CN113277520A

CN113277520A - Silicon dioxide mesoporous material and preparation method and application thereof

Info

Publication number: CN113277520A
Application number: CN202110693184.4A
Authority: CN
Inventors: 赵明; 英杰; 王伟
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2021-08-20
Anticipated expiration: 2041-06-22
Also published as: CN113277520B

Abstract

The invention discloses a silicon dioxide mesoporous material and a preparation method and application thereof. The method for preparing the silicon dioxide mesoporous material comprises the following steps: mixing a surfactant comprising a copolymer P123 with an acid to obtain a surfactant solution; mixing a surfactant solution with choline chloride-urea ionic liquid to obtain a low-temperature eutectic mixture; mixing the low-temperature eutectic mixed solution with a silicon source to hydrolyze the silicon source to obtain a suspension; adjusting the pH value of the suspension to be not less than 6.2 by using ammonia gas or alkali liquor, and then carrying out ultrasonic reaction on the obtained reaction liquid to obtain a solid product; and calcining the solid product to obtain the silicon dioxide mesoporous material. The method cancels the aging step, can realize the synthesis of the silicon dioxide mesoporous material within several hours at the low temperature of 35 ℃, has simple and environment-friendly process and easy operation and control, can shorten the synthesis period from several days to several hours, and simultaneously the prepared mesoporous material shows good texture tissue and shape.

Description

Silicon dioxide mesoporous material and preparation method and application thereof

Technical Field

The invention belongs to the field of greenhouse gas control, and particularly relates to a silicon dioxide mesoporous material as well as a preparation method and application thereof.

Background

CO₂Is the main gas generated by human activities and is also the most responsible for global warmingThe well known greenhouse gas (GHG). According to the most recent data reported by the strep oceanographic research, by 1/10 of 2020, the carbon dioxide concentration in the atmosphere increased sharply to 413.63ppm, which is why contemporary research is directed to how to slow down or stop this trend. It is predicted that CO will not be reduced further₂The temperature will rise by 5 ℃ by the end of this century. Based on these facts, CO₂Emissions have received increasing scientific attention and various international agreement standard regional policies have been implemented to mitigate CO₂The effect of emissions. Various technologies have been developed to reduce or reverse the effects of GHG emissions, and one of the possible solutions to the problem of GHG emissions is CO₂Capture and Storage (CCS) technologies, which include pre-or post-combustion, oxygenated fuel and electrochemical separation. Despite the advantages and disadvantages of all these strategies, post-combustion is considered the most direct CO in CCS technology₂A capture technique. In post-combustion strategies, aqueous solutions of alkanolamines are often used to reduce CO in industrial processes₂Emissions, such as fossil fuel power plants, cement production, steel and steel manufacturing. Aqueous solutions of primary amines (monoethanolamine (MEA)), secondary amines (diethanolamine (DEA)) and tertiary amines (N-Methyldiethanolamine (MDEA)) can capture CO in a 1:1 molar ratio by generating bicarbonate₂(ii) a However, this technique has some inherent disadvantages, such as the high energy required for solvent regeneration (due to the high weight of water, which is about 70-90% by weight of the aqueous solution), reaction with compounds present in the flue gas, degradation at higher temperatures or in the presence of oxygen in the flue gas, and corrosiveness, which leads to damage to the absorption equipment.

In view of the above, researchers are studying other COs₂The capture process, such as adsorption process, can save energy and be easy to handle and less likely to cause corrosion problems compared to aqueous solutions of amine systems; in addition, the method is used for capturing CO₂More energy saving in the aspect, lower investment cost, capability of using the solid adsorbent at wider temperature, less waste generation in the circulation process, capability of being used without taking excessive environmental precaution measuresThe spent solid adsorbent is disposed. Thus, the capture potential of many solid adsorbents has been studied in recent years, including zeolites, activated carbons, alkaline earth metal oxides, and metal-organic frameworks (MOFs), which, however, adsorb CO through physical processes₂Large pressure and/or temperature gradients are required to achieve good adsorption-desorption performance, and their selectivity is low, sensitive to temperature and humidity; alkaline earth metal oxide adsorbents typically require adsorption and desorption of CO at very high temperatures₂This means that more energy must be expended to heat the adsorption and desorption equipment. To overcome these limitations, functionalization with amine functionality to capture CO from flue gas is performed₂The research work on solid supports has attracted extensive attention from researchers, and several CO-incorporation processes have emerged₂Silica material as a capture agent for CO₂The carbon dioxide capture capacity of the silica support is negligible, but the dispersion, immobilization and blocking of amine functional groups or metals inside the porous silica support can significantly improve its CO₂Performance is captured. Among the mesoporous silica materials, Santa Barbara amorphous No. 15 (SBA-15) is a well-known mesoporous silica material used as a carrier for the above purpose, and is synthesized by a conventional hydrothermal method. However, although the hydrothermal method is widely used for synthesizing mesoporous materials with different morphologies, the main disadvantages of the method are that the synthesis process takes long time (usually 2-3 days) and requires a high temperature aging step of at least 80 ℃ to 150 ℃.

Therefore, it is very important to develop an environmentally friendly, simple and easy method for synthesizing mesoporous materials from the viewpoint of environment and economy.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a mesoporous silica material, and a preparation method and applications thereof. The preparation method cancels the aging step, can realize the synthesis of the silicon dioxide mesoporous material within hours at low temperature (such as 35 ℃), has simple and environment-friendly process and easy operation and control, can shorten the synthesis period from several days to several hours, and simultaneously the prepared mesoporous material shows good texture tissue and morphology.

The present application is based on the following problems and findings:

over the past few years, many groups have employed some promising solvents as reaction media, such as liquids (IL) and eutectic solvents (DES), to prepare novel mesoporous materials. DES is a green designable solvent consisting of two or more components, a Hydrogen Bond Acceptor (HBA) and a Hydrogen Bond Donor (HBD). In 2004, Copper et al used ILs and DES (consisting of choline chloride and urea) as solvents or templates to synthesize zeolite analogues, a process known as "ionothermal" synthesis, which is a promising synthetic process and is widely used in the fields of material science and synthetic coordination chemistry. In the past decades, water and organic solvents have been used as reaction media in conventional synthesis methods, for example, hydrothermal and solvothermal methods for synthesizing mesoporous materials. Instead of using water or an organic solvent directly, DES can be used as a solvent in the reaction medium. Abbott and colleagues in 2003 first explored a new ionic fluid produced by mixing choline chloride as a Hydrogen Bond Acceptor (HBA) and urea as a Hydrogen Bond Donor (HBD). Wherein the melting point of the DES formed is lower than the melting point of the individual components. Recently, researchers have shown increasing interest in using DES in many applications, particularly in isolation and catalysis.

The inventors found that, although DES have many similar physicochemical properties as conventional IL, such as low flammability and volatility, low melting point, high ionic conductivity, high polarity, good chemical stability and adjustable physicochemical properties, they also have several advantages compared to IL, such as ease of preparation, low price, non-toxicity, biodegradability, stability in air and no need for further purification, and can be considered as potential and good candidates for adsorbent modification. In addition to the unique features described above, the inventors have discovered that DES can serve multiple roles as both a precursor, a Structure Directing Agent (SDA), and a reaction medium for the synthesis of desired materials, and can be made in the open, because the vapor pressure of DES is negligibleThe synthesis procedure is carried out in a vessel at ambient pressure, which is one of the main advantages of the proposed process over hydrothermal synthesis in a sealed autoclave. The inventors contemplate that ultrasound radiation and ammonia gas, concentrated ammonia solution (NH) may be used₄OH) or NaOH solution to promote the polymerization of silica instead of hydrothermal process. Sonochemical synthesis is a well-defined process based on the principles of sonochemistry in which molecules chemically react due to the application of powerful ultrasonic radiation. Essentially, there is no chemical reaction during the direct interaction of the ultrasonic radiation with the molecules; however, when ultrasonic radiation interacts with the liquid, an alternating pressure pattern is created, due to the interaction of the ultrasonic radiation with the liquid and the release of ultrasonic energy accumulated in the bubbles, creating acoustic cavitation (the process of bubble formation, expansion and collapse at varying pressures), generating energy with very high local temperatures up to 5000K and pressures of 1000 bar within a duration of a few microseconds. Due to cavitation, in the case of solids, micro-jets are formed which erode, activate and clean the surface and disperse smaller particle agglomerates. The main purpose of the present invention using sonochemical synthesis is to design a technology that is fast, environmentally friendly, energy efficient, economical, easy to use, and can be used at low or ambient temperatures. In conventional hydrothermal methods, the condensation reaction of a silica precursor (e.g., TEOS) takes at least 24 hours, however, the application of sonication in accordance with the present invention results in faster condensation reactions of the silica precursor, thereby facilitating the formation of ordered structures. Furthermore, although NH₄OH is useful in many synthesis systems, particularly in the preparation of monodisperse silica spheres according to the Stober, Fink and Bohn (SFB) methods, but in the synthesis of the mesoporous silica adsorbents of the present invention, NH₄OH or ammonia or other alkaline liquid is used as a catalyst to accelerate the polycondensation of P123-silica precursor aggregates.

Furthermore, the inventors have found that in CO₂In the trapping field, pore-enlarging agents such as alkanes or aromatics may be used to increase the micelle size of the template to obtain enlarged pores, e.g., 1, 3, 5-Trimethylbenzene (TMB), 1, 3, 5-Triisopropylbenzene (TIPB), ethylbenzene, decane, hexaneAlkanes, heptanes, nonanes, cyclohexane, octane, and N, N-dimethylhexadecylamine, and the like. Their addition to the reaction medium can lead to a huge change in the mesostructure and in the specific morphology of the support, but in practice, the use of these swelling agents usually causes a reduction in the order of the mesostructure, even a significant change in the type of mesostructure, while they easily increase the pore size and volume of the micelle-templated support; furthermore, these swelling agents used to synthesize silica supports with large pores are not only toxic but also expensive, for example, TMB is a major municipal Volatile Organic Compound (VOC). These environmental and economic problems limit the industrial application of current processes. Therefore, it is necessary to strictly control the amount of the swelling agent or to find an alternative to the current swelling agent or to effectively adjust the pore size of the mesoporous material without using the swelling agent by adjusting the process conditions.

To this end, in one aspect of the present invention, the present invention provides a method for preparing a silica mesoporous material. According to an embodiment of the invention, the method comprises:

(1) mixing a surfactant comprising copolymer P123 with an acid to obtain a surfactant solution;

(2) mixing the surfactant solution with choline chloride-urea ionic liquid to obtain a low-temperature eutectic mixed solution;

(3) mixing the low-temperature eutectic mixed solution with a silicon source so as to hydrolyze the silicon source to obtain a suspension;

(4) adjusting the pH value of the suspension to be not less than 6.2 by using ammonia gas or alkali liquor;

(5) carrying out ultrasonic reaction on the reaction liquid obtained in the step (4) so as to obtain a solid product;

(6) and calcining the solid product to obtain the silicon dioxide mesoporous material.

The method for preparing the mesoporous silica material according to the above embodiment of the present invention uses the copolymer P123 as the surfactant and the template, uses the choline chloride-urea ionic liquid as the cosolvent and the structure directing agent (i.e., the pore expanding agent), uses the acid to promote the hydrolysis of the silicon source, uses the ammonia gas or the alkali solution and the ultrasonic radiationPromoting the polycondensation reaction of the copolymer P123-silicon dioxide precursor aggregate, enabling the colloidal sol to agglomerate and accelerate the unit cell to grow to obtain a solid product, namely a precursor, and then calcining the precursor to remove the copolymer P123 in the precursor to obtain the silicon dioxide mesoporous material capable of being used as an adsorbent/catalyst carrier. Compared with the prior art which needs a synthesis process consuming at least 2 days (usually 3 days) and a hydrothermal aging step at a temperature of 80-150 ℃, the preparation method disclosed by the invention is mainly based on a molecular solvent, uses DES as a green solvent and cancels the hydrothermal step, can avoid the adverse effect on a mesostructure caused by improper selection or excessive addition of a pore-expanding agent or a swelling agent, can realize the synthesis of the silica mesoporous material within several hours at a low temperature of 35 ℃, is simple in process, environment-friendly and easy to operate, can shorten the synthesis period from several days to several hours, has very important significance from the aspects of environment and economy, has good texture and morphology, can be used as a carrier in many applications to combine organic compounds or metals for different applications, for example CO₂Trapping, separation or catalyst preparation.

In addition, the method for preparing the mesoporous silica material according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the present invention, the solid to liquid ratio of the copolymer P123 to the acid is (3-4.45) g: (60-140) mL, wherein the concentration of hydrogen ions in the acid is 1-2 mol/L.

In some embodiments of the invention, the acid comprises at least one selected from hydrochloric acid, nitric acid and sulfuric acid.

In some embodiments of the invention, the surfactant is copolymer P123.

In some embodiments of the invention, in step (2), the choline chloride-urea ionic liquid has a molar ratio of choline chloride to urea of 1: 2.

In some embodiments of the invention, in the step (2), the solid-to-liquid ratio of the copolymer P123 to the choline chloride-urea ionic liquid is (3-4.45) g: (2-10) mL.

In some embodiments of the invention, in step (3), the silicon source is silicate (solution) or tetraethyl orthosilicate (TEOS).

In some embodiments of the present invention, in the step (3), the solid-to-liquid ratio of the copolymer P123 to the silicon source is (3-4.45) g: (10-14) mL.

In some embodiments of the invention, in the step (4), the pH value of the suspension is adjusted to 6.2-8 by using ammonia gas or alkali liquor.

In some embodiments of the invention, in the step (4), the alkali liquor is ammonia water and/or sodium hydroxide solution, the mass concentration of the ammonia water is 25-28 wt%, and the concentration of the sodium hydroxide solution is 5.5-6.5 mol/L.

In some embodiments of the present invention, in step (5), the ultrasonic reaction has a frequency of 36 to 40kHz and a time of 1 +/-0.1 h.

In some embodiments of the invention, in step (5), the ultrasonication reaction is performed under stirring conditions in a water bath at a temperature of 35-37 ℃.

In some embodiments of the invention, in step (6), the temperature of the calcination treatment is 550 ± 5 ℃ for 6 ± 0.2 h.

According to a second aspect of the present invention, the present invention provides a mesoporous silica material obtained by the above method for preparing a mesoporous silica material. Compared with the prior art, the silicon dioxide mesoporous material has simple preparation process, environmental protection and high efficiency, shows good texture structure and morphology, has larger comparative area and appropriate proportion of total pore volume and average pore size, can be used as a carrier in many applications to combine organic compounds or metals for different applications, such as CO₂Trapping, separation or catalyst preparation.

According to a third aspect of the present invention, the present invention provides the above method for preparing the mesoporous silica material and/or the use of the mesoporous silica material in the fields of adsorbents and catalysts. Compared with the prior art, the preparation method and the mesoporous material not only have simple process, environmental protection and easy operation, but also have the advantages that the synthesis period can be shortened to several hours, the (obtained) mesoporous material shows good texture structure and form, has larger comparative area and appropriate proportion of total pore volume and average pore diameter size, can be used as a carrier to be combined with organic compounds or metals for different applications, has more obvious advantages in the field of solid adsorbents or catalysts, and can obtain better environmental benefit and economic benefit when being used in the fields of adsorbents and catalysts.

According to a fourth aspect of the present invention, the present invention provides a mesoporous silica adsorbent. According to an embodiment of the present invention, the mesoporous silica adsorbent comprises a carrier, wherein the carrier is the mesoporous silica material or the mesoporous silica material obtained by the preparation method. The mesoporous silica adsorbent has the advantages of easy acquisition of the carrier, low cost and large limit loading capacity, and compared with liquid adsorption, the mesoporous silica adsorbent can save energy and is easy to treat, is unlikely to cause corrosion problems, generates less waste in the using process, and can treat used solid adsorbent without taking excessive environmental precautionary measures.

In some embodiments of the present invention, the mesoporous silica adsorbent further comprises: an amine supported on the support.

In some embodiments of the invention, the amine is tetraethylenepentamine and the mass ratio of the amine to the carrier is 1: 1.

According to a fifth aspect of the present invention, the present invention provides a method for preparing the mesoporous silica adsorbent. According to an embodiment of the invention, the method comprises:

mixing amine and a volatile organic solvent to obtain a mixed solution;

and mixing the mixed solution with the silicon dioxide mesoporous material and then drying to obtain the mesoporous silicon dioxide adsorbent.

The method for preparing the mesoporous silica adsorbent of the embodiment of the invention has simple process, and the prepared mesoporous silica adsorbentAlso shows higher CO₂Absorption and CO₂/N₂Selectively in CO₂Has wide application prospect in the aspects of capture and storage.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a comparison of the small angle X-ray diffraction patterns of the sample INH THU (2) synthesized according to example 3, the sample INH THU (3) synthesized according to example 5 and the sample INH THU (4) synthesized according to example 7 of the present invention.

FIG. 2 is a comparison of the small angle X-ray diffraction patterns of the sample INH THU (1) synthesized according to example 1, the sample INH THU (6) synthesized according to example 11 and the sample INH THU (7) synthesized according to example 13 of the present invention.

FIG. 3 is a comparison of the small angle X-ray diffraction patterns of the sample INH THU (8) synthesized according to example 15 and the sample INH THU (9) synthesized according to example 17 of the present invention.

Fig. 4 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (1) synthesized according to example 1 of the present invention.

Fig. 5 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (2) synthesized according to example 3 of the present invention.

Fig. 6 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (3) synthesized according to example 5 of the present invention.

Fig. 7 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (4) synthesized according to example 7 of the present invention.

Fig. 8 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (5) synthesized according to example 9 of the present invention.

Fig. 9 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (6) synthesized according to example 11 of the present invention.

FIG. 10 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (7) synthesized according to example 13 of the present invention.

Fig. 11 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (8) synthesized according to example 15 of the present invention.

Fig. 12 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (9) synthesized according to example 17 of the present invention.

Fig. 13 is a nitrogen adsorption-desorption isotherm diagram of the mesoporous sample INH THU (10) synthesized according to example 19 of the present invention.

FIG. 14 is a thermogravimetric comparison of the precursor synthesized according to example 1 of the invention (i.e. a white powder sample without calcination to remove the copolymer P123, named As synth INH THU), the mesoporous sample INH THU (1) and the sample TEPA (50%)/INH THU (1) synthesized according to example 2.

FIG. 15 is a graph comparing thermogravimetric analysis curves of a precursor synthesized according to example 5, a mesoporous sample INH THU (3), and a sample TEPA (50%)/INH THU (3) synthesized according to example 6.

FIG. 16 is a graph comparing thermogravimetric analysis curves of a precursor synthesized according to example 15, a mesoporous sample INH THU (8), and a sample TEPA (50%)/INH THU (8) synthesized according to example 16.

FIG. 17 is CO of an adsorbent sample TEPA (50%)/INH THU (1) synthesized according to example 2 of the present invention₂The original plot is taken with the left Y-1 axis being the weight axis and the right Y-2 axis being the temperature axis.

FIG. 18 is CO of TEPA (50%)/INH THU (3) of an adsorbent sample synthesized in example 6 according to the present invention₂The original image is absorbed.

FIG. 19 is CO of an adsorbent sample TEPA (50%)/INH THU (8) synthesized in accordance with example 16 of the present invention₂The original image is absorbed.

FIG. 20 is CO of an adsorbent sample TEPA (50%)/INH THU (1) synthesized according to example 2 of the present invention₂Absorption capacity and adsorption index as a function of increasing cycle number.

FIG. 21 is CO of TEPA (50%)/INH THU (3) of an adsorbent sample synthesized in example 6 according to the present invention₂Absorption capacity and adsorption index as a function of increasing cycle number.

FIG. 22 is a view according to the present inventionInventive example 16 synthetic sorbent sample TEPA (50%)/INH THU (8) CO₂Absorption capacity and adsorption index as a function of increasing cycle number.

FIG. 23 is CO of an adsorbent sample TEPA (50%)/INH THU (1) synthesized according to example 2 of the present invention₂Raw graph of cyclic adsorption-desorption performance.

FIG. 24 is CO of TEPA (50%)/INH THU (3) of an adsorbent sample synthesized in example 6 according to the present invention₂Raw graph of cyclic adsorption-desorption performance.

FIG. 25 is a sample of sorbent synthesized in accordance with example 16 of the present invention, TEPA (50%)/INH THU (8) CO₂Raw graph of cyclic adsorption-desorption performance.

FIG. 26 is a flow chart of a method for preparing a mesoporous silica material according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In one aspect of the present invention, the present invention provides a method for preparing a mesoporous silica material. The method adopts an ion-non-hydrothermal method, eliminates an aging step, can realize the synthesis of the silicon dioxide mesoporous material within several hours at a low temperature of 35 ℃, has simple and environment-friendly process and easy operation and control, can shorten the synthesis period from several days to several hours, and simultaneously the prepared mesoporous material shows good texture tissue and form. The method for preparing the mesoporous silica material is described in detail below with reference to fig. 26. According to an embodiment of the invention, the method comprises:

s100, mixing a surfactant containing the copolymer P123 with an acid to obtain a surfactant solution

According to the embodiment of the invention, the copolymer P123 is used as a surfactant and a template, acid is used for promoting hydrolysis of a silicon source, a silicon source hydrolysis product is attached to the surface of the copolymer P123 in the subsequent step and is subjected to condensation polymerization and unit cell growth, and then the copolymer P123 is removed through calcination to obtain the silica material with a mesoporous structure. The surfactant solution was obtained by thoroughly mixing the copolymer P123 and the acid solution. Wherein the copolymer P123 is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

According to a specific embodiment of the present invention, the kind of the acid in the present invention is not particularly limited, and may be selected by those skilled in the art according to actual needs, for example, the acid may include at least one selected from hydrochloric acid, nitric acid and sulfuric acid, and may preferably be hydrochloric acid.

According to another embodiment of the present invention, the surfactant may be only the copolymer P123, so that not only the final mesoporous silica material can be prevented from having an excessively large pore size, but also the mesoporous silica material can have a large total pore volume and a large specific surface area, and at the same time, adverse effects of toxicity or high cost caused by tetramethylbenzidine used as a pore-expanding agent can be avoided, thereby not only protecting the environment, but also further improving the loading capacity and adhesion of the carrier when the mesoporous silica material is used as a carrier of an adsorbent or a catalyst, and ensuring the effects of the adsorbent and the catalyst.

According to another embodiment of the present invention, the solid-to-liquid ratio of the copolymer P123 to the acid may be (3-4.45) g: (60-140) mL, for example, 4g/100mL, 4.45g/110mL, 4g/120mL or 4.45g/140mL, etc., and the concentration of hydrogen ions in the acid can be 1-2mol/L, for example, 1mol/L, 1.5mol/L, 2mol/L, etc., when preparing the silica mesoporous material, the amount of the silicon source depends on the amount of the copolymer P123, the inventors found that, based on the amount of the copolymer P123, when the amount of the acid is too small, it is not favorable for promoting the hydrolysis of the subsequent silicon source and the agglomeration of the sol particles, and further is not favorable for reducing the average pore diameter of the mesoporous material and improving the order degree of the mesoporous material, and with the increase of the amount or the concentration of the acid, the average pore diameter of the finally prepared mesoporous material can be reduced and the order of the mesoporous material can be increased, and when the amount of the acid is too much, not only the acid is wasted, The solid-to-liquid ratio of the copolymer P123 to the acid and the concentration of hydrogen ions in the acid are controlled to be in the range, so that the finally prepared silicon dioxide mesoporous material has smaller average pore diameter, larger specific surface area and higher order degree.

S200, mixing the surfactant solution with choline chloride-urea ionic liquid to obtain a low-temperature eutectic mixture

According to the embodiments of the present invention, the inventors found that, by using a green solvent choline chloride-urea ionic liquid (i.e., DES solution) as a structure directing agent, since DES is not volatile at normal temperature, the polycondensation reaction of the copolymer P123-silica precursor can be performed in an open container under ambient pressure, thereby making it possible to subsequently perform the ultrasonic reaction under a low temperature environment (e.g., 35 ℃).

According to a specific embodiment of the present invention, the choline chloride-urea ionic liquid may have a molar ratio of choline chloride to urea of 1:2, thereby ensuring that the choline chloride-urea exists in a liquid form.

According to another embodiment of the invention, the solid-to-liquid ratio of the copolymer P123 to the choline chloride-urea ionic liquid may be (3-4.45) g: (2-10) mL, for example, 4g/2mL, 4g/5mL, 4g/10mL, 4.45g/2mL, or 4.45g/10mL, etc., and the inventors have found that the amount of DES used affects not only the average pore diameter and total pore volume of the mesoporous material but also the degree of order of the mesoporous material, based on the amount of the copolymer P123, the specific surface area, the total pore volume and the order degree of the finally prepared silica mesoporous material are increased along with the increase of the amount of the DES or the increase of the concentration of the DES in the total mixed solution (i.e. the reaction solution obtained in the step S400), but with the increase of the DES dosage, the order degree of the mesoporous material is reduced, and by controlling the copolymer P123 and the choline chloride-urea ionic liquid to be in the solid-to-liquid ratio range, the finally prepared mesoporous material has higher order degree, proper average pore diameter, total pore volume and larger specific surface area. The total pore volume in the present invention refers to the total pore volume (cm) per unit mass of the mesoporous material³/g)。

S300, mixing the low-temperature eutectic mixed solution with a silicon source to hydrolyze the silicon source to obtain a suspension

According to the embodiment of the invention, the low-temperature eutectic mixed solution and the silicon source are mixed, so that the silicon source can be hydrolyzed to obtain the white precipitate, wherein the two can be continuously stirred in the mixing process to promote the hydrolysis of the silicon source.

According to another embodiment of the present invention, the silicon source may be tetraethyl orthosilicate (TEOS), and the solid-to-liquid ratio of the copolymer P123 to the silicon source may be (3-4.45) g: (10-14) mL, for example, 4g/14mL, 4.45g/10mL or 4g/10mL, etc., and the inventors found that the amount of the silicon source also affects the total pore volume, the average pore diameter and the order degree of the finally prepared mesoporous material, and based on the amount of the copolymer P123, if the amount of the silicon source is too large, not only would the total pore volume of the finally prepared mesoporous material be too small, but also the order degree of the mesoporous structure would not be favorably improved, but if the amount of the silicon source is too small, the average pore diameter of the mesoporous material would not be favorably reduced, and when the copolymer P123 and the silicon source are controlled to be in the above solid-to-liquid ratio range, the finally prepared silica mesoporous material can have a larger total pore volume, a smaller average pore diameter and a higher order degree, and the specific surface area of the material is larger.

S400, adjusting the pH value of the suspension to be not less than 6.2 by using ammonia gas or alkali liquor

According to the embodiments of the present invention, the inventors found that, when the polycondensation reaction of the copolymer P123-silica precursor aggregate is performed under a weakly acidic condition, although the finally obtained mesoporous material has a large specific surface area, the average pore diameter of the mesoporous material is too small, the total pore volume is also small, and the mesoporous material is not suitable for being used as a solid adsorbent or a catalyst carrier, and when the polycondensation reaction of the copolymer P123-silica precursor aggregate is catalyzed under an alkaline environment, the sol colloidal particle agglomeration is more facilitated and the cell growth is accelerated to obtain a solid product, so that the finally obtained mesoporous silica material has a large specific surface area, a small average pore diameter and a large total pore volume. When the pH value of the turbid liquid is adjusted by using the alkali liquid, the alkali liquid can be dropwise added into the turbid liquid, and meanwhile, the titration end point and/or the pH value at the titration end point can be judged by using pH test paper.

According to an embodiment of the present invention, the pH value of the suspension can be adjusted to 6.2-8, for example, 6.2, 6.4, 7 or 8, by using ammonia gas or alkali solution, thereby better promoting the polycondensation reaction of the copolymer P123-silica precursor aggregate, saving unnecessary waste of ammonia gas or alkali solution, and improving the adjustment efficiency.

According to another embodiment of the present invention, the type of the alkaline solution used in the present invention for adjusting the pH value is not particularly limited, and those skilled in the art can select the alkaline solution according to actual needs, for example, the alkaline solution is ammonia and/or sodium hydroxide solution, and ammonia gas can be introduced into the turbid solution to adjust the pH value. Further, the mass concentration of the ammonia water may be 25 to 28 wt%, for example, 25 wt% or 27 wt%, and the concentration of the sodium hydroxide solution may be 5.5 to 6.5mol/L, for example, 5.6mol/L, 5.8mol/L, 6mol/L, 6.2mol/L, or 6.4 mol/L. Preferably, the alkali solution may be ammonia water, and the inventor finds that the ammonia water is more beneficial to reducing the average pore diameter and increasing the total pore volume of the finally prepared mesoporous material compared with a sodium hydroxide solution.

S500, carrying out ultrasonic reaction on the reaction liquid obtained in the step S400 to obtain a solid product

According to the embodiment of the invention, the inventor finds that the ultrasonic radiation can be used for promoting the polymerization of the silicon dioxide in the alkaline environment instead of the hydrothermal synthesis process in a sealed autoclave, compared with the conventional hydrothermal method in which the condensation reaction of a silicon dioxide precursor (such as TEOS) usually requires 2-3 days and a high temperature of 80-150 ℃, the ultrasonic reaction can be carried out at a low temperature (such as 35 ℃) to realize the synthesis of the silicon dioxide mesoporous material within a few hours, the process is simple, environment-friendly and easy to operate, the synthesis period can be shortened from a few days to a few hours, and the method has important significance from the environmental and economic aspects. Further, the resulting white precipitate may be filtered, washed and dried after the ultrasonication reaction to obtain a white powder, i.e., a solid product.

According to one embodiment of the present invention, the frequency of the ultrasonic reaction may be 36-40kHz, for example, 36kHz, 37kHz, 38kHz, 39kHz or 40kHz, etc., and the time may be 1 ± 0.1h, for example, 0.9h, 1h or 1.1h, etc. The inventor finds that the ultrasonic frequency and the ultrasonic time also obviously influence the mesoporous structure and the preparation efficiency of the finally prepared silicon dioxide mesoporous material, if the ultrasonic frequency is too low or the ultrasonic time is too short, the polycondensation efficiency of the P123-silicon dioxide precursor aggregate is not favorably improved, and meanwhile, the order degree of the mesoporous material is not favorably improved, so that the preparation efficiency and the product effect are influenced; by controlling the ultrasonic conditions, the preparation efficiency can be obviously improved, and the silicon dioxide mesoporous material with the characteristics of small average pore diameter, large specific surface area and high degree of order can be obtained.

According to one embodiment of the present invention, the ultrasonic reaction may be performed under stirring conditions in a water bath, and the temperature of the water bath may be 35-37 ℃, for example, 35 ℃, 36 ℃ or 37 ℃. The inventor finds that when the reaction is carried out by utilizing ultrasonic radiation in an alkaline environment, the reaction temperature can be reduced to be not higher than 37 ℃, and is preferably not lower than 35 ℃, if the temperature is lower than 35 ℃, the synthesis of mesoporous silica is not facilitated, only amorphous or disordered mesoporous silica materials can be synthesized, and in order to control the stable proceeding of the ultrasonic reaction, the heating temperature can be controlled to be unchanged by utilizing a water bath mode, so that the order degree and the uniformity of the finally prepared mesoporous silica materials can be further improved.

S600, calcining the solid product to obtain the silicon dioxide mesoporous material

According to the embodiment of the invention, the copolymer P123 in the solid product can be sufficiently removed by calcining the solid product, so that the silica material with the mesoporous structure is obtained.

According to one embodiment of the present invention, the temperature of the calcination process may be 550 + -5 deg.c, for example, 545 ℃ at 548 ℃, 550 ℃, 552 ℃ or 555 ℃, and the like, and the time can be 6 +/-0.2 h, for example, 5.8h, 5.9h, 6h, 6.1h or 6.2h, and the like, wherein the temperature rise rate of the calcination treatment in the temperature rise process can be 5-15 ℃/min, for example, 10 ℃/min, the inventors found that if the calcination temperature is too low or the calcination time is too short, it is not favorable to sufficiently and rapidly remove the copolymer P123 in the solid product, and the treatment efficiency and treatment effect are affected, if the calcination temperature is too high or the calcination time is too long, unnecessary energy waste can be caused, and the treatment efficiency can be reduced.

According to yet another embodiment of the present invention, the solid-to-liquid ratio of the surfactant comprising copolymer P123 to the acid may be (3-4.45) g: (60-140) mL, wherein the concentration of hydrogen ions in the acid can be 1-2 mol/L; the mol ratio of choline chloride to urea in the choline chloride-urea ionic liquid can be 1:2, and the solid-to-liquid ratio of the copolymer P123 to the choline chloride-urea ionic liquid can be (3-4.45) g: (2-10) mL; the silicon source can be tetraethyl orthosilicate (TEOS), and the solid-to-liquid ratio of the copolymer P123 to the silicon source can be (3-4.45) g: (10-14) mL; the pH value of the suspension can be adjusted to 6.2-8 by using ammonia water and/or sodium hydroxide solution, the mass concentration of the ammonia water can be 25-28 wt%, and the concentration of the sodium hydroxide solution can be 5.5-6.5 mol/L; the frequency of the ultrasonic reaction can be 36-40kHz, the time can be 1 +/-0.1 h, the ultrasonic reaction can be carried out under the condition of water bath stirring, and the temperature can be 35-37 ℃, for example, 35 ℃; the temperature of the calcination treatment may be 550 + -5 deg.C and the time may be 6 + -0.2 h.

According to a specific embodiment of the present invention, it is possible to: 1) copolymer P123 was dissolved in 2M hydrochloric acid solution. 2) The required amount of choline chloride-urea ionic liquid is added to the surfactant solution. 3) TEOS was added to the surfactant solution as a source of silica, and stirred to obtain a white precipitate. 4) Adding a required amount of ammonium hydroxide solution into the mixture, and then stirring for a specific time to ensure that the pH value of the mixture is 7-8 so as to promote the polycondensation reaction of the P123-TEOS precursor aggregate. 5) The mixture was subjected to ultrasonic irradiation to accelerate condensation of TEOS, filtered and the resulting white precipitate was washed and dried to obtain a white powder. 6) In order to remove the copolymer P123 from the pores to obtain mesoporous silica, the white solid may be calcined in air at 550 ℃ for 6 hours using a muffle furnace. Wherein, step 1) can also be dissolving the required amount of copolymer P123, CTAB and TMB in 1.5M hydrochloric acid solution.

According to yet another embodiment of the present invention, the mesoporous silica materials prepared in the present invention exhibit good texture properties and morphology and can be used as functionalized supports of amines on these materials, and the inventors have found that among the amines used to impregnate silica supports, Tetraethylenepentamine (TEPA) exhibits high CO due to its high N concentration₂Absorption and CO₂/N₂Selectivity, TEPA can therefore be used to examine CO impregnating the mesoporous silica material₂Capture and cycle performance.

In summary, in the method for preparing a silica mesoporous material according to the above embodiment of the present invention, the copolymer P123 is used as a surfactant and a template, the choline chloride-urea ionic liquid is used as a cosolvent and a structure directing agent (i.e., a pore expanding agent), the acid is used to promote hydrolysis of a silicon source, the ammonia gas or alkali solution and the ultrasonic radiation are used to promote a polycondensation reaction of the copolymer P123-silica precursor aggregate, so as to aggregate sol particles and accelerate cell growth to obtain a solid product, i.e., a precursor, and then the precursor is calcined to remove the copolymer P123 in the precursor, so as to obtain the silica mesoporous material capable of being used as an adsorbent/catalyst carrier. Compared with the prior art which needs a synthesis process consuming at least 2 days (usually 3 days) and a hydrothermal aging step at a temperature of 80-150 ℃, the preparation method disclosed by the invention is mainly based on a molecular solvent, uses DES as a green solvent and cancels the hydrothermal step, can avoid the adverse effect on a mesostructure caused by improper selection or excessive addition of a pore-expanding agent or a swelling agent, can realize the synthesis of the silicon dioxide mesoporous material within several hours at a low temperature of 35 ℃, is simple in process, environment-friendly and easy to operate, can shorten the synthesis period from several days to several hours, and has very important significance from the aspects of environment and economy, and the silicon dioxide mesoporous material prepared by the method also has good texture tissue and shapePhases, which can be used as supports in many applications for binding organic compounds or metals for different applications, e.g. CO₂Trapping, separation or catalyst preparation.

According to a second aspect of the present invention, the present invention provides a mesoporous silica material obtained by the above method for preparing a mesoporous silica material. Compared with the prior art, the silicon dioxide mesoporous material has simple preparation process, environmental protection and high efficiency, shows good texture structure and morphology, has larger comparative area and appropriate proportion of total pore volume and average pore size, can be used as a carrier in many applications to combine organic compounds or metals for different applications, such as CO₂Trapping, separation or catalyst preparation. It should be noted that the characteristics and effects described for the method for preparing the mesoporous silica material are also applicable to the mesoporous silica material, and are not described in detail herein.

According to a third aspect of the present invention, the present invention provides the above method for preparing the mesoporous silica material and/or the use of the mesoporous silica material in the fields of adsorbents and catalysts. Compared with the prior art, the preparation method and the mesoporous material not only have simple process, environmental protection and easy operation, but also have the advantages that the synthesis period can be shortened to several hours, the (obtained) mesoporous material shows good texture structure and form, has larger comparative area and appropriate proportion of total pore volume and average pore diameter size, can be used as a carrier to be combined with organic compounds or metals for different applications, has more obvious advantages in the field of solid adsorbents or catalysts, and can obtain better environmental benefit and economic benefit when being used in the fields of adsorbents and catalysts. It should be noted that the characteristics and effects described for the above mesoporous silica material and the method for preparing the mesoporous silica material are also applicable to the purpose, and are not described in detail herein.

According to a fourth aspect of the present invention, the present invention provides a mesoporous silica adsorbent. According to an embodiment of the present invention, the mesoporous silica adsorbent comprises a carrier, wherein the carrier is the mesoporous silica material or the mesoporous silica material obtained by the preparation method. The mesoporous silica adsorbent has the advantages of easy acquisition of the carrier, low cost and large limit loading capacity, and compared with liquid adsorption, the mesoporous silica adsorbent can save energy and is easy to treat, is unlikely to cause corrosion problems, generates less waste in the using process, and can treat used solid adsorbent without taking excessive environmental precautionary measures. It should be noted that the characteristics and effects described for the above mesoporous silica material and the method for preparing the mesoporous silica material are also applicable to the mesoporous silica adsorbent, and are not described in detail herein.

According to one embodiment of the present invention, when mesoporous silica adsorbents are used for CO capture₂When the mesoporous silica material is used, the mesoporous silica material can be introduced into a carrier suitable for CO₂The mesoporous silica adsorbent for capturing the target amine component may further include: the amine supported on the carrier, wherein the type of the supported amine is not particularly limited and may be selected by those skilled in the art according to actual needs, for example, the amine may be Tetraethylenepentamine (TEPA), primary amine (monoethanolamine (MEA)), secondary amine (diethanolamine (DEA)), tertiary amine (N-Methyldiethanolamine (MDEA)), or the like. Preferably, the supported amine may be Tetraethylenepentamine (TEPA), which the inventors have found shows high CO due to its high N concentration among the amines used to impregnate the silica support₂Absorption and CO₂/N₂And (4) selectivity.

According to still another embodiment of the present invention, the loading amount of the amine in the mesoporous silica adsorbent is not particularly limited, and can be selected by those skilled in the art according to actual needs, for example, when the amine is Tetraethylenepentamine (TEPA), the mass ratio of the amine to the carrier can be 1:1, thereby further improving CO-selectivity₂The amount of adsorption of (3).

According to a fifth aspect of the present invention, the present invention provides a method for preparing the mesoporous silica adsorbent. According to an embodiment of the invention, the method comprises: dissolving amine and volatile organic solventMixing the agents to obtain a mixed solution; and mixing the mixed solution with the silicon dioxide mesoporous material and then drying to obtain the mesoporous silicon dioxide adsorbent. The preparation method is simple in process, and the prepared mesoporous silica adsorbent also shows high CO₂Absorption and CO₂/N₂Selectively in CO₂Has wide application prospect in the aspects of capture and storage. It should be noted that the features and effects described for the mesoporous silica adsorbent are also applicable to the method for preparing the mesoporous silica adsorbent, and are not described in detail herein.

According to one embodiment of the invention, the desired amount of amine (e.g., TEPA) can be mixed with methanol and stirred at room temperature until completely dissolved. Then, a desired amount of the silica mesoporous material was added to the mixture, and stirred at room temperature. Wherein the weight ratio of methanol/silica mesoporous material can be kept constant at 8:1 and the weight ratio of amine/silica mesoporous material can be kept constant at 1:1, the final mixture is placed in a vacuum drying oven to produce white solid powder.

It should be noted that the method for preparing the mesoporous silica material according to the above embodiment of the present invention adopts an ion-non-hydrothermal method, which may be referred to as "INH" for short, and the prepared mesoporous silica material may be named as "THU", wherein the mesoporous silica material prepared by using the method and only using the copolymer P123 as a surfactant may be named as "INH THU", and the mesoporous silica adsorbent using "INH THU" as a carrier to support Tetraethylenepentamine (TEPA) may be named as "TEPA/INH THU".

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

4g of mixed copolymer P123 with120mL of 2mol/L hydrochloric acid was mixed, followed by stirring at room temperature to dissolve the surfactant. Then, 10mL of DES (choline chloride-urea composition at a molar ratio of 1: 2) was added to the surfactant solution. The mixture was placed in a water bath and stirred at 35 ℃ for 1 hour, then 14mL TEOS was added dropwise and stirred vigorously at 35 ℃ for 4 hours to give a white precipitate. Add about 29mL NH₄The OH solution adjusted the pH of the mixture to 8 (as determined using pH paper) and was then stirred at 35 ℃ for 1 hour. In the next step, the mixture was sonicated with an ultrasonic bath at 35 ℃ for 1 hour, the resulting white precipitate was filtered, washed with warm water and ethanol, then dried at 80 ℃ for 24 hours, and finally the white powder was placed in a muffle furnace and calcined at 550 ℃ for 6 hours in an air atmosphere to remove the copolymer P123 in the pores, yielding a silica mesoporous material, the synthesized sample being referred to as INH THU (1).

Example 2

0.25g of TEPA and 2g of methanol were mixed and stirred at room temperature for 10 minutes until complete dissolution. Then, 0.25g of INH THU (1) obtained in example 1 was added to the mixture, and the resulting slurry was stirred at room temperature in a closed bottle for 3 hours. After stirring, sonication was carried out for 10 minutes. The final mixture was dried in a vacuum oven at 80 ℃ for 24 hours to obtain a solid powder. The synthesized sample was labeled TEPA (50%)/INH THU (1).

Example 3

4.45g of the mixed copolymer P123 was mixed with 110mL of 2mol/L hydrochloric acid, followed by stirring at room temperature to dissolve the surfactant. Then, 10mL of DES (choline chloride-urea composition at a molar ratio of 1: 2) was added to the surfactant solution. The mixture was placed in a water bath and stirred at 35 ℃ for 1 hour, then 14mL TEOS was added dropwise and stirred at 35 ℃ for 4 hours to give a white precipitate. Add approximately 20mL NH₄The OH solution adjusted the pH of the mixture to 8 (as determined using pH paper) and was then stirred at 35 ℃ for 1 hour. In the next step, the mixture was sonicated for 1 hour with a 35 ℃ ultrasound bath, the resulting white precipitate was filtered, washed with warm water and ethanol, then dried at 80 ℃ for 24 hours, and finally the white powder was placed in a muffle furnaceCalcining at 550 ℃ for 6 hours in an air atmosphere, removing the copolymer P123 in the pores to obtain a silica mesoporous material, and synthesizing a sample called INH THU (2).

Example 4

The difference from example 2 is that: a sample was synthesized using the INH THU (2) obtained in example 3, and the synthesized sample was labeled TEPA (50%)/INH THU (2).

Example 5

The difference from example 3 is that: 140mL of 2mol/L hydrochloric acid was used during the synthesis. The synthesized sample was named INH THU (3).

Example 6

The difference from example 2 is that: a sample was synthesized using the INH THU (3) obtained in example 5, and the synthesized sample was labeled TEPA (50%)/INH THU (3).

Example 7

The difference from example 3 is that: during the synthesis, 140mL of 2mol/L hydrochloric acid was used, and 2mL of DES (choline chloride-urea composition at a 1:2 molar ratio) was added to the surfactant solution. The synthesized sample was named INH THU (4).

Example 8

The difference from example 2 is that: a sample was synthesized using the INH THU (4) obtained in example 7, and the synthesized sample was labeled TEPA (50%)/INH THU (4).

Example 9

The difference from example 3 is that: 140mL of 2mol/L hydrochloric acid was used during the synthesis. The pH of the mixture was adjusted to 8 using 6mol/L NaOH solution. The synthesized sample was named INH THU (5).

Example 10

The difference from example 2 is that: a sample was synthesized using the INH THU (5) obtained in example 9, and the synthesized sample was labeled TEPA (50%)/INH THU (5).

Example 11

The difference from example 1 is that: 10mL TEOS and 2mL DES were used during the synthesis. The synthesized sample was named INH THU (6).

Example 12

The difference from example 2 is that: a sample was synthesized using the INH THU (6) obtained in example 11, and the synthesized sample was labeled TEPA (50%)/INH THU (6).

Example 13

The difference from example 1 is that: 10mL TEOS and 5mL DES were used during the synthesis. The synthesized sample was named INH THU (7).

Example 14

The difference from example 2 is that: a sample was synthesized using the INH THU (7) obtained in example 13, and the synthesized sample was labeled TEPA (50%)/INH THU (7).

Example 15

4g of the mixed copolymer P123 was mixed with 100mL of 1mol/L sulfuric acid, followed by stirring at room temperature to dissolve the surfactant. Then, 2mL of DES (choline chloride-urea composition at a molar ratio of 1: 2) was added to the surfactant solution. The mixture was placed in a water bath and stirred at 35 ℃ for 1 hour, then 10mL TEOS was added dropwise and stirred vigorously at 35 ℃ for 4 hours to give a white precipitate. Dropwise adding 25-28 wt% of NH₄The OH solution was stirred at 35 ℃ for 30 minutes until the pH of the mixture was adjusted to 8 (as determined using pH paper). In the next step, the mixture was sonicated with an ultrasonic bath at 35 ℃ for 1 hour, the resulting white precipitate was filtered, washed with warm water and ethanol, then dried at 80 ℃ for 24 hours, and finally the white powder was placed in a muffle furnace and calcined at 550 ℃ for 6 hours in an air atmosphere to remove the copolymer P123 in the pores, yielding a silica mesoporous material, the synthesized sample being referred to as INH THU (8).

Example 16

The difference from example 2 is that: a sample was synthesized using the INH THU (8) obtained in example 15, and the synthesized sample was labeled TEPA (50%)/INH THU (8).

Example 17

The difference from example 15 is that: the pH of the mixture was adjusted to about 6.2-6.4 during the synthesis using NH4OH solution. The synthesized sample was named INH THU (9).

Example 18

The difference from example 2 is that: a sample was synthesized using the INH THU (9) obtained in example 17, and the synthesized sample was labeled TEPA (50%)/INH THU (9).

Example 19

The difference from example 15 is that: the pH of the mixture is adjusted to about 4.4-4.6 during the synthesis using NH4OH solution. The synthesized sample was named INH THU (10).

Example 20

The difference from example 2 is that: a sample was synthesized using the INH THU (10) obtained in example 19, and the synthesized sample was labeled TEPA (50%)/INH THU (10).

Evaluation:

1. evaluation of the Crystal Structure and mesoporous Structure of mesoporous Material

The crystal structure of the samples was characterized by X-ray diffraction using a D8Advance X-ray diffractometer (Bruker, Germany, Cu-K)_αRadiation) at 0.02 °/min^-1The continuous scan rate of (a) obtains a small angle X-ray diffraction (SAXRD) pattern with a 2 theta angle in the range of 0.5 to 5 deg. Measurement of sample Properties such as specific surface area (S) during adsorption and desorption Using Quantachrome Autoadsorption apparatus (Autosorb-1, Quantachrome, USA)_BET) Total pore volume, mean pore size, and BJH pore size.

FIG. 1 is a small angle X-ray diffraction contrast diagram of synthesized samples INH THU (2), INH THU (3) and INH THU (4), FIG. 2 is a small angle X-ray diffraction contrast diagram of synthesized samples INH THU (1), INH THU (6) and INH THU (7), and FIG. 3 is a small angle X-ray diffraction contrast diagram of synthesized samples INH THU (8) and INH THU (9). As can be seen from FIGS. 1-3, the small angle X-ray diffraction patterns of the synthesized samples such as INH THU (4), INH THU (6) and INH THU (7) show three well-resolved peaks after calcination, the first of which reflects at 0.90-0.95 ° for 2 θ and the other two peaks which reflect at 1.5-2 ° for 2 θ and are relatively weak, which confirm that ordered materials can be formed in the presence of DES, and that finding the correct molar ratio of components is important for obtaining well-ordered materials, the present invention attempts different molar ratios for the components of the mixture, e.g., by comparing the INH THU (6) and INH THU (7) mesoporous materials, it was found that changing the DES concentration has a large effect on the mesoporosity, and under the same conditions the order of the mesoporous materials can be increased by increasing the DES concentration from 2mL to 5mL, as the first peak of INH THU (7) is stronger, and the interplanar spacing d was 97.84, which was larger than that of INH THU (6). However, by comparing INH THU (3) and (4), it was found that increasing DES too much during synthesis resulted in a decrease in the intensity of the reflections, especially the first reflections. The small angle X-ray diffraction pattern of INH THU (4) synthesized in the presence of 2mL DES showed three well resolved peaks with intensities higher than that of INH THU (3) synthesized in the presence of 10mL DES. From the small angle X-ray diffraction patterns of INH THU (2) and (3), it can be seen that under the same conditions, the use of higher acid (e.g., HCl) concentrations in the synthesis process favors the formation of well-ordered materials, such that the reflection at 1.5 ° to 2 ° at 2 θ is not resolved in the presence of INH THU (2) synthesized in the presence of a lower HCl concentration of 110 mL. Furthermore, the use of higher concentrations of TEOS and DES during synthesis may not provide ordered mesoporous materials as can be demonstrated by comparing the small angle X-ray diffraction patterns of the INH THU (1), (6) and (7) materials. The combination of the above facts shows that proper component distribution is crucial for obtaining ordered mesoporous materials. Further, the pH of the mixture also has a large influence on the structural properties of the material. As shown in FIG. 3, in the case of the synthesis of INHTHU (8), three ordered peaks were observed when the pH was increased to about 8, whereas in the case of the synthesis of INHTHU (9), the intensity of the first peak and the other two peaks was decreased at lower pH values of about 6.2 to 6.4, which indicates that the order degree of the mesoporous material obtained at the lower pH values was decreased. It should be noted that the DES concentration, the acid (e.g., HCl) concentration, and the TEOS concentration described in this paragraph are based on the total amount of each raw material component, and it is understood that the more the DES addition amount, the acid addition amount at a fixed concentration, and the TEOS addition amount, the larger the ratio of the three addition amounts in each raw material ratio.

FIGS. 4 to 13 are nitrogen adsorption-desorption isotherms of the synthesized mesoporous samples INH THU (1), INH THU (2), INH THU (3), INH THU (4), INH THU (5), INH THU (6), INH THU (7), INH THU (8), INH THU (9), and INH THU (10) in this order, and the specific surface areas (S) of the respective samples_BET) Total pore volume, average pore diameter andBJH pore size as shown in table 1, all samples showed type IV isotherms according to IUPAC classification, which correlates with their mesostructures having different hysteresis loops. Among them, the samples INH THU (1) and INH THU (3) to (10) had almost vertical and H1-like hysteresis loops, and were of the mesoporous type. The sharp change as capillary condensation in the relative pressure range of 0.6-0.85 indicates the order of the mesoporous structure of the samples INH THU (1) and INH THU (3) to (10). As can be seen from the isotherms of the samples INH THU (8), (9) and (10), increasing the pH of the reaction solution to 8 is advantageous for forming the mesoporous structure and improving the order of the mesoporous structure. This is also confirmed by the small angle X-ray diffraction results, as described above. As shown in Table 1, at a lower pH of about 4.4 to 4.6, the INH THU (10) sample showed lower surface area, total pore volume and average pore diameter, respectively, as compared with the INH THU (8) and INH THU (9) samples, which were 564.5m in this order²/g、0.53cm³G and 3.73 nm. With reference to fig. 11-13, the sharpness of the capillary condensation/evaporation step on the adsorption isotherms of samples INH THU (8) and INH THU (9) confirms that these samples have uniform mesopore size and highly ordered mesostructure, however, keeping other conditions unchanged, the capillary condensation/evaporation step on the adsorption isotherm of sample INH THU (10) synthesized at low pH of about 4.5 is not sharp; as can be seen from FIG. 11, the adsorption isotherm of the sample INH THU (8) was synthesized at pH 8, the capillary condensation step was shifted almost toward the higher relative pressure, the height increase indicating an increase in the total pore volume and pore diameter of the sample INH THU (8), and as shown in Table 1, the samples INH THU (8) and INH THU (9) showed 750.7m each²G and 752.5m²Higher surface area per g, even higher than 638m surface area synthesized by conventional hydrothermal method²SBA-15 in g. One more interesting result presented in table 1 is that the pore decimeter value on the desorption branch of the isotherms of samples INH THU (8) and (9) is 17nm, much higher than the mesoporous materials reported in the literature.

From the isotherm of the sample INH THU (5), it was found that the use of NaOH solution having a concentration of 6mol/L accelerates the condensation step to form a mesoporous material having a good structure. On the adsorption isotherm, as shown in FIG. 8The capillary condensation step is steep, indicating the order of the mesostructure of the sample INH THU (5). As shown in Table 1, the specific surface area, the total pore volume and the average pore diameter of the sample INH THU (5) were 402.75m²/g、1.09cm³G and 10.81 nm. By comparing the samples INH THU (2) and (3), it can be seen that a better mesoporous structure can be formed during the synthesis using a higher concentration of HCl solution. Under the synthesis conditions of sample INH THU (2), the capillary condensation step gradually moved to the direction of higher relative pressure, and its height increased by decreasing the concentration of HCl solution, which reflects the increase in pore volume and pore diameter. As listed in Table 1, the total pore volume and the average pore diameter of the sample INH THU (2) were 2.06cm, respectively³G and 13.52 nm. According to the isotherm of the sample INH THU (2), the hysteresis loops are no longer parallel, indicating the presence of a disordered mesoporous structure. This result is in good agreement with the small angle X-ray diffraction results discussed above.

The DES concentration had a large effect on the physical properties of the synthesized samples. The isotherms of the sample INH THU (6) shown in fig. 9 and the sample INH THU (7) shown in fig. 10 show hysteresis loops of type H1 associated with the presence of mesopores. The adsorption branch comprises a low slope region associated with multi-layer adsorption on the pore walls, followed by pore condensation in the mesopores, and finally ending with a plateau region, which indicates that the mesopores are completely filled and the macropores are limited or absent. As shown in fig. 9 and 10, the capillary condensation step is slightly shifted to the higher relative pressure and its height increases as the DES concentration increases from 2mL to 5mL, resulting in an increase in pore volume and diameter. In combination with the data shown in table 1, samples INH THU (6) and INH THU (7) exhibited nearly the same surface area, however, both the total pore volume and the average pore diameter of sample INH THU (7) were significantly higher than sample INH THU (6), which is in good agreement with the small angle X-ray diffraction results discussed above.

TABLE 1 physical Properties of mesoporous silica Material

Note: the specific surface area is such thatUsing the BET method at relative pressure (p/p)₀) Calculated under 0.05-0.3; the total pore volume is based on the relative pressure (p/p)₀) Calculated for an adsorption capacity of 0.99; the BJH aperture is estimated by a BJH method according to the isotherms of the adsorption branch and the desorption branch (numbers in brackets correspond to the desorption branch).

2. Evaluation of the thermal stability of the synthetic materials

Thermogravimetric analysis (TGA) was performed on the samples synthesized in examples 1, 2, 5, 6, 15, 16.

The samples synthesized in examples 1, 2, 5, 6, 15, and 16 were placed in a thermogravimetric analyzer (TGA) and the thermal decomposition temperature was studied. The test procedure includes: 1. selecting nitrogen as sample gas and purge gas, wherein the total flow rate is 100 mL/min; 2. selecting an initial temperature of 30 ℃ and keeping for 15 minutes; 3. the temperature was raised to 600 ℃ or 800 ℃ at a heating rate of 10 ℃/min. The TG curves of the materials obtained in examples 1, 2, 5, 6, 15 and 16 are shown in FIGS. 14 to 16. From the TGA results, it can be seen that the calcined INH THU material exhibits excellent thermal stability with negligible weight loss by increasing the temperature, even better than the case of SBA-15 synthesized by conventional hydrothermal method reported in the literature with weight loss as high as 7%. For the INH THU precursor material which was not calcined after synthesis, the copolymer P123 started to degrade around 200 ℃ and for the adsorbent with a TEPA loading of 50% (TEPA (50%)/INH THU, two weight loss phases were observed, a first weight loss phase being observed below a temperature of 130 ℃ mainly due to moisture and pre-adsorbed CO₂Release of (1); the second weight loss is a faster decomposition phase observed in the temperature range of 130-600 ℃, and the rapid weight loss of the adsorbent is mainly caused by decomposition combustion and volatilization of TEPA molecules immersed in the mixed carrier. Wherein Table 2 shows the actual amine loading of the adsorbents (TEPA (50%)/INH THU) obtained from thermogravimetric analysis, as shown in Table 2, the actual weight loss rates of TEPA (50%)/INH THU (1), TEPA (50%)/INH THU (3), and TEPA (50%)/INH THU (8) were 47.68%, 47.62%, and 48.20% in that order, and in fact, these weight loss rates were the actual loading of TEPA into or to the mixed support.

3. CO for synthetic materials₂Evaluation of Capture Performance and cycling stability

Samples synthesized in examples 1, 2, 5, 6, 15, 16 were subjected to a Thermal Gravimetric Analyzer (TGA) for cycle stability testing and CO₂And (5) testing the adsorption performance.

3.1TGA on CO₂The procedure for adsorption performance testing included: 1. selecting nitrogen as sample gas; 2. heating from room temperature to 105 ℃ at the speed of 10 ℃/min; 3. keeping the temperature for 60 minutes; 4. reducing the temperature from 105 ℃ to 75 ℃ at a rate of 10 ℃/min; 5. selecting carbon dioxide as a sample gas; 6. keeping the temperature for 180 minutes; the concentration of carbon dioxide absorbed at 75 ℃ was 15%, the balance being nitrogen.

CO₂The absorption is expressed as CO adsorbed per gram of adsorbent₂Weight of (g) of (g CO)₂Per g adsorbent), amine efficiency is defined as adsorbed CO₂Divided by the amount of amine present (mol CO) obtained by elemental analysis₂/mol N)。CO₂The results of the adsorption performance test are shown in table 2 and fig. 17 to 19. Wherein, the CO of the synthesized adsorbent samples TEPA (50%)/INH THU (1), TEPA (50%)/INH THU (3), TEPA (50%)/INH THU (8) are shown in sequence in FIGS. 17-19₂The original plot is taken with the left Y-1 axis being the weight axis and the right Y-2 axis being the temperature axis. Table 2 shows the CO at 75 deg.C and 1atm for the synthesized sorbent samples₂The amount of absorption. As can be seen, the samples TEPA (50%) INH THU (1), TEPA (50%) INH THU (3), TEPA (50%) INH THU (8) are CO₂The adsorption amounts were 131.2mg/g, 155.5mg/g, and 152.0mg/g, respectively. The elemental analysis data in table 2 show that the sample obtained by dipping has high N content, which can reach 16-17%. Sample TEPA (50%) INH THU (3) showed 0.31(mol CO) compared to the other samples₂Per mol N), TEPA (50%) INH THU (3) exhibits higher CO₂The absorption capacity.

TABLE 2 CO of TEPA functionalized sorbents at 75 deg.C and 1atm₂Absorption capacity

3.2 Thermo Gravimetric Analysis (TGA) of CO₂The procedure of the cycle test includes: 1. selecting nitrogen as sample gas; 2. heating from room temperature to 105 ℃ at the speed of 10 ℃/min; 3. keeping the temperature for 60 minutes; 4. reducing the temperature from 105 ℃ to 75 ℃ at a rate of 10 ℃/min; 5. selecting carbon dioxide as a sample gas; 6. keeping the temperature for 10 minutes; 7. selecting nitrogen as sample gas; 8. heating to 100 ℃ at the speed of 10 ℃/min; 10. keeping the temperature for 10 minutes; 11. the cycle is 10 times from the fifth step. The concentration of carbon dioxide absorbed at 75 ℃ was 15%, the balance being nitrogen.

FIGS. 20-22 show the CO of the synthesized sorbent samples TEPA (50%)/INH THU (1), TEPA (50%)/INH THU (3), TEPA (50%)/INH THU (8) in that order₂Graph of absorption capacity (left Y-1 axis) and adsorption index (right Y-2 axis) as a function of increasing number of cycles; FIGS. 23-25 show in sequence raw plots of CO2 cycle adsorption-desorption performance for synthetic adsorbent samples TEPA (50%)/INH THU (1), TEPA (50%)/INH THU (3), TEPA (50%)/INH THU (8), with the left-hand Y-1 axis being the weight axis and the right-hand Y-2 axis being the temperature axis. Excellent regeneration performance of the adsorbent is very essential for the adsorbent during long-term adsorption-desorption operation, and therefore, evaluation of stability of the TEPA-functionalized INH THU during adsorption-desorption cycles is an important index for judging whether INH THU is suitable as a carrier for immobilizing TEPA. Wherein the adsorption index is CO of the regenerated adsorbent and the fresh adsorbent in the first cycle₂The percent capture capacity, 100% adsorption index, means that the adsorbent did not degrade at all during the cycling test. From the results shown in FIGS. 20 to 22, the CO of each adsorbent sample₂The adsorption index is not lower than 95% after 10 cycles, and specifically, the absorption indexes of samples TEPA (50%)/INH THU (1), TEPA (50%)/INH THU (3) and TEPA (50%)/INH THU (8) after 10 cycles are respectively about 99%, 95% and 97%, which show excellent cycle performance. These results show that the adsorbent obtained by loading TEPA amine on the silica mesoporous material carrier synthesized by the ion-non-hydrothermal method according to the above embodiment of the present invention has high thermal stability, and the obtained adsorbent can effectively adsorb CO₂And also has better cycle stability.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A method for preparing a mesoporous silica material, comprising:

2. The method of claim 1, wherein step (1) satisfies at least one of the following conditions:

the solid-to-liquid ratio of the copolymer P123 to the acid is (3-4.45) g: (60-140) mL, wherein the concentration of hydrogen ions in the acid is 1-2 mol/L;

the acid includes at least one selected from hydrochloric acid, nitric acid and sulfuric acid;

the surfactant is copolymer P123.

3. The method of claim 2, wherein at least one of the following conditions is satisfied:

in the step (2), the mol ratio of choline chloride to urea in the choline chloride-urea ionic liquid is 1: 2;

in the step (2), the solid-to-liquid ratio of the copolymer P123 to the choline chloride-urea ionic liquid is (3-4.45) g: (2-10) mL;

in the step (3), the silicon source is silicate or tetraethyl orthosilicate (TEOS);

in the step (3), the solid-to-liquid ratio of the copolymer P123 to the silicon source is (3-4.45) g: (10-14) mL.

4. A method according to any one of claims 1 to 3, wherein at least one of the following conditions is satisfied:

in the step (4), adjusting the pH value of the suspension to 6.2-8 by using ammonia gas or alkali liquor;

in the step (4), the alkali liquor is ammonia water and/or a sodium hydroxide solution, the mass concentration of the ammonia water is 25-28 wt%, and the concentration of the sodium hydroxide solution is 5.5-6.5 mol/L;

in the step (5), the frequency of the ultrasonic reaction is 36-40kHz, and the time is 1 +/-0.1 h;

in the step (5), the ultrasonic reaction is carried out under the condition of water bath stirring, and the temperature of the water bath is 35-37 ℃;

in the step (6), the calcining treatment temperature is 550 +/-5 ℃ and the time is 6 +/-0.2 h.

5. A silica mesoporous material prepared by the method of any one of claims 1 to 4.

6. The method for preparing the mesoporous silica material according to any one of claims 1 to 4 and/or the use of the mesoporous silica material according to claim 5 in the fields of adsorbents and catalysts.

7. A mesoporous silica adsorbent, characterized by comprising a carrier, wherein the carrier is the mesoporous silica material according to claim 5 or the mesoporous silica material prepared by the method according to any one of claims 1 to 4.

8. The mesoporous silica adsorbent according to claim 7, further comprising: an amine supported on the support.

9. The mesoporous silica adsorbent according to claim 8, wherein the amine is tetraethylenepentamine, and the mass ratio of the amine to the carrier is 1: 1.

10. A method for preparing the mesoporous silica adsorbent according to any one of claims 7 to 9, comprising:

mixing amine and a volatile organic solvent to obtain a mixed solution;