K2CO3-Modified Potassium Feldspar for CO2 Capture from Post-combustion Flue Gas

Capturing CO2 from post-combustion flue gas is one of the major solutions to CO2 abatement in global warming and climate change. Potassium-based solid sorbents are confirmed as promising means for this purpose. To dispose of the substantive flue gas, the CO2 capture process should be cost-effective. In this work, a novel K2CO3/PF sorbent was prepared by impregnation of potassium carbonate (K2CO3) on potassium feldspar (PP). The synthesized sample was characterized by X-ray fluorescence (XRF), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The CO2 sorption behaviors of K2CO3/PF were evaluated in a fixed-bed reactor in simulated flue gas composition of 60 degrees C, 5% CO2, and 10% H2O. The sorbent regeneration behaviors were also investigated in a N-2 atmosphere at 550 degrees C with a ramping rate of 10 degrees C/min. Further insights were focused on the reaction pathway and multiple cycle behaviors of the sorbent in 10 CO2 sorption desorption tests. The CO2 sorption capacity of K2CO3/PF is calculated as 1.74 mmol of CO2/g. The reaction pathways are revealed as that NaAlSi(3)0(8) and KAlSi3O8 in the support can be converted into NaAlCO3(OH)(2), Al-2(Si2O8)(OH)(4), NaHCO3, and KHCO3 in a humid CO2 atmosphere. The carbonation reaction of K2CO3 to form KHCO3 also contributes considerably to the whole CO2 sorption process. The sorbent regeneration process consists of three steps as the desorption of adsorbed CO2 at 55 degrees C, the decompositions of NaHCO3 and KHCO3 at 130 degrees C, and the decompositions of NaAlCO3(OH)(2) and Al-2(Si2O8)(OH)(4) at 550 degrees C. Besides, the desired sorbent presents excellent regenerability and stability during 10 cyclic CO2 sorption desorption tests. Considering the high CO2 working capacity, long-term stability, low cost of the supporting materials, and recycling of waste resources, K2CO3/PF can be considered as a new option for flue gas treatment.