Molecular dynamics simulation of natural gas sweetening by monoethanolamine

The aim of the study is to investigate sweeting process of sour gas by dynamic simulation of monoethanolamine (MEA) molecule. In the present paper using molecular dynamic simulation, the interaction of sour gas mixture included methane, ethane and H2S with MEA as absorption was also investigated the quantum method DFT B3LYP 6-311 (+) G** was used for electric charge calculation. The simulation results confirmed that the tendency of the H2S molecule is to be absorbed to amine nitrogen and oxygen hydroxyl group in MEA. No tendency for strong interaction between sulfur atoms of H2S molecule and hydrogen of amine or hydroxyl groups was observed. The investigation of changing distance between the hydrogen of H2S and nitrogen/oxygen of MEA confirmed a stable between hydrogen atoms of H2S and nitrogen/oxygen atoms in MEA. Also the investigation of distance changing show movement of hydrogen atoms of H2S molecule which interacted with MEA molecule in the time frame of the simulation. This study was observed that after absorption of H2S molecule by MEA molecules sour of them made the bridge for connection of MEA molecules with each other. Actually H2S molecules after interact with MEA molecules used addition their free hydrogen forinteraction and Making Bridge. Finally a structure of some MEA molecules are joined together, which are stable up to end of the simulation.