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.