Correlating Properties of the Mn2O3–Na2WO4/SiO2Catalyst with Statistically Estimated Parameters for the Oxidative Coupling of Methane

Abstract

Identifying key catalyst parameters that govern catalytic performance is a main challenge for many reactions. The complex and convoluted behavior of the Mn₂O₃–Na₂WO₄/SiO₂ catalyst for the oxidative coupling of methane (OCM) makes this task even more challenging. Herein, structure–function correlations are obtained using a simplified methodology that involves cross-referencing statistically estimated reaction kinetic parameters with various experimentally measured catalyst and reaction properties. These correlations and conclusions are shown to be consistent with literature data, which was obtained using advanced in situ techniques. Specifically, these correlations highlight the importance of maintaining highly dispersed Mn₂O₃ particles in a dispersed Na₂WO₄ melt, under OCM conditions. The promotion of OCM is associated with the efficient interaction of the two phases in the gel-like formation, which apparently promotes the release of the catalytic active species. However, it is also shown that under reaction conditions the molten state of the Na₂WO₄ promotes the growth of a separate Mn₂O₃ phase, which enhances CO₂ formation over the OCM by reducing the effective level of interaction between the Mn and the W phases. As a whole, this work not only provides new data but also exemplifies a relatively simple and general tool for identifying catalyst descriptors that govern reaction performance.