CN-121990581-A - Hollow Silicalite-1 zeolite with controllable mesopores, and preparation method and application thereof

CN121990581ACN 121990581 ACN121990581 ACN 121990581ACN-121990581-A

Abstract

The invention discloses a hollow Silicalite-1 zeolite with controllable mesopores, a preparation method and application thereof, and the Silicalite-1 zeolite is obtained and consists of a mesoporous shell with adjustable pore diameter and a hollow inner cavity. The Silicalite-1 zeolite is provided with a hollow cavity, provides sufficient space for amine load, has a mesoporous structure with an adjustable pore diameter within the range of 2-20 nm, and combines the amine molecular dispersion and CO 2 diffusion efficiency. The invention also provides a solid amine CO 2 adsorbent, which synchronously realizes high-capacity loading of amine, good dispersibility and efficient diffusion of CO 2 through the composite structure of the hollow cavity and the controllable mesoporous shell layer of the zeolite carrier, and breaks through the trade-off limitation of the traditional carrier between mass transfer and loading. The adsorbent can be used for medium-low temperature flue gas CO 2 concentration. The invention solves the problems of poor amine dispersibility, large CO 2 diffusion resistance, low adsorption capacity, easy inactivation and the like caused by narrow pore canal of the zeolite carrier of the existing solid amine adsorbent.

Inventors

LIU TAO
ZHAO XIAO
YANG QIAN
LIAO QINGYUN
LI CHENG
WANG JI
GAO RONGZHAO
XIE HEPING

Assignees

天府永兴实验室

Dates

Publication Date: 20260508
Application Date: 20260211

Claims (10)

1. The preparation method of the hollow Silicalite-1 zeolite with controllable mesopores is characterized by comprising the following steps: (1) Preparation of solid S-1 The solid S-1 is synthesized by adopting a hydrothermal method, firstly, an organic alkali solution and ethyl orthosilicate are added into a reaction vessel, after hydrolysis for 2-3 hours at 25-35 ℃, deionized water is added for continuous stirring for 1-2 hours, wherein the molar ratio of the ethyl orthosilicate to the organic alkali to the total water is 1 (0.17-0.27): 37, then the temperature is raised to 60-80 ℃, ethanol generated by hydrolysis of the ethyl orthosilicate is removed, water is supplemented to the original volume, the mixture is put into a crystallization kettle with a polytetrafluoroethylene lining, after crystallization for 24-72 hours at 150-170 ℃, centrifugal separation is carried out, deionized water is used for washing to be neutral, and drying is carried out for 12-24 hours at 100-120 ℃, and finally, the mixture is baked for 4-6 hours at 500-600 ℃ to obtain solid S-1 powder; (2) Preparation of hollow S-1 Adding solid S-1 powder into 0.1-1 mol/L organic alkali solution, wherein the dosage of the organic alkali solution is 5-15 mL per gram of solid S-1, stirring uniformly, then placing into a crystallization kettle with a polytetrafluoroethylene lining, stirring for 24-72 h at 150-170 ℃, centrifugally separating, washing to be neutral by deionized water, drying for 12-24 h at 100-120 ℃, and then roasting for 4-6 h at 500-600 ℃ to obtain hollow S-1; (3) Preparation of hollow mesoporous S-1 The method for treating the hollow S-1 by using the mixed alkali solution of the organic alkali and the inorganic alkali comprises the steps of adding the hollow S-1 into the mixed alkali solution of 0.1-0.5 mol/L, stirring and heating to 40-60 o ℃ for 4-6 hours, keeping the temperature of the mixed alkali solution at 5-15 mL per gram of the hollow S-1, controlling the molar ratio of the molar amount of the organic alkali to the total molar amount of the organic alkali and the inorganic alkali in the mixed alkali solution to be (0-1): 1, namely the molar amount of the organic alkali to the total molar amount of the organic alkali to be (0-1): 1, centrifugally separating, washing to be neutral by deionized water, drying at 100-120 ℃ for 12-24 hours, roasting at 500-600 ℃ for 4-6 hours, and obtaining the hollow mesoporous S-1, and realizing that the mesoporous size is adjustable within the range of 2-20 nm by controlling the concentration and the dosage of the mixed alkali.
2. The method of claim 1, wherein in the steps (1) - (3), the organic base is at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and tetrapropylammonium bromide, and the inorganic base is at least one of sodium hydroxide and potassium hydroxide.
3. The hollow Silicalite-1 zeolite with controllable mesopores prepared by the method of claim 1 or 2, which consists of a mesoporous shell with adjustable pore diameter and a hollow internal cavity.
4. The hollow Silicalite-1 zeolite with controllable mesopores as claimed in claim 3, wherein the shell layer has mesopores with an adjustable pore diameter in the range of 2-20 nm.
5. Use of the hollow Silicalite-1 zeolite with controllable mesopores according to claim 3 or 4 for medium and low temperature flue gas CO 2 capture.
6. The process according to claim 5, wherein the solid amine adsorbent is a carrier for CO 2 .
7. A solid amine CO 2 adsorbent based on a hollow Silicalite-1 zeolite having controlled mesopores according to claim 3 or 4, which is obtained by impregnating an organic amine on a support with a hollow Silicalite-1 zeolite having controlled mesopores as support.
8. The solid amine CO 2 adsorbent of hollow Silicalite-1 zeolite having controlled mesopores according to claim 7, wherein the method of impregnating the organic amine is as follows: Degassing the hollow Silicalite-1 zeolite with controllable mesopores for 2 hours under the vacuum condition of 110 ℃, then adding the hollow Silicalite-1 zeolite into a methanol solution containing organic amine, controlling the loading amount of the organic amine to be 30% -40% of the mass of the adsorbent, stirring at room temperature until the methanol is almost completely volatilized, and drying to obtain the CO 2 adsorbent.
9. The solid amine CO 2 adsorbent with a controllable mesoporous hollow Silicalite-1 zeolite according to claim 8, wherein the organic amine is polyethylenimine and has a molecular weight of 300-1800 g/mol.
10. Use of a CO 2 adsorbent based on a hollow Silicalite-1 zeolite with controlled mesopores according to claim 7 in carbon sequestration.

Description

Hollow Silicalite-1 zeolite with controllable mesopores, and preparation method and application thereof Technical Field The invention belongs to the technical field of carbon trapping materials, and particularly relates to a Silicalite-1 zeolite carrier for adsorbing solid amino CO 2, a preparation method and application thereof. Background CO 2 capture and sequestration (CCS) technology has become one of the key paths to deal with climate change. Among the numerous CO 2 capture schemes, solid amine-based adsorbents are considered to be a potential new generation of capture materials due to their advantages of high adsorption capacity, low corrosiveness, relatively controllable regeneration energy consumption, and the like. The materials are usually constructed by loading organic amine (such as polyethyleneimine, PEI) on a porous carrier, and the performance of the materials is greatly dependent on the pore structure, the surface property and the mass transfer efficiency of the carrier. The porous carriers commonly used at present include silica, activated carbon, alumina, zeolite and the like. Among them, silicalite-1 (S-1) zeolite is widely used as an amine-supported carrier due to its regular MFI topology, high specific surface area and good thermal stability. However, the conventional S-1 zeolite is mainly composed of micropores (aperture is less than 2 nm), and narrow and tortuous pore channels cause the outstanding problems that (1) amine loading is limited, micropore volume is limited, high-capacity amine loading is difficult to realize, (2) amine dispersibility is poor, amine molecules are easy to agglomerate at the pore openings, effective active sites are reduced, (3) diffusion resistance is large, mass transfer of CO 2 in the micropores is slow, adsorption kinetics is slow, and (4) blocking and deactivation are easy, and degradation or blocking of pore channels of the amine can occur in a regeneration process, so that the circulation stability is influenced. In recent years, hollow mesoporous materials have shown superiority in the fields of catalysis, energy storage, drug delivery and the like due to high specific surface area, large pore volume, adjustable pore size distribution and good mass transfer performance. If the hollow structure and the controllable mesoporous can be introduced into Silicalite-1 zeolite, the amine load space, the dispersibility and the CO 2 diffusion efficiency of the zeolite can be expected to be synchronously improved. However, the existing cavitation and pore-expanding methods in zeolite are mostly designed for an acidic zeolite system, and are often dependent on or limited by acidic components of zeolite in the treatment process, so that the pore size distribution is wide, the regulation and control precision is insufficient, and a refined mesoporous structure matched with the molecular size of amine (usually in the range of a few nanometers) and the diffusion path of CO 2 is difficult to realize. Therefore, the development of the pure silicalite carrier which has a hollow cavity, controllable mesoporous shell layers and no acid interference has important significance for promoting the development of the solid amine adsorbent to the high-efficiency, stable and practical directions. Disclosure of Invention Aiming at the defects and the blank in the prior art, the invention provides a hollow Silicalite-1 zeolite with controllable mesopores, a preparation method and application thereof, so as to obtain a pure Silicalite carrier which has a refined mesopore structure with a hollow cavity, a controllable mesopore shell layer, an amine molecular size matched with a CO 2 diffusion path and no acid interference, and solves the problems of poor amine dispersibility, high CO 2 diffusion resistance, low adsorption capacity, easy inactivation and the like caused by the narrow pore channel of the conventional solid amine adsorbent zeolite carrier. Aiming at the comprehensive requirements of the solid amine adsorbent on the aspects of pore structure, surface chemical property and diffusion mass transfer efficiency of the carrier, the invention provides a pure silicalite material which is free of acidity and has adjustable mesoporous shell layers and hollow cavities, and aims to break through the limitations of the traditional microporous zeolite on the aspects of amine loading capacity, CO 2 adsorption kinetics and cycle stability. The invention provides a hollow Silicalite-1 (abbreviated as S-1) zeolite with controllable mesopores and a preparation method thereof, comprising the following steps: (1) Preparation of solid S-1 The solid S-1 is synthesized by adopting a hydrothermal method, firstly, an organic alkali solution and ethyl orthosilicate are added into a reaction vessel, after hydrolysis for 2-3 hours at 25-35 ℃, deionized water is added for continuous stirring for 1-2 hours, wherein the molar ratio of the ethyl orthosilicate to the organic alkali to the total water is