Ultrafast and Continuous Flow Synthesis of Silicoaluminophosphates

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• 作者：Zhendong Liu ; Toru Wakihara ; Naoki Nomura ; Takeshi Matsuo ; Chokkalingam Anand ; Shanmugam P. Elangovan ; Yutaka Yanaba ; Takeshi Yoshikawa ; Tatsuya Okubo
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：July 12, 2016
• 年：2016
• 卷：28
• 期：13
• 页码：4840-4847
• 全文大小：518K
• 年卷期：0
• ISSN：1520-5002

文摘

Silicoaluminophosphates are a class of crystalline microporous materials that have been widely used as catalysts and adsorbents. Two representative silicoaluminophosphates, SAPO-CHA (also called SAPO-34) and SAPO-AFI (also called SAPO-5), were synthesized in a tubular reactor within 10 and 5 min, respectively. The addition of a milled seed with small crystal size, the pretreatment of Al and Si sources by mechanical milling, and the employment of a high temperature condition were found to be the critical factors that contributed to the enhancement of crystallization rate of SAPO-CHA. The fast-synthesized SAPO-CHA possesses only isolated Si(OAl)₄ species, indicating a great potential in catalytic applications. SAPO-CHA and SAPO-AFI usually appear as a pair of competing phases during the synthesis of SAPO-CHA/SAPO-AFI because of similarities in chemical compositions and formation conditions. Here, we show that, owing to the feature of rapid heating, the tubular reactor demonstrated itself as a facile and precise platform to control over the phase selection between SAPO-CHA and SAPO-AFI by tuning the crystallization kinetics, which could not be realized in the conventional autoclaves. A continuous flow process was also established to synthesize these two silicoaluminophosphates with high efficiency and flexibility. These results demonstrate a comprehensive strategy to achieve the minute-order synthesis of two important silicoaluminophosphates and could be very useful to direct the ultrafast synthesis of other crystalline materials.