Gallophosphates synthesis

Two ammonium templated gallophosphates Synthesis and structure determination from powder diffraction data of 2D and 3D-GAPON". Micro. Meso. Materials, 2002, 53, 87. 

In 1982, Union Carbide reported the synthesis of the first phosphate-based molecular sieves (95, 96). This finding would include aluminophosphates (A1P04) and gallophosphates (GaP04) as well as silicoaluminum phosphates (SAPO) and metalloaluminum phosphates [MAPO, M = first-row transition metal (TM)]. The... 

In 19851 a gallophosphate with a porous framework structure was reported by Parise (ref. 4). This was followed by the systematic synthesis of the GaPO family (refs. 5,6) in our laboratory and the structural characterization of several single crystals of the compounds (refs. 7 11). 

Recently, we also focused attention on the synthesis of aluminoarsenates and galloarsenates with open framework structures (refs. 12—14). While the aluminophosphates are labeled as AlPO s, the gallophosphates, aluminoarsenates and galloarsenates can be designated as AlPO s, AlAsO s and GaAsO s respectively. 

The alumino and gallophosphates were formed [7] in the systems amine-Al(Ga)203—P205—H20 using the same way of the synthesis and the same range of temperatures and pressure. However, the introduction of phosphoric acid in the synthesis lowered the pH of the solutions to a neutral or weakly acidic medium which favours higher coordinations for aluminium and gallium ions. The combined effect of pH and of the shape of the amines lead to ca two hundred structure types. 

T. Loiseau and G. Ferey, Oxyfluorinated Microporous Compounds, VII. Synthesis and Crystal Structure of ULM-5, a New Fluorinated Gallophosphate Ga1g(P04)14 (HP04)2 (OH)2F7 [ I I3N(CI I2)6NI I3 4 6I I20 with 16-Membered Rings and both Bonding and Encapsulated F. J. Solid State Chem., 1994, 111, 403 415. 

Q. Huo and R. Xu, Synthesis of the Gallophosphate Molecular Sieve Cloverite with 20-ring Channel from an Alcoholic System. J. Chem. Soc., Chem. Commun., 1992, 1391-1392. 

F was used for the first time as mineralizer in the synthesis of zeolites under neutral or acidic conditions by Flanigen and Patton1941 Subsequently, Guth and Kessler further studied this new synthetic method.[95] Many high- or all-silica zeolites such as ZSM-5, ZSM-23, Theta-1, ferrierite, / , MTN, AST, UTD-1, ITQ-3, ITQ-4, and heteroatom (B, Al, Fe, Ga, and Ti)-substituted high-silica zeolites could be synthesized from an F synthetic system. In addition, most of the open-framework gallophosphates could be hydrothermally synthesized under the influence of F. ... 

After a brief review on the templating role of F in the synthesis of molecular sieves, this study focuses on the transformation of Mu-3 into Mu-2, two fluorinated gallophosphates with ID and 3D arrangement of fluorinated D4R units respectively. Depending on the water content and on the temperature, Mu-2 or another gallophosphate free of D4R units crystallizes. The transformation is studied by XRD analysis and NMR spectroscopy. The different results obtained show clearly that this transformation does not occur via a complete dissolution. Based on the F NMR spectra, the presence of a fluorinated D4R unit, in the solution, cannot be excluded. 

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. 

In the last two decades there has been considerable progress in the synthesis of molecular sieve materials. One result of these efforts is cloverite, a large-pore gallophosphate molecular sieve with a 20 T-atom cloverleaf-shaped entrance into a supercage of about 30 A diameter, which has attracted attention not only due to potential novel adsorption and catalytic properties and the uptake of bulky adsorbates, but also as a host for the preparation of semiconductor nanoclusters, as an example for the development of new advanced materials. 

Merrouche, A., Patarin, J., Soulard, M., Kessler, H. and Anglerot, D. (1991) "Orienting effect of fluoride anions in the synthesis of a new gallophosphate of the LTA type" in M.L. Occelli and H. Robson (eds). Advances in Zeolites and Pillared clays Synthesis, Van Nostrand (submitted). 

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