CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES IN FORTIES AND KUWAIT PETROLEUM CRUDES

ABSTRACT

Alkane hydrocarbon fractions from Forties (North Sea) and Kuwait petroleum crudes, separated by distillation, solvent extraction and silica-gel column chromatography and sub-fractionated by molecular-sieve adsorption, have been examined by gas chromatography (GC) ¹H and ¹³C ( NMR spectroscopy, GC-mass spectrometry (MS) and field desorption (FD)MS. GC indicates that Forties contains rather more acyclic isoprenoids and cyclic alkanes than Kuwait; FDMS of Kuwait shows molecular-weight ranges for mono-, di-, tri-, tetra- and pentacyclic alkanes. ¹³C NMR spectra provide evidence of higher aromatic carbon, C_A, in Forties than Kuwait and longer T₁ relaxation times.     

THERMAL DECOMPOSITION OF SAUDI CRUDE OIL ASPHALTENES

Abstract

Asphaltenes precipitated by the use of pentane, heptane and decane solvents from Saudi Arabian Light (AL) and Saudi Arabian Heavy (AH) crude oils 370^°C + residua have been investigated by thermal gravimetric analysis and pyrolysis - gas chromatographic analysis at 350^°C and 520^°C. Gas chromatographic analysis of the gases evolved during pyrolysis has shown that CO, CO₂ and CH₄ constitute the major portion of the gases evolved at 350^°C from pentane and heptane asphaltenes of AH residue and from pentane asphaltenes of AL residue. Whereas gases evolved from decane asphaltenes are dominated by CO₂ and C₂-C₄ hydrocarbon gases. At 520^°C, hydrogen and methane represent 56-80 vol %of the gases evolved from all the four asphaltenes. The amounts of C₁-C₄ hydrocarbon gases increased with an increase in the carbon number of the precipitating solvent at 350^°C and decreased at 520^°C. The presence of up to C₃₆ normal alkane hydrocarbon has been indicated in the maltenes produced from these asphaltenes. The loss of nitrogen from AH asphaltenes during pyrolysis remained low (1-6 wt %), whereas the losses of oxygen and sulphur ranged from 58 to 74 wt % and 10 to 29 wt %, respectively.     

13C SOLID STATE NMR OF ALBERTA SUBBITUMINOUS MACERALS

ABSTRACT

The relaxation time behavior for three macerals (vitrinite, fusinite, and resinite) of a subbituminous coal has been extensively characterized by ¹³C solid state nor. Parameters studied included free radical concentrations. ¹³C spin-lattice relaxation, T₁ ^C, cross polar1zation times, T_CH, proton rotating frame spin-lattice relaxation. T_1P ^H. dipolar dephasing times. T₂ ¹, aromaticity, f_a, and the effects of spinning sideband suppression on f_a,. Large chemical shift variations among these samples were observed and assigned to various possible structural entities. Correlations between proximate and ultimate analyses and the nmr results, as well as comparisons with previously reported relaxation times are made.     

STUDY OF STRUCTURAL FEATURE OF PEAT,LIGNITE AND HUMIC ACID BY SOLID STATEl3C NMR SPECTROSCOPY

Abstract

Four low rank coals (peat and lignite) and their derived humic acids have been investigated by the^l3C CP/MAS/TOSS NMR technique. The NMR analysis indicates that the peat contains a significant amount of unaltered plant components including cellulose, hemicellulose, lignin, waxes, and resins.

Variable contact time and dipolar dephasing experiments were performed on each sample. The data from above experiments, together with normal CP/MAS integration over selected chemical shift range, were used to derive 12 parameters of carbon skeletal structure including the aromaticity.From the ratio of aromatic bridgehead carbons, f_a ^cp, to the aromatic peripheral carbons, f^cpxBp as measured by NMR, the aromatic cluster size may be estimated for each coal.     

COMPOSITIONAL DIFFERENCES BETWEEN SUPERCRITICAL FLUID EXTRACT AND SHORT-PATH DISTILLATES OF PETROLEUM SHORT RESIDUE

Abstract

Short-path distillation (SPD) and supercritical fluid extraction (SFE) procedures were employed to obtain portions of a short residue (500^°C+). The physicochemical and compositional data of SF extract and SP distillates at four wall temperatures were obtained employing various analytical techniques such as vapour pressure osmometry, simulated distillation, infrared and mass spectrometry. The comparison of these data reveals that although the yield of SF extract is small under the present experimental conditions, it contains relatively higher concentrations of paraffins and alkylbenzenes as compared to SP distillates. The hydro carbon type distribution of distillates was found to be the same, independent of the wall temperature used. The comparison of overall composition of SF extract and SP distillates depicts that former is more suitable to be used as lube stocks.     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

ABSTRACT

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

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.     

CHARACTERIZATION OF KUWAITI CRUDE TBF-FRACTIONS WITH EMPHASIS ON KINEMATIC VISCOSITY - TEMPERATURE BEHAVIOR

ABSTRACT

Characterization of Kuwaiti crude oil, has been carried out in terms o API gravity, debutanized gravity, total sulfur content, Reid Vapor pressure ash content, heating value, salt content, viscosity SUS, vanadium content a: V2 O5, pour point and analysis of various metals. The true boiling poinl (TBP) fractions of this crude (IBP - 95^° C, 95 - 205^°C, 205 - 260^° C, 260 - 345^° C and 455^° C⁺;) were also characterized in terms of API gravity, total sulfui content, H₂S content, mercaptans content, molecular weight and elementa analyses for total carbon, hydrogen and nitrogen. The kinematic viscosity temperature data have been obtained for 95^°C⁺; TBP fractions for a wide range of temperatures.     

KINETICS OF CORN COB CHAR GASIFICATION IN CARBON DIOXIDE

ABSTRACT

The Reactivity of corn cob char in CO₂ has been studied on a thermogravimetric balance to develop a rate equation for the design of biomass gasifiers operating on corn cob char. Experiments in the range of 650-1000^°C were conducted with cylindrical shaped pellets of 1 cm diameter having L/D=l. The average porosity of the pellets was 0.5. It was observed that the rate of the CO₂/char reaction decreased with increase in temperature from 650-750^°C and then increased with temperature upto 1000^°C.

The data obtained at temperatures 750^°C and above has been used to determine a rate equation for char gasification. It has been found that the reaction proceeds according to the Sharp Interface Model (SIM) with a first order chemical reaction as the rate controlling step. The activation energy is found to be 40 Kcal/mole with frequency factor being 1.2 × 10⁷ mm/sec. Analysis of the data obtained for the decreasing reaction rate regime (650-750^°C) indicates that the change in the ash structure result in this kind of behavior.     

CHARACTERIZATION OF SELENIUM CATALYST FOR COAL LIQUEFACTION IN TERMS OF HYDROGENATION AND CRACKING ABILITY

ABSTRACT

The activities of selenium and zinc chloride catalysts upon transferable hydrogen in coal have been investigated by ^IH-NMR. Se is more active than ZnCl₂ for hydrogen transfer in the coal/anthracene system. The change of radical concentration was monitored by high temperature ESR. It was confirmed that radical concentration in the coal/Se system is greater than that in the coal/ZnCl₂ system at the early stage of pyrolysis. It was concluded that Se has a higher cracking activity as well as hydrogen transfer ability and there is the potential for the use of Se as a catalyst for coal liquefaction.     

PYROLYSIS STUDIES OF ORGANIC OXYGENATES VI. THERMAL CHEMISTRY OF LONG CHAIN ALIPHATIC ACIDS

ABSTRACT

The thermal chemistry of two long-chain fatty acids, decanoic acid and tetradecanoic acid (myr1st1c add), has been determined at temperatures of 400-450^°C under Inert {helium and nitrogen) and reactive (hydrogen) atmospheres. In general the thermal chemistry pathways are similar to those found with aromatic acids. Secondary cracking type reactions were found to be much more Important for the fatty acids, leading to a very complex product mix.

As expected, decarboxylation and subsequent radical reactions are Important whether the pyrolysis is carried out In the presence of an Inert gas such as helium or whether a hydropyrolysis occurs. Consistent with what was previously demonstrated with an aromatic acid⁽⁷⁾ and an aryl alkyl ether⁽⁵⁾, hydropyrolysis suppresses CO_x formation and tends to generate more aldehydes and alcohols than are produced under conventional pyrolysis conditions.

For fatty acids under Inert atmosphere pyrolysis conditions, the major initial products are the alkanes and alkenes derived from loss of CO₂, and CO₂ Itself. When hydrogen is present In the vapor phase, additional major products are formed. These Include the alkane, alkene and aldehyde derived from reduction of the fatty add. In all cases there is a substantial yield of the ketone     

COMPARISON BETWEEN THE PERFORMANCE OF CONVENTIONAL AND HIGH-METAL Co-Mo AND Ni-Mo CATALYSTS IN DEEP DESULFURIZATION OF KUWAIT ATMOSPHERIC GAS OIL

ABSTRACT

Due to environmental constraints, sulfur content of diesel fuel has been restricted to very low levels (500 ppm maximum) in many countries. As a result, a greater emphasis has been placed in recent years on the development of catalysts and processes for deep desulfurization of diesel blending streams to produce low sulfur diesel fuel. In the present work we have compared the performance of a conventional Co-Mo catalyst with that of high metal loading Co-Mo and Ni-Mo catalysts in deep desulfurization of Kuwait atmospheric gas oil. The tests were carried out in a fixed bed reactor unit using 75 ml of catalyst under the conditions: P=32 bar; LHSV = 4h^?1; H₂/oil ratio = 100 ml/ml; temperature range = 330 ? 390°C. HDS activity of the high molybdenum Co-Mo catalyst was superior to that of the conventional Co-Mo hydrotreating catalyst. High metal loading Co-Mo/Al₂O₃ catalyst also showed a substantially higher HDS activity than the Ni-Mo/Al₂O₃ catalyst containing a similar high metal loading. The unreacted sulfur compounds remaining in the product after high severity hydrotreating were identified as dibenzothiophenes with alkyl substituents next to the sulfur atom. The desulfiirization of such low reactive alkyl dibenzothiophenes was found to occur at a substantially lower temperature over the high metal loading Co-Mo catalyst compared with the conventional Co-Mo catalyst. The results have been explained on the basis of the stacking and dispersion of MoS₂ slabs as well as in terms of the nature of the sulfur vacancies in the MoS₂ layers in these catalyst systems.     

COPROCESSING OF COAL WITH HEAVY PETROLEUM CRUDES AND RESIDUA

ABSTRACT

This work investigates the coprocessing of coal in six different heavy petroleum crudes and residua. Coprocessing reactions of coal and the petroleum solvents are performed under three sets of constant reaction conditions, yielding informative comparative data for processing applications. Definitive comparisons of coal reactivity and solvolysis in the petroleum solvents have been obtained using solvent fractionation which provides a measure of the degree of upgrading achieved by the liquefied coal. Regressive reactions and low coal conversions are observed in coprocessing reactions in N₂ at 400^°C. Higher conversions and a reduction in regressive reactions are observed in H₂ at 400^°C. Catalytic hydrotreatment and higher temperature, 425^°C, result in increased coal conversion and a net production of pentane soluble materials. The amount of product fractions obtained from the upgrading of the coal alone is calculated. The effect of reaction temperature using different solvents and reaction conditions on the product slate is also examined.     

DIMETHYL SULPHOXIDE-A SOLVENT FOR THE STUDY OF COALS

ABSTRACT

Dimethyl sulphoxide (DMSO) has been found to be a very good solvent for the study of Tow rank coals. Chemical studies of a Texas lignite, its DMSO soluble fraction obtained under ambient conditions, the DMSO insoluble residue and its humic acids have been carried out. Physico-chemical techniques such as Fourier transform infrared spectrometry (FTIR), and ¹³C cross-polarization/magic angle spin (¹³C CP/MAS) NMR spectrometry and chemical methods such as pertri fluoroacetic acid oxidation and the determination of acidic group concentrations have shown that the DMSO-soluble portion possesses a chemical structure which is similar to both that of the neat lignite and of the DMSO-insoluble residue. The humic acids are highly aromatic and acidic in nature. Preliminary data obtained through the use of ²⁵²Cf plasma desorption mass spectrometry (²⁵²Cf PDMS) suggests the existence of a common species in both the DMSO extract and the humic acids.     

MOSSBAUER STUDY OF Fe-Cu-K CATALYST FOR FISCHER-TROPSCH SYNTHESIS

ABSTRACT

Mosshauer spectroscopy (MES) has been used to study the characteristics of iron catalysLs preireated in different ways for Fischer-Tropsch (F-T) synthesis. The Mosshauer spectrum results showed that the fine particle of α-Fe₂o₃is the main phase of oxide catalyst. Catalysts preireated in H₂:CO ratio of 2.1 syngas at 250°C and under 0.5 MPa with the gas hourly space velocity of 1500 h^?for 32 h in a fixed-bed reactor resulted in the reduction of 91% of iron to Fe₃o₄, FeO and X-FC5C2- The κ-Fe₅s₂content of reacted catalyst increased greatly as compared with reduced catalyst, while FeO and Fe₃o₄contents decreased. The Fe₃O₄ content of catalyst poisoned by oxygen increased as compared with reduced catalyst. FeS₂ is the main phase of catalyst poisoned at high COS concentration, while FeS is the main phase of catalyst poisoned by COS al low concentration. The Fe₃o₄content decreased with the increase of sulfur fed to catalyst. The deactivation rate is related to the composition of the catalyst treated in concentrations.     

SOME REMARKS ON SURFACE FREE ENERGY OF POLISH COALS

ABSTRACT

On the basis of the studies concerning the determination of the surface free energy of Polish coals published earlier analyses of the equilibrium state of three-phase system were carried out. The three-phase systems were:

1) coal - liquid drop - air, 2) coal - water drop -air, 3) coal - water drop - hydrocarbon, 4) coal -hydrocarbon drop - water and 5) coal - air bubble -water.

Analysing the measured values of the contact angles in the systems studied the occurrence of a liquid film on the coal surface was taken into account. The surface free energy. of Polish coals results from both dispersion (T_s ^d) and nondispersion (T_s ⁿ) intermolecular interaction. A distinct relationship was found between the dispersion components of the surface free energy and coal ranks.     

SOAKER VISBREAK1NG OF SOME IRAQI RESIDUES

ABSTRACT

An attempt has been made to increase the fuel oil yield of two Iraqi residues using a soaker visbreaking process. This was carried out in a continuous laboratory scale unit at a range of mild conditions, namely, A20–A8O^°C and A3-109 sec. in the coil and 151–379 sec. in the soaker.

Physical properties of the products have been characterized and reported. The fuel oils obtained under the studied conditions remained stable compared with the original feedstocks. Furthermore, data on yield and characteristics of the different distillates from the visbroken products have been obtained. There was an increase in the distillates up to 350^°C (11%) for type A residue and (15%) for type B residue.     

THE STUDY OF PRODUCING HEAVY TRAFFIC ASPHALT BY USING THE HIGH VISCOUS CRUDE FROM NO.l SHUGUANG ZONE OF LIAOHE OIL FIELD

ABSTRACT

The characteristics of the high viscous crude from No. 1 Shuguang Zone of Liaohe Oil Field are similar to those of residue distillates of general crude such as high density(ρ ₂₀=0·9977 g.cm^-3),high viscidity υ ₁₀₀= 1223·9 mm².s-¹) and high carbon/hydrogen ratio. This oil contains less wax, but rich in resin and asphalt, which belongs to low sulfur naphthene-base crude oil and can be used as feedstock to produce high paving asphalt. But now it is used as fuel after emulsificating. In order to make full use of this oil and resolve the problem of paving asphalt demand-supply, various paving asphalts conforming to GB50092-96 standard were produced by blending vacuum residue of the high viscous crude from No.l Shuguang Zone of Liaohe Oil Field and waste oil which is rich in aromatics and poor in wax. The laboratory test results show that modified paving asphalts have good low-temperature properties and antiaging feature.     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

Abstract

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

THEORETICAL BASIS OF THE STRUCTURE OF BITUMENS AND OTHER ORGANIC BINDERS

Abstract

For the development of a general theory, organic binders (OB) are considered as two-phase disperse systems. The particle of the dispersed phase (Ph) is a nucleus (asphaltene, polymer, other filler) which immobilizes a part of the dispersing medium (M). Ph is a whole in heat motion and deformation.

The type of the disperse structure (DS) in OB and the properties of OB depend on the Ph volume (C_v ) equal to the product of the weight content of Ph, voluminosity coefficient λ (a relationship of volumes of Ph and their nuclei), the relationship of Ph densities and their nuclei.

C_v is a criterion of the general classification of OB on types of DS. At C_v = 0.487 and C_v = 0.613 we supposed and observed structural transitions. This is the basis of the method of designing OB with the required DS.

In theory the C_v -reduced highest Newtonian viscosity curve has been desdribed, the rheological method for determining basic parameters of DS of binders has been developed. Parameters of DS of 18 model bitumens containing various asphaltenes have been calculated. An adhesive ability of OB is conditioned by Van der Waals forces between particles of the dispersed phase and determined by the interaction constant we proposed.