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Synthesis of aluminophosphate xerogels by non-hydrolytic sol-gel condensation of EtAlCl2 with trialkylphosphates



Druh Článek v odborném periodiku
Časopis / Zdroj Journal of Sol-Gel Science and Technology
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Klíčová slova Mesoporous xerogels; Aluminium phosphate; Non-hydrolytic synthesis; Sol-gel processing; Alkylhalide elimination mechanism
Popis We have investigated the preparation of high-surface-area mesoporous aluminophosphates by non-hydrolytic sol-gel method based on reactions of EtAlCl2 with trialkylesters of phosphoric acid (OP(OR)(3), R=Me, Et, Pr-i, Bu-n, in dry organic solvents. The condensations proceed by alkylchloride elimination. Various reaction and calcination conditions were examined. Porosity is obtained after calcination by removal of organic residual groups. This thermal processing at 300 degrees C of as-synthesized precursor gels leads to amorphous aluminophosphate xerogels with surface areas of 400-500m(2)g(-1) provided by small mesopores (2-8nm). Changes in the coordination environment of aluminium from six- to four-coordinate are evidenced by shift of Al-27 MAS NMR resonances. Highlights Dichloroethylalane reacts with trialkylphosphates by alkylchloride elimination.Aluminophosphate gels are obtained from the non-hydrolytic sol-gel technique.Thermal processing at 300 degrees C leads to amorphous xerogels with surface areas of 400-500m(2)g(-1).Porosity is composed of small mesopores (2-8nm).Templating with Pluronic P123 significantly improves pore size distribution.
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