Aluminophosphates anionic framework

Since the discovery of neutral framework aluminophosphate molecular sieves AlP04-n, a large number of anionic framework aluminophosphates have been reported. Jilin group has carried out systematic research in this field.1144-1471 Recently, they have built up a... 

So far, a large number of nondense aluminophosphates have been successfully synthesized via the solvothermal synthesis system. Most of them have anionic frameworks except for those crystallized from hydrothermal synthesis systems, such as AlP04-5, A1P04-11, and A1P04-21. The stoichiometries of these aluminophosphates include... 

Similarly, as shown in Figure 3.21 (b), (c), (d), and (e), there exists an excellent linear correlation between the charge/volume of the charged species encapsulated in the framework and the charge density of the anionic framework for the anionic aluminophosphates with Al/P ratio of 1/2 directed by arylamines, the anionic aluminophosphates with Al/P ratio of 2/3 directed by cyclic amines, the layered anionic aluminophosphates with Al/P ratio of 3/4 and 4,6,8-net topological sheet structure directed by chain-shape alkylamines, and the layered anionic aluminophosphates with Al/P ratio of 3/4 and 4,6,12-net topological sheet structure directed by chain-shape alkylamines as well. 

W.F. Yan, Syntheses, Structures, and Design of Aluminophosphates with Anionic Frameworks. PhD Thesis, Jilin University, China (2002). 

CH2)6N/iH3 H20 i 1041 built up from the strict alternation of A10 /A106 and PO4 units, aluminophosphate APO-HDA with intersecting 12-ring and 18-ring channels, and numerous other 3-D anionic framework and 2-D layer structures. The Al/P ratios of these compounds include 1/1, 1/2, 2/3, 3/4, 4/5, 5/6, 11/12, 12/13, 13/18, etc. This greatly enriches the open-framework aluminophosphate family, showing their structural and compositional diversity.1641... 

Additional elements or functional groups may be incorporated into the anionic framework of the VOPO class in order to increase framework stability or to provide additional stmctural flexibility. The presence of aluminum in the framework, for example, results in enhanced thermal stability of the phases. Borate serves not only as a framework constituent but as an effective solubilizer of the metal oxide components. Addition of fluoride to silicates and aluminophosphates and gaUophosphates (188-191) results in enhanced mineralization and induces crystallization in neutral and acidic pH. While VOPO phases incorporating such additional constituents are relatively unexplored, the few... 

It follows that through its chemical composition and geometry the zeolite host exerts a considerable influence over the structure and stability of ionic clusters in zeolites and does not act merely as a convenient inert host. In particular, the formation of ionic clusters is much more likely to occur in aluminosilicates with a high aluminium content and a sizable anionic framework charge than in neutral aluminophosphate molecular sieves. In fact, a significant proportion of zeolite ionic clusters are found in just three aluminosilicate frameworks, each of which contains the sodalite cage structural unit (Fig. 1). 

Huoride may adopt a number of roles in the hydrothermal synthesis of phosphate-based materials. In addition to its mineralizing effect, fluoride may have a catalytic role, as manifested in the synthesis of AIPO4-I4A, which requires fluoride, although it is not incorporated into the framework (213). However, the most extensive use of fluoride has been in the synthesis of new aluminophosphate and gallophosphate architectures that directly incorporate the fluoride into the framework (214, 215). While fluoride incorporation into vanadium phosphate structures remains relatively unexplored, the phases studied to date reveal profound structural influences concomitant to incorporation of fluoride into the anionic scaffolding. 

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