Isomerization catalyst as well as preparation method and application thereof

Abstract

The invention provides an isomerization catalyst as well as a preparation method and application thereof. The method comprises the following steps: kneading ZrO2-SO4 < 2->, phosphorus molybdenum tungsten heteropoly acid and pseudo-boehmite to obtain a mixture; kneading the mixture and the nitric acid aqueous solution to obtain clinker; carrying out extrusion molding, drying and roasting on the clinker to obtain a superacid carrier; putting the superacid carrier and the metal compound solution into a reaction kettle, pressurizing, relieving pressure, drying and roasting to obtain the isomerization catalyst, wherein the metal compound solution comprises a metal compound and water, and the metal compound comprises one or more of metal halide, metal sulfate, metal nitrate, metal acetate and metal oxalate. The high-pressure impregnation method is introduced to optimize the distribution of acidic sites of the superacid carrier, so that efficient, stable and environment-friendly preparation of the catalyst is realized.

Description

Technical Field

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

[0002] In petroleum refining and chemical production, isomerization is a crucial method for improving fuel quality and the added value of chemicals. For example, the isomerization of light alkanes (such as n-pentane and n-hexane) can generate branched alkanes, significantly increasing the octane number of gasoline, improving combustion performance, and reducing environmental pollution. With the continued growth of global energy demand and increasingly stringent environmental regulations, the need for efficient, stable, and environmentally friendly isomerization catalysts is becoming increasingly urgent. Isomerization reactions involve carbon chain rearrangement and typically require the action of acidic catalysts. The performance of these catalysts directly affects the conversion rate, selectivity, and economics of the reaction. Traditionally, the development of isomerization catalysts has evolved from liquid acids to solid acids, but many challenges remain, such as insufficient activity, short lifespan, and environmental pollution. Traditional isomerization catalysts mainly include supported noble metal catalysts, such as platinum (Pt) or palladium (Pd) supported on aluminum chloride or zeolite supports. While these catalysts exhibit certain activity in industrial applications, they suffer from several limitations. First, aluminum chloride-based catalysts readily generate corrosive byproducts, such as hydrochloric acid, leading to equipment corrosion and environmental pollution. This corrosion not only increases maintenance costs but also fails to meet the requirements of modern green chemistry. Second, although zeolite supports offer good shape selectivity, their acidic site strength is limited, making them prone to deactivation under high temperature or high steam conditions, resulting in short catalyst lifetimes. Furthermore, existing preparation methods often involve complex high-temperature calcination or fluorination processes, which are not only energy-intensive but may also introduce harmful fluorides, increasing production costs and safety risks. These problems limit the application of traditional catalysts in large-scale industrial production, thus necessitating the development of a corrosion-resistant, highly stable, and energy-efficient alternative material. In recent years, superacid materials (such as solid superacids, including zirconium oxide sulfate, zirconium tungstate, and antimony fluoride composites) have attracted much attention due to their extremely high acid strength (Hammett acidity function H0 can reach -16 or lower) and good thermal stability. These materials can mimic the catalytic performance of liquid superacids while avoiding the corrosion and separation problems of liquid acids. The introduction of superacid supports provides a new pathway for isomerization catalysts, enabling efficient isomerization at lower temperatures, reducing energy consumption and byproduct formation. Currently, existing superacid materials suffer from uneven distribution of acidic sites, which makes it difficult to optimize the activity and selectivity of the catalysts. Therefore, it is urgent to develop a method to overcome these shortcomings. Summary of the Invention

[0003] This invention addresses the problem of uneven distribution of acidic sites on the support by providing an isomerization catalyst, its preparation method, and its application.

[0004] The technical method of the present invention is as follows: A method for preparing an isomerization catalyst, the method comprising: S1, ZrO2-SO4 2- The mixture is obtained by kneading phosphomolybdenum tungsten heteropoly acid and pseudoboehmite. S2. Knead the mixture with the nitric acid aqueous solution to obtain the clinker; S3. Extrude the clinker into a mold, dry it, and calcine it to obtain a super acid carrier; S4. The superacid support and the metal compound solution are placed in a reaction vessel and subjected to pressure, depressurization, drying and calcination to obtain the isomerization catalyst; wherein, the metal compound solution includes metal compound and water, and the metal compound includes one or more of metal halide, metal sulfate, metal nitrate, metal acetate and metal oxalate.

[0005] The ZrO2-SO4 2- The mass ratio of phosphomolybdic tungsten heteropoly acid, pseudoboehmite, and nitric acid aqueous solution is 60~80:40~60:5~10:16~20; the concentration of the nitric acid aqueous solution is 10%~50%.

[0006] In step S1, the kneading time is 20-50 minutes.

[0007] In step S2, the kneading time is 20-40 minutes.

[0008] In step S3, the drying temperature is 80-120℃, and the drying time is 6-10 hours; the calcination temperature is 500-600℃, and the calcination time is 6-10 hours. The specific surface area of ​​the superacid carrier is 200-240 m². 2 / g, with a strength of 160~170 N / cm.

[0009] In step S4, the metal in the metal compound includes one or more of platinum, palladium, barium, yttrium, and lanthanum. The mass ratio of the superacid support, the metal compound, and water is 8~10:1:5~7.

[0010] In step S4, the pressure is increased to 0.5~3 MPa and maintained for 2~6 hours before being released. During the pressurization process, the stirrer in the reactor stirs the superacid carrier and the metal compound solution at a speed of 8~12 r / min. Drying includes vacuum drying and heating drying at a temperature of 70~90℃ for 4~8 hours. Calcination is carried out at a temperature of 500~700℃ for 6~10 hours. Here, the pressure parameter is set to 0.5~3 MPa, which matches the standard operating pressure of conventional chemical reactors, eliminating the need for custom-designed high-pressure equipment and reducing equipment investment costs for industrial applications. However, pressures below 0.5 MPa are insufficient to overcome the capillary resistance within the micropores / mesopores of the carrier, hindering sufficient solution penetration and failing to achieve the desired wetting effect. Pressures above 3 MPa, while potentially slightly increasing the wetting rate, significantly raise the pressure resistance requirements of the equipment, leading to a substantial increase in equipment procurement and maintenance costs, and the benefit to the wetting effect has no practical engineering value. The time parameter is set to 2-6 hours, which balances "adequacy of wetting" and "process efficiency". If the time is less than 2 hours, the solution cannot fully penetrate into the internal pores of the carrier, resulting in uneven loading of active components and failing to meet the wetting requirements of subsequent catalytic reactions. If the time is more than 6 hours, the wetting effect is close to saturation. Further extending the time will not only fail to improve performance but will also increase the production cycle, reduce the output per unit time, and waste time and energy.

[0011] The present invention provides an isomerization catalyst, which is obtained by the above-described method for preparing the isomerization catalyst.

[0012] This invention provides an application of an isomerization catalyst in alkane isomerization reactions.

[0013] The beneficial effects of this invention are: I. This invention optimizes the acidic site distribution of the superacid support by introducing a high-pressure impregnation method, thereby achieving efficient, stable and environmentally friendly catalyst preparation.

[0014] II. The catalyst of this invention is applied to alkane isomerization reactions, especially for the isomerization reactions of light alkanes such as n-pentane and n-hexane, to generate branched alkanes, thereby improving the octane number of gasoline and fuel performance. Detailed Implementation

[0015] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In a first aspect, the present invention provides a method for preparing an isomerization catalyst, the method comprising: S1, ZrO2-SO4 2- Phosphomolybdenum tungsten heteropoly acid and pseudoboehmite are kneaded together to obtain a mixture.

[0017] In one embodiment, the kneading time is 20 to 50 minutes. For example, the kneading time can be 30 minutes, 35 minutes, 40 minutes, or 45 minutes.

[0018] S2. Knead the mixture with nitric acid solution to obtain a cooked product.

[0019] In one embodiment, ZrO2-SO4 2- The mass ratio of phosphomolybdic acid, pseudoboehmite, and nitric acid aqueous solution is 60~80:40~60:5~10:16~20. For example, ZrO2-SO4 2- The mass ratio of phosphomolybdenum tungsten heteropoly acid, pseudoboehmite, and nitric acid aqueous solution can be 65:45:6:17, 70:50:7:18, or 75:55:9:19.

[0020] In one embodiment, the concentration of the nitric acid aqueous solution is 10% to 50%. For example, the concentration of the nitric acid aqueous solution may be 20%, 30%, or 40%.

[0021] In one embodiment, the kneading time is 20 to 40 minutes. For example, the kneading time can be 25 minutes, 30 minutes, or 35 minutes.

[0022] S3. Extrude the clinker into a mold, dry it, and calcine it to obtain a super acid carrier.

[0023] In one embodiment, the drying temperature is 80~120°C, and the drying time is 6~10 hours. For example, the drying temperature can be 90°C, 100°C, or 110°C. The drying time can be 7 hours, 8 hours, or 9 hours.

[0024] In one embodiment, the calcination temperature is 500-600°C, and the calcination time is 6-10 hours. For example, the calcination temperature can be 520°C, 550°C, or 580°C. The calcination time can be 7 hours, 8 hours, or 9 hours.

[0025] In one embodiment, the specific surface area of ​​the superacid carrier is 200-240 m². 2 / g, with a strength of 160~170 N / cm. The superacid support of the present invention has the characteristics of support stability, strong acidity, and large specific surface area, which can improve the activity and selectivity of the catalyst and increase the yield of isomerization products.

[0026] S4. The superacid support and the metal compound solution are placed in a reaction vessel and subjected to pressure, depressurization, drying and calcination to obtain the isomerization catalyst.

[0027] In one embodiment, the solution of the metal compound comprises the metal compound and water, and the metal compound includes one or more of the following: metal halide, metal sulfate, metal nitrate, metal acetate, and metal oxalate. Further, the metal in the metal compound includes one or more of platinum, palladium, barium, yttrium, and lanthanum. For example, when the metal in the metal compound includes platinum, palladium, barium, yttrium, and lanthanum, the mass ratio of the platinum compound, palladium compound, barium compound, yttrium compound, lanthanum compound, and water is 40~44:15~20:55~60:300~320:550~570:5500~6500, for example, 42:17:57:309:561:6000 or 43:19:58:312:565:6100.

[0028] In one embodiment, the mass ratio of the superacid carrier, the metal compound, and water is 8-10:1:5-7. For example, the mass ratio of the superacid carrier, the metal compound, and water can be 9:1:5 or 9.5:1:6.5.

[0029] In one embodiment, the pressure is increased to 0.5–3 MPa and maintained for 2–6 hours before depressurization. For example, the pressure is increased to 1 MPa, 2.4 MPa, and 2.6 MPa, and maintained for 3 hours, 4 hours, and 5 hours before depressurization. Further, during the pressurization process, the stirrer of the reactor stirs the superacid support and the metal compound solution at a speed of 8–12 r / min. For example, the stirring speed is 9 r / min or 10 r / min.

[0030] In one embodiment, drying includes vacuum drying and heating drying, with the heating temperature at 70-90°C and the heating time at 4-8 hours. For example, the heating temperature can be 75°C, 80°C, or 85°C. The heating time can be 5 hours, 8 hours, or 9 hours.

[0031] In one embodiment, the calcination temperature is 500~700℃, and the calcination time is 6~10h. For example, the calcination temperature can be 520℃, 550℃, or 650℃. The calcination time can be 7h, 8h, or 9h.

[0032] This invention optimizes the acidic site distribution of a superacid support by introducing a high-pressure impregnation method, achieving efficient, stable, and environmentally friendly catalyst preparation. This superacid support is suitable for high surface area and porous materials such as zirconium oxide, alumina, or silicon-aluminum composites. Furthermore, the high-pressure impregnation method can specifically solve the problem of uneven solution distribution caused by surface tension or capillary action in traditional impregnation methods. Specifically, by applying external pressure, the active material is forced to penetrate deeper and more uniformly into the pore structure of the support, thereby significantly improving the uniformity of the distribution of effective components in the catalyst.

[0033] Secondly, the present invention provides an isomerization catalyst, which is obtained by the above-described method for preparing isomerization catalysts. The specific surface area of ​​the isomerization catalyst of the present invention is 216~235 m². 2 / g, strength is 150~170 N / cm, C5 isomerization rate is 40%~60%, C6 isomerization rate is 40%~60%.

[0034] Thirdly, the present invention provides an application of an isomerization catalyst in alkane isomerization reactions.

[0035] The parameters for the alkane isomerization reaction include: a fixed-bed reactor, a reaction pressure of 1–4 MPa, a temperature of 160–200 °C, and a mass hourly space velocity of 1–3 h⁻¹. -1 The hydrogen-to-oil molar ratio is 1.0 to 3.0. By weight percentage, the raw material composition includes: n-pentane: 30%, isohexane: 40%, isopentane: 21%, and n-hexane: 9%.

[0036] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0037] The present invention will be described in detail below through embodiments and experimental examples. However, these are merely examples and do not limit the present invention in any way.

[0038] Example 1 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Carrier preparation: 700g of ZrO2-SO4 2- The powder, 50g of phosphomolybdic tungsten heteropoly acid, and 100g of pseudoboehmite were sequentially added to a kneader for 20-50 minutes. Then, 180g of a 30% nitric acid aqueous solution was added, and kneading continued for 20-40 minutes. The kneaded material was then extruded through an extruder. The extruded strip carrier was dried at 100℃ for 8 hours, and then calcined at 550℃ for 8 hours to obtain superacid carrier 1 with a specific surface area of ​​240 m². 2 / g, strength 165 N / cm.

[0039] Catalyst preparation: 964g of support was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor, pressurized to 2MPa, and maintained for 4 hours before depressurization. During the reaction, the reactor was continuously stirred at 10r / min. Then, excess water was evaporated under vacuum. After the surface of the support was dried, it was removed and dried at 80℃ for 6 hours, and then calcined at 600℃ for 8 hours to obtain catalyst A.

[0040] Example 2 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Catalyst preparation: 964g of superacid support 1 was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor, pressurized to 1MPa, and maintained for 4 hours before depressurization. During the reaction, the reactor was continuously stirred at 10r / min. Then, excess water was evaporated under vacuum. After the surface of the support was dried, it was removed and dried at 80℃ for 6 hours, and then calcined at 600℃ for 8 hours to obtain catalyst B.

[0041] Example 3 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Catalyst preparation: 964g of superacid support 1 was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor, pressurized to 0.5 MPa, and maintained for 4 hours before depressurization. During the reaction, the reactor was continuously stirred at 10 r / min. Then, excess water was evaporated under vacuum. After the surface of the support was dried, it was removed and dried at 80℃ for 6 hours, and then calcined at 600℃ for 8 hours to obtain catalyst C.

[0042] Example 4 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Catalyst preparation: 964g of superacid support 1 was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor, pressurized to 1MPa, and maintained for 6 hours before depressurization. During the reaction, the reactor was continuously stirred at 10r / min. Then, excess water was evaporated under vacuum. After the surface of the support was dried, it was removed and dried at 80℃ for 6 hours, and then calcined at 600℃ for 8 hours to obtain catalyst D.

[0043] Example 5 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Catalyst preparation: 964g of superacid support 1 was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor, pressurized to 1MPa, and maintained for 2 hours before depressurization. During the reaction, the reactor was continuously stirred at 10r / min. Then, excess water was evaporated under vacuum. After the surface of the support was dried, it was removed and dried at 80℃ for 6 hours, and then calcined at 600℃ for 8 hours to obtain catalyst E.

[0044] Comparative Example 1 This embodiment provides a method for preparing an isomerization catalyst, including the following steps: Catalyst preparation: 964g of superacid support 1 was placed in a high-pressure reactor. Then, 4.2g of chloroplatinic acid, 1.7g of palladium dichloride, 5.7g of barium nitrate, 30.9g of yttrium nitrate, and 56.1g of lanthanum nitrate were dissolved in 600g of water to prepare a solution. The solution was added to the reactor and kept under normal pressure. During the reaction, the reactor was continuously stirred at 10 r / min. Then, the excess water was evaporated under vacuum. After the surface of the support was dried, it was taken out and dried at 80℃ for 6 hours and calcined at 600℃ for 8 hours to obtain catalyst F.

[0045] Test case The isomerization catalysts obtained in the examples and comparative examples were used in a fixed-bed reactor at a reaction pressure of 2.5 MPa, a temperature of 180 °C, and a mass hourly space velocity of 1.5 h⁻¹. -1 Hydrogen-to-oil molar ratio: 2.0. Raw material composition: isopentane: 21%, n-pentane: 30%, n-hexane: 9%, isohexane: 40%.

[0046] The physicochemical properties of the catalyst are shown in Table 1, and the test data of the isomerization properties of the catalyst are shown in Table 2.

[0047] Table 1 Table 2 This invention successfully optimized the preparation process of superacid isomerization supports by introducing a high-pressure impregnation method, achieving uniform distribution of acidic sites and stability of noble metal loading. Test results show that, under the same reaction conditions, the catalyst prepared by high-pressure impregnation (such as catalyst B, at 1 MPa and 4 h) exhibits the best performance, with a C5 isomerization rate of 58.2% and a C6 isomerization rate of 59.3%, significantly better than catalyst F prepared under atmospheric pressure (43.6% and 42.3%, respectively). This method not only improves the activity and selectivity of the catalyst but also reduces energy consumption and environmental risks, aligning with the development trend of green chemistry. In the future, this technology can be further extended to other alkane isomerization fields, possessing broad industrial application prospects and economic value.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an isomerization catalyst, characterized in that, The method includes: S1, ZrO2-SO4 2- The mixture is obtained by kneading phosphomolybdenum tungsten heteropoly acid and pseudoboehmite. S2. Knead the mixture with the nitric acid aqueous solution to obtain the clinker; S3. Extrude the clinker into a mold, dry it, and calcine it to obtain a super acid carrier; S4. The superacid support and the metal compound solution are placed in a reaction vessel and subjected to pressure, depressurization, drying and calcination to obtain the isomerization catalyst; wherein, the metal compound solution includes metal compound and water, and the metal compound includes one or more of metal halide, metal sulfate, metal nitrate, metal acetate and metal oxalate.

2. The preparation method according to claim 1, characterized in that, The ZrO2-SO4 2- The mass ratio of phosphomolybdic tungsten heteropoly acid, pseudoboehmite, and nitric acid aqueous solution is 60~80:40~60:5~10:16~20; The concentration of the nitric acid aqueous solution is 10% to 50%.

3. The preparation method according to claim 1, characterized in that, In step S1, the kneading time is 20-50 minutes; In step S2, the kneading time is 20-40 minutes.

4. The preparation method according to claim 1, characterized in that, In step S3, the drying temperature is 80~120℃ and the drying time is 6~10h; The roasting temperature is 500~600℃, and the roasting time is 6~10h.

5. The preparation method according to claim 1, characterized in that, The specific surface area of ​​the superacid carrier is 200~240 m². 2 / g, with a strength of 160~170 N / cm.

6. The preparation method according to claim 1, characterized in that, The metal in the metal compound includes one or more of platinum, palladium, barium, yttrium, and lanthanum.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the superacid carrier, metal compound and water is 8~10:1:5~7.

8. The preparation method according to claim 1, characterized in that, In step S4, the pressure is increased to 0.5~3MPa, maintained for 2~6 hours, and then the pressure is released. During the pressurization process, the stirrer of the reactor stirs the superacid carrier and the metal compound solution at a speed of 8~12 r / min. The drying process includes vacuum drying and heating drying, with the heating temperature being 70~90℃ and the heating time being 4~8 hours; The roasting temperature is 500~700℃, and the roasting time is 6~10h.

9. An isomerization catalyst, characterized in that, The isomerization catalyst is obtained by the preparation method of the isomerization catalyst according to any one of claims 1 to 8.

10. The application of the isomerization catalyst according to claim 9 in the alkane isomerization reaction.

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