Unraveling the hydrogen spillover in tandem propane dehydrogenation and reverse water gas shift reaction
Kaige Tian, Sai Chen, Guodong Sun, Jiachen Sun, Xianhui Wang, Jianhua Cai, Zhiyuan Wang, Donglong Fu, Zhi‐Jian Zhao, Chunlei Pei, Jinlong Gong
Abstract
The integration of CO2 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/Al2O3 analogue performs the dehydrogenation reaction, while an adjacent defective CeOx/Al2O3 at nanoscale acts as the hydrogenation sites for CO2. Catalysis and kinetic studies demonstrate the in-situ removal of hydrogen from PtSn/Al2O3 to adjacent CeOx/Al2O3, facilitated by CO2, 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 CO2 (~43.9%) and propane conversion (~44.2%) at 550 °C, outperforming direct PDH (~40.6%). Analysis of CO2 footprint indicates the PDH-RWGS tandem process has the potential for carbon utilization to mitigate detrimental CO2 emissions. Incorporating CO2 into propane dehydrogenation (PDH) offers great potential for propylene production while simultaneously utilizing greenhouse gases; however, a key challenge is suppressing the undesired dry reforming of propane. Here, the authors present a coupled strategy that combines PDH with the reverse water–gas shift reaction through a tandem catalytic system.