Structural Elucidation of the Solid Byproduct from the Use of 1,3,5-Tris(hydroxyalkyl)hexahydro-<i>s</i>-triazine Based Hydrogen Sulfide Scavengers

Taylor, Graeme K.; Matherly, Ron

doi:10.1021/ie101985v

Cited by 37 publications

(46 citation statements)

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“…TDZ, in turn, can also undergo protonation and reaction with HS – , leading to 5-(2-hydroxyethyl)hexahydro-1,3,5-dithiazine (dithiazine, DTZ) and another molecule of MEA. The substitution of a third sulfur atom into the triazine ring, which would give trithiane, is instead typically not observed. ,− This is presumably attributed to the absence of a nucleophilic carbon center in DTZ susceptible to an attack by HS – , as opposed to TDZ . Thus, from a stoichiometric standpoint, 2 mol of sulfur from H 2 S can be converted into DTZ using 1 mol of HET, with the liberation of 2 mol of MEA.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Aqueous Phase Reaction of Hydrogen Sulfide with MEA-Triazine Using In Situ Raman Spectroscopy

Romero

Kucheryavskiy

Maschietti

2021

Ind. Eng. Chem. Res.

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A method for quantitation of bisulfide in the aqueous phase reactions of H 2 S scavenging with MEA-triazine is proposed. The method is based on time-resolved in situ Raman spectroscopy, thus allowing in situ monitoring of the reactions. The method is applied to obtain the kinetic data of the reactions in batch configuration at room temperature for initial pH values of 9, 10, and 11 and MEA-triazine/bisulfide initial concentration ratios in the range of 0.5−10. The pH increases remarkably during the reactions, causing a substantial decrease in the rate of disappearance of bisulfide. If the system is reacidified, complete depletion of bisulfide can be achieved, evidencing the irreversibility of the scavenging reactions. The results are also supported by a qualitative analysis of the trends of the characteristic Raman peaks of MEA-triazine, dithiazine, and monoethanolamine. These trends are in line with the currently accepted reaction scheme, consisting of two scavenging reactions in series.

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Section: Introductionmentioning

confidence: 99%

Experimental Study of the Aqueous Phase Reaction of Hydrogen Sulfide with MEA-Triazine Using In Situ Raman Spectroscopy

Romero

Kucheryavskiy

Maschietti

2021

Ind. Eng. Chem. Res.

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“…the scavenger, or an amorphous dithiazine polymer for which strong evidence has been produced. [6][7][8] The formation of the precipitate must originate from compounds initially present or formed in the scavenging mixture, but none of the previously detected compounds seems to be able to explain how the precipitate is formed. As a result, it was desired to investigate the composition of the mixture at different stages of scavenging and, to do this, electrospray ionisation mass spectrometry (ESI-MS) was employed.…”

Section: Introductionmentioning

confidence: 99%

Use of ESI-MS to Determine Reaction Pathway for Hydrogen Sulphide Scavenging with 1,3,5-Tri-(2-Hydroxyethyl)-Hexahydro-s-Triazine

Madsen

Søgaard

2012

Eur J Mass Spectrom (Chichester)

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To study the reaction between hydrogen sulphide and 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine, which is an often used hydrogen sulphide scavenger, electrospray ionisation mass spectrometry (ESI-MS) was used. The investigation was carried out in positive mode and tandem mass spectrometry was used to investigate the nature of unknown peaks in the mass spectra. The reaction was found to proceed as expected from theory with the triazine reacting with hydrogen sulphide to form the corresponding thiadiazine. This species subsequently reacted with a second hydrogen sulphide molecule to form the dithiazine species, thereby confirming previously obtained results and showing the ability of the ESI-MS method for studying the scavenging reaction. The final theoretical product s-trithiane was not detected. Furthermore, fragmentation products of thiadiazine and dithiazine were detected in the solution and possible pathways and structures were suggested to describe the observed fragments. In these, thiadiazine fragmented to 2-(methylidene amino)-ethanol and 2-(1,3-thiazetidin-3-yl)-ethanol and N-(2-hydroxyethyl)-N-(sulfanylmethyl)-ethaniminium, which underwent a further fragmentation to N-methyl-N-(2-oxoethyl)-methaniminium. Dithiazine fragmented to N-methyl-N-(2-oxoethyl)-methaniminium as well. The byproduct from this reaction is methanedithiol, which was not detected due to its low polarity. IntroductionDuring production of oil and gas, a commonly encountered pollutant is hydrogen sulphide gas. Hydrogen sulphide is both highly toxic and corrosive and must therefore be removed. 1,2In general, two strategies exist for this: regenerative and non-regenerative. For fields with H 2 S concentrations below a few hundred ppm, the most economical solution is the non-regenerative one and the triazine-based molecules are among the most frequently used scavengers.3 Triazines have the advantage that they can be modified to become more or less hydrophilic by using different functional groups on the nitrogen atoms. Often, a polar functional group is used but also purely nonpolar alkyl side groups have been investigated. 4 The reasons why triazines are so widely used are that they are H 2 S-selective because of their tertiary nitrogen atoms, the reactions products are corrosion inhibitors and the spent material has a low toxicity, making waste management easier. 3When applied after extraction from the well during the separation process on the platform, a water soluble triazine is chosen to ensure that the reaction products are disposed of with the produced water. One of the most commonly chosen water soluble triazines is 1,3,5-tri-(2-hydroxyethyl)-hexahydro-striazine (triazine).The accepted theoretical reaction pathway for the reaction between triazine and H 2 S is shown in Figure 1. Triazine reacts with H 2 S in an S N 2 reaction, where a nitrogen atom is substituted with a sulphur atom forming 3,5-di-(2-hydroxyethyl)-hexahydro-1,3,5-thiadiazine (thiadiazine). Thiadiazine may then further react with H 2 S forming 5-(2-hydroxyethyl)-he...

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“…Furthermore, while hydrogen sulfide can theoretically react with a third molecule to yield a trithiane molecule, this reaction does not proceed under most conditions. As a result, sparingly soluble solid dithiazine (3) molecules or an amorphous polymerized dithiazine material are the typical final products under aqueous reaction conditions (Taylor & Matherly, 2011;Taylor et al, 2013;Wang et al, 2020). ISSN 2056-9890 Engineering protocols are implemented into the pipeline flow systems so that the sparingly soluble solids from the spent scavenger are continuously removed.…”

Section: Chemical Contextmentioning

confidence: 99%

An orthorhombic polymorph of 2-(1,3,5-dithiazinan-5-yl)ethanol or MEA-dithiazine

Schultheiss

Holtsclaw

Zeller

2022

Acta Crystallogr E Cryst Commun

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Substituted triazines are a class of compounds utilized for scavenging and sequestering hydrogen sulfide in oil and gas production operations. The reaction of one of these triazines under field conditions resulted in the formation of the title compound, 2-(1,3,5-dithiazinan-5-yl)ethanol, C5H11NOS2, or MEA-dithiazine. Polymorphic form I, in space group I41/a, was first reported in 2004 and its extended structure displays one-dimensional, helical strands connected through O—H...O hydrogen bonds. We describe here the form II polymorph of the title compound, which crystallizes in the orthorhombic space group Pbca as centrosymmetric dimers through pairwise O—H...N hydrogen bonds from the hydroxyl moiety to the nitrogen atom of an adjacent molecule.

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Structural Elucidation of the Solid Byproduct from the Use of 1,3,5-Tris(hydroxyalkyl)hexahydro-s-triazine Based Hydrogen Sulfide Scavengers

Cited by 37 publications

References 4 publications

Experimental Study of the Aqueous Phase Reaction of Hydrogen Sulfide with MEA-Triazine Using In Situ Raman Spectroscopy

Experimental Study of the Aqueous Phase Reaction of Hydrogen Sulfide with MEA-Triazine Using In Situ Raman Spectroscopy

Use of ESI-MS to Determine Reaction Pathway for Hydrogen Sulphide Scavenging with 1,3,5-Tri-(2-Hydroxyethyl)-Hexahydro-s-Triazine

An orthorhombic polymorph of 2-(1,3,5-dithiazinan-5-yl)ethanol or MEA-dithiazine

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