<p class="MDPI12titleori1" style="mso-line-height-alt: 14.0pt;"><span style="mso-bidi-font-size: 18.0pt; mso-ligatures: standardcontextual;">Nickel Catalysts Supported on SiO₂-CeO₂ Mixed Oxides for Methane Dry Reforming

Nickel-supported over SiO₂-CeO₂ mixed oxides were investigated as catalysts for syngas production via the dry reforming of methane. The SiO₂-CeO₂ supports were optimized, playing on the preparation method and ceria loading with the aim of stabilizing nickel nanoparticles, enhancing the catalytic performance, and improving the resistance to coke formation under high-temperature reforming conditions. To investigate the effect of support composition, SiO₂-CeO₂ mixed oxides with ceria contents ranging from 5 to 30 wt% were prepared using two synthesis routes: sol-gel and wetness impregnation methods. A nickel loading of 5 wt% was deposited on the resulting supports. The catalysts were characterized by XRD, N₂ physisorption, temperature-programmed reduction, and Raman spectroscopy. Catalytic activity tests were conducted over reduced catalysts in an H₂-He stream at 750 °C, using a feed mixture containing 15 vol% CH₄ and 15 vol% CO₂ in He. The effect of temperature on catalytic performance was evaluated in the range of 450–800 °C. Thermogravimetric, XRD and Raman analyses of spent catalysts were used to assess carbon deposition and the nature of crystalline phases. The results highlight the role of CeO₂ content and preparation method in determining nickel dispersion, reducibility, catalytic performance in DRM, and coke resistance.