(513c) Correlating Oxidation State Changes in Ga-Based Catalysts with Propane Dehydrogenation Activity

Operando X-ray absorption spectroscopy can provide insight into changes in metal oxidation state even under the demanding conditions of propane dehydrogenation. The evolution of oxide-supported Ga sites under reducing conditions (either H₂, propane, or a mixture thereof) at elevated temperatures (450-550 °C) was monitored along with conversion as a function of time on-stream. Reduction of Ga(III) to Ga(I) by H₂ occurs with varying ease depending on the oxide support, and can be quantified using the XANES signatures for each oxidation state. However, these changes do not correlate with propane dehydrogenation activity. Instead, new spectroscopic signals appear that suggest the resting state of Ga in the catalytic cycle is Ga(III).