(664e) Relationship of Solubility and Thermodynamic Parameters for Amine-Containing Non-Regenerative H2S Scavengers
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Thermodynamics Needs of the Chemical Industry
Thursday, November 14, 2019 - 9:35am to 10:00am
Removal of H2S from oil and gas streams has been a priority, oftentimes a necessity, for upstream crude oil/gas facilities for decades. However, the advances in production, namely horizontal drilling and hydraulic fracking, have produced oils and natural gases that contain higher concentrations of H2S than previously seen. Crudes containing > 0.5 % sulfur are considered sour and must undergo separation and/or conversion processes to lower the H2S content prior to entering the midstream pipelines and railcars. H2S scavengers can be categorized into two types: regenerative and non-regenerative. Regenerative scavengers, such as alkanolamines, absorb H2S using reversible absorption with stripping recovery processes. With non-regenerative scavengers, an irreversible reaction converts the H2S to form sulfur-containing hydrocarbons. Non-regenerative scavengers are usually aldehydes, ethers, and amines (i.e. acrolein, glyoxal, formaldehyde, alpha-aminoethers, or triazines). Triazine-based scavengers have become the most widely used of the reactive-type scavengers. 1,3,5-hexahydrotriazine is the most frequently used; however, its byproducts equipment fouling, particularly overhead condensers within refineries.
These harmful effects have led to molecular adaptations to the basic triazine molecule whose byproducts would be benign to equipment fouling and corrosion. Varying side chains have the impact of making the triazine scavenger more (or less) soluble in aqueous (or non-polar) crudes. In addition, these side chains could be tailored to be more active for sour gas, rather than sour liquid crude streams. Side chain modifications lead to uncertainty of solubility, liquid/gas interactions, and possible byproduct complications. In this work, solubility and scavenger/ion interactions have been determined for triazines containing ethanolic, amino, bromine, and acrolein substituents, namely 1,3,5-Triacryloylhexahydro-1,3,5-triazine, cyanuric acid, and 1,3,5-Tris(2-hydroxyethyl)cyanuric acid. By adding salts to the mixture, the solubility data yields insightful information towards the ionic mediums in which these materials could be used. Moreover, Setchenowâs coefficient, the octanol/water partition coefficients, and the activity coefficients have been determined to examine the potential fate these scavengers when considering environmental factors. The experimental results and model development will be presented.