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CN-121988280-A - Fly ash-based hierarchical porous molecular sieve composite material and preparation method and application thereof

CN121988280ACN 121988280 ACN121988280 ACN 121988280ACN-121988280-A

Abstract

The invention relates to a fly ash-based hierarchical porous molecular sieve composite material, and a preparation method and application thereof, and belongs to the technical field of molecular sieve composite materials. The invention provides a preparation method of a fly ash-based hierarchical porous molecular sieve composite material, which aims to solve the problems that the existing fly ash-based molecular sieve has a single pore structure, can only adsorb single pollutant and is complex in preparation process. According to the invention, the microporous-mesoporous-macroporous tertiary pore canal is constructed, the mass transfer efficiency and the adsorption activity are improved, double active sites are formed through metal modification, heavy metals and CO 2 can be synchronously adsorbed, and the capacity of CO 2 is improved by 10-15% by heavy metal loading. The invention adopts a one-step method for preparation, has simplified process, low cost and high fly ash consumption, and has the benefits of solid waste recycling and multi-pollutant cooperative treatment.

Inventors

  • LU SHUANG
  • WU XIAOGANG
  • Shang Guoyong
  • HUANG JIAWEI
  • HE SHENGJUN
  • WANG CHAO
  • ZHANG DANDAN
  • ZHANG BIN
  • DIAO JUN
  • JI QINGTAO
  • LI LI

Assignees

  • 哈密绿建环保科技材料有限责任公司
  • 哈尔滨工业大学

Dates

Publication Date
20260508
Application Date
20260325

Claims (10)

  1. 1. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material is characterized by comprising the following steps of: Step one, performing mechanical-chemical coupling activation on fly ash with the particle size less than or equal to 50 mu m, activating by adopting sulfuric acid solution, and drying until the water content is less than or equal to 5%, so as to obtain activated fly ash; Mixing the obtained activated fly ash with sodium hydroxide, performing alkali fusion activation for 2-4 hours at 600-800 ℃, and cooling and crushing to be less than or equal to 100 mu m to obtain alkali fusion fly ash powder; Adding a mesoporous template agent and a macroporous pore-forming agent into the obtained alkali-fused fly ash powder, adding deionized water, stirring to form a gelatinous precursor, and performing hydrothermal crystallization at 120-180 ℃ for 24-72 h to obtain a crystallized product; Washing the obtained crystallized product until the pH value of the washing liquid is 6-7, drying, roasting at 480-520 ℃, and removing the template agent to obtain the multistage hole ZSM-5 molecular sieve; And fifthly, carrying out ion exchange impregnation on the obtained hierarchical pore ZSM-5 molecular sieve by adopting copper nitrate or zinc nitrate solution, and drying and roasting after solid-liquid separation to obtain the metal modified hierarchical pore molecular sieve composite material.
  2. 2. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material is characterized in that in the first step, mechanical activation adopts double planetary grinding, the rotating speed is 2000-3000 r/min, the grinding time is 1-2 h, and the concentration of sulfuric acid solution used for chemical activation is 0.3-0.7 mol/L.
  3. 3. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material according to claim 1 or 2, wherein the mass ratio of activated fly ash to sodium hydroxide in the second step is 6:2-3, the alkali fusion activation temperature is 700 ℃, and the alkali fusion activation time is 3 hours.
  4. 4. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material is characterized in that in the third step, the mesoporous template agent is P123, the addition amount of the P123 is 6-10% of the mass of alkali-fused fly ash powder, the macroporous pore-forming agent is PMMA microspheres, and the addition amount of the PMMA microspheres is 3-7% of the mass of alkali-fused fly ash powder.
  5. 5. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material is characterized in that in the third step, the liquid-solid ratio of deionized water to alkali-melted fly ash powder is 2-5 mL/g, the stirring speed is 300-500 r/min, the stirring time is 30-60 min, the hydrothermal crystallization temperature is 150 ℃, and the hydrothermal crystallization time is 48h.
  6. 6. The preparation method of the fly ash-based hierarchical porous molecular sieve composite material is characterized in that in the fourth step, the drying temperature is 100-110 ℃, the drying time is 10-14 h, the roasting heating rate is 3-7 ℃ per minute, and the roasting time is 3-5 h.
  7. 7. The preparation method of the fly ash-based hierarchical pore molecular sieve composite material is characterized in that in the fifth step, the concentration of a copper nitrate or zinc nitrate solution is 0.05-0.15 mol/L, the solid-to-liquid ratio of a hierarchical pore ZSM-5 molecular sieve to the copper nitrate or zinc nitrate solution is 1:40-60 g/mL, the impregnation temperature is 55-65 ℃, the impregnation time is 4-8 h, the drying temperature after impregnation is 100-110 ℃, the drying time is 10-14 h, the roasting temperature is 480-520 ℃ and the roasting time is 2-4 h.
  8. 8. The fly ash-based hierarchical porous molecular sieve composite material prepared by the preparation method according to any one of claims 1 to 7, which is characterized by having a microporous-mesoporous-macroporous three-stage pore structure, wherein the specific surface area is not less than 550m 2 /g, the total pore volume is not less than 0.8cm 3 /g, the adsorption rate to Pb 2+ is not less than 97%, and the adsorption capacity to CO 2 is not less than 2.5mmol/g.
  9. 9. Use of the fly ash-based hierarchical porous molecular sieve composite material according to claim 8 in deep treatment of heavy metal wastewater and/or in carbon dioxide capture of industrial flue gas.
  10. 10. The application of the composite material according to claim 9, wherein when the composite material is used for heavy metal wastewater treatment and CO 2 trapping, the pH value of the wastewater containing Pb 2+ 、Cd 2+ is adjusted to 5-7, the composite material is added according to the adding amount of 0.5-2 g/L, the composite material is stirred and adsorbed for 60-120 min at 25-35 ℃, the composite material is directly filled in a fixed bed adsorption column, and the CO 2 -containing mixed gas is introduced at the gas space velocity of 500-1000 h -1 under the conditions of the adsorption temperature of 25-60 ℃ and the pressure of 0.1-0.3 MPa, so that CO 2 trapping is realized.

Description

Fly ash-based hierarchical porous molecular sieve composite material and preparation method and application thereof Technical Field The invention belongs to the technical field of molecular sieve composite materials, and particularly relates to a fly ash-based hierarchical porous molecular sieve composite material, and a preparation method and application thereof. Background Along with the continuous promotion of industrial scale, the fly ash is used as a large amount of industrial solid waste generated by a coal-fired power plant, the annual discharge amount is considerable, and the conventional stockpiling treatment mode has a plurality of defects that not only occupies a large amount of land resources, but also multiple environmental pollution of atmosphere, soil and water is easily caused by the ways of dust diffusion, percolate leakage and the like, so that harmless and recycling treatment of solid waste is urgent. From the aspect of component characteristics, the fly ash is rich in silicon and aluminum core elements, wherein the content of silicon dioxide reaches 50-60%, and the content of aluminum oxide reaches 20-30%, so that the fly ash is a high-quality natural silicon-aluminum raw material for synthesizing high-performance functional materials such as molecular sieves, and the like, thereby developing resource utilization and conforming to the green development concept of solid waste resource utilization. However, the existing fly ash-based molecular sieve and pollutant adsorption technology still has a plurality of core short plates which are disjointed with the main flow technical path of fly ash recycling, so that the industrial application of the fly ash-based molecular sieve and pollutant adsorption technology is difficult to fall to the ground. Most of traditional products are single microporous structures with the pore diameters smaller than 2nm, and the narrow pore channels lead to large pollutant diffusion resistance and low mass transfer efficiency, so that the traditional products cannot adapt to macromolecule pollutants or multi-pollutant cooperative adsorption scenes, and the potential advantages of the coal ash classification treatment are not exerted. Meanwhile, most of the prior art only aims at single pollutant adsorption, cannot meet the requirement of industrial wastewater and flue gas multi-pollutant cooperative treatment, does not construct double active sites through metal modification, and is difficult to synchronously and efficiently adsorb heavy metals and CO 2. In addition, the existing hierarchical porous molecular sieve is prepared by a multi-step template method, the process is complicated, the template agent cost is high, low-cost large-scale production cannot be realized, part of the technology only uses the fly ash as a silicon-aluminum source directly, the dissolution rate of silicon-aluminum components is low, the purity and adsorption activity of the molecular sieve are insufficient, and the utilization of solid waste is insufficient. In summary, the prior art has obvious blank, and a solution scheme for adapting to the multi-pollutant cooperative treatment is needed to meet the requirements of high-efficiency recycling of the fly ash and comprehensive treatment of industrial pollution. Disclosure of Invention The invention provides a fly ash-based hierarchical porous molecular sieve composite material, a preparation method and application thereof, and aims to solve the problems that the existing fly ash-based molecular sieve has a single pore structure, can only adsorb single pollutant and is complex in preparation process. The technical scheme of the invention is as follows: a preparation method of a fly ash-based hierarchical porous molecular sieve composite material comprises the following steps: Step one, performing mechanical-chemical coupling activation on fly ash with the particle size less than or equal to 50 mu m, activating by adopting sulfuric acid solution, and drying until the water content is less than or equal to 5%, so as to obtain activated fly ash; Mixing the obtained activated fly ash with sodium hydroxide, performing alkali fusion activation for 2-4 hours at 600-800 ℃, and cooling and crushing to be less than or equal to 100 mu m to obtain alkali fusion fly ash powder; Adding a mesoporous template agent and a macroporous pore-forming agent into the obtained alkali-fused fly ash powder, adding deionized water, stirring to form a gelatinous precursor, and performing hydrothermal crystallization at 120-180 ℃ for 24-72 h to obtain a crystallized product; Washing the obtained crystallized product until the pH value of the washing liquid is 6-7, drying, roasting at 480-520 ℃, and removing the template agent to obtain the multistage hole ZSM-5 molecular sieve; And fifthly, carrying out ion exchange impregnation on the obtained hierarchical pore ZSM-5 molecular sieve by adopting copper nitrate or zinc nitrate solution, and drying and roasting after