The Influence of Support on the Low-Temperature Activity of Pd in the Reaction of CO Oxidation
1996; Elsevier BV; Volume: 161; Issue: 2 Linguagem: Inglês
10.1006/jcat.1996.0213
ISSN1090-2694
AutoresSvetlana Pavlova, Vladіslav Sadykov, N. N. Bulgakov, Mikhail N. Bredikhin,
Tópico(s)Catalysts for Methane Reforming
ResumoThe unsteady and steady-state kinetics of low-temperature CO oxidation over Pd supported on TiO2, SiO2, and Al2O3were investigated by using pulse/flow microcatalytic installation.In situFourier-transformed IR spectroscopy was used to monitor Pd surface under reaction conditions. The kinetic parameters were found to differ considerably from those typical for the high-temperature region. Room-temperature CO oxidation was demonstrated to be structure-sensitive and to proceed via interaction between weakly bound CO and oxygen located at defect centers. Analysis by a semiempirical interacting bonds method showed weakly bound forms of CO to appear due to cooperative Pd–Pd bond rearrangement induced by CO adsorption/desorption processes, while oxygen incorporation into the subsurface layer hinders this reconstruction, thus strengthening Pd–CO bond. In the range of 298–373 K, transition to a mechanism of the usual Langmuir–Hinshelwood type occurs, affecting observed kinetic features of the reaction.
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