Low temperature reforming of methane with CO₂ over Pt/CeO₂, Ni/CeO₂ and Pt-Ni/CeO₂ catalysts prepared by a solution-combustion method

This study investigates the low temperature reforming of methane with CO2 over mono-metallic (Pt/CeO2 and Ni/CeO2) and bi-metallic (Pt-Ni/CeO2) solid solution catalysts prepared by using a one-pot solution-combustion method. Various analytical techniques were employed to analyze the synthesized catalysts in order to correlate their physicochemical properties to their catalytic activity. Solid solution formation was confirmed by the lattice parameter shifting and Rietveld refinement analysis. Solid-solution formation enhanced the defective oxygen species. The TPR and TPDs studies showed that the synergy between Pt and Ni enhanced the active oxygen species and metal-support interaction of the Pt-Ni/CeO2 catalyst, which are beneficial for the higher adsorption of CH4 and CO2. Pt-Ni/CeO(2 )catalysts have a higher amount of O-2(2-), O(2)(- )species and A(D)/A(F2g) ratio followed by the NC and PC catalysts, as confirmed by the O-2-TPD, XPS and RAMAN analysis. Pt-based catalysts start the DRM reaction at 350 C-degrees, whereas Ni/CeO2 activates at a temperature 100 C-degrees higher than Pt-Ni/CeO2 and Pt/CeO2. At 675 C-degrees, Pt-Ni/CeO2 showed similar to 86% conversion of CO(2 )and CH4 with 100% selectivity of synthesis gas with a H-2/CO ratio of similar to 1, while Pt/CeO2 and Ni/CeO2 shows similar to 46.2 and similar to 59.8% conversion, respectively. DFT calculations showed that the Pt-Ni/CeO2 catalyst required lower activation energy than the monometallic catalyst to activate CH(4 )and CO2. We believe that the synergy between Ni and Pt enhanced the structural and electronic properties of Pt-Ni/CeO2, which is responsible for its excellent performance at low temperature.