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
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.