New Statistical Concepts for Prediction Viscosity,Critical Temperature,and Critical Pressure of Homologous Hydrocarbon Series (C n H2n+2)

Abstract

A new model for prediction viscosity, critical temperature, and critical pressure for homologous hydrocarbon series C _n H_2n+2 as a function of carbon number only. The new model has a general formula: η or T _c or P = A ₁ C ^{A ₂} (2+2C) ^{A ₃} . This new model provides accurate and computationally reliable prediction for the corresponding properties (η, T _c , and P _c ) value.     

New Generalized One-Parameter Vapor Pressure Formula of Homologous Pure Hydrocarbon Series

Generalized formula has been developed to calculate vapor pressure of pure hydrocarbon series (C_nH_2n+2) from C₁₁H₂₄ to C₃₅H₇₂ based on one parameter “carbon number” only. As a result this technique is considered to be useful for prediction of vapor pressure of pure hydrocarbons, since it is possible to use this formula depending on simple parameter “carbon number”.     

AN EXPERIMENTAL STUDY OF THE EFFECT OF PARAFFINIC SOLVENTS ON THE ONSET AND BULK PRECIPITATION OF ASPHALTENES

ABSTRACT

Asphaltene onset concentration and bulk deposition were measured for a typical live reservoir oil titrated with n-C₆H₁₄, n-C₅H₁₂, n-C₄H₁₀, C₃H₈, C₂H₆, CH₄ and CO₂ at 100° C (212 ° F) and 29.9 MPa (4340 psia). The concentration of titrant at asphaltene onset was observed to decrease approximately in a linear fashion with decreasing molecular weight of the paraffinic solvent; CH₄ did not induce any asphaltene precipitation. Bulk deposition experiments were performed using a solvent: oil volume ratio of 10:1; the results indicated that the weight percent of asphaltenes precipitated increased exponentially with decreasing molecular weight of the paraffinic solvents. More importantly, the asphaltene molecular weight showed a maximum for n-C₄H₁₀ precipitated asphaltenes. Possible explanations for this unusual result are presented.     

QUANTITATIVE SEPARATION AND EVALUATION OF FISCHER-TROPSCH REACTION PRODUCTS HAVING LOW 14C-ISOTOPIC ACTIVITY

ABSTRACT

A method has been developed to effect the separation of Fischer-Tropsch products, predominately hydrocarbons, into, first, alkane and alkene fractions, and, secondly, each of these fractions into their normal and branched components. Conditions for methods using a “dry” silica column for the first separation and molecular sieves for the second separation have identified that permit collection of sufficiently large samples for subsequent separations. The first separation has been effected so the normal to branched chain ratio has not been altered. Liquid chromatographic conditions have been found whereby the n-alkane fraction can then be separated to provide a pure sample of each alkane in the C₈ - C₂₄ carbon number range. The alkane fractions have been collected so that the ¹⁴C activity can be determined for each alkane.     

Determination of acetylene solubility in dispersed water by computer simulation

The interaction of acetylene molecules with the (H₂O)₂₀ cluster was studied by molecular dynamics simulation. The behavior of the derivative of the chemical potential (?μ/?i)_V,T (i is the number of acetylene molecules) shows that the cluster stability is retained when no more than two C₂H₂ molecules add to the cluster. The system composed of (C₂H₂)_i(H₂O)₂₀ clusters has higher values of dielectric permittivity (both real and imaginary terms) than the (H₂O)_{20 + n} cluster system. The medium formed by water clusters with C₂H₂ molecules both absorbs and reflects IR radiation with a higher intensity as compared to a system of this type with pure water. The addition of C₂H₂ molecules to water clusters is also accompanied by an increase in the number of bands in an IR reflection spectrum. Adsorbed C₂H₂ molecules are aligned with the tangent to the water core of the cluster, thus impeding their penetration into the aggregate and, hence, decreasing the solubility of acetylene.     

Possible origin of high molecular weight n-alkan-2-ones in jurassic bitumens from the Sichuan Basin in Southwest China

Lipid extracts from two Sichuan (China) bitumens have been systematically analyzed using gas chromatography—mass spectrometry (GC-MS). These extracts contain C₂₅-C₃₅ n-alkan-2-ones with predominantly odd-carbon number homologs in the Yangba (YB) extracts and with exclusively odd-carbon number homologs in the Penglai (PL) extracts. We suggest that the n-alkan-2-ones with odd numbers of carbon atoms originated due to degradation (cleavage) of fatty acid salts containing one less carbon atom to form methyl and carbonyl radicals, followed by reaction between the latter. The distribution of n-alkan-2-ones with respect to number of carbon atoms can be used to identify the organic matter in sedimentary rocks from which the fatty acid salts were formed.     

Petroleum naphthenomono-and naphthenobiarenes

The hydrocarbon-group composition and distribution of naphthenoaromatic hydrocarbons of West Siberian oils were studied by the technique of mass spectrometry. Naphthenoaromatic hydrocarbons of the general formula C_nH_2n?z , where z is 8, 10, 12, 14, 16, or 18, containing from one to six saturated cycles are present in oils in significant concentrations. Naphthenomonoarenes with one saturated cycle dominate in all oils. An increase in the amount of compounds containing 3–6 saturated cycles in their molecule with the occurrence depth was noted. Naphthenobiarenes of the general formula C_nH_2n?z , where z is 14, 16, 18, 20, 22, or 24 containing from one to six saturated cycles are present in oils in concentrations from 20.0 to 54.0 wt % of the biaromatic fraction. Most oils are characterized by the prevalence of structures with one and two saturated cycles in their molecule. The dependence of the number of cycles in naphthenobiarenes on the nature of original organic matter (OM) was not traced. The lack of correlation between the number of cycles and the OM type is presumably due to the fact that, for the most part, fused polycyclic naphthenobiarenes reflect the degree of catagenetic alteration of organic matter.     

THERMAL STABILITY ANALYSIS OF THE LIQUID PHASE METHANOL SYNTHESIS REACTOR

ABSTRACT

The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H₂-rich and CO-rich syngas respectively, were used to experimentally verify the “slope” and “dynamic” critria in a three-phase fixed bed recycle reactor. The liquid medium, witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapor phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics.     

Optimization of Oxidative Desulfurization of Dibenzothiophene Using a Coordinated Ionic Liquid as Catalytic Solvent

Abstract

Oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane with hydrogen peroxide/acetic acid using a quaternary ammonium coordinated ionic liquid (IL) (C₄H₉)₄NBr · 2C₆H₁₁NO as catalytic solvent has been studied. The ODS mechanism by coordinated ionic liquid [(C₄H₉)₄NBr · 2C₆H₁₁NO] was also carried out. The sulfur-containing compounds in model oil were extracted into ionic liquid phase and oxidized to their corresponding sulfones by H₂O₂. The effect factors for desulfurization of model oil were investigated in detail by means of monofactorial and orthogonal experiments (L₁₆(4)⁴). The results showed that the desulfurization efficiency of model oil could reach 98.6% under the optimal conditions of oxidation time, oxidation temperature, molar ratio of H₂O₂/sulfur (O/S), and volume ratio of model oil to coordinated ionic liquid were 30 min, 50°C, 16, and 1, respectively. The influences to the desulfurization efficiency of DBT decreased in the following order: volume ratio of model oil to coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO (V_{model oil}/V_IL) > molar ratio of O/S > oxidation temperature > oxidation time, according to extreme analysis of the orthogonal test. The coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO can be recycled 5 times without a significant decrease in desulfurization.     

Conversions of mixtures of propane and benzene on Pt,Re/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> + H-zeolite systems

The conversion of C₆H₆: C₃H₈C mixtures on mixed catalysts composed of the metal catalysts Pt,ReOx/Al₂O₃ and zeolites Y, M, and ZSM-5 in the H form was studied. The products of benzene dehydroalkylation by propane and propane dehydrogenation products are formed at 180–350°C. It has been shown that propane is activated on the metal catalysts and C₆H₆ interacts with the zeolites yielding the C₆H₇ ⁺ intermediate, which acts as an agent of proton transfer from a zeolite to a metal catalyst, and another intermediate C₉H₁₃⁺ (I). Cumene, alkylbenzenes, and propene are formed as a result of the conversion of I. A comparison of the results of the conversion of these mixtures on the composite catalysts with different zeolites shows that the formation of cumene and propene is thermally controlled and the formation of the other products is kinetically controlled. It has been concluded that the coupling of the redox properties of the metal catalysts with the acid-base properties of the zeolite catalysts facilitates the low-temperature transformations of the mixtures.     

Distribution of high-molecular-weight <Emphasis Type="Italic">n</Emphasis>-alkanes in paraffinic crude oils and asphaltene-resin-paraffin deposits

Paraffinic and high-paraffin oils and asphaltene-resin-paraffin (ARP) deposits of Samara oblast have been investigated by differential scanning calorimetry (DSC) and GLC techniques. High-paraffin oils have been found to contain n-alkanes with the number of carbon atoms of C₁₅-C₆₀ and higher forming a crystalline phase with the mp ∼30–40°C. The ARP deposits from high-paraffin oils almost do not contain highmolecular-weight n-alkanes with the number of carbon atoms >55. This is due to the peculiarities of the crystallization and cocrystallization processes of high polydispersity n-alkanes in crude oils.     

A New Correlation for Estimating Saturated Vapor Pressure and Acentric Factor of Pure Hydrocarbons

Abstract

In this work, a generalized equation based on the Wagner equation was used for estimating saturated vapor pressure of pure compounds. This model is presented for correlating the saturated vapor pressure of 40 pure compounds and 718 experimental data points. The new model was used for estimating the acentric factor of pure substances based on this saturated vapor pressure equation. Acentric factors of 300 compounds were calculated according to this equation and compared with the related reference values. The average absolute deviations (AAD%) show that the equation has good accuracy for estimating the saturated vapor pressure and acentric factor of pure compounds.     

Synthesis of adamantane and diamantane hydrocarbons by high-temperature cracking of higher n-alkanes

Adamantanes and diamantanes, whose abiogenic synthesis from carbon and hydrogen is feasible, were synthesized via the high-temperature cracking of individual n-alkanes in order to reveal the possible ways of the genesis of hydrocarbons with a diamond-like structure. As a result of the high-temperature cracking of n-alkanes, all theoretically possible isomers of C₁₀–C₁₃ adamantanes and C₁₄–C₁₆ diamantanes are formed, as well as n-alkanes up to C₃₅H₇₂ and coke.     

Modeling of formation of petroleum biomarker hydrocarbons by thermolysis and thermocatalysis of bacterium biomass

Thermolysis and thermocatalysis of the insoluble part of chemoorganoheterotrophic aerobic bacteria Arthrobacter sp. RV and Pseudomonas aeruginosa RM have been performed. The thermolyzates and thermocatalyzates of these bacteria contain the hydrocarbon biomarkers n-alkanes, isoprenanes, steranes, and terpanes. Of n-alkanes, the C₉-C₃₅ hydrocarbons with unimodal distribution formed in the products of or C₉-C₃₉ n-alkanes with bimodal distribution are produced by thermolysis or thermocatalysis, respectively. n-Alkanes with odd number of carbon atoms in the molecule prevail over the even counterparts (n-C₉, n-C₁₁, n-C₁₅, and n-C₁₇) in the thermolysis products of both strains, whereas n-alkanes with even number of carbon atoms (n-C₁₆, n-C₁₈, and n-C₂₀) dominate in the thermocatalyzates. Isoprenanes of the C₁₃-C₂₀ composition are generated. It is noteworthy that regular C₁₇ isoprenane has been found for the first time among isoprenanes. The cyclic biomarker hydrocarbon steranes and terpanes are simultaneously generated, with the distribution of C₂₇-C₂₉ regular steranes resembles that in marine oils generated in argillaceous strata. At the same time, the adiantane to hopane ratio (H₂₉/H₃₀) is characteristic of the organic matter generated in carbonate strata.     

Kinetic Model of Heavy Paraffins Dehydrogenation

Kinetics of reaction and catalyst deactivation were determined based on the dehydrogenation of C₁₀ ? C₁₃ heavy paraffins to the corresponding mono-olefins, and Powell method was used to optimize the parameters. Activation energy and pre-exponential factor presented linear relationship with carbon number. The results showed that dehydrogenation became easier with the increase of carbon number of heavy paraffin and the deactivation of catalyst became slower with the increase of LHSV and pressure. The validation of kinetic model showed it was in good accordance with experimental data.     

Dissociation behavior of （CH4 ＋ C2H4） hydrate in the presence of sodium dodecyl sulfate

Separation of a mixture of CH4+C2H4 gas by forming hydrate in ethylene production has become of interest,and the dissociation behavior of(CH4+C2H4) hydrate is of great importance for this process. The hydrate formation rate could be increased by adding a small amount of sodium dodecyl sulfate(SDS) into water. In this work,the kinetic data of CH4(18.5 mol%) +C2H4(81.5 mol%) hydrate decomposition in the presence of 1000 mg·L-1 SDS at different temperatures and pressures were measured with the depressurizing m...     

Influence of H2S Content on CO2 Corrosion Behaviors of N80 Tubing Steel

Abstract

The corrosion behaviors of N80 steel in pure CO₂ and at different partial pressure ratios of CO₂/H₂S were tested by high-temperature and high-pressure autoclave. At 90°C, with the additional H₂S to pure CO₂, the surface corrosion condition improved greatly and the corrosion rates were lower than in pure CO₂ condition. With the increase of partial pressure ratio, the corrosion rate reached a peak value at pCO₂/pH₂S = 100 and then declined. The corrosion products of the samples in different conditions were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) methods. The inner film is finer and denser than the outer scale.     

Investigation of Asphaltene Precipitation Process for Kuwaiti Reservoir

Abstract

As part of an Enhanced Oil Recovery (EOR) research program, Asphalting precipitation processes were investigated for a Kuwaiti dead oil sample using different hydrocarbons and carbon dioxide as precipitants at the ambient and high pressure of 3000 psig conditions. The hydrocarbons used as precipitants were ethane (C2), propane (C3), butane (C4), normal pentane (n-C5), normal hexane (n-C6), and normal heptane (n-C7). The equipment used for this investigation was a mercury-free, variable volume, fully visual JEFRI-DBR PVT system with laser light scattering. The minimum critical value of precipitants concentration for the oil sample has been identified at the ambient and high-pressure conditions for each precipitant. Our investigation has revealed that for this oil sample the most powerful asphaltene precipitant were CO₂ followed by C2, C3, C4, n-C5, n-C6, and n-C7. Moreover, the effect of pressure and temperature on the asphaltene precipitation has been investigated experimentally for CO₂, n-C5, n-C6, and n-C7. The precipitation and redissolution of asphaltene upon the addition and removal of CO₂ and light alkanes (C2–C4), at 3000 psig and ambient temperatures, have shown evidence of reversibility of asphaltene precipitation. A comprehensive fluid characterization analysis for the oil sample has been performed including, physical properties of crude oil, compositional, molecular weight (Mw), and SARA analyses. Advanced analytical techniques such as 1H and 13C NMR and IR spectrometers have been utilized to investigate the molecular structure of the asphaltene for this sample. It was concluded that the asphaltene molecules for this oil contain 120 total aromatic carbons with 42 aromatic rings, 114 naphthenic rings, and 5–7 sets of condensed aromatic rings.     

天然气组分的水合常数、水合热及理论溶解度

天然气在水中的溶解度是天然气地球化学定量研究中的基础参数。欲应用理论公式计算天然气组分在水中的溶解度,关键在于建立天然气组分的水合平衡常数与温度的关系。本文利用天然气组分的溶解度数据,标定了甲烷、乙烷、丙烷、N₂、CO₂和H₂S的水合常数与温度的关系,从而建立了上述组分的理论溶解度公式。经验证,至少在下述分压范围内,上述气体的溶解度计算值与实测值基本吻合:甲烷≤60MPa;乙烷≤5MPa;丙烷≤3MPa;N₂≤50MPa;CO₂≤5MPa;H₂S≤5MPa.天然气的水合热是研究气水合物形成的重要参数。研究表明,天然气组分的水合反应符合一般的化学反应规律。根据计算,上述气体的水合热分别为:甲烷,-17.741;乙烷,-10.471;丙烷,-9.441;CO₂,-17.520;N₂,-15.418;H₂S,-11.845(负号表示水合反应为放热反应,水合热的单位:kJ/mol).从理论上证明了当压力趋向无穷大时,气体的溶解度趋向一极限值。