The Synthesis Of Ordered Mesoporous Carbon Materials And Their Performance For Carbon Dioxide Capture

In the era of"carbon peak,carbon neutrality",it is of great significance to develop an efficient,economical,green,and safe carbon dioxide（CO₂）capture and storage technology.Gas hydrate technology is one of the available technologies.One volume of hydrate can store about 164 gas volumes.The compact storage mode makes it useful as a gas storage and transportation medium.In addition,the pore structure characteristics of the mesoporous material are favorable for the contact between gas molecules and water molecules,which can achieve the purpose of forming a large number of gas hydrates in the pores of the mesoporous material without high energy-consuming stirring.The technology has the advantages of green,safe,high capture capacity,and simple regeneration,and has broad application prospects.However,the current research on the use of this technology to capture CO₂ is relatively scarce,and it is necessary to enrich the research in related fields.Therefore,in this thesis,the following studies are carried out on the synthesis of ordered mesoporous carbon materials and their CO₂ capture performance:First,ordered mesoporous carbon-silicon composites were synthesized by adjusting the synthesis steps of SBA-15,using the unremoved template（Pluronic P123）as the carbon source and sulfuric acid as the cross-linking polymerization catalyst of P123.The ordered mesoporous structure of carbon-silicon composites was characterized by 77 K nitrogen adsorption and desorption isotherms,XRD,and TEM.The pore walls were covered by carbon films,and the surface properties changed from polar to non-polar.Compared with SBA-15 material,the adsorption capacity of dry ordered mesoporous carbon-silicon composite for CO₂ increases from 4.5 mmol/g of SBA-15 to 8.8 mmol/g at 275 K and 3.0MPa.The ordered mesoporous carbon-silicon composite（R_w=3.0）with pre-adsorbed water has exhibited a CO₂ capture capacity of up to 30.0 mmol/g.Secondly,CMK-3 is synthesized by filling enough carbon source in the pores of SBA-15 by carbonization,and P123 after cross-linking polymerization can also be used as a carbon source.Therefore,ordered mesoporous carbon can be synthesized by omitting the washing and calcination steps,using P123 and sucrose as carbon sources,cross-linking polymerization in sulfuric acid solution,and carbonization.The synthesized mesoporous carbons were characterized by 77 K nitrogen adsorption and desorption isotherms,XRD,and TEM.Ordered mesoporous carbon was synthesized under the conditions of 1.5 g sulfuric acid/g（silica/P123）and 0.8 g sucrose/g（silica/P123）with a specific surface area of 1200m²/g and a pore volume of 1.35 cm³/g,the maximum pore size distribution is 3.6 nm.Under275 K and 3.4 MPa,the CO₂ adsorption capacity of the dry-ordered mesoporous carbon material was 25.0 mmol/g.The ordered mesoporous carbon material with pre-adsorbed water（R_w=2.2）has an enhanced CO₂ capture capacity of 45.9 mmol/g.Finally,in order to further improve the CO₂ capture performance of ordered mesoporous carbon materials,an ordered mesoporous carbon tube material CMK-5 with higher CO₂capture performance was synthesized.The synthesized CMK-5 materials were characterized by 77 K nitrogen adsorption and desorption isotherms,XRD,and TEM.When the mass ratio of furfuryl alcohol/SBA-15 was 0.75 g/g,the synthesized CMK-5-0.75 has a specific surface area of 1475 m²/g and a pore volume of 1.93 cm³/g,which has a double mesoporous structure with pore diameters of 4.2 nm and 2.8 nm.Under 275 K and 3.1 MPa,the CO₂ adsorption capacity of dry CMK-5-0.75 material has reached 30.0 mmol/g,and the pre-adsorbed water CMK-5-0.75 material（R_w=4.0）,the capture capacity of CO₂was as high as 58.4 mmol/g.