Gas phase cracking catalyst, process for its preparation and use

Abstract

This invention relates to the field of catalysts, and discloses a gas-phase cracking catalyst, its preparation method, and its application. The catalyst comprises, by weight, 1.5-20 parts of an active component and 80-98.5 parts of a support; the active component is selected from one or more elements of Group IIB, Group IIIA, Group IVA, and Group VA; the active component exists in elemental and / or oxide form; the support is selected from one or more molecular sieves of type ZSM-5, Y-type, and X-type. The catalyst of this invention exhibits high catalytic activity, few byproducts, and high stability in the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropylene, showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a gas-phase cracking catalyst, its preparation method, and its application. Background Technology

[0002] 2-Methoxypropene is an important pharmaceutical intermediate widely used in the synthesis of clarithromycin, pseudoviolet, vitamins, carotene, and other substances. Due to its huge demand, researching and developing simple, efficient, and large-scale industrially scalable methods for synthesizing 2-methoxypropene is of paramount importance.

[0003] Currently, the main methods for synthesizing 2-methoxypropylene include direct synthesis and liquid-phase or gas-phase cracking. While the direct synthesis method, which involves nucleophilic addition of methanol and unsaturated hydrocarbons to obtain 2-methoxypropylene, is simple, it suffers from drawbacks such as the difficulty in obtaining reactants, the intense and uncontrollable reaction process, and the significant corrosive effects of the required catalyst on production equipment. Cracking refers to the removal of one molecule of methanol from 2,2-dimethoxypropane at high temperatures and with the aid of a catalyst to obtain the product 2-methoxypropylene. Liquid-phase cracking, using inorganic or organic acids as homogeneous catalysts, requires expensive solvents and anhydrides, and post-reaction processing is also cumbersome. Gas-phase cracking, on the other hand, offers higher conversion rates and selectivity, and the resulting cracked liquid has a relatively simple composition and is easy to separate, making it a more cost-effective and feasible synthesis method. Developing catalyst systems with high catalytic activity and stability is one of the key issues in gas-phase cracking.

[0004] Catalysts suitable for this reaction include metal phosphates, acidic ceramics, heteropoly acids, cationic resins, and molecular sieves. Patent US5767325 uses a self-made ZSM-5 as a gas-phase cracking catalyst to prepare 2-methoxypropylene at a reaction temperature of 280-340℃, achieving a product yield of 83.3%. CN1660742A compares different types of catalysts, showing that acidic molecular sieves exhibit lower activity than heteropoly acids and acidic ceramics. Therefore, modifying molecular sieve catalysts to improve their reactivity and stability is a feasible approach for designing and developing catalysts for the gas-phase cracking synthesis of 2-methoxypropylene. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor reaction performance and poor stability of existing gas phase cracking catalysts, and to provide a gas phase cracking catalyst, its preparation method and application. This gas phase cracking catalyst has the characteristics of high conversion rate, high selectivity and good stability.

[0006] To achieve the above objectives, the present invention provides a gas-phase cracking catalyst, wherein the catalyst comprises, by weight, 1.5-20 parts of an active component and 80-98.5 parts of a support; the active component is selected from one or more elements of Group IIB, Group IIIA, Group IVA, and Group VA; the active component exists in the form of an element and / or an oxide; and the support is selected from one or more molecular sieves of type ZSM-5, type Y, and type X.

[0007] A second aspect of the present invention provides a method for preparing the catalyst described herein, the method comprising:

[0008] 1) Obtain a carrier;

[0009] 2) The active component source solution is impregnated and brought into contact with the carrier;

[0010] 3) Drying and calcining.

[0011] A third aspect of the present invention provides the application of the catalyst described herein in the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropylene; preferably, the reaction conditions include: a reaction temperature of 160-250°C; a catalyst loading of 10-60 g; and a 2,2-dimethoxypropane gas flow rate of 0.5-4.0 mL / min.

[0012] The catalyst of this invention has the characteristics of high conversion rate, high selectivity and good stability when applied to gas-phase cracking reactions, such as the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropylene. Detailed Implementation

[0013] 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.

[0014] This invention provides a gas-phase cracking catalyst, which comprises, by weight, 1.5-20 parts of active component and 80-98.5 parts of support; the active component is selected from one or more elements of Group IIB, Group IIIA, Group IVA, and Group VA; the active component exists in the form of element and / or oxide; the support is selected from one or more molecular sieves of type ZSM-5, type Y, and type X.

[0015] According to a particularly preferred embodiment of the present invention, the catalyst comprises, by weight, 2-12 parts of an active component and 88-98 parts of a support. By adopting the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0016] According to a particularly preferred embodiment of the present invention, the active component element is selected from one or more of Zn, In, Sn, and Sb metal oxides, preferably In and / or Sb. By adopting the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0017] According to a particularly preferred embodiment of the present invention, the support is a ZSM-5 type molecular sieve, preferably Zn-ZSM-5, and more preferably, the zinc oxide content in the molecular sieve is 2% to 40% of the total weight of the molecular sieve. By adopting the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0018] In this invention, when Zn-ZSM-5 molecular sieve is used as a catalyst support, the content of its active component is calculated based on the content of Zn excluding the Zn content in the Zn-ZSM-5 molecular sieve, but this invention is not limited to this.

[0019] In this invention, catalysts possessing the aforementioned characteristics can achieve the objectives of this invention. There are no particular requirements for the preparation method of the catalyst. According to a preferred embodiment of this invention, the preparation method of the catalyst includes:

[0020] 1) Obtain a carrier;

[0021] 2) The active component source solution is impregnated and brought into contact with the carrier;

[0022] 3) Drying and calcining.

[0023] In this invention, the drying conditions in step 3) can be conventional choices in the art. According to a preferred embodiment of the invention, the drying conditions include: a temperature of 60-120°C and a time of 5-20 hours. By adopting the aforementioned preferred scheme, the activity of the catalyst can be further improved.

[0024] In this invention, the calcination conditions in step 3) can be conventionally chosen in the art. According to a preferred embodiment of the invention, the calcination conditions include: a temperature of 400-800℃ and a time of 2-10 hours. By adopting the aforementioned preferred scheme, the activity of the catalyst can be further improved.

[0025] In this invention, the types of active component sources can be selected from a wide range. According to a preferred embodiment of the invention, the active component source is selected from one or more of indium nitrate, tin acetate, and antimony acetate. By employing the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0026] To further improve the activity of the catalyst, according to a preferred embodiment of the present invention, the active component source is a mixed solution of indium nitrate and antimony acetate, and the molar ratio of indium nitrate to antimony acetate is (0.5-2):1, including but not limited to 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, etc.

[0027] In this invention, as long as the objective of this invention can be achieved, the method for preparing the carrier in step 1) according to a preferred embodiment of this invention includes:

[0028] a) Thoroughly mix the zinc salt with the H-ZSM-5 molecular sieve powder;

[0029] b) Grinding and calcining.

[0030] This invention uses a solid-phase ion exchange method to prepare Zn-ZSM-5 support, which can further improve the activity of the catalyst.

[0031] In this invention, the grinding conditions described in step b) can be conventional choices in the art. According to a preferred embodiment of the invention, the grinding conditions described in step b) include a time of 1-5 hours. By adopting the aforementioned preferred scheme, the activity of the catalyst can be further improved.

[0032] In this invention, the conditions for high-temperature calcination in step b) can be conventionally chosen in the art. According to a preferred embodiment of this invention, the conditions for high-temperature calcination in step b) include: a temperature of 400-800°C and a time of 2-10 hours. By adopting the aforementioned preferred scheme, the activity of the catalyst can be further improved.

[0033] In this invention, as long as the objective of the invention is achieved, there are no particular requirements for the silicon-to-aluminum ratio of the H-ZSM-5 molecular sieve. According to a preferred embodiment of the invention, the silicon-to-aluminum ratio of the H-ZSM-5 molecular sieve is 20-500. By adopting the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0034] The silicon-aluminum ratio mentioned in this invention refers to the molar ratio of silicon dioxide to aluminum oxide.

[0035] In this invention, as long as the objective of the invention can be achieved, there are no special requirements for the specific surface area of ​​the H-ZSM-5 molecular sieve. According to a preferred embodiment of the invention, the specific surface area of ​​the H-ZSM-5 molecular sieve is 300-650 m². 2 / g. By adopting the aforementioned preferred scheme, the activity of the catalyst can be further improved.

[0036] In this invention, a wide variety of zinc salts can be selected. According to a preferred embodiment of the invention, the zinc salt is selected from one or more of zinc oxide, zinc chloride, and zinc acetate, preferably zinc acetate. By employing the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0037] To further improve the activity of the catalyst, according to a preferred embodiment of the present invention, the mass ratio of the zinc salt to the H-ZSM-5 molecular sieve is 1:(2-15), including but not limited to 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, etc.

[0038] This invention provides the application of the catalyst described in this invention and / or the catalyst prepared by the preparation method described in this invention in the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropylene.

[0039] According to a preferred embodiment of the present invention, the reaction conditions include: a reaction temperature of 160-250°C; a catalyst loading of 10-60 g; and a 2,2-dimethoxypropane gas flow rate of 0.5-4.0 mL / min.

[0040] The catalyst prepared by the method described in this invention is used in the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropylene, and has the characteristics of high catalytic activity, few by-products, and high stability.

[0041] The present invention will be further described below through specific embodiments. The scope of the present invention is not limited to the scope covered by the embodiments. The catalyst evaluation method is as follows:

[0042] The obtained catalyst was compressed into tablets, crushed, and sieved to obtain particles of 60-80 mesh. These particles were then used in the gas-phase cracking of 2,2-dimethoxypropane to synthesize 2-methoxypropene. The reaction equation is as follows:

[0043]

[0044] The specific reaction evaluation steps and conditions include: placing 30g of catalyst in a fixed-bed reactor; introducing 2,2-dimethoxypropane gas at a flow rate of 2.7mL / min; carrying out the reaction at 200℃; and performing chromatographic analysis on the condensate after passing through the fixed bed to obtain the conversion rate and selectivity of 2-methoxypropene.

[0045] Example 1

[0046] H-ZSM-5 molecular sieve was used, with a silica-to-alumina ratio of 46 and a specific surface area of ​​355 m². 2 / g. Zinc acetate and H-ZSM-5 were thoroughly mixed, with a mass ratio of zinc acetate to H-ZSM-5 of 1:4.5. After grinding the mixture for 2 hours, it was calcined in a muffle furnace at 500℃ for 6 hours. The calcined Zn-ZSM-5 support was then impregnated with antimony acetate solution to achieve a loading of 5 wt.% for the active component Sb₂O₃. The impregnated catalyst was dried at 80℃ for 10 hours and then calcined in a muffle furnace at 500℃ for 6 hours. Tests were performed, and the results are shown in Tables 1 and 2.

[0047] Example 2

[0048] H-ZSM-5 molecular sieve was used, with a silica-to-alumina ratio of 20:1 and a specific surface area of ​​352 m². 2 / g. Zinc acetate and H-ZSM-5 were thoroughly mixed, with a mass ratio of zinc acetate to H-ZSM-5 of 1:4.5. After grinding the mixture for 2 hours, it was calcined in a muffle furnace at 500℃ for 6 hours. The calcined Zn-ZSM-5 support was then impregnated with tin acetate solution to achieve a SnO2 loading of 5 wt.%. The impregnated catalyst was dried at 80℃ for 10 hours and then calcined in a muffle furnace at 500℃ for 6 hours. The results are shown in Tables 1 and 2.

[0049] Example 3

[0050] H-ZSM-5 molecular sieve was used, with a silica-to-alumina ratio of 120 and a specific surface area of ​​357 m². 2 / g. Zinc acetate and H-ZSM-5 were thoroughly mixed, with a mass ratio of zinc acetate to H-ZSM-5 of 1:4.5. After grinding the mixture for 2 hours, it was calcined in a muffle furnace at 500℃ for 6 hours. The calcined Zn-ZSM-5 support was then impregnated with indium nitrate solution to achieve an active component In2O3 loading of 12 wt.%. The impregnated catalyst was dried at 80℃ for 10 hours and then calcined in a muffle furnace at 500℃ for 6 hours. Tests were performed, and the results are shown in Tables 1 and 2.

[0051] Example 4

[0052] The method of Example 1 was followed, except that a mixed solution of indium nitrate and antimony acetate (molar ratio of 1:1) was impregnated to achieve a loading of 5 wt.% for the active component In₂O₃ + Sb₂O₃. Other steps were the same as in Example 1. Tests were conducted, and the results are shown in Tables 1 and 2.

[0053] Example 5

[0054] The method is the same as in Example 1, except that a Y-type molecular sieve is used, with a silica-to-alumina ratio of 5.5 and a specific surface area of ​​735 m². 2 / g, other steps are the same as in Example 1. Tests were conducted, and the results are shown in Tables 1 and 2.

[0055] Example 6

[0056] Following the method of Example 1, except that zinc acetate was not added for solid-phase ion exchange to prepare the Zn-ZSM-5 support, and instead, H-ZSM-5 molecular sieves (of the same mass as the Zn-ZSM-5 support in Example 1) were directly impregnated with antimony acetate solution. Other steps were the same as in Example 1. Tests were performed, and the results are shown in Tables 1 and 2.

[0057] Example 7

[0058] The method of Example 1 was followed, except that the Zn-ZSM-5 support was not prepared by solid-phase ion exchange. Instead, H-ZSM-5 molecular sieve was used as the support to directly impregnate a solution of zinc acetate and antimony acetate. The amount of raw materials and other steps were the same as in Example 1. Tests were conducted, and the results are shown in Tables 1 and 2.

[0059] Example 8

[0060] The method of Example 1 was followed, except that zinc acetate was replaced with zinc oxide, and the mass ratio of zinc oxide to H-ZSM-5 was 1:19. Other steps were the same as in Example 1. Tests were conducted, and the results are shown in Tables 1 and 2.

[0061] Example 9

[0062] The method of Example 1 was followed, except that antimony acetate was replaced with ammonium metatungstate, and the carrier was impregnated with ammonium metatungstate solution to achieve an active component loading of 10 wt.%. Other steps were the same as in Example 1. Tests were conducted, and the results are shown in Tables 1 and 2.

[0063] Comparative Example 1

[0064] H-ZSM-5 molecular sieve was used as the catalyst, with a silica-to-alumina ratio of 46 and a specific surface area of ​​355 m². 2 / g. The test was conducted, and the results are shown in Tables 1 and 2.

[0065] Comparative Example 2

[0066] H-ZSM-5 molecular sieve was used, with a silica-to-alumina ratio of 46 and a specific surface area of ​​355 m². 2 / g. A certain amount of zinc acetate was thoroughly mixed with H-ZSM-5, wherein the mass ratio of zinc acetate to H-ZSM-5 was 1:4.5. After grinding the mixture for 2 hours, it was calcined in a muffle furnace at 500℃. Tests were performed, and the results are shown in Tables 1 and 2.

[0067] Comparative Example 3

[0068] The purchased sulfonic acid-modified acidic ceramics, with an acid concentration of 0.5 mmol / g, were used for testing. The results are shown in Tables 1 and 2.

[0069] Table 1. Conversion and selectivity of the catalyst in the synthesis of 2-methoxypropylene at 0.5 h.

[0070] Conversion rate (%) Selectivity (%) Example 1 79 95 Example 2 79 96 Example 3 77 98 Example 4 80 97 Example 5 69 91 Example 6 76 93 Example 7 72 92 Example 8 75 95 Example 9 70 94 Comparative Example 1 59 92 Comparative Example 2 65 96 Comparative Example 3 75 94

[0071] Table 2. Changes in catalyst conversion over time in the synthesis of 2-methoxypropylene.

[0072]

[0073] 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. The application of a gas-phase cracking catalyst in the gas-phase cracking synthesis of 2-methoxypropylene from 2,2-dimethoxypropane; said gas-phase cracking catalyst comprising, by weight: 1.5-20 parts active ingredient, 80-98.5 parts carrier; The active component element is either In or Sb, or the active component element is Sn; the active component exists in the form of an oxide. The carrier is selected from Zn-ZSM-5 molecular sieve.

2. The application according to claim 1, wherein, The catalyst comprises, by weight, 2-12 parts of active component and 88-98 parts of support.

3. The application according to claim 1, wherein, The active component elements are selected from In and Sb.

4. The application according to claim 1, wherein, The zinc oxide content in the molecular sieve is 2-40% of the total weight of the molecular sieve.

5. The application according to any one of claims 1-4, wherein the method for preparing the gas-phase cracking catalyst comprises: 1) Obtain a carrier; 2) The active component source solution is impregnated and brought into contact with the carrier; 3) Drying and calcining.

6. The application according to claim 5, wherein, The drying conditions described in step 3) include: a temperature of 60-120℃ and a time of 5-20 h; and / or The calcination conditions described in step 3) include: a temperature of 400-800℃ and a time of 2-10 h.

7. The application according to claim 5, wherein, The active component source is selected from indium nitrate and antimony acetate, or the active component source is selected from tin acetate.

8. The application according to claim 7, wherein, The active component sources are indium nitrate and antimony acetate, and the molar ratio of indium nitrate to antimony acetate is (0.5-2):

1.

9. The application according to claim 5, wherein, The method for preparing the carrier in step 1) includes: a) Thoroughly mix the zinc salt with the H-ZSM-5 molecular sieve powder; b) Grinding and calcination.

10. The application according to claim 9, wherein, In step b), The grinding conditions include: a grinding time of 1-5 hours; and / or The calcination conditions include a temperature of 400-800℃ and a time of 2-10 h.

11. The application according to claim 9, wherein, The H-ZSM-5 molecular sieve has a silica-to-alumina ratio of 20-500, and / or The specific surface area of ​​the H-ZSM-5 molecular sieve is 300-650 m². 2 / g; and / or The zinc salt is selected from one or more of zinc chloride and zinc acetate; and / or The mass ratio of the zinc salt to the H-ZSM-5 molecular sieve is 1:(2-15).

12. The application according to claim 11, wherein, The zinc salt is selected from zinc acetate.

13. The application according to claim 1, wherein, The reaction conditions include: a temperature of 160-250℃; a catalyst loading of 10-60g; and a 2,2-dimethoxypropane gas flow rate of 0.5-4.0 mL / min.

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