High pressure measurement and thermodynamic modeling the solubility of H2S in the aqueous N-methyldiethanolamine + 2-amino-2-methyl-1-propanol + piperazine systems

Highlight
• A statistic high pressure cell is used for measurement of H2S solubility in alkanolamine blends.
• The MDEA-piperazine-AMP systems are investigated.
• Piperazine improves H2S solubility in the activated MDEA-AMP system at high loading.
• Electrolyte NRTL is used for modeling of H2S solubility in activated MDEA-AMP systems.

Removal of hydrogen sulfide and carbon dioxide from sour gas is important in the natural gas treatment process and capturing of acid gases from flue gases. Moreover, for the design and construction of gas contactor equipment, experimental data of the solubility of H2S and CO2 in aqueous alkanolamines are needed. In this work using a volumetric static method, solubility of H2S in aqueous blends of N-methyldiethanolamine (MDEA), 2-amino-2methyl-1-propanol (AMP) and piperazine (Pz) with different compositions are obtained at 313.15, 328.15 and 343.15 K over the pressure range of 1–21 bar. The composition of the MDEA is fixed at 25 mass % and the composition of the AMP and Pz are changed as (20, 15, 10, 5) mass % and (0, 5, 10, 15) mass %, respectively, so that the sum of mass fractions of all amines (MDEA + AMP + PZ) is kept constant. The experimental data are presented as the partial pressure of H2S against acid gas loading (moles H2S/total moles of amine). Considering the present results at the given conditions, it is observed that in the gas loading region less than one, blending Pz with an aqueous solution of the MDEA + AMP leads to reduction of absorption of the H2S.