BENZYLTRIMETHYLAMMONIUM CHLORIDE IMMERSION EFFECT ON PHYSICAL PROPERTIES OF TiO2 – Al203

Abstract

BENZYLTRIMETHYLAMMONIUM CHLORIDE IMMERSION EFFECT ON PHYSICAL PROPERTIES OF TiO₂ – Al₂O₃. Mesoporous TiO₂ - Al₂O₃ powders have potential applications in catalysts or support catalysts. A novel method to control pore size of sol--gel by a cationic surfactant benzyltrimethylammonium chloride (BTAC) Immersion was investigated. The gels of TiO₂- Al₂O₃ in molar ratio of 0.2 of TiO₂, and 0.8 of Al₂O₃ were prepared by hydrolysis of aluminium sec-butoxide, Al(OC₄H₉^sec)₃ and titanium isopropoxide Ti(OC₃H₇^iso)₄ in an n-propanol solution with acid catalyst. The structures and porosities of the modified TiO₂-A|₂O₃ was depended on the dimensions of surfactant, as long as the calcination was carried out at 500℃ to avoid aggregation process during removal of excess BTAC. If the calcinations were carried out at 800℃ no significant change of the pore volume of modified samples was remarkably not observed, even though formation of TiO₂ rutile has been taken place. It indicated that samples modification by initial immersion of gel into BTAC may avoid the sintering. These results suggest that during the calcinations TiO₂, was segregated from the Al₂O₃ particles to form nuclei of rutile and was crystallized prior to formation of α- Al₂O₃. Therefore, the formation of rutile TiO₂ induced the formation of α- Al₂O₃.