Influence of the activation atmosphere on the hydrodesulfurization of Co-Mo/SBA-15 catalysts prepared from sulfur-containing precursors
Résumé
Mesoporous SBA-15 material was used as support of binary Co-Mo hydrodesulfurization (HDS) catalysts prepared using a novel approach based on the use of already sulfided precursors (ammonium tetrathiomolybdate and cobalt diethyldithiocarbamate). The effects of atmosphere and activation temperature were studied to optimize the preparation of highly active CoMo/SBA-15 hydrodesulfurization catalysts. Two sets of catalysts were synthesized using either a N-2/H-2 (10% H-2) or a H-2/H2S (15% H2S) atmosphere at three different temperatures of activation (723, 773 and 823 K). The catalysts were tested in the HDS of dibenzothiophene (DBT) and the catalysts were characterized by N-2 physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The use of already sulfided precursors leads to a homogeneous dispersion of the active phase inside the SBA-15 channels. Moreover, the N-2/H-2 activation procedure at 723 K allows obtaining optimized HDS active catalysts. Finally, a confinement effect of MoS2 slabs inside the SBA-15 channels leads to a high selectivity along the direct desulfurization pathway. (C) 2012 Elsevier B.V. All rights reserved.