A fast organic template-free, ZSM-11 seed-assisted synthesis of ZSM-5 with good performance in methanol-to-olefin
A fast organic template-free, ZSM-11 seed-assisted synthesis of ZSM-5 with good performance in methanol-to-olefin
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DOI：
10.1016/j.micromeso.2013.07.034
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发表时间：
2013-11
影响因子：
5.2
通讯作者：
Qingjun Yu;Xiaojing Meng;Jianwei Liu;Chunyi Li;Qiukai Cui
中科院分区：
文献类型：
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作者：
Qingjun Yu;Xiaojing Meng;Jianwei Liu;Chunyi Li;Qiukai Cui
通过在无模板体系中添加ZSM-11种子制备ZSM-5沸石，提出了一种新颖有效的制备方法。与传统的结晶时间为36 h的ZSM-5种子合成相比，ZSM-11种子在更短的时间内（12-16 h）驱动了ZSM-5的结晶。特别的是，在极短的时间内（12 h）可以得到许多大小为1-2 μm的ZSM-5小晶体。采用XRD、XRF、27Al - MAS - NMR、SEM、FTIR和n2吸附-脱附分析对种子分子筛和产物分子筛进行了表征。结果表明，ZSM-11种子颗粒表面末端Si-OH单元的存在是ZSM-5沸石快速结晶的主要原因。此外，种子提供的外表面面积通过为核的形成提供特定的位置，在加速成核率方面起着至关重要的作用。当应用于甲醇制烯烃（MTO）反应时，在分级zsm -11种子体系中获得的小ZSM-5晶体对C2= -C4 =烯烃具有高选择性和低失活率。总的来说，这条绿色合成路线为设计利用具有特殊性质的种子晶体合成性能良好的沸石提供了启示。
This work demonstrated a novel and efficient route for preparing ZSM-5 zeolite by adding ZSM-11 seeds in a template-free system. Compared to conventional ZSM-5-seeded synthesis using crystallization time of 36 h, ZSM-11 seeds drove the crystallization of ZSM-5 in much shorter time (12–16 h). Particularly, as used hierarchical ZSM-11 seeds with intergrowth morphology, numerous small ZSM-5 crystals with size of 1–2 μm could be obtained in a very short period (12 h). Both the seed and product zeolites were characterized by XRD, XRF,27Al MAS NMR, SEM, FTIR and N2adsorption–desorption analysis. It was found that the existence of terminal Si–OH units on the surface of ZSM-11 seed particles was principally responsible for the fast crystallization of target ZSM-5 zeolites. Moreover, the external surface area provided by the seeds played a vital role in accelerating the nucleation rate by offering specific sites for the formation of nuclei. When applied in the methanol to olefins (MTO) reaction, small ZSM-5 crystals obtained in the hierarchical ZSM-11-seeded system exhibited both a high selectivity to C2=–C4=olefins and a low deactivation rate. In general, this green synthesis route gives enlightenment for designing the synthesis of zeolites with good performance by using seed crystals with special properties.