Yolk–Satellite–Shell Structured Ni–Yolk@Ni@SiO₂ Nanocomposite: Superb Catalyst toward Methane CO₂ Reforming Reaction

Abstract

The CO 2 (dry) reforming of methane (DRM) reaction is an environmentally benign process to convert two major greenhouse gases into synthesis gas for chemical and fuel production. A great challenge for this process involves developing catalysts with high carbon resistance abilities. Herein we synthesize, for the first time, a yolk−satellite−shell structured Ni−yolk@Ni@SiO 2 nanocomposite for the DRM reaction by varying the shell thickness of Ni@SiO 2 core shell nanoparticles. The formation of Ni−yolk@Ni@SiO 2 is proved to be shell thickness dependent. Compared with Ni@SiO 2 , Ni− yolk@Ni@SiO 2 with 11.2 nm silica shell thickness shows stable and near equilibrium conversion for CH 4 and CO 2 for 90 h at 800 °C with negligible carbon deposition. The dual effects of formation of small satellite Ni particles due to strong Ni−SiO 2 interactions and yolk shell structures contribute to its high activity and stability. These findings shed light on the design of other metal yolk silica shell nanocomposites to be utilized in renewable energy transfer processes such as DRM reactions driven by solar energy.

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

“…Accordingly, minimal amount of carbon during DRM was observed on Ni/Al 2 O 3 catalysts when the average particle size of nickel was smaller than 7-10 nm [13] [14]. It is quite difficult to maintain the small average particle size under reaction conditions, but it can be achieved by special preparation methods such as decomposition of nickel precursor by dielectric-barrier discharge plasma over silica [15], molecular layer deposition of porous alumina onto the surface of the catalyst [16] or by preparing porous silica shell around nickel nanoparticles [17].…”

Ni/CeO2–Al2O3 catalysts for the dry reforming of methane: The effect of CeAlO3 content and nickel crystallite size on catalytic activity and coke resistance

“…The Ni particle size has a strong effect on the carbon tolerance of the catalyst, and generally, particles smaller than 5 nm have low catalytic activity towards the C H cracking [11,18,19]. Therefore, the stabilization of small Ni nanoparticles at high temperatures is a promising way for the lifetime increase [20,21]. However, together with the properties of the active metal sites, the support choosing is of great importance in designing high-performance catalysts.…”

CeO2-encapsulated noble metal nanocatalysts: enhanced activity and stability for catalytic application

“…metal NPs into highly stable porous inorganic nanostructures (for example, CeO 2 , 24-26 TiO 2 , 27-34 SiO 2 , [35][36][37][38][39] ZrO 2 40,41 ) and encapsulating noble metal NPs within metal oxides to form core-shell or yolk-shell nanostructures are common strategies. Three requirements must be satisfied simultaneously: (1) the sheath must maintain its chemical inertness in the specific working environment; (2) mass transformation must be avoided during the long-term synthetic and catalytic process, especially under high-temperature treatment; (3) after heat treatment, the active sites should maintain their original particle size, shape and catalytic activities.…”