A comparative study of SiO_2, Al₂O_3, and mixed SiO₂-Al₂O₃-supported nickel catalysts for dry reforming of methane: effects of calcination temperature on catalytic performance

Dry reforming of methane (DRM) offers a sustainable approach for the simultaneous utilization of two major greenhouse gases (CH₄ and CO₂) to generate synthesis gas (syngas). In this study, a comparative investigation of Ni catalysts supported on SiO₂ (Si), Al₂O₃ (Al), and mixed SiO₂-Al₂O₃ (3.5Si + Al) was conducted to assess the effect of calcination temperature on catalyst structure–activity relationships. Catalysts were synthesized via wet impregnation and calcined at 600 °C and 800 °C, followed by extensive characterization using N₂ physisorption, XRD, H₂-TPR, CO₂-TPD, TGA, Raman spectroscopy, and TEM to examine their physicochemical properties before and after reaction. Catalytic performance was evaluated by monitoring CH₄ and CO₂ conversions under controlled DRM conditions. The results demonstrated that 5Ni/Si catalysts exhibited weak basicity and unstable active sites, limiting DRM performance irrespective of calcination temperature. In contrast, catalysts supported on Al₂O₃ and mixed SiO₂-Al₂O₃ and calcined at 600 °C showed higher catalytic activity, attributed to stronger metal–support interactions and the formation of stable active sites. Specifically, 5Ni/Al and 5Ni/(3.5Si + Al) catalysts achieved ~ 58% CH₄ conversion and ~ 65–66% CO₂ conversion over 375 min on stream. However, calcination of 5Ni/(3.5Si + Al) at 800 °C resulted in a significant decrease in the number of active sites at 700 °C reduction/reaction temperature, leading to severe loss of catalytic activity. Further analysis of the best catalyst displayed that increasing the reaction temperature from 700 °C to 800 °C positively affected both CH₄ and CO₂ conversions and the H₂/CO ratio while increasing the space velocity made every parameter worse. The stability test at 700 °C showed that it was stable for 20 h. Hence, this work highlights the importance of support composition and thermal treatment in tailoring the structural and catalytic properties of Ni-based catalysts. The findings provide valuable insights for designing efficient, stable catalysts for syngas production via DRM, contributing to greenhouse gas mitigation through carbon utilization technologies.