Adsorption Properties Of CO₂on Cyclodextrin-based Porous Materials

In order to alleviate the global warming caused by the greenhouse effect,carbon dioxide emission reduction technology is a problem that must be overcome.Carbon dioxide emission reduction technologies include source control,process control and end control,among which end control is the most widely used.The most commonly used carbon dioxide separation and capture technologies include adsorption,absorption and membrane separation.Adsorption method has the advantages of low cost,mild operation conditions,low energy consumption,stable performance,high adsorption efficiency and good selectivity,which is an important technical direction to solve the problem of carbon dioxide emission in the future.Preparation of a kind of adsorbent with high adsorption capacity,strong selectivity and stable performance is the key to the success of carbon dioxide capture by adsorption method.In this paper,the carbon dioxide adsorption characteristics ofβ-CD porous materials were studied.A series of porousβ-CD adsorption materials were prepared by changing the activation temperature and heating rate.The effects of various conditions on the gas adsorption characteristics of the materials were studied.The pore structure,surface groups,morphology,surface element content and gas adsorption capacity of the materials were characterized by bet,FTIR,SEM-EDS and static adsorption.Combined with the adsorption capacity of adsorption materials at different temperatures,the thermodynamic analysis of adsorption process was carried out by using thermodynamic formula.The characteristic reactions in the activation process ofβ-CD were studied by TG-DTA and TG-IR,and the activation path ofβ-CD was found.According to the activation path,the pore forming mechanism ofβ-CD was explored.The results show that higher activation temperature and lower heating rate are beneficial to the carbonization process ofβ-CD,that is to say,the gas adsorption performance of the adsorbent can be improved under this condition,but the sample loss will also be increased.By analyzing the thermodynamic properties of the adsorption materials,it is found that the adsorption process ofβ-CD materials for CO₂is an exothermic and physical adsorption process;Based on path tracing,it is considered that the pyran ring inβ-CD molecule is mainly dehydrated by C3-C4 dehydroxylation.