Ceria-modified nickel supported on porous silica as highly active and stable catalyst for dry reforming of methane

摘要

Addition of CeO2 was regarded as a promising strategy to enhance the carbon resistance of nickel-based catalysts for dry reforming of methane (DRM) due to the high concentration of reactive oxygen species with excellent oxidation capacity. In this work, ceria-modified porous silica supported nickel catalysts (Ni-CeX-Y/SiO2) were prepared by "one-pot" method and employed to catalyze DRM reaction. Introduction of CeO2 hindered the formation of 1:1 Ni-phyllosilicate species and weakened the interaction between Ni and silica. The surrounding CeO2 on Ni nanoparticle efficiently prevented the nickel sintering. The number of active oxygen species gradually increased with increasing CeO2 loading, which was beneficial to improve the carbon resistance by means of participating in the oxidation of carbon. Therefore, Ni-CeX-Y/SiO2 catalysts exhibited lower carbon deposition and graphitization degree. Ni-Ce5-2/SiO2 and Ni-Ce5-3/SiO2 possessed strong anti-sintering ability and carbon resistance, showing relatively good stability that CH4 conversion decreased from 81.3 to 75.6% and 82.2 to 78.2% over 24 h time on stream. Kinetic study confirmed that introduction of CeO2 decreased the activation energy of CH4 decomposition and CO2 dissociation, hence enhancing the catalytic activity and carbon resistance.