Properties of yolk–shell structured Ni@SiO2 nanocatalyst and its catalytic performance in carbon dioxide reforming of methane to syngas

• Ni@SiO2-yolk–shell behaved remarkably stable in CRM at high temperature.
• Ni@SiO2-yolk–shell could reduce sintering of Ni particles and carbon deposition.
• The hollow space enables the Ni particles to reshape to form filamentous carbon.
• The formation of filamentous carbon would not influence greatly on the stability.

Ni@SiO2-yolk–shell catalyst was prepared by the method of etching Ni@SiO2-core–shell with hydrochloric acid, while the core–shell catalyst was prepared by the stöber method. In comparison, Ni–SiO2–AE (without yolk–shell structure) was used to denote the catalyst prepared by the similar method as Ni@SiO2-yolk–shell but without fully encapsulation of Ni particles by SiO2. The catalytic performances of these three catalysts were investigated in carbon dioxide reforming of methane to syngas (CRM). The reaction was conducted under different conditions by varying GHSVs of reactants and reaction temperatures to further test the stability of the catalysts. The properties of the as-prepared and spent Ni@SiO2-yolk–shell, Ni@SiO2-core–shell and Ni–SiO2–AE catalysts were characterized by TEM/HRTEM, XRD, TG-DSC to measure the morphology, crystallinity and carbon deposition, etc. It was found that compared to Ni@SiO2-core–shell and Ni–SiO2–AE catalysts, Ni@SiO2-yolk–shell catalyst behaved remarkably stable performance at the temperature up to 1073 K, and the specific structure and carbon deposition-resisted behavior of the Ni@SiO2-yolk–shell catalyst may help to maintain the stability during the reaction.

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