CO_2 Adsorption Testing on Fly Ash Derived Cancrinite-type Zeolite and its Amine-Functionalized Derivatives

摘要

Fly ash was converted to a Cancrinite-type zeolite and then functionalized with various amines to investigate its ability to adsorb CO2. Fly ash was first subjected to thermal-alkaline treatment followed by hydrothermal treatment to remove unburned carbon and transform it into a cancrinite-type zeolite before being functionalized with either 3-aminopropyltriethoxysilane (APTES), diethanolamine (DEA), or monoethanolamine (MEA). The resulting Cancrinite and its functionalized products were characterized by various techniques to confirm the success of fly ash to Cancrinite transformation and functionalization method. Cancrinite has significant improvement in surface area (77.7 m(2) g(-1)) in comparison with original fly ash (11.2 m(2) g(-1)), but its CO2 adsorption is very poor, about 6.6 mg g(-1). Amine functionalization caused a reduction in the surface area and porosity of the fly ash Cancrinite, however, it enhanced the CO2 adsorption significantly. While the sorbents impregnated with DEA and MEA had higher CO2 adsorption capacities (49 and 84 mg CO2/g adsorbent respectively) than the sorbent grafted with APTES (24 mg CO2/g adsorbent), the grafted sorbent was more stable over multiple adsorption-desorption cycles. This study demonstrated that fly ash-derived Cancrinite-type zeolite has low CO2 adsorption in spite of its high surface area, however, its CO2 adsorption can be improved by amine-functionalization. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38: 77-88, 2019