(399b) An Investigation on Chemical Absorbents for the Effective Removal of Hydrogen Sulfide from Crude Oils

Tracy J. Benson, Obakore Agbroko, and Karishma Piler

Sour crudes (containing > 0.5% sulfur) are of low quality and cause harm to equipment, the environment, and to humans. Sustainable measures for crude oil sweetening are of significant importance. Removing of H₂S at the wellhead before transporting via pipeline or railway increases the value of crude oil and may even be necessary to conform to legal transport laws. Chemical agents, known as scavengers, are used to scrub H₂S from crude oils. Scavengers are either of the regenerative or non-regenerative type. The type of scavenger used depends upon the size of the wellhead facility as well as the pH or water content of the crude stream. The aim of this work is directed towards smaller wellhead facilities where onsite scrubbing and stripping operations are not feasible, making non-regenerative scavengers a better option.

From a survey of the literature, non-regenerative scavengers, chiefly of the triazine type, vary by constituent side chain moieties that allow the scavenger to be more soluble in one medium versus another. Yet, little information is provided about the true solubility of these scavengers in various crude mediums. Therefore, a series of triazine-type scavengers with differing side chains have been tested in a series of solvents ranging from hydrophilic to hydrophobic with the purpose of understanding the solubility phenomenon as well as the appropriate liquid activity coefficient models for these systems. The chemical processing, including recovery of scavenger or end use of products, will be discussed for decision-making at the confluence of chemistry and chemical engineering for hydrogen sulfide removal. This work seeks how and why some scavengers perform better for some crudes and environmental conditions than others with the intent to develop designer scavengers and processing conditions for the crude oil industry.