Catalyst and process for its preparation

Abstract

The application provides a catalyst and a preparation method thereof, and particularly relates to the technical field of propylene oligomerization. The catalyst is used in a propylene oligomerization reaction, and the catalyst is a porous silicon zirconium oxide. The specific surface area of the porous silicon zirconium oxide is not less than 260 m 2 / g. The catalyst provided by the application has the advantages that the porous silicon zirconium oxide has high specific surface area, rich mesopore distribution and uniformly dispersed doping structure. The structure significantly improves the accessibility and stability of acid centers, effectively inhibits the beta-scission side reaction and deep polymerization carbon deposition in the propylene oligomerization process, so that the propylene conversion rate is greater than or equal to 64.4%, the nonene selectivity is 45.6-55.6% under the fixed bed reaction condition, and the activity retention rate is not less than 98% after continuous operation for not less than 300 h, which shows excellent catalytic activity, target product selectivity and industrial long-period operation stability.

Description

Technical Field

[0001] This invention relates to the field of propylene oligomerization technology, and in particular to a catalyst and its preparation method. Background Technology

[0002] Propylene oligomerization is an important industrial route for producing high-value-added olefins, especially nonene, which is widely used in the synthesis of lubricant additives, nonionic surfactants, nonylphenol, and fine chemical intermediates. Currently, the mainstream propylene oligomerization catalysts in industry mainly fall into three categories: homogeneous transition metal catalysts (such as Ni, Fe, and Co-based complexes), which, despite their high activity, have not yet achieved large-scale industrial application due to difficulties in separation and recovery, severe metal loss, and poor operational safety; solid acid catalysts, including solid phosphoric acid catalysts, molecular sieve catalysts, and supported transition metal catalysts, which generally suffer from rapid deactivation due to carbon deposition, easy pore blockage, and low nonene selectivity; and novel catalytic systems, such as ionic liquid nickel complexes, which, while possessing high stability and easy separation advantages, are costly, sensitive to moisture and temperature, and difficult to scale up in engineering.

[0003] Existing propylene oligomerization catalysts still face multiple technical bottlenecks: solid acid catalysts suffer from equipment corrosion, mechanical strength degradation, and short lifespan; molecular sieve catalysts are limited by rapid deactivation caused by pore blockage, and it is difficult to achieve both high activity and high stability; and most modification methods generally result in complex preparation processes, high energy consumption, and poor batch repeatability, which significantly increases industrialization costs.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a catalyst and its preparation method, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A first aspect of the present invention provides a catalyst for use in a propylene oligomerization reaction; the catalyst is a porous silicon zirconium oxide; wherein the specific surface area of ​​the porous silicon zirconium oxide is not less than 260 m². 2 / g.

[0007] Furthermore, in the porous silicon-zirconium oxide, the molar ratio of silicon to zirconium is 1:(0.1~0.8), preferably 1:(0.2~0.7).

[0008] The second aspect of the present invention provides a method for preparing the catalyst, wherein a silicon source solution and a zirconium source solution are added to a seed slurry for reaction, followed by filtration, washing, drying and calcination to obtain the catalyst.

[0009] Furthermore, the seed slurry contains seed crystals, a pore-expanding agent, and water.

[0010] Preferably, the concentration of the seed crystals is 0.5~50 mmol / L.

[0011] Preferably, the concentration of the pore-expanding agent is 0.02~0.04 mol / L.

[0012] Furthermore, the seed crystals include molecular sieves.

[0013] Preferably, the molecular sieve includes at least one of ZSM-5, MCM-41, and SAPO-34.

[0014] Preferably, the pore-expanding agent includes at least one of CTAB (hexadecyltrimethylammonium bromide), ethylenediamine, n-butylamine, TEAB (tetraethylammonium bromide), TPAB (tetrapropylammonium bromide), and TBAB (tetrabutylammonium bromide).

[0015] Furthermore, the concentration of the silicon source solution is 1~5 mol / L.

[0016] Preferably, the silicon source solution comprises silica sol.

[0017] Preferably, the silicon source in the silicon source solution includes at least one of water glass, silica gel powder, or tetraethyl silicate.

[0018] Furthermore, the concentration of the zirconium source solution is 0.03~1.5 mol / L.

[0019] Preferably, the zirconium source in the zirconium source solution includes at least one of zirconium sulfate, zirconium nitrate, zirconium oxynitrate, zirconium chloride, or zirconium oxychloride.

[0020] Furthermore, in the reaction system, the molar ratio of silicon source, zirconium source and seed crystal is 1:(0.1~0.8):(200~2000ppm).

[0021] Preferably, the pH of the reaction is 6 to 11.

[0022] Furthermore, the preparation method involves adjusting the pH of the system by adding an acid solution or an alkaline solution.

[0023] Preferably, the acid solution comprises sulfuric acid and / or sodium bisulfate.

[0024] Preferably, the alkaline solution includes at least one of sodium hydroxide solution, ammonia water, sodium carbonate solution, and sodium bicarbonate solution.

[0025] Furthermore, the reaction temperature is 20~80℃ and the time is 2~36h.

[0026] Preferably, the drying temperature is 50~120℃ and the time is 2~8h.

[0027] Preferably, the roasting temperature is 400~600℃ and the time is 4~12h.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: The catalyst provided by this invention is a porous silicon zirconium oxide with a high specific surface area, abundant mesopore distribution, and uniformly dispersed doped structure. This structure significantly improves the accessibility and stability of acid centers, effectively suppresses β-scission side reactions and deep polymerization carbon deposition during propylene oligomerization, thereby achieving a propylene conversion rate of ≥64.4% and a nonene selectivity of 45.6~55.6% under fixed-bed reaction conditions. Moreover, the activity retention rate is >92% after 100 h of continuous operation, demonstrating excellent catalytic activity, target product selectivity, and industrial-grade long-term operational stability.

[0029] The preparation method provided by this invention realizes in-situ co-deposition and interfacial condensation of silicon-zirconium precursors on the seed surface in an aqueous system. The entire process requires only one pot of co-precipitation. The precursors can be separated and then conventionally dried and calcined to obtain a porous catalyst with uniform structure and highly dispersed zirconium-silicon. This eliminates redundant steps, significantly shortens the preparation cycle, and has excellent process robustness, scalability, and industrialization cost advantages. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 The graph shows the changes in propylene conversion and nonene selectivity over time obtained from Example 2. Figure 2 The TG-DTA spectrum obtained in test example 2. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0033] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0034] A first aspect of the present invention provides a catalyst for use in a propylene oligomerization reaction; the catalyst is a porous silicon zirconium oxide; wherein the specific surface area of ​​the porous silicon zirconium oxide is not less than 260 m². 2 / g.

[0035] The catalyst provided by this invention is a porous silicon zirconium oxide with a high specific surface area, abundant mesopore distribution, and uniformly dispersed doped structure. This structure significantly improves the accessibility and stability of acid centers, effectively suppresses β-scission side reactions and deep polymerization carbon deposition during propylene oligomerization, thereby achieving a propylene conversion rate of ≥64.4% and a nonene selectivity of 45.6~55.6% under fixed-bed reaction conditions. Moreover, the activity retention rate is >92% after 100 h of continuous operation, demonstrating excellent catalytic activity, target product selectivity, and industrial-grade long-term operational stability.

[0036] Furthermore, in the porous silicon-zirconium oxide, the molar ratio of silicon to zirconium is 1:(0.1~0.8), preferably 1:(0.2~0.7). Too low a zirconium content leads to insufficient acid center density and uneven distribution of Lewis / Brønsted acid sites, weakening the ability to directionally regulate propylene adsorption activation and carbocation chain growth. A suitable zirconium content can form Zr-O-Si bonds, improving structural stability, inhibiting high-temperature sintering, and contributing to an increase in specific surface area. Conversely, too high a zirconium content easily induces zirconium oxide agglomeration, destroying the integrity of the mesoporous framework, reducing specific surface area and pore connectivity, and masking the thermal / hydrothermal stability support provided by the silicon-oxygen network.

[0037] Typically, but not limitingly, in the porous silicon-zirconium oxide, the molar ratio of silicon to zirconium can be, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, or 1:0.8, or any value within the range of 1:(0.1 to 0.8); preferably 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, or 1:0.7, or any value within the range of 1:(0.2 to 0.7).

[0038] The second aspect of the present invention provides a method for preparing the catalyst, wherein a silicon source solution and a zirconium source solution are added to a seed slurry for reaction, followed by filtration, washing, drying and calcination to obtain the catalyst.

[0039] The preparation method provided by this invention realizes in-situ co-deposition and interfacial condensation of silicon-zirconium precursors on the seed surface in an aqueous system. The entire process requires only one pot of co-precipitation. The precursors can be separated and then conventionally dried and calcined to obtain a porous catalyst with uniform structure and highly dispersed zirconium-silicon. This eliminates redundant steps, significantly shortens the preparation cycle, and has excellent process robustness, scalability, and industrialization cost advantages.

[0040] Furthermore, the seed slurry contains seed crystals, a pore-expanding agent, and water.

[0041] Preferably, the concentration of the seed crystals is 0.5~50 mmol / L.

[0042] Preferably, the concentration of the pore-expanding agent is 0.02~0.06 mol / L.

[0043] Furthermore, the seed crystal includes a molecular sieve. The molecular sieve of the present invention has a regular microporous / mesoporous structure, high specific surface area and abundant silanol and aluminol hydroxyl groups on its surface. It can serve as an efficient structural template and nucleation anchor point, guiding the zirconium source and silicon source precursor to undergo directional adsorption, in-situ co-deposition and interfacial condensation on its surface, significantly improving the spatial dispersion uniformity of the zirconium-silicon component.

[0044] Preferably, the molecular sieve includes at least one of ZSM-5, MCM-41, and SAPO-34.

[0045] Preferably, the pore-expanding agent includes at least one of CTAB (hexadecyltrimethylammonium bromide), ethylenediamine, n-butylamine, TEAB (tetraethylammonium bromide), TPAB (tetrapropylammonium bromide), and TBAB (tetrabutylammonium bromide). The pore-expanding agent provides a temporary support for the mesoporous channels and is removed during the subsequent drying and calcination process, thereby constructing abundant, interconnected, and size-controllable mesopores in the final catalyst, significantly improving the specific surface area and pore volume. The pore-expanding agent not only expands the pore size, but more importantly, it optimizes the uniformity and connectivity of the pore distribution. The pore-expanding agent exhibits dynamic competitive adsorption with the hydroxyl groups on the seed surface and the zirconium / silicon precursor, which can slow down the nucleation rate, extend the growth cycle, and promote more uniform coating of the seed crystal with silicon zirconium oxide to form a thin-walled, highly open hierarchical porous structure.

[0046] Furthermore, the concentration of the silicon source solution is 1~5 mol / L.

[0047] Preferably, the silicon source solution comprises silica sol.

[0048] Preferably, the silicon source in the silicon source solution includes at least one of water glass, silica gel powder, or tetraethyl silicate.

[0049] Furthermore, the concentration of the zirconium source solution is 0.03~1.5 mol / L.

[0050] Preferably, the zirconium source in the zirconium source solution includes at least one of zirconium sulfate, zirconium nitrate, zirconium oxynitrate, zirconium chloride, or zirconium oxychloride.

[0051] Furthermore, in the reaction system, the molar ratio of silicon source, zirconium source and seed crystal is 1:(0.1~0.8):(200~2000ppm).

[0052] Preferably, the pH of the reaction is 6 to 11.

[0053] Typically, but not limitingly, the pH of the reaction can be, for example, 6, 7, 8, 9, 10 or 11, or any value in the range of 6 to 11.

[0054] Furthermore, the preparation method involves adjusting the pH of the system by adding an acid solution or an alkaline solution.

[0055] Preferably, the acid solution comprises sulfuric acid and / or sodium bisulfate.

[0056] Preferably, the alkaline solution includes at least one of sodium hydroxide solution, ammonia water, sodium carbonate solution, and sodium bicarbonate solution.

[0057] Furthermore, the reaction temperature is 20~80℃ and the time is 2~36h.

[0058] Typically, but not limitingly, the reaction temperature can be, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C, or any value within the range of 20°C to 80°C; the reaction time can be, for example, 2h, 6h, 10h, 14h, 18h, 22h, 26h, 30h, 34h, or 36h, or any value within the range of 2 to 36h.

[0059] Preferably, the drying temperature is 50~120℃ and the time is 2~8h.

[0060] Typically, but not limitingly, the drying temperature can be, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, or any value within the range of 50°C to 120°C; the drying time can be, for example, 2h, 3h, 4h, 5h, 6h, 7h, or 8h, or any value within the range of 2h to 8h.

[0061] Preferably, the calcination temperature is 400~600℃ and the time is 4~12h. The high-temperature heat treatment completely removes physically adsorbed water, crystal water, organic template agents and volatile by-products from the precursor, promoting deep dehydration condensation of amorphous zirconium silicon hydroxide / hydrated oxide to form a crystalline-amorphous composite porous zirconium silicon oxide framework with a clear Zr–O–Si covalent bond network. This process not only achieves permanent fixation of the mesoporous structure and improvement of mechanical strength, but more importantly, it constructs and controls the type, density and strength of surface acid centers in situ.

[0062] Typically, but not limitingly, the roasting temperature can be, for example, 400°C, 450°C, 500°C, 550°C, or 600°C, or any value within the range of 400°C to 600°C; the roasting time can be, for example, 4h, 6h, 8h, 10h, or 12h, or any value within the range of 4h to 12h.

[0063] This invention also provides a method for using the catalyst, wherein a fixed-bed reactor is used in the propylene oligomerization reaction, with propylene as the raw material passing through in a single pass, and the propylene mass hourly space velocity (MHV) is 2-4 h⁻¹. -1 The catalyst usage is 100g, the reaction temperature is 150~200℃, and the reaction pressure is 3~5MPa.

[0064] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0065] Example 1 This embodiment provides a catalyst, and the specific preparation method is as follows: 1. Add 1.5g of ZSM-5 molecular sieve to 300mL of deionized water, disperse by ultrasonication for 10min, then add 3.65g of CTAB (hexadecyltrimethylammonium bromide), and stir at 40℃ for 2h to obtain a uniform and stable seed slurry.

[0066] 2. Dissolve 80g of water glass and 47.5g of zirconium sulfate (Zr(SO4)2·4H2O) in 100mL of deionized water to obtain silicon source solution and zirconium source solution respectively.

[0067] 3. Under the temperature control of a 75℃ water bath, add the silicon source solution and zirconium source solution to the seed slurry in step 1. During the dropwise addition, continuously add 5% (w / w) sulfuric acid aqueous solution to adjust the pH so that the pH of the reaction system is stably maintained at 6.5, and react at a constant temperature for 12 hours.

[0068] 4. After the solid reaction is completed, the filter cake is filtered and repeatedly washed with deionized water. The resulting wet filter cake is dried at 80°C for 6 hours and then calcined in a muffle furnace at 400°C for 8 hours. After natural cooling, it is shaped to obtain the catalyst.

[0069] Example 2 This embodiment provides a catalyst, and the specific preparation method is as follows: 1. Add 3.0g of MCM-41 molecular sieve to 300mL of deionized water, disperse by ultrasonication for 15min, add 2.2g of TPAB (tetrapropylammonium bromide), and stir at 30℃ for 3h to obtain a uniform and stable seed slurry.

[0070] 2. Dissolve 33.5g of silica sol and 10.5g of zirconium oxychloride (ZrOCl2·8H2O) in 80mL of deionized water to obtain silicon source solution and zirconium source solution respectively.

[0071] 3. Under a water bath temperature control at 60℃, the silicon source solution was first added to the seed slurry in one go and stirred for 30 minutes; then the zirconium source solution and 0.1 mol / L sodium carbonate aqueous solution were added dropwise simultaneously. The pH of the reaction system was kept stable at 8.0 by adjusting the dropping rate of the two solutions, and the reaction was carried out at a constant temperature for 8 hours.

[0072] 4. After the reaction is complete, filter the filter cake and wash it repeatedly with deionized water. The resulting wet filter cake is dried at 60°C for 4 hours and then calcined in a muffle furnace at 300°C for 6 hours. After natural cooling, it is shaped to obtain the catalyst.

[0073] Example 3 This embodiment provides a catalyst, and the specific preparation method is as follows: 1. Add 14g of SAPO-34 molecular sieve to 400mL of deionized water, disperse by ultrasonication for 15min, add 0.67g of ethylenediamine, and stir at 30℃ for 3h to obtain a uniform and stable seed slurry.

[0074] 2. Dissolve 29g of tetraethyl silicate and 24g of zirconium nitrate (Zr(NO3)4·5H2O) in 150mL of deionized water to obtain silicon source solution and zirconium source solution respectively.

[0075] 3. At room temperature, the zirconium source solution is added to the seed slurry all at once and stirred for 30 min. Then, the silicon source solution and 28 wt% ammonia solution are added dropwise simultaneously. The pH of the reaction system is kept stable at 10.5 by adjusting the dropping rate of the two solutions, and the reaction is carried out at a constant temperature for 36 h.

[0076] 4. After the reaction is complete, filter the filter cake and wash it repeatedly with deionized water three times. The resulting wet filter cake is dried at 100°C for 2 hours and then calcined in a muffle furnace at 600°C for 4 hours. After natural cooling, it is shaped to obtain the catalyst.

[0077] Example 4 This embodiment provides a catalyst, and the specific preparation method is as follows: 1. Add 14.0 g SAPO-34 molecular sieve to 400 mL of deionized water, disperse by ultrasonication for 20 min, add 2.5 g TEAB (tetraethylammonium bromide), and stir at 25℃ for 4 h to obtain a uniform and stable seed slurry.

[0078] 2. Dissolve 38.5g of tetraethyl silicate and 47.5g of zirconium nitrate in 150mL of deionized water to obtain silicon source solution and zirconium source solution respectively.

[0079] 3. Under a water bath temperature control at 45℃, the zirconium source solution was first added to the obtained seed crystal slurry in one go and stirred for 30 min; then the silicon source solution and 0.2 mol / L sodium bicarbonate aqueous solution were added dropwise simultaneously. By synergistically controlling the dropping rate of the two, the pH of the reaction system was kept stable at 10.0 and the reaction was carried out at a constant temperature for 24 h.

[0080] 4. After the reaction is complete, filter the filter cake and wash it repeatedly with deionized water three times. The resulting wet filter cake is dried at 110°C for 5 hours and then calcined in a muffle furnace at 500°C for 5 hours. After natural cooling, it is shaped to obtain the catalyst.

[0081] Example 5 This embodiment provides a catalyst, and the specific preparation method is as follows: 1. Add 20.0 g ZSM-5 molecular sieve and 5.0 g SAPO-34 molecular sieve to 500 mL deionized water, disperse by ultrasonication for 25 min, add 4.5 g TBAB (tetrabutylammonium bromide), and stir at 35 ℃ for 3.5 h to obtain a uniform and stable composite seed slurry.

[0082] 2. Dissolve 49.5g of water glass and 32.5g of zirconium oxynitrate (ZrO(NO3)2·2H2O) in 120mL of deionized water to obtain silicon source solution and zirconium source solution respectively.

[0083] 3. Under a water bath temperature control at 50℃, the silicon source solution and zirconium source solution were simultaneously added dropwise to the composite seed slurry. During the dropwise addition, a 0.5 mol / L sodium bisulfate aqueous solution was added dropwise simultaneously. The dropwise acceleration rate was adjusted by real-time online pH monitoring to keep the pH of the reaction system stable at 8.5. The reaction was carried out at this temperature for 12 h.

[0084] 4. After the reaction is complete, filter the filter cake and wash it repeatedly with deionized water three times. The resulting wet filter cake is dried at 90°C for 2 hours and then calcined in a muffle furnace at 450°C for 4 hours. After natural cooling, it is shaped to obtain the catalyst.

[0085] Example 6 This embodiment provides a catalyst. Unlike Example 3, in step 2, 29g of tetraethyl silicate and 3g of zirconium nitrate are dissolved in equal amounts of deionized water to obtain a silicon source solution and a zirconium source solution, respectively. The remaining steps are the same as in Example 3 and will not be repeated here.

[0086] Example 7 This embodiment provides a catalyst. Unlike Example 3, in step 2, 29g of tetraethyl silicate and 6g of zirconium nitrate are dissolved in equal amounts of deionized water to obtain a silicon source solution and a zirconium source solution, respectively. The remaining steps are the same as in Example 3 and will not be repeated here.

[0087] Example 8 This embodiment provides a catalyst. Unlike Example 3, in step 2, 29g of tetraethyl silicate and 48g of zirconium nitrate are dissolved in equal amounts of deionized water to obtain a silicon source solution and a zirconium source solution, respectively. The remaining steps are the same as in Example 3 and will not be repeated here.

[0088] Example 9 This embodiment provides a catalyst. Unlike Example 3, in step 2, 29g of tetraethyl silicate and 60g of zirconium nitrate are dissolved in equal amounts of deionized water to obtain a silicon source solution and a zirconium source solution, respectively. The remaining steps are the same as in Example 3 and will not be repeated here.

[0089] Comparative Example 1 This comparative example provides a catalyst, which is a ZSM-5 molecular sieve.

[0090] Comparative Example 2 This comparative example provides a catalyst. The difference between Example 3 and Example 4 is that only a zirconium source solution is added in step 3. All other steps are the same as in Example 3 and will not be repeated here.

[0091] Comparative Example 3 This comparative example provides a catalyst. The difference between Example 3 and Example 4 is that only a silicon source solution is added in step 3. All other steps are the same as in Example 3 and will not be repeated here.

[0092] Comparative Example 4 This comparative example provides a catalyst. The difference between Example 3 and Example 4 is that only TPAB (tetrapropylammonium bromide) is added to the seed slurry in step 1, and no molecular sieve is added. The other steps are the same as in Example 3, and will not be repeated here.

[0093] Comparative Example 5 This comparative example provides a catalyst. The difference between Example 3 and Example 4 is that only SAPO-34 molecular sieve is added to the seed slurry in step 1, and TPAB (tetrapropylammonium bromide) is not added. The other steps are the same as in Example 3, and will not be repeated here.

[0094] Test Example 1 The specific surface area of ​​the catalysts obtained in the examples and comparative examples was measured using an automatic adsorption apparatus, and the strength of the materials was measured using a particle strength tester. The data obtained are recorded in Table 1.

[0095] Table 1

[0096] As can be seen from Table 1, the prepared silicon-zirconium composite oxide catalyst has good mechanical strength; the addition of seed crystals and pore expanders can effectively increase the specific surface area of ​​the catalyst. Under the same seed crystals and pore expanders, the increase of zirconium content within a certain range can result in a large specific surface area.

[0097] Application Example 1 The catalysts obtained in the examples and comparative examples were evaluated for their reactivity using a fixed-bed reactor with propylene as feedstock in a single pass at a propylene mass hourly space velocity of 2-4 h⁻¹. -1 In the examples and comparative examples, the catalyst used was 100g, the reaction temperature was 150~200℃, and the reaction pressure was 3~5MPa.

[0098] Once the fixed-bed reactor feed system is operating stably and the deviation of the reactor outlet product composition from three consecutive sampling analyses is ≤2%, the reaction is considered stable and has reached the preset conditions. At this point, the first set of valid samples is collected for analysis, and the propylene conversion rate and nonene selectivity are statistically analyzed. The data are recorded in Table 2.

[0099] Table 2

[0100] As shown in Table 2, the silicon-zirconium oxide catalyst prepared with the addition of seed crystals and pore-expanding agents exhibits significant advantages in both reaction activity and selectivity compared to the comparative catalyst. The effect of zirconium content on the catalyst follows a clear pattern, initially increasing and then decreasing with increasing zirconium content. The silicon-zirconium oxide catalyst of this invention demonstrates high propylene conversion and good nonene selectivity.

[0101] Application Example 2 The catalyst provided in Example 3 was used in a reaction at a pressure of 4.5 MPa, a temperature of 200 °C, and a mass hourly space velocity of 2.0 h⁻¹. -1 Under the given conditions, starting from the point where the reaction is stable and the preset reaction conditions are reached, the timing is set, and the propylene conversion rate and nonene selectivity are statistically analyzed every 10 hours. The obtained data are plotted. Figure 1 .

[0102] from Figure 1As can be seen, after continuous operation for more than 300 hours, the time-varying curves of propylene conversion and nonene selectivity both show a flat trend, without significant inflection points or accelerated decline characteristics. This result indicates that the catalyst exhibits excellent structural stability and active site durability under operating conditions exceeding 300 hours, without showing obvious signs of deactivation such as acid center loss, pore collapse, or carbon deposition, fully verifying its core technological effectiveness in long-term industrial-grade operational stability.

[0103] Application Example 3 After the catalyst in use, corresponding to Case 2, is regenerated, it is subjected to a process at 4.5 MPa, 200 °C, and 2.0 h. -1 The reaction was carried out under certain conditions. After the reaction stabilized and the preset reaction conditions were reached, the data were statistically analyzed and are shown in Table 3.

[0104] Table 3

[0105] As can be seen from Table 3, the regenerated catalyst is basically equivalent to the original catalyst in terms of propylene conversion and nonene selectivity, demonstrating good regenerability and ensuring long-term stable use of the catalyst.

[0106] Test Example 2 For the catalyst after the reaction in Example 3, a TG-DTA spectrum was plotted, as follows: Figure 2 As shown in the figure. The TG-DTA analysis results show that: Thermogravimetric (TG) curve: During the heating process, the mass of the sample gradually decreases with increasing temperature, reaching the main stage of mass loss around 200℃, after which the mass change tends to level off. In the range of 450~500℃, the sample weight loss is less than 1%, with no significant mass loss.

[0107] Differential thermal analysis (DTA) curve: A weak exothermic peak appeared in the range of 450~500℃. Combined with the extremely small weight loss characteristics in this range, it can be determined that the exothermic peak was not caused by the combustion of a large amount of carbon deposits.

[0108] Based on the above information, the catalyst exhibits only a trace amount of mass loss and weak heat release during the reaction process, with no obvious carbon deposition, indicating that it is not prone to coking during the reaction process and therefore possesses good thermal and structural stability.

[0109] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A catalyst, characterized in that, The catalyst is used in the propylene oligomerization reaction; The catalyst is a porous silicon-zirconium oxide; The specific surface area of ​​the porous silicon zirconium oxide is not less than 260 m². 2 / g.

2. The catalyst according to claim 1, characterized in that, In the porous silicon-zirconium oxide, the molar ratio of silicon to zirconium is 1:(0.1~0.8), preferably 1:(0.2~0.7).

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that, The catalyst is obtained by adding silicon source solution and zirconium source solution to seed slurry, reacting, filtering, washing, drying and calcining.

4. The method for preparing the catalyst according to claim 3, characterized in that, The seed slurry contains seed crystals, a pore-expanding agent, and water; Preferably, the concentration of the seed crystals is 0.5~50 mmol / L; Preferably, the concentration of the pore-expanding agent is 0.02~0.04 mol / L.

5. The method for preparing the catalyst according to claim 4, characterized in that, The seed crystals include molecular sieves; Preferably, the molecular sieve includes at least one of ZSM-5, MCM-41, and SAPO-34; Preferably, the pore-expanding agent includes at least one of CTAB, ethylenediamine, n-butylamine, TEAB, TPAB, and TBAB.

6. The method for preparing the catalyst according to claim 3, characterized in that, The concentration of the silicon source solution is 1~5 mol / L; Preferably, the silicon source solution comprises silica sol; preferably, the silicon source in the silicon source solution comprises at least one of water glass, silica gel powder, or tetraethyl silicate.

7. The method for preparing the catalyst according to claim 3, characterized in that, The concentration of the zirconium source solution is 0.03~1.5 mol / L; Preferably, the zirconium source in the zirconium source solution includes at least one of zirconium sulfate, zirconium nitrate, zirconium oxynitrate, zirconium chloride, or zirconium oxychloride.

8. The method for preparing the catalyst according to any one of claims 3 to 7, characterized in that, In the reaction system, the molar ratio of silicon source, zirconium source and seed crystal is 1:(0.1~0.8):(200~2000ppm); Preferably, the pH of the reaction is 6 to 11.

9. The preparation method according to claim 8, characterized in that, Add acid or alkaline solutions to adjust the pH of the system; Preferably, the acid solution comprises sulfuric acid and / or sodium bisulfate; Preferably, the alkaline solution includes at least one of sodium hydroxide solution, ammonia water, sodium carbonate solution, and sodium bicarbonate solution.

10. The method for preparing the catalyst according to any one of claims 3 to 7, characterized in that, The reaction is carried out at a temperature of 20~80℃ for a time of 2~36h. Preferably, the drying temperature is 50~120℃ and the time is 2~8h; Preferably, the roasting temperature is 400~600℃ and the time is 4~12h.

Images