Absorption and Removal Efficiency of Low-Partial-Pressure H2S in a Tetramethylammonium Glycinate Activated N‑Methyldiethanolamine Aqueous Solution

The absorption performance including absorption capacity and loading values of low-partial-pressure H2S in tetramethylammonium glycinate ([N1111]­[Gly]) promoted N-methyldiethanolamine (MDEA) aqueous solution was measured. The apparent absorption rate was calculated from the time-dependent absorption capacity. The effects of absorbent composition, temperature, and H2S partial pressure on absorption capacity and apparent absorption rate were demonstrated. The H2S removal efficiency was verified in a tray tower using the [N1111]­[Gly]–MDEA aqueous solution as an absorbent, and the results show that the removal efficiency can reach 100%, which met the requirement of the first degree of Chinese cleaner production standard (coking industry, HJ/T 126-2003, I, H2S ≤ 0.2 g/m3). Compared with the traditional amine-based absorbents like MDEA–monoethanolamine aqueous solution, the [N1111]­[Gly]-promoted MDEA aqueous solution has a higher absorption capacity and a higher absorption rate for H2S. Moreover, when the mass fraction of MDEA reaches up to 50%, the removal efficiency in the tray tower can still reach 100%. The decrease of the water content in the absorbent can greatly reduce the energy cost of the regeneration of rich solution and the cooling of poor solution. Therefore, the new absorbent proposed in this work has good commercial application potential in the field of desulfurization of the coke oven gas.