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Dry reforming of methane (DRM) is becoming an appealing research topic because of the urgent need to minimize global warming and the demand for alternative energy resources. However, DRM commercialization and industrial scale application are limited by the deactivation of the applied catalysts. In this work, Ni-based catalysts supported on CeO 2 −MgO mixed oxides (0−20% CeO 2 molar content) were prepared and employed in DRM. The support was synthesized via a coprecipitation method followed by impregnation of Ni metal. The catalysts prepared were characterized by X-ray diffraction, Brunauer−Emmett−Teller (BET) analysis, temperature-programmed reduction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy (FESEM) techniques. The catalytic performance of the catalysts was evaluated in a fixed-bed continuous reactor with an equimolar (CH 4 /CO 2 ) ratio at 1073 K. The addition of CeO 2 , as a promoter to the support, altered the interaction between Ni and MgO and modulated the properties of the catalysts toward an excellent activity performance and multiwalled carbon nanotubes (MWCNTs) production. CeO 2 significantly enhanced the BET surface area, promoted Ni dispersion, and improved the reducibility of the catalyst. Among the obtained catalysts, Ni/15%CeO 2 −MgO achieved the maximum conversion of both CO 2 (95.2%) and CH 4 (93.7%) without significant deactivation during the reaction. The superior catalytic performance of the aforementioned catalyst is due to the presence of a high quantity of active Ni sites and the high Ce 3+ /Ce 4+ ratio that promoted the formation of oxygen vacancies. With the aid of temperature-programmed oxidation, FESEM, transmission electron microscopy, and Raman spectroscopy analysis, it was found that the amorphous carbon encapsulated the active sites of the catalysts, in the absence of Ce, which suppressed the syngas production significantly. The introduction of Ce not only decreased the deposited carbon but also changed the type of the later to MWCNTs, which had positive effects on the activity of the catalyst.

The increase in the synthesis of biodiesel has also contributed to a surplus of crude glycerol, which is a significant bottleneck throughout the supply chain of biodiesel and has produced new problems for its sustainable usage. While there is a broad variety of possible uses of crude glycerol, it is restricted by its purity level, affecting its physical, chemical, and biological properties. In this Review, we look at optimization of the biodiesel production process and significant rise in the use of glycerol. The conversion of impure glycerol into pure glycerol and potential application of glycerol in value-added products are emerging topics. The acetalization of glycerol with acetone in the presence of various heterogeneous catalysts and production of solketala valuable green productare discussed. The research studies described herein mainly focus on innovative and emerging technology for sustainable solketal production, as well as the impact of reaction parameters, removal of water, and catalytic activity in both batch and continuous processes. Globally, the potential prospects for the world market should be determined by the availability and demand for glycerol for use in new industries. This paper illustrates the present scenario for the development of glycerol from the biodiesel sector, the world demand, and future emerging markets for glycerol as a commodity chemical.

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