Synthesis and characterization of a fluorinated anionic aluminophosphate framework UT-6, and its high-temperature dehydrofluorination to AlPO4-CHA
Synthesis and characterization of a fluorinated anionic aluminophosphate framework UT-6, and its high-temperature dehydrofluorination to AlPO4-CHA
复制标题
DOI：
10.1039/a606828f
复制
发表时间：
1997
影响因子：
--
通讯作者：
S. Oliver;A. Kuperman;A. Lough;G. Ozin
中科院分区：
文献类型：
--
作者：
S. Oliver;A. Kuperman;A. Lough;G. Ozin
用单晶X射线衍射和19 FMASNMR、31 PCPMASNMR和27 AlMQMASNMR测定了阴离子磷酸铝分子筛UT-6的结构。当使用痕量氟化氢时，在非水合成系统中生长大晶体。标题化合物[Al 3 P3 O 12 F] - [C5 H5 NH] + ·0.15H2O属于三斜晶系，空间群为P Z=2，a=9.118（1），B=9.161（1），c=9.335（1）A，α=85.98（1），β=77.45（1），γ=89.01（1）°，V=759.25（14）A3，R1 =0.0280，wR2 =0.0830。UT-6是一种小孔材料，具有贯穿结构的三维通道网络。其结构与菱沸石结构密切相关。除了通过桥接氧连接的交替四面体磷和铝原子之外，在UT-6骨架的四元环中也存在孤立的八面体铝对，其共享两个桥接氟原子。骨架上产生的负电荷由存在于菱沸石笼中的吡啶鎓阳离子平衡。UT-6经热处理后，吡啶分子和HF从结构中被去除，材料转变为菱面体AlPO 4 -CHA，原位高温粉末X-射线衍射、热重分析和质谱分析证明了这一点。这代表了阴离子铝磷酸盐分子筛骨架到完全中性骨架的第一次固态转变。
The structure of an anionic aluminophosphate molecular sieve UT-6 has been determined by single-crystal X-ray diffraction and 19 F MAS NMR, 31 P CP MAS NMR and 27 Al MQ MAS spectroscopy. Large crystals were grown in a non-aqueous synthesis system when hydrogen fluoride was used in trace amounts. The title compound, [Al 3 P 3 O 12 F] - [C 5 H 5 NH] + ·0.15H 2 O, crystallizes in the triclinic space group P (no. 2), with Z=2, a=9.118(1), b=9.161(1), c=9.335(1) A, α=85.98(1), β=77.45(1), γ=89.01(1)°, V=759.25(14) A 3 , R 1 =0.0280 and wR 2 =0.0830. UT-6 is a small pore material that has a three-dimensional network of channels running through the structure. The structure is closely related to that of chabazite. In addition to alternating tetrahedral phosphorus and aluminium atoms connected by bridging oxygens, there are also isolated pairs of octahedral aluminiums in the four-membered rings of the UT-6 framework that share two bridging fluorine atoms. The resulting negative charge on the framework is balanced by pyridinium cations that reside in the chabazite cages. Upon thermal treatment of UT-6, pyridine molecules and HF are removed from the structure and the material transforms into rhombohedral AlPO 4 -CHA, as evidenced by in situ high-temperature powder X-ray diffraction, thermogravimetry and mass spectrometry. This represents the first solid-state transformation of an anionic aluminophosphate molecular sieve framework to an entirely neutral one.