1. Introduction
Propylene is an indispensable raw material for numerous products
and direct propane dehydrogenation process is believed to
have good potential with minimum investment as a propylene production
booster, in order to meet growing market demand [1,2]. On
the other hand, propane is a low cost raw material and easily available.
However, the reaction of direct propane dehydrogenation is
highly endothermic (DH298 K
R = 125 kJ/mol of extracted hydrogen)
requiring a relatively high temperature and lower pressure. Therefore
a suitable catalyst of superior stereo-chemistry control is
needed.
Pt–Sn-based catalysts supported on amorphous supports or
zeolites, for propane dehydrogenation have been discussed in
many studies [2–11]. The selection of Sn as a promoter has been
explained in terms of geometric and/or electronic effects [12]. In
the geometric effect, Sn decreases the size of platinum ensembles,
which reduces hydrogenolysis and coking reactions. Sn also modifies
the electronic density of Pt, either by positive charge transfer
from the Snn+ species or the different electronic structures in Pt–
Sn alloys [13]. Therefore we can infer that the dehydrogenation
performance of Pt–Sn-based catalysts depends on the interactions
between the Pt and Sn species as well as the support. The deactivation
of Pt-based catalyst during propane dehydrogenation is fatal,
and mainly due to the aggregation of Pt particles and carbon deposition