Evolution Of Hydrocarbons Research Articles

Oil and gas evolution kinetics for oil shale and petroleum source rocks determined from pyrolysis-TQMS data at two heating rates

Seven oil shales and petroleum source rocks were subjected to programmed-temperature pyrolysis at heating rates of 1 and 10°C/min using triple-quadrupole mass spectrometry to monitor volatile compound evolution. Kinetic parameters were determined for evolution of hydrocarbons and various heteroatom species. Normalized cumulative generation of oil, light hydrocarbon gas (C 2 -C 4 ), methane, carbon dioxide, acetic acid, hydrogen sulfide, and methylthiophene were calculated for generic geologic conditions using kinetic parameters that were lumped and averaged into type I, IIa, and IIb source rock classes. The four heteroatom species are largely generated before oil and the hydrocarbon gases. Using these kinetics to simulate hydrous pyrolysis gives favorable comparison with hydrous pyrolysis measurement of acetic acid generation for several different source rocks

Biogenic aromatic hydrocarbon geochemistry in the Rhone river delta and in surface sediments from the open North-Western Mediterranean sea

The origin, evolution and transport of biogenic polycyclic aromatic hydrocarbons (PAH) were studied in the Rhone river delta and the Gulf of Lions (North-western Mediterranean). Sediments and riverborne suspended particulate matter were collected and analysed for PAH using a combination of high performance liquid chromatography (HPLC), gas chromatography (GC) and GC/mass spectrometry (GC/MS). Special attention was given to aromatic hydrocarbons from natural sources: retene and its precursors related to abietic acid found in the resins of conifers, and pentacyclic triterpenoids derived from α - and β -amyrins, constituents of terrestrial plants. Retene concentrations varied in the following ranges: 15–59 ng g −1 in river-borne particulate material, 20–70 ng g −1 in deltaic sediments, 3–16 ng g −1 in open-sea sediments. Retene precursor concentrations were generally higher than those of retene in the delta, whereas the inverse was observed in open-sea sediments. In these sediments the low concentrations or the absence of precursors suggested a predominant transport of pre-formed retene by aerosols and fine particles issued from the Rhone river. In the deltaic area, both retene and its precursors are transported by river waters from the forest runoff of the drainage basin. Transformation of precursors to retene occurred during transport by river waters and/or fast after deposition in surface deltaic sediments. Pentacyclic triterpenoid concentrations varied from 54 to 296 ng g −1 in deltaic sediments and from 0 to 21 ng g −1 in open-sea sediments. Concentrations of tetrahydrochrysenes (3,3,7-THC and 3,4,7-THC) decreased with increasing distance from the Rhone river mouth. The presence of THC in the riverine particulate matter (10–105 ng g −1 ) indicated that the degradation of terrestrial organic matter by microbial activity had begun before the deposition of particulate matter in the surface sediment. A good correlation was observed between ΣTHC and δ 13 C ( r 2 = 0·89; n = 9), which suggests that the THC tracer information was representative of natural continental organic carbon inputs.

Evolution of individual hydrocarbons (C 1C 4) by nonisothermal pyrolysis of petroleum source rocks

Nonisothermal pyrolysis of Toarcian oil shales from the Hils Syncline area, conducted at a low heating rate of 0.1°C/min, resulted in evolution profiles of individual alkanes (C 1C 4) and alkenes (C 2C 4) from which kinetic parameters and amounts of hydrocarbons were derived. The immature ( R m=0.48%) shale sample displayed at least four methane-generation reactions. The activation energies assessed by simple nonisothermal kinetics for the generation of alkanes (C 1C 4) and alkenes (C 2C 4) increased with increasing maturity of the shales, with the position of the maximum dependent on the individual hydrocarbon. Increasing shale maturity appeared to promote alkane and alkene formation.

Rotary kiln incineration. Comparison and scaling of field-scale and pilot-scale contaminant evolution rates from sorbent beds

A comparison is made, for the first time, between the evolution of hydrocarbons from clay sorbent beds in a field-scale rotary kiln incinerator and in a pilot-scale rotary kiln simulator. To relate the data from the different sized units, due allowance is made for bed dynamical similitude, bed geometrical factors, and bed heat-up. To minimize the effects of disturbances caused by foreign matter in the field-scale bed and differences in loading techniques, the rate of evolution is characterized by an evolution interval defined as the time required for the middle 80% of the ultimate contaminant evolution to occur. A comparison of evolution intervals with reciprocal bed temperature reveals that the data are consistent with an analysis that assumes a uniform bed temperature (at any instant of time) and a desorption-controlled evolution rate. Furthermore, the evolution intervals scale inversely with a modified Froude number, which characterizes bed dynamics. The success in comparing field and simulator results indicates that pilot-scale rotary kilns may be used to simulate certain features of industrial-scale units if dynamical, geometrical, and thermal parameters are matched appropriately.

硫酸クロム（ＩＩＩ）‐シュウ酸アンモニウム浴からの非晶質Ｃｒ‐Ｃ合金めっき

The carbon contents in Cr-C deposits obtained from Cr (III) sulfate-ammonium oxalate baths changed from 0.8wt% up to 3.2wt% with increases in the oxalate concentration in the bath. The structure of the deposits changed from crystalline to amorphous at a carbon content of about 1.4wt%. With the heating of amorphous Cr-C alloy two exothermic reactions occurred-one at 250∼350°C due to crystallization of metallic Cr from the amorphous alloy, and the other at 610∼630°C due to the deposition of Cr7C3 in the Cr metal matrix. The Cr-C deposition and the evolution of hydrocarbon at cathode seem to be brought about by the reduction of oxalate to carbon on the electrode surface during Cr electrodeposition.

Gafsa Trough of Central Tunisia: Basin Evolution and Maturation of Hydrocarbons

The Gafsa trough of onshore central Tunisia is one of the more interesting and underexplored features of North Africa. It is a 5-12 km deep, east-west-trending depression along the inner edge of the Tunisian-Libyan shelf margin. The basin has had a long and virtually uninterrupted history of subsidence from the late Paleozoic into the early Cenozoic. Subsidence began in the late Carboniferous, soon after the close of the Hercynian orogeny, and resulted in deposition of a 3000+ m succession of Permo-Carboniferous carbonates and shale that pinches out southward onto the Saharan Flexure. The tectonic setting for this earliest phase of subsidence is not clear. The main episode of subsidence, which began in the Middle Triassic, continued through the Jurassic as left-lateral, transtensional rifting along the South Saharan and Maghrebian Shear zones. A set of organic maturation maps for onshore central Tunisia depicts the minimum time of entry into the oil and gas generative windows of the two potential source rocks in the region, the Lower Silurian Tannezufft Formation and Middle-Upper Jurassic basinal shales. Maturation modeling suggests that the Lower Silurian source rocks beneath the deeper portions of the Gafsa trough are overmature, even for generation of dry gas. Everywhere northmore » of the Saharan Flexure potential Paleozoic source rocks are highly mature to overmature. The Middle-Upper Jurassic basinal shales in the deeper, central portions of the Gafsa trough entered the oil generative window as early as mid-cretaceous time and into the gas generative window in the Late Cretaceous - early Tertiary. These possible source rocks are mature to highly mature beneath nearly all of the basin. The Gafsa trough is a probable gas province, with occurrences of condensate possible.« less

Protonation of trans-[Mo(C2H4)2(Ph2PCH2CH2PPh2)2]: sites of protonation and factors influencing the formation of ethane and ethylene

The mechanism of the formation of ethane and ethylene in the reactions of trans-[Mo(C2H4)2(dppe)2](dppe = Ph2PCH2CH2PPh2) with HX (X = Cl or Br) in tetrahydrofuran at 25.0 °C has been established by a combination of stopped-flow spectrophotometry, detailed product analysis and kinetic investigation of the evolution of hydrocarbons, together with characterisation of the key intermediates by multinuclear NMR spectroscopy. Addition of anhydrous HX to trans-[Mo(C2H4)2(dppe)2] rapidly generates [MoH(C2H4)(dppe)2]+ by two pathways: direct protonation at the metal or protonation at the ethylene ligand to form [Mo(C2H5)(C2H4)(dppe)2]+ followed by migration of a β-hydrogen atom from the ethyl ligand to the metal. This migration step is reversible and at low concentrations of HCl [Mo(C2H5)(C2H4)(dppe)2]+ slowly loses ethylene. Subsequent binding of chloride ultimately results in the formation of ethane, and trans-[MoCl2(dppe)2]. At higher concentrations of HCl further protonation of [MoH(C2H4)2(dppe)2]+ occurs and [MoH2(C2H4)2(dppe)2]2+ is the dominant solution species which loses both ethylene ligands to form [MoH2Cl2(dppe)2]. Quantitative analysis of the hydrocarbon product distribution at various concentrations of HCl confirms the nature of these pathways under an atmosphere of dinitrogen or argon. In the presence of carbon monoxide or dihydrogen the hydrocarbon product distribution is different. The relevance of these studies to the understanding of the different substrate specificities of the molybdenum- and vanadium-based nitrogenases is discussed, as are the factors influencing the rates of protonation of the metal in [ML2(dppe)2](M = Mo or W; L = N2, C2H4 or 2 H).

Regional Paleogeographic Evolution of West Africa: Implications for Hydrocarbon Exploration

New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. Five regional provinces are delineated: (1) Northwest Africa margin from mauritania to Sierra Leone, (2) Transform margin from Liberia to Benin, (3) Niger delta of Nigeria, Cameroon, and Equatorial Guinea, (4) South Atlantic Salt basin margin from Cameroon to Angola, and (5) Southwest Africa margin of Namibia and South Africa. Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Africa from South and North America during the Late Triassic to the present along three rift systems. In northwest Africa rifting began in the Late Triassic associated with the opening of the Central Atlantic. In southwest Africa rifting began between the southern tips of Africa and South America in the Early Cretaceous (Valanginian) and propagated northward to the Benue Trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the Transform margin rift system initiated in the Early Cretaceous (Barremain) as a wrench-fault dominated eastward extension of the Proto-Caribbean ocean that propagated to the Benue Trough by the middle Albian. The most important variables affectingmore » the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting; (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land); (3) sea-level fluctuations; and (4) distribution of deltaic and turbiditic depocenters.« less

Formaldehyde decomposition and oxidation on Pt(110)

The decomposition reactions of formaldehyde on clean and oxygen dosed Pt(110) have been studied by LEED, XPS and TPRS. Formaldehyde is adsorbed in two states, a monolayer phase and a multilayer phase which were distinguishable by both TPRS and XPS. The saturated monolayer (corresponding to 8.06 × 10 14 molecules cm −2) desorbed at 134 K and the multilayer phase (which could not be saturated) desorbed at 112 K. The only other reaction products observed at higher temperatures were CO and H 2 produced in desorption limited processes and these reached a maximum upon saturation of the formaldehyde monolayer. The desorption spectrum of hydrogen was found to be perturbed by the presence of CO as reported by Weinberg and coworkers. It is proposed that local lifting of the clean surface (1 × 2) reconstruction is responsible for this behaviour. Analysis of the TPRS and XPS peak areas demonstrated that on the clean surface approximately 50% of the adsorbed monolayer dissociated with the remainder desorbing intact. Reaction of formaldehyde with preadsorbed oxygen resulted in the formation of H 2O (hydroxyl recombination) and CO 2 (decomposition of formate) desorbing at 200 and 262 K, respectively. The CO and H 2 desorption peaks were both smaller relative to formaldehyde decomposition on the clean surface and in particular, H 2 desorbed in a reaction limited process associated with decomposition of the formate species. No evidence was found for methane or hydrocarbon evolution in the present study under any circumstances. The results of this investigation are discussed in the light of our earlier work on the decomposition of methanol on the same platinum surface.

Determination of gross kinetic parameters for petroleum formation from Jurassic source rocks of different maturity levels by means of laboratory experiments

Solvent-extracted core samples of Lower Toarcian carbonate-rich shales (“Posidonia Shale”, Lias ϵ) of the Hils syncline area, Lower Saxony Basin, northern Germany, covering a wide maturity range (vitrinite reflectance, R r = 0.48, 0.88 and 1.45%) and a Kimmeridge mudstone ( R r = 0.45%) are pyrolyzed at three different heating rates (0.1, 0.7 and 5.0 K/min). By application of non-isothermal first-order reaction kinetics to the resulting hydrocarbon evolution curves activation energy distributions between 46 and 70 kcal/mol and pre-exponential Arrhenius factors are obtained by an iteration method. Hypothetical hydrocarbon generation curves are calculated for the Lias ϵ assuming three geological heating rates (0.5, 5 and 50 K/10 6a). Peak hydrocarbon generation temperatures range from 135 to 165°C.

Spatial variations of the 3 micron emission features within UV-excited nebulae: photochemical evolution of interstellar polycyclic aromatic hydrocarbons.

We have obtained 3 microns spectra at several positions in the Orion Bar region and in the "Red Rectangle," the nebula surrounding HD 44179. The recently discovered weak emission features at 3.40, 3.46, 3.51, and 3.57 microns (2940, 2890, 2850, and 2800 cm-1) are prominent in the Orion Bar region. The 3.40 microns and 3.51 microns features increases in intensity relative to the dominant 3.29 microns (3040 cm-1) feature when going from the ionized to the neutral zone across the Orion Bar. However, only a weak and rather broad 3.40 microns feature is present at the position of HD 44179. These spectra demonstrate that some of the 3 microns emission components vary independently of each other and in a systematic way within UV-excited nebulae. This spatial variation is discussed in terms of the UV excitation and photochemical evolution of polycyclic aromatic hydrocarbons and related molecular structures. The spatial behavior of the weak emission features can be understood qualitatively in terms of hot bands of the CH stretch and overtones and combination bands of other fundamental vibrations in simple PAHs. An explanation in terms of emission by molecular sidegroups attached to the PAHs is less straightforward, particularly in the case of the Red Rectangle and other evolved mass-losing objects. We estimate PAH sizes of 20-50 carbon atoms based on the susceptibility of PAHs to destruction by the far ultraviolet fields present in the Orion Bar and the Red Rectangle; the size range is similar to independent estimates made previously.

PYROLYSIS OF SUNNYSIDE (UTAH) TAR SAND: CHARACTERIZATION OF VOLATILE COMPOUND EVOLUTION

ABSTRACT Sunnyside (Utah) tar sand was subjected to programmed temperature pyrolysis and the volatile products were detected by tandem on-line mass spectrometry (MS/MS) in real time analyses. A heating rate of 4°C/min from room temperature to 900°C was employed. Evolution of hydrogen, light hydrocarbons, nitrogen-, sulfur-, and oxygen-containing compounds was monitored by MS or MS/MS detection. Evolution of volatile organic compounds occurred in two regimes: 1) low temperature (maximum evolution at 150 to 175°C), corresponding to entrained organics, and 2) high temperature (maximum evolution at 440 to 460°C), corresponding to cracking of large organic components. Alkanes and alkenes of two carbons and higher had temperatures of maximum evolution at approximately 440°C, and methane at approximately 474°C. Aromatic hydrocarbons had temperatures of maximum evolution slightly higher, at approximately 450° C. Some nitrogen-, sulfur-, and oxygen-'ccntaining compounds were also detected in the volatile products....

Comparative study of the isothermal pyrolysis kinetic behaviour of some oil shales and coals

Data are presented on the kinetics of hydrocarbon evolution from isothermal pyrolysis of four oil shale and two coal samples. Similarities and differences in the pyrolysis kinetics of the six samples are discussed. A fluidized-bed reactor coupled with a flame ionization detector as a monitor was employed. The rate of generation of the volatile hydrocarbons at each isothermal temperature can be described as a linear combination of three parallel independent first-order reactions. This model was found to be suitable for the six samples studied despite the large differences in the mineral matrix and the type of the organic matter. The activation energies calculated from the measured half-lifetimes depend on the temperature range; thus the activation energies measured inthe 400–450°C range were about 10 kcal/mole lower than those measured in the 450–500°C range. The kinetics of hydrocarbon evolution from samples previously exposed to 400°C were slower than the reaction kinetics of the original matter measured at a higher temperature range. This indicates that the kinetics slow down with maturation of the sample (or, as in this case, with a simulated maturation).

Vibrational studies of 1-propanethiol on Mo(110): Spectroscopic evidence for low temperature thiolate formation

The reactions of 1-propanethiol on Mo(110) have been studied using temperature programmed reaction spectroscopy and high resolution electron energy loss spectroscopy. Temperature programmed reaction spectroscopy demonstrates that 1-propanethiol decomposes on Mo(110), forming gaseous propane at 280 K, propene at 345 K, and dihydrogen at 360 and 545 K. Vibrational spectroscopy suggests that the key intermediate leading to propane and propene is a surface propyl thiolate, formed on adsorption at 120 K by scission of the SH bond. Competitive with hydrocarbon evolution is the formation of a surface hydrocarbon fragment of unknown stoichiometry, detected by the presence of a CH stretch, v( C H), at 2950 cm −1. The hydrocarbon fragment decomposes at ∼ 525 K to gaseous dihydrogen and surface carbon.

The significance of intermediate hydrocarbons during wall quench of propane flames

A one-dimensional model is used to study end-on wall quench using a detailed chemical kinetics mechanism for propane. Previous models using detailed chemical kinetics mechanisms for methane, methanol, and acetylene revealed that intermediate hydrocarbons exist at much lower levels than unreacted fuel molecules during quench, and thus led to the general conclusion that one-step global chemistry (which accounts only for the rate of disappearance of the fuel) is adequate for studying hydrocarbon evolution during wall quench. However, these fuels are extremely simple, low molecular weight molecules with very limited paths available for forming intermediate hydrocarbons. In the present study, wall quench is studied for propane-air mixtures at equivalence ratios of 0.9, 1.0, and 1.1; pressures of 1, 10, and 40 atmospheres; and wall temperatures of 400 and 500 K. It is shown that intermediate hydrocarbons exist at higher levels and at greater distances from the wall during quench than unreacted fuel. Furthermore, the intermediate hydrocarbons are oxidized less rapidly and persist at significant levels much longer after quench. The persistence of the intermediate hydrocarbons is aggravated by lower wall temperatures, lower pressures, and equivalence ratios both greater than and less than stoichiometric. At lower pressures, the rate of oxidation of the intermediate hydrocarbons is slowed to an even greater extent than is the fuel oxidation rate. The conclusion that intermediate hydrocarbons contribute significantly to wall quench hydrocarbon evolution indicates that one-step global chemistry is inadequate for studying turbulent wall quench, bulk quench, and crevice volume quench of higher hydrocarbon fuels and thus casts doubt on the use of the results of previous theoretical wall quench studies to obtain general conclusions regarding wall quench hydrocarbon evolution in practical engines using practical fuels.

Binding and Peroxidative Action of Oxyfluorfen in Sensitive and Tolerant Algal Species

Peroxidative activity of oxyfluorfen and binding of this nitrodiphenyl ether to cell fractions was investigated with the susceptible alga Scenedesmus acutus and the resistant alga Bumilleriopsis filiformis. Although a 10-fold higher concentration of oxyfluorfen was applied to Bumilleriopsis, the lag phase for initiation of peroxidative evolution of short-chain hydrocarbons from fatty acids was much longer than found with Scenedesmus. Oxyfluorfen was predominantly recovered after homogenization from the pellet which was separated into a lipid and a chloroform/methanol insoluble fraction. Parts of the oxyfluorfen which is present in the insoluble pellet fraction during the lag phase before the onset of peroxidation can be found in the lipid fraction when measurable peroxidative activities have started. This was observed with Scenedesmus as well as with Bumil-leriopsis. During peroxidation initiated by oxyfluorfen acyl lipids are degradated as monitored by the disappearance of the plastidic sulfolipid. Analysis of bound fatty acids showed that they are targets for peroxidative reactions in acyl lipids. Destruction of polyunsaturated fatty acids was higher than for saturated ones.

An Eight-Step Kinetics Mechanism for High Temperature Propane Flames

Abstract An accurate eight-step kinetics mechanism for the high temperature oxidation of propane has been developed. This model is based on previous experimental research and has been developed in ignition delay studies and investigations of freely propagating and quenching flames. Results from a detailed kinetics model and available experimental data were used for comparison and verification of the multi-step model. One-dimensional transient calculations were performed at pressures ranging from one to 40 atmospheres, unburned gas/wall temperatures from 400 to 500 K, and propane-air equivalence ratios from 0·7 to 1·3. Shortcomings in the earlier four-step and eight-step models are identified and strategies for improvement of the simplified model are discussed. Based on this work, the original eight-step model is modified to improve representation of the induction region, flame speed, postflame region, wall-quench behavior, and unburned hydrocarbon evolution. Correlations which extend the model to a wider ...

Binding and Peroxidative Action of Oxyfluorfen in Sensitive and Tolerant Algal Species

Peroxidative activity of oxyfluorfen and binding of this nitrodiphenyl ether to cell fractions was investigated with the susceptible alga Scenedesrnus aeutus and the resistant alga Bumilleriopsis filiformis. Although a 10-fold higher concentration of oxyfluorfen was applied to Bumilleriopsis, the lag phase for initiation of peroxidative evolution of short-chain hydrocarbons from fatty acids was much longer than found with Seenedesmus. Oxyfluorfen was predominantly recovered after homogenization from the pellet which was separated into a lipid and a chloroform/methanol insoluble fraction. Parts of the oxyfluorfen which is present in the insoluble pellet fraction during the lag phase before the onset of peroxidation can be found in the lipid fraction when measurable peroxidative activities have started. This was observed with Seenedesmus as well as with Bumilleriopsis. During peroxidation initiated by oxyfluorfen acyl lipids are degradated as monitored by the disappearance of the plastidic sulfolipid. Analysis of bound fatty acids showed that they are targets for peroxidative reactions in acyl lipids. Destruction of polyunsaturated fatty acids was higher than for saturated ones.

The pyrolysis kinetics of some Australian oil shales

The kinetics of hydrocarbon evolution from the pyrolysis of Rundle and Nagoorin shales can be described by two simultaneous first order rate laws whose relative contributions depend on the pyrolysis temperature. At low temperatures, a relatively rapid release of low molecular weight products occurs followed by a slower formation of higher molecular weight products. At high temperatures, secondary cracking reactions, resulting in the formation of low molecular weight aromatics, contribute to the total hydrocarbon release, and oil evaporation is kinetically important. The major constituents of the oil (alkanes, alkenes, aromatics) are formed at significantly different rates and according to different rate laws. The pyrolysis of Condor shale shows a marked particle size dependence, which cannot be described by any simple kinetic model, and is probably dominated by mass transfer effects.

The Influence of Coal Type on the Evolution of Polycyclic Aromatic Hydrocarbons During Coal Devolatilization

This study presents data showing the dependence of the types and quantities of PAH evolved during pyrolysis of coal on the aromatic nature of coal. A variety of coals ranging from low-rank lignite to anthracite have been pyrolyzed at well-controlled laminar conditions between temperatures of 900 and 1700°K. From GC-MS analysis it is concluded that the chemical type of PAH from different coals is similar. The concentration of PAH and soot formed, however, shows a distinct trend: high volatile bituminous > medium volatile > bituminous > subbituminous > lignite > anthracite.