الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
n this study the ethanol conversion over Fe2O3-CeO2 nano-composites as
well as the pure CeO2 and Fe2O3 was investigated. The results revealed the
successfull nanocomposites formation by our novel route of the autocombustion
method using citric acid at lower temperature, 300oC. Whereas in
literature, the solid solutions were only produced at least over than 600oC. The
nanocomposites were also achieved by the precipitation method at 300oC.
Porous α-Fe2O3 nanorods and Fluorite structure of CeO2 could be produced
by precipitation method. All catalyst samples under this study exhibited a high
thermal stability up to 1000oC.
The results revealed that the different Fe2O3-CeO2 composites synthesized
by our novel preparation methods maintained the fluorite structure of ceria with
increasing the amount of incorporated Fe. The synergism between cerium and
iron oxide produced a mixed oxide with relatively high reducibility at lower
temperatures.
The XRD data proved the segregation of α-Fe2O3 for the mixed system with
the iron content more than 30%.
The BET and TEM analyses proved the formation of smaller crystallite sizes
for nanocomposites at higher iron contents, where the inhibition of sintering of
ceria was evidenced when a doping cation was introduced inside its cubic
structure.
This phenomenon was proved by the decrease in the ceria crystallite sizes
with the amount of doping agent introduced.
The catalytic activity of such synthesized nanocomposites was examined in
ethanol conversion. The results showed that the dehydration products such as
ethylene and diethyl ether were the main reaction output. Moreover, only tiny
amount of dehydrogenation products were assigned.
The Fe30Ce70 sample, prepared by the auto-combustion method, was the
most active and selective catalyst towards ethylene production (achieving 98%
Conclusion
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at 450oC). Meanwhile, the Fe15Ce85 achieved the highest activity (85.8%) and
selectivity to ethylene. The high activity of the Fe30Ce70 nanocomposite
prepared by both auto-combustion was attributed to the pronounced brönsted
acid sites in this sample, as confirmed by the acidity results.
Additionally, the higher activity of the catalysts prepared by autocombustion
compared with those prepared by co-precipitation was attributed to
the higher SBET values of the former materials.
Finally, the nanocomposites materials synthesized throughout this
work were active, selective and promising candidates for production of
ethylene from ethanol