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Aluminum polyphosphate was prepared from aluminum nitrate solution and sodium polyphosphate solution with cation exchange resin in the molar ratio of Al/P = 1/3. Urea and hexamethylenetetramine were added in this preparation process. The thermal behavior of the obtained phosphates was analyzed by differential thermal analyses, X‐ray diffraction, and Fourier transform infrared spectroscopy. Furthermore, these materials and their thermal products were estimated by specific surface area, pore size distribution, particle size distribution, acid strength, amount of acidic sites, and adsorption of trimethylamine.

Aluminum phosphate is useful catalyst for many reactions. There are a lot of reports about catalytic activities of aluminum phosphate, however little reports about the relationship among the preparation, composition, catalytic activity of this phosphate. Phosphates transform to various other phosphates with hydrolysis and dehydration reactions by heating. In this work, some aluminum orthophosphates and condensed phosphates were prepared, and their compositions were estimated. Furthermore, specific surface area, acid strength, the amount of acidic sites, and the catalytic activities for the decomposition of trifluoromethane of these salts were investigated. Aluminum ortho‐ and polyphosphates were prepared in the systems of ortho‐ and poly‐phosphates. The catalytic activity for decomposition of CHF3 was related with a certain degree of specific surface area, acid strength, and the amount of acidic sites. Aluminum orthophosphate with a small amount of sodium cation had higher catalytic activity at lower temperature.