Full-crystalline hierarchical monolithic ZSM-5 zeolites as superiorly active and long-lived practical catalysts in methanol-to-hydrocarbons reaction
Full-crystalline hierarchical monolithic ZSM-5 zeolites as superiorly active and long-lived practical catalysts in methanol-to-hydrocarbons reaction
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全结晶分级整体 ZSM-5 沸石作为甲醇制烃反应中活性优异且寿命长的实用催化剂
DOI：
10.1016/j.jcat.2016.05.009
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发表时间：
2016-08-01
影响因子：
7.3
通讯作者：
Xie, Zaiku
中科院分区：
文献类型：
--
作者：
Zhou, Jian;Teng, Jiawei;Xie, Zaiku
如果考虑到工业应用中必要的机械强度要求，要获得性能优越、活性高且使用寿命长的实用沸石催化剂，就必须基于成型体而非仅仅是粉末。粘结剂作为保持宏观物体完整不可或缺的添加剂，其本身无催化活性，并且它们在传质方面的负面影响被广泛忽视。在此，我们首次揭示了在成型沸石催化剂中加入硅溶胶作为粘结剂会显著抑制传质。然后，通过在可控有机模板蒸汽的辅助下对成型的粘结剂/沸石体进行重结晶，粘结剂转化为沸石相，形成了全沸石整体材料。在重结晶过程中，发现原位生成了明显的晶内介孔，同时保持了较高的机械强度。这种多级结构的整体材料显示出显著的传质优势，这意味着重结晶后更多的酸位点可被利用。因此，在性能评估中，多级结构的全沸石整体材料在C4烯烃裂解反应中表现出更高的丙烯产率和更慢的失活速率。此外，在工业条件下催化甲醇制烃（MTH）时，实现了极长的循环时间，超过2000小时，是商业催化剂的三倍。这是关于在甲醇转化反应中无需再生且使用寿命如此之长的沸石催化剂的首次报道。对整体材料重结晶的基本理解将对开发更多高价值的适用催化剂以及优化现有沸石催化剂的技术进步做出重大贡献。（C）2016爱思唯尔公司。保留所有权利。
The efforts to obtain superior active and long-lived practical zeolite catalysts must be based on shaped forms rather than only powder, if considering necessary mechanical strength requirement in industrial application. The binders, incorporated as indispensable additives to keep intact of macroscopical body, are catalytically inert and their negative impacts in mass transfer are widely neglected. Here, we firstly revealed the remarkable mass transfer depression by incorporating silica sol as binders in shaped zeolitic catalyst. Then, by re-crystallizing the shaped binder/zeolite body with assistance of controlled organic template steam, the binders were converted into zeolitic phase, forming full-zeolitic monoliths. In re crystallization, it was found obvious intra-crystalline mesopores were in situ created while maintaining high mechanical strength. A remarkable mass transfer advantage was revealed in such hierarchical monolith, which means more acid sites will be accessible after re-crystallization. Therefore, in performance evaluation, hierarchical full-zeolitic monolith demonstrated higher propylene yield and slower deactivation rate in C4 olefin cracking reaction. Moreover, highly prolonged cycle time, which was more than 2000 h and three times as long as that of commercial catalyst, was realized in catalyzing methanol to-hydrocarbons (MTH) under industrial condition. That is the first report on so long-lived zeolite catalyst without regeneration in methanol conversion reaction. Fundamental understanding in re-crystallization of monolithic material will contribute significantly to technical progress in developing more high-valued applicable catalysts and optimizing existing zeolite catalyst. (C) 2016 Elsevier Inc. All rights reserved.