Mechanistic insights into the rapid deactivation of PtIn/Al2O3 catalysts during CO2-assisted propane dehydrogenation

The thermodynamic limitations of conventional propane dehydrogenation (PDH) have motivated the use of CO 2 as a mild oxidant to enhance reaction performance. However, on Pt-based catalysts that are renowned for their high C–H activation capacity, the introduction of CO 2 often leads to rapid catalyst deactivation. Here, we show that the primary cause of this deactivation is CO generated in situ via the reverse water–gas shift (RWGS) reaction. CO strongly adsorbs onto Pt active sites in PtIn/Al 2 O 3 , especially on isolated Pt atoms, with adsorption energies far exceeding those of propane. This preferential adsorption blocks propane from accessing active sites, suppressing dehydrogenation and reducing the number of available catalytic sites. Moreover, CO adsorption promotes Pt nanoparticle sintering, which increases coke deposition and facilitates side reactions, further accelerating deactivation. These findings provide mechanistic insights into the instability of Pt-based catalysts under CO 2 -assisted PDH (CO 2 -ODHP) and highlight the critical role of CO-induced surface effects in catalyst design and optimization.