Syngas Production via Methane Dry Reforming over Ceria–Magnesia Mixed Oxide-Supported Nickel Catalysts

Abstract

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.

Dry Reforming of Methane over Ni/γ‐MgO Catalysts in a Coaxial Dielectric Barrier Discharge Reactor

“…They were used to identify the crystalline phases present in the catalysts, to verify that the catalysts were prepared correctly for further discussion. As mentioned before, the presence of NiO, MgO, NiO‐MgO, and CeO 2 phases plays an important role for the result of the discussion, such as the formation of the reactions 15–23, which will be discussed further. The XRD pattern of Ni/MgO in Fig.…”

“…Afterward, the precipitate was filtered and washed with deionized water, dried overnight at 80 °C and calcined at 700 °C for 4 h. Ni/MgO (10 wt % Ni) was prepared by impregnating Ni(NO 3 ) 3 ·6H 2 O with MgO powder at room temperature. The suspension was stirred by a magnetic stirrer (100 rpm) for 4 h, dried overnight at 80 °C and calcined at 500 °C for 4 h. The CeO 2 ‐promoted catalyst was prepared by subsequent impregnation of the Ni/MgO catalyst with different concentrations of cerium nitrate (Ce(NO 3 ) 3 ·6H 2 O, 99.99 %) with the same procedure as described above, to obtain various contents of CeO 2 20.…”

“…The good redox properties are due to the very quick reduction of Ce 4+ to Ce 3+ related with the creation of oxygen vacancies. It has the capability of releasing oxygen under a reducing atmosphere and storing oxygen in an oxidizing environment by filling the oxygen vacancies 20.…”

“…In the article by Khajenori et al 18, different CeO 2 weight loadings of 3 %, 5 %, and 7 % were studied, and the Ni/7%CeO 2 /MgO catalyst had exhibited the highest conversion rate for CH 4 and CO 2 . In the article by Al‐Swai et al 20, a Ni/CeO 2 /MgO catalyst with various CeO 2 loadings was investigated for the DRM reaction. These catalysts were used in the thermal catalytic method and every time 100 mg of the catalyst was placed in the reactor.…”

Electromagnetic waves-induced hydrophobic multiwalled carbon nanotubes for enhanced oil recovery

“…With the increase in the demand of crude oil and reduction in oil sources, extracting additional oil is becoming more challenging (Alnarabiji et al 2014a(Alnarabiji et al , b, 2016Shafie et al 2014;Ahmed et al 2018;Adil et al 2018). Lately, nanosized materials have attracted wide attention due to their extraordinary characteristics (Ameen et al 2019;Ghanem et al 2018;Al-Swai et al 2018;Alnarabiji et al 2017Ali et al 2018;Chuah et al 2016;Alqasem et al 2017). Multiwalled carbon nanotube (MWCNT) as a type of nanomaterials has been implanted in enhanced oil recovery (EOR) and achieved remarkably high recovery .…”