title: Mechanism of tetralin ring opening and contraction over bifunctional Ir/SiO₂-Al₂O₃ Catalysts.
abstract: The development of cleaner fuels from conventional resources requires the finding of new hydrotreatment processes able to improve the combustion performances of fuels and limit undesirable emissions. In the context of gas oil upgrading by selective ring opening, we have investigated the hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica-alumina. The conversion of tetralin leads to hydrogenation, ring-contraction, and ring-opening products. The selectivity to ring-opening/-contraction products (ROCPs) increases linearly with the acid-metal site ratio and can be tuned by modifying the metal loading, the metal nanoparticle size, or the support composition. From the combination of catalytic tests at variable conversion and the products identification by two-dimensional gas chromatography, a mechanistic reaction scheme has been established. Aromatic ROCPs are formed through purely acidic steps, whereas the formation of saturated ROCPs mostly involves bifunctional reaction steps. Iridium-catalyzed hydrogenolysis appears to be a minor pathway with respect to iridium-catalyzed hydrogenation and Brønsted acid catalyzed isomerization.
authors.affiliation: Institut de Recherches sur la Catalyse et l'Environnement de Lyon, IRCELYON, UMR 5256 CNRS & Université Lyon 1, 2 avenue Albert Einstein, 69626 Villeurbanne, France. laurent.piccolo@ircelyon.univ-lyon1.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Piccolo
authors.forename: Salim
authors.initials: S
authors.lastname: Nassreddine
authors.forename: Guy
authors.initials: G
authors.lastname: Toussaint
authors.forename: Christophe
authors.initials: C
authors.lastname: Geantet
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002384:Catalysis; D007495:Iridium / Q000737:chemistry*; D007536:Isomerism; D012822:Silicon Dioxide / Q000737:chemistry*; D013764:Tetrahydronaphthalenes / Q000737:chemistry*
chemical_list: D013764:Tetrahydronaphthalenes; D007495:Iridium; D012822:Silicon Dioxide; C095210:tetralin; D000537:Aluminum Oxide