Spectroscopic features and reactivity of CO adsorbed on different Au/CeO2 catalysts
نویسندگان
چکیده
An FTIR study of CO adsorption from 120 K up to room temperature on a series of Au–ceria samples is presented. Samples with low gold content (0.7 and 0.6 at%) were prepared by urea gelation/co-precipitation and by cyanide leaching of the high-gold content (5.8 at%) material prepared by deposition–precipitation on La-doped CeO2. The samples were subjected to different pretreatments to collect information on the surface composition under working conditions. An absorption band at 2130–2140 cm−1, not reversible on outgassing and more resistant to oxidation than the usual carbonyl band on Au0 sites, was present due to CO adsorbed on cationic gold clusters. This highly stable species is relevant for hydrogen gas upgrade by removing CO from reformate-type gases at low temperatures. In addition, a broad absorption band in the 2000–2100 cm−1 range was observed after reduction in hydrogen, due to structural and electronic changes of gold. Interestingly, the reduced gold species in ceria can be reoxidized at mild conditions. Light-off of the CO oxidation reaction took place below room temperature on the metallic gold-containing ceria but was delayed until 310 K on the ionic gold-containing sample. TPR and XPS analysis of the fresh and used catalysts corroborated the stability of ionic gold in ceria up to 393 K in the reaction gas mixture. © 2006 Elsevier Inc. All rights reserved.
منابع مشابه
CO Oxidation at the Interface of Au Nanoclusters and the Stepped-CeO2(111) Surface by the Mars-van Krevelen Mechanism.
DFT+U calculations of CO oxidation by Au12 nanoclusters supported on a stepped-CeO2(111) surface show that lattice oxygen at the step edge oxidizes CO bound to Au NCs by the Mars-van Krevelen (M-vK) mechanism. We found that CO2 desorption determines the rate of CO oxidation, and the vacancy formation energy is a reactivity descriptor for CO oxidation. Our results suggest that the M-vK mechanism...
متن کاملCO Oxidation at the Interface between Doped CeO2 and Supported Au Nanoclusters.
DFT+U calculations of CO oxidation by Au13 nanoclusters (NCs) supported on either CeO2 or doped (X-Ce)O2 (X = Au, Pt, Pd, Ti, Ru, Zr) show that doping the CeO2 support accelerates CO oxidation by the Mars-van Krevelen mechanism at the Au-(X-Ce)O2 interface. We find that Au, Pd, Pt, and Ti dopants significantly lower the vacancy formation energy of the CeO2 support and that electron donation fro...
متن کاملComputational Design of a CeO2‐Supported Pd-Based Bimetallic Nanorod for CO Oxidation
Engineering a bimetallic system with complementary chemical properties can be an effective way of tuning catalytic activity. In this work, CO oxidation on CeO2(111)supported Pd-based bimetallic nanorods was investigated using density functional theory calculations corrected by on-site Coulomb interactions. We studied a series of CeO2(111)supported Pd-based bimetallic nanorods (Pd−X, where X = A...
متن کاملMicrowave synthesis of supported Au and Pd nanoparticle catalysts for CO oxidation.
We report the microwave synthesis and characterization of Au and Pd nanoparticle catalysts supported on CeO2, CuO, and ZnO nanoparticles for CO oxidation. The results indicate that supported Au/CeO2 catalysts exhibit excellent activity for low-temperature CO oxidation. The Pd/CeO2 catalyst shows a uniform dispersion of Pd nanoparticles with a narrow size distribution within the ceria support. A...
متن کاملEffect of platinum on Ceria supported Cu catalysts for PrOx process in fuel processors
The CO preferential oxidation (PrOx) is one of the critical steps in hydrogen production and purification for Polymer Electrolyte Membrane Fuel Cell (PEMFC). This reaction was investigated in the presence of excess hydrogen over Cu/CeO2, Pt/CeO2 and Cu-Pt/CeO2 catalysts. The ceria supports was prepared via precipitation method and Cu-Pt/CeO2 catalyst was synthesized by sequential impregnation o...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2007