Partial oxidation of methane over high coke- resistant bimetallic Pt-Ni/CeO2 catalyst: Profound influence of Pt addition on stability

We have developed a bimetallic Pt-Ni/CeO2 catalyst by straightforward citric acid complex combustion method for low-temperature partial oxidation of methane. Furthermore, we also compared the catalytic performance of bimetallic Pt-Ni/CeO2 with monometallic Ni/ CeO2 catalysts. The bimetallic 0.5%Pt-2.5%Ni/CeO2 (PNC2.5) catalyst exhibited >99% con-version of methane with a H2/CO ratio of 2, whereas monometallic 2.5%Ni/CeO2 (NC2.5) catalyst showed-92% methane conversion with a H2/CO ratio of 1.9 at 700 degrees C. In addition, the PNC2.5 catalyst does not show any deactivation and structural changes during 500 h time-on-stream (TOS), also confirmed by TEM, Raman, and TGA analysis. Conversely, a substantial activity loss (-61%) was noticed in the NC2.5 catalyst owing to the coking and sintering of Ni species. The excellent performance of the PNC2.5 catalyst can be attributed to the modified electronic-structural properties. The activation of CH4 molecules was studied by DFT calculation over Pt-Ni/CeO2(111) and Ni/CeO2(111) model systems, which explain the promotional effect of Pt in the methane C-H bond activation with-8 kcal/mol reduction in the activation barrier.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

We have developed a bimetallic Pt-Ni/CeO2 catalyst for low-temperature partial oxidation of methane using a straightforward citric acid complex combustion method. The Pt-Ni/CeO2 catalyst exhibited significantly higher catalytic activity and stability compared to the monometallic Ni/CeO2 catalyst, which can be attributed to the modified electronic-structural properties.