CO₂ methanation presents an intriguing avenue for utilizing carbon dioxide and generating methane as synthetic natural gas. Both reducibility and basicity of catalysts play a major role in catalytic performances improvement.

Rising greenhouse gas concentrations are causing climatic change that threatens ecosystem sustainability. This study investigated the impact of silica incorporation into alumina-supported nickel catalysts for the partial oxidation of methane (POM), a crucial process for syngas production. The investigation also focuses on the impact of using different calcination temperatures. The catalysts were synthesized using the impregnation method and structurally characterized with BET, TPR, FTIR, UV, XRD, TGA, Raman, and TEM analysis techniques. These characterization techniques revealed that increasing the silica content reduced the surface area and weakened the interaction between nickel and the support. The calcination temperature significantly influenced catalyst properties, affecting pore structure, nickel reducibility, and the formation of nickel aluminates and silicates. Activity tests of synthesized catalysts were performed in a packed-bed reactor at 600 °C with a 24 mL/min gas flow rate. The catalyst composition of 5Ni/10Si + 90Al demonstrated the highest activity, achieving optimal performance at lower calcination temperatures. This catalyst generates a greater concentration of active sites, primarily due to nickel oxide (NiO), which creates these sites through both mild and strong interactions. The degree of graphitization is notably lowest for the 5Ni/10Si + 90Al composition. This catalyst achieved an impressive hydrogen yield of approximately 54%, with an H₂/CO ratio of 3.4 over a streaming period of up to 240 min. When the silica loading exceeds 10 wt.%, the interaction between the metal and the support weakens, resulting in a significant decrease in surface area and, subsequently, lower catalytic activity. The 5Ni/10Si + 90Al catalyst, which was prepared with calcination temperatures above 500 °C, has very few active sites during the Partial Oxidation of Methane (POM) reaction at a reaction temperature of 600 °C. This catalyst also exhibits a high degree of crystallinity, which leads to reduced exposure of the active sites. As a result, incorporating higher weight percentages of silica into the 5Ni/xSi + (100 − x) Al catalysts results in decreased activity. When the silica loading exceeds 10 wt.%, the interaction between the metal and the support weakens, resulting in a significant decrease in surface area and, subsequently, lower catalytic activity. The 5Ni/10Si + 90Al catalyst, which was prepared with calcination temperatures above 500 °C, has very few active sites during the POM reaction at a reaction temperature of 600 °C. This catalyst also exhibits a high degree of crystallinity, which leads to reduced exposure of the active sites. As a result, incorporating higher wt.% of silica into the 5Ni/xSi + (100 − x) Al catalysts results in decreased activity. These findings highlight the complex interplay between silica content, calcination temperature, and catalyst properties, significantly influencing catalytic performance in POM.

Herein, nanoscale MgAl₂O₄ (MOA), 10%CuO@MgAl₂O₄ (10Cu@MOA), 10%NiO@MgAl₂O₄ (10Ni@MOA), and 10%CoO@MgAl₂O₄ (10Co@MOA) were synthesized employing butylated hydroxytoluene (the food additive BHT) as a capping agent. The SEM images illustrated average sizes of 38.8, 30.0, 40.8, and 32.7 nm for MOA, 10Cu@MOA, 10Ni@MOA, and 10Co@MOA, respectively, and their BET surface area were 84.4, 141.8, 126.7, and 105.3, respectively. Doxycycline DXC removal was studied employing the MOA, 10Cu@MOA, 10Ni@MOA, and 10Co@MOA, which resulted in q_t values of 57.3, 106.1, 97.7, and 73.9 mg g⁻¹, respectively. The pseudo-second order model best described the DXC sorption onto MOA, 10Cu@MOA, 10Ni@MOA, and 10Co@MOA, and both film diffusion models influenced the DXC sorptions onto the sorbents. The DXC sorption onto the 10Cu@MOA fitted the Freundlich model. The thermodynamics implied endothermic-spontaneous DXC sorption onto the10Cu@MOA. The pH study exposed that the DXC removal by 10Cu@MOA was more effective in a mildly acidic medium (pH = 6.0). Furthermore, the 10Cu@MOA effectiveness in treating surface water contaminated by 5.0 and 10.0 mg L⁻¹ DXC was 99.9% and 98.1%, respectively, while it was 94.7% and 92.5% in treating the concentrations above in seawater, respectively. The reusability study showed a 10% reduction in the 10Cu@MOA’s removal efficiency at the fourth cycle, which is encouraging for real-life applications.

Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH₄ and CO₂ into synthetic/energy-important syngas (H₂ and CO). Herein, a molecular sieve (CBV3024E; SiO₂/Al₂O₃ = 30) with ZSM-8-type pore architect, is utilized as the support for the active site of Ni and Ce promoters. Catalysts are characterized by surface area and porosity, X-ray diffraction study, Raman and infrared spectroscopy, thermogravimetry analysis, and temperature-programmed reduction/desorption techniques. A total of 2 wt.% ceria is added over 5Ni/CBV3024E to induce the optimum connectivity of aluminum in the silicate framework. NiO residing in these porous cages are mostly under “prominent interaction with support” which is reduced easily into metallic Ni as the active sites for DRM reactions. The active sites over 5Ni2Ce/CBV3024E remain stable during the DRM reaction and achieve ~58% H₂ yield after 300 min TOS at 42,000 mL/(g_cat.h) GHSV and ~70% H₂ yield after 20 h at 26,000 mL/(g_cat.h) GHSV. The high activity after a longer time stream justifies using CBV3024E molecular sieves as the support and ceria as the promoter for Ni-based catalyst towards the DRM reaction.

This study investigates the effects of samarium (Sm) promotion on the catalytic activity of 5 weight percent Ni catalysts for partial oxidation of methane (POM)-based hydrogen production supported on a Si-Al mixed oxide (10SiO₂+90Al₂O₃) system. Several 5% Ni-based catalysts supported on silica–alumina was used to test the POM at 600 °C. Sm additions ranged from 0 to 2 wt.%. Impregnation was used to create these catalysts, which were then calcined at 500 °C and examined using BET, H₂-TPR, XRD, FTIR, TEM, Raman spectroscopy, and TGA methods. Methane conversion (57.85%) and hydrogen yield (56.89%) were greatly increased with an ideal Sm loading of 1 wt.%, indicating increased catalytic activity and stability. According to catalytic tests, 1 wt.% Sm produced high CH₄ conversion and H₂ production, as well as enhanced stability and resistance to carbon deposition. Nitrogen physisorption demonstrated a progressive decrease in pore volume and surface area with the addition of Sm, while maintaining mesoporosity. At moderate Sm loadings, H₂-TPR and XRD analyses showed changes in crystallinity and increased NiO reducibility. Sm incorporation into the support and its impact on the ordering of carbon species were indicated by FTIR and Raman spectra. The optimal conditions to maximize H₂ yield were successfully identified through optimization of the best catalyst, and there was good agreement between the theoretical predictions (87.563%) and actual results (88.39%). This displays how successfully the optimization approach achieves the intended outcome. Overall, this study demonstrates that the performance and durability of Ni-based catalysts for generating syngas through POM are greatly enhanced by the addition of a moderate amount of Sm, particularly 1 wt.%.