Abdulaziz S. Bentalib

Dry reforming of methane (DRM) is a viable strategy for converting two potent greenhouse gases, CH ₄ and CO ₂ , into synthesis gas (H ₂ and CO), which serves as a precursor for methanol, hydrogen, and Fischer–Tropsch fuels. However, catalyst deactivation due to carbon deposition and sintering remains a major challenge. This study examines Ni/γ-Al ₂ O ₃ catalysts individually promoted with Rh, La, Sm, or Au to evaluate their role in the DRM for syngas production. Detailed characterizations (BET, UV–Vis, TGA, SEM, TEM, XRD, XPS, and cyclic TPR-TPD-TPR) revealed that Rh and La improved Ni dispersion and reducibility. Rh-promoted catalysts showed the best catalytic performance, stability, and the least carbon accumulation, as confirmed by catalyst activity studies, CHN, TGA, and TPR data. Process optimization via central composite design predicted 98% CH ₄ and 97% CO ₂ conversion at 828.5 °C and an H ₂ /CO ratio of 1.038, which was validated by experimental runs performed under these conditions depicting very good agreement with the results predicted by the model.

In the race for industrialization and urbanization, the concentration of greenhouse gases like CO₂ and CH₄ is growing rapidly and ultimately resulting in global warming. An Ni-based catalyst over MgO support (Ni/MgO) offers a catalytic method for the conversion of these gases into hydrogen and carbon monoxide through the dry reforming of methane (DRM) reaction. In the current research work, 1–4 wt% strontium is investigated as a cheap promoter over a 5Ni/MgO catalyst to modify the reducibility and basicity for the goal of excelling the H₂ yield and H₂/CO ratio through the DRM reaction. The fine catalytic activities’ correlations with characterization results (like X-ray diffraction, surface area porosity, photoelectron–Raman–infrared spectroscopy, and temperature-programmed reduction/desorption (TPR/TPD)) are established. The 5Ni/MgO catalyst with a 3 wt.% Sr loading attained the highest concentration of stable active sites and the maximum population of very strong basic sites. 5Ni3Sr/MgO surpassed 53% H₂ yield (H₂/CO ~0.8) at 700 °C and 85% H₂ yield (H₂/CO ratio ~0.9) at 800 °C. These outcomes demonstrate the catalyst’s effectiveness and affordability. Higher Sr loading (>3 wt%) resulted in a weaker metal–support contact, the production of free NiO, and a lower level of catalytic activity for the DRM reaction. The practical and cheap 5Ni3Sr/MgO catalyst is scalable in industries to achieve hydrogen energy goals while mitigating greenhouse gas concentrations.

This study explores the impact of scandium (Sc) as a promoter on the catalytic performance of 4Ni/MCM-41 catalysts for the partial oxidation of methane (POM). 4Ni+Sc/MCM-41 catalysts were synthesized with varying Sc loadings of 0, 0.2, 0.4, 0.6, and 0.8 wt.%. These catalysts were characterized using several techniques, including N₂ physisorption, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Raman spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). All catalysts exhibited a mesoporous structure characterized by narrow slit-shaped pores. Among them, the 4Ni+0.2Sc/MCM-41 catalyst showed the most consistent pore size distribution. The addition of Sc (scandium) facilitated the formation of strongly interacting nickel species, which enhanced the initial catalytic activity. However, a trade-off was observed between initial activity and long-term stability. The optimal Sc loading was determined to be 0.2 wt.%. This catalyst achieved the highest methane conversion rate of 63.9%, a hydrogen yield of 60%, and an H₂/CO ratio of 2.7 while also demonstrating superior stability during extended operation. The 4Ni+0.2Sc/MCM-41 catalyst showed only a 7% weight loss in the thermogravimetric analysis (TGA), which shows that it will stay stable even after being used for a long time. The improved performance of the Sc-promoted catalysts is attributable to the increased availability of active sites, enhanced stability, and better dispersion of nickel. These efforts aim to create more sustainable and efficient methods for hydrogen production, minimizing the negative effects associated with traditional processes. By advancing these technologies, we can further support the transition to a cleaner energy future.

Syngas is produced through the carbon dioxide reforming of methane. The traditional nickel-based catalysts are substantially destroyed by carbon deposition. The reforming reaction was conducted in a tubular microreactor at 700 °C using bimetallic Ni catalysts supported over 37% Al₂O₃ and 63% MgO mixtures. The impregnation process formed the catalysts, which were subsequently examined by N₂-physisorption, XRD, H₂-TPR, TGA, and Raman spectroscopy. The 2.5Ni+2.5Co/37%Al₂O₃+63%MgO bimetallic catalyst, which displayed 72% and 76% conversions of CH₄ and CO₂ over the course of a seven-hour procedure, was discovered to be the most active in DRM. The bimetallic catalyst with the largest weight loss in TGA, 2.5Ni+2.5Fe-MG63, had a loss of 61.3%, a difference of 26% and 21% in the activity performance of CH₄ and CO₂, respectively, of the tested bimetallic Ni catalysts was recorded. The long-time of 30 h on-stream CH₄ and CO₂ conversion reactions for 2.5Ni+2.5Co-MG63 and 2.5Ni+2.5Ce-MG63 catalysts showed the catalysts’ high stability. The TPO analysis for the 2.5Ni+2.5Cs-MG63 catalyst showed a peak at 650 °C, attributed to the oxidation of the filamentous carbon, whereas the TPO analysis for the 2.5Ni+2.5Co-MG63 catalyst depicted a peak at 540 °C, ascribed to the presence of amorphous/graphite carbon.

The dry reforming of methane is a highly popular procedure since it can transform two of the most abundant greenhouse gases, methane and carbon dioxide, into useful syngases that can be further processed into valuable chemicals. To successfully achieve this conversion for the effective production of syngas, an optimal catalyst with advantageous physicochemical features must be developed. In this study, a variety of Ni-based catalysts supported by zirconia alumina (5Ni-10Zr + Al) were prepared by using the impregnation approach. Different loadings of Fe promoter were used, and the performances of the resulting catalysts in terms of activity and stability were investigated. The catalyst used in this study had an active metal component made of 5% Ni and x% Fe supported on 10ZrO₂ + Al₂O₃, where x = (1, 2, 3, and 4). The physicochemical characteristics of both freshly calcined and used catalysts were studied using a range of characterization techniques, such as: N₂ adsorption–desorption isotherms, XRD, H₂-TPR, Raman spectroscopy, TGA, and TEM. An investigation of the effects of the Fe promoter on the catalytic activity of the catalyst (5Ni + xFe-10Zr + Al) was conducted. Amongst the studied catalysts, the 5Ni + 3Fe-10Zr + Al catalyst showed the best catalytic activity with CH₄ and CO₂ conversions of 87% and 90%, respectively, and had an H₂/CO ratio of 0.98.

Flow-electrode capacitive deionization (FCDI) offers an electrochemical, energy-efficient technique for water desalination. In this work, we report the study of carbon-based FCDI, which consists of one desalination chamber and one salination chamber and applies a carbon nanomaterials-based flow electrode that circulates between the cell anode and cathode, to achieve a fast, continuous desalination process. Five different carbon nanomaterials were used for preparing the flow electrode and were studied for the desalination performance, with properties including average salt removal rate (ASRR), salt removal efficiency (SRE), energy consumption (EC) and charge efficiency (CE) being quantitatively determined for comparation. Different FCDI parameters, including carbon concentration and flow rate of the flow electrode and cell voltage, were investigated to examine the influences on the desalination. Long-term operation of the carbon-based FCDI was evaluated using the optimal results found in the conditions of 1.5 M concentration, 1.5 V cell voltage, and 20 mL min⁻¹ flow rate of electrode and water streams. The results showed an ASRR of 63.7 µg cm⁻² min⁻¹, EC of 162 kJ mol⁻¹, and CE of 89.3%. The research findings validate a good efficiency of this new carbon-based FCDI technology in continuous water desalination and suggest its good potential for real, long-term application.