Gas-Phase Hydrogen-Atom Measurement above Catalytic and Noncatalytic Materials during Ethane Dehydrogenation

The role of a solid surface for initiating gas-phase reactions is still not well understood. The hydrogen atom (H) is an important intermediate in gas-phase ethane dehydrogenation and is known to interact with surface sites on catalysts. However, direct measurements of H near catalytic surfaces have not yet been reported. Here, we present the first H measurements by laser-induced fluorescence in the gas-phase above catalytic and noncatalytic surfaces. Measurements at temperatures up to 700 degrees C show H concentrations to be at the highest above inert quartz surfaces compared to stainless steel and a platinum-based catalyst. Additionally, H concentrations above the catalyst decreased rapidly with time on stream. These newly obtained observations are consistent with the recently reported differences in bulk ethane dehydrogenation reactivity of these materials, suggesting H may be a good reporter for dehydrogenation activity.

Automated summary

The role of solid surface in initiating gas-phase reactions, particularly the interaction between hydrogen atoms and surface sites, is still not well understood. This study presents the first measurements of hydrogen concentrations by laser-induced fluorescence in the gas-phase above catalytic and noncatalytic surfaces. The results show that hydrogen concentrations are highest above inert quartz surfaces compared to stainless steel and a platinum-based catalyst, and concentrations above the catalyst decrease rapidly with time on stream. These findings support the previously reported differences in bulk ethane dehydrogenation reactivity of these materials, suggesting hydrogen may serve as a good indicator for dehydrogenation activity.