Role of catalyst support over PdO–NiO catalysts on catalyst activity and stability for oxy-CO2 reforming of methane

PdO–NiO catalysts over several commercial metal oxides were synthesized using incipient wet impregnation method. The activities of PdO–NiO catalysts for syngas production via oxy-CO2 reforming of methane were investigated at temperatures ranging from 500 °C to 800 °C in a fixed-bed continuous-flow reactor. The PdO–NiO/Y2O3 and PdO–NiO/Al2O3 catalysts show very high CH4 and CO2 conversions due to the formation of metal-support compound on these catalysts. On the PdO–NiO/Y2O3 catalyst, Pd interacts with Y2O3 support to form PdxOyYz compound while Ni interacts with Al2O3 support to form NiAl2O4 spinel compound on the PdO–NiO/Al2O3 catalyst. However, the amount of deposited carbon on the spent PdO–NiO/Y2O3 catalyst is much lower than the one on the PdO–NiO/Al2O3 catalyst due to the presence of surface β-oxygen species and ability of Y2O3 to form oxycarbonate species, resulting in stable catalytic performance without noticeable deactivation during reaction. The surface β-oxygen species are found to promote cracking of C–H bond in CH4 while the oxycarbonate species can oxidize the deposited carbon, respectively, hence leading to the stability of the PdO–NiO/Y2O3 catalyst.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (125 K)Download as PowerPoint slideHighlights► Effect of catalyst supports over PdO–NiO catalysts for oxy-CO2 reforming of methane. ► PdO–NiO/Y2O3 catalyst shows formation of metal-support compound. ► Formation of metal-support compound results in small metal size. ► Small metal size of PdO–NiO/Y2O3 catalyst is required for high catalytic activity. ► Surface β-oxygen species on PdO–NiO/Y2O3 catalyst can promote cracking of C–H bond in CH4 to CO and H2.