Silicon oxide microsphere as well as preparation method and application thereof

Abstract

The invention discloses a silicon oxide microsphere as well as a preparation method and application thereof. The silicon oxide microspheres are large-aperture silicon oxide microspheres, the specific surface area is 395-750m < 2 > / g, the pore volume is 1.0-3.5 ml / g, and the average aperture is 17-50nm. The silicon oxide microspheres have the characteristics of large specific surface area, large pore volume and large pore diameter, and the catalyst prepared by using the silicon oxide microspheres as the carrier has the advantage that the activity is remarkably improved when the catalyst is applied to olefin polymerization reaction.

Description

Technical Field

[0001] This invention belongs to the field of silicon oxide preparation, specifically relating to a silicon oxide microsphere, its preparation method, and its application. Background Technology

[0002] Silica microspheres are an important inorganic material that can be used as catalyst supports, biopharmaceutical carriers, and industrial additives. Silica is a commonly used support for petrochemical catalysts.

[0003] Due to significant differences in reactants, intermediate products, product sizes, and reaction mechanisms, different catalytic processes place varying requirements on the pore structure, pore distribution, specific surface area, and pore volume of catalyst supports. In the polymerization of low-carbon olefins such as ethylene and propylene, high-purity silica materials with a large specific surface area and large pore volume (average pore size between 10 nm and 50 nm) are excellent catalyst supports for polymerization reactions. Even subtle differences in the preparation process can significantly impact the polymerization performance of silica supports.

[0004] CN1978470A discloses a method for preparing a macroporous silica support for a gas-phase polymerization catalyst. The method involves reacting a 3%–20% (w / w) water glass solution and a 3%–20% (w / w) inorganic acid solution at a water glass:sulfuric acid weight ratio of 3–6:1 for 1–5 hours, adjusting the pH to 2–4 with the inorganic acid; washing the reactants until the sodium ion content is below 0.2%; then spray-drying the filter cake at 400–600°C; the washing method for the reactants includes one or more methods such as water washing and alcohol washing; and finally, the dried product is subjected to particle size classification to control the average particle size to 30–50 micrometers and the moisture content to below 10%, thus obtaining the macroporous silica support.

[0005] CN102079526A discloses a process for preparing high-purity macroporous silica gel, which uses silicates and inorganic acids as raw materials, and proceeds through gelation, aging, acidification, water washing, impurity removal, and drying. The impurity removal process uses inorganic acids, water-soluble organic acids, or inorganic acid salts and water-soluble organic acid salts as impurity removers, controlling the pH at 2–5, and reacting at 40–70°C for 1.0–3.0 hours. This method can reduce the Na and Fe content of the silica gel product to a few ten-thousandths without damaging the pore volume and pore size, demonstrating a significant impurity removal effect. The silica gel obtained by this method has a pore volume of 1.5–2.0 ml / g, a pore size of 18–25 nm, and a specific surface area of ​​260–350 m². 2 / g.

[0006] In the existing technology, silica microspheres are all derived from the drying and transformation of hydrogels with extremely high water content. Due to the high surface tension of water molecules, the presence of water molecules in the conventional drying process using water as a dispersant can easily cause the macroporous structure of the silica gel to collapse during the drying process, resulting in a significant reduction in the specific surface area and pore volume of the silica microspheres. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides silica microspheres, their preparation method, and applications. The silica microspheres possess large specific surface area, pore volume, and pore size. Furthermore, catalysts prepared using these silica microspheres as a support exhibit significantly enhanced activity in olefin polymerization reactions, achieving superior technical results.

[0008] The first aspect of this invention provides silica microspheres. The silica microspheres are macroporous silica microspheres with a specific surface area of ​​395–750 m². 2 / g, preferably 395~600m 2 / g, pore volume is 1.0~3.5ml / g, preferably 1.7~2.8ml / g, average pore size is 17~50nm, preferably 17~40nm.

[0009] According to the present invention, as a non-limiting example, the specific surface area of ​​the silica microspheres can be 400, 410, 420, 430, 440, 450, 470, 490, 500, 510, 530, 550, 570, 590, 610, 630, 650, 670, 700, 720, or 740 m². 2 Any value in / g.

[0010] According to the present invention, the average particle size of the silica microspheres is 20-80 μm.

[0011] A second aspect of the present invention provides a method for preparing the aforementioned silica microspheres. The method includes:

[0012] (1) Wash the silica gel with water and separate it to obtain intermediate product I;

[0013] (2) Mix the intermediate product I with alcohol A, perform alcohol treatment, and separate to obtain intermediate product II;

[0014] (3) The intermediate product II is mixed with a mixed solution of alcohol amine and alcohol B and pulped to obtain a slurry;

[0015] (4) The slurry is spray-dried to obtain silica microspheres.

[0016] According to the present invention, in step (1), the silica gel is prepared from a silica source solution. The specific preparation method of the silica gel includes: adjusting the pH of the silica source solution and aging it to obtain the silica gel.

[0017] According to the present invention, in the method for preparing silica gel, the silica source includes at least one selected from silica sol, water glass, and sodium silicate. The mass content of the silica source solution, calculated as silicon dioxide, is 2.5 wt% to 20 wt%. The pH value is adjusted to 5 to 10, preferably 6 to 9. The pH adjuster is selected from at least one selected from acidic and alkaline substances. The acidic substance is selected from at least one selected from hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, and oxalic acid. The alkaline medium is selected from at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and quaternary ammonium bases. The pH adjustment temperature is 20 to 95°C, preferably 20 to 80°C. The aging conditions are: an aging temperature of 20 to 95°C, preferably 50 to 80°C, and an aging time of 1 to 48 hours, preferably 3 to 24 hours.

[0018] According to the present invention, in step (1), the washing conditions are: temperature of 20-50°C and solid-liquid weight ratio of 0.5-3.0. The number of washing cycles is 1-8, preferably 2-8. The separation is at least one of centrifugal separation and filtration.

[0019] According to the present invention, in step (2), alcohol A is a water-soluble alcohol, preferably selected from at least one of ethanol and isopropanol. The conditions for alcohol treatment are: the alcohol treatment temperature is 10-30°C, and the duration of each alcohol treatment is 2-48 hours. The number of alcohol treatments is 1-6. Preferably, in each alcohol treatment, the weight ratio of alcohol A to intermediate product I is 0.5:1 to 3:1. The separation is centrifugal separation. The water content in intermediate product II is less than 15 wt%.

[0020] According to the present invention, in step (3), the alkanolamine includes at least one of monoethanolamine, diethanolamine, and triethanolamine. Alcohol B is a water-soluble alcohol, preferably selected from at least one of ethanol and isopropanol. Alcohol A and alcohol B can be the same or different. In the mixed solution of the alkanolamine and alcohol B, the weight ratio of alcohol B to alkanolamine is 3 to 10:1. As a non-limiting example, the weight ratio of alcohol B to alkanolamine can be any value among 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1. In the present invention, the alkanolamine and alcohol B work synergistically, which is beneficial to improving the overall performance of silica microspheres, such as specific surface area, pore volume, and pore size, and the polymerization activity of the olefin polymerization catalyst prepared from the obtained silica microspheres can be significantly improved.

[0021] According to the present invention, in step (3), the weight ratio of the mixed solution of the alkanolamine and alcohol B to the intermediate product II is 0.5:1 to 4:1, preferably 0.8:1 to 2:1. The pulping temperature is 20 to 60°C, preferably 30 to 45°C.

[0022] According to the present invention, in step (4), the spray drying is carried out in a centrifugal spray dryer, and the spray drying conditions are: inlet temperature of 200-450°C and outlet temperature of 105-180°C.

[0023] According to the present invention, in step (4), the content of metal impurities in the prepared silica microspheres is less than 0.8 wt%, preferably 0.0001% to 0.8 wt%; the metal impurities include at least one of alkali metals, alkaline earth metals, Fe, Co, Cu, Zn and Ni.

[0024] A third aspect of the present invention provides an olefin polymerization catalyst, wherein the silica microspheres are used as a support.

[0025] According to the present invention, the olefin polymerization catalyst uses the silica microspheres described herein as a support. The olefin polymerization catalyst also includes active components used in conventional olefin polymerization catalysts, such as one or more of the following metal elements: Mg, Cr, Ti, Al, Fe, Ni, Pd, and Zr. Based on the weight of the catalyst, the mass content of the metal element component is 0.1 wt% to 30 wt%. The precursor of the metal element can be derived from inorganic compounds or organic compounds, such as CN1040379A and CN1140722A.

[0026] According to the present invention, in the olefin polymerization catalyst, the mass content of the support is 70 wt% to 99.9 wt%, based on the weight of the catalyst.

[0027] The fourth aspect of this invention provides the application of the olefin polymerization catalyst in olefin polymerization reactions.

[0028] According to the present invention, the olefin is selected from at least one of ethylene, propylene and butene.

[0029] According to the present invention, the reaction conditions for the olefin polymerization include: a polymerization temperature of 50–150°C; a polymerization pressure of 0.4–5.5 MPa; and a polymerization time of 0.4–6 h. Preferably, the reaction conditions for the olefin polymerization include: a polymerization temperature of 60–90°C; a polymerization pressure of 0.6–4.0 MPa; and a polymerization time of 0.6–3.3 h.

[0030] Compared with the prior art, the advantages of this invention are as follows:

[0031] (1) This invention provides a novel silica microsphere, which is a large-pore silica microsphere with a specific surface area of ​​395–750 m². 2 The silica microspheres have a pore volume of 1.0–3.5 ml / g and an average pore size of 17–50 nm. These silica microspheres are suitable as supports for olefin polymerization catalysts.

[0032] (2) In the preparation method of silica microspheres of the present invention, silica sol is used as raw material, which is washed with water, treated with alcohol A, mixed and slurried with alkanolamine and alcohol B, and spray-dried to obtain the silica microspheres. The alcohol treatment in step (2) and the mixing and slurrying of the mixed solution of alkanolamine and alcohol B in step (3) have a synergistic effect, further improving the specific surface area, pore volume and pore size of the silica microspheres, as well as improving their polymerization activity in olefin polymerization reactions. The silica microspheres prepared by the preparation method provided by the present invention have a higher specific surface area, a larger pore size and a higher pore volume, and have better polymerization activity when used to prepare polymerization catalysts.

[0033] (3) The application of the catalyst prepared by the silica microspheres of the present invention as a support in the polymerization reaction, when ethylene is used as raw material, the polymerization index of the reaction can reach 4850.2gPE / gcat·h. Detailed Implementation

[0034] To make the present invention easier to understand, the present invention will be further described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0035] In this invention, the metal impurity content in Table 1 is determined by ICP method, which shows the elemental distribution and the calculation of the metal impurity element content. The testing instrument is a Varian 725ES from Varian.

[0036] In this invention, the method for determining the water content of intermediate product II (silicone gel washed with alcohol) in step (2) of each embodiment is as follows: Weigh 50g of alcohol-washed silicone gel, vacuum dry it in a closed vacuum system at 30°C and -0.5 atm until constant weight, collect the mass M of the alcohol-water mixture, and obtain the water content N of the alcohol-water mixture by chromatographic analysis. Then, the water content wt% of the alcohol-washed silicone gel is (M×N / 50)×100%.

[0037] In this invention, the specific surface area, pore volume, and average pore size of the silica microspheres were measured using the N2 physical adsorption method. The testing instrument was the Tri-Star physicochemical surface adsorption analyzer from Micron Instruments.

[0038] In this invention, the particle size of silica microspheres is characterized by the following method: a laser particle size analyzer is used for testing, specifically the Malvern Nano3000. The average particle size of the microspheres is the volume average particle size D(4,3).

[0039] In this invention, a small-scale batch polymerization reactor (10L) was used to test the polymerization activity index of the polymerization catalyst in each example. Taking ethylene as a raw material as an example, the specific method is as follows:

[0040] First, the reactor was preheated to 50°C and purged with nitrogen. Under stirring, 500 ml of p-xylene, 4 ml of triethylaluminum (0.001 mol / L), and 0.2 g of polymerization catalyst were injected in one step. The reaction temperature was 80°C, and the pressure was stabilized at 4.0 MPa using ethylene. The polymerization reaction was carried out, and after 1 hour, 20 ml of ethanol was added to terminate the reaction. The product was filtered, washed, and dried to obtain a white polyethylene product. The product was weighed and the activity index and polymerization index were calculated. The polymerization index is defined as the polymer mass (gPE) obtained per gram of catalyst per unit time (gcat·h).

[0041] Example 1

[0042] (1) Dilute an alkaline silica sol solution with a weight content of 40 wt% SiO2 (pH value = 9.5) with distilled water to prepare a silica source solution with a silica mass concentration of 15 wt%; adjust the pH of the silica source solution to 7.85 with 10 wt% dilute sulfuric acid at 60°C, and then age it at 60°C for 8 hours to obtain silica gel.

[0043] The silica gel was washed twice with water at 20°C and a solid-liquid weight ratio of 0.5:1. After centrifugation, intermediate product I was obtained.

[0044] (2) At a temperature of 20°C, 200g of intermediate product I was mixed with 200g of ethanol and stirred for 12h, and then the product was obtained by centrifugation.

[0045] The above ethanol treatment was repeated twice. Intermediate product II was obtained. The water content of intermediate product II was 9.8 wt%.

[0046] (3) Take 170g of ethanol and 30g of monoethanolamine and mix them evenly to obtain a mixed solution of ethanol and monoethanolamine.

[0047] At a temperature of 30°C, 200 g of the above mixed solution and 150 g of intermediate product II from step (2) were mixed and pulped using a colloid mill to obtain a slurry.

[0048] (4) The slurry was centrifugally spray-dried at an inlet temperature of 200°C and an outlet temperature of 120°C to obtain silica microspheres.

[0049] The properties of the silica microspheres in this example are shown in Table 1.

[0050] Using silica microspheres as a carrier, a polymerization catalyst was prepared using a conventional method. The specific steps included: under nitrogen protection, 50 ml of p-xylene was added to a reaction flask, followed by 2 ml of triethylaluminum (0.001 mol / L). The mixture was stirred at 50°C for 1 hour, then 2.5 g of silica microsphere carrier was added and soaked for 2 hours. The filtered solid was then dried in a vacuum oven at 30°C and -0.5 atm for 2 hours to remove the solvent. A mixed solution was prepared according to a weight ratio (TiCl3:MgCl2:tetrahydrofuran = 1:1.5:100), and 50 ml of this solution was injected into a reaction flask. The mixture was stirred at 50°C for 2 hours, and the filtered solid was dried in a vacuum oven at 30°C and -0.5 atm for 2 hours to remove the solvent. Then, 2 ml of a triethylaluminum toluene solution was added, and after 1 hour of treatment, the filtered solid was dried in a vacuum oven at 30°C and -0.5 atm for 2 hours to remove the solvent, yielding the polymerization catalyst. The activity test data of the polymerization catalyst are listed in Table 1.

[0051] Example 2

[0052] (1) Dilute an alkaline silica sol solution with a weight content of 40wt% SiO2 (pH value = 9.5) with distilled water to prepare a silica source solution with a silica mass concentration of 5wt%; adjust the pH of the silica source solution to 6 with 10wt% dilute sulfuric acid at 20℃, and then age it at 30℃ for 8 hours to obtain silica gel.

[0053] The silica gel was washed twice with water at 20°C and a solid-liquid weight ratio of 0.5:1. After centrifugation, intermediate product I was obtained.

[0054] (2) At a temperature of 20°C, 200g of intermediate product I was mixed with 400g of ethanol and stirred for 4 hours. After centrifugation, the product was obtained. Then, the above ethanol treatment operation was repeated twice to obtain intermediate product II. The water content of intermediate product II was 6.8 wt%.

[0055] (3) Take 180 grams of ethanol and 20 grams of monoethanolamine and mix them evenly to obtain a mixed solution of ethanol and monoethanolamine.

[0056] At a temperature of 30°C, 200 g of the above mixed solution and 150 g of intermediate product II from step (2) were mixed and pulped using a colloid mill to obtain a slurry.

[0057] (4) The slurry was centrifugally spray-dried at an inlet temperature of 200°C and an outlet temperature of 120°C to obtain silica microspheres.

[0058] The properties of the silica microspheres in this example are shown in Table 1.

[0059] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0060] Example 3

[0061] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the mixed solution of ethanol and monoethanolamine in step (3) of Example 1 was replaced with a mixed solution of ethanol and diethanolamine (where ethanol was 170g and diethanolamine was 30g), otherwise the same as in Example 1.

[0062] The properties of the silica microspheres in this example are shown in Table 1.

[0063] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0064] Example 4

[0065] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that ethanol in steps (2) and (3) of Example 1 was replaced with isopropanol; otherwise, the process was the same as in Example 1.

[0066] The properties of the silica microspheres in this example are shown in Table 1.

[0067] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0068] Example 5

[0069] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the number of ethanol washing steps (2) in Example 1 was changed to 4 times; otherwise, the process was the same as in Example 1.

[0070] The properties of the silica microspheres in this example are shown in Table 1.

[0071] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0072] Comparative Example 1

[0073] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the mixed solution of ethanol and monoethanolamine in step (3) of Example 1 was replaced with distilled water; otherwise, the process was the same as in Example 1.

[0074] The properties of the silica microspheres in this example are shown in Table 1.

[0075] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that step (2) alcohol treatment is omitted; otherwise, it is the same as Example 1.

[0078] The properties of the silica microspheres in this example are shown in Table 1.

[0079] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0080] Comparative Example 3

[0081] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the mixed solution of ethanol and monoethanolamine in step (3) of Example 1 was replaced with a mixed solution of ethanol and ethylamine (where ethanol was 170g and ethylamine was 30g), otherwise the same as in Example 1.

[0082] The properties of the silica microspheres in this example are shown in Table 1.

[0083] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0084] Comparative Example 4

[0085] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the mixed solution of 170g ethanol and 30g monoethanolamine in step (3) of Example 1 was replaced with a 200g ethanol solution (without adding monoethanolamine). Everything else was the same as in Example 1.

[0086] The properties of the silica microspheres in this example are shown in Table 1.

[0087] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0088] Comparative Example 5

[0089] Silica microspheres were prepared using the same method as in Example 1. The only difference from Example 1 was that the mixed solution of 170g ethanol and 30g monoethanolamine in step (3) of Example 1 was replaced with a 200g monoethanolamine solution (without adding ethanol). Everything else was the same as in Example 1.

[0090] The properties of the silica microspheres in this example are shown in Table 1.

[0091] Using silica microspheres as a carrier, the polymerization catalyst was prepared according to the same method as in Example 1. The activity test data of the polymerization catalyst in this example are listed in Table 2.

[0092] Table 1 Properties of each example of silica microspheres

[0093]

[0094]

[0095] Table 2 Activity test data for each polymerization catalyst

[0096] Polymerization activity index, gPE / gcat·h Example 1 4850.2 Example 2 4673.5 Example 3 5063.1 Example 4 5138.4 Example 5 4985.6 Comparative Example 1 2838.5 Comparative Example 2 2643.3 Comparative Example 3 3612.6 Comparative Example 4 3846.1 Comparative Example 5 4098.2

[0097] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A silica microsphere, characterized by, The silicon oxide microspheres are macroporous silicon oxide microspheres with a specific surface area of 395 to 750 m 2 / g, preferably 395 to 600 m 2 / g, preferably 1.7 to 2.8 ml / g, and an average pore diameter of 17 to 50 nm, preferably 17 to 40 nm.

2. The silica microspheres of claim 1, wherein, The average particle size of the silica microspheres is 20-80 μm.

3. A method for preparing the silica microspheres of claim 1 or 2, comprising: (1) washing and separating a silica gel to obtain an intermediate product I; (2) mixing the intermediate product I with an alcohol A to perform alcohol treatment, and separating to obtain an intermediate product II; (3) mixing and beating the intermediate product II with a mixed solution of an alcohol amine and an alcohol B to obtain a slurry; (4) performing spray drying on the slurry to obtain the silica microspheres.

4. The method of claim 3, wherein, In step (2), the alcohol A is a water-soluble alcohol, preferably at least one selected from the group consisting of ethanol and isopropanol; and / or, the alcohol treatment is performed at a temperature of 10-30 °C, and each alcohol treatment is performed for 2-48 h; the alcohol treatment is performed for 1-6 times; Preferably, in each alcohol treatment, the weight ratio of the alcohol A to the intermediate product I is 0.5:1-3:

1.

5. The method of claim 3, wherein, In step (3), the alcohol amine includes at least one selected from the group consisting of monoethanolamine, diethanolamine and triethanolamine; and / or, the alcohol B is a water-soluble alcohol, preferably at least one selected from the group consisting of ethanol and isopropanol; and / or, in the mixed solution of the alcohol amine and the alcohol B, the weight ratio of the alcohol B to the alcohol amine is 3-10:

1.

6. The method of claim 3, wherein, In step (3), the weight ratio of the mixed solution of the alcohol amine and the alcohol B to the intermediate product II is 0.5:1-4:1, preferably 0.8:1-2:

1.

7. The method of claim 3 wherein, In step (3), the beating is performed at a temperature of 20-60 °C, preferably 30-45 °C.

8. The method of claim 3, wherein, In step (4), the spray drying is performed in a centrifugal spray dryer, and the spray drying is performed at an inlet temperature of 200-450 °C and an outlet temperature of 105-180 °C.

9. An olefin polymerization catalyst characterized by, The silica microspheres of any one of claims 1-2 or prepared by the method of any one of claims 3-8 are used as carriers.

10. The use of the catalyst of claim 9 in an olefin polymerization reaction. Preferably, the reaction conditions for the polymerization of the olefin include: The polymerization temperature is 50-150 °C; The polymerization pressure is 0.4-5.5 MPa; The polymerization time is 0.4-6 h; Further preferably, the reaction conditions of the olefin polymerization include: the polymerization temperature is 60-90 °C; the polymerization pressure is 0.6-4.0 MPa; The polymerization time is 0.6-3.3 h.

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