A set of thermodynamically consistent equations has been developed for representing the properties of solvating binary liquid mixtures. Chemical interactions between solute and solvent are taken into account by K, an equilibrium constant for complex formation; physical forces between solute, solvent, and complex are represented by van Laar equations through a single physical interaction parameter, a. Solution of the resulting equations by iterative techniques for typical, physically significant values of K and a demonstrates that a wide range of mixture behavior can be represented. Literature data for solubility of acetylene in a variety of solvents have been analyzed and best values of K and a are reported for 13 solvents. The new set of equations give a better fit of the data than that obtained using common two-parameter equations for the excess Gibbs energy, The method developed here can be extended to a variety of cases with strong specific interactions; it provides a basis for general treatment of strongly nonideal liquid mixtures.
Understanding
the O2 adsorption and oxidative activity
on gold-based catalysts is of great significance for gold catalysis.
According to the adsorption behaviors of O2 on Au(111)+, 3Au/Au(111)+, Au19
+, and
Au9/CeO2(111), the electronic nature of why
O2 weakly interacts with free positively charged Au substrate
while it strongly interacts with Au cluster supported on ceria is
well-explained herein. The ceria support serves as an electronic repository,
where it gains and stores electrons from the supported metal cluster
and releases them when the metal cluster interacts with molecular
O2. The possible oxygen species on gold-based catalysts
have been systematically confirmed for the first time. On the Au9/CeO2 modeling catalyst, a peroxide species forms
when O2 locates at the hollow site of Au9, while
a superoxide forms for O2 at the top site of a Ce atom.
It is very interesting to find that Ce3+ ion distributions
in Au
n
/CeO2 catalysts have
diverse possibilities. The superoxide close to Au9 has
the highest oxidative activity. The interface between the Au cluster
and ceria surface is the active site for Au
n
/CeO2 catalysts. The present work sheds light on
understanding the oxidative mechanism of metal/support catalysts,
as well as the development of new catalysts with high performance
at relatively low temperature.
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