Adsorption Property of Water Vapor on AlPO<sub>4</sub>-5 Synthesized from Aluminum Dross

Abstract

The aluminophosphate type zeolitic material, AlPO4-5 was synthesized by hydrothermal method using aluminum dross as a raw material, and its water vapor adsorption property was studied. Porous AlPO4-5 and nonporous AlPO4 were formed, and the selectivity of their formation was determined by varying the reactant ratios. Both AlPO4-5 and tridymite type AlPO4 (nonporous phosphate) were obtained from aluminum dross when the reaction products were synthesized with the following composition, Al2O3 : P2O5 : triethylamine (TEA) : H2O = 1 : 1 : 1 : 40. While AlPO4-5 was preferentially synthesized as a main product when the compositions were Al2O3 : P2O5 : TEA :H2O = 2 : 1 : 1 : 40 and 1 : 1 : 2 : 40. The variation in the reactant ratio dictated the specific surface area of the resulting reaction products. The formation of AlPO4-5 with a composition of 1 : 1 : 2 : 40 generated surface area of 353m2/g. The reaction products synthesized at 2 : 1 : 1 : 40 and 1 : 1 : 1 : 40 generated surface areas of 187 and 75m2/g, respectively. All the aluminophosphate products exhibited the type IVor V isotherm by IUPAC classification for water vapor adsorption due to the AlPO4-5 pore with strong affinity. This study demonstrated the efficacy of AlPO4-5 obtained from aluminum dross as desiccant, that is, the aluminum dross-derived AlPO4-5 demonstrated high adsorption capacity and adsorption properties suitable as an adsorbent or a desiccant. [doi:10.2320/matertrans.M-M2013831]