8
G.S. Mishra, A. Kumar / Applied Catalysis A: General 429–430 (2012) 1–8
rearrangement. Therefore, the most important step is the formation
of carbenium ions and their rearrangement on the heterogenized
catalyst surface. Although the mechanistic details are not yet clear
precisely [32–35], one can consider that n-hexane and n-heptane
reactions from alkylcarbenium ions first. In our system, they are
initially formed by reaction of n-alkanes with H2 in presence of Re
catalyst (Scheme 3, steps 1 and 2). The acidic nature of the catalyst
from their linear counterparts improving the burning efficiency of
fuel.
Acknowledgments
The author expresses his gratitude to Foundation of Science and
Technology (FCT), Portugal, for “Ciência 2007” and partial finan-
cial support under Project PTDC/EQU-ERQ/110825/2009. We also
thank Prof. P. Santos (UTAD) for valuable discussion, Kelly Machado
(
see above TPD analysis) also favors the formation of carbenium
ions [34]. Once the alkylcarbenium ions are formed, this ion under-
goes either through cyclization forming adsorbed cyclic species
(UTAD) for some useful help and the Analytical Laboratory, Instituto
(
(
step 4) or a simple bond shift/bond cleavage forming mono branch
step 5) or di-branched species (steps 6–8).
Superior Técnico, IST, Lisbon.
In this regard, the ␣-, ␣´ - and ␥-adsorbed species are formed
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