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

Abstract

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.