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Structure and reactivity of PdO{sub x}/ZrO{sub 2} catalysts for methane oxidation at low temperatures

Journal Article · · Journal of Catalysis
; ;  [1];  [2]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering
  2. Univ. Nacional Autonoma, Ensenada (Mexico). Inst. of Physics
The kinetics of methane combustion at low temperatures are consistent with a Mars-van Krevelen redox mechanism involving the activation of methane on site pairs consisting of oxygen atoms and oxygen vacancies on the surface of PdO{sub x} crystallites. H{sub 2}O strongly inhibits methane oxidation rates by titrating surface vacancies in a quasi-equilibrated adsorption-desorption step. Initial activation periods during methane oxidation are related to the presence of oxygen-deficient PdO{sub x} crystallites, which contain stronger Pd-O oxygen bonds and increase their oxygen content during steady-state combustion reactions. Strong Pd-O bonds in small crystallites and in oxygen-deficient PdO{sub x} also lead to the observed decrease in methane oxidation turnover rates as crystallite size decreases or as samples are treated at temperatures above those required for PdO-to-Pd decomposition.
OSTI ID:
289439
Journal Information:
Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 179; ISSN 0021-9517; ISSN JCTLA5
Country of Publication:
United States
Language:
English

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