Mesoporous MAl2O4 (M = Cu, Ni, Fe or Mg) spinels: Characterisation and
application in the catalytic dehydrogenation of ethylbenzene in the
presence of CO2
APPLIED CATALYSIS A-GENERAL, 382 (2):
148-157 (2010)DOI: 10.1016/j.apcata.2010.04.027
Abstract
The catalytic properties of nanostructured MAl2O4 (M = Cu, Ni, Fe or Mg)
were investigated in the dehydrogenation of ethylbenzene with CO2. The
catalysts were characterised by XRD. Raman spectroscopy, textural
properties, acidity (TPD-NH3) and basicity (CO2-TPD) measurements, SEM
and TEM analyses and TPR techniques. XRD revealed the spinel structure
of MAl2O4, except for the NiO, CuO, Fe2O3 and MgO phases. All solids
exhibited the nanostructured features of the SBA-15 template, including
high values of textural properties and morphologies characteristic of
the mesoporous silica. The acidic strength follows the electronegativity
trends of the cations present on the spinel aluminates: CuAl > NiAl >
FeAl and MgAl, which is the inverse order of the basicities. The
selectivities in the dehydrogenation of ethylbenzene with CO2 showed
that styrene was the predominant product for all catalysts except for
those based on Ni, which was highly selective for the production of
toluene. The FeAl2O4 catalyst provided the best catalytic performance
among the solids studied due to the continuous oxidation of Fe3+ sites
by the CO2 from the reaction. This solid has the additional advantage of
being stable over the timescale of the reaction, as compared to the
traditional Fe-based catalysts, due to its nanostructured features. (c)
2010 Elsevier B.V. All rights reserved.