Development and Testing of Amine-Type Scavengers for Elimination of H2S from Liquid Sour Crudes

Sour crudes (i.e. > 0.5% sulfur) are of low quality and cause harm to equipment, the environment, and to humans. Chemical agents, known as scavengers, are used to scrub H₂S from crude oils, which may even be necessary to conform to legal transport laws prior to the crude entering a pipeline or railcar. Scavengers are either of the regenerative or non-regenerative type, and are used depending upon whether the pH or water content of the crude stream. The non-regenerative scavengers are usually triazines containing various sidechain constituents that make the scavenger more soluble depending on the type of crude (i.e. API, pH, water content, etc.). However, the conversion of triazines with H₂S lead to byproducts which foul downstream refinery equipment, particularly heat exchangers on overhead distillation streams.

In this project, typically used scavengers have been surveyed from the open literature to reveal those absorbents that allow the most effective scavenging of H₂S at wellhead applications, depending on crude oil quality. In addition, the use of ionic liquids as replacements for regenerative amines (i.e. monoethanolamine (MEA)) was also studied. Ionic liquids offer improved absorbent qualities while being easier and more economical to recover than MEA. The chemical processing, including recovery of scavenger or end use of products, will be presented for decision-making from the wellhead to the refinery. This work serves at the confluence of chemistry and chemical engineering for hydrogen sulfide removal and 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.