CN113578260A - Preparation method of fly ash-based MCM-41 mesoporous molecular sieve and product thereof - Google Patents

Preparation method of fly ash-based MCM-41 mesoporous molecular sieve and product thereof Download PDF

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CN113578260A
CN113578260A CN202110837237.5A CN202110837237A CN113578260A CN 113578260 A CN113578260 A CN 113578260A CN 202110837237 A CN202110837237 A CN 202110837237A CN 113578260 A CN113578260 A CN 113578260A
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fly ash
molecular sieve
mcm
mesoporous molecular
preparation
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史可人
姚惠琴
孔月月
薛屏
李鹏
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Ningxia University
Ningxia Medical University
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Ningxia Medical University
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Abstract

The embodiment of the application provides a preparation method of a fly ash-based MCM-41 mesoporous molecular sieve, which comprises the following steps: (1) pickling the fly ash; (2) mixing the washed fly ash with an aqueous solution of sodium hydroxide, desiliconizing and filtering to obtain a desiliconized solution; (3) adding deionized water and methanol into CTAB, dropwise adding the desiliconized solution, mixing, then adjusting the pH, aging, crystallizing and calcining the obtained solution to obtain the fly ash-based MCM-41 mesoporous molecular sieve, wherein the molar ratio of silicon to CTAB in the obtained solution is 1 (0.0010-0.0045). The coal ash-based MCM-41 mesoporous molecular sieve prepared by the preparation method has large specific surface area, large pore volume and narrow pore size distribution, has a hexagonal mesoporous structure, and can be effectively applied to the field of wastewater treatment.

Description

Preparation method of fly ash-based MCM-41 mesoporous molecular sieve and product thereof
Technical Field
The application relates to the technical field of comprehensive utilization of fly ash, in particular to a preparation method of a fly ash-based MCM-41 mesoporous molecular sieve and a product thereof.
Background
The resource of rich coal, lean oil and less gas greatly emphasizes fossil energy in China on coal, the stockpiling amount of fly ash which is a main solid waste discharged in the coal burning process is increased year by year, a large amount of land resources are occupied, and the harm is brought to the ecological environment and the human health, but at present, the fly ash is only applied to the admixture of building materials or the building backfill in China, the fly ash is only subjected to primary low-efficiency use, and compared with the situation that only about 20% of the fly ash is taken as the building materials abroad, the high utilization value of the fly ash is not really exerted. Therefore, the application of fly ash is being shifted from the field of building materials such as cement with low added value to the field of high added value.
In recent years, with the rapid development of the dye industry, a large amount of organic polluted wastewater enters the water environment, so that the water pollution condition is increasingly aggravated, a plurality of technologies are used for water treatment, but the adsorption method is distinguished by the advantages of mature technology, simple equipment and process and the like. The MCM-41 mesoporous molecular sieve has wide application prospect in the field of wastewater treatment due to the excellent characteristics of large specific surface area, high porosity, narrow pore size distribution and the like, but is limited by the problems of high silicon source price, high preparation cost and the like, and cannot realize large-scale production. Therefore, the preparation of MCM-41 mesoporous molecular sieve from cheap and silicon-rich fly ash is the hot spot of current research.
Disclosure of Invention
The application aims to provide a preparation method of a fly ash-based MCM-41 mesoporous molecular sieve.
The first aspect of the application provides a preparation method of a fly ash-based MCM-41 mesoporous molecular sieve, which comprises the following steps:
(1) adding the fly ash into a hydrochloric acid aqueous solution, reacting for 2-4 h at 80-90 ℃, and filtering to obtain acid-washed fly ash;
(2) adding a sodium hydroxide aqueous solution into the acid-washed fly ash, desiliconizing for 5-6 h at the temperature of 90-100 ℃, and filtering to obtain a desiliconized solution;
(3) adding deionized water and methanol into Cetyl Trimethyl Ammonium Bromide (CTAB), dropwise adding the desiliconization solution, mixing for 2-3 h at 35-45 ℃, adjusting the pH to 9-11, aging the obtained solution for 3-4 h, crystallizing and calcining to obtain the fly ash-based MCM-41 mesoporous molecular sieve, wherein the molar ratio of silicon to CTAB in the obtained solution is 1 (0.0010-0.0045).
In a second aspect, the present application provides a fly ash-based MCM-41 mesoporous molecular sieve prepared by the preparation method provided herein.
According to the preparation method of the fly ash-based MCM-41 mesoporous molecular sieve, the fly ash is subjected to acid washing, so that the influence of other components on the preparation of the mesoporous molecular sieve is reduced to a certain extent, the silica-alumina ratio can be improved, and the reaction activity of the mesoporous molecular sieve can be improved. And the alkali-soluble desiliconization is adopted to replace the alkali-soluble desiliconization, so that the preparation energy consumption is reduced, and the desiliconization rate of the fly ash is improved. The simple hydrothermal method adopted by the preparation has the advantages of simple process, high system integration level, easiness in industrialization and the like. The coal ash-based MCM-41 mesoporous molecular sieve provided by the application has a large specific surface area, a large pore volume and a narrow pore size distribution, has a hexagonal mesoporous structure, and can be effectively applied to the field of wastewater treatment.
Of course, not all advantages described above need to be achieved at the same time in the practice of any one product or method of the present application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and it is also obvious for a person skilled in the art to obtain other embodiments according to the drawings.
FIG. 1 shows a fly ash-based MCM-41 mesoporous molecular sieve and an aminated and modified fly ash-based MCM-41 mesoporous molecular sieve (NH) in example 12-MCM-41) and PVP grafted fly ash based MCM-41 mesoporous molecular sieve (PVP-MCM-41).
FIG. 2 shows the molecular sieve NH of the fly ash-based MCM-41 mesoporous molecular sieve in example 12-infrared spectrogram of MCM-41 and PVP-MCM-41, curve (a) corresponding to MCM-41 and curve (b) corresponding to NH2-MCM-41, curve (c) corresponds to PVP-MCM-41.
FIG. 3 is SEM images of fly ash-based MCM-41 mesoporous molecular sieve in example 1 under different magnifications.
FIG. 4 shows the molecular sieve NH of the fly ash-based MCM-41 mesoporous molecular sieve in example 12TEM images of transmission electron microscope of MCM-41, PVP-MCM-41, FIG. 4 (a), (b), (c), (d) correspond to MCM-41, and (e) corresponds to NH2-MCM-41, (f) corresponds to PVP-MCM-41.
FIG. 5 shows the molecular sieve NH of the fly ash-based MCM-41 mesoporous molecular sieve in example 12-pore size distribution of MCM-41 and PVP-MCM-41.
FIG. 6 is a plot of the adsorption-desorption isotherm of nitrogen for the fly ash-based MCM-41 mesoporous molecular sieve of example 1.
FIG. 7 shows the molecular sieve NH of the fly ash-based MCM-41 mesoporous molecular sieve in example 12-MCM-41 and PVP-MCM-41 adsorption effect graph.
FIG. 8 is a TEM image of transmission electron microscope showing that PVP-MCM-41 in example 1 adsorbs lead ions.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the description herein are intended to be within the scope of the present disclosure.
The first aspect of the application provides a preparation method of a fly ash-based MCM-41 mesoporous molecular sieve, which comprises the following steps:
(1) adding the fly ash into a hydrochloric acid aqueous solution, reacting for 2-4 h at 80-90 ℃, and filtering to obtain acid-washed fly ash;
(2) adding a sodium hydroxide aqueous solution into the acid-washed fly ash, desiliconizing for 5-6 h at the temperature of 90-100 ℃, and filtering to obtain a desiliconized solution;
(3) adding deionized water and methanol into Cetyl Trimethyl Ammonium Bromide (CTAB), dropwise adding the desiliconization solution, mixing for 2-3 h at 35-45 ℃, adjusting the pH to 9-11, aging the obtained solution for 3-4 h, crystallizing and calcining to obtain the fly ash-based MCM-41 mesoporous molecular sieve, wherein the molar ratio of silicon to CTAB in the obtained solution is 1 (0.0010-0.0045).
In some embodiments of the first aspect of the present application, the concentration of the aqueous hydrochloric acid solution is 3mol/L to 4mol/L, and the ratio of the mass of the fly ash to the volume of the aqueous hydrochloric acid solution is 1 (9-11) g/mL.
In some embodiments of the first aspect of the present application, the aqueous sodium hydroxide solution has a concentration of 2mol/L to 2.5mol/L and the ratio of the mass of the acid-washed fly ash to the volume of the aqueous sodium hydroxide solution is 1 (14-16) g/mL.
In certain embodiments of the first aspect of the present application, the volume ratio of the desilication solution, the methanol and the deionized water is 1 (0.43-0.66) to (0.6-0.8).
In certain embodiments of the first aspect of the present application, the temperature of the crystallization is 95 ℃ to 105 ℃ and the time of the crystallization is 36h to 48 h.
In some embodiments of the first aspect of the present application, the temperature of the calcining is 550 ℃ to 600 ℃, the temperature increase rate of the calcining is 1 ℃/min to 3 ℃/min, and the time of the calcining is 6h to 7 h.
In the first aspect of the present applicationIn some embodiments, the fly ash-based MCM-41 mesoporous molecular sieve has a specific surface area of 910m2/g-950m2Per g, pore volume of 0.70cm3/g-0.90cm3(ii)/g, the average adsorption pore diameter is 5.58nm-5.80 nm.
In some embodiments of the first aspect of the present application, the method further comprises the steps of:
mass is taken as M1The fly ash-based MCM-41 mesoporous molecular sieve is added with M by mass23-aminopropyltriethoxysilane APTES and volume V1Stirring the dry toluene, condensing and refluxing the mixture for 5 to 7 hours at the temperature of between 105 and 115 ℃, and filtering the mixture to obtain the aminated and modified fly ash-based MCM-41 mesoporous molecular sieve, wherein M is1:M2:V1Is 1 (0.4-0.6) to 50-70 g/g/mL.
In some embodiments of the first aspect of the present application, the amination-modified fly ash-based MCM-41 mesoporous molecular sieve has a specific surface area of 710m2/g-750m2Per g, pore volume of 0.56cm3/g-0.81cm3(ii)/g, the average adsorption pore diameter is 5.24nm-5.45 nm.
In some embodiments of the first aspect of the present application, the method further comprises the steps of:
mass is taken as M3The amination modified fly ash-based MCM-41 mesoporous molecular sieve is added with M by mass4Polyvinylpyrrolidone PVP with mass M5Phosphorus pentoxide and volume V2Stirring the absolute ethyl alcohol at the temperature of between 75 and 80 ℃, carrying out condensation reflux for 20 to 28 hours, carrying out ultrasonic treatment for 15 to 25 minutes, and filtering to obtain the PVP grafted fly ash based MCM-41 mesoporous molecular sieve, wherein M is3:M4:M5:V21:1 (0.14-0.19) g/g/g/mL (30-38).
In some embodiments of the first aspect of the present application, the PVP grafted fly ash-based MCM-41 mesoporous molecular sieve has a specific surface area of 220m2/g-250m2Per g, pore volume of 0.38cm3/g-0.55cm3(ii)/g, the average adsorption pore diameter is 5.21nm-5.42 nm.
According to the preparation method of the fly ash-based MCM-41 mesoporous molecular sieve, the fly ash is subjected to acid washing, so that the influence of other components on the preparation of the mesoporous molecular sieve is reduced to a certain extent, the silica-alumina ratio can be improved, and the reaction activity of the mesoporous molecular sieve can be improved. And the alkali-soluble desiliconization is adopted to replace the alkali-soluble desiliconization, so that the preparation energy consumption is reduced, and the desiliconization rate of the fly ash is improved. The simple hydrothermal method adopted by the preparation has the advantages of simple process, high system integration level, easiness in industrialization and the like.
In a second aspect, the present application provides a fly ash-based MCM-41 mesoporous molecular sieve prepared by the preparation method provided herein.
The coal ash-based MCM-41 mesoporous molecular sieve provided by the application has a large specific surface area, a large pore volume and a narrow pore size distribution, has a hexagonal mesoporous structure, and can be effectively applied to the field of wastewater treatment.
The present application will be specifically described below with reference to examples, but the present application is not limited to the following examples.
Example 1
(1) Weighing 10.0g of fly ash, drying for 2.5h at 100 ℃, sieving with a 200-mesh sieve, adding into a 250mL three-neck flask, adding 100mL3.5mol/L hydrochloric acid aqueous solution, mixing uniformly, reacting for 2.5h at 85 ℃, filtering while hot after the reaction is finished, washing filter residue with deionized water to be neutral, and drying the filter residue overnight at 90 ℃ for 15h to obtain acid-washed fly ash;
(2) weighing 5.0g of acid-washing fly ash, adding the acid-washing fly ash into a hydrothermal kettle, adding 75mL of 2.4mol/L sodium hydroxide aqueous solution, stirring until the mixture is uniformly dispersed, placing the hydrothermal kettle into a drying oven, desiliconizing the mixture at 95 ℃ for 5.5 hours, and filtering the hot mixture to obtain desiliconized solution;
(3) weighing 0.32g of CTAB, adding the CTAB into a 250mL three-neck flask, adding 33.3mL of deionized water and 24.3mL of methanol, magnetically stirring to uniformly disperse the mixed solution, slowly dropwise adding 45mL of the desilication solution obtained in the step (2) into the mixed solution, stirring at 40 ℃ for 2.5h, adding 3mol/L of sulfuric acid aqueous solution to adjust the pH to 10, aging at 25 ℃ for 3.5h, transferring the obtained solution (wherein the molar ratio of silicon to CTAB is 1:0.0010) into a crystallization kettle with a polytetrafluoroethylene lining, placing the crystallization kettle into a constant-temperature oven, crystallizing at 100 ℃ for 48h, after the reaction is finished, naturally cooling, washing with deionized water to be neutral, drying at 95 ℃ for 7h, placing the solution into a muffle furnace, calcining at 560 ℃ at the temperature rise rate of 2 ℃/min for 6.5h, removing the CTAB, and obtaining the MCM-41 mesoporous molecular sieve;
(4) adding 2.5g of the fly ash-based MCM-41 mesoporous molecular sieve obtained in the step (3), 1.3g of APTES and 150mL of dry toluene into a 250mL round-bottom flask with a condenser, stirring, condensing and refluxing at 110 ℃ for 6h, cooling, filtering, washing filter residue by using n-hexane, and drying at 24 ℃ under reduced pressure for 8h to obtain the aminated and modified fly ash-based MCM-41 mesoporous molecular sieve (NH)2-MCM-41)；
(5) Into a 100mL round-bottom flask equipped with a condenser was charged 1.5g of NH obtained in step (4)2-MCM-41, 1.5g of polyvinylpyrrolidone PVP, 0.25g of phosphorus pentoxide and 50mL of absolute ethyl alcohol, stirring at 78 ℃, carrying out condensation reflux for 24h, then carrying out ultrasonic treatment for 20min, filtering, washing filter residue by using the absolute ethyl alcohol, and drying at 24 ℃ under reduced pressure for 8h to obtain the PVP grafted fly ash based MCM-41 mesoporous molecular sieve (PVP-MCM-41).
Example 2
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 0.48g, and the molar ratio of silicon to CTAB in the resulting solution was 1: 0.0015.
Example 3
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 0.64g, and the molar ratio of silicon to CTAB in the resulting solution was 1: 0.0020.
Example 4
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 0.80g, and the molar ratio of silicon to CTAB in the resulting solution was 1: 0.0025.
Example 5
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 0.96g, and the molar ratio of silicon to CTAB in the resulting solution was 1: 0.0030.
Example 6
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 1.12g, and the molar ratio of silicon to CTAB in the resulting solution was 1: 0.0035.
Example 7
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 1.28g, the molar ratio of silicon to CTAB in the resulting solution was 1:0.0040, the crystallization time was 37 hours and the calcination temperature was 600 ℃.
Example 8
The same procedure as in example 1 was repeated, except that CTAB was used in an amount of 1.44g, the molar ratio of silicon to CTAB in the resulting solution was 1:0.0045, the crystallization time was 40 hours and the calcination temperature was 580 ℃.
The chemical composition of the fly ash in example 1 was analyzed by an X-ray fluorescence spectrometer model S2range of brueck AXS, germany, and the results are shown in table 1.
TABLE 1 analysis results of chemical composition of fly ash
Composition of matter Content (%) Composition of matter Content (%)
SiO2 49.12 MgO 2.05
Al2O3 29.05 TiO2 3.52
Fe2O3 4.88 Na2O 0.70
CaO 6.12 P2O5 0.38
K2O 3.78 SO3 0.40
The fly ash-based MCM-41 mesoporous molecular sieve and NH in example 1 were subjected to X-ray powder diffractometer using model D/Max-2200PC from RigaKu, Japan2The diffraction patterns of the XRD powder obtained by analyzing the-MCM-41 and the PVP-MCM-41 are shown in figure 1, and the three diffraction peaks respectively have a diffraction peak near 2.0 degrees and correspond to a (100) crystal face, MCM-41 and NH2MCM-41 shows a weaker diffraction peak near 3.7 degrees and 4.3 degrees respectively, corresponding to the (110) crystal face and the (200) crystal face, and the diffraction peaks are both characteristic diffraction peaks of a hexagonal mesoporous structure. After modification, NH is caused because the modified group enters MCM-41 pore channels to reduce the order of hexagonal pore channels2The intensity of the characteristic peak of MCM-41 and PVP-MCM-41 is reduced, but the existence of the crystal face diffraction peak indicates that the two-dimensional hexagonal channel structure is still stable.
The fly ash-based MCM-41 mesoporous molecular sieve and NH in the example 1 are treated by a TENSOR27 type Fourier transform infrared spectrometer of Bruker, Germany2Infrared spectrum analysis of-MCM-41 and PVP-MCM-41, the obtained infrared spectrum is shown in figure 2, the three are 798cm-1And 1086cm-1The nearby absorption peaks are respectively attributed to the symmetric stretching vibration and the antisymmetric stretching vibration of the Si-O-Si bond, which indicates that the main structure of the material is the Si-O bond. NH (NH)2-MCM-41 at 1578cm-1The nearby absorption peak belongs to the bending vibration of an N-H bond in the amino, which indicates that the amino group is successfully grafted on the fly ash-based MCM-41 mesoporous molecular sieve. PVP-MCM-41 at 1665cm-1The nearby absorption peak belongs to the stretching vibration absorption peak of C ═ O, which indicates that carbonyl groups are successfully grafted on the fly ash-based MCM-41 mesoporous molecular sieve.
The fly ash-based MCM-41 mesoporous molecular sieve in example 1 was subjected to structural analysis by a Hitachi SU8100 scanning electron microscope SEM manufactured by Hitachi, Ltd., and the structure thereof was found to be in a rod-like distribution as shown in FIG. 3.
The fly ash-based MCM-41 mesoporous molecular sieve and NH in example 1 were subjected to transmission electron microscopy TEM of HT7700 type produced by Hitachi, Ltd2-MCM-41 and PVP-MCM-41 are subjected to structure analysis, and the obtained fly ash based MCM-41 mesoporous molecular sieve and NH are obtained2The TEM images of the MCM-41 and the PVP-MCM-41 are shown in figure 4, and the three have a regular two-dimensional hexagonal mesoporous structure and a regular arrangement structure in the direction parallel to the pore channel, which shows that the material has a regular two-dimensional hexagonal mesoporous structure and good spatial pore channel property.
For the fly ash-based MCM-41 mesoporous molecular sieve and NH in examples 1-82-MCM-41 and PVP-MCM-41 were subjected to BET specific surface area test, test procedure: 1g of the sample is weighed, dehydrated, dried and vacuumed at 300 ℃ for 12h, and then characterized by a rapid specific surface area and pore size analyzer, model ASAP2020HD88 from macken usa. The test results obtained are shown in table 2, and it can be seen that the material has a large specific surface area and a large pore volume. The obtained fly ash-based MCM-41 mesoporous molecular sieve and NH in the example 12The pore size distribution diagrams of-MCM-41 and PVP-MCM-41 are shown in figure 5, and it can be seen that the pore size distribution trends of the three are generally consistent and the pore size distribution is narrow, which indicates that the material has a relatively uniform pore channel structure, and the modified fly ash-based MCM-41 mesoporous molecular sieve does not have a serious pore channel blockage phenomenon. Nitrogen adsorption-desorption and the like of the obtained fly ash-based MCM-41 mesoporous molecular sieve in example 1The temperature diagram is shown in fig. 6, and it can be seen that the nitrogen adsorption-desorption isotherm belongs to type IV in the IUPAC classification standard and is accompanied by a hysteresis loop of type H1, which indicates that the material has a relatively uniform pore structure, and the hysteresis loop occurs due to the capillary condensation phenomenon generated during adsorption.
TABLE 2 BET specific surface area test results
Figure BDA0003177585160000071
Figure BDA0003177585160000081
For the fly ash-based MCM-41 mesoporous molecular sieve and NH in example 12-MCM-41 and PVP-MCM-41 lead ion adsorption performance is analyzed, and the analysis process is as follows:
process 1: weighing 1.60g of lead nitrate (analytically pure) and adding the lead nitrate into a 100mL beaker, adding deionized water, stirring until the lead nitrate is completely dissolved, transferring the solution into a 1000mL volumetric flask, adding deionized water to dilute the solution to a scale, and obtaining stock solution with lead ion concentration of 1000 mg/L;
and (2) a process: adding 100mL of stock solution in the process 1 into a 250mL conical flask, dropwise adding 0.1mol/L nitric acid aqueous solution to adjust the pH value to 5, adding 0.25g of the fly ash-based MCM-41 mesoporous molecular sieve in the example 1, placing the conical flask into a constant-temperature oscillator, adsorbing at 25 ℃ for 240min at the rotating speed of 150r/min, filtering the adsorption solution by using a 0.22 mu m filter membrane, and finally measuring the content of lead ions in the filtrate by using an ultraviolet-visible spectrophotometer;
and 3, process: except that fly ash based MCM-41 mesoporous molecular sieve is replaced by NH2-MCM-41, otherwise identical to process 2;
and 4, process: the process 2 is the same except that the fly ash-based MCM-41 mesoporous molecular sieve is replaced by PVP-MCM-41. The obtained fly ash-based MCM-41 mesoporous molecular sieve and NH2The adsorption effects of-MCM-41 and PVP-MCM-41 are shown in FIG. 7, the TEM image of PVP-MCM-41 adsorbing lead ions is shown in FIG. 8, and it can be seen from FIG. 7 that adsorption before and after modificationThe adsorbent has good adsorption performance on lead ions, and the adsorption performance is obviously improved after modification, which is probably because the adsorption sites on the surface of the adsorbent are increased after amino functional modification and PVP functional modification.
In summary, the fly ash-based MCM-41 mesoporous molecular sieve provided by the application has the advantages of large specific surface area, large pore volume, narrow pore size distribution, hexagonal mesoporous structure, good adsorption performance on lead ions, and effective application in the field of wastewater treatment.

Claims (10)

1. A preparation method of a fly ash-based MCM-41 mesoporous molecular sieve is characterized by comprising the following steps:
(1) adding the fly ash into a hydrochloric acid aqueous solution, reacting for 2-4 h at 80-90 ℃, and filtering to obtain acid-washed fly ash;
(2) adding a sodium hydroxide aqueous solution into the acid-washed fly ash, desiliconizing for 5-6 h at the temperature of 90-100 ℃, and filtering to obtain a desiliconized solution;
(3) adding deionized water and methanol into Cetyl Trimethyl Ammonium Bromide (CTAB), dropwise adding the desiliconization solution, mixing for 2-3 h at 35-45 ℃, adjusting the pH to 9-11, aging the obtained solution for 3-4 h, crystallizing and calcining to obtain the fly ash-based MCM-41 mesoporous molecular sieve, wherein the molar ratio of silicon to CTAB in the obtained solution is 1 (0.0010-0.0045).
2. The preparation method of claim 1, wherein the concentration of the hydrochloric acid aqueous solution is 3-4 mol/L, and the volume ratio of the mass of the fly ash to the hydrochloric acid aqueous solution is 1 (9-11) g/mL;
the concentration of the sodium hydroxide aqueous solution is 2-2.5 mol/L, and the volume ratio of the mass of the acid-washing fly ash to the sodium hydroxide aqueous solution is 1 (14-16) g/mL.
3. The method of claim 1, wherein the volume ratio of the desiliconized solution, the methanol and the deionized water is 1 (0.43-0.66) to (0.6-0.8).
4. The preparation method according to claim 1, wherein the crystallization temperature is 95-105 ℃, and the crystallization time is 36-48 h; the calcining temperature is 550-600 ℃, the heating rate of the calcining is 1-3 ℃/min, and the calcining time is 6-7 h.
5. The preparation method according to claim 1, wherein the specific surface area of the fly ash-based MCM-41 mesoporous molecular sieve is 910m2/g-950m2Per g, pore volume of 0.70cm3/g-0.90cm3(ii)/g, the average adsorption pore diameter is 5.58nm-5.80 nm.
6. The method of claim 1, further comprising the steps of:
mass is taken as M1The fly ash-based MCM-41 mesoporous molecular sieve is added with M by mass23-aminopropyltriethoxysilane APTES and volume V1Stirring the dry toluene, condensing and refluxing the mixture for 5 to 7 hours at the temperature of between 105 and 115 ℃, and filtering the mixture to obtain the aminated and modified fly ash-based MCM-41 mesoporous molecular sieve, wherein M is1:M2:V1Is 1 (0.4-0.6) to 50-70 g/g/mL.
7. The preparation method according to claim 6, wherein the specific surface area of the amination-modified fly ash-based MCM-41 mesoporous molecular sieve is 710m2/g-750m2Per g, pore volume of 0.56cm3/g-0.81cm3(ii)/g, the average adsorption pore diameter is 5.24nm-5.45 nm.
8. The method of claim 6, further comprising the steps of:
mass is taken as M3The amination modified fly ash-based MCM-41 mesoporous molecular sieve is added with M by mass4Polyvinylpyrrolidone PVP with mass M5Phosphorus pentoxide and volume V2Stirring the absolute ethyl alcohol at the temperature of between 75 and 80 ℃, condensing and refluxing for 20 to 28 hours, carrying out ultrasonic treatment for 15 to 25 minutes, and filtering to obtain the productPVP grafted fly ash based MCM-41 mesoporous molecular sieve, wherein, M3:M4:M5:V21:1 (0.14-0.19) g/g/g/mL (30-38).
9. The preparation method according to claim 8, wherein the PVP grafted fly ash based MCM-41 mesoporous molecular sieve has a specific surface area of 220m2/g-250m2Per g, pore volume of 0.38cm3/g-0.55cm3(ii)/g, the average adsorption pore diameter is 5.21nm-5.42 nm.
10. A fly ash-based MCM-41 mesoporous molecular sieve prepared by the preparation method of any of claims 1-9.
CN202110837237.5A 2021-07-23 2021-07-23 Preparation method of fly ash-based MCM-41 mesoporous molecular sieve and product thereof Pending CN113578260A (en)

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