AS-synthesized mesoporous silica MSU-1 modified with tetraethylenepentamine for CO2 adsorption

Tetraethylenepentamine (TEPA) was incorporated into as-synthesized mesoporous silica MSU-1 with cheap sodium silicate as silica source to create TEPA/MSU-1, an adsorbent having high adsorption capacity for carbon dioxide. The adsorbents were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, thermogravimetry (TG), and Flourier transform infrared (FTIR) spectrometry. The XRD results indicated that the adsorbents preserved the mesostructure of MSU-1 after TEPA was loaded. However, the surface area decreased dramatically, indicating that the pores are occupied by amine. TG patterns showed that the adsorbents are thermally unstable at temperatures above 200 °C. The FTIR results suggested that CO2 interacts with TEPA to form alkalammonium carbamate. CO2 adsorption isotherms measured at different temperatures revealed that the optimal adsorption temperature is 75 °C. Temperature-programmed desorption (TPD) of CO2 showed that the desorption of CO2 achieved maximal desorption rate at about 100 °C, and so is appropriate for thermal swing adsorption of CO2 from flue gas. The adsorption capacity of TEPA/MSU-1 with a different TEPA content was calculated through CO2 breakthrough curves. As a result, 50 wt% of TEPA supported on as-synthesized MSU-1 achieved the highest capacity at 3.87 mmol/g.

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► An adsorbent with tetraethylenepentamine loaded on MSU-1 was made and characterized.
► 50 wt% of TEPA supported on as-synthesized MSU-1 achieved the highest capacity.
► It has an excellent selectivity for CO2/N2 system.
► The optimal adsorption temperature is 75 °C and CO2 is thoroughly released at 100 °C.