Unraveling enhanced activity, selectivity, and coke resistance of Pt-Ni bimetallic clusters in dry reforming

Abstract

By introducing Pt atoms into the surface of reduced hydrotalcite (HT)-derived nickel (Ni/HT) catalysts by redox reaction, we synthesized an enhanced active and stable Ni-based catalyst for methane dry reforming reaction. The bimetallic Pt-Ni catalysts can simultaneously enhance the catalyst activity, increase the H2/CO ratio by suppressing reverse water-gas shift reaction, and enhance the stability by increasing the resistance to the carbon deposition during the reaction. Kinetic study showed that 1.0Pt-12Ni reduces the activation energy for CH4 dissociation and enhances the catalytic activity of the catalyst and lowers the energy barrier for CO2 activation and promotes the formation of surface O∗ by CO2 adsorptive dissociation. It is beneficial to enhance the resistance to the carbon deposition and prolong its service life in the reaction process. In addition, density-functional theory calculations rationalized the higher coke resistance of Pt-Ni catalysts where CH is more favorable to be oxidized instead of cracking into surface carbon on the Pt-Ni surface, compared with Ni(111) and Pt(111). Even if a small amount of carbon deposited on the Pt-Ni surface, its oxidation process requires a lower activation barrier. Thus, it demonstrates that the bimetallic Pt-Ni catalyst has the best ability to resist carbon deposition compared with monometallic samples.