Progress On Preparation And Properties Of Advanced Minerals-based Carbon Dioxide Capture Materials

Nowadays,greenhouse gases whose main member is carbon dioxide affect the global climate,human life and the environment significantly.The technologies of CO2 separation,capture,sequestration and usage have attracted widespread attention by international scientists,and the preparation of a highly efficient,economic,environmentally friendly,energy-saving,cost-effective CO2 capture materials remains an important issue to be solved.The research of advanced minerals-based CO2 eapture materials preparation methods and adsorption eapacities have such great significance to reduce the CO2 emissions.This paper focuses on the mechinisms to capture CO2 for two categories of materials:layered double hydroxides(LDHs)and solid amine adsorbents.We used X-ray diffraction(XRD),thermogravimetric analysis(TGA),N2 adsorption-desorption analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM)and other means to characterize CO2 capture materials and test the adsorption capacity of CO2.Firstly MgAlLDHs,CaAlLDHs,ZnAlLDHs,were synthesized by coprecipitation and calcined to obtain corresponding MgAlLDOs,CaAlLDOs,ZnAlLDOs.The results indicate that,LDHs has good layered structure.But LDOs form mesoporous structure with the different pore size instead of layered structure.The LDOs samples were tested under 200℃,400℃,600℃,and find LDOs are suitable for capturing C02 under the temperature at 200℃.Compared with MgAlLDOs,CaAlLDOs,ZnAlLDOs,the optimum adsorbent are ZnAlLDOs with adsorption capacity of 29.4mg/g.The reason has two parts:one is large physical adsorption capacity owing to their smaller pore size,the other is good chemical adsorption properties which attribute to stronger force between Zn ion and carbonate.Secondly,by using templates hydrothermal synthesis method,we prepared a series of MCM-41 and a series of SBA-15,and utilized two methods to modify Ca into mesoporous silicate:one was using the direct synthesis method to dope the Ca into silicate framework,the other was making Ca into silicate channel by impregnation.So full SiMCM-41,CaMCM-41,Ca-MCM-41,full SiSBA-15,CaSBA-15,Ca-SBA-15 have be prepared.Among them CaSBA-15 performs maximum CO2 adsorption capacity of 123mg/g(75℃),for chemical adsorption of Ca and its pore size.Finally,we loaded PEI into full SiMCM-41,CaMCM-41,Ca－MCM-41,full SiSBA-15,CaSBA-15,Ca-SBA-15 mesoporous silicates respectively to prepare corresponding solid amine adsorbents.Wherein the maximum adsorption amount is PEI/CaSBA-15 of 111mg/g(75℃).The solid amine adsorbents compared to the corresponding Ca modified mesoporous silicate have slightly lower adsorption capacity.But these materials have renewable and recycled properties that can make them more practical value.