الفهرس 
Perovskites and their Structure’s CrystallographyOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
In this study, hierarchically porous perovskite catalysts of a general formula
ABO3 concerning with three sample’s categories; Intrinsic perovskites (BaMnO3
(BMO) and SrMnO3 (SMO)), their A-site substituted perovskites; modified by
substitution of the A-site (Ba+2) with a cation of the same oxidation state as Sr+2
(Ba0.5Sr0.5MnO3 (BSMO) and Ba0.5Sr0.5FeO3 (BSFO)) and their B-site substituted
ones; modified by substitution of B-site (Mn+4) using cation with different
oxidation state like Fe+3 (BaMn0.5Fe0.5O3 (BMFO) and SrMn0.5Fe0.5O3 (SMFO)),
were prepared using hydrothermal method. Their characteristic properties were
investigated by XRD, FTIR, Raman spectroscopy, XPS, N2 sorption, TEM, NH3-
CO2-TPD, SEM and EDX. The prepared perovskite samples were modified in
order to improve acid/base character and to enhance their effectiveness as catalysts
especially in oxidation reactions. The role of A and B-site substitutions have been
tested for oxidative coupling of primary alcohols (a methanol/ ethanol mixture of
molar ratio ” " ~ " ” 1) into value-added products. The data indicate that, acrolein,
acetaldehyde and formaldehyde were found to be the main products under different
reaction condition (temperature and flow rate) using different perovskite catalysts.
The highest catalytic performance was achieved using the BaSrMnO3 perovskite
catalyst, in which the acrolein selectivity reached 62% (T=300 °C,
MetOH/EtOH=1, LHSV=10 h−1), followed by SrMnFeO3, BaSrFeO3, BaMnFeO3,
SrMnO3 then BaMnO3, respectively. Introduction of basic elements led to an
increase in the number of acid/base pairs then to an improvement of the target
molecule yields, which elucidates high acrolein selectivity. The high activity was
attributed to the significant high rate of C- C bond formation over BaSrMnO3
relative to others. These catalysts propose promising yields of acrolein which make
it a superb choice to be effective in a viable process.