, wherein, The alumina described is in the crystalline form of γ-Al2O3.

9. The catalyst according to claim 1, wherein, Based on the composite carrier, the content of Group VA elements, calculated as oxides, is 1-10 wt%.

10. The catalyst according to claim 1, wherein, Based on the composite carrier, the content of Group VA elements, calculated as oxides, is 1.5-9 wt%.

11. The catalyst according to claim 1, wherein, The particle size of the composite carrier is 1.2-2.5 mm.

12. The catalyst according to claim 1, wherein, The particle size of the composite carrier is 1.4-2.2 mm.

13. The catalyst according to claim 1, wherein, The Group VA elements mentioned are selected from phosphorus and / or antimony.

14. The catalyst according to claim 1, wherein the total specific surface area is 280-450 m². 2 / g; mesoporous specific surface area is 65-250m² 2 / g; mesoporous pore volume is 0.12-0.50 cm³. 3 / g; the most probable pore diameter is 2.8-10 nm.

15. The catalyst according to claim 14, wherein the total specific surface area is 300-440 m². 2 / g; the most probable pore diameter is 2.9-7nm.

16. A method for preparing a light hydrocarbon conversion catalyst with high propylene yield according to any one of claims 1-15, characterized in that, The method includes: (1) preparing a composite powder containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite and zirconium oxide; (2) preparing a spherical composite support containing hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite, zirconium oxide and alumina; and (3) loading a Group VA element.

17. The preparation method according to claim 16, wherein, The (1) is: a mixture of hydrogen-form ZSM-48 zeolite, hydrogen-form ZSM-5 zeolite and an aqueous solution of a soluble zirconium compound, ammonia water is added dropwise until the pH of the mixed solution is 8-10, and the resulting flocculent solution is subjected to hydrothermal treatment in a closed hydrothermal synthesis kettle and then filtered, dried and calcined to obtain composite powder. The soluble zirconium compound is zirconium oxychloride or zirconium nitrate.

18. The preparation method according to claim 17, wherein the soluble zirconium compound is zirconium oxychloride.

19. The preparation method according to claim 17, wherein, The concentration of the soluble zirconium compound in the aqueous solution is 0.5-30 wt%; the hydrothermal treatment is performed at a temperature of 100-300℃ for 2-48 hours.

20. The preparation method according to claim 19, wherein the concentration of the soluble zirconium compound is 1-20 wt%.

21. The preparation method according to claim 16, wherein, The (2) step is as follows: the slurry obtained by mixing the composite powder and aluminum sol is drop-shaped into balls in an oil-ammonia column, and the collected wet balls are dried and calcined to obtain the spherical composite carrier.

22. The preparation method according to claim 21, wherein, The alumina content in the alumina sol is 8-16 wt%.

23. The preparation method according to claim 21, wherein, The alumina content in the alumina sol is 8-12 wt%.

24. The preparation method according to claim 21, wherein, The aluminum sol is obtained by gelation of an aluminum source and an acid solution; the weight ratio of the aluminum source to pure acid is 1:0.02-0.2, wherein the aluminum source is calculated as alumina; the acid is nitric acid, hydrochloric acid, formic acid or acetic acid; the concentration of the acid in the acid solution is 0.1-5wt%; and the gelation time is 1-12h.

25. The preparation method according to claim 21, wherein, The aluminum sol is obtained by gelation of an aluminum source and an acid solution; the weight ratio of the aluminum source to pure acid is 1:0.04-0.12, wherein the aluminum source is calculated as alumina; the acid is nitric acid, hydrochloric acid, formic acid or acetic acid; the concentration of the acid in the acid solution is 0.5-2wt%; and the gelation time is 2-8h.

26. The preparation method according to claim 21, wherein, The weight ratio of the composite powder to the aluminum sol is 1:2-10.

27. The preparation method according to claim 21, wherein, The weight ratio of the composite powder to the aluminum sol is 1:5-8.

28. The preparation method according to claim 16, wherein, In step (3), the spherical composite carrier is immersed in a solution containing a soluble Group VA element compound, and then dried and calcined; the weight ratio of the spherical composite carrier to the solution containing the soluble Group VA element compound is 1:0.5-1.

2.

29. The preparation method according to claim 28, wherein, The weight ratio of the spherical composite carrier to the solution containing a soluble Group VA element compound is 1:0.5-1.

30. The preparation method according to claim 28, wherein, The concentration of the soluble Group VA element compound in the solution is 1-10 wt%.

31. The preparation method according to claim 28, wherein, The concentration of the soluble Group VA element compound in the solution is 2-8 wt%.

32. The preparation method according to claim 28, wherein, The soluble Group VA element compound is selected from at least one of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, antimony nitrate, and antimony acetate.

33. The catalyst obtained by the preparation method according to any one of claims 16-32.

34. A method for converting light hydrocarbons to produce propylene, the method comprising contacting and reacting light hydrocarbons with a catalyst under light hydrocarbon conversion conditions, characterized in that, The catalyst is any one of claims 1-15 and 33.

35. The light hydrocarbon conversion method according to claim 34, wherein, The light hydrocarbons mentioned are a mixture of C4-C8 hydrocarbons.

36. The light hydrocarbon conversion method according to claim 34, wherein, The light hydrocarbon is a light naphtha containing C5-C7.

37. The light hydrocarbon conversion method according to claim 34, wherein the light hydrocarbon conversion conditions include: Temperature: 350-650℃; Pressure: 0.001-2MPa; Mass hourly space velocity is 0.01-10 h⁻¹ -1 .

38. The light hydrocarbon conversion method according to claim 34, wherein the light hydrocarbon conversion conditions include: Temperature 400-600℃; Pressure 0.005-1MPa; Mass hourly space velocity is 0.05-5 h. -1 .

39. The light hydrocarbon conversion method according to claim 34, wherein the light hydrocarbon conversion conditions include: Temperature: 500-600℃; Pressure: 0.01-0.5MPa; Mass hourly space velocity is 0.1-2 h. -1 .

40. The light hydrocarbon conversion method according to claim 34, characterized in that, This method is carried out in the presence of an inert gas.

41. The light hydrocarbon conversion method according to claim 40, wherein, The volume ratio of the inert gas to the light hydrocarbon is 500-2000:1; the inert gas is N2 or CO2.

42. The light hydrocarbon conversion method according to claim 40, wherein, The volume ratio of the inert gas to the light hydrocarbon is 600-1800:1; the inert gas is N2 or CO2.

43. The light hydrocarbon conversion method according to claim 40, wherein, The volume ratio of the inert gas to the light hydrocarbon is 1000-1500:1; the inert gas is N2 or CO2.

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