Preparation of porous MgO/ZrO2-supported amine-based adsorbents and their application in CO2 capture

Currently, the solid adsorbents with porous structure have been widely applied in CO₂ capture. However, the unmodified MgO-ZrO₂ adsorbents appeared to be low adsorption capacity of CO₂. The solid adsorbent materials were successfully synthesized by loading TEPA onto the pore MgO/ZrO₂ carriers in the paper. The pore structure and surface characteristic of the samples were analyzed by using XRD, BET, FT-IR and SEM. The adsorbent materials exhibited microcrystalline state, and the crystallinity of all samples gradually decreased as the increase of TEPA content. The pore structure analysis indicated that the modification of MgO-ZrO₂ adsorbents with TEPA led to the decrease of the specific surface areas, but the narrow micro-mesopore size distributions ranging from 1.8−12 nm in the adsorbents still were maintained. FT-IR spectrum results further verified the successful loading of TEPA. The adsorption capacity of the adsorbents for CO₂ were tested by using an adsorption apparatus equipped with gas chromatography. The results indicated that when the TEPA loading reached 50%, the sample exhibited the maximum adsorption value for CO₂, reaching 4.07 mmol/g under the operation condition of 75 °C and atmospheric pressure. This result could be assigned to not only the base active sites but also the coexistence of both micropore and mesopore in the adsorbent. After three cycles tests for CO₂ capture, the adsorption value of the sample for CO₂ can also reached 95% of its original adsorption capacity, which verified the excellent cyclic operation stability.