Gas-induced modulation of the surface structure of a Ni/Al2O3-CeO2 catalyst in CO methanation

Abstract

The gas-induced strong metal-support interaction (SMSI) effects have proved to optimize the electronic states of active sites in heterogenous catalysis. A novel approach to tune the surface structure of a 10Ni/7Al2O3-3CeO2 catalyst has been developed by modulating the composition of the reaction atmospheres in CO methanation. The reaction rate was enhanced nearly eight-folds by gas-induced treatment. Multi-Operando/in situ techniques, such as in situ X-ray photoelectron spectroscopy (near ambient pressure, NAP-XPS), in-situ diffraction reflection infrared fourier transform spectroscopy (DRIFTS), Operando Raman spectroscopy and H2 uptakes, reveal that the origin of active sites is due to the great exposure of Ni nanoparticles after gas-induction, while the CeOx overlayer was partially reconstrued to yield more oxygen vacancies, which could enhance tracking Ni nanoparticles. Undoubtedly, Gas-induced effects altered the strong SMSI between Ni nanoparticles and the CeO2 support. This easy-to-run gas-induction method may make it possible to retroactively modulate the SMSI state to improve the performance of heterogenous catalysis, especially applied for syngas conversion.