Ionothermal Synthesis of MnAPO-SOD Molecular Sieve without the Aid of Organic Structure-Directing Agents

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• 作者：Hao Liu ; Zhijian Tian ; Lei Wang ; Yasong Wang ; Dawei Li ; Huaijun Ma ; Renshun Xu
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1809-1815
• 全文大小：343K
• ISSN：1520-510X

文摘

An SOD-type metalloaluminophosphate molecular sieve (denoted as SOD-Mn) was ionothermally synthesized by introducing manganese(II) cations into the reaction mixture via MnO–acid or MnO₂–reductant reactions. Composition and structure analyses results show that two kinds of manganese(II) cations exist in the SOD-Mn structure. Part of the manganese(II) cations isomorphously substitute the framework aluminum(III) with a substitution degree of ∼30%. The rest of the manganese(II) cations occupy a fraction of the sod cages in their hydrated forms. A comprehensive investigation of the synthesis parameters, crystal sizes, and crystallization kinetics indicates that the in situ released hydrated manganese(II) cations direct the formation of SOD-Mn. Such structure-directing effect may be inhibited by both the fluorination of manganese(II) cations and the water accumulation during crystallization. In the fluoride anion-containing reaction mixture with a low ionic liquid content, the crystallization process is strongly suppressed, and large SOD-Mn single crystals of over 200 μm in size are yielded. SOD-Mn is free from organics and shows improved thermal stability compared with metalloaluminophosphates synthesized by using organic structure-directing agents.