A catalyst for preparing ethane and propane from heptane, its preparation method and application

Abstract

The application discloses a catalyst for preparing ethane and propane from heptane as well as a preparation method and application thereof. The catalyst comprises a molecular sieve carrier, a binding component and a modified component. The mass percentage of the molecular sieve carrier is 50-80% based on the total weight of the catalyst. The mass percentage of the binding component in terms of oxides is 17-35%. The mass percentage of the modified component in terms of oxides is 3-15%. The modified component comprises oxides of at least one metal selected from nickel, gallium, copper and zinc. The catalyst can efficiently convert heptane into ethane and propane, and has a high conversion rate of heptane and a high selectivity of ethane and propane at a low temperature.

Description

Technical Field

[0001] This invention belongs to the field of ethane and propane preparation technology, specifically relating to a catalyst for the production of ethane and propane from heptane, its preparation method, and its application. Background Technology

[0002] In recent years, as refining and chemical enterprises have continuously optimized their feedstocks, cracking feedstocks are trending towards lighter forms, shifting from naphtha to light hydrocarbons, petroleum gas, natural gas, and other gaseous resources. Lighter feedstock production routes offer advantages such as higher diene yields, lower costs, lower energy consumption, and less pollution. Diene yields using lighter feedstocks are more than double those using medium / heavy feedstocks. For example, when producing ethylene from lighter feedstocks, the main product is ethylene, with a yield exceeding 70 wt%, while the propylene yield from propane dehydrogenation processes is even higher, reaching over 80 wt%.

[0003] Currently, the world's main sources of light feedstocks are Middle Eastern natural gas and US shale gas. With the commissioning of new cracking units and the large-scale production of propane dehydrogenation projects in China, there will be a significant demand for light feedstocks, especially propane. As China's cracking feedstocks become lighter and its new energy industry rapidly develops, a large surplus of medium / heavy hydrocarbon resources will emerge. Therefore, developing a process technology to produce light feedstocks from medium / heavy hydrocarbons can not only expand the applications of medium / heavy hydrocarbon resources but also address the problem of insufficient supply of light feedstocks in China.

[0004] CN102806100A discloses a catalyst for producing propane and high-octane gasoline from butane. The catalyst comprises hydrogen-form mesoporous silica-alumina zeolite, achieving a propane yield of 25%–55%. CN110947417A discloses a catalyst for producing propane and gasoline from alkanes. This catalyst comprises a composite support and rare earth oxides in a content of 0.1 wt%–2.0 wt% based on the support. The composite support comprises 5 wt%–85 wt% ZSM-5 zeolite, 5 wt%–85 wt% MCM-41 zeolite, and 5 wt%–40 wt% alumina. This catalyst is used for the conversion of alkanes under non-hydrogen-dependent conditions, exhibiting a high propane yield and producing high-octane gasoline blending components as a byproduct.

[0005] Existing technologies for alkane cracking to propane primarily use hydrocarbons with lower carbon numbers as feedstocks, while technologies for directly producing ethane and propane from alkanes with higher carbon numbers are rarely reported. This is mainly because when using higher carbon number hydrocarbons as feedstocks, the cracking products contain more liquefied petroleum gas and aromatics, resulting in relatively low yields of ethane and propane. Therefore, developing a catalyst and application method suitable for producing propane and ethane from high carbon number hydrocarbon feedstocks is of great significance for research on the application of light feedstocks. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a catalyst for the production of ethane and propane from heptane, its preparation method, and its applications. This catalyst can efficiently convert heptane into ethane and propane, exhibiting high conversion rates for heptane and high selectivity for ethane and propane at relatively low temperatures.

[0007] A first aspect of the present invention provides a catalyst for the production of ethane and propane from heptane. The catalyst comprises: a molecular sieve support, a binder component, and a modifying component.

[0008] According to the present invention, the total weight of the catalyst is used as a basis.

[0009] The molecular sieve carrier has a mass percentage content of 50% to 80%, preferably 60% to 75%;

[0010] The binder component, calculated as oxides, has a mass percentage content of 17% to 35%, preferably 20% to 30%.

[0011] The modified component, calculated as an oxide, has a mass percentage of 3% to 15%, preferably 5% to 10%.

[0012] According to the present invention, the molecular sieve support is ZSM-5 molecular sieve. The ZSM-5 molecular sieve is in the hydrogen form. The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 30 to 200, preferably 50 to 150.

[0013] According to the present invention, the binder component is aluminum oxide, preferably γ-alumina.

[0014] According to the present invention, the modifying component comprises an oxide of at least one metal selected from nickel, gallium, copper and zinc.

[0015] According to the present invention, preferably, the modifying component comprises an oxide of nickel and an oxide selected from at least one metal selected from gallium, copper, and zinc. The mass ratio of the nickel oxide to the oxide selected from at least one metal selected from gallium, copper, and zinc is 1:1 to 3:1.

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, the method comprising the following steps:

[0017] Molecular sieve support, binder and kneading agent are mixed and shaped to obtain catalyst intermediate; then modified components are introduced and calcined to obtain the catalyst.

[0018] According to the present invention, the molding can be carried out in a conventional manner in the art, such as extrusion molding.

[0019] According to the present invention, after molding, the catalyst intermediate is dried and calcined to obtain the catalyst intermediate. The drying conditions include a temperature of 100℃ to 140℃ and a time of 5h to 30h. The calcination conditions include a temperature of 500℃ to 550℃ and a time of 2h to 18h.

[0020] According to the present invention, in the method for preparing the catalyst, drying may be performed before calcination. The drying conditions include: a temperature of 100℃ to 140℃ and a time of 5h to 30h.

[0021] According to the present invention, in the method for preparing the catalyst, the calcination conditions include: a temperature of 500℃ to 550℃ and a time of 4h to 18h.

[0022] According to the present invention, the adhesive component is derived from an adhesive. The adhesive is alumina and / or boehmite.

[0023] According to the present invention, the kneading agent is nitric acid. The amount of kneading agent added, based on nitric acid, is 1% to 5% of the mass of the molecular sieve carrier in the raw material. Before use, the nitric acid is first prepared into an aqueous solution with a mass concentration of 2.0 wt% to 7.5 wt%, and then mixed with the molecular sieve carrier and binder.

[0024] According to the present invention, the modifying component is derived from a modifier. The modifier is at least one of a metal nitrate, sulfate, and chloride in the modifying component.

[0025] According to the present invention, the modifier is introduced by impregnation. Specifically, the catalyst intermediate is impregnated with the modifier. The impregnation is preferably equal-volume impregnation. The impregnation temperature is 5–40°C. The impregnation time is 2–4 hours. After impregnation, drying and / or calcination can be performed. The drying conditions are: temperature 80°C–110°C, time 5–30 hours. The calcination conditions are: temperature 500°C–550°C, time 4–10 hours.

[0026] A third aspect of the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described method in the reaction of heptane to ethane and propane.

[0027] According to the present invention, the method of application includes reacting a feedstock comprising heptane and hydrogen with the catalyst.

[0028] According to the present invention, in the application described, the heptane is a seven-carbon n-alkane and / or iso-alkane.

[0029] According to the present invention, in the aforementioned application, the reaction conditions are: a reaction temperature of 200℃~500℃, preferably 250℃~450℃; and a heptane mass hourly space velocity of 0.2h. -1 ~2h -1 .

[0030] According to the present invention, in the aforementioned application, the reaction pressure is 0.2 MPa to 6 MPa, preferably 0.5 MPa to 3 MPa. Specific values ​​of the reaction pressure may be, for example, but not limited to, 0.25, 0.35, 0.4, 0.55, 0.7, 1, 2, 2.5, 4, 5, etc., MPa.

[0031] According to the present invention, the raw materials include heptane and hydrogen; preferably, the molar ratio of hydrogen to heptane in the raw materials is 0.1:1 to 2.0:1, more preferably 0.3:1 to 1.0:1. Specific values ​​for the molar ratio of hydrogen to heptane can be, for example, but not limited to, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.5, and 1.8.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. The catalyst of the present invention comprises: a molecular sieve support, a binder component, and a modifying component; based on the total weight of the catalyst, the molecular sieve support comprises 50% to 80% by mass; the binder component comprises 17% to 35% by mass (based on oxides); the modifying component comprises 3% to 15% by mass (based on oxides); the modifying component comprises an oxide of at least one metal selected from nickel, gallium, copper, and zinc. This catalyst can efficiently convert heptane into ethane and propane, exhibiting high conversion rate for heptane and selectivity for ethane and propane at relatively low temperatures.

[0034] 2. In the preparation method of the catalyst of the present invention, the preparation method includes: mixing a molecular sieve support, a binder, and a kneading agent, molding them, and obtaining a catalyst intermediate; then introducing a modifying component and calcining to obtain the catalyst. The catalyst prepared by the method can efficiently convert heptane into ethane and propane, exhibiting high conversion rate and ethane-propane selectivity.

[0035] 3. In the application of the catalyst of the present invention, the feed gas includes heptane and hydrogen. Under preferred conditions of pressure, catalyst, etc., the selectivity of ethane and propane can reach more than 60%, the selectivity of aromatics can be reduced to less than 20%, and the hydrogen consumption is low. In the application of the present invention, adding hydrogen to the feed gas, especially under a specific range of reaction pressure, is beneficial to improving the yield of ethane and propane and suppressing the formation of aromatic by-products. Detailed Implementation

[0036] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0037] Unless otherwise specified in the embodiments, the conventional conditions in this field shall apply.

[0038] In this invention, the composition of the catalyst is tested by elemental analysis (ICP).

[0039] In this invention, unless otherwise specified, all percentages are mass percentages.

[0040] In this invention, n-heptane is used as an example, and the specific formula is as follows:

[0041] n-Heptane conversion rate % = (n-Heptane feed mass - n-Heptane mass in product) / n-Heptane feed mass;

[0042] Ethane and propane selectivity % = Mass of ethane and propane products / Conversion of n-heptane;

[0043] Ethane and propane yield % = n-Heptane conversion % × Ethane and propane selectivity %;

[0044] Aromatic selectivity % = Mass of aromatic products / Conversion of n-heptane;

[0045] n-Heptane conversion rate = n-Heptane feed mass - n-Heptane mass in product.

[0046] In this invention, the various embodiments and comparative examples carried out the reaction of n-heptane to ethane and propane in a fixed-bed reactor under the following operating conditions: n-heptane as the raw material, reaction temperature of 350°C, and mass hourly space velocity of n-heptane of 0.6 h⁻¹. -1 The remaining reaction conditions and reaction results after 5 hours of catalyst reaction for each example are shown in Table 1.

[0047] In this invention, the room temperature is 20°C in each example. The impregnation described in each example is equal-volume impregnation.

[0048] Example 1

[0049] 120.0 g of hydrogen-form ZSM-5 molecular sieve powder with a SiO2 / Al2O3 molar ratio of 50 was mixed evenly with 40 g of pseudoboehmite. A solution was prepared by mixing 3.5 mL of nitric acid (65 wt%) and 60 mL of water. This solution was added to the mixture of ZSM-5 molecular sieve and pseudoboehmite, kneaded and extruded into strips, dried at 110 °C overnight (12 h), and calcined at 540 °C for 4 h to obtain the catalyst intermediate.

[0050] Prepare a solution by dissolving 4 g of nickel nitrate, 3 g of zinc nitrate, and 50 mL of water. Add this solution to the catalyst intermediate, impregnate at room temperature for 2 hours, then filter, dry at 100°C for 10 hours, and calcine at 530°C for 6 hours. The resulting catalyst is designated as catalyst A.

[0051] The catalyst A has the following composition: 70.7 wt% ZSM-5, 23.5 wt% alumina, 2.3 wt% zinc oxide, and 3.5 wt% nickel oxide.

[0052] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0053] Example 2

[0054] 90.0 g of hydrogen-form ZSM-5 molecular sieve powder with a SiO2 / Al2O3 molar ratio of 100 was mixed evenly with 36 g of pseudoboehmite. A solution was prepared by mixing 2.6 mL of nitric acid (65 wt%) and 50 mL of water. This solution was added to the mixture of ZSM-5 molecular sieve and pseudoboehmite, mixed evenly, kneaded and extruded into strips, dried at 110 °C overnight for 12 h, and calcined at 550 °C for 3 h.

[0055] A solution was prepared using 4.5 g of nickel nitrate, 3 g of copper nitrate, and 40 mL of water. This solution was added to the prepared catalyst intermediate and impregnated at room temperature for 3 hours. The mixture was then filtered, dried at 90°C for 20 hours, and calcined at 530°C for 6 hours. The resulting catalyst was designated as Catalyst B.

[0056] The catalyst B has the following composition: 65.5 wt% ZSM-5, 25.9 wt% alumina, 5.4 wt% nickel oxide, and 3.2 wt% copper oxide.

[0057] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0058] Example 3

[0059] The only difference between this embodiment and Example 1 is that the specifications of the ZSM-5 molecular sieve powder used are: SiO2 / Al2O3 molar ratio of 120. Under the same conditions as in Example 1, catalyst C was prepared.

[0060] The C catalyst composition is: 70.6 wt% ZSM-5, 23.5 wt% alumina, 2.4 wt% zinc oxide, and 3.5 wt% nickel oxide.

[0061] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0062] Example 4

[0063] The only difference between this embodiment and Example 1 is that the specifications of the ZSM-5 molecular sieve powder used are: SiO2 / Al2O3 molar ratio of 85. Under the same conditions as in Example 1, catalyst D was prepared.

[0064] The catalyst composition is: 70.5 wt% ZSM-5, 23.7 wt% alumina, 2.2 wt% zinc oxide, and 3.6 wt% nickel oxide.

[0065] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0066] Example 5

[0067] The carrier and binder used were the same as in Example 2. The catalyst intermediate was prepared under the same conditions as in Example 2.

[0068] A solution was prepared using 5 g of nickel nitrate, 3 g of gallium nitrate, and 40 mL of water. This solution was added to a pre-formed catalyst intermediate and impregnated at room temperature for 3 hours. The mixture was then filtered, dried at 100°C for 8 hours, and calcined at 530°C for 6 hours. The resulting catalyst was denoted as catalyst E.

[0069] The E catalyst composition is: 65.7 wt% ZSM-5, 25.3 wt% aluminum oxide, 5.8 wt% nickel oxide, and 3.2 wt% gallium oxide.

[0070] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0071] Example 6

[0072] The carrier and binder used were the same as in Example 2. The catalyst intermediate was prepared under the same conditions as in Example 2.

[0073] A solution was prepared using 4 g of nickel nitrate, 4 g of zinc nitrate, and 40 mL of water. This solution was added to the prepared catalyst intermediate and impregnated at room temperature for 3 hours. The mixture was then filtered, dried at 100°C for 8 hours, and calcined at 530°C for 6 hours. The resulting catalyst was denoted as catalyst F.

[0074] The F catalyst composition is: 65.8 wt% ZSM-5, 25.5 wt% alumina, 4.5 wt% nickel oxide, and 4.2 wt% zinc oxide.

[0075] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0076] Example 7

[0077] The carrier and binder used were the same as in Example 2. The catalyst intermediate was prepared under the same conditions as in Example 2.

[0078] A solution was prepared using 4 g of nickel nitrate, 1.5 g of zinc nitrate, and 40 mL of water. This solution was added to the prepared catalyst intermediate and impregnated at room temperature for 3 hours. The mixture was then filtered, dried at 100°C for 8 hours, and calcined at 530°C for 6 hours. The resulting catalyst was denoted as catalyst G.

[0079] The G catalyst composition is: 67.9 wt% ZSM-5, 26.3 wt% alumina, 4.3 wt% nickel oxide, and 1.5 wt% zinc oxide.

[0080] The results of the catalyst's testing and evaluation in a fixed-bed reactor for the production of ethane and propane from heptane are shown in Table 1.

[0081] Comparative Example 1

[0082] Similar to Example 1, except that the reaction pressure in this application is 0.1 MPa. The reaction results show that adjusting the reaction pressure significantly reduces the yield of ethane and propane, particularly affecting the conversion rate of n-heptane.

[0083] Comparative Example 2

[0084] Similar to Example 1, except that the feed gas in this application does not contain hydrogen. The reaction results show that when the feed gas does not contain hydrogen, the yields of ethane and propane are significantly reduced, and the selectivity for aromatic byproducts is greatly increased.

[0085] Table 1

[0086]

[0087] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. The application of a catalyst for the production of ethane and propane from heptane in the reaction of heptane to ethane and propane, characterized in that, The catalyst for the production of ethane and propane from heptane comprises: a molecular sieve support, a binder component, and a modifying component; based on the total weight of the catalyst, The molecular sieve carrier has a mass percentage content of 50% to 80%; The binder component, calculated as oxides, has a mass percentage content of 17% to 35%. The modified component has a mass percentage of 3% to 15% based on oxides; The modifying component includes an oxide of at least one metal selected from nickel, gallium, copper, and zinc.

2. The application according to claim 1, characterized in that, The raw materials include heptane and hydrogen.

3. The application according to claim 2, characterized in that, The molar ratio of hydrogen to heptane is 0.1:1 to 2.0:

1.

4. The application according to claim 3, characterized in that, The molar ratio of hydrogen to heptane is 0.3:1 to 1.0:

1.

5. The application according to any one of claims 1 to 4, characterized in that, In the aforementioned applications, the reaction pressure is 0.2 MPa to 6 MPa.

6. The application according to claim 5, characterized in that, In the aforementioned applications, the reaction pressure is 0.5 MPa to 3 MPa.

7. The application according to claim 1, characterized in that, In this application, the reaction conditions are: reaction temperature of 200℃~500℃; and heptane mass hourly space velocity of 0.2 h⁻¹. -1 ~2h -1 .

8. The application according to claim 7, characterized in that, In this application, the reaction temperature is 250℃~450℃.

9. The application according to claim 1, characterized in that, Based on the total weight of the catalyst, The molecular sieve carrier has a mass percentage content of 60%~75%; The binder component, calculated as oxides, has a mass percentage content of 20% to 30%. The modified component has a mass percentage of 5% to 10% based on oxides.

10. The application according to claim 1, characterized in that, The modifying components include oxides of nickel and oxides of at least one metal selected from gallium, copper, and zinc.

11. The application according to claim 10, characterized in that, The mass ratio of nickel oxide to oxide of at least one metal selected from gallium, copper and zinc is 1:1 to 3:

1.

12. The application according to claim 1, characterized in that, The molecular sieve support is ZSM-5 molecular sieve; and / or, the binder component is alumina.

13. The application according to claim 12, characterized in that, The binder component is γ-alumina.

14. The application according to claim 1, characterized in that, The method for preparing the catalyst includes the following steps: Molecular sieve support, binder and kneading agent are mixed and shaped to obtain catalyst intermediate; then modified components are introduced and calcined to obtain the catalyst.

15. The application according to claim 14, characterized in that, In the catalyst preparation method, the calcination conditions include: a temperature of 500℃~550℃ and a time of 4h~18h.

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