Removal of polynuclear aromatics from diesel fuel has become a focus of intense research due to the stringent environmental legislation associated with clean fuels. In this work, selective ring opening of model compound decalin over the set of catalysts comprising of 1) Ir-Pt supported on mesoporous Zr-MCM-41, large and medium pore zeolites like HY and H-Beta and 2) Ni-Mo/carbide on HY, H-Beta, Al-SBA-15, ¥ã- alumina and silica alumina were studied. All the catalysts were extensively characterized by BET surface area measurement, CO-chemisorption, XRD, FTIR, TPR and TPD of ammonia. Ring opening of decalin was studied on these catalysts in a trickle-bed reactor in a temperature range of 200- 400 ¡ÆC, pressure range of 2-7 MPa and LHSV of 1 to 3 h- 1. 31.7 and 65.0 wt.% of RO yield and selectivity were observed on Ir-Pt/HY catalyst at 220 ¡ÆC, whereas 34.0 and 40.0 wt.% of ring opening yield and selectivity were observed on Ni-Mo carbide/HY catalyst at 240 ¡ÆC. From the model compound studies, Ir-Pt/HY, Ni-Mo carbide/HY and Ni-Mo carbide/H-Beta were selected for study of hydrotreated light gas oil in a trickle bed reactor. Ni-Mo carbide/HY performed better over other catalysts and increased the cetane index of hydrotreated light gas oil by 12 units at 325 ¡ÆC. A first order kinetic model was fitted for the hydrotreated light gas oil study. 89, 111 and 42 KJ/gmol of activation energies was observed for dearomatization, aromatization and naphthenes cracking steps, respectively. The thermodynamic equilibrium calculations reveal that the selectivity of ring opening products of decalin can be maximized by favoring the formation of unsaturated compounds at higher operating temperatures. Energetics of dealkylation and ring opening reactions of naphthenes in gas phase and on the surface of Br©ªnsted acid sites were calculated using quantum chemical simulations. In iv gas phase, ratio of Arrhenius activation energies for forward and reverse reactions of RO and dealkylation reactions are 1.92 and 1.82 respectively. Deakylation on different level clusters revealed that surface reaction is the rate controlling.

Removal of polynuclear aromatics from diesel fuel has become a focus of intense research due to the stringent environmental legislation associated with clean fuels. In this work, selective ring opening of model compound decalin over the set of catalysts comprising of 1) Ir-Pt supported on mesoporous Zr-MCM-41, large and medium pore zeolites like HY and H-Beta and 2) Ni-Mo/carbide on HY, H-Beta, Al-SBA-15, ¥ã- alumina and silica alumina were studied. All the catalysts were extensively characterized by BET surface area measurement, CO-chemisorption, XRD, FTIR, TPR and TPD of ammonia. Ring opening of decalin was studied on these catalysts in a trickle-bed reactor in a temperature range of 200- 400 ¡ÆC, pressure range of 2-7 MPa and LHSV of 1 to 3 h- 1. 31.7 and 65.0 wt.% of RO yield and selectivity were observed on Ir-Pt/HY catalyst at 220 ¡ÆC, whereas 34.0 and 40.0 wt.% of ring opening yield and selectivity were observed on Ni-Mo carbide/HY catalyst at 240 ¡ÆC. From the model compound studies, Ir-Pt/HY, Ni-Mo carbide/HY and Ni-Mo carbide/H-Beta were selected for study of hydrotreated light gas oil in a trickle bed reactor. Ni-Mo carbide/HY performed better over other catalysts and increased the cetane index of hydrotreated light gas oil by 12 units at 325 ¡ÆC. A first order kinetic model was fitted for the hydrotreated light gas oil study. 89, 111 and 42 KJ/gmol of activation energies was observed for dearomatization, aromatization and naphthenes cracking steps, respectively. The thermodynamic equilibrium calculations reveal that the selectivity of ring opening products of decalin can be maximized by favoring the formation of unsaturated compounds at higher operating temperatures. Energetics of dealkylation and ring opening reactions of naphthenes in gas phase and on the surface of Br©ªnsted acid sites were calculated using quantum chemical simulations. In iv gas phase, ratio of Arrhenius activation energies for forward and reverse reactions of RO and dealkylation reactions are 1.92 and 1.82 respectively. Deakylation on different level clusters revealed that surface reaction is the rate controlling.

L'ouverture sélective de cycle (OSC) d'hydrocarbures polycycliques vise à augmenter le nombre de cétane des carburants diesel. OSC efficace peut être atteint par l'hydroconversion sur des catalyseurs bifonctionnels métal noble/fonction acide. La décaline et, à plus faible mesure, le perhydroindane, le butylcyclohexane et la tétraline, ont été utilisés comme molécules modèles pour l'étude des l'OSC de sulfures de métaux de transition (TMSs) supportés sur zéolithes ou silice-alumine amorphe dans un réacteur à lit fixe sous haute pression (5 MPa) avec une concentration élevée d'H2S dans la charge réactionnelle (1 %). Les nombreux produits d'hydroconversion ont été identifiés grâce à la chromatographie gazeuse bidimensionnelle, qui nous a permis de mieux comprendre les mécanismes de réaction. Ce travail a consisté à l'étude de la nature et la charge du SMT et la nature du support. Comparé à la zéolithe seule, le catalyseur RuSx/HY (qui sert de référence) est plus stable et dix fois plus actif avec une sélectivité en produits d'ouverture proche des 30% à 240 °C. Les produits les plus abondants restent les produits d'isomérisation, ce qui suggère que l'acidité du support domine le schéma réactionnel. Quant à l'ajout de TMS, leur rôle est d'activer l'hydrogène, de favoriser les réactions d'hydrogénation/déshydrogénation et limiter le cokage des sites acides. NiSx/HY est aussi performant que les catalyseurs à base de Ru, Ir ou Rh et un effet de synergie est observé pour les catalyseurs ternaires Ni-Ru et Ni-Rh. Toutefois, comparé aux métaux nobles comme l'Ir et le Ru étudiés sans H2S, les catalyseurs sulfures sont quasiment non-hydrogénolysants. Enfin, la zéolithe HY présente des performances proches a la H-Beta mais avec moins de craquage / The selective ring opening (SRO) of polycyclic hydrocarbons aims at increasing the cetane numbers of diesel fuels. Efficient SRO can be achieved through hydroconversion over bifunctional noble metal/acid catalysts. Decalin and, to lower extents, perhydroindan, butylcyclohexane and tetralin, have been used as model molecules to investigate the SRO performances of transition metal sulfides (TMSs) supported on zeolites or amorphous silica-alumina in a high-pressure (5 MPa) flow-fixed bed reactor with a high concentration of H2S in the reactant feed (1 %). The numerous hydroconversion products have been identified using comprehensive two-dimensional chromatography for various levels of reactant conversions, which allowed us to gain insight into the reaction mechanisms. The presence, loading and nature of the TMS, and the nature of the support, have been investigated. With respect to the bare HY zeolite, RuSx/HY (which served as our reference) is more stable and ten times more active, with a ring-opening selectivity of up to 30 % at 240 °C. The most abundant products are skeletal-isomerization ones, which suggests that the acidic support dominates the reaction scheme. The TMS role is to activate hydrogen, catalyze hydrogenation/ dehydrogenation and prevent the coking of acidic sites. NiSx/HY performs similarly to Ru, Ir and Rh-based catalysts, and a synergetic promoting effect is observed for Ni-Ru and Ni-Rh combinations. However, with respect to noble metals such as Ir and Ru under H2S-free conditions, the sulfide counterparts appear much less (if not) hydrogenolytic. As compared to HY, the H-Beta support shows similar performance but promotes cracking