Na-A型分级多孔分子筛的合成及吸水性能研究

Synthesis and Water Absorption Efficiency of Na-A HierarchicalPorous Molecular Sieves

LTA(Na-A)型分子筛具有规整的三维孔道结构、较高的比表面积和孔容,且对水分子有较高的吸附效率,因而被广泛用于工业领域的深度除湿。然而,尽管LTA型分子筛具有优异的吸附性能,但其在实际应用中再生温度较高(高于200℃)。因此,降低LTA型分子筛的脱附温度是进一步优化该类分子筛功能的有效手段。针对以上问题,采用分步水热法制备了具有分级多孔结构的LTA型分子筛,并研究了不同水热温度对分级多孔分子筛结构和性能的影响。结果表明,在100℃水热时,更容易得到结晶度更高、稳定性更好的LTA分子筛。所制备的分子筛在30℃,水分子吸附量达到0.304g·g-1。同时,TGA(热失重分析)显示在200℃时分子筛已脱出81%的吸附水分子,相比于普通分子筛的67%,脱附效率显著提升。

LTA(Na-A)zeolite has regular three-dimensional pore structure,high specific surface area and large pore volume,and high water-adsorption efficiency.Therefore,it is widely used in deep dehumidification in industry.Despite that,the regeneration temperature of LTA molecular sieve is normally higher than 200℃.As a consequence,reducing the desorption temperature of LTA molecular sieve is one of the major focuses for its functional optimization.LTA(Na-A)zeolites with mesopore-micropore hierarchical structure were prepared by using a step-by-step hydrothermal method.In addition,the effects of hydrothermal temperature on performance of the hierarchical porous zeolite were evaluated.It is found that,at hydrothermal temperature of 100℃,the synthesized LTA zeolites display promising crystallinity and stability.The water-adsorption capacity could reach 0.304 g·g−1 at 30℃.Meanwhile,TGA result indicates that desorption efficiency of the LTA zeolites is significantly improved,with 81%of the adsorbed water molecules than can be removed at 200℃,contrasting to 67%for the conventional Na-A zeolite.