Nanosized Pd/Pt and Pd/Rh Catalysts for Naphthalene Hydrogenation and Hydrogenolysis/Ring-opening |
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Authors: | Stefania Albonetti Giovanni Baldi Andrea Barzanti Enrique Rodriguez Castellon Antonio Jimenz Lopez Dolores Eliche Quesada Angelo Vaccari |
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Affiliation: | (1) Dipartimento di Chimica Industriale e dei Materiali, Alma Mater Studiorum -Università di Bologna, INSTM-UdR Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy;(2) Colorobbia Italia, Via Pietramarina 53, 50053 Sovigliana Vinci Fi, Italy;(3) Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain |
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Abstract: | Pd/Rh and Pd/Pt catalysts supported on two different mesoporous materials – a Zr-doped MCM-41-type silica [Si/Zr = 5 w/w (SiZr)] and a commercial silica-alumina [Si/Al = 40:60 w/w (SiAl)] – were prepared by incipient wetness impregnation using nanosized suspensions of alloy particles prepared by polyol-mediated synthesis in diethylene glycol (DEG). The catalytic behaviour of these catalysts was investigated in the hydrogenation and hydrogenolysis/ring-opening of naphthalene at 6.0 MPa, by checking the role of both the main reaction conditions (temperature, contact time and H2/naphthalene molar ratio) and increasing amounts of dibenzothiophene (DBT). The catalysts supported on SiAl showed higher activity than catalysts supported on SiZr, thus suggesting that activity is favoured by higher acidity of the support and/or higher interaction of the nanosized metal particles with the support. While using the SiZr support, weaker metal-support interactions took place by forming catalysts with bigger metal and/or metal oxide particles. Besides, the catalyst with lowest noble-metal content (0.3 wt.%) (SiAl-0.3Pd/Pt-5) had the greatest acidity and metal surface and, consequently, the highest activity. Furthermore, it exhibited a good thiotolerance in presence of increasing amounts of DBT in the feed, thus maintaining a high catalytic activity in the hydrogenation of naphthalene, although with decreased yield in trans- and cis-decalin (decahydronaphthalene or DeHN) and high-molecular-weight compounds (H.M.W.), with a corresponding increased yield in the partially hydrogenated tetralin (tetrahydronaphthalene or TeHN). |
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Keywords: | naphthalene dibenzothiophene hydrogenation hydrogenolyisis/ring-opening Pd/Pt Pd/Rh supported catalysts nanosized catalysts polyol-mediated synthesis Si/Al Si/Zr MCM-41 |
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