• • MoVTeNbOx mixed oxides achieve >80% selectivity to ethylene in ethane ODH at ~400°C, but conversion remains <30%, underscoring the conversion–selectivity trade-off that limits industrial viability.
• • Silver-based catalysts for propylene epoxidation, such as Ag-MoO3/ZrO2, exhibit propylene oxide selectivity up to 50–60% at low conversion (<5%), with chloride modification enhancing selectivity but posing corrosion risks.
• • Copper-based catalysts, including Cu2O nanocrystals with controlled {100} facets, achieve propylene oxide selectivity >60% at ~200°C, but require precise facet engineering to suppress combustion.
• • In situ UV-vis studies reveal that electrophilic oxygen species (O2−, O−) favor epoxidation, while nucleophilic O2− leads to combustion; controlling their dynamic evolution is critical for selectivity.