Three-Dimensionally Ordered Macroporous SiO₂ Encapsulated Ni Catalysts with Robust Coke Resistance for Dry Reforming of Methane

Three-dimensionally ordered macroporous SiO 2 (3DOM-SiO 2 ) encapsulated Ni catalyst (designated as Ni@3DOM-SiO 2 ) was prepared by an ammonia evaporation method for the catalytic dry reforming of methane (DRM). The catalyst exhibits higher catalytic activity and better coke resistance property in comparison with Ni/3DOM-SiO 2 and Ni/SiO 2, which were prepared by a conventional impregnation method with 3DOM and commercial SiO 2 as the supports. Characterization results reveal that the Ni nanoparticles in the Ni@3DOM-SiO 2 catalyst are highly dispersed, forming strong metal–support interaction. These unique properties result in decreased temperature for activating both CH 4 and CO 2, as well as excellent resistance toward metal sintering and coke deposition. However, Ni/3DOM-SiO 2 and Ni/SiO 2 deliver higher catalytic activity for CH 4 cracking, leading to coke formation and catalyst deactivation. A reaction mechanism is proposed based on in situ diffuse reflectance infrared Fourier transform results. It is shown that surface –OH groups play crucial roles in CO 2 activation and conversion, thus minimizing coke formation.