Solubility of Hexane/Heptane in Methyldiethanolamine (MDEA) aqueous solution

Abstract

Aqueous solutions of alkanolamines are commonly used in natural gas industry to absorb acid gases (CO2 and H2S) from natural gas and hydrocarbon liquids. The dissolved hydrocarbons in the alkanolamines are considered as lost product and must be minimized. Even though light hydrocarbons have higher solubility in the alkanolamines than heavy hydrocarbons; the heavy hydrocarbons contribute to the foaming problem which could significantly increases the hydrocarbons losses and decrease the absorption process efficiency. Thus, the solubility information for heavy hydrocarbon is of high importance not just to determine the magnitude of hydrocarbons losses but also for their influence on alkanolamines foaming. This thesis presents new experimental solubility data of hexane and heptane in aqueous amine solutions. Simple equilibrium cells were used to measure the solubility of hydrocarbons in aqueous amine systems in the range: 298–328 K. Analyses of aqueous liquid samples were performed using a gas chromatograph. It has been observed that hexane and heptane solubility in MDEA solutions increased with increasing temperature. Also, increasing amine concentration in the test solution increased the solubility of hexane and heptane. Simple models were developed in order to represent the activity coefficient of hexane and heptane in the aqueous MDEA solution in the range of 40 – 50 wt % MDEA. The Henry's law- based model allowed for a more direct comparison between the solubilities in pure water and in the aqueous solution of MDEA.

Date of Award	2015
Original language	American English
Supervisor	Fawzi Banat (Supervisor)