Unraveling the hydrogen spillover in tandem propane dehydrogenation and reverse water gas shift reaction

The integration of CO 2 into the dehydrogenation of propane (PDH) holds significant promise for both propylene production and greenhouse gas utilization. However, a pivotal challenge lies in mitigating the undesirable dry reforming of propane (DRP), which diminishes propylene selectivity compared to direct PDH processes. Herein, we describe a coupled process that integrates PDH with reverse water gas shift (RWGS) using a tandem catalytic system. The PtSn/Al 2 O 3 analogue performs the dehydrogenation reaction, while an adjacent defective CeO x /Al 2 O 3 at nanoscale acts as the hydrogenation sites for CO 2 . Catalysis and kinetic studies demonstrate the in-situ removal of hydrogen from PtSn/Al 2 O 3 to adjacent CeO x /Al 2 O 3 , facilitated by CO 2 , shifts the quasi-equilibrium of PDH towards propylene production, while suppressing the competitive DRP side reaction. This hydrogen spillover-mediated coupling mechanism enables superior propylene selectivity of ~98.8%, along with high CO 2 (~43.9%) and propane conversion (~44.2%) at 550 °C, outperforming direct PDH (~40.6%). Analysis of CO 2 footprint indicates the PDH-RWGS tandem process has the potential for carbon utilization to mitigate detrimental CO 2 emissions.