| 摘要: |
| 以四丙基氢氧化铵为单模板剂，分别以硅酸或水玻璃为硅源，采用低温老化、高温晶化两段变温法合成球状多级孔ZSM-5分子筛；利用XRD、FT-IR、SEM、TEM以及氮气吸-脱附等手段对样品进行表征；并分析球状多级孔ZSM-5分子筛的形成机制。结果表明：所得多级孔ZSM-5分子筛产品主要由直径约为2 μm的规则球状颗粒所组成，而其颗粒内的晶间介孔和大孔主要来自于棒状纳米晶堆积而成的；与商业ZSM-5分子筛相比，该产品具有较高的相对结晶度，同时具有更大的BET总比表面积、介孔比表面积和介孔孔容，其中以硅酸为硅源合成的多级孔ZSM-5分子筛样品总比表面积、介孔比表面积和介孔孔容增加量分别达到114 m2/g、152 m2/g和0.094 cm3/g；低温老化阶段硅铝酸盐凝胶在四丙基铵根离子的诱导下首先形成大量纳米晶核，晶核接着在高温晶化阶段逐渐生长成纳米微晶，纳米微晶随后继续长大成棒状纳米晶体并自组装团聚成球状多级孔ZSM-5分子筛。 |
| 关键词: 多级孔ZSM-5分子筛 两段变温法 单模板剂 球状结构 |
| DOI：10.3969/j.issn.1673-5005.2018.02.019 |
| 分类号:O611.4 |
| 基金项目:国家自然科学基金项目（21776311）；中央高校基本科研业务费专项（15CX05030A）；应用表面与胶体化学教育部重点实验室开放课题基金项目（2017026） |
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| Two-step hydrothermal synthesis of hierarchical ZSM-5 zeolite with spherical structure using single template |
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WANG Youhe, WANG Xiaodong, SUN Hongman, REN Zihao, YAN Zifeng, JI Shengfu1,2
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1. College of Science in China University of Petroleum, Qingdao 266580, China;2. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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| Abstract: |
| Hierarchical ZSM-5 zeolites with spherical structure were successfully synthesized via a facile two-step hydrothermal process at low temperature aging and high temperature crystallization period, in which the water glass or silicic acid were selected as silicon source and the tetrapropylammonium hydroxide (TPAOH) was used as the single template. The zeolites were characterized with XRD, FT-IR, N2 adsorption-desorption isotherms, SEM and TEM, through which the formation mechanism of the hierarchical ZSM-5 zeolites with spherical structure was investigated. The results indicate that the hierarchical ZSM-5 zeolite consists of regular spherical particles with around 2 μm in diameter and possesses intercrystalline meso-and macropores generated from the aggregation of bar-shape ZSM-5 nanocrystals. Compared with commercial ZSM-5 zeolite, the as-synthesized products with high relative crystallinity have larger BET specific surface area, mesopore surface area and mesopore volume. And the increasing amounts of the above three parameters for hierarchical ZSM-5 zeolites synthesized with silicic acid as silicon source are reached 114 m2/g, 152 m2/g and 0.094 cm3/g, respectively. It is proposed that the aluminosilicate gel forms nano nuclei firstly with the induction effect of TPA+ at the low temperature aging stage. Then, the crystal nucleus grew gradually to become nanocrystalline under the high temperature crystallization process. Finally, the aggregated nanocrystalline continues to grow up into bar-shape ZSM-5 nanocrystals and self-assemble into regular spherical structure. |
| Key words: hierarchical ZSM-5 zeolites two-step hydrothermal method single template spherical structure |
