CN114011381A - Preparation method of spherical mesoporous carbon with adjustable particle size - Google Patents

Abstract

The invention discloses a preparation method of spherical mesoporous carbon with adjustable particle size, belonging to the technical field of new materials. By utilizing the preparation method, the grain diameter of the prepared spherical mesoporous carbon can be adjusted by adjusting the using amount of ethanol and the self-assembly temperature, and the preparation method is suitable for different application occasions.

Description

Preparation method of spherical mesoporous carbon with adjustable particle size

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a preparation method of spherical mesoporous carbon with adjustable particle size.

Background

The serious environmental and human health hazards of Volatile Organic Compounds (VOCs) have raised concerns worldwide. Fossil fuel combustion, petrochemicals, paints, coatings, pesticides, plastics and other industrial processes cause the emission of a large portion of man-made VOCs. Most VOCs have the functions of stink and carcinogenesis, and cause the environment of human health thingsMoreover, most VOCs are inflammable and explosive, which brings serious insecurity to production enterprises. In addition to the hazards, VOCs can also cause secondary pollution, including the presence of atoms O, O dissociated from the atmosphere under UV irradiation₃OH and H₂O and the like react to generate photochemical smog with strong oxidizing property, thereby bringing greater harm to the health of human beings.

Adsorption is considered to be one of the effective VOCs abatement strategies due to its cost-effective, simple and low energy consumption characteristics. In the prior art, common adsorbing materials include porous carbon materials and the like. The porous carbon material refers to a material with different pore channel structures, and can be divided into the following components according to the pore size: microporous carbon materials (d is less than 2nm), mesoporous carbon materials (d is more than 2nm and less than 50nm) and macroporous carbon materials (d is more than 50 nm). Since the first synthesis of M41S mesoporous materials by Mobil corporation in 1992, mesoporous materials have attracted much attention due to their unique characteristics, such as uniform pore structure, good thermal and chemical stability, and large specific surface area.

Research shows that the particle size of mesoporous carbon significantly affects adsorption capacity. Raposo et al (2009) studied the adsorption behavior of activated carbon with a particle size of 428-1600 μm on methylene blue, and the results show that the adsorption capacity and the particle size are in a linear relationship.

However, the relationship between the particle size of the spherical mesoporous carbon and the ability of the spherical mesoporous carbon to adsorb VOCs is not clear, and there is no mature preparation technology capable of controlling the particle size of the spherical mesoporous carbon to adsorb VOCs.

Disclosure of Invention

In order to solve at least one of the above technical problems, the technical solution adopted by the present invention is as follows:

the invention provides a preparation method of spherical mesoporous carbon with adjustable particle size, which comprises the steps of preparing a precursor solution by using a triblock copolymer as a template agent, using resol as a carbon source and using ethanol as a solvent, dropping the precursor solution into water at 85-90 ℃ for self-assembly to obtain a prepolymer, and further heating and carbonizing to obtain the spherical mesoporous carbon, wherein the particle size of the spherical mesoporous carbon is adjusted by changing the using amount of ethanol and/or the self-assembly temperature.

In the present invention, the particle size of the spherical mesoporous carbon refers to the diameter of the spherical mesoporous carbon.

In some embodiments of the invention, the resole is prepared by:

melting phenol at 38-40 deg.C, adding 0.5mol/L sodium hydroxide solution, stirring, and adding 37% formaldehyde solution; heating to 70-75 deg.C, stirring, condensing, refluxing, cooling to room temperature, and adjusting pH to 7.0 with hydrochloric acid solution; and then distilling under reduced pressure at 45-50 ℃ to remove water in the mixture to obtain the resol.

In some embodiments of the present invention, the preparation method specifically comprises the following steps:

s1, dissolving the resol in ethanol to prepare a resol-ethanol solution with the resol mass fraction of 40-50%;

s2, dissolving the triblock copolymer in absolute ethyl alcohol at 35 ℃ to prepare a 60-70% solution, uniformly stirring, adding the solution into the resol-ethanol solution obtained in the step S1 according to the proportion of 25%, continuously stirring to obtain a uniformly mixed precursor solution, and dropping the precursor solution into water at 85-90 ℃ to form spherical gel; then transferring the spherical gel to a drying oven with the temperature of 100 ℃ for thermal polymerization for 24 hours to obtain a prepolymer;

s3, placing the prepolymer obtained in the step S2 in an atmosphere furnace, heating to 350 ℃ at the speed of 1 ℃/min under the protection of nitrogen, roasting for 5 hours, and heating to 900 ℃ at the speed of 1 ℃/min, and roasting for 4 hours to obtain the spherical mesoporous carbon.

In the present invention, the triblock copolymer is one selected from the group consisting of P123, F108 and F127.

In some embodiments of the invention, in step S1, the resole and Cr (NO) are mixed₃)₃·9H₂Mixing and dissolving O in ethanol according to the C, Cr molar ratio of 20-40: 1 to prepare a chromium nitrate-containing resol-ethanol solution with the resol mass fraction of 40-50%.

In other embodiments of the present invention, the method further comprises:

s4, immersing the spherical mesoporous carbon obtained in the step S3 in Cr (NO)₃)₃In solution and dried.

The invention has the advantages of

Compared with the prior art, the invention has the following beneficial effects:

the spherical mesoporous carbon prepared by the preparation method has very good adsorption capacity on various VOCs, and can be used for preparing air purifiers.

By utilizing the preparation method, the grain diameter of the prepared spherical mesoporous carbon can be adjusted by adjusting the using amount of ethanol and the self-assembly temperature, and the preparation method is suitable for different application occasions.

Drawings

Fig. 1 shows spherical mesoporous carbon prepared in example 1 of the present invention.

Fig. 2 shows the particle size distribution of spherical mesoporous carbon prepared in example 1 of the present invention.

Fig. 3 shows a nitrogen adsorption/desorption curve of spherical mesoporous carbon prepared in example 1 of the present invention.

FIG. 4 shows the static adsorption curve of the spherical mesoporous carbon prepared in example 1 of the present invention to formaldehyde.

FIG. 5 shows the static adsorption curves of p-toluene, benzene, cyclohexane and ethyl acetate for spherical mesoporous carbon prepared in example 1 of the present invention.

FIG. 6 shows the effect of the mass fraction of triblock copolymer in the triblock copolymer ethanol solution on the particle size of the spherical mesoporous carbon prepared.

Fig. 7 shows the effect of the mass fraction of resole in the resole ethanol solution on the particle size of the spherical mesoporous carbon produced.

Fig. 8 shows the effect of self-induced assembly temperature on the particle size of the prepared spherical mesoporous carbon.

Detailed Description

Unless otherwise indicated, implied from the context, or customary in the art, all parts and percentages herein are by weight and the testing and characterization methods used are synchronized with the filing date of the present application. Where applicable, the contents of any patent, patent application, or publication referred to in this application are incorporated herein by reference in their entirety and their equivalent family patents are also incorporated by reference, especially as they disclose definitions relating to synthetic techniques, products and process designs, polymers, comonomers, initiators or catalysts, and the like, in the art. To the extent that a definition of a particular term disclosed in the prior art is inconsistent with any definitions provided herein, the definition of the term provided herein controls.

The numerical ranges in this application are approximations, and thus may include values outside of the ranges unless otherwise specified. A numerical range includes all numbers from the lower value to the upper value, in increments of 1 unit, provided that there is a separation of at least 2 units between any lower value and any higher value. For example, if a compositional, physical, or other property (e.g., molecular weight, melt index, etc.) is recited as 100 to 1000, it is intended that all individual values, e.g., 100, 101, 102, etc., and all subranges, e.g., 100 to 166, 155 to 170, 198 to 200, etc., are explicitly recited. For ranges containing a numerical value less than 1 or containing a fraction greater than 1 (e.g., 1.1, 1.5, etc.), then 1 unit is considered appropriate to be 0.0001, 0.001, 0.01, or 0.1. For ranges containing single digit numbers less than 10 (e.g., 1 to 5), 1 unit is typically considered 0.1. These are merely specific examples of what is intended to be expressed and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application.

When used with respect to chemical compounds, the singular includes all isomeric forms and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively) unless expressly specified otherwise. In addition, unless explicitly stated otherwise, the use of the terms "a", "an" or "the" are intended to include the plural forms thereof.

The terms "comprising," "including," "having," and derivatives thereof do not exclude the presence of any other component, step or procedure, and are not intended to exclude the presence of other elements, steps or procedures not expressly disclosed herein. To the extent that any doubt is eliminated, all compositions herein containing, including, or having the term "comprise" may contain any additional additive, adjuvant, or compound, unless expressly stated otherwise. Rather, the term "consisting essentially of … …" excludes any other components, steps or processes from the scope of any of the terms hereinafter recited, insofar as such terms are necessary for performance. The term "consisting of … …" does not include any components, steps or processes not specifically described or listed. Unless explicitly stated otherwise, the term "or" refers to the listed individual members or any combination thereof.

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments.

Examples

The following examples are used herein to demonstrate preferred embodiments of the invention. It will be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function in the invention, and thus can be considered to constitute preferred modes for its practice. Those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit or scope of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs and the disclosures and references cited herein and the materials to which they refer are incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

The experimental procedures in the following examples are conventional unless otherwise specified. The instruments used in the following examples are, unless otherwise specified, laboratory-standard instruments; the test materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified.

Example 1 preparation of spherical mesoporous carbon

The present implementation provides a method for preparing spherical mesoporous carbon with optimized parameters.

1. Preparation of resol

Melting 40g of phenol at 38 ℃, adding the melted phenol into 60mL of 0.5mol/L sodium hydroxide solution, stirring uniformly, and adding 100mL of 37% formaldehyde solution; heating to 75 ℃, then continuing stirring for 0.6h, condensing and refluxing to cool the mixture to room temperature, and adjusting the pH value to 7.0 by using 2mol/L hydrochloric acid solution; then, the mixture was distilled under reduced pressure at 48 ℃ to remove water from the mixture, thereby obtaining a resol resin.

2. Preparation of resol-chromic nitrate-ethanol solution

Mixing resol and Cr (NO) at C, Cr mol ratio of 33:1₃)₃·9H₂And mixing and dissolving the O in ethanol to prepare a resol-chromium nitrate-ethanol solution with the mass fraction of the resol being 48%.

3. Preparation of mesoporous prepolymer

Dissolving 34.5g of triblock copolymer P108 in 50mL of absolute ethyl alcohol at the temperature of 35 ℃, uniformly stirring (about 20min), adding the obtained resol-chromium nitrate-ethanol solution according to the proportion of 25%, continuously stirring to obtain uniformly mixed precursor solution, and dripping the precursor solution in water at the temperature of 90 ℃ to form spherical gel; then transferring the spherical gel to an oven dried at 100 ℃ for thermal polymerization for 24h to obtain a prepolymer.

4. Roasting carbonization

And placing the obtained prepolymer in an atmosphere furnace, heating to 450 ℃ at the speed of 1 ℃/min under the protection of nitrogen, roasting for 3h, and heating to 850 ℃ at the speed of 6 ℃/min, and roasting for 3h to obtain the spherical mesoporous carbon.

The spherical mesoporous carbon prepared by the above scheme is detected to have uniform particle size, as shown in fig. 1, and the median of the particle size (diameter) is 4.6mm (as shown in fig. 2).

Example 2 characterization of spherical mesoporous carbon

In order to confirm that the spherical mesoporous carbon prepared by the preparation method of the spherical mesoporous carbon in example 1 of the invention has excellent characteristics, the spherical mesoporous carbon prepared in example 1 is characterized.

The spherical mesoporous carbon pore structure is determined by 3H-2000Ps2 specific surface and pore size analyzer produced by Beijing Beschild instruments science and technology Co., Ltd, nitrogen is used as adsorption medium, and the pressure is 77K and the relative pressure (P/P)₀) Is 10^-3Nitrogen adsorption measurements were performed under conditions of-1.0. Before testing, the spherical mesoporous carbon was degassed at 300 ℃ for 12 h.

Calculating the specific surface area by using a BET model; calculating the specific surface area of the micropore by using a t-plot equation; the pore volume is calculated from the adsorption amount at a relative pressure of 0.995; the calculation of the aperture uses the BJH model.

As shown in fig. 3, it can be seen that the nitrogen adsorption/desorption isotherms of the prepared spherical mesoporous carbon are both typical class IV isotherms and H2 hysteresis loops, specifically, the spherical mesoporous carbon undergoes single-layer adsorption and multi-layer adsorption in a low-pressure environment, and the adsorption capacity rapidly increases with the increase of pressure, which can be attributed to capillary condensation, which is a typical adsorption phenomenon of mesoporous materials. Moreover, the hysteresis loops of the spherical mesoporous carbon are all generated under the relative pressure of 0.5-0.7, which indicates that the spherical mesoporous carbon has uniform mesoporous channels.

The characteristics of the spherical mesoporous carbon, such as pore diameter, specific surface area and pore volume, are shown in table 1:

TABLE 1 characterization of spherical mesoporous carbons prepared in example 1

As can be seen from the data in table 1, the spherical mesoporous carbon prepared in example 1 has the most uniform pore diameter, the very small standard deviation, and the large pore volume, micropore volume and specific surface area, indicating that the adsorption capacity is strong.

Example 3 effect of adsorbing Formaldehyde by spherical mesoporous carbon

The adsorption experiment was performed on an Intelligent Gravity Analyzer (IGA) model 002, by Hiden corporation, uk, and the apparatus consisted essentially of a test system, a molecular pump, and an analysis system.

Before the adsorption experiment, 50-80 mg of spherical mesoporous carbon is degassed under vacuum at 120 ℃. During the test, the vapors of the VOCs gradually enter the test system, and the system pressure is increased until the saturated vapor pressure of the VOCs.

In this example, the inventors used the spherical mesoporous carbon prepared in example 1 of the present invention to adsorb formaldehyde at room temperature, so as to obtain the adsorption capacity for formaldehyde.

As shown in fig. 4, the adsorption curve of the spherical mesoporous carbon prepared in example 1 for formaldehyde substantially conforms to the type I adsorption curve, i.e., monomolecular layer adsorption. And the adsorption performance is higher and reaches 1.91 mmol/g.

Example 4 adsorption of VOCs by spherical mesoporous carbon

To investigate the adsorption effect of the spherical mesoporous carbon prepared in example 1 on VOCs, the inventors further tested the adsorption capacity of the spherical mesoporous carbon prepared in example 1 on toluene, benzene, cyclohexane and ethyl acetate at room temperature.

As shown in FIG. 5, the adsorption capacities of the spherical mesoporous carbon prepared in example 1 for toluene, benzene, cyclohexane and ethyl acetate in VOCs reached 2.33mmol/g, 2.86mmol/g, 4.12mmol/g and 7.99mmol/g, respectively.

Therefore, the spherical mesoporous carbon prepared in example 1 has very good adsorption capacity for various VOCs, and can be used for preparing air purifiers.

Example 5 particle size control during preparation of spherical mesoporous carbon

In order to adapt to different application scenarios, the particle size of the spherical mesoporous carbon needs to be controlled, and for this reason, the inventors have made a series of attempts to unexpectedly find that the particle size of the prepared spherical mesoporous carbon can be controlled by changing some parameters of the preparation method of example 1. The parameters of the adjustment are shown in table 2:

TABLE 2 adjustment of preparation parameters for spherical mesoporous carbon

The influence of the mass fraction of the triblock copolymer in the triblock copolymer ethanol solution on the spherical mesoporous carbon is the largest, and the particle size of the prepared spherical mesoporous carbon is reduced along with the increase of the mass fraction of the triblock copolymer, namely the reduction of the ethanol dosage (as shown in figure 6), so that the particle size of the prepared spherical mesoporous carbon can be controlled by controlling the mass fraction of the triblock copolymer.

The influence of the mass fraction of the resole in the resole ethanol solution on the spherical mesoporous carbon shows the same trend, that is, the particle size of the prepared spherical mesoporous carbon becomes smaller with the increase of the mass fraction of the resole, that is, the reduction of the ethanol dosage (as shown in fig. 7), but the trend is not obvious.

In terms of temperature, as shown in fig. 8, the temperature has little influence on the median value of the particle size of the spherical mesoporous carbon, but when the temperature is lower than 85 ℃, the standard deviation of the particle size is large, which indicates that the obtained spherical mesoporous carbon has large fluctuation of the particle size range and is not uniform enough.

All documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.

Claims (6)

1. The preparation method of the spherical mesoporous carbon with the adjustable particle size is characterized in that a triblock copolymer is used as a template agent, a resol is used as a carbon source, ethanol is used as a solvent to prepare a precursor solution, the precursor solution is dripped into water with the temperature of 85-90 ℃ for self-assembly to obtain a prepolymer, and the spherical mesoporous carbon is further prepared by heating and carbonizing, wherein the particle size of the spherical mesoporous carbon is adjusted by changing the using amount of the ethanol and/or the self-assembly temperature.

2. The method for preparing spherical mesoporous carbon with adjustable particle size according to claim 1, wherein the resol is prepared by the following steps:

melting phenol at 38-40 deg.C, adding 0.5mol/L sodium hydroxide solution, stirring, and adding 37% formaldehyde solution; heating to 70-75 deg.C, stirring, condensing, refluxing, cooling to room temperature, and adjusting pH to 7.0 with hydrochloric acid solution; and then distilling under reduced pressure at 45-50 ℃ to remove water in the mixture to obtain the resol.

3. The method for preparing spherical mesoporous carbon with adjustable particle size according to claim 2, wherein the method specifically comprises the following steps:

s1, dissolving the resol in ethanol to prepare a resol-ethanol solution with the resol mass fraction of 40-50%;

s2, dissolving the triblock copolymer in absolute ethyl alcohol at 35 ℃ to prepare a 60-70% solution, uniformly stirring, adding the solution into the resol-ethanol solution obtained in the step S1 according to the proportion of 25%, continuously stirring to obtain a uniformly mixed precursor solution, and dropping the precursor solution into water at 85-90 ℃ to form spherical gel; then transferring the spherical gel to a drying oven with the temperature of 100 ℃ for thermal polymerization for 24 hours to obtain a prepolymer;

s3, placing the prepolymer obtained in the step S2 in an atmosphere furnace, heating to 350 ℃ at the speed of 1 ℃/min under the protection of nitrogen, roasting for 5 hours, and heating to 900 ℃ at the speed of 1 ℃/min, and roasting for 4 hours to obtain the spherical mesoporous carbon.

4. The method for preparing spherical mesoporous carbon with adjustable particle size according to any one of claims 1 to 3, wherein the triblock copolymer is selected from one of P123, F108 and F127.

5. The spherical mesoporous carbon with adjustable particle size according to claim 3Is characterized in that, in step S1, a resol and Cr (NO) are mixed₃)₃·9H₂Mixing and dissolving O in ethanol according to the C, Cr molar ratio of 20-40: 1 to prepare a chromium nitrate-containing resol-ethanol solution with the resol mass fraction of 40-50%.

6. The method for preparing spherical mesoporous carbon with adjustable particle size according to claim 3, further comprising:

s4, immersing the spherical mesoporous carbon obtained in the step S3 in Cr (NO)₃)₃In solution and dried.

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