Characterization and evaluation of ZrO2 supported hydrotreating catalysts

A series of zirconia supported molybdenum catalysts were prepared and characterized by BETSA, XRD, TPR, FTIR, XPS and oxygen chemisorption. Thiophene, cyclohexene and tetrahydrofuran were taken as model compounds for evaluating their hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodeoxygenation (HDO) activities, respectively. The XRD results indicate that Mo is present as a monolayer up to 6 wt.%; loading, whereas MoO3 crystalline growth is observed beyond this loading. O-2-uptalie and catalytic activities also increase up to 6 wt.% Mo-loading but above this loading both start decreasing. There are good correlations between O-2 uptake and all catalytic activities. TPR and FTIR results indicate that at lower loading, MoO3 is present as tetrahedra form and at moderate loading, both tetrahedral and octahedral forms are found. XPS results reveal that the electron transfer is taking place from support to molybdenum. (C) 2000 Elsevier Science B.V. All rights reserved.