Evaluation of the location of Al atoms in zeolite by high resolution 27Al MAS and MQMAS NMR techniques.

硅酸铝分子筛的催化性能与孔结构、酸强度和酸量等诸多因素有关。此外，铝原子在沸石骨架中的位置被认为是影响活性和选择性的重要因素，因为它们会深刻地影响分子对酸性中心的可及性和孔内反应场的空间限制，但它们的控制和评价一直难以实现。考察了合成ZSM-5分子筛的有机结构导向剂(OSDAs)和钠离子对铝原子在骨架中的位置、酸性和催化性能的影响。我发展了一种用高分辨率27Al MAS和MQMAS核磁共振技术评估Al原子位置的方法。

The catalytic properties of aluminosilicate-type zeolites depend on many factors such as pore structure, acid strength and acid amounts. In addition these factors, the location of Al atoms in the zeolite framework has been recognized as an important factor for activity and selectivity, because they would profoundly affect the accessibility of molecules to acid sites and the spatial constraints of the reaction field in the pores; however, their control and evaluation have been difficult to achieve.In this study, In-situ FT-IR spectroscopy using CO as probe molecule was applied to the evaluation of acid property of the ZSM-5 zeolites. The effects of the organic structure-directing agents (OSDAs) and Na cation for the synthesis of ZSM-5 on the location of Al atom in the framework as well as acidic properties and catalytic properties were investigated. I have developed a method for evaluating the location of Al atoms by high resolution 27Al MAS and MQMAS NMR techniques.