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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.

Recently, nano-EOR has emerged as a new frontier for improved and enhanced oil recovery (IOR & EOR). Despite their benefits, the nanoparticles tend to agglomerate at reservoir conditions which cause their detachment from the oil/water interface, and are consequently retained rather than transported through a porous medium. Dielectric nanoparticles including ZnO have been proposed to be a good replacement for EOR due to their high melting point and thermal properties. But more importantly, these particles can be polarized under electromagnetic (EM) irradiation, which provides an innovative smart Nano-EOR process denoted as EM-Assisted Nano-EOR. In this study, parameters involved in the oil recovery mechanism under EM waves, such as reducing mobility ratio, lowering interfacial tensions (IFT) and altering wettability were investigated. Two-phase displacement experiments were performed in sandpacks under the water-wet condition at 95°C, with permeability in the range of 265–300 mD. A crude oil from Tapis oil field was employed; while ZnO nanofluids of two different particle sizes (55.7 and 117.1 nm) were prepared using 0.1 wt. % nanoparticles that dispersed into brine (3 wt. % NaCl) along with SDBS as a dispersant. In each flooding scheme, three injection sequential scenarios have been conducted: (i) brine flooding as a secondary process, (ii) surfactant/nano/EM-assisted nano flooding, and (iii) second brine flooding to flush nanoparticles. Compare with surfactant flooding (2% original oil in place/OOIP) as tertiary recovery, nano flooding almost reaches 8.5–10.2% of OOIP. On the other hand, EM-assisted nano flooding provides an incremental oil recovery of approximately 9–10.4% of OOIP. By evaluating the contact angle and interfacial tension, it was established that the degree of IFT reduction plays a governing role in the oil displacement mechanism via nano-EOR, compare to mobility ratio. These results reveal a promising way to employ water-based ZnO nanofluid for enhanced oil recovery purposes at a relatively high reservoir temperature.

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