Modification Of CaO Based CO₂ Adsorbent And Its Promoting Mechanism Study

As a greenhouse gas,CO₂ has attracted worldwide attention,and its capture,utilization and storage has become a hot topic in current research.However,no matter for CO₂ conversion and utilization or storage and fixation,its capture is a necessary prerequisite.For CaO adsorbents,due to its low price,rich content and high theoretical adsorption value,has attracted more attentions in the field of high-temperature CO₂ adsorption.However,CaO still has problems such as low adsorption capacity and poor cycling stability due to excessive particle size.Based on this,the molten salt/CaO adsorbent was constructed and its properties were studied in depth.In order to optimize the CaO material loaded with carbonic acid fused salt,this paper systematically discussed the influence of components,proportion and load of molten salt on the adsorption performance of composite materials,and found that CaO loaded with 7.5 mol%?Li-K?2CO3 had the best adsorption effect.At the same time,the optimal adsorption conditions and the cyclic stability of the optimized adsorbent were selected,and the feasibility of the material in practical application was comprehensively evaluated.In this paper,the adsorption effects of CaO loaded with three kinds of mixed alkali salts at high temperature were compared,and the structure and morphology of CaO adsorption materials were investigated.It is found that both partially mixed carbonate and chloride can form molten state at high temperature,but their effects on CaO adsorption are completely opposite.Finally,the key factor affecting the adsorption effect of molten salt is O₂-conductivity in molten salt by combining electrochemical analysis,which provides a guiding standard for the subsequent selection of molten salt.In this paper,a new solvent/nonsolvent method was developed to solve the problem that CaO material is easy to be sintered and deactivated in the high temperature adsorption-desorption cycle,and CaO adsorbent with MgO as the supporting layer was successfully prepared by this method.It was found by SEM that the two solid phases of the material were mixed evenly,and as synthesized MgO/CaO had a good cycling stability effect.In this method,the target material is gelled from the solution mainly through the effect of solvent and nonsolvent,and then the gel is directly calcined to produce the mixed material This preparation method avoids the problem of uneven mixing caused by the crystallization process in traditional mixing methodsThis article also explores the types of hydrotalcite as support materials,the feasibility of CaO,the results show that CaAl hydrotalcite after high temperature calcination temperature tower,the formation of CaO and Ca12Al14O33,because of the special type of hydrotalcite structure,uniform Cai2Al14O33 mixed with CaO,period show a good effect of stripping absorption,and as the support material can effectively prevent CaO sintering.But traditional hybrid method is difficult to ensure that two kinds of materials are scattered,and may lead to a bad cyclic performance.In this paper,we report a sintering-resisted CaO prepared by solvent/nonsolvent method using CaAl hydrotalcite as supported material,when the CaAl LDH content is 20 wt%,The decreasing of CO₂ uptake is only 3.5%after 10 adsoption/desorption cycles,and for CaO without supported materials,the decreasing of CO₂ uptake is only 48%.