A study on middle distillate hydrotreatment zeolite catalysts containing Pt/Pd and/or Ni was performed. The effect of the addition of the corresponding CoMo, CoMoPd, CoMoPtPd and CoMoNi in PdNiPt-zeolite, Pt-zeolite, Ni-zeolite, and PdPt-zeolite was studied. The catalysts were characterized physically and chemically by methods and techniques such as Brunauer-Emmett-Teller (BET), Barret-Joyner-Hallenda (BJH), and neutron activation analysis. The structures of the Ni and Pt containing zeolite were studied by X-ray Photoelectron Spectroscopy (XPS). An experimental apparatus was constructed to investigate the activity of the experimental catalysts. The catalysts activity measured in terms of conversion of dibenzothiophene (DBT), substituted dibenzothiophenes (sDBT) and phenanthrene as well as molar-averaged conversion was evaluated in a continuous flow Robinson Mahoney reactor with stationary basket in the hydrodesulfurization and hydrogenation of heavy gas oil which contains sulphur refractory compounds such as 4- methyldibenzotiophene (4-MDBT) and 4,6- dimethyldibenzothiophene (4,6-DMDBT). DBT, 4-MDBT, 3-MDBT, 1-EDBT, 3-EDBT, 4,6-DMDBT, 3,6-DMDBT, 2,8- DMDBT and 4-methylnaphtho[2,1-b]thiophene were selected to calculate the molaraveraged conversion. The conversions of the sulfur containing compounds and phenanthrene were determined as a function of the operating variables: space time (W/Fo DBT), temperature, H2/HC mol ratio and pressure. The Conversions of DBT and 4,6-DMDBT into their reaction products such as Biphenyl (BPH), Cyclohexylbenzene (CHB), Bicyclohexyl (BCH) and 3,4-Dimethylbiyphenyl (3,4-DMBPH) were determined only as a function of space time in the interval of 4000-6000 kgcath/kmol. The results of this work showed that Pt-HY and PdPt-HY are good noble metals catalysts for the hydrodesulfurization of heavy gas oil. Moreover, this study showed that CoMoPd/Pt-HY and CoMoNi/PdPt-HY catalysts are good candidates for deep HDS and hydrogenation of heavy gas oil. It was found that the conversions of sulfur compounds were higher than the conversions provided by the conventional CoMo/Al2O3 catalyst. Also higher hydrogenation of phenanthrene was observed. Deactivation of the catalysts was not observed during the operation. Finally, the study not only contributed to define the technical bases for the preparation of the noble metal catalysts for hydrodesulfurization of heavy gas oil at pilot scale, but also provided technical information for developing the kinetic modeling of the hydrodesulfurization of heavy gas oil with the noble metal catalysts.

L’emploi de cristaux de zéolithe USY comme fonction acide et de phases sulfures de type NiMoS comme fonction hydro/deshydrogénante (H/DH) dispersée sur un liant de type alumine [NiMoS/(_-Al2O3 + USY)] permet l'obtention de catalyseurs bifonctionnels d’hydrocraquage très actifs mais dont la sélectivité en distillats moyens est relativement faible. Une des causes invoquées pour expliquer ces performances est la distance importante entre les sites H/DH et les sites acides qui entraine des réactions secondaires et la formation de produits légers. Dans ce travail, une phase H/DH additionnelle (nickel) a été insérée dans des zéolithes USY par différentes méthodes afin d’obtenir des catalyseurs contenant une phase sulfure localisée au plus proche des sites acides. L’utilisation de zéolithes imprégnées à sec et échangées avec du nickel dans des catalyseurs typiques d’hydrocraquage permet d’obtenir de meilleures activités et sélectivités en distillats moyens en hydroconversion du squalane (2,6,10,15,19,23- hexamethyltetracosane) que l’utilisation de zéolithe ne contenant pas de Ni. L’étude de la relation structure-réactivité des catalyseurs a permis de mettre en évidence que l’amélioration de la proximité entre fonction acide et fonction H/DH est bien à l’origine de l’amélioration des propriétés catalytiques. De plus, l’utilisation d’une zéolithe dans laquelle le nickel a été inséré à la synthèse conduit aussi à des résultats prometteurs. Ce travail ouvre ainsi une voie d’amélioration pour des catalyseurs d'hydrocraquage plus actifs et plus sélectifs en distillats moyens par insertion d’une phase H/DH additionnelle / Hydrocracking bifunctional catalysts can be obtained using USY zeolite crystals as an acid function and NiMoS metal sulfide phase as a hydro/dehydrogenating (H/DH) function dispersed on an alumina binder [NiMoS/(_-Al2O3 + USY)]. These catalysts are very active but have a moderate selectivity towards middle distillates. One of the suggested explanations is the large distance between the two different types of catalytic sites leading to secondary reactions and to the formation of light products. In this work, an additional H/DH phase (nickel) has been inserted in USY zeolites using various methods in order to obtain catalysts in which a sulfided phase is located in the vicinity of the acid sites. The use of impregnated or ion exchanged nickel containing zeolites in a typical hydrocracking catalyst leads to higher activities and middle distillates selectivities in the squalane (2,6,10,15,19,23-hexamethyltetracosane) hydroconversion reaction than the use of bare zeolites. According to the structure-reactivity relation of the catalysts, these enhancements are ascribed to an increased proximity between the H/DH function and the acid sites. Moreover, the use of a synthesized Ni-zeolite leads to promising results. The use of an additional H/DH phase as an optimization route for the production of more active and selective hydrocracking catalysts is then clearly supported by this work