Pentaethylenehexamine loaded SBA-16 for CO2 capture from simulated flue gas

Abstract

Separation of carbon dioxide (CO2) by adsorption can reduce the cost of carbon capture and storage (CCS). Amine-functionalized adsorbents are promising candidates for CO2 capture. In general, amine-functionalized adsorbents for CO2 adsorption are synthesized by an impregnation method. In this work, an amine-functionalized adsorbent was prepared by impregnating Pentaethylenehexamine (PEHA) on mesoporous silica SBA-16. The as-prepared adsorbents were characterized by X-ray Powder Diffraction (XRD), Thermal Gravimetric Analysis (TGA) and nitrogen adsorption/desorption. The results showed that the surface area, pore size and pore volume of the prepared adsorbent decreased with the increase of PEHA loading, while the basic pore structure remained unchanged. CO2 adsorption performance was studied on a Differential Scanning Calorimetry & Thermogravimetric Analysis (DSC–TGA) device and a fixed adsorption column equipped with an on-line Gas Chromatography (GC) device. When the temperature was in the range of 303K to 343K, the adsorption capacity increased with the increase of temperature, but the adsorption capacity decreased at 353K. The adsorption capacity rose from 1.6mmol/g-adsorbent to 2.1mmol/g-adsorbent when the amount of loaded PEHA reached 40wt% (343K). The adsorption capacity is improved by the presence of water vapor in the simulated flue gas. The O2 and NO have little effect on the adsorption process. When the concentration of SO2<100ppm, the adsorption process is unaffected. However, the adsorption process would be affected by the presence of high concentration SO2 (>100ppm). The dynamic adsorption performance was studied by using a fixed adsorption column. The results indicated that the adsorption process maintained a steady adsorption rate of 0.033mmol/min for each adsorption temperature before CO2 adsorption breakthrough. The adsorption capacity maintained almost the same after 20cycles of adsorption/regeneration under simulated flue gas conditions. This work presents a thermally stable adsorbent with relatively high CO2 adsorption capacity, optimum adsorption and regeneration temperatures, as well as favorable CO2 adsorption/desorption performance under simulated flue gas conditions. These properties make the adsorbent suitable for industrial CO2 capture application.