Adsorption of CO and CO2 in Large Pore Sized Ag@SiO2 Nanocomposite

In the context of H-2 purification, it is of great interest to find a porous material that will simultaneously adsorb CO and CO2. In this study, Ag@SiO2 nanocomposites were prepared starting from a large pore sized mesoporous matrix. The presence of Ag nanoparticles was highlighted using different techniques. Around 0.4 wt % of nanoparticles were inserted with a mean diameter of around 12 nm. The adsorption properties of both CO2 and CO were studied using microcalorimetry. It was shown that the presence of silver did not affect CO2 uptake in terms of unit surface and only slightly affected the adsorption enthalpy at low coverage. In contrast, compared to the pure silica matrix, the adsorption of carbon monoxide on the Ag@SiO2 nanocomposites is associated with a high adsorption enthalpy at very low coverage (highlighting the strong interaction of CO with the Ag particles) and with an adsorption uptake that is doubled. Finally, by comparing the adsorption properties for both CO2 and CO to the ones determined for other porous adsorbents, the Ag@SiO2 nanocomposite can be considered as an interesting candidate for the adsorption of trace amounts of CO in the presence of CO2. This was confirmed by a last experiment using an industrial CO2/CO gas mixture (80% mo1/20% mol).