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首页> 外文学位 >In situ studies of the thermal evolution of the structure and sorption properties of magnesium-aluminum-carbonate layered double hydroxide.
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In situ studies of the thermal evolution of the structure and sorption properties of magnesium-aluminum-carbonate layered double hydroxide.

机译：原位研究碳-铝-碳酸镁层状双氢氧化物的结构热演化和吸附性能。

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摘要

Several in situ techniques have been used to investigate the thermal evolution of the structure of Mg-Al-CO3 layered double hydroxide under inert atmosphere. Based on the results of the study, a model was proposed to describe the structural evolution of the Mg-Al-CO3 LDH. The sorption characteristics and thermal reversibility of Mg-Al-CO3 LDH were also investigated with in situ techniques under both inert and reactive atmospheres. The experimental observations are shown to be consistent with the structural model proposed. The structure, sorption characteristics, and thermal reversibility of Mg-Al-CO3 LDH materials are important in their use for the high temperature applications.; Diffusivity constants and adsorption isotherms for carbon dioxide in Mg-Al-CO3 LDH were investigated by the gravimetric method at elevated temperatures. The experimental estimates of diffusivity constants and those obtained by molecular dynamic simulations are in good qualitative agreement. The experimental adsorption isotherms for CO2 in LDH have been studied with the Langmuir isotherm equation and various empirical adsorption isotherm equations. It is observed that the heterogeneity of the system and the interaction between CO2 and Mg-Al-CO3 LDH increases with temperature. Particle size effect on CO2 uptake and adsorption isotherm was also investigated. It was observed that both the amount of CO 2 uptake and BET surface area increases as the particle size decreases. When the uptake amount was normalized with BET surface area, the uptake amount was fairly constant for all the ranges of particle sizes.; Various methods for the preparation of LDH membranes were studies, and the transport properties of prepared membranes were investigated. The values of separation factor were similar to Knudsen factor, and, to prepare perm-selective microporous LDH membranes, it is required to find an effective binder or a method for LDH crystals to intergrow each other.
机译：几种原位技术已被用来研究惰性气氛下Mg-Al-CO3层状双氢氧化物结构的热演化。根据研究结果，提出了一个模型来描述Mg-Al-CO3 LDH的结构演变。在惰性和反应性气氛下，还采用原位技术研究了Mg-Al-CO3 LDH的吸附特性和热可逆性。实验结果表明与提出的结构模型是一致的。 Mg-Al-CO3 LDH材料的结构，吸附特性和热可逆性在高温应用中很重要。在高温下，通过重量分析法研究了Mg-Al-CO3 LDH中二氧化碳的扩散常数和吸附等温线。扩散常数的实验估计和通过分子动力学模拟获得的估计定性一致。利用Langmuir等温方程和各种经验吸附等温方程研究了LDH中CO2的实验吸附等温线。观察到系统的异质性以及CO2和Mg-Al-CO3 LDH之间的相互作用随温度增加。还研究了粒径对CO 2吸收和吸附等温线的影响。观察到随着颗粒尺寸减小，CO 2吸收量和BET表面积均增加。当摄取量用BET表面积标准化时，在所有粒径范围内摄取量都相当恒定。研究了制备LDH膜的各种方法，并研究了制备的膜的传输性能。分离因子的值与Knudsen因子相似，并且为了制备渗透选择性微孔LDH膜，需要找到一种有效的粘合剂或LDH晶体相互生长的方法。

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  • 作者

    Kim, Yongman.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 191 p.
  • 总页数 191
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化工过程（物理过程及物理化学过程）;
  • 关键词

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