Unveiling the promotion effect of ethylenediamine on preparation of Ni/CeO2 catalyst for low-temperature CO2 methanation

Abstract

Cost-effective CO2 conversion to value-added products remains a great challenge until present. Here, we have discovered that the ethylenediamine (EDA) assisted preparation of Ni/CeO2 catalyst remarkably promotes the CO2 methanation performance at low temperatures. The Ni/CeO2-EDA catalyst exhibits a CO2 conversion efficiency of 84% and a CH4 selectivity of 98% at 225 °C, and no visible decline of CO2 conversion is observed even after 70h of continuous reaction. The involvement of EDA is shown to effectively result in a more uniform distribution of Ni species, coupled with a reduction in particle size. In addition, the smaller particle size of Ni results in a rapid dissociative adsorption of hydrogen and H2 spillover. Accordingly, oxygen vacancies on the CeO2 surface are created and adequate H atoms are engendered for CO2 hydrogenation. Furthermore, both the formate and CO pathways occur simultaneously on the Ni/CeO2-EDA catalyst, enhancing the low-temperature methanation activity. Herein, the EDA-assisted strategy provides an effective methodology in terms of well-dispersion and highly active catalysts for low-temperature CO2 methanation.