Hydrodeoxygenation of Phenolic Compounds by Sulfided (Co)Mo/Al₂O₃Catalysts, a Combined Experimental and Theoretical Study

Abstract

-l'hydrogénation du noyau aromatique suivie par la rupture de la liaison C sp3 -O (voie HYD, (hydrogenation of the aromatic ring followed by Csp3-O bond cleavage)) ; -la rupture directe de la liaison C sp2 -O (voie de DésOxygénation Directe -DOD). Ces deux voies sont favorisées en présence du catalyseur promu par le cobalt (CoMo/Al 2 O 3 ). La présence du groupe éthyle permet d'améliorer la voie DOD mais conduit à une diminution de la voie HYD. Les études menées par spectroscopie IR (InfraRouge) montrent que le phénol est majoritairement dissocié sur ces catalyseurs alors que le 2-éthylphénol semble plutôt adsorbé de façon non-dissociative. Les énergies d'adsorption de ces deux réactifs ainsi que celles des intermédiaires réactionnels impliqués sur les phases promues et non-promues ont été déterminées par calculs DFT (Density-Functional Theory). Elles permettent de rationnaliser les résultats expérimentaux obtenus. DFT (Density-Functional Theory) confirm these findings and allow rationalizing the catalytic activity trends observed experimentally. Abstract

Recent Insights in Transition Metal Sulfide Hydrodesulfurization Catalysts for the Production of Ultra Low Sulfur Diesel: A Short Review

“…Although most of the catalytic reactions are directly related to the nature of the catalyst, the support may improve or reduce their catalytic properties, which is critical at the nanoscale, because the structure and the stability of the catalysts could be affected by the support [213,214]. One of the earliest theoretical efforts to understand the cluster/support interaction was motivated by the difference of catalytic activity presented by Type-I and Type-II CoMoS structures supported on alumina [215,216].…”

Atmospheric hydrodeoxygenation of phenol as pyrolytic‐oil model compound for hydrocarbon production using Ag/TiO2 catalyst

“…Phenol HDO reaction scheme is shown in Figure , which consists of phenol hydrogenolysis (Step 1), phenol hydrogenation (Step 2), cyclohexanol dehydration (Step 3), cyclohexene hydrogenation (Step 4), and benzene hydrogenation (Step 5). Step 1 is commonly known as DDO pathway whereas Steps 2, 3, and 4 belonged to HYD pathway . These HDO pathways were also commonly reported with the use of various supported transition metal catalysts such as Co, Fe, Mo, Ni, Pd, and Pt .…”

“…Step 1 is commonly known as DDO pathway whereas Steps 2, 3, and 4 belonged to HYD pathway . These HDO pathways were also commonly reported with the use of various supported transition metal catalysts such as Co, Fe, Mo, Ni, Pd, and Pt . In the overall gas‐phase reaction, the metal sites catalyzed phenol hydrogenolysis and the hydrogenations of phenol, benzene, and cyclohexene whereas the acid sites catalyzed the dehydration of cyclohexanol intermediate into cyclohexene .…”

“…Phenol is another important model compound being studied as it exhibits single functionality . Several supported Co‐, Fe‐, Mo‐, Ni‐, Pd‐, Pt‐, Rh‐, and Ru‐based catalysts have been studied for phenol HDO in liquid or gas phase . Researchers have classified phenol HDO into three major reaction pathways: (a) direct deoxygenation (DDO) route, (b) hydrogenation–dehydration route (HYD), and (c) tautomerization–deoxygenation route .…”

Estudio computacional del efecto promocional del cobalto en agregados aislados de Mo y Co como modelo de catalizadores de hidrodesulfuración

“…Descubrieron que la presencia de Co disminuye la interacción con los soportes. Badawi y colaboradores llevaron a cabo un estudio experimental y teórico combinado sobre el efecto del agua sobre la estabilidad de los catalizadores MoS y CoMoS en la hidrodesoxigenación de compuestos fenólicos, encontrando que el Co juega un papel promotor de la reacción catalítica y un rol pasivante contra la presencia de agua [7,8]. Borges y Silva utilizaron DFT y un modelo de Coulomb para estimar las fuerzas de enlace con la intención de dilucidar el efecto de Co y Ni en los clústers aislados de MoS frente a la adsorción de tiofeno.…”