Effect of ceria/surfactant molar ratios on the formation of mesoporous ceria nanoparticles and its application in CO2 capture

Abstract

Large quantities of carbon dioxide (CO₂) in a mixture of natural gas/CO₂ can reduce the heating value of the mixture, reducing the thermal efficiency of a gas engine. Therefore, CO₂ should be separated from the natural gas. CO₂ separation through adsorption method has several advantages, such as high energy efficiency, easy operation, low cost, and availability of different adsorbents. There is a need to develop adsorbents with a porous structure. Several reaction parameters influence the synthesis of porous adsorbents, including temperature, solvent, stirring rates, co-surfactant, pH, and metal to surfactant molar ratio. In this study, the effect of varying ceria to surfactant molar ratio on the synthesis of mesoporous ceria nanoparticles (MCNs) was investigated for CO₂ adsorption. Using cetyltrimethylammonium bromide (CTAB) as a surfactant agent, MCNs were prepared by varying ceria to CTAB molar ratio (0.5, 1.0, 1.5, and 2.0) via a simple hydrothermal method. All the MCN samples showed a bimodal mesoporous structure around 18–30 nm with pore sizes of 3.7 nm. Thermogravimetric analysis showed that the MCNs had weight loss of < 5% when heated up to 1173 K, indicating high thermal stability. MCN-1.0 showed the highest CO₂ adsorption at 0.37 mmol/g, followed by MCN-1.5 and MCN-2.0 at 1 bar and 298 K. We believe that this study will expand the knowledge of ceria material properties towards CO₂ adsorption and will be useful in material selection for industrial CO₂ capture.