Effects of oxide supports on the CO₂ reforming of ethane over Pt-Ni bimetallic catalysts

Catalytic reduction of CO₂ by ethane creates an opportunity to use the shale gas and CO₂ as the raw materials to produce syngas via dry reforming. In the present work, Pt-Ni bimetallic catalysts were investigated on reducible (CeO₂, TiO₂) and irreducible (γ-Al₂O₃, SiO₂) oxides. The results showed that catalysts supported on reducible oxides, especially CeO₂, were more active than those supported on irreducible oxides. Pulse and flow reactor studies and infrared spectroscopy experiments revealed a bi-functional Mars-Van Krevelen redox mechanism on PtNi/CeO₂ and a mono-functional Langmuir-Hinshelwood mechanism on PtNi/SiO₂, providing insights into the effects of reducibility of oxide supports on the reaction kinetics. Additionally, compared with the non-reducible SiO₂, in situ X-ray diffraction (XRD) and pulse reactor analysis revealed that CO₂ could be effectively activated on the reducible CeO₂ and formed surface oxygen species to promote ethane dissociation into active carbon species. Thermogravimetric analysis (TGA), Transmission electron microscopy (TEM) and Raman spectroscopy showed that cokes formed on PtNi/CeO₂ were primarily disordered/amorphous carbon species that could be easily removed during reforming.