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.

In recent decades, rising anthropogenic greenhouse gas emissions (mainly CO2 and CH4 ) have increased alarm due to escalating effects of global warming. The dry carbon dioxide reforming of methane (DRM) reaction is a sustainable way to utilize these notorious greenhouse gases. This paper presents a review of recent progress in the development of nickel-based catalysts for the DRM reaction. The enviable low cost and wide availability of nickel compared with noble metals is the main reason for persistent research efforts in optimizing the synthesis of nickel-based catalysts. Important catalyst features for the rational design of a coke-resistant nickel-based nanocatalyst for the DRM reaction are also discussed. In addition, several innovative developments based on salient features for the stabilization of nickel nanocatalysts through various means (which include functionalization with precursors, synthesis by plasma treatment, stabilization/confinement on mesoporous/microporous/carbon supports, and the formation of metal oxides) are highlighted. The final part of this review covers major issues and proposed improvement strategies pertaining to the rational design of nickel-based catalysts with high activity and stability for the DRM reaction.

The effect of Na loading on the water–gas shift (WGS) activity of Ni/xNa/CeO2 (with x = 0, 0.5, 1, 2, 5, and 10 wt %) catalysts has been investigated. Ni/2Na/CeO2 exhibited the highest performance in terms of WGS activity and methane suppression. Through H2-TPR and XRD, the solubility limit of Na+ in CeO2 was found to be 2 wt %. At low loadings of Na (0.5 to 2 wt %), Na+ was incorporated into the CeO2 lattice, generating a lattice strain and activating the lattice O2, thereby increasing the reducibility of the catalyst. However, beyond the solubility limit of 2 wt %, Na deposited on the CeO2 surface, retarding the reducibility of the catalyst. XPS spectra reveal greater surface concentration of adsorbed oxygen species with the introduction of Na. This can be attributed to the generation of more oxide vacancies for oxygen adsorption due to Na substitution into the ceria lattice. By in situ DRIFTS, methanation was found to be inhibited by the interaction between Na and Ni, leading to the absence of subcarbonyl species which are responsible for this undesirable side reaction.

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