Portrait of a Selective Oxidation Catalyst

Elisabeth Bordes-Richards, Ali Shekari and Gregory S. Patience 

CTp by holes). Oxygen species (other than 0 ) which are said to be non-selective can form on the surface if the material is not able to provide enough electrons, as shown by the following successive reactions  

Alternatively, the sub-surface or bulk 0 species may diffuse to the surface to refill the vacancy. Note that only reactors operating in a redox decoupling mode, like CFBs, would derive oxygen from the bulk because the oxidation step is carried out in a distinct fluidized-bed reactor. Obviously this diffusion process is slower than the surface re-oxidation by molecular (gaseous) O2, but depending on the cation reducibihty during catalyst equilibration , part of the bulk becomes reduced. At the steady state (rR = rred = Tox) there is a hmited amount of 0 species able to participate in the reaction at each cycle (turn-over). 

Application to VPO Catalysts in n-butane Oxidation to Maleic Anhydride 

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