Amine-immobilized HY zeolite for CO2 capture from hot flue gas

Abstract

• Amines were immobilized by HY zeolite by ionic bond showing exceptional thermal stability. • Amine@HY zeolite presented cyclic CO 2 adsorption capacity higher than other grafted amines. • Amine@HY zeolite presented better CO 2 over N 2 selectivity than parent material. • Amine@HY are promising for carbon capture from hot postcombustion flue gases. Solid amine-based adsorbents were widely studied as an alternative to liquid amine for post-combustion CO 2 capture (PCC). However, most of the amine adsorbents suffer from low thermal stability and poor cyclic regenerability at the temperature of hot flue gases. Here we present an amine loaded proton type Y zeolite (HY) where the amines namely monoethanolamine (MEA) and ethylenediamine (ED) are chemical immobilized via ionic bond to the zeolite framework to overcome the amine degradation problem. The MEA and ED of 5%, 10% and 20% (mass) concentration – immobilized zeolites were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and N 2 −196 °C adsorption to confirm the structure integrity, amine functionalization, and surface area, respectively. The determination of the amine loading was given by C, H, N elemental analysis showing that ED has successfully grafted almost twice as many amino groups as MEA within the same solvent concentration. CO 2 adsorption capacity and thermal stability of these samples were measured using thermogravimetric analyser. The adsorption performance was tested at the adsorption temperature of 30, 60 and 90 °C, respectively using pure CO 2 while the desorption was carried out with pure N 2 purge at the same temperature and then followed by elevated temperature at 150 °C. It was found that all the amine@HY have a substantial high selectivity of CO 2 over N 2 . The sample 20% ED@HY has the highest CO 2 adsorption capacity of 1.76 mmol∙g −1 at 90 °C higher than the capacity on parent NaY zeolite (1.45 mmol∙g −1 only). The amine@HY samples presented superior performance in cyclic thermal stability in the condition of the adsorption temperature of 90 °C and the desorption temperature of 150 °C. These findings will foster the design of better adsorbents for CO 2 capture from flue gas in post-combustion power plants.