Synthesis Of Amino Functionalized Mesoporous Molecular Silia KIT-6 And Its Adsorption On Carbon Dioxide

With the rapid development of the industrialization level,burning of fossil fuels results in a sharp increase on the concentration of carbon dioxide in the global atmosphere,causing serious harm to the environment since the industrial revolution.In recent years,owing to the long-term global warming and strong EI Nino events,land surface,ocean temperature,sea level and greenhouse gas emissions have reached a new historical height.Therefore,how to capture and store a large amount of carbon dioxide in the environment has become a hot spot.Among them,adsorption method was widely used by its low energy-consumption,low corrosion and simplicity of operator.In this paper,mesoporous silica KIT-6 was prepared and modified by amine,and the adsorption capacity of carbon dioxide was studied.In this paper,KIT-6 was synthesized by using nonionic three block copolymer P123 as the structure directing agent and tetraethyl orthosilicate?TEOS?as the silica source.The PE-KIT-6 was prepared by adding a certain amount of 1,3,5-three toluene as the pore expanding agent.The physical properties were obtained by N₂ desorption test.The specific surface area was 646.57 m².g^-1 and 207.61 m².g^-1,respectively,and the pore capacities were 1.4015 cm³.g^-1 and 0.7224 cm³.g^-1.The pore sizes were 4.61nm and 6.06 nm,respectively.TETA and TEPA and 3N with the mass percentage of 10%,20%,30%,35%and40%,were used as modifiers to obtain the CO₂ adsorption material.With the increase of amine loading,the carbon dioxide adsorption capacity of KIT-6?T?-N,3N-KIT-6-X,3N-KIT-6?T?-N,PE-KIT-6?T?-N and PE-KIT-6?P?-N increased firstly and then decreased,which indicated that the amine modification in the range of a certain amount of load was helpful to improve the adsorption capacity of KIT-6 and PE-KIT-6 on carbon dioxide.When the mass ratio of 3N to KIT-6 was 1.5,3N-KIT-6-X has a maximum adsorption capacity of 3.017 mmol/g;when the TETA loading was 30%,KIT-6?T?-N,3N-KIT-6?T?-N and PE-KIT-6?T?-N obtained the maximum adsorption capacity of 1.438 mmol/g,2.063 mmol/g,1.871 mmol/g,respectively;when the TEPA loading was 35%,PE-KIT-6?P?-N has a maximum adsorption capacity of 2.9 mmol/g.The amine efficiency results showed that the adsorption efficiency of 3N-KIT-6?T?-N was between 3N-KIT-6-X and KIT-6?T?–N.The adsorption kinetics results show that the pseudo first order kinetic adsorption process can be fitted very well with the adsorption process for carbon dioxide by KIT-6 and PE-KIT-6,which indicates that the adsorption of carbon dioxide is only a simple physical adsorption;For the modified adsorbent,the Avrami model can well describe the adsorption process of carbon dioxide and the process of adsorbing the gas after the modified material is no longer a simple physical adsorption or a chemical adsorption than the result of the interaction of the two adsorption types.Four kinds of materials were selected for the five adsorption desorption cycle experiments and the results shows that the four kinds of materials had high regeneration performance.