What Is the Active Structure for High-Temperature Direct Dehydrogenative Conversion of Methane by the Supported NiP Catalysts-An in Situ XAFS Study

SiO2-supported NiP catalysts exhibit high activity for the direct dehydrogenative conversion of methane (DCM) to hydrocarbons, such as ethylene, ethane, acetylene, and propylene, at 1173 K. To investigate the real active structure of the SiO2-supported NiP catalysts at high temperature, in situ X-ray absorption fine structure (XAFS) experiments were conducted under the DCM reaction conditions. XAFS results showed that all of the SiO2-supported NiP catalysts with atomic ratios of Ni/P = 1:1, 1:2, 1:3, and 1:4 mainly showed a similar Ni2P structure. The Ni2P structure was stable under the DCM reaction conditions. The high stability of the Ni2P structure ensured robust catalysis for DCM. The high catalytic performance of Ni2P was discussed.