Oxidation Of Bitumen Research Articles

OXIDATION OF BITUMEN IN THE PRESENCE OF A CONSTANT CONCENTRATION OF OXYGEN

ABSTRACT The rate of oxidation of bitumens oxidised in an approximately constant concentration of oxygen (300 psi air in a pressure vessel) can be accurately described by an equation derived assuming two concurrent simple first order reactions. The equation was successfully fitted to oxidation rate data obtained in terms of viscosity increase of neat bitumen under 300 psi of air at 60°C, 70°C and 80°C, and carbonyl group content in solution (6-15%) at 30°C. Bitumen oxidation can be generalised as consisting of a group of fast reactions obeying approximately first order kinetics, and involving carbonyl and sulphoxide formation and a much slower process involving carbonyl formation which is approximately constant over the experimental time frame. Parameters in the equation can be used as a simple means to compare the durability of bitumens oxidised at temperatures characteristic of field conditions.

Chemical and rheological evaluation of ageing properties of SBS polymer modified bitumens

The ageing properties of Styrene-Butadiene-Styrene (SBS) polymer modified bitumens were evaluated using Dynamic Mechanical Analysis (DMA), Gel Permeation Chromatography (GPC) and Fourier Transform InfraRed (FTIR) spectroscopy. The binders were aged by means of the Thin Film Oven Test (TFOT) and the Rolling Thin Film Oven Test (RTFOT), respectively. It was observed that ageing resulted in degradation of the SBS polymer (decrease in the polymer molecular weight) and oxidation of the bitumen (increase in the content of polar oxygen-containing molecules and increase in bitumen molecular weight). The polymer was observed to resist formation of sulphoxides. Changes in the rheological properties of aged-modified binders were dependent on a combined effect of bitumen oxidation and polymer degradation, which varied with bitumen source/grade and polymer type/content. In all cases, the aged modified binders showed better rheological properties than aged base bitumens. The study also indicated that the ageing index obtained using DMA was largely influenced by temperature and frequency. This parameter may be applied for evaluating the base bitumens and modified binders with a low polymer content (3% in this study), but not for modified binders with a high (6%) polymer content.

A Comprehensive Approach to In-Situ Combustion Modeling

ABSTRACT Low temperature oxidation (LTO) has long been recognized as one of the dominant mechanisms controlling fuel availability in in-situ combustion. Its effect on the physical properties of crude oils is also well known. In spite of these findings, the prevailing conceptual model of in-situ combustion still hinges on thermal cracking (in isolation) ahead of the firefront, to provide sufficient fuel (coke) for propagation of the reaction zone. Previous simulation studies, which purported to include LTO as part of the reaction scheme, have unrealistically specified the reaction products as carbon oxides and water. Furthermore, oil compositional changes due to oxidation have been completely neglected. This paper describes a unified pseudo-mechanistic reaction model for mathematical modeling of in-situ combustion of Athabasca bitumen. The model represents a consolidation of individual experimental kinetic studies on thermal cracking and low temperature oxidation of Athabasca bitumen, and reported data for the high temperature oxidation of coke. The formulation is comprehensive in that it allows bitumen to undergo density and viscosity increases, as well as reduced reactivity to oxidation, with increased oxidation extent. Hydrocarbon bypassing due to quenching of the combustion front is also permitted with the proposed kinetic model. The paper includes application of the reaction model in numerical simulations of adiabatic combustion tube tests performed on Athabasca bitumen. A significant feature of the model is its ability to predict the dual oxidation uptake peaks associated with ramped temperature oxidation experiments.

Use of rerefined oil distillation bottoms as extenders for roading bitumens

Vacuum distillation bottoms from the rerefining of waste automotive oils (WODB) can be successfully blended with standard petroleum bitumen to produce a stable binder with acceptable physical properties for roading applications. The increase in viscosity and shear susceptibility after accelerated ageing of thin films at 163°C is slightly less for bitumen extended with WODB than for bitumen itself; but at temperatures above ∼200°C the WODB appears to accelerate the rate of bitumen oxidation. Air blowing at 240°C can be used to produce an acceptable binder from blends of WODB and a softer grade of bitumen. The rate of hardening during air blowing depends on both the batch and concentration of WODB.

Application of calorimetry to investigations of kinetics and energetics of oxidation of fuels. Experimental and calculational methods for initial rates

A calorimetric method for obtaining isothermal initial rates of reaction (applied to oxidation of bitumen) is reviewed and a new method for carrying out calculations with thermograms from electrical calibration and chemical reaction experiments is presented.

Approche méthodologique directe et continue du processus d'oxydation des bitumes par spectroscopie infrarouge à transformée de Fourier

( Direct continuous method for studying oxidation of bitumens by Fourier-transform infrared spectrometry). The method is based on the standard rolling thin-film oven test with oxidation in air at 163°C. A specially designed infrared cell is used. FTIR spectrometry provides spectral fingerprints which are characteristic for each bitumen.

Kinetics and energetics of oxidation of Athabasca bitumen

Calcul de la vitesse d'oxydation a basse temperature (<350°C) du bitume pour le procede de combustion in situ, a partir de donnees experimentales representees par un modele mathematique simple. On distingue deux classes de reactions: oxydation partielle avec depot de coke a T<185°C et oxydation totale au-dessus

Oxidation reaction kinetics of Athabasca bitumen

The oxidation reaction kinetics of bitumen from Athabasca oil sands have been investigated in a flow-through fixed bed reactor using gas mixtures of various compositions. The system was modelled as an isothermal integral plug-flow reactor. The oxidation of bitumen was found to be first order with respect to oxygen concentration. Two models were examined to describe the kinetics of bitumen oxidation. In the first, the Athabasca bitumen is considered to be a single reactant and the oxidation reaction a single irreversible reaction. The activation energy for the overall reaction was found to be 80 kJ mol −1. This model is limited to calculating the overall conversion of oxygen. Because the fraction of oxygen reacting to form carbon monoxide and carbon dioxide increases with temperature, a more sophisticated model was proposed to take this into account. The second model assumes that the bitumen is a single reactant and that the oxidation of bitumen may be described by two simultaneous, parallel reactions, one producing oxygenated hydrocarbons and water, the other producing CO and CO 2. The activation energy for the first reaction was found to be 67 kJ mol −1, and for the second, 145 kJ mol −1. This more sophisticated model explains the result that at higher temperatures more oxygen is consumed in the oxidation of carbon, because this reaction has a higher activation energy than the reaction leading to the production of oxygenated hydrocarbons and water. This model can also predict the composition of the product gases at various reaction conditions.

Recovery of Water And Bitumen From the Athabasca Oil Sand Tailings Ponds(a)

Introduction Various methods to recover bitumen and water from the oil sand tailings pond were explored. It was shown that removal of free bitumen from the tailings tends to destabilize heavy sludges and also improves drying rates dramatically. Modification of the sludge pH using NaOH showed that improved settling took place only above pH-11. A heavy sludge was fractionated to yield a number of distinct mineral fines fractions, including a solid associated with the oil phase, a fraction which remained in colloidal suspension in the aqueous phase and a fraction which settled from the aqueous phase. All three solids contained significant quantities of organic matter. The oil-phase solid also showed considerable enrichment in heavy metals compared to the other solids. Introduction The hot water process used by Suncor and Syncrude to extract bitumen from the Athabasca oil sands produces large volumes of tailings(1,4). The raw feed consists of bitumen, sand, water and mineral fines. After discharging the tailings, the +44 µ particles settle out readily. When a substantial fraction of particles is present in a finer state of dispersion, aqueous sludges are produced(1) containing mineral fines(3), free and adsorbed bitumen(4), surfactants(5,6), bitumen oxidation products(7) and caustic soda. Although the settling behaviour of aqueous clay suspensions has been studied in detail, for instance, in connection with drilling muds(8), the settling of the tailings-pond sludges is generally not well understood. Recent studies have shown the settling to be non-Stokiam(3), with free and adsorbed bitumen perhaps playing a key role(4). Also, the presence of fine clay platelets, because of their differential edge and face-wetting properties, possibly assists in the stabilization of the suspensionst(3,4). As the recycle water for the extraction process cannot contain more than - 5% solids, a large volume of the tailings must be stored in ponds of ever increasing volume. Some settling occurs to permit re-use of the uppermost pond layer only. With the continuing use of water required for the increased production of bitumen from the Athabasca oil sands, interest in recovering process water is mounting(2,4). From an economic point of view, the recovery of additives, such as caustic soda, and residual bitumen is significant in considering any water recovery process. In this communication, we describe various experiments carried out to study and improve the settling behaviour of the sludges. These experiments include free settling with pH modification evaporation and some simple forms of pretreatment to recover bitumen. In addition, we investigate the nature of the fines present in the tailings-pond sludge. Experimental Aqueous tailings in 5-gallon to barrel-size lots were obtained from the Suncor plant sludge pond, and contained 5–12% solids by weight, although in some lots the solids content ranged as high as 30%. Solids contents were obtained by drying aliquot samples to constant weight at 110°C. The organic content of oven-dry samples was determined using several methods, including toluene extraction, loss on ignition (LOI) at 450°C and carbon determination by combustion followed by gravimetric measurement of evolved CO2.

Influence of metal salts on bitumen oxidation

Oxidation of bitumen with air or oxygen at various temperatures significantly alters the composition of the material and markedly reduces asphaltene solubility. Similar and, in many instances, more noticeable effects are produced in the presence of metal salts. Throughout the various processes, oxygen incorporation usually occurs into those fractions which are relatively high in hetero-atom (nitrogen, oxygen and sulphur) content. Spectroscopic examination of the products allows feasible representation of the predominant pathways of bitumen oxidation as well as possible modes of asphalt deterioration.

Oxidation of bitumen in relation to its recovery from tar-sand formations

Simple chemical reactions are described which bring about modification of the components of a bitumen. This is accomplished by using an oxygen-containing gas and subsequent treatment with alkali solutions of sulphites and/or bisulphites. The resulting water-soluble sulphonated bituminous derivatives have significant emulsifying and dispersing powers and are likely to be of use in extracting the bitumen in situ.

Decontamination of the gases evolved during continuous oxidation of bitumen

Decontamination of the gases evolved during continuous oxidation of bitumen

Effect of radiation intensity on photo‐oxidation of an air‐blown bitumen

AbstractXenon‐arc irradiation was used to study the influence of a wide range of radiation intensity on the rate of photo‐oxidation of a sample of air‐blown bitumen as determined by infra‐red spectroscopy. The xenon‐arc was monitored to provide information on its rate of decay, and its range of intensity was compared with that of total solar radiation in Melbourne. Thermal (dark) oxidation rates were also determined at various temperatures. The information obtained is discussed in terms of the mechanism of photo‐oxidation of bitumen and the relation to climatological data. Acceleration factors for oxidation of bitumen in the laboratory for prediction of durability were determined by applying the superposition principle to the data.

An analytical equation for the statics of continuous production of oxidized bitumens

Equations are derived for the statics of continuous oxidation of bitumen in a one-flow vertical tube reactor with recirculation. They can be used in designing the process plant and for analyzing the system in case of unplanned problems.

Influence of radiant energy source on bitumen oxidation

AbstractBy use of the steady change in infra‐red absorption of the carbonyl functional groups of bitumen with increase of radiant energy flux, the oxidation rates of four air‐blown bitumens of coating grade have been obtained for the three sources of radiation, carbon arc, xenon arc, and sunlight. Differences in the pattern of oxidation for the much used carbon arc compared with both xenon‐arc and solar irradiation were found, whereas the last two sources induced nearly identical behaviour in the bitumens. Continuous measurement of the intensity of the solar radiation by pyroheliometry has indicated that the oxidation rates are directly proportional to intensity, sensitive to very low intensities and independent of diurnal changes. Potassium ferrioxalate dosimetry has shown that the intensity of the xenon‐arc irradiation as used in a weatherometer simulated that of summer sunshine extremely well, whereas the carbon‐arc irradiation, as used in the ASTM method of evaluation of weatherometer durability of bitumens, had a fivefold greater intensity. This increased intensity changed the pattern of rate of bitumen oxidation rather than simply accelerating the steady‐state oxidation rates.

Rates of oxidation of petroleum asphaltenes and other bitumens by alkaline permanganate

Rate of oxidation by alkaline permanganate has been used by a number of investigators for comparison of coals, oil shales, and related natural bitumens, and to provide an insight into their molecular structures. The method is equally applicable to petroleum asphaltenes. To facilitate additional studies, a semi-automatic titrating and recording apparatus has been designed and constructed. Twentysix samples, comprising coals, oil shale, gilsonites, manjak or glance pitch, natural graphite, asphaltenes from crude oils and refinery fractions, and the insoluble carbonaceous material in marine and non-marine rocks, have been examined. Oxidation rates of the coals and petroleum asphaltenes vary by a factor of more than 500 and in general show a rough correlation with the oxygen content of the organic material.