CuO-CeO2 catalysts for the CO preferential oxidation (CO PROX)

B. SCHONBROD; F. MARIÑO; M. JOBBAGY; G. BARONETTI; M. LABORDE

la Habana, Cuba

Congreso; Hypothesis VI; 2005

Academia Nacional de Ciencias de Cuba

The low-temperature proton exchange membrane fuel cell (PEMFC) has been largely studied and developed for its application in mobile and stationary sources during the last two decades. Since carbon monoxide poisons the electrocatalyst of the fuel cell,PEMFC operation requires CO-free hydrogen (less than 50 ppm). The preferential oxidation of CO (PROX) is the simplest and the least expensive ultimate purification technique. The PROX reaction over supported noble metal catalysts has been extensively studied. However, the high cost of precious metals has encouraged researchers around the world to look for alternative catalysts. In particular, the CuO-CeO2 catalyst has been found to be highly active and exceptionally selective for the preferential oxidation of CO. In this work, CuO-CeO2 catalysts were prepared by homogeneous precipitation by the urea hydrolysis at 90°C. After filtering and drying, samples were calcined in air. The effect of several preparation variables (aging time, calcination temperature, copper content) on both the sample structure and catalytic performance was analyzed. Catalysts and catalyst precursors (non-calcined precipitated samples) were characterized by TGA, SEM-EDAX, XRD and TPR. BET surface area of the samples was determined by N2 chemisorption. For the low copper content samples, our results indicate the existence of at least two different copper species. For higher copper content catalysts, a segregated CuO phase could also be detected. Catalytic tests were carried out in an atmospheric glass fixed bed reactor using a feed consisting of a CO/H2/O2 mixture and N2 as balance. The influence of two important operation conditions, such as the reaction temperature (T = 50-300°C) and the oxygen excess on the catalyst activity and selectivity was evaluated.