Stepwise gel preparation for high-quality CHA zeolite synthesis: A common tool for synthesis diversification
Stepwise gel preparation for high-quality CHA zeolite synthesis: A common tool for synthesis diversification
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用于高质量 CHA 沸石合成的逐步凝胶制备：合成多样化的常用工具
DOI：
10.1021/acs.cgd.8b00963
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发表时间：
2018
影响因子：
3.8
通讯作者：
T. Sano
中科院分区：
文献类型：
--
作者：
Y. Joich;D. Shimono;N. Tsunoji;Y. Takamitsu;M. Sadakane;T. Sano
铝硅酸盐分子筛在工业过程中被广泛使用，主要作为催化剂或吸附剂，并且仍然需要在合成方面取得进展以促进进一步的应用。为了进一步扩大沸石合成系统，在这里，我们报告的合成凝胶的分步制备，通过分开的组成控制，这种策略被施加到一个CHA沸石的有效合成中存在的廉价的有机结构导向剂（OSDA），苄基三甲基铵。与传统的一步凝胶制备方法相比，以更高的结晶速率制备了高度结晶的纳米尺寸CHA沸石。逐步方法还提供了在宽范围的起始凝胶组合物中的CHA沸石，并且可以调节所形成的CHA内的铝含量。铝硅酸盐形成过程中，包括X-射线衍射法，NMR和拉曼光谱，和电喷雾电离质谱（ESI-MS）和几个合成实验的组合分析方法研究，揭示了铝硅酸盐簇，形成在高碱性富铝中间体凝胶在分步方法有助于有效地形成CHA沸石在最后的合成步骤。我们还证明了这种策略适用于具有不同OSDA和目标沸石的其他合成系统。此外，逐步方法提供了具有高活性和耐久性的有效沸石催化剂用于排放气体净化应用。这种可共享的概念有望成为一种通用工具，为各种沸石合成系统带来额外的合成多样性。
Aluminosilicate molecular-sieve zeolites are widely used in industrial processes, mostly as catalysts or adsorbents, and advances in the synthesis are still required in order to progress further applications. To further expand the zeolite synthesis system, herein we report the stepwise preparations of synthesis gels through divided compositional control; this strategy is applied to the effective synthesis of a CHA zeolite in the presence of an inexpensive organic structure directing agent (OSDA), benzyltrimethylammonium. Highly crystalline nanosized CHA zeolites were prepared at higher crystallization rates compared to those prepared using the conventional one-step gel-preparation method. The stepwise method also provided CHA zeolite in a wide range of starting gel compositions, and aluminum content within the formed CHA could be tuned. The aluminosilicate-formation process, investigated by the combination of analytical methods including X-ray diffractometry, NMR and Raman spectroscopy, and electrospray-ionization mass spectrometry (ESI-MS) and several synthetic experiments, revealed that the aluminosilicate cluster that forms in the highly alkaline aluminum-rich intermediate gel during the stepwise method helps to effectively form the CHA zeolite in the final synthesis step. We also demonstrate that this strategy is applicable to other synthesis systems with different OSDAs and target zeolites. Furthermore, the stepwise method provides efficient zeolite catalysts with high activities and durabilities for emission-gas purification applications. This sharable concept is expected to become a common tool that brings additional synthetic diversity to a variety of zeolite-synthesis systems.