Abstract
We report here an investigation on the preferential oxidation of carbon monoxide in an H2-rich stream (CO-PROX reaction) over mono and bimetallic Au-Ag samples supported on macro-mesoporous CeO2. The highly porous structure of ceria and the synergistic effect, which occurs between the bimetallic Au-Ag system and the support, led to promising catalytic performance at low temperature (CO2 yield of 88% and CO2 selectivity of 100% at 60 °C), which is suitable for a possible application in the polymer electrolyte membrane fuel cell (PEMFC). The morphological, structural, textural and surface features of the catalysts were determined by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), N2-adsoprtion-desorption measurements, Temperature Programmed Reduction in hydrogen (H2-TPR), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). Furthermore, the catalytic stability of the best active catalyst, i.e., the AuAg/CeO2 sample, was evaluated also in the presence of water vapor and carbon dioxide in the gas stream. The excellent performances of the bimetallic sample, favored by the peculiar porosity of the macro-mesoporous CeO2, are promising for possible scale-up applications in the H2 purification for PEM fuel cells.
Highlights
In the last few years, polymer electrolyte membrane fuel cells (PEMFC), due to their appealing features such as a low working temperature range (60–100 ◦ C) and high energy efficiency [1,2], emerged as a promising reply to the increasing request of renewable and green energy [3,4]
The addition of gold and/or silver did not alter the morphology of the support
In accordance with the literature, this points to the possible formation of a random alloy of gold and silver [31,32,33,43,44]
Summary
In the last few years, polymer electrolyte membrane fuel cells (PEMFC), due to their appealing features such as a low working temperature range (60–100 ◦ C) and high energy efficiency [1,2], emerged as a promising reply to the increasing request of renewable and green energy [3,4]. The supported platinum group metal catalysts (Pt, Pd, Ru, Rh) efficiently fulfil the requirement of the PROX reaction, especially at high temperatures [7,9,10,11,12,13], but a more economical and performing alternative is represented by the copper-based catalysts [14,15,16,17,18]. Among the various supports utilized, cerium oxide (i.e., ceria, CeO2 ) has a predominant role in the PROX reaction, due to its remarkable redox and oxygen storage capacities [12,13,14,15,16,17,18,19,20,21]
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