Mesoporous Cu-SBA-15 with highly ordered porous structure and its excellent CO2 adsorption capacity

Abstract

CuOx loaded mesoporous silicas with highly ordered mesoporous structures (Cu-SBA-15) and different silicon to copper ratios were synthesized by using P123 as a template under mild acidic conditions. XRD and N2 sorption results confirm the well-ordered 2D mesoporous structure with a high specific surface area and a large pore volume. The pore diameter of Cu-SBA-15 increases from 7.9 to 8.5 nm with a concomitant decrease of the specific surface area from 865 to 802 m2/g as the amount of Cu in the silica framework is increased. We also show the introduction of Cu in the SBA-15 makes a significant change in the final morphology, which changes from rod to curve shaped morphology when the amount of Cu in the SBA-15 is increased. XRD results confirm the presence of CuO nanoparticles inside the nanochannels of SBA-15. The materials were used as adsorbents for high pressure CO2 adsorption at different temperatures −5, 0, 10 and 25 °C and pressures up to 30 bar. The highest CO2 adsorption of 27.6 mmol/g at −5 °C was achieved for Cu-SBA-15 sample with a nSi/Cu ratio of 5 and was found to be much higher than that of pure SBA-15 silica under similar conditions, illustrating the role of CuOx doping in the SBA-15 framework.