Removal of Sulfur Compounds by a Copper-Based Metal Organic Framework under Ambient Conditions

A copper-based metal organic framework (MOF-199) was synthesized by a hydrothermal method and was used to remove hydrogen sulfide, ethyl mercaptan, and dimethyl sulfide. Characterizations of the samples before and after desulfurization were carried out by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption performance of the prepared sample MOF-199 was evaluated by breakthrough experiments in a fixed-bed reactor. Heat treatment was carried out in nitrogen flow to activate the prepared MOFs. The optimum activation temperature was found to be 180 °C. Evaluation results showed that the breakthrough capacity of MOF-199 for hydrogen sulfide removal increased with the working temperature, whereas the capacity for ethyl mercaptan and dimethyl sulfide removal decreased with the temperature. MOF-199 had the highest breakthrough sulfur capacity for dimethyl sulfide removal (8.48 g of sulfur/100 g of MOF-199). The color of the MOF changed during sulfur capture in all cases, indicating a change in the chemical environment of the copper metal site. Interactions between the unsaturated copper sites in MOFs and the sulfur compounds differed because of the steric effect. A strong interaction was apparent during adsorption of ethyl mercaptan and hydrogen sulfide, which resulted in the formation of various amounts of CuS and serious damage to the MOF structure. The relatively weak interaction with dimethyl sulfide originated from electrostatic force and a weak coordination effect, which led to easy recycling and recovery of MOF-199 by thermal regeneration at 180 °C.