The catalytic activities and properties of platinum supported on siliceous MCM-41 and Al-modified MCM-41, such as Al-incorporated MCM-41 (AIMCM-41) and alumina-modified MCM-41 (Al2O3-MCM-41), for the hydrodesulfurization (HDS) of thiophene were investigated. A1203MCM-41 was prepared by an impregnation method using aluminum nitrate (AI(NO3)(3)center dot 9H2O) aqueous solution. Pt/Al2O3-MCM-41 catalyst showed high and stable activity for HDS of thiophene and this activity was remarkably higher than that of a commercial CoMo/Al2O3 HDS catalyst. The catalysts were characterized by XRD, hydrogen adsorption, ammonia-TPD, 2-propanol dehydration, cumene cracking and FT-IR. Dispersion of platinum on Al2O3-MCM-41 was remarkably higher than on MCM-41 or on AIMCM-41. It was revealed that the acidity of Al-2 O3MCM-41 was higher than that of MCM-41 or of AIMCM-41. Furthermore, it was observed that there exist Bronsted acid sites on Al-modified MCM-41. FT-IR spectra of thiophene adsorbed on Al-modified MCM-41 support indicates that thiophene molecules interact with Bronsted acid sites on Al-modified MCM-41. It was found that the HDS activity of Pt/quartz mixed mechanically with Al-modified MCM-41 catalyst was higher than that calculated. This suggests that there exists spillover hydrogen on supported Pt catalysts in the HDS of thiophene. Results revealed that the high activity of Pt/Al2O3-MCM-41 catalyst for HDS reaction is due to good harmony of high dispersion of Pt particles and Bronsted acidity of the support. (c) 2006 Elsevier B.V. All rights reserved.