Ru4+ ion
in CeO2 (Ce0.95Ru0.05O2−δ):
A non-deactivating, non-platinum
catalyst
for water gas shift reaction
PREETAM SINGH, N
MAHADEVAIAH, SANJIT K PARIDA and M S HEGDE*
Solid State and
Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
e-mail:
mshegde@sscu.iisc.ernet.in
MS received 4
February 2011; revised 6 April 2011; accepted 11 May 2011
Abstract.
Hydrogen is a clean energy carrier and highest energy density
fuel. Water gas shift (WGS) reaction
is an important
reaction to generate hydrogen from steam reforming of CO. A new WGS catalyst,
Ce1−xRuxO2−δ (0≤x≤0.1)
was prepared by hydrothermal method using melamine as a complexing agent.
The Catalyst does
not require any pre-treatment. Among the several compositions prepared and
tested,
Ce0.95Ru0.05O2−δ (5%
Ru4+ ion substituted in CeO2) showed very high WGS
activity in terms of high conversion
rate (20.5μmol.g−1.s−1
at 275◦C)
and low activation energy (12.1 kcal/mol). Over 99% conversion of CO
to CO2
by H2O is observed with 100% H2 selectivity at ≥ 275◦C.
In presence of externally fed CO2 and H2
also, complete
conversion of CO to CO2 was observed with 100% H2
selectivity in the temperature range of
305–385°C. Catalyst
does not deactivate in long duration on/off WGS reaction cycle due to absence
of surface
carbon and
carbonate formation and sintering of Ru. Due to highly acidic nature of Ru4+ ion,
surface carbonate
formation is also
inhibited. Sintering of noble metal (Ru) is avoided in this catalyst because Ru
remains in
Ru4+ ionic
state in the Ce1−xRuxO2−δ catalyst.
Graphical
Abstract. A
novel Ru ion substituted CeO2, Ce0.95Ru0.05O2-δ,
synthesized by
hydrothermal method showed,
nearly 100% CO conversion in the WGS
reaction with conversion rate
20.5 μ mol.g-1.s-1
at 275-C and activation
energy 12.1 kcal/mol.
Keywords. WGS reaction; Ru4+ ion in CeO2; Pt
catalyst; H2 selectivity.