Role of Metal Identity and Speciation in the Low-Temperature Oxidation
of Methane over Tri-Metal Oxo Clusters
Abstract
Clarity as to the role of metal identity and oxidation state in
effecting redox and acid-catalyzed turnovers is oftentimes precluded by
a high degree of heterogeneity in site speciation, a limitation that can
be overcome through the use of well-defined poly-metal clusters hosted
by metal organic framework materials- accomplished in the present case
using MIL-100(M) for the low temperature oxidation of methane with N2O.
Transient kinetic data point to a) methoxy species mediating methane
conversion, b) partial and deep oxidation occurring over metal sites
distinct in oxidation state, c) chromium clusters amplifying the
propensity toward C-C bond formation, and d) the relative velocity of
propagation of water and methanol concentration fronts playing a
determinative role in maximizing C2 oxygenate selectivity. The study
captures the utility of using classes of materials inherently endowed
with a high level of definition and uniformity in advancing the
elucidation of structure-catalytic property relationships.