Enhancement of CO2adsorption and amine efficiency of titania modified by moderate loading of diethylenetriamine

Abstract

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.