Experimental study on adsorption removal of SO2 in flue gas by defective UiO-66

Abstract

Metal-organic frameworks (MOFs) with a high specific surface area, an adjustable pore structure, and functionalized pore environment have a broad application prospect in gas adsorption and separation. In this work, a series of defective UiO-66 (UiO-66-monocarboxylic acid) samples were prepared by adding different monocarboxylic acids during the synthesis of UiO-66. UiO-66-monocarboxylic acid samples (UiO-66-formic acid, UiO-66-acetic acid, UiO-66-benzoic acid, UiO-66-acrylic acid, and UiO-66-cyanoacetic acid) had a high specific surface area (1200–1400 m2/g) and a good thermal stability (560 °C). In the desulfurization experiment of simulated flue gas (SO2/CO2/O2/N2, 0.3/10.0/5.5/84.2 vol%), the breakthrough time of UiO-66-cyanoacetic acid for SO2 was higher (194 min/g), and the selectivity of SO2/CO2 reached 33.8. Through optimizing the moles of cyanoacetic acid added, the breakthrough time of SO2 on 18-UiO-66-cyanoacetic acid increased to 251 min/g. At a pressure of 1.0 bar and a temperature of 298 K, the adsorption capacity of SO2 by 18-UiO-66-cyanoacetic acid reached 762.1 mg/g. In addition, the adsorption behavior of 18-UiO-66-cyanoacetic acid for SO2 was considered as a combination of chemical and physical adsorption, and fractional chemisorption sites was provided by cyanoacetic acid.