Synthesis and characterization of amine-impregnated mesoporous ceria nanoparticles for carbon dioxide capture

Abstract

Carbon dioxide (CO2) contributes more than 60% towards global warming especially from the fossil-fuel burning activity. Hence, technologies such as carbon capture storage and utilization was introduced. Among the carbon capture technologies, adsorption by porous materials have been used as adsorbent material. Ceria has been chosen in this study. Commercial ceria has several drawbacks such as less porosity and surface area which reduce the availability of CO2 adsorption site. The objective of this study is to prepare a mesoporous ceria nanoparticles (MCN) via hydrothermal and sol-gel methods. 3-aminopropyltrimethoxysilane (APTMS) was used in order to improve the CO2 capture performance. The characterization of all samples were carried out by nitrogen adsorption-desorption isotherm, X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, pyrrole and CO2 adsorbed FTIR spectroscopy. The performance of the samples were tested by CO2 adsorption at pressure range between 6-900 mmHg and 298 K. The preparation parameters were determined via hydrothermal method at calcination temperature of 673 K, pH 9 and ceria/surfactant ratio 2. These parameters were then applied to sol-gel method and the prepared mesoporous adsorbent produced high surface area (76.0 m2 g-1), large pore size (0.100 cm3 g-1), large pore volume (5.3 nm) and high CO2 uptake (213.8 prnol g-1). The adsorbent also shows high thermal stability because it can retain up to 1171 K. The proposed CO2 adsorption mechanism was elucidated from the CO2 adsorbed FTIR spectroscopy. For MCN-2S, CO2 was adsorbed onto oxygen basic, oxygen vacancy and hydroxyl site on MCN which formed monodentate, bidentate, polydentate and hydrogen carbonate. In addition to these carbonate species, the adsorption of CO2 on APTMS/MCN-2S also occurred through the formation of carbamate species. Low CO2 adsorbed on the APTMS/MCN-2S might be due to the utilization of available oxygen basic sites by APTMS molecules. This study exhibited that MCN adsorbent prepared by sol-gel method showed a potential to be applied at industrial scale due to the rapid preparation method, high thermal stability and high CO2 uptake capacity.