Impact of Sr Addition on Zirconia-Alumina-Supported Ni Catalyst for COx-Free CH4 Production via CO2 Methanation

• Published in: ACS omega Vol. 9; no. 8; pp. 9309 - 9320
• Main Authors: Abahussain, Abdulaziz A M, Al-Fatesh, Ahmed S, Rajput, Yuvrajsinh B, Osman, Ahmed I, Alreshaidan, Salwa B, Ahmed, Hamid, Fakeeha, Anis H, Al-Awadi, Abdulrhman S, El-Salamony, Radwa A, Kumar, Rawesh
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.02.2024
• ISSN: 2470-1343
• DOI: 10.1021/acsomega.3c08536

Zirconia-alumina-supported Ni (5Ni/10ZrO2+Al2O3) and Sr-promoted 5Ni/10ZrO2+Al2O3 are prepared, tested for carbon dioxide (CO2) methanation at 400 °C, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, surface area and porosity, infrared spectroscopy, and temperature-programmed reduction/desorption techniques. The CO2 methanation is found to depend on the dispersion of Nickel (Ni) sites as well as the extent of stabilization of CO2-interacted species. The Ni active sites are mainly derived from the reduction of 'moderately interacted NiO species'. The dispersion of Ni over 1 wt % Sr-promoted 5Ni/10ZrO2+Al2O3 is 1.38 times that of the unpromoted catalyst, and it attains 72.5% CO2 conversion (against 65% over the unpromoted catalyst). However, increasing strontium (Sr) loading to 2 wt % does not affect the Ni dispersion much, but the concentration of strong basic sites is increased, which achieves 80.6% CO2 conversion. The 5Ni4Sr/10ZrO2+Al2O3 catalyst has the highest density of strong basic sites and the highest concentration of active sites with maximum Ni dispersion. This catalyst displays exceptional performance and achieves approximately 80% CO2 conversion and 70% methane (CH4) yield for up to 25 h on steam. The unique acidic-basic profiles composed of strong basic and moderate acid sites facilitate the sequential hydrogenation of formate species in the COx-free CH4 route.