Temperature hysteresis in dry reforming of methane on Ni/SBA-15 catalyst: Low temperature activity originated from the synergy of Ni0 and carbon nanotubes

The origins of temperature hysteresis and low temperature activity on Ni/SBA-15 for dry reforming of methane (DRM) were studied. The catalyst structural evolution under different conditions was characterized by Quasi-in-situ XPS, XRD, TG-MS, TEM, and DRM activity test. When heating up in DRM atmosphere, only at 425 °C (ignition temperature, Tign), H2 and CO were observed, whereas in cooling, the activity dropped to 0% at 295 °C (extinguishing temperature, Text), forming temperature hysteresis. Below Tign, surface Ni0 was oxidized to NiO by CO2 in feed or support oxygen, whereas at Tign, NiO reduction and methane decomposition occurred, generating carbon nanotubes, which improved the oxidation resistance of Ni0, and the synergetic effect of Ni0 and carbon nanotubes led to stable activity at about 300 °C. The insight provides basic information for new catalyst design for low temperature activation of both CH4 and CO2, and understanding of related phenomena.