Design and fabrication of an automated temperature programmed reaction system to evaluate 3-way catalysts Ce1−x−y ,(La/Y) x Pt y O2−δ

Gayen, Arup; Baidya, Tinku; Ramesh, Ganduri; Srihari, R.; Hegde, M. S.

doi:10.1007/bf02708765

Cited by 19 publications

(12 citation statements)

References 14 publications

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“…This confirms that Pt ions are substituted in the lattices of Ce 1− x Ti x O 2−δ and CeO 2 for Ce 4+ in catalysts II and III (Figure b,c). Substitution of Pt ion in Ce 1− x La x O 2−δ has also been reported earlier . Detailed studies on the structure of Ce 0.98 Pt 0.02 O 2−δ , Ce 0.83 Ti 0.15 Pt 0.02 O 2−δ , and Ce 0.78 La 0.20 Pt 0.02 O 2−δ by XRD, XPS, TEM, and EXAFS have shown that Pt ion is substituted for Ce 4+ ion and Pt 2+ is the major constituent (78%) in these compounds. ,,, …”

Section: Resultssupporting

confidence: 67%

Nondeactivating Nanosized Ionic Catalysts for Water−Gas Shift Reaction

Sharma

Deshpande

Hegde

et al. 2009

Ind. Eng. Chem. Res.

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The water-gas shift reaction (WGS) is an important reaction to produce hydrogen. In this study, we have synthesized nanosized catalysts where Pt ion is substituted in the +2 state in TiO 2 , CeO 2 , and Ce 1-x Ti x O 2-δ . These catalysts have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), and it has been shown that Pt 2+ in these reducible oxides result in solid solutions like Ti 0.99 Pt 0.01 O 2-δ , Ce 0.83 Ti 0.15 Pt 0.02 O 2-δ , and Ce 0.98 Pt 0.02 O 2-δ . These catalysts were tested for the water gas shift reaction both in the presence and absence of hydrogen. It was shown that Ti 0.99 Pt 0.01 O 2-δ exhibited higher catalytic activity than Ce 0.83 Ti 0.15 Pt 0.02 O 2-δ and Ce 0.98 Pt 0.02 O 2-δ . Further, experiments were conducted to determine the deactivation of these catalysts. There was no sintering of Pt and no carbonate formation; therefore, the catalyst did not deactivate even after prolonged reaction. There was no carbonate formation because of the highly acidic nature of Ti 4+ ions in the catalysts.

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Section: Resultssupporting

confidence: 67%

Nondeactivating Nanosized Ionic Catalysts for Water−Gas Shift Reaction

Sharma

Deshpande

Hegde

et al. 2009

Ind. Eng. Chem. Res.

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“…The catalytic test was done in a temperature-programmed reaction system described elsewhere . The catalyst (40/80 mesh) diluted with SiO 2 (30/60 mesh size) was loaded in the reactor to get a column length of 1.1 cm and the endings were plugged with ceramic wool.…”

Section: Methodsmentioning

confidence: 99%

Origin of activation of Lattice Oxygen and Synergistic Interaction in Bimetal-Ionic Ce_0.89Fe_0.1Pd_0.01O_2−δ Catalyst

et al. 2009

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Flourite-type nanocrystalline Ce0.9Fe0.1O2−δ and Ce0.89Fe0.1Pd0.01O2−δ solid solutions have been synthesized by solution combustion method, which show higher oxygen storage/release property (OSC) compared to CeO2 and Ce0.8Zr0.2O2. Temperature programmed reduction and XPS study reveal that the presence of Pd ion in Ce0.9Fe0.1O2−δ facilitates complete reduction of Fe3+ to Fe2+ state and partial reduction of Ce4+ to Ce3+ state at temperatures as low as 105 °C compared to 400 °C for monometal-ionic Ce0.9Fe0.1O2−δ. Fe3+ ion is reduced to Fe2+ and not to Fe0 due to favorable redox potential for Ce4+ + Fe2+ → Ce3+ + Fe3+ reaction. Using first-principles density functional theory calculation we determine M−O (M = Pd, Fe, Ce) bond lengths, and find that bond lengths vary from shorter (2.16 Å) to longer (2.9 Å) bond distances compared to mean Ce−O bond distance of 2.34 Å for CeO2. Using these results in bond valence analysis, we show that oxygen with bond valences as low as −1.55 are created, leading to activation of lattice oxygen in the bimetal ionic catalyst. Temperatures of CO oxidation and NO reduction by CO/H2 are lower with the bimetal-ionic Ce0.89Fe0.1Pd0.01O2−δ catalyst compared to monometal-ionic Ce0.9Fe0.1O2−δ and Ce0.99Pd0.01O2−δ catalysts. From XPS studies of Pd impregnated on CeO2 and Fe2O3 oxides, we show that the synergism leading to low temperature activation of lattice oxygen in bimetal-ionic catalyst Ce0.89Fe0.1Pd0.01O2−δ is due to low-temperature reduction of Pd2+ to Pd0, followed by Pd0 + 2Fe3+ → Pd2+ + 2Fe2+, Pd0 + 2Ce4+ → Pd2+ + 2Ce3+ redox reaction.

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“…However, the selectivity of N 2 and N 2 O was not measured. Further it was proved that the rate of the reaction increases with the increase in oxide ion vacancies by substituting La or Y in CeO 2 with Pt [69].…”

Section: No X Reduction By Comentioning

confidence: 98%