Synthesis and characterization of hydrotreating Mo catalysts supported on titania-modified MCM-41

A series of Ti modified MCM-41 supports and their respective Mo catalysts were prepared and characterized to study the effect of support preparation method on the dispersion of titania and on the characteristics of Mo surface species. Two methods of post-synthetic incorporation of titania were tested: chemical grafting and incipient wetness impregnation. The characterization results were compared to those obtained with Ti-MCM-41 supports where Ti was incorporated during the hydrothermal synthesis of MCM-41 (synthetic route). The results show that supports with different TiO2 content and dispersion, can be obtained. The synthetic route allows to prepare mesoporous supports with ordered structure and high surface area only if the titania content is low (less than 10 wt.%). On the contrary, the postsynthetic methods allow to achieve higher titania loadings without substantial loss of MCM-41 characteristics. The best dispersion of TiO2 in the MCM-41 channels was obtained by the grafting method. Clear differences in the characteristics of Mo species were observed (Raman and XRD) for catalysts supported on Si-MCM-41, Ti-MCM-41 and Si-MCM-41 covered with titania. The latter materials, prepared via post-synthetic route, show promising features as supports for Mo based hydrotreating catalysts. (C) 2001 Elsevier Science B.V. All rights reserved.