Non-aromatic Hydrocarbons Research Articles

Hydrocarbons in Seawater and Water Extract of Jarzouna-Bizerte Coastal of Tunisia (Mediterranean Sea): Petroleum Origin Investigation Around Refinery Rejection Place

We investigated the composition and spatial distribution of non-aromatic, aromatic and polycyclic aromatic hydrocarbons (PAH) found in seawater and water extracted from refinery rejection effluents in the coastal area of Jarzouna, Tunisia. Water samples were analysed for hydrocarbons by gas chromatography. Total hydrocarbon levels ranged between 46 and 76 mg/L in seawater samples and between 28 and 102 mg/L in water extracts. The sites nearest to the oil refinery were found to be chronically contaminated by total petroleum hydrocarbons based on aliphatic biomarkers. PAH contamination is generally much more pyrolytic than petrogenic. This study helped to determine the concentration, spatial distribution, compound profiles and possible sources of various petroleum compounds, thus contributing significantly to a greater understanding of the background of petroleum hydrocarbon levels, the various types of anthropogenic input involved and the contribution of the Societe Tunisienne des Industries de Raffinage refinery’s effluents in terms of hydrocarbon pollution.

Hydrocarbon pollution of the Mediterranean coastline of Morocco

Organic geochemical study of hydrocarbon pollution of the Mediterranean coastline of Morocco (Tangier-Nador) was performed during March–April 2002. It corresponds to a preliminary work representing an initial assessment of oil contamination of Moroccan coast. Three coastal sites corresponding to Tangier, Tetouan and Nador, representing the main built-up area of this marine region, were selected for superficial sediments, water and organism sampling. Results showed high contamination levels in these three selected sites, known as the most exposed areas to urban and industrial discharges. The maximal contamination corresponding to the sum of non-aromatic (NAH) and polycyclic aromatic hydrocarbons (PAH) encountered in sediment samples was about 553 μg/g (dw). Nevertheless, even a small city agglomeration without any industrial activity showed high values reaching 370 μg/g (dw), which confirm the important hydrocarbons input coming from discharges of fishing ships and oil transporting tankers. The obtained results from this survey reflecting in part the important amounts drained via effluents toward the Moroccan Mediterranean coasts, presented to the concerned authorities drove to the realization of the project of treatment of the wastewater. They later expect to lower rates by 50%, which is still insufficient for a fragile ecosystem such as the Mediterranean and sensitive to anthropogenic effects.

Self-assembled organogels based on two-component system

Organogels were produced by the self-assembly of two organogelators, 3,5-bis(dodecanoylamino)benzoic acid and aromatic amines, in nonaromatic hydrocarbon solvents, through hydrogen bonding, aromatic stacking, and van der Waals interactions. 3,5-Bis(dodecanoylamino)benzoic acid has one carboxylic acid group for hydrogen bonding with amines and two alkylamide groups that can participate in interlayer hydrogen bonding and van der Waals interactions. The shape and size of the aromatic amines have a significant effect on the gel properties as well as their structures. A variety of organogels were realized by forming complexes of 3,5-bis(dodecanoylamino)benzoic acid and various amines with an aromatic group in nonaromatic hydrocarbon solvents.

Petroleum pollution in surface sediments of Daya Bay, South China, revealed by chemical fingerprinting of aliphatic and alicyclic hydrocarbons

Nine surface sediments collected from Daya Bay have been Soxhlet-extracted with 2:1 (v/v) dichloromethane-methanol. The non-aromatic hydrocarbon (NAH) fraction of solvent extractable organic matter (EOM) and some bulk geochemical parameters have been analyzed to determine petroleum pollution of the bay. The NAH content varies from 32 to 276 μg g −1 (average 104 μg g −1) dry sediment and accounts for 5.8–64.1% (average 41.6%) of the EOM. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and petrogenic sources in varying proportions. The contribution of marine authigenic input to the sedimentary n-alkanes is lower than the allochthonous input based on the average n-C 31/ n-C 19 alkane ratio. 25.6–46.5% of the n-alkanes, with a mean of 35.6%, are contributed by vascular plant wax. Results of unresolved complex mixture, isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. There is strong evidence of a common petroleum contamination source in the bay.

Characterization of products from the pyrolysis of rapeseed oil cake

The main aim of this study was to investigate the composition of products from the pyrolysis of rapeseed oil cake in a fixed bed reactor at 400, 450, 500, 700 and 900 °C. The gas products mainly consisted of CO 2, CO, CH 4 and H 2S at 500 °C. Empirical formula of bio-oil from the pyrolysis of rapeseed oil cake was CH 1.59O 0.16N 0.116S 0.003 for 500 °C. Bio-oils mainly contained oleic acid, 1 H-indole, 2,3,5-trimethoxy toluene, toluene, ( Z)-9-octadecanamide, psoralene, phenol and phenol derivatives at all pyrolysis temperatures. Both non-aromatic and aromatic hydrocarbon compounds were determined in water phase of liquid product by Headspace-GC analysis. The heating values of bio-chars were found to be similar (24 MJ kg −1) at all pyrolysis temperatures.

Novel Micropyrolyis Index (MPI) to Estimate the Sooting Tendency of Fuels

A new fuel quality indicator called micropyrolysis index (MPI) is proposed for quantifying sooting tendencies of fuels in research laboratories. The MPI has been designed with the following characteristics: (i) oxygen independence, since sooting tendencies can change dramatically with varying oxygen concentration, (ii) reduced sample volume that can be utilized on a laboratory scale, (iii) improved repeatability over traditional methods, and (iv) use of common laboratory equipment so that the method may easily be implemented in multiple laboratories. MPI measurements were conducted by pyrolyzing 20 µL of fuel across a bed of R-Al2O3 beads at a temperature of 850 °C. Subsequently, the carbon-containing beads were transferred to a clean reactor where the deposited carbon was burned via temperature programmed oxidation (TPO) in order to quantify the amount. The amount of deposited carbon provides an indication of the tendency of a particular fuel to form soot when pyrolyzed. The observed tendency is independent of operating conditions, such as flame temperature and stoichiometric oxygen/fuel ratios, which greatly affect the measurements in other techniques used to estimate sooting tendency. An MPI value of 5 was assigned to the amount of carbon deposited from n-octane, and a value of 20, to the value corresponding to decalin. These two compounds were used as reference. Repeatability tests showed that MPI measurements had a standard deviation of 1.02 MPI at MPI ) 94.7 which scaled down to 0.11 at MPI ) 3.3. MPI values of pure nonaromatic hydrocarbons were found to correlate well with traditional threshold soot index (TSI) values. However, MPI was found to be more differentiating than TSI among the different hydrocarbon families: n-alkanes, isoalkanes, and cycloalkanes. A quantitative structure-property relationship (QSPR) model was developed in order to predict the MPI of other pure compounds not measured experimentally and further expand the database. Blending issues with aromatics are discussed, as well as the effects of aromatic content in real feeds.

Hydrocarbon Pollution in the Sediment from the Jarzouna-Bizerte Coastal Area of Tunisia (Mediterranean Sea)

This study investigated the presence and origin of hydrocarbon pollution in industrial waste water sediments found near the Jarzouna (Bizerte, Tunisia) oil refinery. Analyses of surface sediments (layer 1) and deep sediments (layer 2) showed that Total Hydrocarbon (TH) concentrations ranged from 602 +/- 7.638 microg/g in layer-1 to 1270 +/- 2.176 microg/g in layer-2. The results suggest that the deeper the sediment, the higher the level of total hydrocarbon found. The sedimentary Non Aromatic Hydrocarbon (NAH) and Aromatic Hydrocarbon (AH) concentrations ranged from 66.22 +/- 1.516 to 211.82 +/- 10.670 microg/g for NAH, and from 13.84 +/- 0.180 to 115.60 +/- 2.479 microg/g for AH. The high variability of these concentrations was associated with the location of the sediment collection sites. Aliphatic biomarker analysis revealed petroleum contamination close to the refinery rejection site, and biogenic sources further away. Petroleum contamination may be associated with increased industrial activity in the area of Jarzouna-Bizerte in the Mediterranean Sea.

Composition and sources of organic matter and its solvent extractable components in surface sediments of a bay under serious anthropogenic influences: Daya Bay, China

Organic matter of nine surface sediments from the Daya Bay was Soxhlet-extracted with a mixture of 2:1 (v/v) dichloromethane–methanol and separated into five fractions: non-aromatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, and fatty acids and asphaltenes, and analyzed to determine their bulk and biomarker composition. Marine autogenic input appears to be a major source of organic matter. Generally, non-aromatic hydrocarbons are the most dominant fraction of solvent-extractable organic matter (EOM) followed by the other four fractions in decreasing amounts: fatty acids and asphaltenes, ketones, alcohols and aromatic hydrocarbons. On average, both non-aromatic hydrocarbon fraction and fatty acid and asphaltene fraction account for ∼40% of EOM. The sources of acyclic methyl ketones, alkanols and fatty acids were examined. For n-alkan-2-ones, allochthonous input is a more important source than marine autogenetic input; the reverse is true for n-fatty acids; for n-alkanols, allochthonous and autogenetic inputs seem comparable. Both n-alkan-2-ones and n-fatty acids in the surface sediments of different areas appear to be derived from common sources.

Sources of hydrocarbon pollution in surface sediments of the Campeche Sound, Gulf of Mexico, revealed by biomarker analysis

Surface sediments from the shelf area of the Campeche Sound (Gulf of Mexico) and the adjacent abyssal plain were sampled in the course of environmental monitoring for petroleum pollution as a result of industrial activity in the largest oil field in Mexico. Offshore oil production, refinery activities and heavy ship traffic, as well as natural petroleum seeps, are potential sources of pollution of water and sediment in the area. Gas chromatography–mass spectrometry (GC–MS) analysis of the nonaromatic hydrocarbon fractions of the sediment extracts revealed overlapping hydrocarbon assemblages indicating multiple sources. Samples taken close to known asphalt seeps exhibit biomarker patterns virtually identical to those of reference crude oils, so the asphalts have apparently escaped from petroleum reservoirs with fractured cap rocks. Other sediments, with distributions superimposed on mature fossil hydrocarbons, contain biomarkers typical of neither fossil fuels nor immature organic matter (OM) in marine surface sediments. They obviously derive from drill cuttings recovered during penetration of Tertiary to Cretaceous deposits and disposed of into the shallow sea, as indicated by the comparative analysis of drill cuttings from several wells in the area.

Non-aromatic hydrocarbons in recent sediments of Sepetiba and Ilha Grande Bays, Brazil

An investigation was conducted in Ilha Grande and Sepetiba Bays aiming at identifying the nature of non-aromatic hydrocarbons (NAH) in surface sediments. NAH concentrations ranged from 2.5 µg g-1 to 193.8 µg g-1 of which the major fraction (53 to 93%) was composed by unresolved complex mixture (UMC). In most samples n-alkane distribution was dominated by compounds of odd carbon number showing maxima in nC29 and nC31. Mono-olefins were at low concentrations and the polyolefins including highly branched isoprenoids and squalene varied from 0.099 µg g-1 to 1.387 µg g-1 with lower values relative to NAH appearing in areas of strong terrestrial and anthropogenic influence. Hopanes between C27 and C33 were observed in all samples with the predominant configuration 17a(H),21b(H), characteristic of a petrogenic origin.

Revisiting the organohalogens associated with 1979-samples of Brazilian bees (Eufriesea purpurata)

Brazilian bees of the species Eufriesea purpurata are known to tolerate very high concentrations of DDT. As reported in the literature, these bees have suffered no harm from as much as 2 mg/bee, which is in the per-cent range of the body weight. In 1979, individuals of E. purpurata were captured as they collected DDT from walls of remote, rural houses in Brazil. Reported herein are quantities and identities of DDT, DDT metabolites, and other organohalogen compounds in four samples of bees stored since 1979. The concentrations of DDT (sum of p,p'-DDT, -DDE, and -DDD) ranged from 23 to 314 microg/bee which is up to twelve fold higher than the LD(50) value of DDT in the honey bee (Apis mellifera) but significantly lower than the no-effect concentration in E. purpurata. Enantioselective determination confirmed the presence of racemic o,p'-DDT in the four individual samples. GC/ECNI-MS investigation resulted in the detection of low amounts (<1 microg/bee) of PCA, lindane, and chlordane. At higher retention times four unknown compounds were detected with a proposed molecular ion at m/z 498, a non-aromatic hydrocarbon backbone along with the presence of eight chlorine substituents. Neither the structure nor the origin of these compounds could be determined. Considering where and when the bees were collected and considering the biology and ecology of the euglossine bees themselves, we propose that the four unknowns are natural products and, as such, are the most highly chlorinated natural compounds yet discovered.

Non-aromatic hydrocarbons in surface sediments near the Pearl River estuary in the South China Sea

Surface sediment samples at 4 sites along an offshore transect from outer continental shelf off the Pearl River estuary to the shelf slope region of the northern South China Sea, have been analyzed for total organic carbon (TOC), total nitrogen (TN), solvent extractable organic matter (EOM) and non-aromatic hydrocarbons. TOC, TN and EOM show distinct spatial variations. Their highest values are all recorded at the shelf slope region. EOM varies from 18.70–38.58 μg g −1 dry sediment and accounts for 0.20–0.72% of the TOC contents. The non-aromatic hydrocarbons are an important fraction of EOM. Their contents range from 3.43–7.06 μg g −1 dry sediment. n-Alkanes with carbon number ranging from 15–38 are identified. They derive from both biogenic and petrogenic sources in different proportions. Results of isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination.

Sources and distribution of aliphatic and polyaromatic hydrocarbons in sediments of Sfax, Tunisia, Mediterranean Sea

This investigation is the first extensive study of the spatial distribution and sources of hydrocarbons in surface sediments from the Sfax–Kerkennah coastal zone (Tunisia). We show that the Sfax–Kerkennah coastal zone suffers from serious problems of pollution due to petroleum contamination. Analyses performed by GC/FID and GC/MS permitted a precise determination of both aliphatic and alicyclic compounds ( n-alkanes, isoprenoids, hopanes, steranes, diasteranes and unresolved complex mixture of fossil hydrocarbons and highly degraded organic matter (UCM)) and polycyclic aromatic hydrocarbons (PAHs). Non-aromatic hydrocarbon concentrations vary in the range = 16–1729 μg/g sediment d.w., and PAH concentrations vary in the range = 0.11–10.72 μg/g sediment d.w. These concentrations are relatively high, compared to other Mediterranean sites (37 examined sites). n-Alkane, UCM and PAH concentrations with biomarker profiles together prove the presence of a limited petrogenic contamination in sediments close to the Kerkennah Island, 22 km from the harbour of Sfax. In contrast, moderate to high petrogenic contamination is detected in the Sfax area sediments, notably closer to the storage tanks of hydrocarbons. Contaminant patterns indicate that PAHs originate mainly from fossil sources, with higher pyrolytic contributions near industrialized and urban areas. GC/MS analyses indicate the omnipresent contamination by petroleum. This contamination is confirmed by the identification of hopanes with predominant C 29 and C 30 α,β compounds and steranes with predominance of C 29, C 28 and C 27 compounds.

APUSM technology for the production of BTX and LPG from pyrolysis gasoline using metal promoted zeolite catalyst

SK Corporation developed an advanced pyrolysis gasoline (pygas) upgrading (APUSM) technology based on a catalytic process for producing valuable benzene, toluene and xylenes (BTX) and liquefied petroleum gas (LPG) from pygas containing aromatics and non-aromatic hydrocarbons. Hydrodealkylation of heavy aromatics and hydrocracking of non-aromatic hydrocarbons occurred with facility in the conversion of pygas over a proprietary catalyst, metal promoted zeolite. This catalytic process produced benzene and toluene with high purity corresponding to chemical grade while giving mixed xylenes with reduced ethylbenzene. In the present study, we described novel features of the APUSM technology in terms of the process and catalyst. The influence of the process conditions was also examined. This technology has been commercially proven, and hence is available for licensing through Axens, which is a major engineering and licensing company.

The roles of acidity and structure of zeolite for catalyzing toluene alkylation with methanol to xylene

A variety of zeolites, including MOR, MCM-22, SAPO-34, SAPO-11, SAPO-5 and ZSM-5 with different SiO 2/Al 2O 3 ratio, were used for catalyzing toluene alkylation with methanol to produce xylene. The catalytic activity of zeolite for the toluene alkylation is approximately proportional to the number of its mid-strength acidic sites, except for SAPO-34 with small channels and MOR with strong acidity. Moreover, the acidic sites for catalyzing toluene alkylation are weaker in strength than those for catalyzing toluene disproportionation, but slightly stronger than those for catalyzing the reaction of methanol to hydrocarbons. On the other hand, zeolites with 12-membered ring channels may lead to the further alkylation of xylene and the rapid deactivation by coking. Zeolites with 8-membered ring channels restrict toluene alkylation, only favorable for forming non-aromatic hydrocarbons. As a result, zeolites with 10-membered ring channels and mid-strength acidity show high catalytic selectivity and activity for methylation of toluene.

Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea

The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world’s ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310–1406 μg g −1 sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C 29 and C 30 α,β compounds and steranes with predominance of C 27 over C 28 and C 29 compounds.

Potential energy surfaces in Coulomb explosion of polyatomic molecules: Benzene and cyclohexane trications and acetylene dication

AbstractWe report density functional and ab initio calculations of potential energy surfaces (PES) for benzene and cyclohexane trications relevant to the Coulomb explosion mechanisms of C6H6 and C6H12. Numerous isomerization and dissociation mechanisms on these PES have been considered, and the products most favorable thermodynamically and kinetically have been predicted. We also demonstrate applications of RRKM theory to the calculation of product branching ratios in decomposition of multiply charged cations. Significant common features of PES related to Coulomb explosion experiments on hydrocarbon molecules have been described. Calculations along minimal energy reaction paths for some representative isomerization and dissociation channels have been carried out in the presence of strong external electric field for C6H and C2H and the influence of the field on molecular orientation and PES have been analyzed. The results show that proton mobility in nonaromatic hydrocarbon cations is high due to nearly zero barriers for the H+ migrations. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Organic matter in a low productivity anoxic intraplatform basin in the Triassic Tethys

This paper presents isotopic, bulk geochemical and biomarker data measured on organic matter accumulated in a narrow extensional basin developed at the oceanward margin of the huge Triassic carbonate platform in the Alps–Appenines domain. The integration of isotope signatures, organic petrographical and biomarker evidence together with the composition of kerogen pyrolysates suggests immature organic matter predominantly of algal origin with a minor, but not negligible, higher plant derived and moderate bacterial contribution for the entire sequence. The mineral sources are dominated by platform-derived subtidal Dachstein limestone with a minor palaeosol input and a moderate contribution of autochtonous quartz. Nevertheless, parallel variations observed in the mineral content, as well as in the amount and the quality of the organic matter reflect variations in the palaeoenvironment. The increased humidity, existing in the period of the accumulation of the upper section of the sequence, led to the restriction of dolomitization. A slightly greater higher plant derived contribution, in this section, is evidenced by the composition of bitumen and the results on GC and GC/MS analyses on the non-aromatic hydrocarbon fraction of bitumen. Moreover, the climate-induced weathering enchanced the primary productivity and resulted in a pronounced increase in the TOC content. The average estimated value of the planktonic productivity is about three times higher for the calcite-rich sequence than the dolomite-rich one, being 44.2 and 15.3 tC org/m 2/Ma, respectively. The low to moderate planktonic productivity shows that anoxic conditions, observed for the entire succession, are a consequence of the stagnant water stratification rather than high planktonic productivity. Depth trends in the data measured on kerogens (HI, OI, δ 13Corg values, composition of pyrolysate) together with the δ 18O excursions and Δ δ 13C values appear to be controlled by sea-level fluctuations. Consistent with the high abundance of alkyltiophenes in kerogen pyrolysates, the high S org/C ratios (ranging between 0.05 and 0.10) suggest the importance of natural sulfurization in the formation of the sulfur-rich type-II-S kerogen occurring in all of the samples.

Aqueous Solubility and Related Thermodynamic Functions of Nonaromatic Hydrocarbons as a Function of Molecular Structure

The aqueous solubilities of several C8 nonaromatic hydrocarbons differing in their molecular structure (cyclooctane, cyclooctene, ethylcyclohexane, cis- and trans-1,2-dimethylcyclohexane, 2,2-dimethylhexane, and 2,5-dimethylhexane) were studied at temperatures between 274 and 313 K using a dynamic saturation column method. The resulting experimental values had an estimated uncertainty between 5 and 10%. Their correlation as a function of temperature allowed the determination of the enthalpy and heat capacity change characterizing the dissolution process. A combination with the data on pure solutes selected from the literature made it possible to calculate Henry's law constants and the air−water partition coefficients as well as the thermodynamic functions of hydration. These different data were combined with information from the literature and analyzed with respect to the molecular structure of aqueous hydrocarbons. A simple group contribution concept was found to be useful for rationalizing the evolution...

Application of coupled TG-FTIR system in studies of thermal stability of manganese(II) complexes with amino acids.

Detailed thermal analysis of manganese(II) complexes with a-amino acids were carried out. The thermal degradation is multi-stage. Dehydration of complexes is the first mass loss step. Anhydrous compounds are unstable and decompose to Mn3O4 in air or to MnO in inert atmosphere. The intermediate solid products were identified by TG method and TG/FTIR combined technique. Among others solid residues, the presence of MnSO4, MnBr2 and Mn(CH3COO)Cl was found. In the gaseous products of decomposition of organic ligand H2O, NH3, CO2, CO, aromatic and non-aromatic hydrocarbons and very probably cyanoacetic acid and dimethyl sulfide occurred. Inorganic ions, i.e. Cl-, Br-or So42-remain in the solid products of decomposition or are lost as HCl, HBr or SO2.