Alumina supported HDS catalysts prepared by impregnation with new heteropolycompounds. Comparison with catalysts prepared by conventional Co-Mo-P coimpregnation

Hydrodesulfurization (HDS) catalysts prepared by the incipient wetness impregnation method with Co-Mo-P based solutions were characterized with various physical techniques and their efficiencies in HDS of thiophene were evaluated. Depending on the Co-Mo-P precursors used to prepare the impregnating solution, different heteropolyanions (HPAs) were characterized. In conventional solutions, P2Mo5O236- or P2Mo18O626- type entities were evidenced. Preparations with Keggin type HPAs were also studied (PMo12O403-) and an original method of preparation which allows the deposition of alumina on reduced Keggin type HPAs (PMo12O407-) is described. If the non-reduced HPAs (whatever their structure) are decomposed on alumina, the reduced ones could be partially preserved even after calcination, leading to the synthesis of more efficient catalysts. (C) 1998 Elsevier Science B.V. All rights reserved.