水热碱蚀与碱溶滤联合处理制备介孔丝光沸石_中国硅酸盐学会 - 精品期刊
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水热碱蚀与碱溶滤联合处理制备介孔丝光沸石
2013-11-14 | 编辑:enablesite | 【

杜夏梅1,谷迎秋2,孙月桥1,徐丽颖1,金英杰1,2
(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)

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(4.4~5.7 nm)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。

关键词:丝光沸石;联合碱处理;水热碱蚀;介孔率;孔径分布
中图分类号:O643    文献标志码:A    文章编号:0454–5648(2013)09–1198–09
网络出版时间:2013–08–29  11:49:04    网络出版地址:http://www.cnki.net/kcms/detail/11.2310.TQ.20130829.1149.006.html

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

DU Xiamei1,GU Yingqiu2,SUN Yueqiao1,XU Liying1,JIN Yingjie1,2
(1. School of Chemical and Material Science; 2. School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001, Liaoning, China)

Abstract: 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 derived 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 combined 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 framework 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 enhanced 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.

Key words: mordenite; united alkaline treatment; hydrothermal alkaline etching; mesoporosity; pore size distribution

 

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