In gas sweetening plants, amines are used for separating the CO2 and H2S from natural gases. The performance of amines is based on the reaction of a week base with week acid and producing an amine salt which is soluble in water. Commercially alkanolamines for the approach are monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP). The use of amine mixtures employing MDEA, MEA, and DEA have been investigated for various cases using a process simulation program called TSWEET. In all cases, 50 wt% total amines in water were used with the base case as 50 wt% MDEA. MEA and DEA were used as additives to form the mixture. The results reveal that, at high pressures, amine mixtures have little or no advantage in the cases studied. As the pressure is lowered, it becomes more difficult for MDEA to meet residual gas requirements and mixtures can usually improve plant performance.

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