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Catalytic Consequences of the Thermodynamic Activities at Metal Cluster Surfaces and Their Periodic Reactivity Trend for Methanol Oxidation
Author(s) -
Tu Weifeng,
Chin YaHuei Cathy
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201405232
Subject(s) - chemistry , enthalpy , oxygen , reactivity (psychology) , reaction rate constant , catalysis , metal , kinetics , activation energy , entropy of activation , methanol , chemical kinetics , thermodynamics , inorganic chemistry , organic chemistry , medicine , physics , pathology , quantum mechanics , alternative medicine
The periodic reactivity trend and the connection of kinetics to the thermodynamic activity of oxygen are established for the oxidation of methanol on metal clusters. First‐order rate coefficients are a single‐valued function of the O 2 ‐to‐CH 3 OH ratio, because this ratio, together with the rate constants for O 2 and CH 3 OH activation, determine the oxygen chemical potential, thus the relative abundance of active sites and bulk chemical state of the clusters. CH 3 OH activation rate constants on oxygen‐covered Ag, Pt, and Pd and on RuO 2 clusters vary with the metal–oxygen binding strength in a classical volcano‐type relation, because the oxygen‐binding strength directly influences the reactivities of oxygen as H abstractors during the kinetically relevant CH 3 OH activation step. The differences in oxygen thermodynamic activity lead to five orders of magnitude variation in rates (Pt>Pd>RuO 2 >Ag, 373 K), because of its strong effects on the activation enthalpy and more prominently activation entropy in CH 3 OH activation.