Low-temperature preferential CO oxidation in a hydrogen-rich stream over Pt-NaY and modified Pt-NaY catalysts for fuel cell application

Abstract

Preferential oxidation of CO (CO-PROX) in the hydrogen-rich stream has been carried out over Pt-NaY catalysts containing various Pt loadings along with Fe, Co, and Au. Catalysts have been characterized with inductively coupled plasma-atomic emission spectroscopy, Brunauer, Emmett, and Teller surface area, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature programmed reduction, and Pt dispersion. CO-PROX activities and CO oxidation selectivities are observed to increase with an increase in Pt content. Pt-NaY catalyst with 0.75 wt.% Pt loading shows maximum CO-PROX activity at low temperatures. An increase in space velocity decreases the CO and O₂ conversions, but CO oxidation selectivity increases. A decrease in activity is observed when reformat gas contains around 20% H₂O. During the stability test, no change in CO and O₂ conversions is observed, but a small increase in the CO oxidation selectivity is noticed after 10 h indicating that the Pt-NaY catalyst is a promising candidate for CO-PROX reaction in a hydrogen-rich stream. The Pt-Fe-NaY catalyst shows better activity than the Pt-NaY catalyst but starts deactivating after 10 h. However, activity is observed to decrease over Pt-Co-NaY and Pt-Au-NaY catalysts. Pt-Fe-NaY catalyst with 0.75 and 0.35 wt.% Pt and Fe, respectively, shows better CO-PROX activity at a temperature of 75°C.