Large-scale synthesis of ZIF-67 and highly efficient carbon capture using a ZIF-67/glycol-2-methylimidazole slurry

New approaches and materials for inexpensive carbon capture are important areas of research. Herein, we report a new material (i.e., zeolitic imidazolate framework-67 (ZIF-67)/glycol-2-methylimidazole (mIm) slurry) that can be used to capture CO2 similar to a liquid absorbent, and ZIF-67 was synthesized on a pilot scale. This flowable slurry was formed by suspending ZIF-67 in a glycol-mIm solution. The results from the gas--slurry equilibrium experiments indicate that this method provides a more efficient approach for the low cost capture of CO2 compared to conventional technologies. The selectivities for CO2/H-2, CO2/N-2, and CO2/CH4 were 1409, 723, and 222, respectively. The apparent solubility of CO2 in the slurry was 1.3 mol L-1, and the sorption enthalpy was only -33 kJ mol(-1) at 1 bar and 303.2 K. To simulate an actual separation process for carbon capture using the ZIF-67/glycol-mIm slurry, a series of column breakthrough tests were performed in a stainless steel bubbling column to investigate the influence of temperature, ZIF-67 mass fraction in the slurry, feed gas flow rate, and composition. The slurry was completely regenerated via helium purging and heating at 323-343 K. The CO2 capture ability of the regenerated slurry was the same as that of the fresh slurry, even after 10 adsorption/desorption cycles. (C) 2015 Elsevier Ltd. All rights reserved.