Seed-Assisted Synthesis of ZSM-5 Aggregates Assembled from Regularly Stacked Nanosheets and Their Performance in n-Hexane Aromatization
Seed-Assisted Synthesis of ZSM-5 Aggregates Assembled from Regularly Stacked Nanosheets and Their Performance in n-Hexane Aromatization
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DOI：
10.1021/acs.iecr.1c01894
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发表时间：
2021-08
影响因子：
4.2
通讯作者：
Zhanggui Hou;Xiaotong Mi;Xiaoguo Li;Hongtao Liu
中科院分区：
文献类型：
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作者：
Zhanggui Hou;Xiaotong Mi;Xiaoguo Li;Hongtao Liu
具有短直孔道结构的HZSM-5分子筛在石油化工过程中具有易扩散、不易生焦等优点。本工作以硅酸盐-1为晶种，合成了由规则排列的纳米片状晶体组装而成的ZSM-5分子筛，其ab轴厚度约为60 nm。与传统的硅酸盐-1（S-1：正硅酸乙酯（TEOS）作为硅源和四丙基氢氧化铵（TPAOH）作为SDA）相比，使用相对较低成本的硅溶胶作为硅源、四丙基溴化铵（TPABr）作为结构导向剂（SDA）和乙胺作为助剂来合成硅酸盐-1（S-2）。当在合成体系中加入S-2晶种时，在乙胺的辅助下，晶种可以限制晶体沿沿着b轴方向的生长。同时，相邻的ZSM-5纳米片晶体会自发地堆叠在一起。Zn/S-2-1催化剂用于正己烷芳构化反应时，与以S-1为晶种合成的催化剂相比，具有较高的正己烷转化率和苯、甲苯、乙苯、二甲苯（BTEX）的选择性以及催化稳定性。本工作为纳米片催化剂组装的ZSM-5聚集体在烃类芳构化反应中的应用开辟了新的前景。
HZSM-5 crystals with short straight channels possess the advantages of easier diffusion and less coke formation in petrochemical processes. In this work, aggregated ZSM-5 zeolite assembled by regularly stacked nanosheet-like crystals with ab-axis thickness of 60 nm was synthesized using specially designed silicate-1 as seed. Silicate-1 (S-2) was synthesized using relatively lower cost silica sol as a silica source, tetrapropylammonium bromide (TPABr) as a structure-directing agent (SDA), and ethylamine as an assistant compared with traditional silicate-1 (S-1: tetraethyl orthosilicate (TEOS) as a silica source and tetrapropylammonium hydroxide (TPAOH) as an SDA). When S-2 seeds were added into the synthesis system, the seeds could limit the crystal growth along theb-axis direction under the assistance of ethylamine. Meanwhile, the adjacent ZSM-5 nanosheet crystals would spontaneously stack together. The catalyst Zn/S-2-1 exhibited relatively highern-hexane conversion and selectivity of benzene, toluene, ethylbenzene, and xylene (BTEX) as well as catalytic stability in contrast to the catalyst synthesized using S-1 as seed when being used in then-hexane aromatization reaction. This work opened up a new prospective for ZSM-5 aggregates assembled from the nanosheet catalyst design in the application of hydrocarbon aromatization.