水热碱蚀与碱溶滤联合处理制备介孔丝光沸石  

Mesoporous Mordenites Obtained by Sequential Hydrothermal Alkaline Etching and Alkaline Leaching Treatments

作　　者：杜夏梅[1] 谷迎秋[2] 孙月桥[1] 徐丽颖[1] 金英杰[1,2] 

机构地区：[1]辽宁石油化工大学化学与材料科学学院 [2]辽宁石油化工大学石油化工学院,辽宁抚顺113001

出　　处：《硅酸盐学报》2013年第9期1198-1206,共9页Journal of The Chinese Ceramic Society

基　　金：辽宁省自然科学基金(200922180);国家自然科学基金(2117-1083)资助项目

摘　　要：以硅酸钠溶胶和铝酸钠为硅、铝源,采用水热合成和离子交换法制备了质子型丝光沸石（H-MOR）。研究水热碱蚀与碱溶滤联合处理对H-MOR改性样品的介孔结构、晶体形貌、组成及酸性质的影响。结果表明：用初始浸渍液对H-MOR进行水热碱蚀,H-MOR骨架脱硅选择性高,晶体含有均一的筛状介孔;水热碱蚀与一次碱溶滤处理的样品具有尺度分布较窄的槽形介孔,沸石骨架硅铝比降低而介孔率增加;再度进行碱溶滤处理,沸石的最可几介孔尺寸和累计介孔体积进一步增大,而残留抽出物（无定形SiO2–Al2O3）的硅铝比为生成介孔丝光沸石晶相的5倍以上。联合碱处理的丝光沸石样品具有骨架脱硅选择性和介孔率高、介孔分布（4.4～5.7nm）可控的特性,其结晶度、固有微孔结构和酸性质退化程度较低。Mordenites （MOR） were firstly synthesized using sodium silicate sol and sodium aluminate as silica and alumina sources by a hydrothermal method, and then treated by subsequent ion exchange and calcination. The mesopore-modified MOR samples de-rived from the protonated MOR （H-MOR） were prepared by a united alkaline-treated process, i.e., the combination of hydrothermal alkaline etching and subsequent alkaline leaching. The alkaline-treated H-MOR samples were characterized to investigate the com-bined treatment impacts on the mesopore structure/texture, crystal morphology, and compositional and acidic properties. The results reveal that the purely hydrothermal alkaline etching via incipient wetness impregnation provides a high selectivity for zeolite frame-work desilication, leading to the formation of uniform mesopores with the sieve texture of the treated MOR crystals. The combination of hydrothermal alkaline etching and alkaline leaching facilitates the formation of narrower sized slit-like mesopores with the en-hanced mesoporosity and the decreased framework Si/Al ratios. The further alkaline leaching towards the sample can improve the mesopore size and volume. In addition, the combined alkaline treatment can increase Si/Al ratios of extracted amorphous SiO2-Al2O3 up to more than 5 times, compared to the mesoporous MOR formed. The combined treatment approach to introduce mesopores into MOR crystals is thus efficient to selectively remove Si from zeolite framework and to develop a high mesoporosity with the mesopore distribution in the size range from 4.4 to 5.7 nm. However, there is no considerable loss in the zeolitic crystallinity, the microporous structure and the intrinsic acidity.

关 键 词：丝光沸石 联合碱处理 水热碱蚀 介孔率 孔径分布 

分 类 号：O643[理学—物理化学]