CN111533133A - Silicon dioxide aerogel microsphere and preparation method and application thereof - Google Patents

Silicon dioxide aerogel microsphere and preparation method and application thereof Download PDF

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CN111533133A
CN111533133A CN202010271053.2A CN202010271053A CN111533133A CN 111533133 A CN111533133 A CN 111533133A CN 202010271053 A CN202010271053 A CN 202010271053A CN 111533133 A CN111533133 A CN 111533133A
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silica aerogel
aerogel microspheres
silicon source
aging
microspheres
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孔令汉
程量
詹建波
张莹
李赓
余婷婷
王浩
王旭
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China Tobacco Yunnan Industrial Co Ltd
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    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/152—Preparation of hydrogels
    • A—HUMAN NECESSITIES
    • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
    • A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
    • A24D3/06—Use of materials for tobacco smoke filters
    • A24D3/16—Use of materials for tobacco smoke filters of inorganic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28016—Particle form
    • B01J20/28021—Hollow particles, e.g. hollow spheres, microspheres or cenospheres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28047—Gels
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/141—Preparation of hydrosols or aqueous dispersions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C01B33/158—Purification; Drying; Dehydrating
    • C01B33/1585—Dehydration into aerogels
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
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    • C01P2006/12—Surface area

Abstract

The invention belongs to the technical field of adsorption, and particularly relates to a silicon dioxide aerogel microsphere as well as a preparation method and application thereof. The silica aerogel microspheres have hydrophobicity, the particle size of the silica aerogel microspheres is 250-1000 mu m, and the density of the silica aerogel microspheres is 0.05-0.20 g/cm3The specific surface area is 400-1000 m2(ii) in terms of/g. The invention also discloses a preparation method and application of the silicon dioxide aerogel microspheres. The aerogel microspheres prepared by the invention have good hydrophobicity and balling property and excellent adsorption performance, can be applied to cigarette filter sticks for adsorbing side-stream smoke of cigarettes and loading essence perfume, and can also be applied to more fields with special requirements such as sewage treatment, chromatographic packing and the like.

Description

Silicon dioxide aerogel microsphere and preparation method and application thereof
Technical Field
The invention belongs to the technical field of adsorption, and particularly relates to a silicon dioxide aerogel microsphere as well as a preparation method and application thereof.
Background
The porous material loading system is a relatively common depot sustained release system, and the storage and release of the fragrance material depends on the properties of the porous material, and generally has the following characteristics: (1) inert per se, or inert in the target environment, or have special effects; (2) the material has a porous structure and a large specific surface area; (3) for some objects (such as perfume), the inner surface of the porous material has certain special functional groups; (4) the price is low and is common; (5) green and non-toxic. The cyclodextrin, the porous starch, the porous silicon material and the like are widely applied in the field of flavor and fragrance. In recent years, the preparation process of the silicon-based porous material is well developed, and the silica aerogel is one of typical materials.
The silica aerogel is a light porous amorphous material, and the main structural formula of the silica aerogel is a continuous three-dimensional network structure formed by mutually aggregating silica nano-scale ultrafine particles. The silica aerogel structure consists of network pores with volume fraction of more than 90 percent and SiO with volume fraction of less than 10 percent2The skeleton is composed of pores filled with gaseous dispersing medium. SiO 22The structure of the aerogel gives the aerogel extremely low thermal conductivityHigh heat resistance stability and excellent adsorption performance. Can be used for sidestream smoke adsorption of cigarette and loading of essence and spice.
The aerogel density is extremely low, and the current lightest silicon aerogel is only 3mg/cm3(the density of air is 1.29kg/m3) And is therefore also called "frozen smoke" or "blue smoke". This will also lead to the aerogel material in the use of cigarette products, once the control conditions to the aerogel powder is not enough, will lead to the aerogel powder to fly away in the form of "cigarette" in the burning process of cigarette, and then follow the flue gas and be inhaled by the human body in vivo, remain in the lung, harm human health. It is therefore contemplated to modify the morphological structure of the aerogel sample to reduce such hazards, as by replacing it with aerogel microspheres. The aerogel microspheres are prone to caking during combustion to form densified caking. The microspheres have certain roundness and certain form stability. During processing, storage, transportation and use, no environmental pollution and no human harm caused by powder floating.
In the process of implementing the invention, the inventor finds that the prior art has at least the following problems:
the specific surface area of the microspheres prepared by the existing method is usually 400m2About/g, and the performance of the adsorbent is not excellent enough when the adsorbent is applied to the adsorption field. And some preparation methods need sol exchange and surface modification steps, so that the use of solvents is increased, the preparation cost is higher, and the toxicity is increased.
The present invention has been made to solve the above problems.
Disclosure of Invention
The first aspect of the invention provides silica aerogel microspheres, wherein the silica aerogel microspheres have hydrophobicity, the particle size of the silica aerogel microspheres is 250-1000 microns, and the density of the silica aerogel microspheres is 0.05-0.20 g/cm3The specific surface area is 400-1000 m2/g。
The second aspect of the present invention provides a method for preparing the silica aerogel microspheres described in the first aspect, the method comprising the steps of:
(1) respectively adding acid catalysts into the first silicon source and the second silicon source for hydrolysis to obtain a first precursor hydrolysate and a second precursor hydrolysate; wherein the first silicon source is hydrolyzed to generate silicon hydroxyl and does not contain organic groups; the second silicon source at least contains one non-hydrolytic group;
(2) mixing the first precursor hydrolysate and the second precursor hydrolysate in proportion to form mixed sol, adding an alkali catalyst, and adjusting the pH value of the solution;
(3) before the mixed sol obtained in the step (2) does not have an initial gel state, transferring the mixed sol into an emulsifier and stirring to form white wet gel balls;
(4) immersing the wet gel pellets obtained in the step (3) with a solvent, aging, and filtering to obtain solid pellets;
(5) drying the solid pellets obtained in the step (4) to obtain the silicon dioxide aerogel microspheres;
the preparation method of the silica aerogel microspheres does not comprise the steps of solvent exchange and surface modification.
Preferably, the second silicon source is an organosiloxane containing one or more hydrocarbon groups.
Preferably, step (1) includes any one or a combination of the following features:
(a) the first silicon source is selected from tetraethyl orthosilicate, tetramethyl orthosilicate or water glass;
(b) the second silicon source is selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or dimethyldimethoxysilane;
(c) the acid catalyst is one or more of hydrofluoric acid, hydrochloric acid, sulfuric acid, oxalic acid and acetic acid;
(d) the concentration of the acid catalyst is 0.1-1 mol/L;
(e) the pH value is adjusted to 3.0-4.5.
Preferably, step (2) includes any one or a combination of the following features:
(a) the alkali catalyst is one of ammonia water, sodium carbonate, sodium bicarbonate, sodium hydroxide or potassium carbonate;
(b) the concentration of the alkali catalyst is 0.1-5 mol/L;
(c) adjusting the pH value to 7-8.
(d) The molar ratio of the first silicon source to the second silicon source is 0.1-4.
Preferably, step (3) includes any one or a combination of the following features:
(a) the emulsifier is one or more selected from n-hexane, polydimethylsiloxane, soybean oil, span 60 and span 80;
(b) the stirring speed is 500 r/min-1000 r/min.
Preferably, step (4) includes any one or combination of the following features:
(a) the solvent used for aging is one or more of ethanol, n-hexane, tert-butanol, methanol or n-heptane;
(b) the aging times are 1-4 times, and the aging time is 2-8 h.
Preferably, in the step (1), a proper amount of the first silicon source or the second silicon source is taken, the solvent and the water are added, the acid catalyst is added after stirring, the pH value is adjusted, and the first precursor hydrolysate or the second precursor hydrolysate is obtained after hydrolysis.
Preferably, in step (1), a surfactant is further added to the first silicon source and/or the second silicon source.
Preferably, in the step (3), the stirring speed is controlled to control the particle size of the silica aerogel microspheres finally obtained.
Preferably, in the step (5), the drying is normal pressure; the drying temperature is controlled to be 60-120 ℃, and the drying time is 6-48 h.
Preferably, the hydrolysis in the step (1), the step (3) and the aging in the step (4) are all carried out in a constant-temperature water bath at 45 ℃.
In a third aspect, the invention provides the use of the silica aerogel microspheres of the first aspect for adsorbing cigarette side stream smoke and carrying flavors and fragrances.
Preferably, the silica aerogel microspheres are used in cigarette filter rods.
The technical scheme can be freely combined on the premise of no contradiction.
The invention has the following beneficial effects:
(1) the method utilizes a co-precursor method to carefully select two silicon sources, omits the process of surface hydrophobic modification, greatly reduces the use of organic solvents and shortens the preparation period, the obtained aerogel microspheres have full particles, smooth surfaces and slightly static electricity, the microspheres are soft and light, the microsphere material has hydrophobicity, the particle size is 250-1000 mu m, and the density is 0.05-0.20 g/cm3The specific surface area is 400-1000 m2/g。
(2) According to the invention, the silicon dioxide aerogel is made into a small ball shape by an emulsion balling method, the balance weight is added, the problems of light weight and easy dispersion of aerogel powder are solved, and the application field of aerogel materials is increased.
(3) The existing sol-gel preparation process needs to carry out the steps of aging and solvent exchange in an alcoholic solution so as to replace ethanol in gel pores. Before the mixed sol does not have an initial gel state, the mixed sol is transferred into an emulsifier and stirred to form a white wet gel ball. Namely, the process of forming sol into gel is carried out in the emulsifier, the emulsifier is in the pores of the obtained gel, the subsequent solvent exchange process is not needed, and the specific surface area of the finally obtained microspheres is larger and is 400-1000 m2A lower density of 0.05 to 0.20g/cm3。
(4) The invention adopts a normal pressure drying method, and is safer and more environment-friendly compared with supercritical drying.
(5) The aerogel microspheres prepared by the invention have good hydrophobicity and balling property and excellent adsorption performance, can be applied to cigarette filter sticks for adsorbing side-stream smoke of cigarettes and loading essence perfume, and can also be applied to more fields with special requirements such as sewage treatment, chromatographic packing and the like.
Drawings
FIG. 1 is a flow chart of the preparation of silica aerogel microspheres according to example 1 of the present invention.
Fig. 2 is a photograph of an aerogel microsphere prepared according to example 1 of the present invention.
FIG. 3 is a hydrophobicity experiment of aerogel microspheres prepared in example 1 of the present invention.
Fig. 4 is a field emission Scanning Electron Microscope (SEM) image of aerogel microspheres prepared in example 2 of the present invention.
FIG. 5 is a Transmission Electron Micrograph (TEM) of aerogel microspheres prepared according to example 2 of the present invention.
FIG. 6 is a graph of isothermal nitrogen adsorption and desorption curves of aerogel microspheres prepared in example 3 of the present invention, wherein the abscissa is relative pressure (p/p)0) The ordinate is the volume adsorption (cm)3/gSTP)。
FIG. 7 is a Fourier infrared spectrum of an aerogel sample prepared according to example 4 of the present invention.
FIG. 8 is a graph showing the distribution of particle sizes of aerogel samples prepared in example 2 of the present invention.
Detailed Description
The present invention will be further described with reference to the following embodiments.
Example 1
1) 5mL of methyltrimethoxysilane (MTMS), 25mL of deionized water and 0.1g of Cetyl Trimethyl Ammonium Bromide (CTAB) serving as a surfactant are mixed and stirred for 10 minutes by magnetic force, 300 mu L of 0.1mol/L hydrochloric acid solution is added, and the mixture is fully hydrolyzed to obtain a first precursor hydrolysate A.
2) 60mL of industrial water glass with the modulus of 3.5 and the mass concentration of 34% and 60mL of deionized water are mixed and stirred uniformly (the volume ratio is 1:1), and after the industrial water glass and the deionized water are mixed and stirred magnetically for 15 minutes, the mixture is fully exchanged by a sodium type 732 cation exchange resin to obtain a second precursor hydrolysate B.
3) 20mL of the solution B is added into the solution A, and after the solution B is fully stirred for 5 minutes, 0.5mol/L ammonia water is slowly dripped into the solution B to adjust the pH value of the solution to about 8.
4) Before the mixed sol did not appear to be in the initial gel state, it was transferred to n-hexane (source: national pharmaceutical group chemical reagent Co., Ltd.) was mechanically stirred to form wet gel white beads at a stirring speed of 700 r/min.
5) Standing and aging the wet gel for 30min at 45 ℃, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the solid pellets into a drying oven, and drying for 8 hours at the temperature of 80 ℃ to obtain the silicon dioxide aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample was measured by a tap densitometer to be 0.094g/cm3And is hydrophobic, and the particle size distribution measured by a particle size tester is mainly concentrated on 250-1000 μm, wherein 90 percent of the particles have the particle size of 634.8 μm. The specific surface area was measured by a Micromeritics instrument in USA by using BJH principle to obtain 602.4m2/g。
FIG. 1 is a flow chart of the preparation of silica aerogel microspheres according to example 1 of the present invention. Fig. 2 is a photograph of an aerogel microsphere prepared according to example 1 of the present invention. Fig. 3 is a hydrophobicity test of the aerogel microspheres prepared in example 1 of the present invention, and fig. 3 shows that the aerogel microspheres float on the water surface and are not wetted by water, thus showing hydrophobicity.
Example 2
1) Mixing and stirring 10mL of MTMS, 25mL of deionized water and 0.1g of CTAB for 10 minutes, adding 300 mu L of 0.1mol/L hydrochloric acid solution, and fully hydrolyzing to obtain precursor hydrolysate A.
2) 60mL of industrial water glass with the modulus of 3.5 and the mass concentration of 34 percent is mixed and stirred uniformly with 60mL of deionized water (the volume ratio is 1:1), and after the industrial water glass and the deionized water are mixed and stirred for 15 minutes, the mixture is fully exchanged by a sodium type 732 cation exchange resin to obtain precursor hydrolysate B.
3) 20mL of the solution B is added into the solution A, and after the solution B is fully stirred for 5 minutes, 0.5mol/L ammonia water is slowly dripped into the solution B to adjust the pH value of the solution to about 8.
4) Before the initial gel state of the mixed sol does not appear, the mixed sol is transferred into n-hexane (national drug group chemical reagent Co., Ltd.) to be mechanically stirred to form white balls, namely wet gel, and the stirring speed is 700 r/min.
5) Standing and aging the wet gel for 30min at 45 ℃, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the filtered and separated sample into a drying oven, and drying for 8 hours at the temperature of 80 ℃ to obtain the silica aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample was measured by a tap densitometer to be 0.087g/cm3Is hydrophobic, and the particle size distribution measured by a particle size tester is mainly concentrated on 500-m, 90% of which have a particle size of 694.38 μm, the particle size of the microspheres can be increased by adjusting the concentration of MTMS. Specific surface area 725.7m measured by Micromerics instruments in USA using BJH principle2/g。
Fig. 4 is a field emission Scanning Electron Microscope (SEM) image of aerogel microspheres prepared in example 2 of the present invention.
FIG. 5 is a Transmission Electron Micrograph (TEM) of aerogel microspheres prepared according to example 2 of the present invention.
FIG. 8 is a graph showing the distribution of particle sizes of aerogel samples prepared in example 2 of the present invention.
Example 3
1) Mixing and stirring 10mL of MTMS, 25mL of deionized water and 0.1g of Cetyl Trimethyl Ammonium Bromide (CTAB) for 10 minutes, adding 300 mu L of 0.1mol/L hydrochloric acid solution, and fully hydrolyzing to obtain precursor hydrolysate A.
2) Adding 57.5mL of Tetraethoxysilane (TEOS) into 120mL of ethanol, adding 10mL of deionized water during rapid stirring, continuously stirring and adding 0.1mol/L of hydrochloric acid, adjusting the pH value of the solution to be about 3.0, and adjusting the molar ratio of TEOS, ethanol and deionized water to be 1: 8: 2 preparing precursor hydrolysate B.
3) Adding 30mL of the solution B into the solution A, fully stirring for 5 minutes, slowly dropwise adding 0.5mol/L ammonia water, and adjusting the pH value of the solution to about 8.
4) Before the initial gel state of the mixed sol does not appear, the mixed sol is transferred into n-hexane (national drug group chemical reagent Co., Ltd.) to be mechanically stirred to form wet gel white balls, and the stirring speed is 800 r/min.
5) Standing and aging the wet gel for 30min at 45 ℃, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the filtered and separated sample into a drying oven for grading drying, and drying at 80 ℃ and 100 ℃ for 10 hours to obtain the silica aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample was measured by a tap densitometer to be 0.104g/cm3And the particle size distribution is mainly concentrated on 420-1000 mu m measured by a particle size tester, wherein 90 percent of the particle sizes are 838.68 mu m. The ratio was measured by Micromeritics instrument in USA using BJH principleSurface area 557.4m2/g。
FIG. 6 is a graph of isothermal nitrogen adsorption and desorption curves of aerogel microspheres prepared in example 3 of the present invention, wherein the abscissa is relative pressure (p/p)0) The ordinate is the volume adsorption (cm)3/gsttp). It can be seen from the figure that the prepared microspheres have a typical aerogel structure.
Example 4
1) Mixing and stirring 10mL of MTMS, 25mL of deionized water and 0.1g of CTAB for 10 minutes, adding 300 mu L of 0.1mol/L hydrochloric acid solution, and fully hydrolyzing to obtain precursor hydrolysate A.
2) Adding 57.5mL of TEOS into 150mL of ethanol, adding 10mL of deionized water during rapid stirring, continuously stirring and adding 0.1mol/L of hydrochloric acid, adjusting the pH value of the solution to be about 3.5, wherein the molar ratio of TEOS, ethanol and deionized water is 1: 10: 2 preparing precursor hydrolysate B.
3) Adding 30mL of the solution B into the solution A, fully stirring for 5 minutes, slowly dropwise adding 0.5mol/L ammonia water, and adjusting the pH value of the solution to about 8.
4) Before the initial gel state of the mixed sol does not appear, the mixed sol is transferred into normal hexane, and white small ball wet gel is formed by mechanical stirring at the stirring speed of 800 r/min.
5) Standing and aging the wet gel at 45 ℃ for 60min, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the filtered and separated sample into a drying oven for grading drying, and drying at 80 ℃ and 100 ℃ for 8 hours respectively to obtain the silica aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample was measured by a tap densitometer to be 0.092g/cm3Is hydrophobic, and the particle size distribution measured by a particle size tester is mainly concentrated on 450-1000 μm, wherein 90 percent of the particles have the particle size of 812.9 μm. Specific surface area 631.6m measured by Micromerics instruments in USA using BJH principle2/g。
FIG. 7 is a Fourier infrared spectrum of an aerogel sample prepared according to example 4 of the present invention.
Example 5
1) Mixing and stirring 10mL of MTMS, 25mL of deionized water and 0.2g of CTAB for 10 minutes, adding 300 mu L of 0.1mol/L hydrochloric acid solution, and fully hydrolyzing to obtain precursor hydrolysate A.
2) Adding 57.5mL of TEOS into 150mL of ethanol, adding 10mL of deionized water during rapid stirring, continuously stirring and adding 0.1mol/L of hydrochloric acid, adjusting the pH value of the solution to be about 3.5, wherein the molar ratio of TEOS, ethanol and deionized water is 1: 10: 2 preparing precursor hydrolysate B.
3) Adding 30mL of the solution B into the solution A, fully stirring for 5 minutes, slowly dropwise adding 0.5mol/L ammonia water, and adjusting the pH value of the solution to about 8.
4) Before the mixed sol does not have an initial gel state, transferring the mixed sol into n-hexane, and mechanically stirring to form a white small ball wet gel, wherein the stirring speed is 1000 r/min.
5) Standing and aging the wet gel at 45 ℃ for 60min, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the filtered and separated sample into a drying oven for grading drying, and drying at 80 ℃ and 100 ℃ for 8 hours respectively to obtain the silica aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample was measured by a tap densitometer to be 0.192g/cm3Is hydrophobic, and the particle size distribution measured by a particle size tester is mainly concentrated on 300-1000 μm, wherein 90 percent of the particles have the particle size of 532.7 μm. Specific surface area 421.5m measured by Micromerics instruments in USA using BJH principle2/g。
Example 6
1) Mixing and stirring 10mL of MTMS, 25mL of deionized water and 0.05g of CTAB for 10 minutes, adding 300 mu L of 0.1mol/L hydrochloric acid solution, and fully hydrolyzing to obtain precursor hydrolysate A.
2) Adding 57.5mL of TEOS into 150mL of ethanol, adding 10mL of deionized water during rapid stirring, continuously stirring and adding 0.1mol/L of hydrochloric acid, adjusting the pH value of the solution to be about 3.5, wherein the molar ratio of TEOS, ethanol and deionized water is 1: 10: 2 preparing precursor hydrolysate B.
3) Adding 30mL of the solution B into the solution A, fully stirring for 5 minutes, slowly dropwise adding 0.5mol/L ammonia water, and adjusting the pH value of the solution to about 8.
4) Before the initial gel state of the mixed sol does not appear, the mixed sol is transferred into normal hexane, and white small ball wet gel is formed by mechanical stirring at the stirring speed of 800 r/min.
5) Standing and aging the wet gel at 45 ℃ for 60min, and then performing suction filtration and separation to obtain solid spheres. And (3) putting the filtered and separated sample into a drying oven for grading drying, and drying at 80 ℃ and 100 ℃ for 8 hours respectively to obtain the silica aerogel microspheres.
Characterization of silica aerogel microsphere samples:
the density of the sample is measured by a tap densitometer to be 0.061g/cm3Is hydrophobic, and the particle size distribution measured by a particle size tester is mainly concentrated on 450-1000 μm, wherein 90% of the particles have a particle size of 712.9 μm. Specific surface area 956.6m measured by Micromerics instruments in USA using BJH principle2/g。
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. The silica aerogel microspheres are characterized by having hydrophobicity, the particle size of the silica aerogel microspheres is 250-1000 mu m, and the density of the silica aerogel microspheres is 0.05-0.20 g/cm3The specific surface area is 400-1000 m2/g。
2. The method for preparing silica aerogel microspheres according to claim 1, comprising the steps of:
(1) respectively adding acid catalysts into the first silicon source and the second silicon source for hydrolysis to obtain a first precursor hydrolysate and a second precursor hydrolysate; wherein the first silicon source is hydrolyzed to generate silicon hydroxyl and does not contain organic groups; the second silicon source at least contains one non-hydrolytic group;
(2) mixing the first precursor hydrolysate and the second precursor hydrolysate in proportion to form mixed sol, adding an alkali catalyst, and adjusting the pH value of the solution;
(3) before the mixed sol obtained in the step (2) does not have an initial gel state, transferring the mixed sol into an emulsifier and stirring to form white wet gel balls;
(4) immersing the wet gel pellets obtained in the step (3) with a solvent, aging, and filtering to obtain solid pellets;
(5) drying the solid pellets obtained in the step (4) to obtain the silicon dioxide aerogel microspheres;
the preparation method of the silica aerogel microspheres does not comprise the steps of solvent exchange and surface modification.
3. The method of claim 2, wherein the second silicon source is an organosiloxane having one or more hydrocarbon groups.
4. The method of claim 2, wherein step (1) includes any one or a combination of the following features:
(a) the first silicon source is selected from tetraethyl orthosilicate, tetramethyl orthosilicate or water glass;
(b) the second silicon source is selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or dimethyldimethoxysilane;
(c) the acid catalyst is one or more of hydrofluoric acid, hydrochloric acid, sulfuric acid, oxalic acid and acetic acid;
(d) the concentration of the acid catalyst is 0.1-1 mol/L;
(e) the pH value is adjusted to 3.0-4.5.
5. The method of claim 2, wherein step (2) includes any one or a combination of the following features:
(a) the alkali catalyst is one of ammonia water, sodium carbonate, sodium bicarbonate, sodium hydroxide or potassium carbonate;
(b) the concentration of the alkali catalyst is 0.1-5 mol/L;
(c) adjusting the pH value to 7-8.
(d) The molar ratio of the first silicon source to the second silicon source is 0.1-4.
6. The method of claim 2, wherein step (3) includes any one or a combination of the following features:
(a) the emulsifier is one or more selected from n-hexane, polydimethylsiloxane, soybean oil, span 60 and span 80;
(b) the stirring speed is 500 r/min-1000 r/min.
7. The method according to claim 1, wherein the step (4) comprises any one or a combination of the following features:
(a) the solvent used for aging is one or more of ethanol, n-hexane, tert-butanol, methanol or n-heptane;
(b) the aging times are 1-4 times, and the aging time is 2-8 h.
8. The preparation method according to claim 2, wherein in the step (3), the stirring speed is controlled to control the particle size of the silica aerogel microspheres finally obtained.
The drying is normal pressure; the drying temperature is controlled to be 60-120 ℃, and the drying time is 6-48 h.
9. The method according to claim 2, wherein the hydrolysis in step (1), the aging in step (3) and the aging in step (4) are all carried out in a constant temperature water bath at 45 ℃.
10. Use of silica aerogel microspheres according to claim 1 for adsorbing cigarette sidestream smoke and flavor-laden flavors.
CN202010271053.2A 2020-04-08 2020-04-08 Silicon dioxide aerogel microsphere and preparation method and application thereof Pending CN111533133A (en)

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