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.

Effect of Surface Temperature on the Distribution and Reactivity of Rh Active Sites for CO Oxidation

“…Oxidation of CO is a fundamental reaction that plays a critical role in many technologically important systems such as the water gas shift reaction, [13–18] catalytic converters, [19–21] and for the purification of hydrogen used in proton‐exchange membrane fuel cells, [22–25] In addition, CO is an excellent probe molecule for the characterization of surfaces [26–30] . As a result, the adsorption of CO and its oxidation have been extensively studied in the SAC field.…”

“…However, there are major challenges in the SAC field including identification of the active site and its local coordination, determining reaction mechanisms, identifying the catalytically relevant charge state of the single metal atoms, and understanding the role of the support. [7][8][9][10][11][12] Oxidation of CO is a fundamental reaction that plays a critical role in many technologically important systems such as the water gas shift reaction, [13][14][15][16][17][18] catalytic converters, [19][20][21] and for the purification of hydrogen used in proton-exchange membrane fuel cells, [22][23][24][25] In addition, CO is an excellent probe molecule for the characterization of surfaces. [26][27][28][29][30] As a result, the adsorption of CO and its oxidation have been extensively studied in the SAC field.…”