CO2-Assisted Dehydrogenation of Propane by Atomically Dispersed Pt on MXenes

The catalytic mechanism and performance of MXene-supported atomically dispersed Pt (Pt₁@MXene) in CO₂-assisted propane oxidative dehydrogenation (CO₂-ODHP) was evaluated by density functional theory (DFT) calculations and microkinetic simulations. The Pt single atom (Pt SA) site can promote the cleavage of two C–H bonds in propane to yield propylene via direct dehydrogenation of propane (DDHP), whereas the Pt–MXene interface facilitates the cleavage of the C–O bond in CO₂ and the hydrogenation of O* to H₂O via the reverse water gas shift (RWGS). Degree of rate control and Brönsted–Evans–Polanyi (BEP) correlation analyses revealed that the binding strength of Pt toward C₃H₇* and that of MXene toward O* determined the DDHP and RWGS activities, respectively. The DDHP activity is also highly correlated with the d-band center of the Pt SA and the work function of the Pt₁@MXene surface. Microkinetic simulations showed that the Pt SA anchored on Mo₂CO₂ and W₂CO₂ possessed superior DDHP activity than the Pt(111) surface, although only Pt₁@Mo₂CO₂ presented high activities in both DDHP and RWGS. Furthermore, the high energy barriers of deep dehydrogenations and C–C cracking of C₃ derivatives over Pt₁@Mo₂CO₂ evidenced its high anticoking ability. These predictions suggest Pt₁@Mo₂CO₂ as a promising CO₂-ODHP catalyst.