Lewis Acid Sites Stabilized Nickel Catalysts for Dry (CO2) Reforming of Methane

摘要

Strong Lewis acid species [Al-F] were synthesized on a series of Al2O3-supported Ni catalysts modified with (0, 1, 5, and 10 wt.%) of KF to investigate the electronic and anchoring effect of [Al-F] on Ni catalysts in terms of catalytic activity, stability, and carbon resistance during dry reforming of methane (DRM) reaction. With the aids of XRD analysis, X-ray photoelectron spectroscopy, H-2 temperature-programmed reduction, and in situ diffuse reflectance infrared Fourier transform spectroscopy analyses, it was found that the activity and stability of KF-modified catalysts in the reaction was directly associated to the presence of [Al-F] sites. The [Al-F] Lewis acid sites not only stabilized the metal Ni from high-temperature sintering after reaction of 200 h through an enhanced metal-support interaction, but also reduced the electron density of Ni metal, which alleviated the fast decomposition of CH4 and subsequent carbon deposition on catalysts. Balancing the rates for CH4 dissociation and carbon removal would be promising steps in the design of active and stable Ni-based catalysts.