WO2015192731A1

WO2015192731A1 - Silicon-based monobasic or multibasic oxide aerogel material and preparation method therefor

Info

Publication number: WO2015192731A1
Application number: PCT/CN2015/081204
Authority: WO
Inventors: 金承黎
Original assignee: 金承黎
Priority date: 2014-06-18
Filing date: 2015-06-10
Publication date: 2015-12-23

Abstract

Provided are a silicon-based monobasic or multibasic oxide aerogel material and a preparation method therefor. In the preparation method, water glass is used as a silicon source, a water soluble metal salt corresponding to a mixed metal oxide is randomly selected, an acid or alkali is added into the water soluble metal salt, and the system pH value is adjusted to form a salt-containing monobasic or multibasic oxide collosol; the salt-containing monobasic or multibasic oxide collosol is mixed with a water-soluble organic solvent, the mixture is filtered to remove the produced deposit, a salt-free monobasic or multibasic oxide collosol is obtained, and sol-gel, aging and drying processes are carried out to obtain a monobasic or multibasic oxide aerogel material. The method has low cost and simple process, and facilitates mass production of high efficiency.

Description

Title: A silicon-based mono- or multi-element aerogel material and a preparation method thereof

[0001] The invention relates to an aerogel material and a preparation method thereof, and in particular to a silicon-based mono- or multi-element aerogel material and a preparation method thereof.

Background technique

[0002] Aerogel is a new type of nano-insulation material. It was invented by Kistler.S. in the United States in 1931. It is also called "blue smoke" and "frozen smoke". It has the aggregation of nano-sized ultrafine particles. Nanoporous network structure, porosity up to 80~99.8%, density can be as low as 0.003g/cm ³

The room temperature thermal conductivity can be as low as 0.013w / (nvk), the use temperature can reach 1300 ° C has become a magical material to change the world, 歹 U is one of the top 10 science and technology since the 1990s.

[0003] The so-called silicon-based one-element aerogel, namely silica aerogel, referred to as silicon aerogel, silicon-based multi-oxide aerogel is in-situ composite preparation of silicon dioxide and various other metal oxides Multicomponent oxide aerogel.

[0004] At present, the aerogel materials sold on the market are mainly silicon aerogels, and the use of tetraethyl orthosilicate as the silicon source. Although the process is mature and the quality is good, the high price of the silicone seriously affects the coagulation. Application and promotion of rubber materials.

[0005] The water glass silicon source can reduce the cost of the silicon source significantly because the raw material is easy to be cheap, but the water glass contains impurities such as sodium ions and is difficult to remove. How to remove sodium ions and various types in the process of preparing the aerogel material for the water glass silicon source Impurities, the researchers carried out a lot of bursting work.

[0006] Patent CN1087271C (DE19541715.1) discloses a method for preparing an organic modified aerogel capable of precipitating a formed salt, wherein the method for removing salt from water glass is to react water glass with an acid to form a The acidic silica sol of the salt is then cooled to 0 to 30 ° C, particularly preferably 0 to 5 ° C, and then precipitated from the silica sol due to a decrease in the solubility of the salt in the aqueous solution at a low temperature. The precipitate was then separated using a filtration device.

[0007] Patent CN1126591C discloses a method for organically modifying an aerogel, and the method for removing salt in water glass is firstly, the water glass solution is under the action of an acidic ion exchange resin, a mineral acid or a hydrochloric acid solution. The pH was adjusted to pH < 3, and the obtained silicic acid was polycondensed by adding a base to form a silica aerogel. The gel is then washed with water to free all of the electrolyte therein.

[0008] Patent CN200710175741.3 discloses a method for preparing SiO ₂ aerogel microspheres at low cost, and the method for removing salt in water glass is to dilute according to the volume ratio of water to water glass of 35~3:1. Then, it is added to a sodium type strong acid type styrene cation exchange resin and stirred for 10 minutes, and then washed to neutrality by deionized water or distilled water.

[0009] Patent CN200880010090.5 discloses a method for preparing a hydrophobic aerogel and a hydrophobic aerogel prepared therefrom, which removes salt in water glass by adding water glass to hydrochloric acid 1 at room temperature until The pH of the solution was adjusted to 3 to 4; the solution was placed under acidic conditions of pH 4 to 6 by adding a nonionic surfactant and water glass to form a silica gel, and then the formed silicon gel was washed with distilled water.

[0010] Patent CN201110107204.1 discloses a method for preparing a silica aerogel, which removes salt from water glass by adding water glass to hydrochloric acid for reaction until the pH of the solution is adjusted to 3 ~ 4, forming a silica hydrogel; placing the silica hydrogel in a container in which water is placed, the two ends of the container are respectively connected to the positive and negative electrodes and electrified to remove salt.

[0011] Silicon aerogels have been initially mass-produced, but other types of oxide aerogels, such as alumina aerogels, zirconia aerogels, titanium oxide aerogels, etc., are still at experimental levels. The preparation of vanadium oxide aerogel and cerium oxide aerogel is more difficult, and the distance from large-scale industrial production is farther away.

[0012] Patent CN200810033022.2 discloses a transition metal based aerogel, transition metal oxide aerogel

, a method for preparing a composite transition metal oxide aerogel, using a transition metal chloride as a precursor, a polyacrylic acid as a dispersant, and propylene oxide as a gel promoter, through a sol-gel process, combined with supercritical drying and heat treatment Process, a variety of periodic, multi-family transition metal-based aerogels and transition metal oxide aerogel materials were prepared. As a general preparation method, the invention has the characteristics that the raw materials are cheap and easy to obtain, the reaction process is simple, the reaction cycle is short, and the like, and the problem that many transition metal oxide aerogels are difficult to prepare is solved.

[0013] Although the above patents have achieved breakthroughs in the preparation of transition metal oxide aerogels at the laboratory level, they still face difficulties in achieving industrial production. To this end, the researchers began to use the preparation process of relatively mature silica aerogel to prepare binary or multi-component aerogels by compounding other oxide components. [0014] Patent CN201210038638.5 discloses a one- or multi-component aerogel insulation material and a preparation method thereof, and prepares a silica sol by hydrolysis of ethyl orthosilicate, and adds water, ethanol and epoxy to an inorganic aluminum salt such as aluminum nitrate. An aluminum sol is prepared by propane or the like, a silica sol is added to the alumina sol, mixed and stirred, and an opacifier titanium dioxide is added to obtain a silica alumina composite sol of a sunscreen.

[0015] Patent CN201310139544.1 discloses a preparation method of a zirconia-silica composite aerogel, dissolving siloxane in alcohol, adding zirconium alkoxide dropwise, stirring uniformly, adding deionized water to obtain clear and transparent The sol is transferred to a mold and allowed to stand to form a zirconia-silica composite wet gel; the wet gel is immersed in an aging solution; and finally immersed in an anhydrous ethanol or isopropanol solvent. The invention prepares a low-density, low thermal conductivity bulk zirconia-silica composite aerogel, which still maintains the original microscopic morphology after heat treatment at 1000 ° C, and is still an amorphous structure, and has a specific surface area of up to 353 m 2 . /g, with good high temperature stability.

[0016] Patent CN201310498274.3 discloses a method for preparing an insulated alumina-silica-zirconium oxide ternary composite aerogel, which comprises an inorganic aluminum salt, a silicon salt, an inorganic zirconium salt as a precursor, an alcohol solvent It is dissolved in water and reacted with ij. The epoxide is a gel accelerator. After the supercritical fluid drying process, a bulk ternary aerogel with excellent properties is obtained. The obtained ternary aerogel sample has lower density, better elasticity and stable performance, and can withstand higher temperature and more stable quality than different unit alumina, silica and zirconia aerogels. Excellent high temperature stability extends the range of aerogels to allow them to be used in the field of heat insulation.

[0017] Patent CN201410026654.1 discloses a preparation method of a titanium-doped silicon-based composite aerogel, which uses potassium titanate as a titanium source, and has excellent production performance by ion exchange, sol-gel method and atmospheric pressure drying. Titanium miscellaneous silicon-based composite aerogel materials, mainly including (1) ion exchange process of titanate and sol-gel process of tetraethyl orthosilicate; (2) preparation of titanium miscible silicon-based wet gel; (3) modification of titanium miscellaneous silicon-based wet gel;

(4) Normal pressure drying of titanium miscellaneous silicon-based aerogels. The method has the advantages of simple process, low cost and easy scale production, and the obtained titanium miscellaneous silicon-based aerogel photocatalyst has the characteristics of nano structure, large specific surface area, high hole ratio and firm structure, and has hydrophobic property and can be used for air. It is suitable for large-scale environmental pollution treatment in the fields of purification, sewage treatment, etc., and is easy to separate and recycle.

[0018] Patent CN201210067184.4 discloses a preparation method of a multi-element aerogel, the main method is to manufacture Based on the preparation method of silica aerogel, a compound containing phosphorus, tin, zinc and the like and a gelling agent are added to connect phosphorus, tin, zinc and the like with oxygen as a bridge to the structure of silicon oxide to form a high specific surface area. The SiO2-P205/Sn02/ZnO multi-aerogel porous composite with low density and average pore diameter (l-50nm) can be widely used in filtration materials, thermal barrier coating materials, optical and gas measurement.

technical problem

[0019] The above-mentioned public water glass silicon source for preparing aerogel materials, there are four methods for removing salt and impurities in water glass, and the publication and implementation of these patents will facilitate the water glass silicon source silicon base. The advancement of a single oxide aerogel material bursts, but there are still many problems: 1) Low temperature crystallization. The method requires cooling and cooling of the sol, and the energy consumption is large. At the same time, the salt does not ensure the complete precipitation of the salt. Even at o °c, the solubility of sodium sulfate in water is 4.9 g/100 g of water; 2) ion exchange method . A strong acid cation exchange resin is used to remove metal ions such as sodium ions in the water glass. Limited capacity due to cation exchange resin

(Generally 5mmol/g), the test level is acceptable. If it is industrialized, the high concentration of sodium ions in water glass (content 7.5~12.8% wt) will lead to rapid saturation of ion exchange resin exchange capacity. Production; 3) Wash with deionized water or distilled water. This method removes the salt in the gel by continuously diluting it by washing with water after gel formation. Industrial production can be realized. The disadvantages are large water consumption, long consumption, and large amount of brine treated. 4) Deionization of the electrode. This method also performs the desalination of the positive and negative electrodes by the characteristics of the salt electrolyte after the gel is formed. The difficulty faced by this method is similar to the electrode method desalination, and it is difficult to find a large-capacity inexpensive electrode.

[0020] The above-mentioned patents and implementations of in-situ composite preparation of binary or multi-component aerogel materials using a silicon aerogel process will facilitate the advancement of high-quality multi-aerogel materials, but still have the following problems: The silicon source used in the existing binary or multi-component aerogel preparation technology is basically an organosilicon ester such as tetraethyl orthosilicate, and the price of the organosilicon ester is high, which restricts the production cost of the aerogel; 2) the prior art The reaction environment is basically an alcohol-containing system. Since most metal salts are insoluble in ethanol, direct addition will produce precipitation, which severely restricts the available types and addition effects of metal salts, and it is difficult to achieve ideal in-situ recombination; The technology mainly focuses on the binary or ternary compounding of silicon oxide with titanium oxide, aluminum oxide and zirconium oxide. The metal oxides involved are of a small variety and cannot be a general preparation method for multi-element aerogels. 4) Existing Technology For the smooth gelation of added metal oxides, propylene oxide, a flammable and explosive toxic substance, which is irritating to mucous membranes and skin, can damage the cornea. Conjunctiva, respiratory system, causing pain, skin burning Injury and swelling, and even tissue necrosis.

[0021] In view of the deficiencies of existing techniques for preparing silicon-based mono- and multi-aerogel materials, the present invention proposes novel silicon-based mono- or multi-element aerogel materials and methods for their preparation.

Problem solution

Technical solution

[0022] A silicon-based mono- and multi-element aerogel material and a preparation method thereof, comprising the following steps: (1) a water-soluble metal salt corresponding to a metal oxide of water glass or water glass Mixing, adjusting the pH with an acid or a base to obtain a salt-containing mono- or multi-element oxide sol;

[0024] the water glass comprises one or more of sodium silicate, potassium silicate, lithium silicate;

[0025] The metal oxide is a poorly water-soluble metal oxide of the formula MxOy, wherein M represents a metal atom, 0 represents an atom, and X and y represent the corresponding atomic number in the molecular formula, respectively;

The metal oxide includes aluminum oxide, zirconium oxide, titanium oxide, iron oxide, tungsten oxide, vanadium oxide, antimony oxide, magnesium oxide, copper oxide, indium oxide, gallium oxide, tin oxide, antimony oxide, oxidation. a kind of manganese, cobalt oxide, nickel oxide, zinc oxide, cadmium oxide, chromium oxide, tungsten oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide or cerium oxide. Or several

[0027] the water-soluble metal salt includes an acidic, basic or neutral soluble metal corresponding to the above metal oxide

[0028] the water-soluble metal salt comprises the above-mentioned metal oxide and the corresponding hydroxide, metal or sodium oxide, potassium oxide one or more of the reaction of the formation of alkaline or neutral water-soluble salts;

[0029] The water-soluble metal salt includes the above metal oxide and corresponding hydroxide, metal and hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, iodic acid, oxalic acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrogen Fluoric acid, sulfurous acid

a reaction in nitrous acid to form an acidic or neutral water-soluble salt;

[0030] The water glass and the water-soluble metal salt mixture may be directly mixed with the water glass and the water-soluble metal salt, or the water glass and the water-soluble metal salt may be separately diluted and mixed;

[0031] The water glass is mixed with the water-soluble metal salt, and the water glass and the soluble metal salt may be first dissolved in the acid and then mixed, or the water glass and the soluble metal salt may be dissolved in the alkali and then mixed, or may be water. The glass and the soluble metal salt are respectively dissolved in an acid or a base and mixed, and the water glass may be mixed with the soluble metal salt and then dissolved in the acid or the alkali; [0032] The water glass and the water-soluble metal salt mixture, the water glass and the water-soluble metal salt volume ratio is 1:0.01~10 0, preferably 1:0.1~10.

[0033] The pH-adjusting acid is one or more of an inorganic acid or an organic acid; the inorganic acid includes an oxo acid, an oxo acid, a complex acid, preferably sulfuric acid, phosphoric acid and hydrochloric acid; and the organic acid includes a carboxylic acid ( -COOH), sulfonic acid (-S03H), sulfinic acid (RSOOH), sulfuric acid (RCOSH), preferably oxalic acid, acetic acid, formic acid, propionic acid, n-butyric acid, orthovaleric acid.

[0034] The pH adjusting base includes sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, potassium hydrogencarbonate And one or more of ammonia water;

[0035] The pH of the salt-containing mono- or multi-element oxide sol is 0.1 to 4.0, preferably 1.5 to 3.5;

[0036] (2) mixing the multi-element sol with a water-soluble organic solvent to remove precipitates to obtain a salt-free multi-element oxide sol;

[0037] The organic solvent is one or more of an alcohol, an ether, an ester, a ketone, an aldehyde, an aliphatic or an aromatic hydrocarbon, and preferably has a carbon number of less than 8, and particularly preferably methanol, ethanol, and B. Glycol, propanol, glycerol, propenol, acetone, formaldehyde, acetaldehyde, propionaldehyde.

[0038] The generated precipitate is removed by filtration, including centrifugal filtration, vacuum filtration, and pressure filtration.

[0039] (3) finely adjusting the pH of the above acidic silica sol with an acid or a base, directly standing or immersed in the reinforcing fiber to form a gel, aging;

[0040] the pH value is 3.0~7.0;

[0041] the fiber comprises one or more of the fiber including inorganic fiber and organic fiber, and a felt, a plate and a cloth made of the above fiber;

[0042] the organic fiber comprises polyester, nylon, spandex, acrylic, aramid, polyamide fiber, polyacrylonitrile pre-oxidized fiber, Kevlar fiber, cellulose fiber, carbon fiber;

[0043] The inorganic fibers include quartz fibers, high silica fibers, aluminum silicate fibers, glass fibers, mullite fibers, silicon carbide fibers, silicon nitride fibers, alumina fibers, boron nitride fibers, basalt fibers, Brucite fiber, attapulgite fiber;

[0044] (4) drying the gel to obtain an aerogel material, the drying method comprises supercritical drying or atmospheric drying or microwave vacuum drying; [0045] the supercritical drying, the drying medium comprises ethanol or carbon dioxide;

[0046] The atmospheric drying, including hot air drying and infrared drying, the drying medium of hot air drying is air, nitrogen or carbon dioxide, preferably nitrogen and carbon dioxide;

[0047] The microwave vacuum drying, the vacuum of the equipment before drying should be less than 100 Torr, preferably less than 10 Torr.

[0048] The atmospheric pressure drying and microwave vacuum drying, the hydrophobic agent is required to be hydrophobically modified with a hydrophobic agent before drying; supercritical drying, hydrophobization modification before drying, or hydrophobization modification.

[0049] The gel hydrophobic agent is a silicone water repellent having a silicon methyl structure, including hexamethyldisilazane

, hexamethyldisiloxane, methyltrimethylsilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, Trimethyl methoxy silane and trimethyl chloro silane;

[0050] The technical principle of the present invention includes two aspects: one is rapid salt removal of a salt-containing mono- or multi-element oxide sol; second, a silica sol and other metal oxide sols are co-gel in situ to form a multi-element nano-particle porous structure.

[0051] First, a sodium carbonate glass (sodium silicate) and sulfuric acid are mixed as an example to illustrate the mechanism of salt removal by a water-soluble organic solvent on a monobasic salt-containing silica sol. The main component of sodium water glass is sodium silicate. When sodium silicate and sulfuric acid are mixed, nano-sized hydrated silica, that is, silica sol, is formed, and a large amount of sodium sulfate is formed. Sodium silicate is a soluble salt in water. Its solubility in water at 20 ° C is 19.5 g / 100 g of water, but it is almost insoluble in organic solvents such as ethanol. When the content of ethanol in the silica sol reaches 5% or more, there is a large amount of sulfate. The crystals precipitated and the ethanol concentration reached 70%, and even sodium sulfate having a content of 200 ppm precipitated. Thus, the salt of the silica sol can be analyzed by an organic solvent such as ethanol, and the precipitate can be removed by filtration to achieve the purpose of removing salt impurities. The desalination mechanism of the multi-element sol is consistent with the desalination of the above water glass. When the water glass and the aqueous metal salt are mixed, the salt-containing multi-oxide sol containing nano-silica and other nano-metal oxides is formed by adjusting the pH value. And the water-soluble salt, the water-soluble organic solvent is added, the salt in the sol rapidly forms a precipitate to be removed, the pH is adjusted again, and the multi-oxide sol forms a gel.

[0052] The mechanism of in situ cogelation of a multi-element oxide sol is explained below. The preparation of non-silicon oxide aerogels has long been difficult. At present, a common method is to promote gelation by adding propylene oxide, and then drying by solvent replacement, surface modification, atmospheric pressure or supercritical. Although this method can produce a wide variety of non-silicon oxide aerogels, they all stay at the laboratory level, and there is no report on mass production. Road. The invention utilizes the mature production process of the existing silica aerogel, and mixes the water glass with various soluble metal salts to form a multi-element sol which is uniformly mixed at the molecular level, and after the salt removal, the silica sol is in the gel formation process. It acts as a templating agent, so that a large number of metal oxide aerogels which are not easily prepared as aerogel alone can easily form a gel structure.

[0053] The implementation of the present invention can achieve the two purposes. First, the silicon-based mono- and multi-component aerogels can be prepared in batches to promote the preparation and industrialization of different kinds of oxide aerogels; In-situ composites of other metal oxides can significantly improve their performance, giving silica aerogel more excellent performance in terms of sound, light, electricity, magnetism and heat. For example, silica aerogel composite alumina, titanium oxide, zirconium oxide, cerium oxide and other aerogels can significantly improve the thermal insulation properties and thermal stability at high temperatures; composite iron oxide, cobalt oxide, nickel oxide, cerium oxide, Aerogels such as cerium oxide can obtain magnetic properties; composite aerogels such as vanadium oxide, titanium oxide, cerium oxide, and cerium oxide can improve catalytic performance; aerogels such as manganese oxide and zinc oxide can be used as battery electrodes; Rare earth oxide aerogels such as cerium oxide, cerium oxide, cerium oxide, etc. can be used as luminescent materials; aerogels such as gallium oxide, cerium oxide, tin oxide, indium oxide, etc. can be used as a semiconductor or exhibit piezoelectricity; composite zinc oxide, oxidation Aerogels such as cadmium and tin oxide can be used as gas sensors and the like.

[0054] The preparation method of the mono- or multi-element aerogel proposed by the invention uses the cheapest water glass for the silicon source, and the cheaper inorganic metal salt for the other soluble metal salt instead of the traditional expensive and toxic organic Metal salt, with easy availability of raw materials, low cost of production, safe and reliable.

[0055] The water glass and the water-soluble metal salt are mixed in the water system, can avoid interference of organic substances such as alcohol, realize co-solubilization in the form of nano-sized metal oxides, have high dispersibility, controllable particle size, and wide application range. A method for preparing a universal multi-oxide aerogel.

The salt-containing monobasic or multi-element oxide sol of the present invention is preferably an acidic system, so that the organic solvent may be prevented from causing the mono- or multi-element oxide sol to gel rapidly and not to precipitate a salt. The pH of the mono- or multi-element oxide sol is controlled from 0.1 to 4.0 in order to obtain a mono- or multi-element oxide sol which can be stored for a long period of time for subsequent filtration and desalination work. The pH value is preferably 1.5~3.5 in order to adjust the pH value to promote the gel. Minimize the introduction of alkali and avoid new impurities to affect the product quality.

[0057] In the present invention, a mono- or multi-element oxide sol is combined with a fiber material to obtain an aerogel composite material of various forms and uses. [0058] The atmospheric pressure drying of the present invention uses a hot air drying medium, preferably a nitrogen or carbon dioxide inert medium, in order to avoid contact of the organic solvent in the aerogel with oxygen, and improve safety; The drying efficiency, together with the vacuum combination, can avoid the safety hazard caused by the spark in the container due to the tip discharge effect, and the drying efficiency under vacuum is further improved.

Advantageous effects of the invention

Beneficial effect

The silicon-based mono- or multi-element aerogel material prepared by the present invention has the following significant advantages over the prior art.

[0060] (1) The use of most of the salts are insoluble in the organic solvent, removing the sodium or potassium ions contained in the water glass silicon source or the water-soluble metal salt, is a simple process, efficient and thorough removal of impurities It is especially suitable for the preparation of high quality aerogels from cheap inorganic salts.

[0061] (2) The organic solvent is introduced in the sol phase, which can eliminate the solvent replacement step of the conventional water glass silicon source process after deionization, saves the daytime, and also greatly reduces the amount of replacement solvent and reduces the cost.

[0062] (3) The invention adopts a silicon-based in-situ composite multi-oxide aerogel, and can prepare a plurality of oxide aerogels which are difficult to prepare, and realize multi-component dispersion at a nanometer scale, which is a kind of The preparation method of the suitable multi-oxide aerogel will promote the development of preparation technology of different kinds of oxide aerogels.

[0063] (4) The invention can significantly improve the performance of the silica sol after in-situ compounding other metal oxides, and imparts the silica aerogel to the sound, light, electricity, magnetism, heat, etc. The excellent performance and greatly widened the range of aerogel applications. The products are widely used in high temperature insulation, sound insulation, catalyst and catalytic carrier, battery electrode, electromagnetic, electrical resistance, gas sensitivity, humidity sensitive, luminescent materials and other fields.

BEST MODE FOR CARRYING OUT THE INVENTION

BEST MODE 1

[0065] 80 g of sodium water glass (sodium silicate) having a modulus of 3.3 was weighed, and 60 g of pure water was added and stirred to obtain a diluted water glass. 20 g of sulfuric acid having a concentration of 40% by weight was weighed, and then the diluted water glass was added to the sulfuric acid with stirring until the pH was 3. Continue to add 300 g of 95% by weight of ethanol with stirring. The precipitate in the sol was removed by a centrifugal filter to obtain a transparent clear silica sol. Adding 1%wt of ammonia water to the silica sol to adjust the pH After 4.1 minutes, the gel was gelled and allowed to stand at room temperature for 5 h. The aged gel was placed in 500 ml of a mixture of 40% by weight of sulfuric acid and 95% ethanol having a mass ratio of 2:8 and soaked for 3 hours at room temperature for acidification. The acidified gel was placed in 500 ml of hexamethyldisilazane and hydrophobized at room temperature. After 6 hours, the modification was completed, and the gel was subjected to supercritical drying for 10 hours. The drying medium was carbon dioxide, the temperature was 55 ° C, and the pressure was 12 MPa. A silicon-based one-element aerogel translucent particle having a density of 62 kg/m 3 and a specific surface area of 780 m 2 /g was obtained.

BEST MODE 2

[0067] 80 g of potassium water glass (potassium silicate) having a modulus of 2.4 was weighed, and 10 g of pure water was added and stirred to obtain a diluted water glass solution 1. 20 g of hydrochloric acid having a concentration of 10% by weight was weighed, and then the diluted water glass was added to hydrochloric acid with stirring until the pH was 3 to obtain a solution 2. 20 g of ferric chloride, 12 g of cobalt chloride, and 2 g of ruthenium chloride were weighed and dissolved in 100 g of pure water to obtain a solution 3. The solution 3 was mixed with the solution 2, and 1% potassium hydroxide was added dropwise to adjust the pH to 3.5 to obtain a salt-containing multi-oxide sol solution 4. The solution 4 was mixed with 400 g of acetone, and the precipitate of potassium chloride in the sol was removed by a centrifugal filter to obtain a multi-element oxide sol solution 5. To the solution 5, a concentration of 1% by weight of aqueous ammonia was added dropwise, the pH was adjusted to 4.5, and the mixture was poured into a box covered with a high-silicone needle felt for 20 minutes, and then gelled and allowed to stand for 15 hours. The aged gel was placed in 500 ml of a mixture of trimethylethoxysilane and hexamethylsilane to be hydrophobized. After 6 hours, the modification was completed, and the gel was vacuum dried at 100 ° C in a vacuum of 1 Torr to obtain a dark brown silica-iron oxide-cobalt oxide-yttria multi-oxide aerogel high silica fiber composite felt. It has a density of 275 kg/m ³ and a specific surface area of 580 m ² /g.

Embodiments of the invention

Embodiment 1

[0069] 80 g of sodium water glass having a modulus of 3.6 was weighed, and 80 g of pure water was added and stirred to obtain a diluted water glass. 25 g of phosphoric acid having a concentration of 30% by weight was weighed, and then diluted water glass was added to the phosphoric acid with stirring until the pH was 2.3. Continue to add 300 g of 95% by weight of methanol with stirring. The precipitate in the sol was removed by a vacuum filter to obtain a transparent clear silica sol. To the silica sol, a concentration of 1% by weight of sodium hydroxide was added dropwise, and the pH was adjusted to 4.3. After 30 minutes, the gel was gelled and allowed to stand at 40 ° C for 6 hours. The aged gel was placed in 500 ml of a mixture of 40% by weight of sulfuric acid and propanol at a mass ratio of 3:7 for 3 hours at 35 ° C for acidification. The acidified gel was placed in 500 ml of dimethyldiethoxysilane and hydrophobized at 50 °C. After 8 h, the modification was completed, and the gel was subjected to nitrogen hot air drying for 5 hours, and the nitrogen gas temperature was 80 °C. The obtained aerogel is translucent particles with a density of 70kg /m ³ , specific surface area 640 m ² /g.

Example 2

[0071] 80 g of potassium water glass having a modulus of 3.3 was weighed, and 100 g of pure water was added and stirred to obtain a diluted water glass. Weigh 10 g of acetic acid at a concentration of 50% by weight, and then add the diluted water glass to the acetic acid while stirring until the pH is 3. Continue to add 300 g of acetone with stirring. The precipitate in the sol was removed by a pressurized titanium rod filter to obtain a transparent clear silica sol. Add 1% potassium hydroxide to the silica sol, adjust the pH to 3.7, add the titanium dioxide opacifier and stir evenly, pour into the box with the glass fiber needle felt, gel after 90 min, aging at 25 ° C for 7 h . The aged gel was placed in 500 ml of a mixture of 40% oxalic acid and anhydrous ethanol having a mass ratio of 2:8 and soaked at 25 ° C for 3.5 hours for acidification. The acidified gel was placed in 500 ml of hexamethyldisiloxane and hydrophobized at 50 °C. After 7 hours, the modification was completed, and the gel was subjected to microwave vacuum drying, and the microwave vacuum dryer was evacuated to 10 -2 before drying.

Carry the following. Obtained aerogel glass fiber composite felt, density 210kg/m 3

, thermal conductivity 0.018w / m, k, water absorption rate 1.8 <3⁄4.

Example 3

[0073] 80 g of sodium water glass having a modulus of 2.4 was weighed, and 10 g of pure water was added and stirred to obtain a diluted water glass. Weigh 20 g of sulfuric acid having a concentration of 40% by weight, and then add the diluted water glass to the acid while stirring until the pH is 3. Continue to add 400 g of anhydrous acetaldehyde with stirring. The precipitate in the sol was removed by a centrifugal filter to obtain a transparent clarified silica sol. Approximately 2% by weight of ammonia water was added to the silica sol, and the pH was adjusted to 4.5. The mixture was poured into a box covered with a polyester fiber needle cloth for 20 minutes, and then gelled and allowed to stand for 15 hours. Pour 100 ml of the aged gel and soak it in 40% acetic acid for 3 hours for acidification. The acidified gel was placed in 500 ml of trimethylmethoxysilane to be hydrophobized. After 6 hours, the modification was completed, and the gel was subjected to supercritical drying for 10 hours. The drying medium was ethanol, the temperature was 40 ° C, and the pressure was 10 MPa. The aerogel polyester composite felt was obtained, and the density was 180 kg/m, the thermal conductivity was 0.017 w/m, k, and the water absorption rate was 1.2<3⁄4.

Example 4

80 g of sodium water glass having a modulus of 3.3 was weighed, and 160 g of pure water was added and stirred to obtain a diluted water glass. 10 g of oxalic acid having a concentration of 10% by weight and 20 g of sulfuric acid of 40% by weight were weighed, and then the diluted water glass was added to the acid with stirring until the pH was 3. Continue to add 300 g of 95% by weight of ethanol with stirring. The precipitate in the sol was removed by a vacuum filter to obtain a transparent clear silica sol. Adding 2% by weight of hydroxide to the silica sol Sodium, adjust the pH to 4.1, add titanium oxysulfate sunscreen and stir evenly into a box covered with alumina fiber board. After 50 minutes, the gel is gelled and allowed to stand at 90 ° C for 10 h. The aged gel was placed in 500 ml of a 40% by weight mixture of phosphoric acid and propanol at a mass ratio of 1:9 for 3 hours at 70 ° C for acidification. The acidified gel was placed in 500 ml of methyltrimethylsilane, 60. Hydrophobic modification is carried out under C. After 6 hours, the modification was completed, and the gel was dried under an infrared lamp for 5 hours. Obtained aerogel alumina fiber composite board with a density of 350kg/m 3

, thermal conductivity 0.023w/m k, water absorption 1.9<3⁄4.

Example 5

[0077] 80 g of sodium water glass (sodium silicate) having a modulus of 3.3 was weighed, and 60 g of pure water was added and stirred to obtain a diluted water glass solution 1. 20 g of sulfuric acid having a concentration of 40% by weight was weighed, and then the diluted water glass solution 1 was added to sulfuric acid with stirring to obtain an acidified water glass solution 2. 20 g of solid zirconium sulfate powder and 3 g of titanyl sulfate powder were weighed and dissolved in 50 g of pure water to obtain a water-soluble metal salt mixture solution 3. The solution 3 was mixed with the solution 2, and 1% by weight of sodium hydroxide was added dropwise to adjust the pH to 3.2 to obtain a salt-containing multi-oxide sol solution 4. To the solution 4, 350 g of 95% by weight of ethanol was added. The sodium sulfate precipitate in the sol was removed by a centrifugal filter to obtain a multi-element sol. Approximately 1% by weight of aqueous ammonia was added to the multi-oxide sol, the pH was adjusted to 4.0, and the gel was gelled for 65 minutes, and allowed to stand at room temperature for 5 hours. The aged gel was placed in 500 ml of a mixture of 40% by weight of sulfuric acid and 95% ethanol in a mass ratio of 2:8 for 3 hours at room temperature for acidification. The acidified gel was placed in 800 ml of dimethyldimethoxysilane and subjected to hydrophobization modification at room temperature. After 6 hours, the modification was completed, and the gel was dried at a normal pressure of 110 ° C under nitrogen. A white silica-zirconia-titanium oxide composite aerogel having a density of 86 kg/m 3 and a specific surface area of 630 m ² /g was obtained.

Example 6

[0079] 80 g of potassium water glass (potassium silicate) having a modulus of 3.6 was weighed, and 80 g of pure water was added thereto and stirred uniformly to obtain a diluted water glass solution 1. 12 g of solid zinc sulfate powder and 6 g of manganese sulfate were weighed and dissolved in 80 g of pure water to obtain a solution 2. The solution 2 was added dropwise to the solution 1 while stirring, and when the pH was 11 Å, the salt-containing multi-oxide sol solution 3 was obtained. 40% of the solution was mixed with a propanol solution at a mass ratio of 1:10 to obtain 150 ml of an acidic organic solvent 4. The solution 3 was added dropwise to the organic solvent 4 while stirring. When the pH was 3.3 Torr, the dropwise addition was stopped, and the potassium sulfate formed by the filtration was precipitated to obtain a multi-element sol 5, and 1% sodium hydroxide was added dropwise to adjust the pH value 4.1, still. Gel after 50 min. The gel was aged in 500 ml of propanol for 1 day. Continue to add 10 g of dimethyldiethoxysilane to the propanol liquid, 50. Hydrophobic modification is carried out under C. After 8 hours, the modification was completed, and the gel was subjected to supercritical drying of carbon dioxide. Get black gray oxidation Silicon-manganese oxide-zinc oxide multi-oxide aerogel having a density of 75 kg/m 3 and a specific surface area of 610 m 2 /g.

Example 7

[0081] 80 g of lithium water glass (lithium silicate) having a modulus of 3.3, 5 g of gallium hydroxide powder, 4 g of barium hydroxide, 3 g of tin hydroxide, 3% of indium hydroxide, and added to a hydroxide having a mass fraction of 50% The solution was stirred at 65 ° C for 1 h in 200 g of sodium to obtain a solution 1. To the solution 1 was added dropwise to a nitric acid having a mass fraction of 100% until the pH was 8.2, and a salt-containing multi-oxide sol solution 2 was obtained. To solution 2, 0.3 g of BYC-8440 polyether modified polyorganosiloxane solution 3 was added while stirring, and 300 g of ethanol was added to solution 3, and the sodium nitrate precipitate in the sol was removed by a pressurized titanium rod filter to obtain Multi-element oxide sol. Add 5% sulfuric acid to the multi-oxide sol, adjust the pH to 7.5, pour into a box with glass fiber needle felt, gel after 80 min, aging at 25 ° C for 7 h, then carry out supercritical carbon dioxide dry. A pale yellow silica-gallium oxide-yttria-tin oxide-indium oxide multi-oxide aerogel glass fiber composite mat having a density of 230 kg/m3 and a specific surface area of 606 m 2 /g was obtained.

Example 8

80 g of sodium water glass having a modulus of 3.3 was weighed, and 160 g of pure water was added and stirred uniformly to obtain a diluted water glass solution 1.

2 g of cerium chloride powder, lg of cerium chloride powder, lg of cerium chloride powder were weighed and dissolved in 100 g of a sodium hydroxide solution having a mass fraction of 20% to obtain a solution 2. After the solution 1 was mixed with the solution 2, it was added to sulfuric acid having a mass fraction of 20% until the pH was 2.5, and a salt-containing multi-oxide sol solution 3 was obtained. To the solution 3, 300 g of 95% by weight of ethanol was added while stirring. The sodium chloride and sodium sulfate in the sol were removed by a vacuum filter to obtain a multi-element sol. To the multi-oxide sol, a concentration of 1% by weight of sodium hydroxide was added dropwise, and the pH was adjusted to 4.1. After 50 minutes, the gel was gelled and allowed to stand at 90 ° C for 10 h. The aged gel was placed in 500 ml of a mixture of trimethylethoxysilane and ethanolol in a mass ratio of 1:9. Soak for 3 hours under C for hydrophobic modification. After 6 hours, the modification was completed, and the gel was subjected to supercritical drying of ethanol to obtain a light orange silica-yttria-yttria-yttria multi-oxide aerogel having a density of 90 kg/m ³ and a specific surface area of 660 m ² /g.

Industrial applicability

The silicon-based mono- or multi-element aerogel material prepared by the present invention has the following remarkable industrial applicability as compared with the prior art.

[0085] (1) Using the characteristics that most of the salts are insoluble in the organic solvent, the sodium ion or potassium ion contained in the water glass silicon source or the water-soluble metal salt is removed, and the process is simple and efficient, and the device is mature and reliable. The filtered precipitate directly becomes a solid material, which can be disposed of as a solid waste or as an industrial grade chemical raw material. Sold, avoiding the traditional washing and deionization of a large amount of water resources, washing out the salt water to pollute the environment, and then carrying out wastewater treatment, wastewater treatment concentrates need to be evaporated to solids and so on.

[0086] (2) The invention adopts a silicon-based in-situ composite multi-oxide aerogel, which is a universal preparation method of a multi-oxide aerogel, which will vigorously promote the industrial production of a multi-oxide aerogel. And aerogel materials are widely used in sound, light, electricity, magnetism, heat, and the like.

[0087] (3) The silicon-based mono or multi-element aerogel prepared by the invention has the characteristics of easy availability of raw materials, low cost of production, safety and reliability, and is advantageous for industrialized large-scale production.

[0088] (4) The silicon-based mono or multi-element aerogel of the present invention can be subjected to supercritical drying or atmospheric drying or microwave vacuum drying, and the preparation process has strong adaptability to different drying methods.

(5) The silicon-based mono or multi-element aerogel prepared by the present invention has an excellent pore structure, a density of 50 to 360 kg/m ³ and a specific surface area of 500 to 850 m ² /g.

Claims

Claim

[Claim 1] A silicon-based one-element aerogel material and a preparation method thereof, wherein the preparation process of the silicon-based one-element aerogel material comprises the following steps:

1) After diluting the water glass with pure water, adjust the pH value with acid to obtain a salt-containing silica sol;

2) mixing the salt-containing silica sol with a water-soluble organic solvent, and then removing the precipitate formed to obtain a high-purity silica sol;

3) finely adjusting the pH value of the above silica sol with a base, directly standing to form a gel or immersing in the reinforcing fiber to form a gel, and standing still;

4) Dry the gel to obtain an aerogel material, which includes supercritical drying or atmospheric drying or microwave vacuum drying.

[Claim 2] A silicon-based multi-oxide aerogel material and a preparation method thereof, characterized in that the preparation process of the multi-oxide aerogel material comprises the following steps:

1) adjusting the pH value of the water-soluble metal salt mixture corresponding to the water glass and the metal oxide to obtain a salt-containing multi-oxide sol;

2) mixing a multi-element sol with a water-soluble organic solvent to remove a precipitate to obtain a salt-free multi-element sol;

3) finely adjusting the pH value of the above multi-oxide sol with acid or alkali, standing still or immersing in the reinforcing fiber, and then standing to form a gel, and standing and aging;

[Claim 3] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the water glass according to the step (1) contains silicic acid. One or more of sodium, potassium silicate, and lithium silicate.

[Claim 4] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, characterized by the acid of steps (1) and (3) One or more of inorganic or organic acids; inorganic acids including oxyacids, anaerobic acids, complex acids, preferably sulfuric acid, phosphoric acid and hydrochloric acid; organic acids including carboxylic acids (-COOH), sulfonic acids (-S03H , sulfinic acid (R SOOH), sulfuric acid (RCOSH), preferably oxalic acid, acetic acid, formic acid, propionic acid, n-butyl Acid, n-valeric acid.

[Claim 5] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, which are characterized by the step (1) or (3) The base is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and ammonia.

[Claim 6] The silicon-based multi-oxide aerogel according to claim 2, wherein the metal oxide according to the step (1) is a poorly water-soluble metal oxide having a molecular formula of M _x O _y . Wherein M represents a metal atom, 0 represents an atom, and X and y represent the corresponding number of atoms in the formula, respectively.

[Claim 7] The silicon-based multi-oxide aerogel according to claim 2, wherein the metal oxide according to the step (1) comprises alumina, zirconia, titania, iron oxide, tungsten oxide, oxidation Vanadium, cerium oxide, magnesium oxide, copper oxide, indium oxide, gallium oxide, tin oxide, antimony oxide, manganese oxide, cobalt oxide, nickel oxide, zinc oxide, cadmium oxide, chromium oxide, tungsten oxide, antimony oxide, antimony oxide, One or more of cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, and cerium oxide.

[Claim 8] The silicon-based multi-oxide aerogel according to claim 2, wherein the water-soluble metal salt of the step (1) comprises an acidic, basic or neutral soluble metal corresponding to the metal oxide. salt.

[Claim 9] The silicon-based multi-oxide aerogel according to claim 2, wherein the water-soluble metal salt of the step (1) comprises the above metal oxide and corresponding hydroxide, metal and sodium oxide, and oxidation. An alkaline or neutral water-soluble salt formed by the reaction of one or more of potassium.

[Claim 10] The silicon-based multi-oxide aerogel according to claim 2, wherein the water-soluble metal salt of the step (1) comprises the above metal oxide and corresponding hydroxide, metal and hydrochloric acid, nitric acid, An acid or neutral water-soluble salt is formed by the reaction of sulfuric acid, phosphoric acid, carbonic acid, iodic acid, oxalic acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrofluoric acid, sulfurous acid, and nitrous acid.

[Claim 11] The silicon-based multi-oxide aerogel according to claim 2, wherein the water glass is mixed with the water-soluble metal salt in step (1), and the water glass may be directly mixed with the water-soluble metal salt. It is also possible to dilute and mix the water glass and the water-soluble metal salt separately.

[Claim 12] The silicon-based multi-oxide aerogel according to claim 2, characterized in that the water glass and the water-soluble metal salt mixture in the step (1) may be dissolved in water glass and a soluble metal salt. Remixing in the acid, or the water glass and the soluble metal salt are first dissolved in the alkali and then mixed, or the water glass and the soluble metal salt are respectively dissolved in the acid or the alkali and mixed, or the water glass is mixed with the soluble metal salt. It is then dissolved in an acid or a base.

[Claim 13] The multi-oxide aerogel material according to claim 2, characterized in that the water glass and the water-soluble metal salt mixture in the step (1), the water glass and the water-soluble metal salt have a volume ratio of 1:0.01. ~100, preferably 1:0.1~10.

[Claim 14] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the organic solvent in the step (2) is an alcohol. One or more of an ether, an ester, a ketone, an aldehyde, an aliphatic or an aromatic hydrocarbon, preferably having a carbon number of less than 8 in a molecular structure, particularly preferably methanol, ethanol, ethylene glycol, propanol, glycerol, propylene Alcohol, acetone, formaldehyde, acetaldehyde, propionaldehyde.

[Claim 15] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the precipitate formed in the step (2) is filtered. The way to remove, including centrifugal filtration, vacuum filtration, pressure filtration.

[Claim 16] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, characterized in that the one- or multi-element oxide sol of the step (2) The pH is from 0.1 to 4.0, preferably 1.5 3.5.

[Claim 17] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the pH of the step (3) is 3.0 to 7.0. .

[Claim 18] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the step (3) wherein the fiber comprises the fiber comprises One or more of inorganic fibers and organic fibers, and felts, sheets, and cloths made of the above fibers.

[Claim 19] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the organic fiber of the step (3) comprises polyester or nylon. , spandex, acrylic, aramid, polyamide fiber, polyacrylonitrile pre-oxidized fiber, Kevlar fiber

, cellulose fiber, carbon fiber;

[Claim 20] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, wherein the inorganic fiber of the step (3) comprises quartz fiber, High Silicone fiber, aluminum silicate fiber, glass fiber, mullite fiber, silicon carbide fiber, silicon nitride fiber, alumina fiber, boron nitride fiber, basalt fiber, brucite fiber, attapulgite fiber.

[Claim 21] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, characterized by supercritical drying, drying as described in the step (4) The medium comprises ethanol or carbon dioxide; the atmospheric pressure drying comprises hot air drying and infrared drying, and the drying medium for hot air drying is air, nitrogen or carbon dioxide, preferably nitrogen and carbon dioxide; the microwave vacuum drying, the vacuum degree of the equipment before drying should be Below 100 Torr, preferably below 10 Torr.

[Claim 22] The silicon-based one-element aerogel according to claim 1 and the silicon-based multi-oxide aerogel according to claim 2, characterized by the atmospheric drying and microwave described in the step (4) Vacuum drying, the hydrophobic agent is required to hydrophobically modify the gel before drying; supercritical drying, hydrophobization modification before drying, or hydrophobization modification.

[Claim 23] The gel hydrophobic agent according to claim 22, which is a silicone water repellent having a silicon methyl structure, including hexamethyldisilazane, hexamethyldisiloxane, methyl three Methyl silane, methyl triethoxy silane, dimethyl diethoxy silane, dimethyl dimethoxy silane, trimethyl ethoxy silane, trimethyl methoxy silane and trimethyl chloride Silane.