Mechanistic Insights into the Efficiency of Formaldehyde-Based Compounds and Glyoxal as H2S Scavengers

Abstract

Hydrogen sulfide, H2S, poses significant challenges to the oil and gas industry due to environmental risks, safety concerns, and equipment corrosion. Nonregenerative scavengers like aldehyde-based compounds offer cost-effective solutions for the removal of H2S, crucial for reaching near-zero concentrations. However, the literature lacks comprehensive understanding of the physical-chemical aspects of H2S removal by aldehydes. Herein, we explored the reaction mechanisms involved in the H2S scavenging using aldehydes by density functional theory calculations. Thermodynamic and kinetic parameters were assessed, emphasizing the explicit role of water in lowering reaction barriers. We computed the thermochemical behavior for the formation of oligomeric compounds associated with fouling using aldehydes. Glyoxal-promoted processes presented lower energy barriers (12.5-17.5 kcal mol-1) compared to formaldehyde. Simulations also considered the hazardous nature of aldehydes by computing their formation from formaldehyde releaser compounds. These findings enhance the understanding of H2S scavenging and feature the potential of aldehyde as effective scavengers in the industry.