層狀水滑石的合成、再生與對二氧化碳之吸附研究

Abstract

針對二氧化碳捕捉技術中高溫吸附材料的研究，本文將分為兩大部分。第一部分為合成不同Ca/Fe-NO3莫耳比例之層狀水滑石材料，以XRD、SEM進行結構鑑定及表面型態觀察，再利用TGA於不同溫度環境測量其二氧化碳吸附量，其中，CaFe-NO3其吸附溫度介於600-800oC之間，並且經過多次吸脫附迴圈，二氧化碳之吸附量並無嚴重減少。除此之外，不同陰離子根之CaFe-CO3亦被成功的合成出來，其與NO3最大之差異為層間距的變化，以及擁有較快的吸附動力；並且同樣具有穩定之二氧化碳吸脫附迴圈。 第二部分為CaAl-LDH以及CaFe-LDH的再生條件因子的探討，其中當再生為20 mL純水室溫下反應12小時之條件，將有最佳之結構回復結果，除此之外，以TGA進行多次二氧化碳吸脫附迴圈測試，經過再生之樣品擁有穩定的吸脫附迴圈，而當再生條件為0.5 mL純水室溫下反應12小時的樣品，其吸附量將回復到與原始相似。同時本研究亦發現，結構再生的過程中，水溶液為結構重組之驅動力。

Calcium based layer double hydroxides (LDHs) are good adsorbent candidate for captureing carbon dioxde (CO2) at high temperature. In this study, first, Calcium and iron containing layer double hydroxides (CaFe-LDHs) with different molar ratio were synthesized. The layer structure and the morphology of material have been characterized by XRD and SEM. TGA was used to test for the sorption of CO2 at different temperature. We observed CaFe-NO3-LDH has high CO2 sorption capacities in high temperature range from 600-800oC, and furthermore these materials have stable CO2 capture capacity during carbonation/calcination cycles. Different kind of anion CaFe-CO3-LDHs has also been synthesized. The adsorption kinetic of CaFe-CO3-LDHs is faster than CaFe-NO3-LDHs, and same as CaFe-NO3-LDHs the capacity is stable during CO2 capture carbonation/calcination cycles. The Second parts of this study, many kinds of condition which effects regeneration of CaAl-LDH and CaFe-LDH have been observed. While the regeneration solution is deionized water 20mL, and reaction at room temperature for 12 hours, the reconstruction of LDH structure would be better. After regeneration process, the stability of CO2 capture capacity during carbonation/calcination cycles is quite stable. Moreover, when the regeneration of solution is 5mL, the sorption capacity of CO2 would be good as initial LDH. During the regeneration process, aqueous solution is the driving force for the structure reconstruction.