Trifunctional strategy for the design and synthesis of a Ni-CeO2@SiO2 catalyst with remarkable low-temperature sintering and coking resistance for methane dry reforming

Abstract

In this study, a trifunctional strategy was developed to prepare a confined Ni-based catalyst (Ni-CeO2@SiO2) for dry reforming of methane (DRM) of two main greenhouse gases—CO2 and CH4. The Ni-CeO2@SiO2 catalyst was fabricated by utilizing the confinement effect of the SiO2 shell and the synergistic interaction between Ni-Ce and the decoking effect of CeO2. The catalysts were systematically characterized via X-ray diffraction, N2 adsorption/desorption, transmission electron microscopy, energy dispersive X-ray spectroscopy, hydrogen temperature reduction and desorption set by program, oxygen temperature program desorption, Raman spectroscopy, thermogravimetric analysis, and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements to reveal their physicochemical properties and reaction mechanism. The Ni-CeO2@SiO2 catalyst exhibited higher activity and stability than the catalyst synthesized via the traditional impregnation method. In addition, no carbon deposition was detected over Ni-CeO2@SiO2 after a 100 h durability test at 800 °C, and the average particle size of Ni nanoparticles (NPs) in the catalyst increased from 5.01 to 5.77 nm. Remarkably, Ni-CeO2@SiO2 also exhibited superior low-temperature stability; no coke deposition was observed when the catalyst was reacted at 600 °C for 20 h. The high coking and sintering resistance of this confined Ni-based DRM catalyst can be attributed to its trifunctional effect. The trifunctional strategy developed in this study could be used as a guideline to design other high-performance catalysts for CO2 and CH4 dry forming and accelerate their industrialization.