Role of perovskites phase in Ni-based catalysts for low temperature CO2 methanation.

CO 2 methanation is considered as a promising reaction in the context of mitigating climate change by reducing CO 2 emissions and providing a renewable source of methane fuel. The CeNiO 3 and LaNiO 3 perovskite catalysts were synthesized using the sol-gel method. The effect of perovskite structure on the catalytic activity was studied. The results were compared with Ce-supported and La-supported Ni catalysts (Ni/CeO 2 & Ni/La 2 O 3). Different methods including XRD, N 2 adsorption-desorption, H 2 -TPR, FE-SEM, and CO 2 -TPD, were employed for the characterization of the catalysts. The perovskite catalysts are more active than the corresponding supported catalysts. Among all prepared catalysts CeNiO 3 perovskite catalyst showed highest activity 80% conversion and 98% selectivity at 300 °C. Weak basicity, high active metal reducibility and the synergy between Ni and Ce due to perovskite structure are the responsible factors for high activity of CeNiO 3 catalyst. The CeNiO 3 catalyst showed excellent stability for CO 2 methanation during 24 h of time on study with different GHSVs. The effect of calcination temperature was also studied on CeNiO 3 catalyst at 650, 750 and 850 °C temperatures. Raman spectra concluded that the oxygen vacancy sites increased with rise of calcination temperature from 650 to 750 °C and decreased with further increase in temperature. The CeNiO 3 calcined at 750 °C (CeNiO 3 -750) showed highest activity among all other catalysts. The increased activity is due to increased oxygen vacancies which ensures that Ni nanoparticles are highly dispersed. [Display omitted] • CeNiO 3 & LaNiO 3 perovskites were prepared successfully by sol-gel method. • Ni/CeO 2 & Ni/La 2 O 3 catalysts prepared by wet impregnation method for comparison studies. • CeNiO 3 perovskite showed the highest activity for CO 2 methanation at 300 °C. • The effect of calcination temperature of CeNiO 3 on CO 2 methanation was examined. • Rising calcination temperature from 750 to 850 °C lowered CeNiO 3 oxygen vacancies. [ABSTRACT FROM AUTHOR]