Complete confinement of Ce/Ni within SiO2 nanotube with high oxygen vacancy concentration for CO2 methane reforming

Abstract

CO2 reforming of methane (DRM) is currently one of the most promising processes to convert two green-house gases: CH4 and CO2 to value-added syngas, boosting CO2 utilization and promoting carbon neutralization. However, a major challenge of inexpensive and active Ni-based catalysts for DRM reactions is their easy sintering and carbon deposition issues. Herein, a series of bimetallic Ce/Ni nanoparticles completely confined within SiO2 nanotube (NT) catalysts were synthesized by the precipitation and coating method. Compared with Ni@SiO2, bimetallic xCe/Ni@SiO2 catalysts have higher specific activities for DRM reaction. In addition, 20Ce/Ni@SiO2 shows high and stable CH4 and CO2 conversions of 76.3% and 80.1%, respectively at 700 °C for 80 h. High Ni sintering resistance, high concentration of surface Ni and oxygen vacancies (Vo), high carbon resistance contribute to its outstanding DRM performance. The CO2 activation mechanisms via CeO2 and H* was revealed via in-situ DRIFTS study. The preparation method to completely confine bimetallic nanoparticles within SiO2 NTs sheds light on the design of other confined bi/tri-metallic catalysts with high sintering resistance to be applied in other high temperature reactions.