New Uniform Solid Catalyst for the Low-Temperature Oxidation of Carbon Monoxide:  A Triple-Layered Rare Earth Perovskite Containing Co and Cu Ions

Abstract

Oxygen reactivity and catalytic activity of the cobalt-containing layered defect perovskites, YBa 2 Cu 2 CoO 7+δ and LaBa 2 Cu 2 CoO 7+δ , in comparison with LaBa 2 Cu 3 O 7-δ have been investigated employing temperatureprogrammed desorption (TPD) and temperature-programmed surface reactions (TPSR) in the stoichiometric and catalytic mode using carbon monoxide as a probe molecule. TPD studies showed evidence for the presence of two distinct labile oxygen species, one at (0 0 1/2) sites and the other at (0 1/2 0) sites in LaBa 2 Cu 2 CoO 7+δ against a single labile species at (0 1/2 0) in the case of two other oxides. The activation energies for the catalytic oxidation of carbon monoxide by oxygen over LaBa 2 Cu 3 O 7-δ , YBa 2 Cu 2 CoO 7+δ , and LaBa 2 Cu 2 -CoO 7+δ have been estimated to be 24.2, 15.9, and 13.6 kcal/mol, respectively. The reactivity and catalytic activity of the oxide systems have been interpreted in terms of the structural changes brought about by substituents, guided by a directing effect of the larger rare earth cation. TPSR profiles, structural analysis, and infrared spectroscopic investigations suggest that the oxygen present at (0 0 1/2) sites in the case of LaBa 2 Cu 2 CoO 7+δ is accessible to catalytic oxidation of CO through a Mars-Van Krevelen pathway. Catalytic conversion of CO to CO 2 over LaBa 2 Cu 2 CoO 7+δ occurs at 200°C. The enhanced reactivity is explained in terms of changes brought about in the coordination polyhedra around transition metals, enhanced basal plane oxygen diffusivity, and redox potentials of the different transition metal cations.

Noble metal ion substituted CeO2 catalysts: Electronic interaction between noble metal ions and CeO2 lattice

“…This property has the following consequences toward CO oxidation: Indeed, YBa 2 Cu 3 O 7 has been found to be a good CO oxidation catalyst [38,39], because, one oxygen from YBa 2 Cu 3 O 7 is utilized for CO oxidation. Exposure to molecular oxygen to YBa 2 Cu 3 O 6 , the compound is regenerated qualifying it to be a catalyst.…”

A new in situ methodology for the quantification of the oxygen storage potential in perovskite-type materials

“…4 Although the use of perovskites as catalysts, photocatalysts and electrocatalysts is widely accepted, only few trials were made to identify and quantify the active species responsible for their activity. 12,[27][28][29] The temperature programmed methods are widely used to study the availability of labile oxygen or the reactive oxygen at high temperature, but they fail in the determination of the in situ reactive oxygen. 12,[27][28][29] The temperature programmed methods are widely used to study the availability of labile oxygen or the reactive oxygen at high temperature, but they fail in the determination of the in situ reactive oxygen.…”

“…10,25 In most cases, the assessment of material goodness is simply made using the material in an applicative process, 11,26 or following the degradation of the materials via Temperature Programmed Reduction (TPR), Oxidation (TPO), Desorption (TPD) and O 2 -pulse measurements. 12,[27][28][29] The temperature programmed methods are widely used to study the availability of labile oxygen or the reactive oxygen at high temperature, but they fail in the determination of the in situ reactive oxygen. Other methods used to investigate qualitatively or quantitatively the oxygen availability of perovskite-type materials include X-ray photoelectron spectroscopy, 29,30 secondary ion mass spectrometry, isothermal isotope exchange 31 and oxygen isotopic exchange 28 for the surface oxygen, and thermogravimetric analyses, 10,11,32 diffuse reectance FTIR spectroscopy, 33 near edge X-ray absorption ne structure 11 and oxygen isotopic exchange 28 for the bulk oxygen.…”

Low Temperature Formation of Ruddlesden–Popper‐Type Layered La2CoO4±δ Perovskite Monitored via In Situ X‐ray Powder Diffraction

“…Beside energy‐oriented applications, such as in SOFCs, RP‐type perovskites are used as catalysts in numerous heterogeneously catalyzed reactions. Among others, they are used as catalysts for oxidation of CO, decomposition of NO, combustion of methane, decomposition of N 2 O, or oxygen evolution reaction (OER) …”