Catalytic performance and characterization of Al2O3-supported Pt-Co catalyst coatings for preferential CO oxidation in a micro-reactor

Platinum-cobalt (Pt-Co) catalyst coatings are studied for preferential oxidation of carbon monoxide (PROX) ill hydrogen-rich gas streams. Experimental results show a role for cobalt in improving catalytic activity. The most active catalyst coating can decrease carbon monoxide concentrations from 1% to a value of less than 10 ppm for GHSV values ranging from 40,000 to 120,000 ml g(-1) h(-1). This catalyst coating can work at a wide window of operation ill terms of temperature. Transmission electron microscopy, selected-area electron diffraction, and diffuse reflectance infrared Fourier transform spectroscopy show that the addition of Co forms Pt3Co intermetallic compounds and slightly increases the average particle size. In situ laser Raman spectroscopy reveals the co-existence of Co metal and its oxides on the catalyst surface, due to gradual oxidation of Co by gas phase oxygen within the initial stage of the PROX reaction. The promotional effect of Co during PROX is confirmed and ascribed to this Pt3Co intermetallic compound and the synergetic effect of Co-0 and Co chi+. The high accessibility of the reactant to Pt3Co species appears favorable and crucial for PROX. (C) 2010 Elsevier B.V. All rights reserved.