As an example on how to understand the catalytic sites at the molecular level by starting with the model catalysts,this report briefly describes three Re-Sn mixed oxide crystallites with well-defined structures and their catalytic performances in the selective ammoxidation of light alkanes.The specific crystalline（100） structures of SbRe2O6 and their interaction with the NH3 reactant play a crucial role in the activation of C-H bonds in alkane molecules.The interaction between the（100） planes and NH3 leads to the formation of adsorbed NHx species and oxygen vacancies,and it specially increases the activity of the lattice oxygen atoms,which constitute the active sites for the C-H bond activation in the ammoxidation reaction.This provides useful information for the design of novel catalysts of the selective oxidation reactions.
