Carbon nanotube-supported Pt-Co bimetallic catalysts for preferential oxidation of CO in a H2-rich stream with CO2 and H2O vapor

Carbon nanotube-supported Pt-Co bimetallic catalysts (Pt-Co/CNTs) are prepared for preferential oxidation of CO in a H-2-rich stream. The results indicate that the addition of Co into the Pt/CNT catalyst significantly improves catalytic performance, making it superior to other carriers supporting the same composition of Pt-Co. Optimized bimetallic Pt-Co/CNT catalyst can preferentially oxidize dilute CO in a H-2-rich stream at a wide temperature window of 313-433 K. At a temperature of 353 K and a H-2-rich stream with 1% CO, 0.7-0.8% 02, 20% H2O, 25% CO2 and 50% H-2 balanced with N-2, this catalyst can afford 100% CO conversion with 62-71% O-2 selectivity for over 100 h. The transmission electron microscopic images reveal that the metal nanoparticles are uniformly dispersed on the surfaces of CNTs with an average size of approximately 2-3 nm, independent of Co loading. The results of X-ray photoelectron spectroscopy and nanoscale elemental mapping indicate that most of Co species are in the form of CoO, presenting on the Pt domain. Higher performance of the Pt-Co/CNT is attributed to the interactions between the Pt nanoparticles and CoO, those are supported on CNT surfaces. (C) 2011 Elsevier B.V. All rights reserved.