Abstract: Amphiphilic HZSM-5 zeolite particles were prepared by a partial modification of the external surface of HZSM-5 zeolite with trimethylchlorosilane. These amphiphilic zeolite particles were oriented at the water-organic boundary when they were added to the mixture of cyclohexene and water or water with CCl₄. IR spectra indicated that the intensity of the band for the terminal silanols decreased significantly and the band for the methyl groups(C_H stretching vibration) emerged after modification, which gave a direct evidence that partial hydrophilic silanol groups on the surface of the zeolite were replaced by the hydrophobic alkylsilyl groups. This amphiphilic HZSM-5 zeolite exhibited a much higher catalytic activity than the parent HZSM-5 zeolite in the hydration of cyclohexene phase-boundary reaction without adding co-solvents and stirring. Because this phase-boundary reaction was proceeding through a channel-reaction mechanism, the hydrophobic HZSM-5 particles modified by trimethylchlorosilane also showed the better catalytic performance than the parent zeolite.

Key words: Amphiphilic zeolite, Preparation, Characterization, HZSM-5, Phase-boundary catalysis