Nickel/ceria nanorod catalysts for the synthesis of substitute natural gas from CO2: Effect of active phase loading and synthesis condition

CO2 methanation is one of the advantageous processes of carbon capture and utilisation (CCU) technologies to circulate the carbon on Earth, mitigating the release and loss of CO2 into the atmosphere. Herein, a Ni/r-CeO2 catalyst was fabricated using a facile method of impregnating Ni(NO3)2·6H2O on CeO2 nanorods (r-CeO2), synthesised by hydrothermal method at low temperature (130 °C). The influence of Ni active phase content and activation condition on the characteristics and catalytic performances in CO2 methanation were investigated. The physicochemical properties of the synthesised catalyst were studied using several techniques: XRD, EDS, isotherm nitrogen adsorption, SEM, HR-TEM, H2-TPR, CO2-TPD and Raman. Catalytic activity survey and analysis show the excellent performance of Ni/r-CeO2 with a Ni loading of 15 wt% (15NiCe) calcined at 600 °C for 4 h and reduced at 450 °C for 2.5 h. By adjusting the nickel loading on ceria and altering synthesis conditions, it's possible to achieve highly dispersed NiO particles with an optimal size (∼13.9 nm), abundant oxygen vacancies, and the presence of medium-strength basic sites. This leads to improved catalytic activity, resulting in an equilibrium CO2 conversion rate of approximately 90% and 100% selectivity for CH4 at temperatures as low as 325°C. The 15Ni/r-CeO2 catalyst serves as a highly active low-temperature catalyst for CO2 methanation.