Preparation Of Mesoporous Materials With Larger Pore Sizes For CO₂Adsorption And Mesoporous G-C₃N₄Photocatalyst

Ordered mesoporous materials have broad application prospect in treatment of environment pollution. This thesis focuses on the applications of ordered mesoporous materials in CO2adsorption and photo-degradation of water pollutant. Firstly, SBA-15-like mesoporous silica materials with different pore sizes were synthesized, and their CO2adsorption abilities were investigated after loading of organic amine; Secondly, using mesoporous silicas as templates, mesoporous graphite C3N4materials, a new kind of photocatalysis, were synthesized, and their photo-degradation abilities were also studied. The main progresses of this thesis are:1) The introduction of swelling agents, such as isooctane, can effectively enlarge the pore diameter and volume of SBA-15. When modified with tetraethylenepentamine (TEPA), all of these mesoporous materials exhibited excellent adsorption capacities for CO2, and can be further converted into the shaped CO2adsorbents by in-situ synthesis of mesoporous silica on the surfaces of degreasing cotton. The relationship between the pore diameters of SBA-15-like materials and CO2adsorption abilities was systematically investigated, and the results showed that the adsorption capacity of CO2was independent of the pore structure, if the template was removed before modification with TEPA. While their adsorption capacity increased with the pore diameter when the as-synthesized mesoporous materials were modified with TEPA. Thus, it is an effective route to enhance their CO2adsorption abilities by swelling pore size of as-synthesised SBA-15-like materials. The effects of pressure and temperature on CO2adsorption abilities were also studied. It was found that the composite materials exhibited different adsorption behaviors with pressure variation if the adsorption of CO2was pursued at different temperature. When adsorbed at75℃, these composites showed notable difference of CO2adsorption capacities with pressure, and the adsorption and separation of CO2on these TEPA modified mesoporous materials can be easily realized via pressure swing adsorption. Thus, these composites might play an important role in controlling the emissions of CO2.2) Mesoporous g-C3N4, a new kind of photocatalyst, can be prepared by using mesoporous silicas as hard templates.3D-SBA-15, which was prepared by adjusting pH to alter micelle size, is a suitable hard template for synthesis ordered g-C3N4materials with high surface area. Compared with the g-C3N4fabricated by direct thermal-decomposition, these mesoporous g-C3N4exhibited better abilities in photo-degradation of methyl orange dye (MO).