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以硝酸锂、正硅酸乙酯等为原料,利用溶胶-凝胶法制备了硅酸锂高温CO2吸附材料,利用XRD考查了制备方法对样品物相的影响;通过程序升温、定温吸附测试对样品的CO2吸附性能进行了表征,并利用原位红外光谱技术初步分析了CO2在硅酸锂表面的吸附过程。结果表明,在硝酸锂-正硅酸乙酯-乙醇共水解体系中引入添加剂柠檬酸,可获得纯度在90%以上的单斜相硅酸锂。所制备的样品在2%CO2-He气氛下,450—500℃温度区间具有较好的吸附性能。低温下CO2吸附在碳酸锂表面,主要以碳酸氢盐形式存在,高温下主要以离子碳酸盐及卧式吸附碳酸盐等形式存在。
Lithium silicate and tetraethyl orthosilicate were used as raw materials to prepare high-temperature lithium silicate adsorbent by sol-gel method. The influence of preparation method on the phase of the sample was investigated by XRD. The CO2 adsorption performance of the sample was characterized and the adsorption process of CO2 on the surface of lithium silicate was preliminarily analyzed by in situ FTIR spectroscopy. The results showed that monocrystalline monoclinic lithium silicate with purity over 90% can be obtained by introducing citric acid additive into lithium nitrate - TEOS - ethanol system. The prepared sample has better adsorption performance in the temperature range of 450-500 ℃ under 2% CO2-He atmosphere. Low temperature CO2 adsorption on lithium carbonate surface, mainly in the form of bicarbonate, high temperature mainly in the form of ionic carbonate and horizontal adsorption of carbonates exist.