Multiple acid modified long-chain isomerization catalyst and preparation method thereof

Abstract

The invention provides a multi-acid modified long-chain isomerization catalyst and a preparation method thereof. The preparation method comprises the following steps: dipping tetragonal zirconium oxide by adopting a combination of two or three of a solution containing sulfate radicals, a solution containing phosphotungstate radicals and an ammonia water solution containing molybdate radicals, performing first drying and first roasting, and then compounding the tetragonal zirconium oxide with a ZSM-48 molecular sieve according to a mass ratio of 5: 95-95: 5 to obtain a composite carrier; impregnating the composite carrier with platinum, and performing secondary drying, secondary roasting and reduction to obtain the multi-acid modified long-chain isomerization catalyst. According to different requirements of the long-chain alkane isomerization catalyst, the acid strength, the particle size and the specific surface property of the catalyst can be adjusted by adopting different solutions and the ratio of the nanoscale tetragonal zirconium oxide to the ZSM-48.

Description

Technical Field

[0001] This invention relates to a long-chain isomerization catalyst modified with multiple acids and its preparation method, belonging to the field of catalyst preparation technology. Background Technology

[0002] For a long time, aviation fuel has been an indispensable power source in people's daily lives and production. Its main source is fossil fuels, generally produced through petroleum refining. Due to the non-renewable nature of fossil resources, the long-term and large-scale use of fossil fuels to produce liquid fuels will gradually deplete these precious non-renewable resources. Furthermore, the oil refining process is primarily a high-temperature, high-pressure process, consuming extremely high amounts of energy and generating large quantities of greenhouse gases, polluting the environment. Liquid fuels prepared from renewable animal and vegetable oils through deoxygenation have significant advantages, including renewable raw materials, high calorific value, good combustion performance, similar composition to fossil fuels, and good compatibility. They are of great importance to the sustainable supply of liquid fuels and have received widespread attention and importance both domestically and internationally. Therefore, researchers in the industry are increasingly focusing on the research, development, and industrial application of technologies for preparing liquid fuels from low-quality oils.

[0003] Currently, the main processes for producing liquid fuels using inferior oils include oil methylation, hydrogenation, dehydration, and hydroisomerization. Hydroisomerization, in particular, uses long-chain alkanes as raw materials and, under specific temperature, pressure, hydrogen-to-oil ratio, and catalyst conditions, converts straight-chain alkanes into low-pour-point isoalkanes. Alternatively, oils can be used as raw materials for hydrogenation and deoxygenation in the presence of a catalyst to convert them into long-chain alkanes, followed by isomerization under specific process conditions and catalyst presence. By adjusting the catalyst composition and isomerization conditions, gasoline, diesel, or aviation kerosene can be selectively produced. Canmet has developed a technology for producing diesel from oils through hydrogenation, resulting in a product with a high cetane number. Neste Oil and UOP have also successfully developed technologies for producing diesel from oils through catalytic hydrogenation and deoxygenation, as well as for producing aviation kerosene from biomass feedstocks.

[0004] CN116333782A discloses a method for selectively hydrogenating and deoxygenating oils to prepare liquid fuels. This method uses animal and vegetable oils as raw materials and prepares liquid fuels through steps such as oil methylation, hydrogenation, dehydration, and hydroisomerization. This method has certain economic and safety advantages, but it still suffers from low selectivity and yield of isomerization products during the isomerization of long-chain alkanes.

[0005] CN116333823A provides a method for selectively hydrodeoxygenating oils to prepare liquid fuels. The long-chain alkane isomerization catalyst used in this method is one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, EU-1, Y molecular sieve, and β molecular sieve. The catalyst of this method has certain long-chain alkane isomerization activity and selectivity. However, the long-chain alkane isomerization process inevitably involves reactions such as cracking, cyclization, and superposition, which leads to a decrease in the selectivity and yield of the target product of the long-chain alkane isomerization reaction.

[0006] The properties of the support, such as acidity and pore structure, average pore size, and the range and proportion of pore sizes where the pore distribution is mainly concentrated, play a crucial role in the activity, selectivity, stability, and regeneration performance of the catalyst used. Therefore, the support must possess certain acidity and pore structure to ensure the selectivity and stability of the catalyst. To further improve the selectivity and yield of target products in the isomerization process of long-chain alkanes, and to provide an efficient method for producing liquid fuels from low-quality oils, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a long-chain isomerization catalyst modified with multiple acids and its preparation method. This catalyst exhibits good activity stability, high selectivity for the target product, and high yield.

[0008] To achieve the above objectives, the present invention provides a method for preparing a long-chain isomerization catalyst modified with multiple acids, comprising the following steps:

[0009] Tetragonal zirconium oxide was impregnated with two or three of the following solutions: a solution containing sulfate, a solution containing phosphotungstic acid, and an ammonia solution containing molybdate. After a first drying and a first calcination, it was compounded with ZSM-48 molecular sieve at a mass ratio of 5:95-95:5 to obtain a composite carrier.

[0010] The composite support is impregnated with platinum, and then dried and calcined a second time to obtain the long-chain isomerized catalyst modified with multiple acids;

[0011] Wherein, based on the dry basis mass of the tetragonal zirconium oxide as 100%, the loadings of sulfur, phosphorus, and molybdenum are 0.1-3% respectively;

[0012] Wherein, based on the dry basis mass of the composite carrier as 100%, the platinum loading is 0.1-1%.

[0013] In the above preparation method, the catalyst obtained by impregnating and modifying tetragonal zirconium oxide with a solution containing sulfate, a solution containing phosphotungsten, and an ammonia solution containing molybdate can be used for long-chain alkane isomerization reactions, and can obtain high cetane numbers and liquid yields. This indicates that the catalyst prepared by the present invention has high activity stability, product selectivity, and yield. Moreover, the present invention has found that the catalyst provided by the present invention can also obtain a low freezing point. When using two solutions for modification, a combination of a solution containing sulfate and a solution containing phosphotungsten, or a combination of a solution containing sulfate and an ammonia solution containing molybdate is preferred.

[0014] In the above preparation method, the loading of sulfate, phosphotungstic acid, and molybdate is calculated based on the mass of sulfur, phosphorus, and molybdenum, respectively, and the loading of platinum is calculated based on the mass of platinum.

[0015] In the above preparation method, preferably, the particle size of the tetragonal zirconium oxide is 5-20 nm.

[0016] In the above preparation method, preferably, the tetragonal zirconium oxide is prepared by the following steps:

[0017] Adjust the pH of the zirconium salt solution to 7-10 and stir thoroughly to obtain a homogeneous zirconium hydroxide.

[0018] The zirconium hydroxide was filtered, washed, dried, and calcined to obtain tetragonal zirconium oxide.

[0019] According to a specific embodiment of the present invention, a preferred preparation method is to obtain zirconium oxide by co-precipitation. Suitable zirconium salts include zirconium oxychloride, zirconium sulfate, zirconium oxynitrate, etc., preferably zirconium oxychloride and / or zirconium oxynitrate.

[0020] According to a specific embodiment of the present invention, the pH adjuster can be ammonia, etc.

[0021] According to a specific embodiment of the present invention, in the process of preparing tetragonal zirconium oxide, the calcination temperature is 470-600℃ and the time is 6-12 hours.

[0022] According to a specific embodiment of the present invention, preferably, the preparation process of tetragonal zirconium oxide includes the following specific steps:

[0023] After adjusting the pH of the above solution to 7-10 with ammonia or similar solution, the solution was stirred vigorously to obtain a homogeneous zirconium hydroxide. After thorough stirring and reaction for a certain period, the solution was repeatedly washed using a Buchner funnel to remove impurities (NO3). 2- and Cl -After washing, the material is dried and calcined at 50-150℃ using conventional methods to transform it into nanoscale tetragonal zirconia carriers with a particle size of 5-20nm.

[0024] In the above preparation method, preferably, the sulfate concentration of the sulfate-containing solution is 0.1-5 mol / L.

[0025] In the above preparation method, preferably, the concentration of phosphotungsten ion in the solution containing phosphotungsten ion is 0.1-5 mol / L.

[0026] In the above preparation method, preferably, the molybdate concentration of the ammonia solution containing molybdate is 0.1-5 mol / L.

[0027] In the above preparation method, preferably, the solution containing sulfate ions includes one or more of sulfuric acid, ammonium sulfate aqueous solution, and ammonium bisulfate aqueous solution.

[0028] In the above preparation method, preferably, the solution containing phosphotungstate includes one or more of phosphotungstic acid, aqueous solution of ammonium phosphate, and aqueous solution of diammonium hydrogen phosphate.

[0029] In the above preparation method, preferably, the ammonia solution containing molybdate includes one or a combination of two of the following: an ammonia solution of molybdic acid and an ammonia solution of ammonium molybdate.

[0030] In the above preparation method, preferably, the impregnation solution used for impregnating platinum includes one or more of chloroplatinic acid, ammonium chloroplatinate aqueous solution, and platinum acetylacetonate aqueous solution.

[0031] According to a specific embodiment of the present invention, preferably, the mass ratio is 30:70-72:28. This mass ratio refers to the mass ratio of tetragonal zirconium oxide to ZSM-48 molecular sieve after impregnation, first drying, and first calcination.

[0032] According to a specific embodiment of the present invention, preferably, the platinum loading is 0.2-0.3% based on 100% dry weight of the composite carrier, more preferably 0.23-0.27%.

[0033] According to a specific embodiment of the present invention, preferably, the preparation method of the long-chain alkane isomerization catalyst of the present invention includes the following specific steps:

[0034] (1) Adjust the pH of the zirconium salt solution to 7-10 using ammonia water, and stir thoroughly for 0.5-5 hours to obtain zirconium hydroxide;

[0035] (2) The zirconium hydroxide is washed and filtered (using a Buchner funnel to remove impurities such as chloride ions and nitrate ions), and then dried at 50-150℃ (using a forced-air drying oven) to obtain nanoscale tetragonal zirconium oxide carriers with a particle size of 5-20nm.

[0036] (3) The nano-sized tetragonal zirconia support is stirred and impregnated with a solution of sulfate concentration of 0.1-5 mol / L for 0.5-10 hours, and the impregnated product is filtered and washed. In this step, the sulfate-containing solution is stirred and impregnated to ensure that the sulfate is fully loaded on the nano-sized tetragonal zirconia support. The unloaded sulfate is washed away and the solution is allowed to evaporate and dry. The sulfate content in the solution should reach the sulfur content required for the catalyst.

[0037] (4) Stir and impregnate with a solution containing 0.1-5 mol / L of phosphotungsten ions for 0.5-10 hours, and then filter and wash the impregnated product. In this step, stir and impregnate with a solution containing phosphotungsten ions to ensure that the phosphotungsten ions are fully loaded onto the nano-scale tetragonal zirconium oxide support, wash away the unloaded phosphotungsten ions, and allow the solution to evaporate and dry. The phosphotungsten ion content in the solution should reach the tungsten content required for the catalyst.

[0038] (5) Then, stir and impregnate with an ammonia solution with a molybdate concentration of 0.1-5 mol / L for 0.5-10 hours, and filter and wash the impregnated product; in this step, stir and impregnate with an ammonia solution containing molybdate to fully load the molybdate onto the nano-scale tetragonal zirconia support, wash away the unloaded molybdate, and allow the solution to evaporate and dry; the molybdate content in the solution should reach the molybdenum content required by the catalyst;

[0039] (6) Dry the filtered, washed and impregnated product at 50-150℃ (first drying);

[0040] (7) The dried product was calcined at 350-750℃ (first calcination) for 2-4 hours to obtain nano-sized tetragonal zirconium oxide containing sulfate, phosphotungstic acid and molybdate.

[0041] (8) Mix the calcined nano-scale tetragonal zirconium oxide from step (7) with ZSM-48 molecular sieve and form it to obtain a molded carrier; during the molding process, binders, pore expanders and extrusion aids can be added, and it can be extruded into strips or other shapes.

[0042] (9) Prepare a platinum-containing impregnation solution to impregnate the molded support (use a platinum-containing impregnation solution prepared in a predetermined amount, such as chloroplatinic acid solution, to impregnate the support, the platinum content should reach the platinum content required for the catalyst, the impregnation time is 0.5-10 hours), and then dry (second drying), calcinate at 450-700℃ (second calcination) for 2-4 hours, and reduce with hydrogen at 350-550℃ for 4-12 hours to obtain a long-chain isomerization catalyst modified with multiple acids.

[0043] The present invention also provides a long-chain isomerization catalyst modified by multiple acids, which is prepared by the above method.

[0044] The preparation method of this invention uses nanoscale tetragonal zirconium oxide with a particle size of 5-20 nm as a support. Compared with monoclinic zirconium oxide, the tetragonal structure is more sensitive to defects. Its crystal structure contains planes and directions that are relatively easy to form predefined defects, making it more prone to defects. As a catalyst support, it easily forms more active sites. Impregnation with multiple acids (two or three combinations of sulfate, phosphotungsten, and molybdate) and then using it as a catalyst support can improve the acid strength of the catalyst, preparing a solid superacid with suitable acidity (while monoclinic zirconium oxide did not show similar results). This is then combined with ZSM-48 molecular sieves to obtain a composite support with flexibly adjustable acidity, which is then impregnated with platinum to prepare a long-chain alkane isomerization catalyst. The tetragonal zirconium oxide support loaded with sulfate, phosphotungsten, and molybdate can provide more isomerization reaction sites. After mixing with ZSM-48, a composite support is obtained. The catalyst prepared using this composite support has good activity stability, high selectivity for the target product, and high yield. Catalyst evaluation revealed that the overall performance of the catalyst is superior to that of commonly used Pt / ZSM-48 and Pt / ZSM-22 catalysts.

[0045] The preparation method of the present invention can adjust the acid strength, particle size and specific surface area of ​​the catalyst by using different solutions and the ratio of nano-sized tetragonal zirconium oxide to ZSM-48 according to different requirements of long-chain alkane isomerization catalysts. Attached Figure Description

[0046] Figure 1 Electron micrograph of nanoscale tetragonal zirconium oxide.

[0047] Figure 2 XRD of nanoscale tetragonal zirconium oxide. Detailed Implementation

[0048] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0049] Example 1

[0050] This embodiment provides a long-chain isomerization catalyst modified with multiple acids, which is prepared through the following steps:

[0051] (1) Preparation of nanoscale tetragonal zirconium oxide support

[0052] Zirconium oxychloride was dissolved in deionized water (zirconium concentration 0.4 mol / L). While stirring, 10% ammonia solution was added dropwise to adjust the pH to 8. The reaction was allowed to proceed for 2 hours. Afterwards, the solution was filtered and washed using a Buchner funnel, dried at 110℃ for 24 hours, and calcined at 515℃ for 6 hours to obtain nanoscale tetragonal zirconium oxide support. Figure 1 Electron micrograph of a nanoscale tetragonal zirconium oxide support. Figure 2 XRD pattern of nanoscale tetragonal zirconia with a particle size of 9 nm.

[0053] (2) Multiple acid impregnation and carrier composite

[0054] The nano-sized tetragonal zirconium oxide support obtained in step (1) was prepared with a predetermined amount of dilute sulfuric acid impregnation solution. The sulfate content in the impregnation solution should reach the sulfur content required by the catalyst. After impregnation for 1 hour by equal volume, it was dried at 120°C for 4 hours. Then, a predetermined amount of dilute phosphotungstic acid impregnation solution was prepared. The phosphotungstic acid content in the impregnation solution should reach the tungsten content required by the catalyst. After impregnation for 1 hour by equal volume, it was dried at 120°C for 4 hours. Then, a predetermined amount of dilute molybdate impregnation solution was prepared. The molybdate content in the impregnation solution should reach the molybdenum content required by the catalyst. After impregnation for 1 hour by equal volume, it was dried at 120°C for 4 hours. After that, it was calcined at 650°C for 3 hours. It was then compounded with ZSM-48 molecular sieve at a mass ratio of 30:70 and extruded into strips or other shapes to obtain a nano-sized tetragonal zirconium oxide composite support containing sulfate, phosphotungstic acid and molybdate.

[0055] Specifically, based on the dry basis mass of the tetragonal zirconium oxide as 100%, the loadings of sulfur, phosphorus, and molybdenum are 1.8%, 1.5%, and 0.5%, respectively.

[0056] (3) Impregnation with platinum

[0057] Prepare a chloroplatinic acid impregnation solution with a platinum content of 0.23% (w), impregnate the composite support obtained in step (2) in the impregnation solution, stir and impregnate for 1 hour, wash off the unloaded platinum, dry at 110°C for 24 hours, calcine at 550°C for 3 hours, and reduce at 450°C for 6 hours under hydrogen to obtain catalyst A.

[0058] Example 2

[0059] This embodiment provides a long-chain isomerization catalyst modified with multiple acids, which is prepared through the following steps:

[0060] (1) Preparation of nanoscale tetragonal zirconium oxide support

[0061] Zirconium oxychloride was dissolved in deionized water (zirconium concentration was 0.4 mol / L), and 15% ammonia was added dropwise while stirring to adjust the pH to 8.5. The reaction was carried out for 4 hours. After that, the solution was filtered and washed with a Buchner funnel, dried at 110℃ for 24 hours, and calcined at 480℃ for 7 hours to obtain a nano-sized tetragonal zirconia support with a particle size of 12 nm.

[0062] (2) Multiple acid impregnation and carrier composite

[0063] The nano-sized tetragonal zirconium oxide support obtained in step (1) was prepared with a mixed impregnation solution of ammonium sulfate and sulfuric acid in a predetermined amount. The sulfur content in the impregnation solution should reach the sulfur content required by the catalyst. After impregnation for 3 hours, it was dried at 120°C for 4 hours. Then, a dilute ammonia molybdate impregnation solution was prepared in a predetermined amount. After impregnation for 3 hours, it was dried at 120°C for 4 hours. After that, it was calcined at 550°C for 4 hours. It was then compounded with ZSM-48 molecular sieve at a mass ratio of 47:53 and extruded into strips or other shapes to obtain a nano-sized tetragonal zirconium oxide and ZSM-48 composite support containing sulfate and molybdate.

[0064] Specifically, based on a dry basis of 100% of the tetragonal zirconium oxide, the loadings of sulfur and molybdenum are 1.0% and 2.5%, respectively.

[0065] (3) Impregnation with platinum

[0066] Prepare an ammonium chloroplatinate impregnation solution with a platinum content of 0.25% (w), impregnate the composite carrier obtained in step (2) in the impregnation solution, impregnate for 2 hours with equal volume, dry at 120°C for 24 hours, calcine at 550°C for 4 hours, and reduce at 495°C for 4 hours under hydrogen to obtain catalyst B.

[0067] Example 3

[0068] This embodiment provides a long-chain isomerization catalyst modified with multiple acids, which is prepared through the following steps:

[0069] (1) Preparation of nanoscale tetragonal zirconium oxide support

[0070] Zirconium oxychloride was dissolved in deionized water (zirconium concentration was 0.6 mol / L), and 25% ammonia was added dropwise while stirring to adjust the pH to 9. The reaction was carried out for 4 hours. After that, the solution was filtered and washed with a Buchner funnel, dried at 110℃ for 24 hours, and calcined at 470℃ for 12 hours to obtain a nano-sized tetragonal zirconia support with a particle size of 15 nm.

[0071] (2) Multiple acid impregnation and carrier composite

[0072] The nano-scale tetragonal zirconium oxide support obtained in step (1) is prepared with a mixed impregnation solution of ammonium bisulfate and sulfuric acid in a predetermined amount. The sulfur content in the impregnation solution should reach the sulfur content required by the catalyst. After impregnation for 3 hours, it is dried at 120°C for 4 hours. Then, a phosphotungstic acid, ammonium phosphate and diammonium hydrogen phosphate impregnation solution is prepared in a predetermined amount. After impregnation for 3 hours, it is dried at 120°C for 4 hours. Then, it is calcined at 550°C for 4 hours. After being compounded with ZSM-48 molecular sieve at a mass ratio of 72:28, it is extruded into strips or other shapes to obtain a nano-scale tetragonal zirconium oxide and ZSM-48 composite support containing sulfate and phosphate.

[0073] Specifically, based on a dry basis of 100% of the tetragonal zirconium oxide, the loadings of sulfur and phosphorus are 2.0% and 1.1%, respectively.

[0074] (3) Impregnation with platinum

[0075] Prepare a chloroplatinic acid impregnation solution with a platinum content of 0.27% (w), impregnate the composite support obtained in step (2) in the impregnation solution, impregnate for 4 hours with equal volume, dry at 120°C for 12 hours, calcine at 600°C for 6 hours, and reduce at 520°C for 4 hours under hydrogen to obtain the chemical catalyst C.

[0076] Example 4

[0077] This embodiment provides a long-chain isomerization catalyst modified with multiple acids, which is prepared through the following steps:

[0078] (1) Preparation of nanoscale tetragonal zirconium oxide support

[0079] Zirconium oxychloride was dissolved in deionized water (zirconium concentration was 0.5 mol / L), and 20% ammonia was added dropwise while stirring to adjust the pH to 8. The reaction was carried out for 5 hours. After that, the solution was filtered and washed with a Buchner funnel, dried at 110℃ for 24 hours, and calcined at 600℃ for 10 hours to obtain a nano-sized tetragonal zirconia support with a particle size of 16 nm.

[0080] (2) Multiple acid impregnation and carrier composite

[0081] The nano-scale tetragonal zirconium oxide support obtained in step (1) was prepared with a predetermined amount of dilute sulfuric acid impregnation solution. The sulfate content in the impregnation solution should reach the sulfur content required by the catalyst. After impregnation for 2 hours, it was dried at 120°C for 4 hours. Then, a predetermined amount of dilute phosphotungstic acid impregnation solution was prepared. The phosphotungstic acid content in the impregnation solution should reach the tungsten content required by the catalyst. After impregnation for 2 hours, it was dried at 120°C for 4 hours. Then, a predetermined amount of ammonia water impregnation solution of ammonium molybdate was prepared. The molybdate content in the impregnation solution should reach the molybdenum content required by the catalyst. After impregnation for 2 hours, it was dried at 120°C for 4 hours. After that, it was calcined at 650°C for 3 hours. After being compounded with ZSM-48 molecular sieve at a mass ratio of 55:45, it was extruded into strips or other shapes to obtain a nano-scale tetragonal zirconium oxide composite support containing sulfate, phosphotungstic acid and molybdate.

[0082] Specifically, based on the dry basis mass of the tetragonal zirconium oxide as 100%, the loadings of sulfur, phosphorus, and molybdenum are 1.3%, 1.9%, and 1.7%, respectively.

[0083] (3) Impregnation with platinum

[0084] Prepare a platinum acetylacetone impregnation solution with a platinum content of 0.26% (w), impregnate the composite support obtained in step (2) in the impregnation solution, impregnate for 1 hour with an equal volume, dry at 110°C for 24 hours, calcine at 575°C for 3 hours, and reduce at 600°C for 7 hours under hydrogen to obtain catalyst D.

[0085] Comparative Example 1

[0086] A long-chain alkane isomerization catalyst E on a ZSM-48 and ZSM-22 composite support was prepared using the method described in CN116333823A. Specifically, in Example 1, the composite support was prepared by ZSM-48 and ZSM-22 in a mass ratio of 1:1.

[0087] Evaluation Test

[0088] Long-chain alkane isomerization reaction experiments were conducted using the catalysts provided in the examples and comparative examples in a small fixed-bed reactor, specifically in the following manner:

[0089] A long-chain alkane isomerization catalyst was loaded into a small fixed-bed reactor at a loading volume of 10 mL. Cottonseed oil was introduced to carry out the long-chain alkane isomerization reaction at 360 °C and 4 MPa, with a feed weight hourly space velocity (WHSV) of 2.0 h⁻¹. -1 The hydrogen-to-hydrocarbon molar ratio is 4. The composition of cottonseed oil is shown in Table 1, and the evaluation results are shown in Table 2.

[0090] Table 1 Composition of cottonseed oil

[0091]

[0092] Table 2 Evaluation Results

[0093]

[0094] As can be seen from the evaluation results recorded in Table 2, the long-chain isomerization reaction of long-chain alkane modified by the multi-acid catalyst provided by the present invention can obtain a high cetane number and liquid yield, and can also obtain a freezing point below -40°C. This indicates that the catalyst provided by the present invention has high selectivity and yield of the target product.

Claims

1. A method for preparing a long-chain isomerization catalyst modified by multiple acids, comprising the following steps: Tetragonal zirconia was impregnated with equal volumes of two or three of the following solutions: a solution containing sulfate, a solution containing phosphotungstic acid, and an ammonia solution containing molybdate. After a first drying and a first calcination, it was compounded with ZSM-48 molecular sieve at a mass ratio of 5:95-95:5 to obtain a composite carrier. The composite support was impregnated with platinum, and after a second drying, a second calcination, and reduction, the multi-acid modified long-chain isomerized catalyst was obtained. Wherein, based on the dry basis mass of the tetragonal zirconium oxide as 100%, the loadings of sulfur, phosphorus, and molybdenum are 0.1-3% respectively; Wherein, based on the dry basis mass of the composite carrier as 100%, the platinum loading is 0.1-1%.

2. The preparation method according to claim 1, wherein, The particle size of the tetragonal zirconium oxide is 5-20 nm.

3. The preparation method according to claim 2, wherein, The tetragonal zirconium oxide is prepared by the following steps: Adjust the pH of the zirconium salt solution to 7-10 and stir thoroughly to obtain a homogeneous zirconium hydroxide. The zirconium hydroxide was filtered, washed, dried, and calcined to obtain tetragonal zirconium oxide.

4. The preparation method according to claim 1, wherein, The sulfate concentration of the solution containing sulfate is 0.1-5 mol / L; The concentration of phosphotungsten ion in the solution containing phosphotungsten ion is 0.1-5 mol / L; The concentration of molybdate in the ammonia solution containing molybdate is 0.1-5 mol / L.

5. The preparation method according to claim 1 or 4, wherein, The sulfate-containing solution includes one or more of sulfuric acid, ammonium sulfate aqueous solution, and ammonium bisulfate aqueous solution.

6. The preparation method according to claim 1 or 4, wherein, The solution containing phosphotungstic acid ions includes one or more of phosphotungstic acid, aqueous solution of ammonium phosphate, and aqueous solution of diammonium hydrogen phosphate.

7. The preparation method according to claim 1 or 4, wherein, The ammonia solution containing molybdate includes one or a combination of two of the following: an ammonia solution of molybdic acid and an ammonia solution of ammonium molybdate.

8. The preparation method according to claim 1, wherein, The impregnation solution used for impregnating platinum includes one or more of the following: chloroplatinic acid, ammonium chloroplatinate aqueous solution, and platinum acetylacetonate aqueous solution.

9. The preparation method according to claim 1, wherein, The mass ratio is 30:70-72:

28.

10. The preparation method according to claim 1, wherein, Based on the dry weight of the composite carrier being 100%, the platinum loading is 0.2-0.3%.

11. The preparation method according to claim 1, wherein, The preparation method includes the following specific steps: (1) Adjust the pH of the zirconium salt solution to 7-10 using ammonia water, and stir thoroughly for 0.5-5 hours to obtain zirconium hydroxide; (2) The zirconium hydroxide is washed and filtered, and then dried at 50-150℃ to obtain a nanoscale tetragonal zirconium oxide support with a particle size of 5-20nm. (3) The nano-sized tetragonal zirconium oxide support was stirred and impregnated with a solution with a sulfate concentration of 0.1-5 mol / L for 0.5-10 hours, and the impregnated product was filtered and washed. (4) Then, stir and impregnate the product with a phosphotungstic acid solution with a concentration of 0.1-5 mol / L for 0.5-10 hours, and filter and wash the impregnated product. (5) Then, stir and impregnate the product with an ammonia solution with a molybdate concentration of 0.1-5 mol / L for 0.5-10 hours, and filter and wash the impregnated product. (6) Dry the filtered, washed and impregnated product at 50-150℃. (7) The dried product was calcined at 350-750℃ for 2-4 hours to obtain nano-sized tetragonal zirconium oxide containing sulfate, phosphotungsten, and molybdate. (8) The nano-sized tetragonal zirconium oxide calcined in step (7) is mixed with ZSM-48 molecular sieve and shaped to obtain a shaped carrier; (9) Prepare a platinum-containing impregnation solution to impregnate the molded carrier, and then dry it, calcine it at 450-700℃ for 2-4 hours, and reduce it at 350-550℃ for 4-12 hours to obtain a long-chain isomerization catalyst modified by multiple acids.

12. A long-chain isomerization catalyst modified with multiple acids, which is prepared by the method according to any one of claims 1-11.

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