Abstract: A new mesosilica-encapsulated Keggin type heteropolyacid-HPW/SiO₂ was synthesized by adding HPW into a sol-gel system to form mesoporous silica involving hydrolysis of tetraethyl orthosilicate under the strong acidic synthesis conditions(pH<0). The mesosilica-impregnated heteropolyacid thus synthesized are insoluble and readily separable mesoporous composite materials with uniform mesopores and high specific surface areas. Their structures and physical-chemical properties was characterized by various methods, their catalytic activity were measured by the cracking of cumene and 1,3,5-triisopropylbenzene, and esterification reactions of acetic acid with ethanol and benzoic acid with t-butanol. The results show that the HPW is tightly encapsulated into the network of mesosilica walls and does not leach from the walls of mesosilica. The HPW/SiO₂ composite materials are the promising and new catalysts for acid-catalytic reactions, and the potential replacer of the homogenous reaction catalysts to solve the separation and recycle problems.

Key words: SBA-15, Tungstophosphoric acid, Encapsulation, Composite material, Bulky molecular catalysis