Formation Of Organic Sulfur Compounds Research Articles

The initiation stage of thermochemical sulfate reduction: An isotopic and computational study

Thermochemical sulfate reduction (TSR) is one of the most important organic-inorganic reactions in petroleum reservoirs which significantly affects production and processing risks. The initiation (non-catalyzed) stage of TSR is critical in constructing a reliable kinetic model to predict this reaction. There is a large gap in our understanding of the mechanisms involved in this stage. In the present study, we used hydrous pyrolysis experiments with Na2SO4 and 1-dodecene as model compounds at pH= 1, and temperatures of 250 °C and 300 °C to simulate this early TSR stage. We measured and calculated the sulfur isotopic fractionations of sulfate, H2S and individual organic sulfur compounds (OSC). A thermodynamic model was used to determine the concentrations of the different sulfate species (H2SO4, HSO4¯, SO42-) at the experimental conditions. We then used ab initio calculations to determine possible radical and non-radical reaction mechanisms to explain the experimental results. During all the experiments, sulfate was consumed gradually while H2S and OSC were produced. The residual sulfate was 34S enriched up to 10.7‰ relative to the initial sulfate as pyrolysis time advanced. The produced H2S and OSC were typically about 21‰ 34S depleted relative to co-existing sulfate. The formation of OSC, such as C24 sulfides and C12 thiophenes, during the experiments and their similar δ34S values, suggest a common precursor and that radical mechanisms are involved in their formation. Calculated activation energies and free energies (Ea and ∆G‡, respectively) for the radical TSR mechanisms (20.6–34.1 and 32.3–44.4 kcal mol−1, respectively) yielded lower values than the non-radical TSR mechanisms (53.5–68.5 and 59.7–78.1 kcal mol−1, respectively). However, the calculated kinetic fractionation factors for the non-radical mechanism correlated better with the 11–12‰ experimental fractionation factor of current and previous studies. This similarity between the experimental and computational results indicates that these non-radical rather than radical mechanisms were likely involved in the reduction of sulfate in our experiments. Despite the lower activation energies, the radical TSR mechanisms are not dominant in our experimental system, probably due to competing reactions of the active radical species (alkyl and allyl radicals). Nevertheless, under natural conditions, the significantly lower amount of alkenes is expected to reduce the competition on the active alkyl and allyl radicals for alkylation, making these radical mechanisms competing pathways for the initiation stage of TSR.

Two modes of gypsum replacement by carbonate and native sulfur in the Lorca Basin, SE Spain

Organoclastic sulfate reduction and bacterial sulfide oxidation have been suggested to explain the formation of authigenic carbonate and native sulfur replacing gypsum in the Lorca Basin, Spain. To gain more insight into the nature of this replacement, two types of sulfur-bearing carbonate (laminated and brecciated) from the late Miocene Lorca Basin were studied. Petrographic observations revealed that a sulfur-bearing laminated carbonate consists of clay-rich and dolomite-rich laminae with carbonate and native sulfur pseudomorphs after gypsum. Positive δ18Ocarbonate values in the laminae (δ18O = 2.6‰) and lipid biomarkers of halophilic archaea (e.g., extended archaeol) suggest formation under hypersaline conditions. Bacterial sulfate reduction, evidenced by biomarkers such as iso-C15, iso-C16, and iso-C17 fatty acids, produced hydrogen sulfide inducing the abiotic formation of organic sulfur compounds. Gypsum in the laminated carbonate likely dissolved due to undersaturation as evidenced by a low content of carbonate-associated sulfate (3,668 ppm) and 34S-enriched native sulfur (δ34S = 22.4‰), reflecting sulfate limitation. Such 34S-enrichment implies limited fluid flow, which probably restricted the supply of molecular oxygen required for native sulfur formation through oxidation of hydrogen sulfide. Alternatively, sulfate-reducing bacteria may have mediated native sulfur formation directly as a stress response to environmental conditions. The formation of sulfur-bearing calcite in brecciated carbonates is due to post-depositional alteration. Negative δ18O values of the calcite (δ18O = −1.5‰) and a tenfold decrease in carbonate-associated sulfate content (752 ppm) suggest gypsum dissolution and subsequent calcite precipitation from meteoric water. Relatively 34S-depleted native sulfur (δ34S = 13.1‰) leaves it ambiguous whether meteoric water influx could have supplied sufficient molecular oxygen for oxidation of hydrogen sulfide. In case of the brecciated carbonate, methanogenesis, anaerobic oxidation of methane, and bacterial sulfate reduction apparently mediated the formation of secondary minerals as indicated by 13C-depleted lipid biomarkers representative for the respective metabolisms. This study reveals that the conditions and timing of gypsum replacement are variable–taking place 1) during or shortly after gypsum deposition or 2) significantly after sedimentation–and suggests that methanogens in addition to anaerobic methanotrophic archaea and sulfate-reducing bacteria may be involved in the mineral-forming processes in the sedimentary subsurface.

Formation of organic sulfur compounds through SO<sub>2</sub>-initiated photochemistry of PAHs and dimethylsulfoxide at the air-water interface

Abstract. The presence of organic sulfur compounds (OS) at the water surface acting as organic surfactants, may influence the air-water interaction and contribute to new particle formation in the atmosphere. However, the impact of ubiquitous anthropogenic pollutant emissions, such as SO2 and polycyclic aromatic hydrocarbons (PAHs) on the formation of OS at the air-water interface still remains unknown. Here, we observe large amounts of OS formation in the presence of SO2, upon irradiation of aqueous solutions containing typical PAHs, such as pyrene (PYR), fluoranthene (FLA), and phenanthrene (PHE) as well as dimethylsulfoxide (DMSO). We observe rapid formation of several gaseous OSs from light-induced heterogeneous reactions of SO2 with either DMSO or a mixture of PAHs and DMSO (PAHs/DMSO), and some of these OSs (e.g. methanesulfonic acid) are well established secondary organic aerosol (SOA) precursors. A myriad of OSs and unsaturated compounds are produced and detected in the aqueous phase. The tentative reaction pathways are supported by theoretical calculations of the Gibbs energy of reactions. Our findings provide new insights into potential sources and formation pathways of OSs occurring at the water (sea, lake, river) surface, that should be considered in future model studies for a better representation of the air-water interaction and SOA formation processes.

Abiotic formation of dissolved organic sulfur in anoxic sediments of Santa Barbara Basin

Sulfurization has been found to enhance organic matter preservation and petroleum formation in marine sediments. However, we do not yet have a comprehensive understanding of sulfurization mechanisms. In this study, we investigated several possible mechanisms of dissolved organic sulfur (DOS) formation in the top 4.5 m of anoxic sediments of Santa Barbara Basin (SBB), California Borderland. Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS), we identified chemical formulas of potential dissolved organic matter (DOM) precursors to these DOS compounds. We also examined how the formulas of abiotically formed DOS changed as a function of depth across a major redox gradient.Results show that abiotic nucleophilic addition reactions involving bisulfide (HS−) and polysulfide (HSx−) are the major sulfurization pathways that form DOS in anoxic pore waters of SBB sediments. We identified 2124 unique DOS formulas that could be generated from the addition of HS− and HSx− to 2203 DOM formulas, and this accounted for ∼70% of all DOS formulas detected in these pore waters. Examining the DOM formulas that served as reactants in the abiotic sulfurization reactions, we found that 64% contained only carbon, hydrogen, and oxygen (CHO formulas) while the remainder (34%) included nitrogen (DON formulas). Our results revealed high reactivity toward sulfurization among many of the CHO and DON formulas that have H/C and O/C elemental ratios that overlap with those of carboxyl-rich alicyclic molecules (CRAM). This specific class of formulas could play an important role in the formation of organic sulfur compounds in sulfidic marine ecosystems, and in the formation of sulfur-containing protokerogen in marine sediments. Our results further suggest that anoxic sediments are a source of DOS compounds to the oceans.

Analysis of aromatic hydrocarbon in medium- to high-sulfur coals from Fenxi, Shanxi Province

Purpose This study aims to investigate the compositional characteristics of aromatic hydrocarbons extracted from coals and to describe how the sulfur content influences the properties of coals and whether widely accepted maturity parameters are suitable for medium- to high-sulfur coal. Design/methodology/approach Four samples of medium- to high-sulfur coal were obtained from Fenxi, Shanxi Province, and studied using gas chromatography and gas chromatography–mass spectrometry (GC-MS). Findings The GC-MS results showed that there were five series of compounds were identified in the aromatic fractions: naphthalenes, phenanthrenes, oxygen-containing compounds, biphenyls and sulfur-containing compounds. The substituent group was mainly methyl. The content of dibenzothiophenes was high, which was attributed to their high thermodynamic stability. The presence of sulfur reduced the content of oxygen-containing compounds. A depositional environment that facilitated the formation of organic sulfur compounds led to a higher content of naphthalenes. Originality/value The development of methods for removing organic sulfur compounds would benefit from a study of their nature, which would be important for improving the use of coal.

Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰).Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4 dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and provide important mechanistic details about the overall TSR process.

A simulation on the formation of organic sulfur compounds in petroleum from thermochemical sulfate reduction

Thermochemical reduction of magnesium sulphate with n-pentane was carried out in an autoclave in the presence of water at high temperature and pressure to simulate the origination of organic sulfur compounds in petroleum from thermochemical sulphate reduction (TSR). The products of 3 phases (gas, oil, and solid) were analyzed by some advanced analytical methods including gas chromatography, microcoulometry, FT-IR, and X-ray diffraction. Results show that the TSR reaction occurred at 425–525°C with MgO, C, H 2S, CO 2, and a series of organic sulfur compounds such as mercaptans, sulfoethers, and thiophenes as the main products. The reaction kinetics was studied and the calculated activation energy is 58.0 kJ/mol.

Niobium rich SBA-15 materials – preparation, characterisation and catalytic activity

Hexagonally ordered mesoporous niobiosilicates of SBA-15 type were synthesised by a new synthesis route in which the use of hydrochloric acid was avoided. This route allowed the incorporation of much higher amounts of niobium into the mesoporous network (Si/Nb between 15 and 5) as compared to the conventional method of preparation. The location of niobium was determined by UV–Vis and XRD techniques. The latter combined with N 2 adsorption measurements allowed the estimation of texture/structure parameters. The high niobium content in the NbSBA-15 had a significant impact on the sulphurisation of methanol leading to the formation of organic sulphur compounds. It is well correlated with the acidity of the materials measured by pyridine adsorption followed by FTIR studies. Such a relationship was not observed for oxidation of methanol and epoxidation of cyclohexene showing that the redox properties are not linear related to the amount of niobium if Si/Nb is equal or below 15 (as applied in this work).

An experimental study of the low-temperature sulfurization of carbohydrates

Sulfurization of carbohydrates has been suggested as an important mechanism for the preservation of organic matter. To study this process, different monosaccharides were sulfurized under laboratory conditions at relatively low temperature (50 °C). The products formed after cleavage of polysulfide linkages were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry after appropriate derivatization. Selected products were isolated by preparative GC and their structures were identified by nuclear magnetic resonance spectroscopy. During these experiments all monosaccharides were completely converted into organic sulfur compounds (OSCs) and monosaccharides with the carbonyl function replaced by sulfur formed a substantial part of the GC-amenable OSCs. The structures of other OSCs formed indicated that cleavage of C–C bonds and racemization also took place during these experiments. The yield of recoverable OSCs after cleavage of polysulfide linkages was relatively low (<5% of the starting monosaccharide), indicating that most of the sulfurization products were still non GC-amenable and thus, for example, linked through monosulfide linkages. Flash pyrolysates of the sulfurized carbohydrate material contained in all cases relatively high amounts of short-chain alkylated (C0–C5) thiophenes, comparable to those obtained from S-rich kerogen. The structure of the monosaccharide used in the experiments had no effect on the alkylthiophene distribution. These results provide experimental evidence that sulfurization of monosaccharides at relatively low temperatures can result in the formation of OSCs, most likely starting with sulfurization of the carbonyl functionality. Preservation of carbohydrates through sulfurization may thus be an important pathway of preservation of organic matter in anoxic depositional environments.

Quantification and Reduction of Organic Sulfur Compound Formation in a Commercial Wood Pulping Process

This study experimentally quantified the formation of organic sulfur compounds in a commercial SuperBatch kraft pulping process using a laboratory pilot-scale digester. The results indicate that wood chips not only can adsorb HS- but also methyl mercaptan (MM) in the black liquor used for pretreatment during the two pretreatment stages. The absorption rate of MM is much faster than that of HS-. In the third stage of SuperBatch pulping, the rate of formation of MM and dimethyl sulfide (DMS) is very similar to that found in conventional batch kraft pulping processes. The study examined the applicability of the phase transition cooking (PTC) concept for reducing organic sulfur compounds in pulping, previously developed in laboratory batch pulping using a bomb-type digester, in a SuperBatch process. It was confirmed that there is a phase transition point (PTP) corresponding to PTC in SuperBatch pulping beyond which further delignification significantly increases the formation of volatile organic sulfur compounds. The results indicate that a 40% reduction of TRS formation can be achieved by using PTC.

In-digester reduction of organic sulfur compounds in kraft pulping

This experimental research examines the relationship between the formation of organic sulfur compounds and delignification during kraft wood pulping. A phase transition point (PTP) was discovered below and above which the formation of total organic sulfur compounds, with respect to delignification, changes significantly. The PTP occurs at approximately pulp kappa number 35 for softwoods and 20 for hardwoods. The PTP is directly related to the phase transition in kraft delignification from bulk to residual delignification. Significant in-digester odor reduction can be achieved using phase transition cooking (PTC), i.e. limiting delignification to the bulk delignification phase or the PTP. It was also discovered that anthraquinone (AQ) as a catalytic additive can reduce organic sulfur compound formation during kraft pulping. The reduction of sulfur compound formation is linearly proportional to the square root of the level of AQ addition (in percent). A 40% in-digester reduction in total reduced sulfur (TRS) formation can be achieved by using PTC and AQ in kraft pulping.

Organic sulfur compounds formed during early diagenesis in Black Sea sediments

Sediments from Units I and II of the Black Sea were analyzed to assess the early diagenetic formation of organic sulfur compounds (OSC). A series of isomeric C 28-2,4-dialkylthiophenes was found at low concentrations in surface sediments. OSC with C 25-highly branched isoprenoid (RBI) skeletons were not found in surface sediments even though there was a rapid decrease in the concentrations of C 25-HBI alkenes in the same sediments, nor were OSC found which contained carbon skeletons derived from C 37–C 39 alkenes which are also abundant in the sediment. As depth increased in Unit I, concentrations of the C 28-2,4-dialkylthiophenes decreased while C 25- and C 30-HBI thiolanes appeared at the bottom of Unit I and increased in concentration into Unit II. Treatment of macromolecular material from sediment extracts with Raney nickel yielded phytane as the dominant hydrocarbon as well as series of C 25- and C 30-HBI hydrocarbons, β-carotane, and isorenieratane. These latter two components were generally absent from the free hydrocarbon fractions. These results indicate that sulfur incorporation into functionalized lipids can occur during the very early stages of sedimentary diagenesis, even at the sediment-water interface. On the other hand, the rapid loss of C 25-HBI alkenes in surface sediments could not be accounted for by sulfur quenching, and other potential OSC-precursors, such as C 37-C 39 alkenes, also apparently did not incorporate sulfur into readily-analyzable material.

Natural sulphurization of ketones and aldehydes: A key reaction in the formation of organic sulphur compounds

Acids, ketones, aldehydes, and alcohols were tested in the laboratory as substrates for hydrosulphurization under mild conditions. Ketone and aldehyde model compounds (i.e., 2-nonanone, nonanal, cholestan-3-one and phytenal) formed significant amounts of organic sulphur compounds, in which the oxo group was substituted by a polysulphide moiety. These results are used to explain the formation of several organic sulphur compounds reported in immature S-rich sediments.

Hydrodesulfurization of a High Organic Sulfur Spanish Lignite with Impregnated Nickel Sulfate

Abstract The removal of sulfur from Mequinenza (Spanish) lignite was investigated by hydrodesulfurization reactions. This lignite has an unusually high sulfur content, 9.9% (dry basis) of which about 90% is organic sulfur. The lignite was impregnated with nickel sulfate prior to reactions, at various levels of nickel loading. The reactions were performed in bench-scale microautoclave reactors in 6.9 MPa hydrogen at 250-325° C for 1 hour. The best result was the removal of 63% of the sulfur in the lignite, achieved with 1.5% nickel loading at 325° C. Compared to reactions without impregnated catalyst, the addition of nickel sulfate enhances the hydrodesulfurization at all reaction temperatures, and improves the selectivity to H2S. A high selectivity to H2S minimizes the formation of organic sulfur compounds in by-product liquids

Analysis, structure and geochemical significance of organically-bound sulphur in the geosphere: State of the art and future research

This paper reviews the developments of the 1980s in the characterisation of organically-bound sulphur in the geosphere and summarises the geochemical significance of the results obtained by these studies. The identification of more than 1500 novel OSC (organic sulphur compounds) with structures related to biochemical precursors in mostly immature sediments and crude oils has led to a better understanding of the process by which inorganic sulphur is incorporated into organic matter. The sulphur enrichment of organic matter probably takes place via “quenching” of functionalised lipids by sulphur at the early stages of sediment diagenesis or even in the water column. This results in the formation of OSC with specific structures which may be applied as palaeoenvironmental indicators. Hydrocarbon biological marker distributions may be heavily biased by diverting functionalised potential hydrocarbon precursors in OSC. Thermal evolution of sedimentary organic matter also affects the composition of OSC and when these changes are completely understood these compounds may be applied as maturity parameters as well. Recent developments in the characterisation of organically-bound sulphur present in macromolecular substances, i.e. kerogen, asphaltenes and high-molecular-weight fractions of crude oils and bitumens, show that the sulphur-containing moieties in these substances are formed in a similar way to the low-molecular-weight OSC. Sulphur incorporation into functionalised lipids in an intermolecular fashion should be considered as an important pathway for the formation of macromolecular substances. The abundance of organic sulphur in these substances also has a marked influence on their thermal evolution. Hiatuses in our present knowledge are numerous and stimulate future studies. Priorities are: the unravelling of the actual mechanisms of sulphur incorporation into organic matter and a better understanding of the diagenetic pathways of OSC and sulphur-containing macromolecular substances.

An analytical investigation of the thermal degradation of a cation-exchange resin — part 1

In this first part of a two-part investigation the preliminary results of the thermal degradation at 300 °C in an aqueous milieu of a cation-exchange resin are presented. The resin is a sulphonated copolymer of styrene (92%) and divinylbenzene. The desulphonation and degradation of the resin was followed by the analytical techniques of laser microprobe mass analysis (LAMMA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Sulphuric acid attack on the metallic surface of the pyrolysis crucible was verified and the identification of the resultant inorganic products was performed by LAMMA and Fourier transform infrared spectroscopy. Nuclear magnetic resonance spectroscopy indicated that few or no unsaturated organic degradation products were formed. GC/MS identified a predominant degradation product as 1,3-diphenylpropane. A Py-GC/MS study on resin residues with respect to varying pyrolysis temperatures and times shows that the formation of organic sulphur compounds are favoured at higher temperatures. This implies that some form of reduction occurs during thermal degradation.

CORRELATION OF HEAT OF FORMATION DATA FOR ORGANIC SULFUR COMPOUNDS1

The method of Allen was used to correlate unpublished and recently published Bureau of Mines results for the heats of formation of organic sulfur compounds. Six parameters were evaluated from data for 25 acyclic alkane thiols, sulfides and disulfides. With the inclusion of appropriate strain energies, the results for seven cyclic sulfur compounds also were correlated. For all 32 compounds, the average deviation between calculated and experimental values, 0.17 kcal. mole/sup -1/, was a little less than the average experimental uncertainty interval, 0.22 kcal. mole/sup -1/. The correlation can be used to predict reliable values of heat of formation for many other organic sulfur compounds.

Origin and Decomposition of Carbon Disulfide in Gas Making III—Some Chemical and Thermodynamic Effects in Formation of Organic Sulfur Compounds1,2

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrigin and Decomposition of Carbon Disulfide in Gas Making III—Some Chemical and Thermodynamic Effects in Formation of Organic Sulfur Compounds1,2Wilbert J. Huff and John C. HoltzCite this: Ind. Eng. Chem. 1930, 22, 6, 639–645Publication Date (Print):June 1, 1930Publication History Published online1 May 2002Published inissue 1 June 1930https://doi.org/10.1021/ie50246a025RIGHTS & PERMISSIONSArticle Views25Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (892 KB) Get e-Alerts