CHROMATOGRAPHIC ISOLATION OF NITROGEN - CONTAINING COMPOUNDS IN LIQUID FUELS 2. THERMALLY TREATED SILICA GEL AS STATIONARY PHASE

Abstract

In the present work we describe a novel method for the isolation of the neutral N-containing fraction from crude oil by preparative liquid chromatography using thermally treated silica gel as stationary phase. The hydrocarbons are eluted in the first two fractions and the nitrogen compounds in the third fraction. The collected fractions are analyzed by HRGC-NPD. The method is shown to be very selective for the isolation of nitrogen compounds from the neutral fractions of crude oil.     

CHEMICAL ANALYSIS OF HIGH ASH BRAZILIAN COAL TAR. 1. PREPARATIVE LIQUID CHROMATOGRAPHIC FRACTIONATION.

ABSTRACT

A Brazilian high ash coal tar oil has been distilled into six distinct cuts (A to F) which are further fractionated by column liquid chromatography into eight discrete chemical classes (PLC1 to PLC 8). A proper sequence of eluents allows the separation of 5 classes containing hydrocarbons (saturated, olefinic, monoaromatic, diaromatic and polyaromatic), one of intermediate polarity (resins) and two polar fractions (asphaltenes and asphaltols). More than 50% of the oil is verified to distill above 300^°C. Infra-red and nuclear magnetic res-sonance spectroscopy confirms the sucess of the group-type fractionation. Very small amounts of hydrocarbons were found, the resins being the major fraction in all cuts studied.     

FITTED SHRINKAGE FORMULA OF SPIKED CRUDE OILS

ABSTRACT

Six Iraqi crude oils combined with six hydrocarbons or petroleum fractions have been subject to density and viscosity measurements, and precise data have been acquired on the volumetric behavior of these systems. A shrinkage formula with high accuracy and more accurate is developed when mixing hydrocarbons with crude oil.     

STUDY OF SATURATED COMPONENTS IN ASPHALT

ABSTRACT

The saturated fractions separated from blown and straight run asphalts of the same penetration grade have been investigated by using GC, MS and ¹³ The saturated components in asphalt represent complex mixture of polyalkyl structures in which straight chain paraffins prevail. The content of saturates in asphalt and their molecular composition were found to be affected by the chemical nature of crude oil as well as by the method of its processing into asphalt. Saturated fractions from blown asphalt are richer in long chain paraffins than those from straight run asphalts. The structural examination of saturated components separated from the products of asphalt pyrolysis has confirmed die presence of long straight-chain units in the asphalt-forming micelles. The structural differences between the saturated fractions obtained from asphalts of different origin (Uralian and Brent-blend) suggest, that the distribution of straigh-chain hydrocarbons in asphalts is dependent on the aliphatic network already existing in the raw material.     

CHEMICAL ANALYSIS OF HIGH ASH BRAZILIAN COAL TAR. 3. HYDROCARBON CHARACTERIZATION

In this paper we show the total analysis of the hydrocarbon fractions obtained from the chromatographic fractionation of a coal tar cut, previously described. All fractions were analyzed by Gas Chromatography coupled to Mass Spectrometry using a non-polar capillary column. A group-type distribution of aliphatic, olefins and monoaromatic hydrocarbons was found in the first three fractions obtained (I, II and III). In fractions IV and V polyaromatics with two or more condensed rings were founded. Many of these hydrocarbons are recognized to be carcinogenic and mutagenic, including pyrene, chrysene and others.     

Oxidative Degradation of Athabasca Bitumen,Fuel Oil,and Used Transformer Oil

Abstract

Oxidative cracking of bitumen, waxy fuel oil, and used transformer oils were carried out individually in an autoclave with 0.6 wt% of hydroquinone as a catalyst. The cracking process is conducted at 410°C in an atmosphere of oxygen gas of 0.15 MPa, for 30 min. The identification and quantitative determination of both the liquids and gases obtained during the cracking process are achieved using packed and capillary gas chromatography (GC) connected with suitable detectors. It was found that the degraded liquid products obtained have a higher percentage of lower hydrocarbons compared to the original feed stocks. Several analytical parameters including API gravity, calorific value, viscosity, density, pour point, etc., were used to evaluate the liquid product obtained. Also, the calorific values of the liberated gases were calculated and compared with that of natural gas. The cracked oil products were distilled and compared to their corresponding petroleum fractions. The cracked fractions have the same characteristics as their corresponding petroleum fractions with the exception of some properties that depend on the aromatic, naphthenic, and waxy nature of the virgin oil.     

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.     

CHROMATOGRAPHIC ISOLATION OF NITROGEN-CONTAINING COMPOUNDS IN LIQUID FUELS 1 Ti(IV) OXIDE GRAFTED ONTO SILICA AS STATIONARY PHASE

Abstract

The present work describes a novel method for the isolation of the neutral N-containing fraction from crude oil using column liquid chromatography on silica gel chemically modified with Ti(IV) oxide using a grafting method. The crude oil sample is introduced onto the column and eluted with a proper sequence of eluents. The first eluted fraction contains only hydrocarbons. The N-containing compounds are eluted in a isolated fraction. Both fractions are collected, concentrated and analyzed using HRGC with NPD detection. The method is shown to be very selective for the isolation of the neutral N-containing fractions from crude oil.     

DIBSOLUTION OF SOLID BOBCAN ASPHALTENES IN MIXED SOLVENTS.

ABSTRACT

Solid petroleum asphaltenes have been fractionated according to solubility in toluene/n-heptane mixtures of increasing toluene content. A large hysteresis was observed between this dissolution and the precipitation from the crude oil. In order to shed light on the solution mechanism, the fractions obtained have been analyzed using size exclusion chromatography (SEC-HPLC-UV-vis), VPO, elemental analysis, UV-vis adsorption spectroscopy and phenol interaction values and methylene content by FTir. Less polar non-associating low molecular weight species are dissolved and a specific extraction of porphyrins is observed. An increased association in the insolubles is indicated. More basic interaction sites are available on the asphaltenes in both fractions relative to the native asphaltene. From the SEC chromatograms it was seen that the soluble fractions did not associate as the insoluble fractions even when making up more than 60 % of the total asphaltenes.     

APPLICATION OF NATURAL AND SYNTHETIC FULLER'S EARTH TO THE FRACTIONATION OF BITUMEN

ABSTRACT

Synthetic (100% ) mentmorillonite and natural ( chlorite/ montmorillomite/palygorskite [33.3/36./30.5]) and Fullers earth have been used to fractionate bitumen. Insoite of the difference in the chemical composition and structure of the synthetic and natural Fuller's earth, their adsorption ability after activation are almost identical. Natural Fuller's earth was less selective in the soxhlet extraction compared to synthetic Fuller's earth. Pmr study of all fractions isolated indicate that HAB petrolenes have a high proportion of paraffinic and aromatic hydrocarbons and can be a good petrochemical feedstock. Fractions obtained from natural Fuller's earth are comparable to that isolated before using Attapulgus clay to fractionato Qaiyarah erude oil.     

Applications of Polycyclic Aromatic Hydrocarbons to Assess the Source and Thermal Maturity of the Crude Oils from the Lower Indus Basin,Pakistan

Abstract

A suite of six crude oils from Lower Indus Basin, Pakistan, were analyzed for geochemical characterization of source organic matter (OM) and thermal maturity. Distribution of polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, alkylphenanthrenes, alkyldibenzothiophenes, and aromatic biomarkers were reported from aromatic fractions of the crude oils. The aromatic hydrocarbons parameters revealed a higher thermal maturity of OM of source rock-generated Lower Indus Basin oils. Calculated vitrinite reflectance values from the methylphenanthrenes index 1 (MPI-1) and methyldibenzothiophene ratio (MDR) indicate that most of the oils reached a late oil generation window of thermal maturity. PAH distributions revealed the oils of two different origins are present in the Lower Indus Basin; two oil samples indicate aquatic source of OM and the aromatic biomarker distributions of retene, 1-MP, and 1,7-DMP indicate a significant contribution of land plant OM in the other four oils. This is the first study to report the distribution of aromatic hydrocarbons from Lower Indus Basin crude oils.     

CHROMATOGRAPHIC SEPARATION AND CHARACTERIZATION OF MONO-, DI- AND TRIAROMATIC HYDROCARBONS IN GAS OIL

ABSTRACT

A simple procedure is described for separation of aromatic hydrocarbons into mono-, di- and trinuclear types in Iraqi gas oil. This is accomplished by elution through an alumina adsorption column under standardized conditions. Characterization is performed by UV-absorption and ratio matching method. The method can be used also for investigating aromatic hydrocarbon structures of other petroleum fractions.     

Conversion of Mixed Lower Olefins and Paraffins on Galloaluminosilicate

At many oil refineries and gas processing plants, the C₂–C₅ fractions obtained as by–products do not have any qualified application. These hydrocarbons can be converted into valuable products on zeolite–based catalysts from the pentasil family. The characteristics of conversion of mixed C₂–C₄ olefins and paraffins into aliphatic and aromatic C₅₊ hydrocarbons in the presence of a galloaluminosilicate catalyst with the structure of pentasil were investigated. The temperature intervals of formation of isoparaffins from ethylene and propylene and aromatic hydrocarbons from mixed C₂–C₄ olefins and paraffins were found. Key words: C₂–C₄ olefins and paraffins, aliphatic and aromatic hydrocarbons, zeolites of the pentasil family, galloaluminosilicates.     

SIMULATED DISTILLATION BY TRERMO GRAVIMETRIC MEASUREMENTS APPLIED TO THERMAL CRACKING AND THERMAL HYDROCRACKING

ABSTRACT

A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C.

The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks

The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields

Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking

The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.     

STUDIES ON SLUDGE FROM WAXY CRUDE OIL STORAGE TANK. II. SOLVENT FRACTIONATION

Abstract

The sludge formed from crude oil (Bombay High crude oil) dump storage has been analysed by solvent extraction with a series of solvents of increasing polarity. The extract fractions so obtained have been analysed extensively. The nature of the sludge is compared with the similar sludges reported by other workers.     

Coking Mechanisms Within RFCC Disengagers

Abstract

In this article we review and analyze the causes of coking within Residua Fluidized Catalytic Cracking (RFCC) process disengagers. The existing literature points to the presence of fine catalyst particles and condensation of heavy fractions of RFCC products as the primary, physical causes of coking in these units. Chemical causes include condensation reactions of heavy aromatic hydrocarbons, resins, and asphaltenes as well as cyclization and polymerization of olefins and diolefins. Based on analysis of known coking mechanisms within RFCC disengagers, it is apparent that coking occurs by different mechanisms in the vapor and liquid phases of RFCC products. Therefore, the key to the inhibition of coke formation is to prevent the condensation of heavy fractions in the RFCC products and to decrease residence time of these products in the disengagers.     

THERMODYNAMIC FUNCTIONS OF THE SOLID-LIQUID TRANSITION OF HYDROCARBON MIXTURES

ABSTRACT

The dependences of the melting temperature and the enthalpy of fusion on the composition are the essential factors for modelling precipitation and solubility of solid hydrocarbons in crude oils and crude oil products. Long-chain iso-alkanes and cyclic alkanes must be considered besides of n-alkanes. Therefore a degree of isomerization and cyclization was defined using the refractive index and the carbon number. The melting temperatures and the enthalpies of fusion of different n-alkanes and fractions of crude oil were determined by differential scanning calorimetry. Both parameters can be correlated with the degree of isomerization and cyclization by a quadratic fuction.     

13C-N.M.R. STUDIES OF A FLASH PYROLYSIS TAR AND A SUPERCRITICAL GAS EXTRACT USING MODERN PULSE SEQUENCES

ABSTRACT

The oil and the asphaltene obtained from a flash pyrolysis tar of an Australian sub-bituminous coal and the oil and asphaltene from a supercritical gas extract of an Australian bituminous coal were studied by ¹³;c-n.m.r. apectroscopy using modern pulse sequences which distinguish between primary (CH₃), secondary (CH₂), tertiary )CH( and quaternary (C) carbons. The oil from the flash pyrolysis tar was further separated into three fractions by elution chromatography and these were also studied. All the samples studied contained considerable amounts of long unsubstituted aliphatic chains. In the flash pyrolysis tar, a sizeable proportion of the long chains had a CH = CH₂ end group pertaining to both 1-alkenea and those chains attached to aromatic rings (w-aryl-1-alkenes), but this was much less in the supercritical gas extract. From the quaternary and tertiary carbon subspectra, it appears that the division of the aromatic carbon signal at 129-130 ppm between aromatic CH and C carbons is not valid for polar fractions of coal liquids. Though these pulse sequences are very useful for obtaining information on well resolved signals, broad featureless signals often found in coal liquids pose considerable problems.     

Estimating Methyl/Methylene Groups in Asphaltene and Other Fractions of Asphalt

Abstract

Infrared is the most widely used analytical method for interpreting the structure of petroleum fractions. In this study, IR spectra of standard normal nonadecane were used to get ε for methyl and methylene groups. A linear relationship was obtained by plotting the peak intensities at 2,954, 2,926, 2,854, 1,466, and 1,376 cm^?1 against different amounts of N-nonadecane. The R ² obtained for most of the plots was in the range of 0.988–0.997. The Beer-Lambert's law was used for the first time to quantitatively estimate the weight percent of methylene and methyl groups present in the different fractions of asphalt.     

ANALYSIS OF SHHP ASPHALT NONPOLAR FRACTIONS BY SUPERCRITICAL FLUID CHROMATOGRAPHY

ABSTRACT

Three different fractions derived from each of eight SHRP asphalts were analysed by means of supercritical fluid chromatography. The three fractions were a low molecular weight neutral fraction obtained by ion exchange chromatography, a low molecular weight fraction obtained by size exclusion chromatography, end maltenes obtained by precipitation with hydrocarbon solvents. For a given asphalt, these fractions contain much of the same material and all comprise over one-half of the bulk of the asphalts. The ion exchange chromatography neutral fractions contain minimal amounts of polar materials. Based on the microstructural model of asphalt structure, any one of the three fractions might be considered to represent the solvent phase of an asphalt.

The supercritical fluid chromatograms of the asphalt fractions showed that they comprise materials of widely ranging carbon numbers, from 30 to over 110. Chromatograms of all three fractions of each asphalt are similar, particularly the low molecular weight size exclusion chromatography fractions and the maltenes. Chromatograms of fractions derived from different asphalts can differ greatly. The chromatograms of fractions of sol-type asphalts exhibit peaks corresponding to constituents that are more aromatic and of higher carbon number compared with chromatograms of fractions of gel-type asphalts. Thus supercritical fluid chromatography is a useful tool for the investigation of relatively nonpolar fractions derived from asphalts