Boddenberg Bruno, Radha Rani V, Grosse Reiner
University of Dortmund, Department of Chemistry, Physical Chemistry II, Otto-Hahn Strasse 6, D-44227 Dortmund, Germany.
Langmuir. 2004 Dec 7;20(25):10962-9. doi: 10.1021/la048413r.
SAPO-5 molecular sieve was synthesized according to patent literature and characterized with X-ray diffraction, electron microscopy (SEM, TEM), and solid state magic angle spinning NMR spectroscopy. The material of particles in the micrometer region was found to consist of ca. 20 nm microcrystallites packed in mostly parallel orientation to ca. 200 nm sized agglomerates. The nitrogen adsorption isotherm was measured at 77.6 K over ca. 7 decades of pressure up to pore saturation. The course of the isotherm is interpreted to consist of filling of the nanopores (diameter, 0.73 nm) up to 2N(2)/unit cell, subsequent multilayer adsorption on the outer surface of the agglomerates, and, finally, pore condensation in the interparticle adsorption space. The nanopore adsorption can be quantitatively reproduced with the statistical mechanical model of a quasi one-dimensional lattice gas taking intermolecular interactions into account. The evaluated energy parameters are of physically reasonable magnitude and agree with literature data. The multilayer part of the adsorption isotherm can be well represented by the Brunauer-Emmett-Teller model yielding a specific outer space area (63 m(2) g(-)(1)) which is consistent with estimated geometrical and pore size analysis data.
根据专利文献合成了SAPO - 5分子筛，并通过X射线衍射、电子显微镜（扫描电子显微镜、透射电子显微镜）和固态魔角旋转核磁共振光谱对其进行了表征。发现微米级区域的颗粒材料由约20纳米的微晶组成，这些微晶大多以平行取向堆积成约200纳米大小的团聚体。在77.6 K下，在约7个数量级的压力范围内直至孔饱和，测量了氮气吸附等温线。等温线的过程被解释为纳米孔（直径0.73纳米）填充至每个晶胞2个N₂，随后在团聚体的外表面进行多层吸附，最后在颗粒间吸附空间发生孔凝聚。考虑分子间相互作用的准一维晶格气体统计力学模型可以定量再现纳米孔吸附。评估的能量参数具有合理的物理量级，并且与文献数据一致。吸附等温线的多层部分可以很好地用布鲁诺尔 - 埃米特 - 特勒模型表示，得到的比外表面积为（63 m² g⁻¹），这与估计的几何和孔径分析数据一致。
