Jointly published by React.Kinet.Catal.Lett. Akadémiai Kiadó, Budapest Vol. 79, No. 1, 35-42 and Kluwer Academic Publishers, Dordrecht (2003) 0133-1736/2003/US$ 20.00. © Akadémiai Kiadó, Budapest. All rights reserved. RKCL4147 MOLYBDENUM HDS CATALYSTS SUPPORTED ON NIOBIA-SILICA Sonia Damyanova a *, Stanislava Andonova a , Iskra Stereva a , Chavdar Vladov a , Lachezar Petrov a and Paul Grange b a Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria, e-mail: soniad@satline.net b Université Catholique de Louvain, Unité de Catalyse et Chimie de Matériaux Divisés, Place Croix du Sud, 2/17, 1348 Louvain-la-Neuve, Belgium Received June 14, 2002 In revised form October 11, 2002 Accepted October 30, 2002 Abstract The effect of the amount of Nb 2 O 5 on the dispersion and reductive properties of Mo/Nb 2 O 5 -SiO 2 catalysts has been studied. Addition of niobium leads to an increase of dispersion and the reducibility of molybdenum. A synergetic effect of niobium on the catalytic activity in hydrodesulfurization of thiophene was observed at 5.4 wt.% of Nb 2 O 5 . Keywords: Niobia, molybdenum catalysts, hydrodesulfurization INTRODUCTION The present environmental problems open up a challenge for the development of new hydrotreating catalysts, capable of decreasing the content of heteroatoms in different oil cuts. The bifunctional catalysts for hydrodesulfurization (HDS) are based on supported metal sulfides (MoS 2 or WS 2 ) and promoters (Co or Ni). The most commonly used support for these catalysts is alumina [1,2], titania [3] or mixed oxides [4,5]. It is well known that silica-supported molybdenum catalysts give lower HDS activity due to the agglomeration of molybdenum species on the surface of silica caused by the inertness of the support. Higher hydrotreating performances for these catalysts can be achieved by changing the support composition, by addition of other oxides that will lead to a modification of the textural properties as well as the acid-base character of the support.