Temperature- and pH-Dependent Kinetics of the Aqueous Phase Hydrogen Sulfide Scavenging Reactions with MEA-Triazine

Abstract

A novel kinetic model for the aqueous phase hydrogen sulfide scavenging reactions using MEA-triazine (HET) is proposed. The assumptions of the model are based on experimental observations obtained by NMR spectroscopy, supporting the existence of 3,5-bis(2-hydroxyethyl)hexahydro-1,3,5-thiadiazine (TDZ) as a quantitative reaction intermediate and showing the protonation behavior of HET and the lack of protonation of 5-(2-hydroxyethyl)hexahydro-1,3,5-dithiazine (DTZ). Experimental kinetic data were obtained with a new in situ Raman spectroscopy setup, which enabled monitoring the time-variation of bisulfide concentrations in a batch stirred reacting system at temperatures of up to 75 °C for HET/HS − initial concentration ratios from 0.5 to 5. The optimal model parameters were regressed from the experimental data using a brute force optimization method. The rate constants of the first and second scavenging reactions were estimated to be 0.435 and 0.004 L mol −1 s −1 at 25 °C, and the activation energies were 68 and 57 kJ mol −1 , respectively.

Multifunctional biomass-based chemicals: H2S scavenging

“…28–30 Bisulfide has a characteristic peak at 2574 cm −1 in Raman spectra, which overlaps with neither MEA-triazine peaks nor the peaks of reaction products, thus allowing us to monitor the progress of the H 2 S scavenging reactions. 13,28,29…”

“…, not purified to the same extent, was found to match the performance, which is relevant for the intended technical use. While the use of MEA-triazine caused the pH to increase substantially, which in turn led the reaction to stall until lowering the pH by adding HCl, 13 the use of 12 did not change the pH to the same extent. In contrast, the new inositol-based scavenger continued scavenging and could remove all traces of HS − in the setup in approx.…”

“…Hence, MEA-dithiazine is not protonated under the applied reaction conditions and therefore does not react. 13…”

Introducing the I&ECR Virtual Collection of Industrial and Industrially Relevant Research (2022–2023)

“…Due to the importance of catalysis within industry, the Kinetics, Catalysis and Reaction Engineering topic area has historically been one of the largest areas within I&ECR . In the present collection, industrial researchers performed studies ranging from the post-synthesis modification of polyethylene terephthalate (PET), to hydrogenation of CO 2 to light olefins (recognized with a May 2023 cover), studies on the kinetics of H 2 S adsorption in monoethanolamine (MEA), the regeneration of Pd/Al 2 O 3 electrochemical catalysts, production of diacrylate monomers by transesterification (recognized with a December 2022 cover), the evolution of coke within beta zeolite catalysts during catalytic cracking, the relationship of fluoropolymer product quality and production efficiency, novel catalysts for polyisobutenyl succinic anhydride synthesis, a new activation procedure for Ziegler–Natta catalysts, a kinetics study related to safety regarding the decomposition of H 2 O 2 , and a study from Dow highlighting the conversion of syngas to olefins, featuring two researchers from the 2022 Class of Influential Researchers …”