CN-116688883-B - Amino modified biochar/SiO2Preparation method of composite aerogel

Abstract

The invention belongs to the field of new material preparation, and particularly relates to a preparation method of amino modified biochar/SiO 2 composite aerogel. The invention firstly takes cellulose as a template and tetraethoxysilane as a silicon source to prepare cellulose/SiO 2 composite aerogel, the composite aerogel of biochar/SiO 2 is obtained after high-temperature calcination, and then the polymer after the crosslinking reaction of 3-glycidyloxypropyl trimethoxy silane and diethylenetriamine is adopted to carry out amino modification on the composite aerogel of biochar/SiO 2 , so as to obtain the amino modified biochar/SiO 2 composite aerogel. The amino modified biochar/SiO 2 composite aerogel prepared by the method has high selectivity on CO 2 adsorption and is simple in preparation process.

Inventors

• JI BIAO
• ZHENG XUDONG
• XU ZIHUAI
• LI ZHONGYU
• RONG JIAN

Assignees

• 常州大学

Dates

Publication Date

20260508

Application Date

20230609

Claims (9)

1. 1. A preparation method of amino modified biochar/SiO 2 composite aerogel is characterized by comprising the steps of hydrolyzing cellulose to obtain cellulose nanocrystals with chiral spiral structures, reacting the cellulose nanocrystals with tetraethoxysilane to prepare cellulose/SiO 2 composite aerogel, calcining the cellulose nanocrystals at high temperature to obtain biochar/SiO 2 composite aerogel, finally performing amino modification on the biochar/SiO 2 composite aerogel by using polymers obtained after cross-linking reaction of 3-glycidoxypropyl trimethoxysilane and diethylenetriamine to obtain amino modified biochar/SiO 2 composite aerogel, mixing concentrated sulfuric acid and distilled water to prepare a concentrated sulfuric acid aqueous solution, adding absorbent cotton into the concentrated sulfuric acid aqueous solution, stirring the mixture in 45 ℃ oil bath for 3 hours, pouring the mixture into ice water, standing and precipitating for 12 hours, removing supernatant, centrifuging a suspension at the lower layer, and dialyzing and purifying the suspension until the pH is more than 2.4 to obtain the cellulose nanocrystals.
2. 2. The method for preparing the amino-modified biochar/SiO 2 composite aerogel according to claim 1, comprising the following steps: (1) Mixing cellulose nanocrystals with ethyl orthosilicate, stirring at a constant speed at room temperature, standing the solution, removing supernatant, replacing the lower layer solution with water and ethanol, and performing supercritical drying to obtain cellulose/SiO 2 composite aerogel; (2) Placing the cellulose/SiO 2 composite aerogel into a tube furnace for high-temperature calcination treatment to obtain biochar/SiO 2 composite aerogel; (3) Adding 3-glycidoxypropyl trimethoxy silane and diethylenetriamine into tetrahydrofuran, stirring for 4 hours at 70 ℃, cooling to 25 ℃, continuously stirring for 25 minutes, adding biochar/SiO 2 composite aerogel, ethanol and nitric acid, and stirring at room temperature for reaction to obtain amino modified biochar/SiO 2 composite aerogel.
3. 3. The preparation method of the amino modified biochar/SiO 2 composite aerogel according to claim 1, wherein the mass ratio of absorbent cotton to concentrated sulfuric acid aqueous solution is 1:21, and the molar ratio of concentrated sulfuric acid, distilled water and ice water is 1:3:60.
4. 4. The method for preparing amino-modified biochar/SiO 2 composite aerogel according to claim 2, wherein the volume ratio of cellulose nanocrystals to ethyl orthosilicate in step (1) is 12 (1.8-3.3).
5. 5. The method for preparing the amino-modified biochar/SiO 2 composite aerogel according to claim 2, wherein in the step (1), stirring is carried out at room temperature at a constant speed for 1h, and the solution is kept stand for 24h.
6. 6. The method for preparing the amino modified biochar/SiO 2 composite aerogel according to claim 2, wherein the specific conditions of the high-temperature calcination in the step (2) are that the calcination is carried out for 6 hours under the protection of N 2 under the condition of heating to 450 ℃.
7. 7. The method for preparing the amino modified biochar/SiO 2 composite aerogel according to claim 2, wherein the molar ratio of 3-glycidoxypropyl trimethoxysilane, diethylenetriamine and ethyl orthosilicate is (5-12): 3-4): 8-15.
8. 8. The method for preparing an amino-modified biochar/SiO 2 composite aerogel according to claim 7, wherein the molar ratio of 3-glycidoxypropyl trimethoxysilane, diethylenetriamine and ethyl orthosilicate is (10-12): 4 (8-15).
9. 9. The method for preparing amino-modified biochar/SiO 2 composite aerogel according to claim 2, wherein the stirring reaction time at room temperature in the step (3) is 1h.

Description

Preparation method of amino modified biochar/SiO 2 composite aerogel Technical Field The invention belongs to the field of new material preparation, and in particular relates to a preparation method of amino modified biochar/SiO 2 composite aerogel. Background During urban development, land utilization and migration, green vegetation on earth is cut down in large quantities, resulting in a decrease in the CO 2 purification capacity of the nature itself. Emissions from the combustion of fossil fuels have led to an increasing concentration of CO 2 in the atmosphere, and environmental problems with CO 2 have become more serious. The capture of CO 2 is therefore of great interest for solving global warming and greenhouse effect problems. The CO 2 capture, utilization and sequestration technology is one of the most direct and effective technological means considered to rapidly reduce atmospheric CO 2 concentrations. Heretofore, large scale CO 2 separation processes have been primarily liquid amine absorption technologies. The use of monoethanolamine, diethanolamine and methyldiethanolamine in aqueous solution is used for large scale capture of CO 2. Although the absorption process has proven effective in capturing CO 2, significant drawbacks remain. The main problems are the corrosiveness of the liquid amine, the tendency to amine losses during operation, and the energy consumption during regeneration. Aiming at the current situation, most institutions abroad develop other adsorbents, and find that the solid adsorbent has better adsorption effect. These limitations are overcome by attaching amine functional groups to the high surface area solids. The aerogel has wide development prospect due to the excellent properties of low density, high porosity, high specific surface area, low heat conductivity coefficient, low dielectric constant and the like and the unique structure. The traditional silicon aerogel has poor mechanical properties and is fragile, and the cellulose aerogel not only has the excellent properties of the traditional aerogel and the polymer aerogel, but also has excellent biocompatibility and degradability, and can be used as an excellent supporting material for enhancing the silicon aerogel. Disclosure of Invention The invention provides a preparation method of amino modified biochar/SiO 2 composite aerogel, which can be used for adsorbing CO 2 from air and has higher adsorptivity and selectivity to CO 2. The technical scheme adopted by the invention is as follows: A preparation method of amino modified biochar/SiO 2 composite aerogel comprises the steps of hydrolyzing cellulose to obtain cellulose nanocrystals with chiral spiral structures, reacting the cellulose nanocrystals with tetraethoxysilane to prepare cellulose/SiO 2 composite aerogel, calcining the cellulose nanocrystals at high temperature to obtain biochar/SiO 2 composite aerogel, and finally amino modifying the biochar/SiO 2 composite aerogel by using a polymer obtained by crosslinking reaction of 3-glycidoxypropyl trimethoxysilane and diethylenetriamine to obtain the amino modified biochar/SiO 2 composite aerogel. The method specifically comprises the following steps: (1) Mixing concentrated sulfuric acid with distilled water to prepare concentrated sulfuric acid aqueous solution, putting absorbent cotton into the concentrated sulfuric acid aqueous solution, stirring for 3 hours in an oil bath at 45 ℃, pouring into ice water, standing and precipitating for 12 hours, removing supernatant, centrifuging the lower suspension, and dialyzing and purifying to pH >2.4 to obtain Cellulose Nanocrystals (CNCs) with chiral spiral structures; (2) Mixing CNCs with chiral spiral structure with Tetraethoxysilane (TEOS), stirring at room temperature at constant speed, standing the solution, removing supernatant, replacing the lower layer solution with water and ethanol, and performing supercritical drying to obtain cellulose/SiO 2 composite aerogel; (3) Placing the cellulose/SiO 2 composite aerogel into a tube furnace for high-temperature calcination treatment to obtain biochar/SiO 2 composite aerogel; (4) Adding 3-glycidoxypropyl trimethoxy silane (GPTMS) and Diethylenetriamine (DETA) into tetrahydrofuran, stirring for 4 hours at 70 ℃, cooling to 25 ℃, continuously stirring for 25 minutes, reacting an epoxy group of the GPTMS with an amino group of the DETA to form a highly crossed compound network, adding biochar/SiO 2 composite aerogel, ethanol and nitric acid, stirring at room temperature, reacting, and carrying out condensation reaction on SiO 2 and GPTMS to enable the amino group to be grafted onto the composite aerogel, thus obtaining the amino modified biochar/SiO 2 composite aerogel. Preferably, the mass ratio of the absorbent cotton to the concentrated sulfuric acid aqueous solution in the step (1) is 1:21, and the molar ratio of the concentrated sulfuric acid, the distilled water and the ice water is 1:3:60. Preferably, the volume ratio o