In this presentation, the self-assembly of pre-formed pentagonal building blocks and the lattice termination will be discussed for both the M1 [8] and trigonal phases. This assembly process can result in a range of materials from very well ordered crystals to highly disordered or poorly crystallized and intergrown phases [9]. The assembly of the pentagonal subunits to produce crystalline forms can have 2-, 3-, or 4-fold rotational symmetry depending on how the subunits are linked. Of the crystalline phases that have been studied so far, only the M1 structure contains the unique linking site configuration that we associate with selective oxidation activity for propane (amm)oxidation. Evidence for enhanced thermal motion within the M1 active site has been obtained recently from STEM imaging at elevated temperatures [10], whereas, the pentagonal ring sites do not show this enhancement. This active site configuration can be found even in specimens that show M1-type order only over short correlation lengths, which is consistent with observations of catalytic activity in materials that appear to be “X-ray amorphous”.

Compositional inhomogeneity and lattice dynamics in the M1 catalyst: Implications concerning active sites for propane oxidation

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.