Sulfur Compounds In Crude Oil Research Articles

Pechini Sol-Gel Synthesis and Characterization of NiWO4/W5O14/WO3 Nanocomposite for Photocatalytic Desulfurization of Thiophene

One of the most important problems in the oil industry is the presence of sulfur and sulfur compounds in crude oil. Sulfur compounds in crude oil can have detrimental effects on the environment, equipment, catalysts, and end products. One of the most important goals of researchers in recent years is to sweeten petroleum products from these compounds. This study aims to use NiWO4/W5O14/WO3 composite nanostructure to solve this problem using the photocatalytic oxidative desulfurization method. This composite nanostructure has been synthesized by Pechini sol-gel method with high purity at low temperature and examined by XRD, EDS, FESEM, and FT-IR analysis. Due to the presence of WO3 in the composition, the bandgap was greatly reduced and the efficiency was increased. As a result, the nanostructure could degrade more than 73% of the sulfur in thiophene in 180 min under visible light. By optimizing the amount of photocatalyst and irradiation time, the efficiency can be improved.

Determination of water content of crude oil by azeotropic distillation Karl Fischer coulometric titration

The determination of water content in crude oil is important for oil transportation, refining, and trade. However, the sensitivity and accuracy of the conventional azeotropic distillation (AD) method are inadequate. Karl Fischer titration methods may give false high results because of the reducing sulfur compounds in crude oil. The present study developed an azeotropic distillation Karl Fischer coulometric titration (AD-KFCT) method which required a modified instrument and a new calibration procedure. The method was modified to decrease the interference caused by reducing sulfur compounds. A certified reference material for water content in liquid was used to determine the recovery of water mass achieved using the AD-KFCT method. The effect of the sample polarity on the method accuracy was assessed. The relative error and relative standard deviations of the water content in three crude oils containing known amounts of water were -7.5% to 2.9% and 0.4% to 6.0%, respectively. The interference by reducing sulfur compounds was studied. The crude oil containing 1-propanethiol was measured using a sulfur dioxide-free anolyte, and the amount of iodine consumed by the distilled 1-propanethiol was determined. The contribution of 1-propanethiol was then subtracted from the water content measured using the normal Karl Fischer reagent. Finally, the relative error of the modified water content in the crude oil samples containing 1-propanethiol was -4.4% to 0.7%. Therefore, the modified AD-KFCT method is accurate and convenient for crude oil.

Study on ultrasound-assisted oxidative desulfurization for crude oil.

The existence of sulfur compounds in crude oil will bring many problems such as corrosion, catalyst poisoning and pollution to the petroleum processing process. Therefore, how to reduce the sulfur content as much as possible in the process of crude oil processing has become an important research topic in the petroleum processing industry. In this paper, ultrasonic-oxidative desulfurization is studied. The effects of reaction temperature, reaction time, amount of oxidant and demulsifier on desulfurization rate are investigated. And the effect of oxidative desulfurization and single oxidative desulfurization under ultrasonic treatment are compared. It is found that the addition of ultrasonic treatment can enhance the desulfurization effect of desulfurizer, the desulfurization efficiency can be increased by about 10% under ultrasonic treatment (100W, 70kHz); ultrasonic wave plays an auxiliary role in the system, it can promote heterogeneous reactions, improve the activity of oxidants, and promote the degradation of macromolecular compounds. Finally, physical desulfurization, chemical desulfurization and biological desulfurization technologies are compared.

Organic Geochemically Significant High-Molecular-Mass Sulfur Compounds of North African Crude Oils

Fourier transform ion cyclotron resonance mass spectrometry was applied to the analysis of the complex distribution of sulfur compounds of North African crude oils. The sulfur compound distribution fingerprints were used for the characterization of crude oils from the Gulf of Suez and Western Desert of Egypt. Because a mass spectrometric technique was involved, the information supplied by high-molecular-mass sulfur compounds could be collected, in contrast to previous attempts that mainly used gas chromatography and low-molecular-mass sulfur compounds. The results showed large variations in the distribution of sulfur compounds in crude oils of different sources. The high relative abundance of double bond equivalent (DBE) of 6, the benzothiophene series, is associated with oil from a carbonate source rock, while a fairly equal DBE distribution was observed in a siliciclastic crude oil. A newly proposed parameter ∑DBEs/DBE of 6 is proposed and was found to be sensitive to changes in thermal maturity and cor...

Dual-stage acid gas combustion to increase sulfur recovery and decrease the number of catalytic units in sulfur recovery units

Sulfur compounds in crude oil and gas are absorbed as acid gas (H2S and CO2), and converted to sulfur in sulfur recovery units (SRUs). To meet environmental standards, SRUs must achieve sulfur recovery efficiency (SRE) near 98–99.99%. The existing technologies for high SRE induce high costs to the economically deficient SRUs. To reduce their operating cost, a process modification is proposed that increases SRE and reduces the number of expensive catalytic units. The modification involves dual-stage acid gas combustion occurring in two Claus furnaces along with the intermediate withdrawal of sulfur and H2O. The conventional and the modified thermal sections are simulated using industrial plant data and a detailed reaction mechanism. The SRE in the thermal section increased from 63% with the conventional process to 75% with the modified process. To determine the overall efficiency, the 2-stage and 3-stage catalytic units combined with the conventional and modified thermal sections are simulated. The overall SRE of the modified thermal section with 2-stage catalytic unit was higher than that of the conventional thermal section with 3-stage catalytic unit, which indicates that the number of catalytic units and the operating cost of SRUs can be reduced with the suggested process modifications.

Investigations in enhancement biodesulfurization of model compounds by ultrasound pre-oxidation

In this study, complicated model sulfur compounds in crude oil were biodesulfurized in a batch process by microbial consortium enriched from oil contaminated soil. Dibenzothiophene (DBT) was selected as model sulfur compounds. Ultrasonic radiation was used to pre-oxidize the model sulfur compounds before the biodesulfurization (BDS) process. The enhancement mechanism of ultrasound pre-oxidation (UPO) on the biodesulfurization of DBT was investigated. The effects of initial conditions on the biodesulfurization of DBT in UPO/BDS system such as solution initial pH, DBT initial concentration, sulfur source, biocatalyst initial concentration, and incubation temperature were discussed. The results show that the application of UPO before BDS procedure significantly improved the efficiency of the biodesulfurization and allowed sulfur removal in shorter time through oxidizing DBT to DBT sulfone, resulting in shortening the “4S” pathway for biodesulfurization from 4 steps to 2 steps, enhancement in reaction velocity and enzyme-substrate affinity as well as reduction in substrate inhibition. The concentration of 2-HBP increased fast with the use of ultrasound pre-oxidation, which was dependent on solution initial pH, DBT initial concentration, sulfur source, biocatalyst initial concentration, and incubation temperature.

Quantitative and Qualitative Analysis of Three Classes of Sulfur Compounds in Crude Oil.

Owing to the environmental hazards arising from sulfur-containing combustion products, strong legal regulations exist to reduce the sulfur content of transportation fuels down to a few ppm. With the ongoing depletion of low-sulfur crude oil reservoirs, increased technological efforts are needed for crude oil refining to meet these requirements. The desulfurization step is a critical part of the refining process but partly suffers from the recalcitrance of certain species to sulfur removal and the inability to quantitatively understand the behavior of individual compound classes during the process. We herein present a new and simple approach for the parallel quantification of three different classes of sulfur species present in crude oils by LC separation and on-line detection and quantification by ICP-MS/MS. This approach will help to estimate the amount of recalcitrant species and thus facilitate the optimization of desulfurization conditions during fuel production.

Structural Assignments of Sulfur-Containing Compounds in Crude Oil Using Ion Mobility Spectrometry-Mass Spectrometry

Through proof-of-concept experiments, a preliminary structural characterization of isomeric and isobaric sulfur-containing compounds in petroleum is presented. Silver attachment to sulfur atom has been used for ionization enhancement of these compounds, which are less accessible by positive-ion electrospray ionization mass spectrometry (ESI-MS). Here, ion mobility spectrometry (IMS) is combined with the enhanced ionization approach and MS to characterize sulfur compounds in crude oil. The silver isotopes, being of nearly equal abundance and having a similar effect upon ion mobilities, provide a fingerprint for assignments of sulfur-containing ions in two-dimensional (2D) plots of mass-to-charge (m/z) vs drift time (tD). Fourier transform ion cyclotron resonance (FT-ICR) MS has been employed for the determination of molecular formulas for these ions. Collision-induced dissociation (CID) data are utilized to complement collision cross section (CCS) comparisons for candidate structures obtained from high mas...

Separation and Characterization of Reactive and Non-Reactive Sulfur in Petroleum and Its Fractions

We present an efficient, easy-to-use chromatographic method to separate reactive and nonreactive sulfur compounds in crude oil for subsequent quantitative analysis and molecular characterization. Sulfur compounds in petroleum samples are separated by ligand exchange chromatography (LEC) on a silver-modified strong-cation exchange (SCX) solid-phase extraction (SPE) cartridge. LEC separation takes advantage of the bonding affinity of different sulfur types with silver-cations. The elution of a particular sulfur type (reactive or nonreactive) depends on the “strength” of the solvent used. One solvent mixture elutes nonreactive sulfur compounds (thiophenics and diaryl sulfides) into the first fraction. A second solvent mixture elutes reactive S-compounds (sulfides and disulfides) into the second fraction. A third reactive sulfur class (thiols) irreversibly reacts with the impregnated silver-ion to form silver thiolates that are insoluble in the solvent mixtures employed. The distribution of reactive and nonre...

Application of liquid-phase microextraction for the determination of sulfur compounds in crude oil and diesel

A liquid-phase microextraction (LPME) method was for the first time developed for the determination of sulfur compounds in Arabian crude oil and diesel. A wide range of sulfur compounds, which included benzothiophene, dibenzothiophene and their derivatives, was used for model compounds. The analyses were performed by a gas chromatography equipped with a sulfur chemiluminescence detector (GC-SCD). Under optimum conditions, a linearity was achieved for the extraction sulfur compounds between 0.10 and 250μgmL−1 with the correlation of determination ranging from 0.98 to 0.99. Applying the same optimum conditions, the extraction of 77–91% of the sulfur compounds in the Arabian light, Arabian medium and Arabian heavy, and diesel was achieved.

Metal complex catalysts for oxidative demercaptanization of sulfur compounds in crude oil

Demercaptanization of sulfur compounds in crude oil in the presence of metal complex oxidation catalysts was studied. The adsorption capacities of the catalysts and industrial mercaptane scavengers were compared. The possibility of using these catalysts for the removal of light sulfur impurities in the field oil preparation was shown.

Sulfur compounds in crude oils of the Jurassic-Paleozoic play in Western Siberia

The composition and structure of sulfur compounds in low-, medium-, and high-sulfur crude oils from the Jurassic-Paleozoic play of Western Siberia have been studied. It has been shown that the distribution of organic sulfur compounds in the oils is determined by the depositional environment of source organic matter. Highly alkylated dibenzothiophenes (up to 15 carbon atoms in the aliphatic chain), naphthobenzothiophene isomers and their C1 and C2 homologues, and the α-n-alkylthiolane and α-n-alkylthiane homologous series have been identified for the first time among sulfur compounds of Western Siberia crude oils.

Massive dominance of Epsilonproteobacteria in formation waters from a Canadian oil sands reservoir containing severely biodegraded oil

SummaryThe subsurface microbiology of an Athabasca oil sands reservoir in western Canada containing severely biodegraded oil was investigated by combining 16S rRNA gene- and polar lipid-based analyses of reservoir formation water with geochemical analyses of the crude oil and formation water. Biomass was filtered from formation water, DNA was extracted using two different methods, and 16S rRNA gene fragments were amplified with several different primer pairs prior to cloning and sequencing or community fingerprinting by denaturing gradient gel electrophoresis (DGGE). Similar results were obtained irrespective of the DNA extraction method or primers used. Archaeal libraries were dominated by Methanomicrobiales (410 of 414 total sequences formed a dominant phylotype affiliated with a Methanoregula sp.), consistent with the proposed dominant role of CO2-reducing methanogens in crude oil biodegradation. In two bacterial 16S rRNA clone libraries generated with different primer pairs, > 99% and 100% of the sequences were affiliated with Epsilonproteobacteria (n = 382 and 72 total clones respectively). This massive dominance of Epsilonproteobacteria sequences was again obtained in a third library (99% of sequences; n = 96 clones) using a third universal bacterial primer pair (inosine-341f and 1492r). Sequencing of bands from DGGE profiles and intact polar lipid analyses were in accordance with the bacterial clone library results. Epsilonproteobacterial OTUs were affiliated with Sulfuricurvum, Arcobacter and Sulfurospirillum spp. detected in other oil field habitats. The dominant organism revealed by the bacterial libraries (87% of all sequences) is a close relative of Sulfuricurvum kujiense – an organism capable of oxidizing reduced sulfur compounds in crude oil. Geochemical analysis of organic extracts from bitumen at different reservoir depths down to the oil water transition zone of these oil sands indicated active biodegradation of dibenzothiophenes, and stable sulfur isotope ratios for elemental sulfur and sulfate in formation waters were indicative of anaerobic oxidation of sulfur compounds. Microbial desulfurization of crude oil may be an important metabolism for Epsilonproteobacteria indigenous to oil reservoirs with elevated sulfur content and may explain their prevalence in formation waters from highly biodegraded petroleum systems.

AN EXPERIMENTAL APPROACH OF ELEMENTAL SULFUR DEPOSITION IN CARBONATE OIL RESERVOIRS

ABSTRACT The existence of sulfur compounds in crude oils creates many problems of sulfur deposition in the vicinity of the wellbore hole, in well completion and/or production equipment, and in producing reservoir rocks. The major objectives of this experimental study are to investigate the influences of oil flow rate, initial sulfur concentration of crude oil, and reservoir rock permeability on elemental sulfur plugging in carbonate oil reservoirs. To achieve these objectives, actual crude oils were de-asphaltened to eliminate the effect of asphaltene deposition. Ten dynamic flow experiments were conducted using two actual crude oils of 0.78 and 1.67% sulfur concentrations. Viscosity of crude oils of different sulfur concentrations was measured under different conditions of temperature. The crude oils were flooded through actual carbonate cores of different permeability in the range of 2.34–28.16 millidarcy and under different flow rates of 0.5, 1.0, 1.5, and 2.0 cc/min. In-situ sulfur deposited was measured using Scanning Electron Microscopy (SEM) to provide the amount of sulfur deposited along the core samples. The results indicated that crude oil of higher sulfur concentration has higher viscosity than that of one of lower concentration. The deposition of elemental sulfur does not take place at the low rate of 0.50 cc/min, starts at 1.0 cc/min and increases as the flow rate increases up to 1.50 and 2.00 cc/min, respectively. In addition, the higher sulfur concentration of the crude oil increases the deposition of sulfur in carbonate oil reservoirs. The results also showed that permeability of carbonate reservoir rocks has a severe effect on sulfur deposition since carbonate rocks of higher permeability do not experience the problem of elemental sulfur deposition while the problem is more severe for lower permeability rocks. In addition, the depositional rate is accelerated rapidly as the rock permeability decreases. The obtained results of this study have important interest in identification of the most important factors affecting the elemental sulfur precipitation in heterogeneous carbonate oil reservoirs and robust implications in the development of reservoir simulation models.

Chemical and engineering corrosion protection for equipment in the EDU: AVT plant

The chlorides (both inorganic and organic) and sulfur compounds in crude oil entering a refinery corrode the equipment, primarily condensers and coolers, due to their hydrolysis and cracking during primary distillation of the crude oil. The process stability of the units decreases as a result, and this does not allow increasing the interrepair periods and increases the cost of repair work.

Organic sulfur compounds in crude oils of West Kazakhstan

This article reports on a study of the distribution of organic sulfur compounds (mercaptans, disulfides, and sulfides) in crude oils and in 50/sup 0/C cuts, and also in gas condensates. Notes that the crude oils of West Kazakhstan, particularly the field that have been discovered recently, are extremely diverse in physiochemical properties, particularly in their content and structure of organic sulfur compounds. The oils from the Tortai, Kultuk and Zhilankabak fields are classified as low-sulfur (total sulfur contents 0.22%, 0.44%, and 0.47%, respectively). Investigates the group composition of condensates from the Gremyachinsk, East Gremyachinsk, West Teplovsk, and Karachaganak fields are also investigated.

Oxydativer Abbau von Dibenzylsulfid

AbstractDibenzylsulfid (DBS) as a model of the organic sulfur compounds in crude oil was converted by a mixed culture (containing Pseudomonas aeruginosa) into several water soluble organic substances. Whereas these compounds are detectable with DC‐ and IR‐spectroscopi°C techniques, benzylmercaptoacetic acid (BMA) was the only isolated product of DBS utilization. Efficiency of degradation, respectively, accumulation of BMA were dependent on aeration and pH‐regulation.

Oxidative degradation of dibenzylsulfide

Dibenzylsulfid (DBS) as a model of the organic sulfur compounds in crude oil was converted by a mixed culture (containing Pseudomonas aeruginosa) into several water soluble organic substances. Whereas these compounds are detectable with DC- and IR-spectroscopic techniques, benzylmercaptoacetic acid (BMA) was the only isolated product of DBS utilization. Efficiency of degradation, respectively, accumulation of BMA were dependent on aeration and pH-regulation.

Evolution of Sulfur Compounds in Crude Oils

An understanding of the evolution of sulfur compounds in oils may allow petroleum geochemists to direct exploration toward low-sulfur crudes. Knowing the types and chemistry of sulfur compounds is important because (1) some degrade refining catalysts, (2) others produce excessive corrosion, and (3) clean-air requirements necessitate reduction of overall sulfur levels. Seventy-eight crudes from many of the world's major fields which represent reservoirs of Cambrian to Pliocene age were analyzed and then grouped into three categories on the basis of the relative amounts and chemical stability of different sulfur-compound types. These groupings are consistent with geochemical concepts of thermal maturation and biodegradation. One group has abundant unstable sulfur compounds uch as nonthiophenic sulfides and benzothiophenes; we call this immature. Another contains more of the stable benzothiophenes and we call it mature, whereas the third has intermediate distributions which we term altered. Most of the sulfur (particularly in high-sulfur oils) is introduced secondarily by reaction of hydrocarbons with sulfur or hydrogen sulfide (both generated by the microbial utilization of hydrocarbons and sulfates in rocks). This forms a crude rich in nonthiophenic sulfides and occurs primarily during the early diagenesis of the organic matter in the source; with increasing maturation, sulfur is removed preferentially, forming a mature oil with relatively more thiophenes. At shallow depths, alteration produces crudes with more nonthiophenic sulfides and benzothiophenes. nother form of altered oils is adjacent to zones of organic metamorphism where H2S reacts with oils to produce extremely corrosive mercaptan-rich crudes and condensates. These concepts can be applied to the specifics of petroleum-exploration geochemistry.

Separation of Organic Sulfur Compounds by Liquid Thermal Diffusion

For separating and identifying sulfur compounds in crude oils, liquid thermal diffusion was investigated. The process was applied to some 50 binary mixtures of pure compounds as well as to sulfur-containing petroleum distillates. Both batch and continuous operations were studied. Liquid thermal diffusion will separate most sulfur compounds of different types from each other and from hydrocarbons, some with greater efficiency than others. Some instances of no separation were found. Continuous operation of thermal diffusion columns offers possibilities of sulfur-compound concentration from petroleum distillates. Batch operation should prove useful in separating special concentrates from distillates.