Mg-Al-CO_3与Zn-Al-CO_3水滑石热稳定性差异的研究

层状双金属氢氧化物（ Layered double hydroxides,简称 LDHs）是一类近年来发展迅速的阴离子型粘土，又称水滑石，其组成通式为： [M? 1-xM? x(OH)2]x＋ Ax/nn-mH2O，其中 M?是二价金属离子， M?是三价金属离子， An－是阴离子。这种材料是由相互平行的层板组成，层板带有永久正电荷；层间具有可交换的阴离子以维持电荷平衡。通过离子交换可在层间嵌入不同的基团，制备许多功能材料，被广泛用作催化剂、吸附剂及油田化学品等，已引起人们的关 注 [1～ 4]。有关 Mg-Al-CO3与 Zn-Al-CO3水滑石的合成及性能研究国内外已有大量报道 [1…

Study of the Differences of Thermal Stability of Mg-Al-CO3 and Zn-Al-CO3 Hydrotalcite

The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD, IR and TG-DTA. Although both have the same crystal structures, their thermal stabilities are quite different. During the thermal decomposition process, Mg-Al-CO3 hydrotalcite exhibits two stepsdesorption of interlayer water occurs at 200℃, followed by dehydroxylation of the brucite-like layers and loss of carbonate at 400℃, Zn-Al-CO3 hydrotalcite decomposes in one step-the desorption of interlayer water, structural water and carbon dioxide occurred at the same time at 200℃. The results of a theoretical study indicate that the bond strengths of OH-CO3-OH and OH-H2O-CO3-OH in Mg-Al-CO3 hydrotalcite are stronger than those in Zn-Al-CO3 hydrotalcite. It has been shown that the thermal stability of Mg-Al-CO3 hydrotalcite is higher than that of Zn-Al-CO3 hydrotalcite