Aromatization catalyst, process for its preparation and use

Abstract

The present application relates to the field of catalyst, specifically relates to a kind of aromatization catalyst and its preparation method and application, the catalyst contains the following with weight fraction: a) 0.5-15 parts metal oxide;B) 85-99.5 parts molecular sieve;Wherein, the metal oxide includes the oxide of metal component 1 and the oxide of metal component 2, the molar ratio of metal component 1 and metal component 2 is 0.25-8.0, metal component 1 is one or more of IIB, VIB group and IIIA group metal element;Metal component 2 is IIA group element.The catalyst of the present application is used for aromatization reaction, has the advantages such as aromatization element stability, can be continuously long period stable operation etc..

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to an aromatization catalyst, its preparation method, and its application. Background Technology

[0002] Aromatics, especially light aromatics (BTX, benzene, toluene, xylene), are important basic organic chemical raw materials, with their production volume and scale second only to ethylene and propylene. Currently, my country's annual consumption of aromatics is enormous. Aromatics production mainly comes from catalytic reforming and cracked gasoline extraction processes along the petroleum route, with a small amount coming from coal tar conversion.

[0003] Converting abundant and inexpensive low-carbon hydrocarbon components from petrochemicals and oxygen-containing compounds produced by coal / natural gas chemical processes into high-value-added benzene, toluene, and xylene has become a significant research focus in recent decades. This process route is crucial for alleviating aromatic resource shortages and extending the natural gas / coal chemical industry chain. On the other hand, in recent years, under the major trend of oil product upgrading in my country, there is a need to significantly reduce the olefin content in refined oil products. Catalytic cracking gasoline accounts for as much as 75% of my country's gasoline pool, but a significant characteristic of catalytic cracking gasoline is its high olefin content. Therefore, converting the olefins in catalytic cracking gasoline into aromatics through aromatization is currently an important method for reducing olefin content.

[0004] Developing high-performance catalysts remains one of the most significant factors hindering the advancement of aromatization technology. Recently, researchers have discovered that bifunctional molecular sieves, primarily composed of metal oxides and molecular sieves, are excellent catalysts for the preparation of aromatics from oxygen-containing compounds. Catalysts commonly used for the aromatization of low-carbon hydrocarbons are generally metal-supported catalysts (such as Pt / Al₂O₃, Cr₂O₃ / Al₂O₃, etc.) and molecular sieve catalysts (such as MFI-type, MCM-based, L-type molecular sieves, etc.). Currently, the most studied molecular sieve catalyst is the MFI-type ZSM-5 molecular sieve.

[0005] CN111151292 discloses an aromatization catalyst, its preparation method, and its application. The aromatization catalyst comprises an inorganic oxide, a modified ZSM-5 molecular sieve, and Ga supported on the molecular sieve channels and / or surface. The modified ZSM-5 molecular sieve has a hierarchical pore structure of micropores, mesopores, and macropores, which can reduce the influence of diffusion resistance in the aromatization reaction, slow down the carbon deposition rate, and significantly improve the catalyst's activity, selectivity, stability, and lifespan. When this catalyst is used to catalyze the aromatization reaction of propane, it exhibits high stability.

[0006] CN108479846 discloses an aromatization catalyst and its preparation method. The preparation method includes the following steps: mixing zeolite molecular sieves with a binder to obtain a catalyst precursor; subjecting the catalyst precursor to ion exchange modification and a first modification treatment sequentially, followed by hydrothermal treatment, and then subjecting it to active metal loading and a second modification treatment to obtain the aromatization catalyst. This aromatization catalyst exhibits good resistance to carbon deposition and high aromatization activity, enabling the aromatization reaction to proceed under relatively mild conditions, while also demonstrating high aromatic selectivity and liquid yield.

[0007] CN108404972 also discloses an aromatization catalyst, its preparation method, regeneration method, and aromatization method. The preparation method involves mixing molecular sieve precursors, followed by crystallization, calcination, and acid exchange to obtain a catalyst support. The catalyst support is then subjected to ion exchange modification and a first modification treatment, followed by hydrothermal treatment, and finally active metal loading and a second modification treatment to obtain the aromatization catalyst. This aromatization catalyst was found to have good resistance to carbon deposition and high aromatization activity, enabling the aromatization reaction to proceed under relatively mild conditions, while also exhibiting high olefin conversion and very high liquid yield.

[0008] The literature reports above on aromatization catalysts and their preparation methods mostly focus on improving aromatization activity, with less mention of how to stabilize the aromatizing elements to achieve long-term continuous operation of the catalyst. Long-term stability is a prominent issue currently facing aromatization catalysts. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems of existing aromatization catalysts, such as the difficulty in long-term continuous operation, and to provide a novel aromatization catalyst, its preparation method, and its application. This catalyst, when used in aromatization reactions, has advantages such as stable aromatizing elements and the ability to operate stably for extended periods.

[0010] To achieve the above objectives, a first aspect of the present invention provides an aromatization catalyst, which, by weight fraction, contains:

[0011] a) 0.5-15 parts metal oxides; b) 85-99.5 parts molecular sieves;

[0012] The metal oxide comprises an oxide of metal component 1 and an oxide of metal component 2, wherein the molar ratio of metal component 1 to metal component 2 is (0.25-8.0):1, metal component 1 is one or more metal elements from groups IIB, VIB and IIIA, and metal component 2 is a group IIA element.

[0013] The catalyst of this invention is stable at high temperatures, enabling long-term continuous operation.

[0014] When the catalyst of this invention is used in aromatization reactions, it has the characteristics of stable aromatization elements and can operate stably for a long period of time.

[0015] A second aspect of the present invention provides a method for preparing the catalyst described herein, the method comprising:

[0016] a) Molecular sieve, metal component 1 source, metal component 2 source, and water are used to form precursor A. The molar ratio of each substance in precursor A is molecular sieve: metal component source: water = 1:(0.01-0.25):(0.30-4.0). Except for water, the other components are calculated on a dry basis.

[0017] b) Precursor A is subjected to sealed aging treatment and then dried to form precursor B;

[0018] c) Calcining precursor B.

[0019] The catalyst of this invention is prepared by controlling the ratio of two elements to ensure uniform combination, thereby forming a stable homogeneous complex.

[0020] The catalyst of this invention employs a closed aging process during preparation, which can enhance the bonding force between the metal oxide and the molecular sieve.

[0021] A third aspect of the present invention provides the application of the catalyst in one or more of the following: aromatization of olefins into aromatics, aromatization of methanol into aromatics, and aromatization of alkanes into aromatics.

[0022] The catalyst of this invention is used in the catalytic synthesis of aromatics from C4 olefins at a reaction temperature of 450°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under these conditions, when the catalyst is reacted with C4 olefins, the single-pass operation cycle of the catalyst can reach 200 hours (based on a conversion rate greater than 85% of the initial conversion rate). Compared with the catalyst prepared by impregnating molecular sieves with a single zinc oxide precursor, the single-pass operation cycle of the catalyst is only 150 hours (based on a conversion rate greater than 85% of the initial conversion rate). The single-pass operation cycle of the catalyst is improved by 33.3%, achieving better technical results. Detailed Implementation

[0023] 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.

[0024] This invention provides an aromatization catalyst, which, by weight fraction, contains:

[0025] a) 0.5-15 parts metal oxides; b) 85-99.5 parts molecular sieves;

[0026] The metal oxide comprises an oxide of metal component 1 and an oxide of metal component 2, wherein the molar ratio of metal component 1 to metal component 2 is (0.25-8.0):1, metal component 1 is one or more metal elements from groups IIB, VIB and IIIA, and metal component 2 is a group IIA element.

[0027] According to a particularly preferred embodiment of the present invention, the catalyst wherein the metal component 1 is an aromatization active element, an active element for catalytically converting light hydrocarbons or oxygen-containing compounds into aromatic hydrocarbons. It is selected from one or more combinations of zinc, gallium, molybdenum, and chromium.

[0028] According to a particularly preferred embodiment of the present invention, the metal component 2 is selected from magnesium and / or calcium.

[0029] According to a particularly preferred embodiment of the present invention, the molar ratio of metal component 1 to metal component 2 is (0.45-7.5):1. By adopting the aforementioned preferred embodiment, metal component 1 and metal component 2 can be maintained within a suitable ratio range, thereby stabilizing the aromatizing element and achieving long-term continuous operation of the catalyst.

[0030] According to a particularly preferred embodiment of the present invention, the catalyst contains oxides of metal component 1 and metal component 2 in the form of a homogeneous composite, forming a homogeneous composite oxide, and there are no isolated oxide particles of metal component 1 or metal component 2 with a size of 1 nanometer or larger. By adopting the aforementioned preferred embodiment, a homogeneous composite oxide can be formed between the oxides of metal component 1 and metal component 2. This homogeneous composite oxide has high stability and can achieve long-term continuous operation of the catalyst.

[0031] According to a particularly preferred embodiment of the present invention, the catalyst, wherein the molecular sieve contains at least one of ten-membered rings and twelve-membered ring channels.

[0032] According to a particularly preferred embodiment of the present invention, the catalyst wherein the molecular sieve component is selected from any one or a mixture of two or more of ZSM-5, ZSM-22, EU-1, MCM-22 and ZSM-11 silica-alumina molecular sieves containing ten-membered ring channels. By adopting the aforementioned preferred embodiment, the diffusion advantage of the ten-membered ring can be utilized to improve the selectivity of aromatization products and achieve long-term continuous operation of the catalyst.

[0033] According to a particularly preferred embodiment of the present invention, the aluminum content in the molecular sieve is 0.25-4.5%.

[0034] According to a particularly preferred embodiment of the present invention, the aluminum content in the molecular sieve is 0.55-4.0%.

[0035] According to a particularly preferred embodiment of the present invention, the aluminum content in the molecular sieve is 0.75-4.0%.

[0036] By adopting the aforementioned preferred embodiments, a reasonable number of acidic sites in the molecular sieve can be maintained, and long-term continuous operation of the catalyst can be achieved while maintaining high selectivity for aromatization products.

[0037] According to a particularly preferred embodiment of the present invention, the catalyst has a total specific surface area of ​​40-450 m² / g and a total volume of pores with a diameter of less than 50 nm of 0.05-0.85 m³ / g, as determined by nitrogen adsorption isotherm measurement.

[0038] According to a particularly preferred embodiment of the present invention, the catalyst has a total specific surface area of ​​70-420 m² / g and a total volume of pores with a diameter of less than 50 nm of 0.06-0.80 m³ / g, as measured by nitrogen adsorption isotherm measurement.

[0039] According to a particularly preferred embodiment of the present invention, the catalyst has a total specific surface area of ​​90-400 m² / g and a total volume of pores with a diameter of less than 50 nm of 0.07-0.75 m³ / g, as measured by nitrogen adsorption isotherm measurement.

[0040] By adopting the aforementioned preferred embodiments, a higher pore volume can be utilized to increase the carbon-holding capacity and achieve long-term continuous operation of the catalyst.

[0041] When aromatization catalysts operate continuously for extended periods, changes in the properties of the active aromatizing elements can lead to permanent deactivation. Therefore, the catalyst modification process needs to be optimized. This invention enables long-term continuous operation of the catalyst by adding a second metal component.

[0042] Catalysts possessing the aforementioned characteristics of this invention can all achieve the objectives of this invention, and there are no special requirements for their preparation methods. A second aspect of this invention provides a method for preparing the catalyst described in this invention, the method comprising:

[0043] a) Molecular sieve, metal component 1 source, metal component 2 source, and water are used to form precursor A. The molar ratio of each substance in precursor A is molecular sieve: metal component source: water = 1:(0.01-0.25):(0.30-4.0). Except for water, the other components are calculated on a dry basis.

[0044] b) Precursor A is subjected to sealed aging treatment and then dried to form precursor B;

[0045] c) Calcining precursor B.

[0046] According to a preferred embodiment of the present invention, the molar ratio of each substance in the precursor A of the aromatization catalyst is molecular sieve: metal component source: water = 1:(0.02-0.22):(0.30-4.0), and the remaining components in the raw material except for water are calculated on a dry basis.

[0047] According to a particularly preferred embodiment of the present invention, the molar ratio of each substance in the precursor A of the aromatization catalyst is molecular sieve: metal component source: water = 1:(0.03-0.20):(0.30-4.0), and the remaining components in the raw material, except for water, are calculated on a dry basis.

[0048] By adopting the aforementioned preferred embodiments, a reasonable ratio of molecular sieve to metal components can be maintained, the selectivity of aromatization products can be improved, and long-term continuous operation of the catalyst can be achieved.

[0049] In this invention, the conditions for the sealed aging treatment in step b) can be conventional choices in the art. According to a particularly preferred embodiment of this invention, the conditions for the aging treatment in step b) include: a temperature of 15-85°C and a time of 2-45 hours.

[0050] According to a particularly preferred embodiment of the present invention, in step b), the aging treatment conditions include: a temperature of 25-85°C and a time of 2-40 hours.

[0051] According to a particularly preferred embodiment of the present invention, in step b), the aging treatment conditions include: a temperature of 35-85°C and a time of 2-35 hours.

[0052] According to a particularly preferred embodiment of the present invention, in step b), the sealed aging treatment is carried out in the presence of a carbon dioxide atmosphere.

[0053] By adopting the aforementioned preferred scheme, the bonding force between the metal oxide and the molecular sieve can be strengthened.

[0054] In this invention, the drying conditions in step b) can be conventional choices in the art. According to a particularly preferred embodiment of the invention, the drying conditions in step b) include: a temperature of 85-150°C and a time of 2-48 hours.

[0055] According to a particularly preferred embodiment of the present invention, in step b), the drying conditions include a temperature of 90-140°C and a time of 2-45 hours.

[0056] According to a particularly preferred embodiment of the present invention, in step b), the drying conditions include: a temperature of 95-135°C and a time of 2-40 hours.

[0057] By adopting the aforementioned preferred embodiments, a suitable pore structure can be obtained, enabling the catalyst to operate continuously for a long period.

[0058] In this invention, the calcination conditions in step c) can be conventionally chosen in the art. According to a particularly preferred embodiment of the invention, the calcination conditions in step c) include: a temperature of 350-700°C and a time of 2-42 hours. By adopting the aforementioned preferred embodiment, a suitable pore structure can be obtained, enabling long-term continuous operation of the catalyst.

[0059] According to a particularly preferred embodiment of the present invention, in the preparation method, the range of metal component 1 and metal component 2 sources is relatively wide, for example, selected from at least one of nitrates, carbonates, chlorides, sulfates, molybdates, phosphates, acetates, and fatty alcohol esters. By adopting the aforementioned preferred embodiment, a reasonable ratio of molecular sieve to metal components can be maintained, improving the selectivity of aromatization products and enabling long-term continuous operation of the catalyst.

[0060] The catalyst of this invention ensures the uniform bonding of the two metal elements by controlling the uniformity of the bonding process during the preparation of the catalyst, thereby forming a stable homogeneous complex.

[0061] The invention employs a closed-loop aging process, which strengthens the bond between the metal oxide and the molecular sieve.

[0062] A third aspect of the present invention provides the application of the catalyst in one or more of the following: aromatization of olefins into aromatics, aromatization of methanol into aromatics, and aromatization of alkanes into aromatics.

[0063] The catalyst of this invention is used in the catalytic synthesis of aromatics from C4 olefins at a reaction temperature of 450°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹.-1 Under these conditions, when the catalyst is reacted with C4 olefins, the single-pass operation cycle of the catalyst can reach 200 hours (based on a conversion rate greater than 85% of the initial conversion rate). Compared with the catalyst prepared by impregnating molecular sieves with a single zinc oxide precursor, the single-pass operation cycle of the catalyst is only 150 hours (based on a conversion rate greater than 85% of the initial conversion rate). The single-pass operation cycle of the catalyst is improved by 33.3%, achieving better technical results.

[0064] The technical solution of the present invention will be further described below through embodiments, but the scope of protection of the present invention is not limited by the embodiments.

[0065] The evaluation conditions for the catalysts used in all embodiments and comparative examples of this invention conform to the following ranges: reaction temperature 350-700℃, reaction pressure 0.1-0.8MPa, and aromatization feedstock weight hourly space velocity 0.20-2.5h⁻¹. -1 The specific conditions are as described in the embodiments or comparative examples.

[0066] Example 1

[0067] 29.7 g of zinc nitrate hexahydrate and 23.6 g of calcium nitrate tetrahydrate were mixed with 70 g of water to form a solution. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was taken and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.11:2.4. The resulting product was aged in a sealed environment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0068] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst's single-pass operation cycle could reach 275 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 85%. The catalyst composition is listed in Table 1.

[0069] The catalyst obtained in this embodiment was also used in the methanol aromatization process at a reaction temperature of 420°C, a reaction pressure of 0.10 MPa, and a methanol weight hourly space velocity of 0.7 h⁻¹. -1 Under certain conditions, the catalyst is reacted with methanol, and the single-pass operation cycle of the catalyst can reach 114 hours (based on a conversion rate greater than 85% of the initial conversion rate).

[0070] The catalyst obtained in this example was also used in the propane aromatization process at a reaction temperature of 630°C, a reaction pressure of 0.20 MPa, and a propane weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst is reacted with propane, and the single-pass operation cycle of the catalyst can reach 379 hours (based on a conversion rate greater than 85% of the initial conversion rate).

[0071] Example 2

[0072] 9.1 g of gallium nitrate and 9.9 g of magnesium nitrate were mixed with 12 g of water to form a mixture. 110 g of ZSM-22 molecular sieve with an aluminum content of 1.6 wt% was taken and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.05:0.4. The resulting product was aged in a sealed environment at 40 degrees Celsius for 32 hours. The resulting solid was dried at 120 degrees Celsius for 15 hours. The resulting solid composite was calcined at 450 degrees Celsius for 23 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0073] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 262 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatic yield of 90%. The catalyst composition is listed in Table 1.

[0074] Example 3

[0075] 21 g of ammonium molybdate and 4.2 g of calcium nitrate tetrahydrate were added to 110 g of water to prepare a mixture. 110 g of EU-1 molecular sieve with an aluminum content of 0.85 wt% was added and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.07:3.9. The resulting product was aged in a sealed environment at 55 degrees Celsius for 19 hours. The resulting solid was dried at 132 degrees Celsius for 4 hours. The resulting solid composite was calcined at 680 degrees Celsius for 3 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0076] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 298 hours (based on a conversion rate greater than 85% of the initial conversion rate). The aromatic yield was 79%, and the catalyst composition is listed in Table 1.

[0077] Example 4

[0078] Take 20 g of chromium nitrate nonahydrate, 14.9 g of zinc nitrate hexahydrate and 23.6 g of calcium nitrate tetrahydrate and add 70 g of water to make a mixture. Take 110 g of MCM-22 molecular sieve with an aluminum content of 3.8% by weight and stir evenly. The molar ratio of each substance in the precursor is molecular sieve: metal component source: water = 1.0:0.11:2.4. The obtained product is aged in a sealed environment at 80 degrees for 3 hours. The obtained solid is dried at 100 degrees for 30 hours. The obtained solid composite is calcined at 500 degrees for 14 hours under controlled temperature. The composite metal oxide / molecular sieve is the aromatization catalyst.

[0079] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst's single-pass operation cycle could reach 304 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 82%. The catalyst composition is listed in Table 1.

[0080] Example 5

[0081] Following the steps in Example 1, the precursor was changed to barium nitrate. 21.7 g of zinc nitrate hexahydrate and 23.4 g of barium nitrate were mixed with 70 g of water to form a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was taken and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.11:2.4. The resulting product was aged in a sealed environment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0082] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 237 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatic yield of 72%. The catalyst composition is listed in Table 1.

[0083] Example 6

[0084] Following the steps in Example 1, the contents of zinc nitrate and calcium nitrate were varied. 8.69 g of zinc nitrate hexahydrate and 23.6 g of calcium nitrate tetrahydrate were added to 70 g of water to prepare a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was taken and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.07:2.4, where the molar ratio of metal component 1 and metal component 2 was 0.29. The resulting product was aged in a sealed environment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0085] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle reached 221 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatic yield of 49%. The catalyst composition is listed in Table 1.

[0086] Example 7

[0087] Following the method described in Example 1, an aromatization catalyst was prepared by stepwise impregnation of metal component 1 and metal component 2. First, 29.7 g of zinc nitrate hexahydrate was added to 70 g of water to form a mixture. Then, 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was added and stirred until homogeneous. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.11:2.4. The resulting product was aged in a sealed environment at 80°C for 2.5 hours. The resulting solid was dried at 100°C for 37 hours. The resulting solid composite was calcined at 540°C for 15 hours under controlled temperature. After the above steps were completed, 23.6 g of calcium nitrate tetrahydrate was subjected to the same solution preparation-stirring-sealed aging-drying and controlled temperature calcination steps to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0088] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 206 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatics yield of 70%. The catalyst composition is listed in Table 1.

[0089] Example 8

[0090] Following the method described in Example 1, the aluminum content of the molecular sieve was changed. 29.7 g of zinc nitrate hexahydrate and 23.6 g of calcium nitrate tetrahydrate were added to 70 g of water to prepare a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 0.05% by weight was taken and stirred evenly. The molar ratio of each substance in this precursor was molecular sieve: metal component source: water = 1.0:0.12:2.4. The resulting product was subjected to sealed aging treatment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0091] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 243 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatic yield of 52%. The catalyst composition is listed in Table 1.

[0092] Example 9

[0093] Following the method of Example 1, the ratio of the metal component source and water was changed. 297 g of zinc nitrate hexahydrate and 23.6 g of calcium nitrate tetrahydrate were added to 270 g of water to prepare a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% was added and stirred until homogeneous. The molar ratio of each substance in this precursor was molecular sieve: metal component source: water = 1.0:1.1:9.4. The resulting product was aged in a sealed environment at 80°C for 2.5 hours. The resulting solid was dried at 100°C for 37 hours. The resulting solid composite was calcined at 540°C for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0094] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle could reach 227 hours (based on a conversion rate greater than 85% of the initial conversion rate), with an aromatics yield of 58%. The catalyst composition is listed in Table 1.

[0095] Example 10

[0096] The method is the same as in Example 2, except that the sealed aging treatment is carried out in the presence of a carbon dioxide atmosphere at a pressure of 0.3 MPa.

[0097] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins, and the catalyst's single-pass operation cycle reached 290 hours (based on a conversion rate greater than 85% of the initial conversion rate). The aromatic yield was 91%. The catalyst composition and catalytic performance results are listed in Table 1.

[0098] Comparative Example 1

[0099] Following the steps in Example 1, without adding calcium nitrate tetrahydrate to the precursor, 29.7 g of zinc nitrate hexahydrate was added to 70 g of water to prepare a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was added and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.06:2.4. The resulting product was aged in a sealed environment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0100] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst had a single-pass operation cycle of 166 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 45%. The catalyst composition is listed in Table 1.

[0101] Comparative Example 2

[0102] Following the steps in Example 1, without adding zinc nitrate hexahydrate to the precursor, 47.6 g of calcium nitrate tetrahydrate was added to 70 g of water to prepare a mixture. 110 g of ZSM-5 molecular sieve with an aluminum content of 3.5% by weight was added and stirred evenly. The molar ratio of each substance in the precursor was molecular sieve: metal component source: water = 1.0:0.11:2.4. The resulting product was aged in a sealed environment at 80 degrees Celsius for 2.5 hours. The resulting solid was dried at 100 degrees Celsius for 37 hours. The resulting solid composite was calcined at 540 degrees Celsius for 15 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0103] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst had a single-pass operating cycle of only 155 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 27%. The catalyst composition is listed in Table 1.

[0104] Comparative Example 3

[0105] Following the steps in Example 4, the precursor is a mixture of chromium nitrate nonahydrate and zinc nitrate hexahydrate, without the addition of calcium nitrate tetrahydrate, to obtain a composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0106] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst had a single-pass operating cycle of only 186 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 40%. The catalyst composition is listed in Table 1.

[0107] Comparative Example 4

[0108] Following the steps in Example 4, the precursor is a mixture of calcium nitrate tetrahydrate and magnesium nitrate tetrahydrate, without the addition of zinc nitrate hexahydrate. 23.6 g of calcium nitrate tetrahydrate and 14.9 g of magnesium nitrate are mixed with 70 g of water to form a solution. 110 g of MCM-22 molecular sieve with an aluminum content of 3.8% by weight is taken and stirred evenly. The molar ratio of each substance in the precursor is molecular sieve: metal component source: water = 1.0:0.11:2.4. The resulting product is aged in a sealed environment at 80 degrees Celsius for 3 hours. The resulting solid is dried at 100 degrees Celsius for 30 hours. The resulting solid composite is calcined at 500 degrees Celsius for 14 hours under controlled temperature to obtain the composite metal oxide / molecular sieve, which is the aromatization catalyst.

[0109] The catalyst obtained in this example was used in the process of producing aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, the catalyst was reacted with C4 olefins. The catalyst had a single-pass operating cycle of only 183 hours (based on a conversion rate greater than 85% of the initial conversion rate), and the aromatic yield was 29%. The catalyst composition is listed in Table 1.

[0110] Table 1 Catalyst Composition of Examples and Comparative Examples

[0111]

[0112]

[0113] In summary, the zinc-calcium bimetallic supported catalyst used in this invention is effective in the catalytic synthesis of aromatics from C4 olefins at a reaction temperature of 500°C, a reaction pressure of 0.20 MPa, and a C4 olefin weight hourly space velocity of 0.5 h⁻¹. -1 Under certain conditions, when the catalyst is reacted with C4 olefins, the single-pass operation cycle of the catalyst can reach 275 hours (based on a conversion rate greater than 85% of the initial conversion rate). The catalyst prepared by impregnating molecular sieves with a single zinc oxide precursor has a single-pass operation cycle of only 166 hours (based on a conversion rate greater than 85% of the initial conversion rate). The single-pass operation cycle of the catalyst is improved by 65.5%, achieving better technical results.

[0114] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An aromatization catalyst, characterized in that, The catalyst contains, by weight fraction: a) 0.5-15 parts metal oxide; b) 85-99.5 parts molecular sieve; The metal oxide comprises an oxide of metal component 1 and an oxide of metal component 2, wherein the molar ratio of metal component 1 to metal component 2 is (0.25-8.0):1, metal component 1 is selected from one or more of zinc, gallium, molybdenum and chromium; metal component 2 is a group IIA element. The oxides of metal component 1 and metal component 2 exist in the form of a homogeneous complex; The aluminum content in the molecular sieve is 0.25-4.5% by weight. The method for preparing the catalyst includes: a) Molecular sieve, metal component 1 source, metal component 2 source, and water are used to form precursor A. The molar ratio of each substance in precursor A is molecular sieve: metal component source: water = 1: (0.01-0.25): (0.30-4.0). Except for water, the other components are calculated on a dry basis. b) Precursor A is subjected to sealed aging treatment and then dried to form precursor B; c) Calcining precursor B; The sealed aging process was carried out in the presence of a carbon dioxide atmosphere.

2. The catalyst according to claim 1, wherein, The metal component 2 is selected from magnesium and / or calcium; and / or The molar ratio of metal component 1 to metal component 2 is (0.45-7.5):

1.

3. The catalyst according to claim 1 or 2, wherein, The molecular sieve contains at least one of ten-membered rings and twelve-membered rings.

4. The catalyst according to claim 3, wherein, The molecular sieve is selected from any one or a mixture of two or more of the following: ZSM-5, ZSM-22, EU-1, MCM-22 and ZSM-11 silica-alumina molecular sieves containing ten-membered ring channels.

5. The catalyst according to claim 1 or 2, wherein, The aluminum content in the molecular sieve is 0.55-4.0 by weight.

6. The catalyst according to claim 5, wherein, The aluminum content in the molecular sieve is 0.75-4.0% by weight.

7. The catalyst according to claim 1 or 2, wherein, In step a), the molar ratio of each substance in precursor A is molecular sieve: metal component source: water = 1:(0.02-0.22):(0.30-4.0); and / or In step b), the conditions for the sealed aging treatment include a temperature of 15-85°C and / or a time of 2-45 hours.

8. The catalyst according to claim 7, wherein, In step a), the molar ratio of each substance in precursor A is molecular sieve: metal component source: water = 1:(0.03-0.20):(0.30-4.0); and / or In step b), the conditions for the sealed aging treatment include a temperature of 25-85°C and / or a time of 2-40 hours.

9. The catalyst according to claim 8, wherein, In step b), the conditions for the sealed aging treatment include a temperature of 35-85°C and / or a time of 2-35 hours.

10. The catalyst according to claim 1 or 2, wherein, In step b), the drying conditions include a temperature of 85-150°C and / or a time of 2-48 hours.

11. The catalyst according to claim 10, wherein, In step b), the drying conditions include a temperature of 90-140°C and / or a time of 2-45 hours.

12. The catalyst according to claim 11, wherein, In step b), the drying conditions include a temperature of 95-135°C and / or a time of 2-40 hours.

13. The catalyst according to claim 1 or 2, wherein, In step c), the calcination conditions include a temperature of 350-700℃ and / or a time of 2-42 hours.

14. The catalyst according to claim 1 or 2, wherein, Metal component 1 source and metal component 2 source are each selected from at least one of nitrate, carbonate, chloride, sulfate, molybdate, phosphate and acetate.

15. The use of the catalyst according to any one of claims 1-14 in the aromatic synthesis of aromatics from olefins, aromatics from methanol, or aromatics from alkanes.

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