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Synthesis, characterization, and catalytic application of hierarchical nano-ZSM-5 zeolite

机译：层次纳米ZSM-5沸石的合成，表征和催化应用

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Hierarchical nano-ZSM-5 zeolites (Z5- X ) with different grain sizes were synthesized by varying amounts of 3-glycidoxypropyltrimethoxysilane (KH-560) in the hydrothermal synthesis strategy. Moreover, the conventional ZSM-5zeolite(Z5), which was prepared without KH-560, was used as the reference sample. The crystalline phases, morphologies, porous characteristics, Si/Al molar ratios and acidic properties of all fresh catalysts were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), N _(2) adsorption–desorption, inductively coupled plasma atomic emission spectroscopy (ICP) and temperature programmed desorption of ammonia (NH _(3) -TPD) techniques. Results show that the grain size and strong acid amount of zeolite decreased with the increasing amount of KH-560. The micropore surface areas and the corresponding volume of Z5- X changed less compared with Z5. Consequently, the high shape-selectivity of zeolite was preserved well under the addition of KH-560. However, the mesopore surface areas and the corresponding volume increased significantly with the increasing amount of KH-560. Benefiting from the abundant hierarchical structure, the Z5- X catalysts exhibited a larger coke capacity than the Z5 catalyst. The coke depositions of all the deactivated catalysts were characterized by the thermogravimetric technique (TG), and the results are indicative of the decreased average rate of coke deposition with an increasing amount of KH-560, which could result from the gradually reduced strong acid amount and the nano-sized crystallites. The catalytic performance of methanol-to-aromatics (MTA) indicates that the Z5-0.12 catalyst exhibited higher catalytic activity and selectivity of BTX as the reaction was prolonged, which could result from the synergistic effect among the proper strong acid amount, the smaller zeolite grain size, and the abundant hierarchical structure.
机译：通过在水热合成策略中改变3-丙酸氧基丙基三甲氧基硅烷（KH-560），合成具有不同晶粒尺寸的分层纳米ZSM-5沸石（Z5- X）。此外，使用在没有KH-560的情况下制备的常规ZSM-5沸石（Z5）作为参考样品。使用X射线衍射（XRD），傅立叶变换红外光谱（FT-IR），扫描电子显微镜（SEM），表征所有新鲜催化剂的结晶相，形态，多孔特性，Si / Al摩尔比，Si / Al摩尔比和酸性特性， N _（2）吸附 - 解吸，电感耦合等离子体原子发射光谱（ICP）和温度编程氨（NH _（3）-TPD）技术。结果表明，随着KH-560的增加，晶粒尺寸和沸石的强酸量减少。与Z5相比，微孔表面区域和相应体积的Z5- x变化较少。因此，在添加KH-560，沸石的高形状选择性良好。然而，中孔表面区域和相应的体积随着KH-560的增加而显着增加。从丰富的层次结构受益，Z5- x催化剂表现出比Z5催化剂更大的焦炭能力。所有停用催化剂的焦炭沉积的特征在于热重量技术（Tg），结果表明，随着逐渐降低的强酸量导致的kH-560的焦炭沉积的平均速率降低和纳米尺寸的微晶。甲醇 - 芳烃（MTA）的催化性能表明，Z5-0.12催化剂表现出较高的催化活性和BTX的选择性，因为反应延长，这可能是由合适的强酸量的协同作用，较小的沸石产生较小的沸石晶粒尺寸和丰富的等级结构。

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