title: Ionothermal Synthesis of MnAPO-SOD Molecular Sieve without the Aid of Organic Structure-Directing Agents.
abstract: 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.
authors.affiliation: University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Tian
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Yasong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
authors.forename: Huaijun
authors.initials: H
authors.lastname: Ma
authors.forename: Renshun
authors.initials: R
authors.lastname: Xu
mesh_terms: D018360:Crystallography, X-Ray; D008855:Microscopy, Electron, Scanning; D009930:Organic Chemicals / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009930:Organic Chemicals