Liquid-liquid phase-change absorption of hydrogen sulfide by superbase 1,8-diazabicyclo[5.4.0]undec-7-ene and its chemical regeneration

Highly Efficient Nonaqueous Phase Change Absorbent for H2S Absorption with Low Energy Consumption

“…The peak at 2545 cm −1 is attributed to the stretching vibration peak of S− H, 23 while the broad peak at 2104 cm −1 is ascribed to the stretching vibration peak of N−H + of tertiary amine. 22,23 Similar results were also found in the [DBUH][SH] salt. 36 As a result, the results of both 1 H NMR and FTIR confirm the formation of [DBNH + ][HS − ] in the resultant solution.…”

“…1–9) showed phase change performance after absorbing CO 2 , were adopted in the absorption of H 2 S. The reason why DBN solutions (no. 10–11) were chosen was that DBN showed good performance in the absorption of H 2 S. , Meanwhile, NHD is a typical physical absorbent in the absorption of H 2 S, which is soluble in DBN. In the absorption of H 2 S, the compositions of those absorbents were the same as those used in the absorption of CO 2 in the literature.…”

“…It indicates that all of the 1 H nuclei are deshielded after the protonation of the N atom at position 8. 22,23,34,36 Meanwhile, the 13 C NMR (Figure 4b) spectra indicate that the C6 and C7 atoms undergo more pronounced shifts compared with C3 and C4 atoms, which move from 43.87 and 159.50 ppm to 37.87 and 163.81 ppm, respectively. These changes suggest that the N8 atoms got protonated during the absorption of H 2 S. Similar results were also found in other literature studies.…”

“…14,15 Unfortunately, most of the literature about phase change absorbents focuses on the absorption of CO 2 16−18 and SO 2 . 19−21 Few of them paid attention to that of H 2 S. Xu 22,23 The absorbed H 2 S is concentrated in the lower phase which accounts for less than 50% of the total mass, and the H 2 S loading reached 0.205 g H 2 S•g −1 lower phase and 0.174 g H 2 S• g −1 lower phase for DBN/hexadecane/hexanol solution and DBU/TEGDME/H 2 O solution, respectively. However, the essential regeneration energies were not included in their studies.…”

“…Nonaqueous absorbents, ionic liquids, deep eutectic solvents, and phase change absorbents were investigated in recent years for H 2 S separation. A phase change absorbent is found quite promising due to decreasing the amount of solvent sent to regeneration via phase separation either into liquid–liquid phases or solid–liquid phases. , Unfortunately, most of the literature about phase change absorbents focuses on the absorption of CO 2 − and SO 2 . − Few of them paid attention to that of H 2 S. Xu , et al developed 1,5-diazabicyclo[4.3.0]­non-5-ene (DBN)/hexadecane/hexanol solution and 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU)/triethylene glycol dimethyl ether (TEGDME)/H 2 O solution as liquid–liquid phase change absorbents for H 2 S absorption. The absorbed H 2 S is concentrated in the lower phase which accounts for less than 50% of the total mass, and the H 2 S loading reached 0.205 g H 2 S·g –1 lower phase and 0.174 g H 2 S·g –1 lower phase for DBN/hexadecane/hexanol solution and DBU/TEGDME/H 2 O solution, respectively.…”