Synthesis And Characterization Of Microporous Aluminophosphaste AlPO-CJ2 With The Framework

The contents of this thesis include two parts. No. 1: microporous aluminophosphaste AlPO-CJ2 with the framework containing heteratomic Eu: synthesis and characterization. No.2, the study of structure and properties of microporous aluminophosphaste AlPO-21 prepared by co-template method.Zeolite molecular sieves (MS) were prepared artificially in the 1940's. A numerous research works based on the structural analysis indicate that zeolite is a type of materials possessing ordered channel system. The framework of zeolite consists of SiO4 and AlO4 tetrahedron. In the 1980's, a great progress was made, which is a landmark in the field of zeolite MS. That is the discovery of the aluminophosphate MS. The framework of this kind of materials is composed of AlO4, PO4 tetrahedra. Since the discovery of the new AlPO-n molecular sieves (MS) family by Flanigen and co-workers in 1982, the traditional idea that zeolite molecular sieves can be merely constructed with tetrahedron of AlO4 and SiO4 are changed completely. From then on, numerous phosphates MS, which possesses various novel framework topography or the analogue structure of known zeolite were synthesized for the potential applications not only on adsorption, separation and catalysis, but also on composite functional materials.The coordination of Al atom and the linkage style of polyhedron in the framework are essential for influence on the structural and surface property as well as the stability of the MS. Usually, Al atom coordinates with four oxygen atoms and forms AlO4 tetrahedron. In some micro-porous structures of alumino-phosphate (containing layered and 3-D structure), Al atoms exhibit the ability to take five- and six-fold coordination and form AlO5 trigonal bipyramid and AlO6 octahedron, respectively.In the process of preparation of AlPO, an important discovery is aluminophosphate with Al atoms whose coordination number is more than 4. It reminds us, not only tertrahedra is the basic unit of MS, but also octahedral and trigonal bipyramide can construct the framework of MS as well. The microporous aluminophosphate AlPO-CJ2 was prepared firstly using hexamethylenetetra-amine as a template by L. Yu et al in 1990. The framework structure, as authors described, consists of AlO5, AlO5F and PO4 units. Noticeably, the six-fold coordinated Al atom is coordinated by five framework oxygen atoms, and bonded to one F atom in an asymmetric unit as well. In this thesis, we synthesized the AlPO-CJ2 in the reactant system of Al2O3-P2O5-NH4F-H2O andAl2O3-P2O5-CO(NH2)2-NH4F-H2O and proved that the true template is NH4+ cation.It is worthwhile to incorporate europium into the framework of AlPO-CJ2 analogue to obtain a new phosphor. Because not all oxygen atoms are shared in the framework of AlPO-CJ2, terminal oxygen atoms appear in the AlO6 groups. This terminal oxygen atom is possible to absorb the energy with charge transfer process, which would enhance the luminescence of phosphor. Based on the novel structural properties of AlPO-CJ2, we prepared the AlPO-CJ2 containing heteroatomic Eu for a new type of phosphor. The results of characterization with XRD, ICP, Mossbauer, Mas NMR and fluorescent spectra show that Eu has been incorporated into the framework of AlPO-CJ2 and substitute the site of Al(V). Meanwhile the excitation spectrum indicates that there is a charge transfer process in the framework. The another part of the thesis is that the study of AlPO-21, an aluminophosphate containing Al(IV) and Al(V) in the framework. AlPO-21 was synthesized firstly in 1982 and the structure was resolved in 1985. The framework of AlPO-21 is compose of AlO4, AlO5 and PO4 polyhedra. There are some interesting features on the AlPO-21 structure. Generally, Al- and P-containing polyhedra are linked in a strictly alternating manner, which is known as Lowenstein rule. Naturally, it benefits to dispersing the charge furthest to ob...