ABSTRACT We studied the production of ethylene (C2") and propylene (C3") by the decomposition of pure ethane, propane, and n-butane, mixed with steam, in a microwave-irradiated fixed bed reactor packed with silicon carbide. We found that ethylene production was maximized using ethane as the feed, with per pass yields as high as 63% at an ethane conversion level of 74%. With propane and n-butane feeds, more ethylene than propylene was produced, but the propylene amounts were significant. Combined per pass yields of C2" and C3" were 56% at a butane conversion of 99%, and 50% at a propane conversion of 93%. This microwave process appears to be a viable way of producing ethylene and propylene.
The phase behaviour of heavy oil mixtures was studied using an X-ray imaging system. Batch phase experiments were performed at temperatures and pressures up to 725 K and 7 MPa. Complex phase behaviour such as liquid-liquid-vapour and solid-liquid-liquid-vapour were observed and preliminary experimental phase diagrams were constructed. This observed complex phase behaviour is consistent with thermodynamic theory and such phase behaviour can be modelled using the Peng-Robinson equation of state and the tangent plane criterion. These latter points are illustrated through the phase diagram for a model reservoir fluid (ethane + propane + n-butane + phenanthrene) which exhibits solid-liquid-liquid-vapour phase behaviour. Example predicted and experimental phase diagrams are presented for this model system.
ABSTRACT The liquefaction of sugar cane bagasse in monoethanolamine (MEA) in the presence of catalysts (zeolite A, non-zeolitic aluminosilicate and zinc chloride) as well as in the absence of catalysts is described in this paper. The influence of the catalysts on the yield of the generated products is verified through a fractionation method based on relative solubility parameters. The influence of the catalysts on the conversion yield was also verified. The catalysts that yields the greater quantity of oils is the non-zeolitic aluminosilicate. However, in the overall conversion process of sugar cane bagasse, the most efficient catalyst was found to be zeolite A.
ABSTRACT The mechanism of formation of carbonaceous deposits from hydrocracked Athabaca bitumen is shown to result in both isotropic and anisotropic solids. The formation of mesophase spheres present as a separate liquid phase has been observed in the laboratory High severity results in the formation of an increased amount of anisotropic solid which is observed in both laboratory and commercial samples. The formation of these deposits in the downstream separators of a commercial plant has occurred and is a hindrance to reliable operation. A strategy to reduce the formation of these deposits in a commercial plant was evaluated in a series of laboratory experiments. The use of process-derived gas oils can be used as quench oil to lower the temperature of the commercial separators. There was no increase in the rate of toluene insoluble formation as a result of the use of quench oils, which allowed the full advantage of the temperature decrease to be achieved. A qualitative comparison of the build-up of depos...
Quantitative description of the correlations between some characteristics (density, viscosity, asphaltene and sulfur contents, stability) of the vacuum residues and products of their visbreaking, and of the changes in the feed properties as a result of visbreaking in a real commercial visbreaker was done. The asphaltenes contents is higher in the petroleum products having higher density and viscosity. The higher the feed viscosity, the higher the visbreakate viscosity, but also the higher the relative decrease in the viscosity. There is no correlation between stability and the asphaltenes contents both for the feed and for the visbreakate. The higher the asphaltenes contents in the feed, the lower the relative increase in the asphaltenes contents during visbreaking. It indicates prevailing reactions of condensation of the asphaltenes precursors (resins, etc.) for the light stocks. For heavier stocks, cracking of the asphaltenes plays more significant role; starting from the asphaltene content in the feed of 7-9%, reactions of the condensation and cracking are approximately of the same rate, and increase in asphaltene content takes place mainly due to concentrating them in the visbreaking residue as a result of distillation of the visbroken product. Two groups of feedstocks may be defined from the point of view of their behavior in visbreaking: low-sulfurized (S<1%) and high-sulfurized ones (S>2%). In the feedstocks with low sulfur contents, the asphaltenes contents increases sharply, whereas for the high-sulfurized stocks the relative increase in the asphaltenes contents is low.
Conductivities of asphaltenes were measured as a function of concentration in solvents of varying permittivity. The molar conductivity was calculated assuming the molecular weight of asphaltenes to be 1000 g/mol.The Fuoss conductivity model was fitted to the experimental data with two free parameters i.e. the association constant and the molar conductivity at infinite dilution. The experimental data show indication of ion-pairs and strong dipole-ion interaction. Accordingly, the measurements were consistent with the model for ion pairs as given by Fuoss and multibody interaction theory given by Petrucci.At low concentration the asphaltenes consist mainly of free ions, as the concentration increases ion pairing leads to a decrease of the molar conductivity. At higher concentration ion-dipole interaction may lead to an increase of the molar conductivity, as is seen in some of the solvents. At even higher concentrations some indications of aggregation are observed.The results indicate that part of the asphaltenic fraction is ionized and behave as ions in solvents of low dielectric constant.
The solubility and insolubility of heavy oils and their fractions in dilute mixtures with various solvents were used to characterize heavy oil interactions. A two-dimensional solubility parameter, developed for the selection of solvents for organic polymers, was found to group all the solvents for each heavy oil fraction in polygon areas when the complexing solubility parameter component was plotted against the field force solubility parameter component. All fractions of Cold Lake vacuum residua, except for the saturate fraction, form concentric solubility areas. Therefore, in going in the direction of decreasing aromaticity from coke to asphaltenes to resins to aromatics, all solvents for the previous fraction in the series are also solvents for all subsequent fractions in the series. As a result, asphaltenes can be precipitated, but not extracted, from heavy oils. This is attributed to the interaction among polynuclear aromatics being the dominate interaction in petroleum that causes insolubility in hydrocarbon liquids. However, the paraffinic chains on the same petroleum molecules limit their solubility in highly complexing liquids. In contrast, even vacuum gas oils from the Exxon Donor Solvent coal liquefaction process are insoluble in aromatic liquids but soluble in moderately complexing liquids because of hydrogen bonding, resulting from oxygen functionality. Hydrotreating of these coal derived vacuum gas oils reduces their oxygen functionality and increases their solubility areas so that they become compatible with petroleum liquids.
Photothermal degradation of the latex obtained from Calotropis procera showed enhanced extraction in heptane up to 50%. Treatment of the latex with different concentrations of NaOH resulted in the reduction in heptane extraction of the latex. Treatment of latex with aqueous HCl coagulated it and thus resulted in an increase in extraction yield. The (1)HNMR, (13)CNMR and FTIR spectral analyses of treated latex showed an increase in the olefinic and carbonyl groups in the latex. Thus, this showed that photothermal treatments rendered the latex more amenable to hydrocracking for obtaining value added chemicals and fuels from the latex.
Experiments were conducted to study the effectiveness of a hydrogen donor solvent (tetralin) in a supercritical phase in controlling agglomeration and adhering tendency of a caking coal. It was observed that supercritical tetralin was as effective as tetralin in the liquid phase in controlling agglomeration and adhering tendency.
Sulfur standards were studied on a high resolution gas chromatograph (GC) ''HP 5890 series II plus'' Retention times were determined for each individual compound. A sample of straight run gas-oil (SRGO) was analyzed by coulomax method for total sulfur and by GC equipped with sulfur chemiluminescence detector (SCD) for individual sulfur identification. A database for about 165 sulfur compounds was established. Using relationship between total sulfur contents determined by coulomax method and sum of individual sulfur compounds determined by GC-SCD the quantity of different sulfur compounds in SRGO was determined.
ABSTRACT Presently, no definitive technique has been reported that measures the onset-of-precipitation of asphaltenes from a hydrocracker product at process conditions. In the present paper, a detection technique utilizing heat transfer analysis is presented. The method is suitable for the high temperature and pressure conditions in upgrading and is based on a heat transfer analysis of the precipitated layer. The modeling of the technique is provided, as well as details of the heat transfer vessel. Results from glycerol and corn oil model fluid experiments and simulations demonstrate the validity of the method Preliminary experimental results for Cold Lake bitumen are presented along with recommendations on how the method will be further improved.
Biomass pyrolysis oils were produced from stored biomass feedstocks by rapid pyrolysis in a fluidized bed reactor. The feedstocks used for these studies were switchgrass, corn stover, and hybrid poplar. The woody and herbaceous feedstocks were stored in chip piles and bales, respectively, unprotected in an open field for 6 months. At the end of the storage period. biomass samples were taken from the interior of bales and the centers of chip piles for pyrolysis studies. The materials were ground to pass -20/+80 mesh and dried to less than 10% moisture content before pyrolyzing in the fluidized bed reactor. Pyrolysis was conducted at 500 degrees C and with less than 0.4 s. vapor residence time. Total liquid yields were as high as 66% for the hybrid poplar and as low as 58% for the corn stover. Moisture content of the oils was between 10% and 13%. Gas and char/ash yields were 10-15% and 12-22%, respectively. The char/ash yields were feedstock dependent, but storage influence was significant for only the corn stover feedstock. Gas and liquid yields were not influenced by storage time. The oils were highly oxygenated and had higher heating values (HHV) of 23-24 MJ/kg that decreased slightly with storage time for all the feedstocks except the switchgrass. The oils, as currently produced, are high in ash and alkali metals. Ultimately, they will be upgraded and used as boiler and turbine fuels.
Hydrodenitrogenation of dilute solutions of North Gujarat Crude oil (an Indian Crude) has been carried out in a packed bed flow reactor. The reactions have been studied at a temperature range of 573K-723K and pressure 5.8 - 10.2 Mpa over commercial hydrotreating catalyst. From the analysis it was found denitrogenation rate is first order with nitrogen concentration and the total pressure of system.
The perchloroethylene coal refining process was used on North Dakota lignite coal. Effects of extraction time, perchloroethylene:coal ratio and artificial weathering were studied to determine their effects on the removal of organic sulfur. The artificial weathering conditions used were found to be too harsh and caused a decrease in the amount of organic sulfur removed, unlike normal weathering conditions. Additional studies were done involving various ligands, and showed that the addition of certain ligands during the process aided in the extraction of organic sulfur from the coal.
A microscopic study of the onset of asphaltene precipitation is reported. The onset conditions can be quantified by measurement of mixture refractive index, together with microscopic observations of particulate formation in mixtures of oil and precipitant, with or without added solvents. For isooctane mixtures with a variety of hydrocarbon solvents and a crude oil from Alaska, the onset of precipitation occurs over a narrow range of solution refractive index. Addition of polar solvents or different precipitating agents can shift the refractive index at which precipitation begins. Refractive index decreases when a crude oil is diluted by precipitant, as in this study, or when changes in temperature and pressure alter the relative molar volumes of species in the oil. If it falls below some critical value, resin/asphaltene aggregates that had been in stable dispersion become unstable and precipitate. These observations provide a method of screening solvents to differentiate between those that prevent precipitation mainly by maintaining a higher mixture refractive index and others that may participate in or disrupt asphaltene/resin interactions.
The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory. The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.
(1996). Review of: Anderson, K. B., and J. C. Crelling (Editors). “ Amber, Resinite, and Fossil Resins.” ACS Symposium Series No. 617. ISBN 0-8412-3336-5. Washington, DC: American Chemical Society, 1995. $79.95. Energy Sources: Vol. 18, No. 7, pp. 833-834.
The book develops the idea that a shift in the techno-economic paradigm creates opportunities for the rise of new firms, industries and countries to technological leadership, making the adoption of an
