石英论文：Li_4SiO_4的合成及其高温吸收CO_2性能研究.docVIP

石英论文：Li_4SiO_4的合成及其高温吸收CO_2性能研究 【中文摘要】近年来,温室效应以及由其引起的环境变化受到越来越多的关注,CO2的捕获、分离与封存成为遏制C02排放,减少大气中C02浓度的有效方法之一。Li4SiO4作为高温下(500℃-720℃)循环吸收CO2的优良吸收剂,用于化石燃料电厂及相关的密集C02排放源,具有很大的应用前景。因此,研究Li4SiO4的合成及其吸收-解吸CO2性能,在环境和经济领域具有重要的意义。本论文以石英(SiO2)、正硅酸乙酯(TEOS, C8H20O4Si)和煤矸石作为硅源,以Li2CO3和LiOH·H2O为锂源,分别采用固相法、溶胶-凝胶法和水热法合成Li4SiO4,并研究了其在高温下的CO2吸收-解吸性能。以XRD、SEM、热分析(DSC-TG和DTA-TG)为表征和测试手段,对Li4SiO4的合成方法、反应动力学、样品形貌、粒度和吸收CO2性能等做了系统研究,具体分为如下四部分：(1)以石英(Si02)和Li2CO3为原料,采用传统固相法,研究了原料配比(n(Li+):n(Si4+)=4:1-4.4:1)、反应温度(500-1000℃)、石英粒度(75-180μm,45-75μm, 38-45μm和小于38μm)对Li4SiO4合成的影响规律。发现石英粒径小于38μm时,在800℃煅烧4h可合成出纯Li4SiO4其C02最大吸收率为31.3wt%。(2)将煤矸石进行煅烧、酸浸、洗涤、干燥等预处理后,所得产物与Li2CO3在800℃煅烧4h合成出Li4SiO4样品。煤矸石经过600℃煅烧等预处理后,所制样品的最大CO2吸收率最高,达到20.9wt%；而直接利用未经过预处理的煤矸石合成的样品,其最大CO2吸收率最低,仅为16.4wt%。(3)以TEOS为硅源,在碱性条件下通过TEOS水解合成包裹于Li2CO3表面的Si02凝胶,将其在600℃、650℃和700℃煅烧6h后合成Li4SiO4。结果表明,经过700℃煅烧合成的Li4Si04,CO2的最大吸收率最高,达到了32.9wt%。(4)以TEOS为硅源,LiOH·H2O为锂源,采用水热反应得到Li2SiO3和Li2CO3的复合粉体,再在700℃煅烧4h可合成出Li4SiO4。结果发现,当水热反应过程中添加CTAB时,所合成的Li4SiO4样品在低温时的CO2吸收率较高,但其C02最大吸收率较低(31.9wt%)；当不添加CTAB时,所得Li4SiO4样品的最大吸收率高达34.3wt%。 【英文摘要】In recent years, the environment change which is resulted from greenhouse effect has attached more and more attention. CO2 capture and sequestration is an effective way to reduce its release to the atmosphere and curb the greenhouse effect. As an excellent adsorbent material for CO2 capture at high temperature(500℃-720℃), Li4SiO4 applied in the large stationary sources like fossil fired power stations and related industries has a promising future. Therefore, it is significant to investigate the synthesis and CO2 adsorption-desorption performance of Li4SiO4, especially in the area of environment and economy.In this paper, quartz (SiO2), TEOS and coal gangue were chosen as silicon sources to synthesize Li4SiO4, while Li2CO3 and LiOH稨2O as lithium sources. X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (DSC-TG and DTA-TG) were used as test and characterization methods. The method and kine