Liquid-Liquid Phase-Change Absorption of Hydrogen Sulfide by Superbase 1,8-Diazabicyclo[5.4.0]undec-7-ene and Its Chemical Regeneration

Abstract Here, we developed a novel absorbent for the sustainable capture of hydrogen sulfide (H2S), which is the blend of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-triethylene glycol dimethyl ether (TEGDME)-H2O. The results indicated that the gravimetric absorption capacity was 0.174 g H2S/g lower phase at 101.3 kPa and 15 °C, which was 1.3 times higher than that of widely used aqueous methyldiethanolamine (MDEA) solution under the similar condition. In addition, TEGDME was mainly remained in the upper phase, while H2S, H2O, and DBU were mainly concentrated in the lower phase. Moreover, only around 44 wt% of the total absorbent needed to be delivered to the stripper for desorption, and other portion of absorbent was directly sent to the absorption tower. Most importantly, this absorption system was demonstrated to be a benign medium for absorbent regeneration through the liquid-phase Claus process. Our results suggested that this DBU-TEGDME-H2O blend was promising for the sustainable H2S capture and conversion in industrial applications.