Enhancement of CO2 adsorption and amine efficiency of titania modified by moderate loading of diethylenetriamine

High-surface-area titanium oxides synthesized using an octylamine template were modified with diethylenetriamine (DETA) by a wet impregnation method for CO2 adsorption. These new composite sorbents were characterized by powder X-ray diffraction, transmission electron microscope, nitrogen adsorption, Fourier transform infrared spectroscopy and thermogravimetric analysis. CO2 capture performances of the adsorbents were tested in a fixed-bed reactor equipped with an on-line mass spectrometer. Experimental results revealed that titania with 30 wt% DETA loading exhibited a high CO2 adsorption capacity of 2.30 mmol g−1 under the conditions of 10.0% (v/v) CO2 in N2 at 75 °C, which is higher than analogue DETA impregnated SBA-15, and the recently reported DETA-impregnated materials. The high adsorption capacity is possibly due to the synergy between the guest DETA and the porous TiO2 supports in the adsorption of CO2. It was also found that at low temperatures, adsorbents with moderate DETA contents are more capable than their higher-loaded counterparts, possibly due to the increased dispersion of amine sites and the strong and productive interactions between the DETA and surface of Ti oxide. Cyclic CO2 adsorption–desorption tests demonstrated that with moderate amine loading, the titania-based sorbent is regenerable and stable.