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Mechanism of Tetralin Ring Opening and Contraction over Bifunctional Ir/SiO 2 ‐Al 2 O 3 Catalysts
Author(s) -
Piccolo Laurent,
Nassreddine Salim,
Toussaint Guy,
Geantet Christophe
Publication year - 2012
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200080
Subject(s) - tetralin , hydrogenolysis , bifunctional , catalysis , iridium , isomerization , chemistry , bifunctional catalyst , chemical engineering , organic chemistry , engineering
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.