A quaternary ammonium salt modified SiO2 nanomaterial, a preparation method and application thereof

Abstract

The application provides a quaternary ammonium salt modified SiO2 nano material, a preparation method and application thereof. Based on the surface modification technology of SiO2 nano microspheres, the quaternary ammonium salt modified SiO2 nano material is successfully prepared, the nano particle has a particle size of 50 nm, has good interface effect and oil displacement capacity; meanwhile, the nano particle synthesis and modification method applicable to a fracturing fluid system is formed, so that the nano particle can be better dispersed in a polymer clean fracturing fluid and has good compatibility and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil field chemistry, and particularly relates to a quaternary ammonium salt modified SiO2 nanomaterial, a preparation method and application thereof. BACKGROUND

[0002] Petroleum exploitation can be divided into three stages. Primary oil recovery is self-flowing production relying on formation energy, and the production accounts for about 5%-20% of the reserves. After the release of formation energy, artificial water injection or gas injection is used to supplement the reservoir energy and maintain the formation pressure, so that the crude oil can be continuously exploited, which is called secondary oil recovery, and the recovery rate is about 15%-20%. When the secondary oil recovery has been carried out for decades, the remaining oil is trapped in the sandstone pores of the reservoir in the form of discontinuous oil blocks, at this time, the produced liquid contains 85%-90% of water, and even as high as 98%, at this time, the exploitation has no economic benefits. Therefore, about 60%-70% of the crude oil can only be exploited by other physical and chemical methods, which is called tertiary oil recovery, and is also called EOR (Enhanced Oil Recovery) technology abroad.

[0003] At present, the polymer clean fracturing fluid oil displacement technology is widely used in the tertiary oil recovery technology in China. A large amount of polymers will be left in the underground when the polymer oil displacement is used, which not only causes waste but also causes difficulties in produced liquid treatment, and in many blocks, the oil production rapidly decreases after the polymer injection.

[0004] Therefore, it is an urgent problem to be solved in oil field exploitation to improve the existing polymer clean fracturing fluid system and improve the oil recovery rate. SUMMARY

[0005] In order to solve the above problems in the prior art, the present application provides a quaternary ammonium salt modified SiO2 nanomaterial, a preparation method and application thereof.

[0006] In a first aspect, the present application provides a quaternary ammonium salt modified SiO2 nanomaterial, which comprises SiO2 nanomicrospheres and groups grafted on the surface of the SiO2 nanomicrospheres as shown below.

[0007]

[0008] The particle size of the quaternary ammonium salt modified SiO2 nanomaterial is 10-80 nm.

[0009] As a specific embodiment of the present application, the quaternary ammonium salt modified SiO2 nanomaterial is prepared by a method comprising the following steps: heating reaction of SiO2 nanomicrospheres and quaternary ammonium salt.

[0010] In a second aspect, the present application provides a kind of quaternary ammonium modified SiO2 Nanomaterials and its preparation method, comprising the following steps: SiO2 Nanomicrosphere is reacted with quaternary ammonium salt.

[0011] As a specific embodiment of the present application, the SiO2 Nanomicrosphere is prepared by sol-gel method using tetraethyl orthosilicate as silicon source. Its reaction equation is as follows:

[0012] nSi (OC2H5) 4+4nH2O→nSi (OH) 4+4nC2H5OH (hydrolysis)

[0013] nSi (OH) 4→nSiO2+2nH2O (polycondensation)

[0014] As a specific embodiment of the present application, the method for preparing SiO2 Nanomicrosphere comprises the following steps:

[0015] S11: mixing tetraethyl orthosilicate with ethanol to obtain a first solution;

[0016] S12: mixing deionized water, concentrated ammonia and ethanol, and stirring uniformly to obtain a second solution;

[0017] S13: mixing the first solution with the second solution, and stirring and evaporating to obtain a concentrated solution;

[0018] S14: adding the concentrated solution obtained in step S13 into toluene, stirring, centrifuging and volatilizing to obtain white SiO2 solid.

[0019] As a specific embodiment of the present application, in step S11, the volume ratio of tetraethyl orthosilicate TEOS to anhydrous ethanol is (4-5):100.

[0020] As a specific embodiment of the present application, in step S12, the volume ratio of deionized water, concentrated ammonia and ethanol is (0.1-1):(5-10):80; and the concentration of the concentrated ammonia is 25%-28% by weight.

[0021] As a specific embodiment of the present application, the mixing mode of the first solution and the second solution is not limited, and they can be mixed uniformly; as a preferred embodiment of the present application, the stirring mode is preferably magnetic stirring, and the stirring time is preferably 0.5-2h.

[0022] As a specific embodiment of the present application, in step S13, the mixing mode of the first solution and the second solution is not limited, and to make the reaction more complete, preferably, the first solution is added to the second solution drop by drop using a burette; preferably, the first solution and the second solution are further mixed uniformly by stirring; more preferably, the stirring time is 15-24h.

[0023] As a specific embodiment of the present application, the evaporation method is preferably rotary evaporation, and the specific parameters are preferably: pressure less than 0.01 MPa, and temperature 20-50℃.

[0024] As a specific embodiment of the present application, the concentrated solution is concentrated to 5%-10% of the original volume.

[0025] As a specific embodiment of the present application, in step S14, the concentrated solution is added to toluene without limitation, and to achieve more complete reaction, it is preferably added drop by drop using a burette. For example, for 6 ml of concentrated solution, the addition rate can be 1 d / s.

[0026] As a specific embodiment of the present application, the stirring method is preferably high-speed stirring of the rotor for 1-5 min.

[0027] As a specific embodiment of the present application, the SiO2 nanospheres are washed with anhydrous ethanol at least 3 times before centrifugation.

[0028] As a specific embodiment of the present application, the operation of heating the SiO2 nanospheres with the quaternary ammonium salt comprises:

[0029] S21: mixing the nanometer SiO2 obtained in step S14 with toluene, water, and γ-chloropropyltrimethoxysilane, heating and reacting, toluene extraction, and drying to obtain γ-chloropropyltrimethoxysilane-modified nanometer silicon dioxide;

[0030] S22: mixing the γ-chloropropyltrimethoxysilane-modified nanometer silicon dioxide with N,N-dimethyltetradecyl tertiary amine, heating and reacting, acetonitrile extraction, vacuum drying, to obtain N,N-dimethyltetradecyl tertiary amine-modified quaternary ammonium salt-modified SiO2 nanomaterial.

[0031] Specifically, the reaction equation for bonding the quaternary ammonium salt to the surface of the nanometer SiO2 is as follows:

[0032]

[0033] As a specific embodiment of the present application, in step S21, the amount ratio of the SiO2 nanospheres to γ-chloropropyltrimethoxysilane is 5 g: 0.02-0.04 mol, preferably 5 g: 0.03-0.04 mol, for example 5 g: 0.0341 mol.

[0034] As a specific embodiment of the present application, the mass-volume ratio of the SiO2 nanospheres to toluene, water, and γ-chloropropyltrimethoxysilane is 3-8 g: 40 ml: 1-5 ml.

[0035] As a specific embodiment of the present application, the heating temperature is 80-90℃, and the reaction is performed for 5-10 h.

[0036] As a specific embodiment of the present application, in the step S22, the mass ratio of the gamma-chloropropyltrimethoxysilane modified nano-silica to N,N-dimethyltetradecyl tertiary amine is (0.8-1.2):1.

[0037] The above raw materials in the present application can be self-made or commercially available, and the present application does not particularly limit this.

[0038] In a third aspect, the present application provides an application of the quaternary ammonium salt modified SiO2 nano-material in the field of fracturing fluid.

[0039] As a specific embodiment of the present application, the quaternary ammonium salt modified SiO2 nano-material is uniformly dispersed in the existing fracturing fluid.

[0040] As a specific embodiment of the present application, the addition amount of the quaternary ammonium salt modified SiO2 nano-material is 0.1% to 2%.

[0041] The dispersion method is preferably ultrasonic wave combined with mechanical stirring; the dispersion time of the quaternary ammonium salt modified SiO2 nano-material is 3 to 8 hours; preferably, the dispersion time is 5 hours.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] 1. Based on the surface modification technology of SiO2 nano-microsphere, the quaternary ammonium salt modified SiO2 nano-material is successfully prepared, and its compatibility, stability and surface tension are studied. At the same time, aiming at its oil displacement capacity, a quaternary ammonium salt modified SiO2 nano-material oil displacement kinetics model and adsorption configuration are established, and its adsorption energy is calculated.

[0044] 2. The quaternary ammonium salt modified SiO2 nano-material synthesized in the present application has a particle size of 50 nm and has good interface effect. At the same time, a set of nano-particle synthesis and modification method applicable to the fracturing fluid system is formed, so that the nano-particles can be better dispersed in the polymer clean fracturing fluid, and have good compatibility and stability. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a schematic diagram of the formation process of the monodisperse nano-SiO2 spherical particles of the present application;

[0046] Figure 2 It is an infrared spectrum of SiO2 nano-material and quaternary ammonium salt modified SiO2 nano-material;

[0047] Figure 3a It is a SEM image (50 times) of the quaternary ammonium salt modified SiO2 nano-material microsphere;

[0048] Figure 3b SEM image (100x) of SiO2 nanomaterial microspheres modified with quaternary ammonium salt;

[0049] Figure 4a Elemental analysis of C in quaternary ammonium salt modified SiO2 nanomaterials;

[0050] Figure 4b H elemental analysis diagram of quaternary ammonium salt modified SiO2 nanomaterials;

[0051] Figure 4c Elemental analysis of nitrogen in quaternary ammonium salt modified SiO2 nanomaterials;

[0052] Figure 5 The compatibility and stability of quaternary ammonium salt modified SiO2 nanomaterials in fracturing fluid;

[0053] Figure 6 This is a bar chart showing the dispersion time of SiO2 nanomaterials modified with quaternary ammonium salts at different concentrations in Example 2 in fracturing fluid.

[0054] Figure 7a The rheological properties of the medium-viscosity fracturing fluid-SiO2 nanomaterials without quaternary ammonium salt modification are shown in the graph.

[0055] Figure 7b The rheological properties of the medium-viscosity fracturing fluid-SiO2 nanomaterials modified with 1% quaternary ammonium salt are shown in the graph.

[0056] Figure 7c The rheological properties of high-viscosity fracturing fluid-SiO2 nanomaterials without quaternary ammonium salt modification are shown in the graph.

[0057] Figure 7d The rheological properties of the high-viscosity fracturing fluid-SiO2 nanomaterials modified with 1% quaternary ammonium salt are shown in the graph.

[0058] Among them, the infrared spectrum curves of 1-SiO2 nanomaterials and 2-quaternary ammonium salt modified SiO2 nanomaterials are shown. Detailed Implementation

[0059] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0060] The water-based fracturing fluid mainly comprises: 0.2-0.45% thickener, 0.3% crosslinking agent, 2% KCl, 0.1% flow aid, 1% nano-displacement agent, and the remainder is water. The medium-viscosity fracturing fluid used in the embodiments of this invention has a viscosity of 16 mPa·s and contains 0.2% thickener; the high-viscosity fracturing fluid has a viscosity of 34 mPa·s and contains 0.35% thickener.

[0061] The experimental instrument for the elemental analysis experiment in each embodiment of the present application is a U.S. thermal Flash EA1112CHNS-0 elemental analyzer; the experimental parameters are: furnace temperature 900 DEG C, detector 65 DEG C, reference gas (He): 100 ml / min; carrier gas (He): 140 ml / min; oxygen: 140 ml / min.

[0062] The surface tension coefficient in each embodiment of the present application is tested by a capillary method.

[0063] The experimental instrument for the interfacial surface tension test in each embodiment of the present application is a German KRUSS interfacial surface tension meter, model K100.

[0064] Example 1

[0065] The present embodiment provides a quaternary ammonium salt modified SiO2 nanomaterial, a preparation method and application thereof, and prepares SiO2 nanospheres and quaternary ammonium salt modified SiO2 nanomaterials, and the specific details are as follows:

[0066] Step 1: Synthesis of SiO2 nanospheres

[0067] S11: 4.6ml of TEOS was mixed with 100ml of anhydrous ethanol and stirred at room temperature for 1h by a magnetic stirrer to obtain a first solution;

[0068] S12: 0.4ml of deionized water, 7.6ml of concentrated ammonia water with a concentration of 25wt%, and 80ml of anhydrous ethanol were mixed and stirred at room temperature for 1h by a magnetic stirrer to obtain a second solution;

[0069] S13: The first solution was added dropwise to the second solution, and stirred at room temperature for 20h to obtain a mixed solution;

[0070] S14: The mixed liquid was subjected to rotary evaporation, the pressure was controlled at-0.095MPa, and the temperature was controlled at 35 DEG C, and concentrated to 6ml to obtain a concentrated solution;

[0071] S15: The concentrated solution was added dropwise to 10ml of toluene at a speed of 1d / s, and then stirred at high speed for 2min by a rotor, washed with anhydrous ethanol, and centrifuged three times, and then naturally volatilized to obtain white SiO2 solid.

[0072] Step 2: Synthesis of quaternary ammonium salt modified SiO2 nanomaterial

[0073] S21: 5g of nano-SiO2 was added into 40ml of toluene, stirred for 30min, 2ml of water was added, and 0.0341mol (6.3ml) of γ-chloropropyltrimethoxysilane was added dropwise under stirring, heated to 85°C, reacted for 6h, filtered to obtain γ-chloropropyltrimethoxysilane modified nano-SiO2,

[0074] The obtained product was extracted with toluene in a Soxhlet extractor for 24h, and unreacted γ-chloropropyltrimethoxysilane was removed, and vacuum dried (60°C);

[0075] S22: The γ-chloropropyltrimethoxysilane modified nano-silica was stirred in acetonitrile for 30min, 9.2ml of 0.03mol N,N-dimethyltetradecyl tertiary amine was added dropwise under stirring, heated and reacted, extracted with acetonitrile for 24h, and vacuum dried to obtain pure N,N-dimethyltetradecyl tertiary amine modified quaternary ammonium salt modified SiO2 nanomaterial.

[0076] The quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 was subjected to infrared spectrum analysis, as shown in Figure 2 The infrared spectrum characteristic peaks of the quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 were compared with those of the existing SiO2 nanomaterial, and it was found that the quaternary ammonium salt was successfully grafted onto the surface of the nanomaterial SiO2 prepared in Example 1.

[0077] The quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 was subjected to SEM scanning electron microscope observation, as shown in Figure 3a 、 3b The average particle size of the quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 was 50nm.

[0078] The quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 and SiO2 nanomicrosphere were subjected to elemental analysis, as shown in Figure 4a 、 4b , 4c, and the data in Table 1 also indicated that the quaternary ammonium salt was successfully grafted onto the surface of SiO2.

[0079] Table 1 C, H, N elemental analysis of quaternary ammonium salt modified SiO2 nanomaterial

[0080] Sample C(％) H(％) N(％) SiO2 0.000 3.797 0.000 SiO2-QAS 11.086 5.918 1.203

[0081] The quaternary ammonium salt modified SiO2 nanomaterial obtained in Example 1 was dispersed in a medium viscosity fracturing fluid at a proportion of 0.5%, and left overnight to observe the agglomeration phenomenon of the nanoparticles, as shown in Figure 5 The results showed that the quaternary ammonium salt modified SiO2 nanomaterial had good compatibility and stability in the fracturing fluid

[0082] Example 2

[0083] This embodiment provides the application of the quaternary ammonium salt modified SiO2 nanomaterials prepared in Example 1 in fracturing fluid, and obtains an optimal formulation scheme, the details of which are as follows:

[0084] The quaternary ammonium salt modified SiO2 nanomaterials prepared in Example 1 were taken in doses of 0.02 g, 0.1 g, 0.2 g, and 0.4 g respectively and dispersed in 20 ml of medium viscosity fracturing fluid to obtain fracturing fluids with quaternary ammonium salt modified SiO2 nanomaterials in proportions of 0.1%, 0.5%, 1%, and 2% respectively. The dispersibility of the fracturing fluids was tested by ultrasonic treatment combined with mechanical stirring.

[0085] Distributed test results, such as Figure 6 As shown, the quaternary ammonium salt modified SiO2 nanomaterials exhibit the best dispersibility at a dosage of 0.5%, with a dispersion time of only 4 hours. The optimal dosage of quaternary ammonium salt modified SiO2 nanomaterials is 1%, followed by 0.5%.

[0086] Test case

[0087] This test example involves various performance tests on the fracturing fluids with different formulations obtained in Example 2, and comparisons are made with SiO2 nano-fracturing fluids. Specific details are as follows:

[0088] The SiO2 nanospheres prepared in step 1 of Example 1 were also dispersed in medium-viscosity fracturing fluid at proportions of 0.1%, 0.5%, 1%, and 2% respectively, using an ultrasonic-mechanical stirring method for 4 hours to obtain 0.1% SiO2 nano-medium-viscosity fracturing fluid, 0.5% SiO2 nano-medium-viscosity fracturing fluid, 1% SiO2 nano-medium-viscosity fracturing fluid, and 2% SiO2 nano-medium-viscosity fracturing fluid. These were compared with the medium-viscosity fracturing fluids obtained in Example 2, which contained 0.1%, 0.5%, 1%, and 2% quaternary ammonium salt modified SiO2 nanomaterials. Various comparative tests were then performed.

[0089] Surface tension coefficient test

[0090] The surface tension coefficients of the medium-viscosity fracturing fluids and the medium-viscosity fracturing fluids of quaternary ammonium salt modified SiO2 nanomaterials with the above-mentioned proportions of 0.1%, 0.5%, 1%, and 2% were tested using the capillary method. The results are shown in Table 2.

[0091] Table 2 shows the results of surface tension coefficient measurements for fracturing fluids with different formulations obtained in Example 2.

[0092]

[0093]

[0094] The results show that the addition of the quaternary ammonium salt modified SiO2 nanomaterials can effectively reduce the surface tension coefficient of the fracturing fluid, and is conducive to avoiding the damage to the reservoir caused by the water blocking effect and the Jamin effect.

[0095] Rheological property test

[0096] The above-mentioned dispersing is added into the high viscosity fracturing fluid in the proportions, i.e. 0.1% of the quaternary ammonium salt modified SiO2 nanomaterials high viscosity fracturing fluid, 0.5% of the quaternary ammonium salt modified SiO2 nanomaterials high viscosity fracturing fluid, 1% of the quaternary ammonium salt modified SiO2 nanomaterials high viscosity fracturing fluid, and 2% of the quaternary ammonium salt modified SiO2 nanomaterials high viscosity fracturing fluid. And the test is compared with the different proportions of the quaternary ammonium salt modified SiO2 nanomaterials in the viscosity fracturing fluid prepared in Example 2, as shown in Figure 7: Figure 7a and Figure 7b The rheological curves of the medium viscosity fracturing fluid before and after adding 1% of the quaternary ammonium salt modified SiO2 nanomaterials are compared, Figure 7c and 7d The rheological curves of the high viscosity fracturing fluid before and after adding 1% of the quaternary ammonium salt modified SiO2 nanomaterials.

[0097] Interfacial tension test of the fracturing fluid

[0098] The interfacial tension of the fracturing fluid before and after adding 1% of the quaternary ammonium salt modified SiO2 nanomaterials is tested, and the results are shown in Table 3 and Table 4,

[0099] Table 3 Surface tension of the fracturing fluid before and after adding 1% of the quaternary ammonium salt modified SiO2 nanomaterials

[0100]

[0101] Table 4 Interfacial tension of the fracturing fluid before and after adding 1% of the quaternary ammonium salt modified SiO2 nanomaterials

[0102]

[0103]

[0104] The experimental results prove that the interfacial tension of the clean fracturing fluid is obviously decreased after adding the quaternary ammonium salt modified SiO2 nanomaterials, the surface tension of the fracturing fluid added with the nanomaterials is significantly reduced, which shows a good oil displacement effect.

[0105] In conclusion, the prepared quaternary ammonium salt modified SiO2 nanomaterial has a particle size of 50 nm and has good interface effect.

[0106] Any numerical values recited herein include all values from the lower value and the upper value in between. For example, if a component is stated as 50-90, it is intended that values such as 51-89, 52-88, 53-87, 54-86, 55-85, 56-84, 57-83, 58-82, 59-81, 60-80, 61-79, 62-78, 63-77, 64-76, 65-75, 66-74, 67-73, 68-72, 69-71, 70-71, and the like are specifically contemplated. For values which are not integers, unit of 0.1, 0.01, 0.001, or 0.0001 are contemplated. These are only some specific examples of what is specifically contemplated by this application. In this application, similar described numerical ranges using similar language are also contemplated.

[0107] It should be noted that the foregoing examples have been provided merely for the purposes of explanation and are in no way to be construed as limiting. The present application is described with reference to exemplary embodiments, but it is understood that the words which have been used herein are words of description, and that the application is not limited to the particulars of the embodiments described. The present application is capable of modification in various respects, and the applicant intends to be bound by the application only as described in the request. Although the application has been described in connection with specific embodiments thereof, it will be understood that the application is capable of further modifications. This application is intended to cover any variations, uses or adaptations of the application following, in general, the principles of the application, and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. While the preferred embodiment has been described, additional variations and modifications can occur to those skilled in the art once advised of the applications disclosed herein, and such variations and modifications are intended to fall within the scope of the applications as described herein. Although the application has been described in connection with specific embodiments, it will be understood that the application is capable of further modifications. This application is intended to cover any variations, uses or adaptations of the application following, in general, the principles of the application, and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. While the preferred embodiment has been described, additional variations and modifications can occur to those skilled in the art once advised of the applications disclosed herein, and such variations and modifications are intended to fall within the scope of the applications as described herein.

Claims

1. Application of a quaternary ammonium salt modified SiO2 nanomaterial in the field of fracturing fluid, characterized in that, The SiO2 nanomaterial comprises SiO2 nanomicrospheres and groups grafted on the surface of the SiO2 nanomicrospheres, as shown below: The SiO2 nanomaterial has a particle size of 10-80 nm; the quaternary ammonium salt modified SiO2 nanomaterial is uniformly dispersed in the fracturing fluid, and the addition amount of the quaternary ammonium salt modified SiO2 nanomaterial is 0.1%-2%; The preparation method of the quaternary ammonium salt modified SiO2 nanomaterial comprises the following steps: heating and reacting SiO2 nanomicrospheres with a quaternary ammonium salt. The operation of heating and reacting SiO2 nanomicrospheres with a quaternary ammonium salt comprises the following steps: S21: uniformly mixing SiO2 nanomicrospheres with toluene, water and γ-chloropropyltrimethoxysilane, heating and reacting, toluene extraction, and drying to obtain γ-chloropropyltrimethoxysilane modified nanosilica; S22: mixing the γ-chloropropyltrimethoxysilane modified nanosilica with N,N-dimethyltetradecylamine, heating and reacting, acetonitrile extraction, vacuum drying, and obtaining N,N-dimethyltetradecylamine modified quaternary ammonium salt modified SiO2 nanomaterial.

2. Use according to claim 1, characterized in that, The SiO2 nanomicrospheres are prepared by a sol-gel method using tetraethyl orthosilicate as a silicon source.

3. Use according to claim 2, characterized in that, The method for preparing SiO2 nanomicrospheres comprises the following steps: S11: mixing tetraethyl orthosilicate with ethanol to obtain a first solution; S12: mixing deionized water, concentrated ammonia and ethanol, and stirring to obtain a second solution; S13: mixing the first solution with the second solution, and stirring and evaporating to obtain a concentrated solution; S14: adding the concentrated solution obtained in step S13 to toluene, stirring, centrifuging and volatilizing to obtain white SiO2 solid.

4. Use according to claim 3, characterized in that, In step S11, the volume ratio of tetraethyl orthosilicate to ethanol is (4-5):

100.

5. Use according to claim 3, characterized in that, In step S12, the volume ratio of deionized water, concentrated ammonia and ethanol is (0.1-1):(5-10):80; and / or The concentration of the concentrated ammonia is 25%-28% by weight.

6. Use according to claim 3, characterized in that, In step S13, the first solution is added to the second solution dropwise by means of a burette; and / or The evaporation is performed by rotary evaporation, and the specific parameters are: pressure lower than 0.01 MPa, and temperature of 20-50°C; and / or The concentrated solution is concentrated to 5%-10% of the original volume.

7. Use according to claim 3, characterized in that, In step S14, the concentrated solution is added to toluene dropwise by means of a burette; and / or The concentrated solution is washed with anhydrous ethanol at least 3 times before centrifuging.

8. The use according to claim 1, characterized in that, In step S21, the amount ratio of SiO2 nanomicrospheres to γ-chloropropyltrimethoxysilane is 5 g:0.02-0.04 mol; and / or The mass-volume ratio of SiO2 nanomicrospheres to toluene, water and γ-chloropropyltrimethoxysilane is (3-8) g:40 ml:(1-5) ml; and / or The heating temperature is 80-90°C, and the reaction time is 5-10 h.

9. Use according to claim 8, characterized in that, In step S21, the amount ratio of SiO2 nanomicrospheres to γ-chloropropyltrimethoxysilane is 5 g:0.03-0.04 mol.

10. Use according to claim 9, characterized in that, The ratio of the SiO2 nanospheres to the γ-chloropropyl trimethoxysilane in the step S21 is 5 g:0.0341 mol.

11. Use according to claim 1, characterized in that, The ratio of the γ-chloropropyl trimethoxysilane modified nanosilica to the N,N-dimethyltetradecyl tertiary amine in the step S22 is (0.8-1.2):1.

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