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

Abstract

The absorption performance of low-partial-pressure H 2 S in a monoethanolamine (MEA)-activated Nmethyldiethanolamine (MDEA) aqueous solution was investigated. The absorption amount (in mass, g H 2 S/g solutions) and H 2 S loadings (mol H 2 S/(mol MEA + mol MDEA)) were measured, and the apparent absorption rate was determined from the time-dependent absorption capacity. Experimentally, the temperature and partial pressure of H 2 S (P H 2 S ) ranged from 303.2 to 323.2 K and from 300 to 500 Pa, respectively. The mass fractions of MDEA (w MDEA ) and MEA (w MEA ) ranged from 0.30 to 0.50 and from 0 to 0.075, respectively. The temperature, w MDEA , w MEA , and P H 2 S dependencies of the absorption performance were analyzed. It is impressive that the addition of MEA significantly enhanced the absorption amount of H 2 S yet slightly influenced the apparent absorption rate. In addition, a tray column consisting of six plates was used to verify the removal efficiency of low-partial-pressure H 2 S (P H 2 S = 500 Pa) and the results showed that in the case of w MDEA = 0.5, w MEA = 0.075, and T = 313.2 K, the removal efficiency achieved 95% when the ratio of gas to liquid was 40, indicating that MEA-activated MDEA aqueous solutions are promising in the removal process of low-partial-pressure H 2 S.

Study of Various Aqueous and Non-Aqueous Amine Blends for Hydrogen Sulfide Removal from Natural Gas

“…For 3DEA-1P and DEAE-EO a higher reduction in the absorption capacity is seen. Overall, the results indicate that increase in amine concentration changes the vapor-liquid equilibria behavior of the system [16,27,41,42].…”

“…For 3DEA-1P and DEAE-EO a higher reduction in the absorption capacity is seen. Overall, the results indicate that increase in amine concentration changes the vapor-liquid equilibria behavior of the system [16,27,41,42]. The data at 50 wt% allows us to compare the absorption capacity of 3DEA-1P, DEAE-EO and DBEA in aqueous and MEG solutions with similar mole fraction (mole amine/mole solution).…”

“…The solubility of H 2 S in aqueous solutions of MDEA from 11.9 wt.% to 51 wt.% in the temperature range from 10 • C to 120 • C and H 2 S partial pressure from 0.141 kPa-6900 kPa were studied by various authors [16][17][18][19][20][21][22][23][24][25][26][27]. All the previous studies of aqueous MDEA showed similar trends like increasing the partial pressure of H 2 S (pH 2 S) increases H 2 S loading at given concentration and temperature, while the increase in amine concentration at a given temperature and pH 2 S decreases H 2 S loading.…”

Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

“…Many studies have shown that a mixed alkanolamine solution has better desulfurization performance than a single alkanolamine solution [ 9 , 10 , 11 ]. Our previous study indicated that adding small quantities of MEA to MDEA aqueous solutions can obviously improve the H 2 S absorption capacity and absorption rate [ 12 ].…”

“…In our previous studies, we used MDEA aqueous solutions promoted by two ILs, namely tetramethylammonium glycinate ([N 1111 ][Gly]) and tetramethylammonium arginate ([N 1111 ][Arg]), to explore the performances of such mixed solutions for absorbing H 2 S. The results showed that the two AAILs were superior to MEA in promoting the absorption of H 2 S by MDEA solution. Moreover, of these two promoters, the MDEA aqueous solutions promoted by [N 1111 ][Arg] exhibited the highest absorption capacity and absorption rate for low-concentration H 2 S. Therefore, [N 1111 ][Arg]-promoted MDEA aqueous solutions show commercial potential [ 12 , 25 ].…”