Synthesis of amine grafted Cu-BTC and its application in regenerable adsorption of ultra-low concentration methyl mercaptan

Abstract

Purification of volatile sulfur compounds is a hot topic since these malodorous gases with low odor thresholds are generated in both community and industry. Adsorption is an effective method, but adsorbent regeneration is usually difficult because of the strong bond between adsorbent and malodorous gases. In this work, an amine-grafted metal–organic framework was synthesized and applied in cyclic adsorption of ultra-low concentration methyl mercaptan (MM). As a result, MM was effectively purified to below 50 ppb for 1062 min, resulting in a breakthrough capacity of 84.9 mg/g. In comparison, the breakthrough time and capacity without grafting amine were 777 min and 58.6 mg/g, respectively. After detailed characterizations, Cu2+ site and amine group were both attributed to MM removal. Although Cu2+ site was unregenerable, the amine group was regenerable with a capacity of 17.9–19.4 mg/g since the N-H bond was weak between amine and MM. In addition, competitive gases CO and CO2 only decreased the breakthrough time and capacity by 10%. The main result of this work is in favor of applying a regenerable adsorbent for purification of ultra-low concentration malodorous gas.