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In the alkaline system, the iron complex was used to absorb hydrogen sulfide to obtain sulfur, and the iron complex absorbent was oxidized and regenerated at the anode by electrolysis method for recycling, and hydrogen was obtained at the cathode. This process can recover both hydrogen and sulfur from hydrogen sulfide and avoid the harsh conditions of strong acidity. In this paper, SPE electrode is used in the oxidation and regeneration process of iron complex. The results show that the oxidation current density of iron complex at SPE electrodes are one order of magnitude higher than that of traditional electrodes, and the current efficiency is slightly lower than that of traditional electrode. The current efficiency of carbon cloth SPE electrode reaches 90% from 0.25 to 0.5V, the performance of complexed iron oxidation is better than that of the stainless-steel mesh SPE electrode, and the side reaction is mainly EDTA oxidation reaction.

A high-sulfur (4.69 wt%) crude oil was discovered in the China Bohai Bay Basin which is known to contain low sulfur crude oil. The composition of this high sulfur crude oil and its geological origin are unknown. In this study, thiophenic and sulfidic sulfur compounds were isolated from the crude oil by methylation/demethylation and characterized using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography-mass spectrometry (GC–MS). Relatively high abundance of sulfur compounds with 30 carbon atoms and 5–7 double bond equivalence (DBE), which were assigned to sulfurated steranes with thiophene or tetrahydrothiophene moieties. Some of these compounds have not been reported in fossil fuels. In addition to commonly found sulfur compounds in petroleum feedstock, such as benzothiophenes and dibenzothiophenes, other structural sulfur compound types were detected: long-chain 2,5-di-n-alkylthiolanes, 2,5-di-n-alkylthianes, bicyclic terpenoid sulfides, isoprenoid thiophenes, and isoprenoid benzothiophenes. The presence of abundant biomarker sulfur compounds suggests that the sulfuration of the high sulfur crude oil was occurred in the early diagenesis stage instead of a thermochemical sulphate reduction (TSR) process.

Recovery hydrogen from hydrogen sulfide is an effective way of utilizing exhaust gas. In this paper, removal of hydrogen sulfide by indirect electrochemical process was studied using acidic aqueous solution of Fe3+/Fe2+ as the electrochemical intermediate. Solid polymer electrolyte was applied to hydrogen production by indirect electrolysis of H2S, in which the anode was graphite cloth, the cathode was the platinized graphite cloth, and the membrane was proton exchange membrane. The results of electrolysis experiments showed the relationship of current density as a function of electrolytic voltage at constant flow rate of electrolyte, temperature, and electrolyte composition. The effect of the cathode liquid velocity on current density was small. When the flow rate of anode electrolyte was greater than 200 L/hr., the current density tended to be stable. When [Fe3+]>0.20 mol/L, the concentrations of Fe2+ and Fe3+ ions in the anode solution had no significant impact on the current density. The current density gradually increased with temperature. In the electrolytic process of hydrogen production, the Fe2+ ions diffused from the anode to the cathode. The amount of diffusing Fe2+ ions gradually increased with time. The effect of Fe2+ ions diffusion from anode to cathode on hydrogen production was discussed.

Forecasting of the gasoline demand is a key issue for refineries in China. Some international energy organizations (IEOs) and international oil companies have estimated the gasoline demand in China for the next 20 years. These organizations and companies used the assumptions that the technology of clean-energy vehicles do not gain significant progresses, and they do not consider the trends of policy changes of different provinces in China. So the forecast of IEOs (international energy organizations) may not reflect the real trend of gasoline demand in China. In this paper, we considered more stringent regional environmental regulations and the possibility of technological progress in clean-energy vehicles, using the bottom to up method to estimate the gasoline demand of all 30 provinces in China, adding them up, to gain the forecast of total gasoline demand in China for the next twenty years. The result shows that gasoline demand will increase slower and decrease faster than the estimation of some mean IEOs (international energy organizations).

Electrochemical reduction desulfurization is a low cost, environmental friendly technology which is capable of achieving a high degree of automation. Electrochemical coupling reactions of organic sulfur hydrogenation and water electrolysis on the C/Nafion electrodes were performed. The electrochemical desulfurization was determined by cyclic voltammetry (CV), bulk electrolysis with coulometry (BEC) and electrochemical impedance spectroscopy (EIS) techniques. Thiophene and benzyl mercaptan were used as model organic sulfur compounds. The results of cyclic voltammetry showed that the electrochemical hydrogenation reduction reaction of thiophene occurred at about −0.35 V. The process included proceeding chemical reaction and electrochemical reaction. The currents generated from thiophene hydrogenation reactions increased with the reaction temperature and the H + concentration of the electrolyte acidity of anode. Under the same reaction conditions, the desulfurization efficiency of benzyl mercaptan was significantly higher than that of thiophene. From the products of electrolytic reactions, the mechanisms of electrochemical hydrogenation of thiophene were proposed, consisting of two pathways: ring opening followed by hydrogenation and directly hydrogenation followed by ring opening. The proposed reaction mechanisms were consistent with the EIS results, indicating the predominant reactions were ring opening followed by hydrogenation. The reaction products and EIS results suggested that the reaction mechanisms of electrochemical hydrogenation of benzyl mercaptan were by breaking C S bond to form H 2 S and toluene.

Catalytic deoxygenation of fatty acids to alkanes is an ideal route to produce biodiesel with high heating value. However, traditional transition-metal sulfide and noble metal catalysts are sulfide-contaminated, high cost, or easily poisoned. To overcome the above issues, this work developed a non-noble and sulfide-free reduced transition-metal composite NixNbyOz, which was effective to selectively hydrogenate stearic acid, a typical fatty acid model compound, to diesel-range alkanes. By using a simple slurry method, reduced NixNbyOz catalysts have been successfully prepared with an outstanding catalytic performance. The results showed that catalyst Ni0.5Nb0.5Oz effectively converted stearic acid to n-alkanes with nearly 100% conversion and >99% n-alkanes selectivity at mild conditions (513 K and 3.5 MPa of H2 pressure). Appropriate Nb species improved the dispersion of Ni species, which may supply more hydrogenation active sites. Two possible reaction routes of stearic acid were proposed, and the hydrogenolysis of stearyl stearate was confirmed as the rate-determining step based on the kinetics experiments. Because of moderate acidity of Nb species, the ratio of C17/C18 alkane was not markedly affected by reaction conditions when the conversion of stearic acid was higher than 99%. Moreover, catalyst Ni0.5Nb0.5Oz showed a high recycle ability and compatibility for other long-chain fatty acids, demonstrating that catalyst Ni0.5Nb0.5Oz is a promising green catalyst for producing biodiesel from fatty acids.

Delayed coking is a common resid conversion process used in refining operations. A large amount of oil-containing wastewater is produced during the hydraulic decoking process. The coking wastewater contains emulsions which are difficult to process in water treatment plants, especially when the coker is fed with feedstocks have high content of heteroatoms. This study examined the molecular composition of emulsified oil and dissolved organic matter (DOM) in coking wastewater. The emulsification agents in coking wastewater were identified. The emulsified oil and DOM were separated and enriched by liquid–liquid extraction, solid phase extraction, and adsorption chromatography, and then characterized by gas chromatography-mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry analyses. The results showed that the emulsified oil and DOM in coking wastewater contained highly condensed molecules with a large number of nitrogen and oxygen heteroatomic compounds. The OxSy surfactants and their derivatives, polyoxyethylene ether, and the strong polar oxygen-, nitrogen-, and sulfur-containing compounds are likely the oil–water emulsification agents.

Co-Mo sulfide catalysts with different particle size and structures were prepared in ethanol-water mixed solvent followed by a low-temperature sulfurization process, and were tested in dibenzothiophene hydrodesulfurization. The effects of the ethanol/water ratio on the particle size of precursors, active phase composition, active site number, morphology, and hydrodesulfurization activity of the final catalysts were investigated. The atomic ratio of Co/Mo and active phase morphology of catalysts closely relate to the dielectric constant of ethanol-water mixed solvent. Appropriate dielectric constant favors the formation of (Co)MoS2 slabs with shorter length (∼ 5.0 nm) and higher stacking number (∼ 4.3 layers), resulting in more coordinatively unsaturated sites, especially in the corner sites. The catalytic activity not only depends on the active sites of CoMoS phase, but also on that of Co9S8 and MoS2 phases because of synergistic effect. For MoS2 and CoMoS phases, the corner sites show higher direct desulfurization activity than the edge sites.

Apodization is a generally applied signal processing method in FT-ICR MS (Fourier transform ion cyclotron resonance mass spectrometry) analysis for complex petroleum samples that is used to lower the spectral leakage and smoothen the spectrum line shape. Present study evaluates the effect of apodization on the FT-ICR MS results through a systematic examination on both simulated and actual heavy petroleum signals. The result shows that the resolving power, instead of the dynamic range, is the key factor for heavy petroleum FT-ICR MS analysis due to the severe peak overlapping. Window functions with high dynamic range will reduce the resolving power so that many of the species cannot be detected. The improvement on accuracy of apodization with peak intensity is negligible and all the window functions have similar intensity error. Low dynamic range window functions perform better for FT-ICR MS analysis since they have less resolving power reduction and the spectral leakage is eliminated to ensure correct peak selection. Sine-bell and low beta value Kaiser window functions are recommended for complex mixtures.

Au/Nafion/Pt electrodes were used in the coupled reaction system of benzene hydrogenation and water electrolysis for hydrogen production and storage. Au/Nafion/Pt electrodes with the short electrode spacing reduce hydrogen evolution and increase current density and current efficiency. The morphology of metal layer surface of electrodes and electrochemistry hydrogenation reactions were studied. The results showed that the morphology and conductivity of metal layer surface of electrodes were related to the reduction reaction rate of metal complex in the electrode preparation process. The Au complex reduction reaction rate and Au deposition rate were lower than Pt complex reduction reaction rate, yielding a dense smooth Au surface which had low resistance and was not conducive to the diffusion of H + . Benzene hydrogenation reaction rate increased and current efficiency decreased with increased electrode potential. The effect of electrode potential on current efficiency was similar for all electrodes tested. Au/Nafion/Pt electrodes had the highest current efficiency and current density among the electrodes tested; the current density of benzene hydrogenation was higher than 100 mA/cm 2 and 90% current efficiency.

The use of hydrogen in benzene–water system which combines water electrolysis and hydrogenation in a polymer electrolyte cell was carried out as a means for seasonal storage of electricity. Gas diffusion electrodes were effective in improving coupled reactions of electrochemical benzene hydrogenation and water electrolysis. The reaction kinetics for the electrochemical hydrogenation process using gas diffusion electrodes was investigated by evaluating current efficiency and reaction rate. The results showed that the rate of hydrogen evolution was higher than the rate of benzene hydrogenation and the apparent activation energy of hydrogen evolution was lower than that of benzene hydrogenation. As the electrode potential increased, the hydrogen evolution rate increased. The benzene hydrogenation reaction rate reached a maximum at −0.8 V electrode potential, then decreased slightly. The current efficiency, however, reached its maximum at −0.7 V. Modifying electrodes by adding 0.2 wt% polyethylene glycol (PEG6000) reduced the mass transfer resistance of organic phase (cyclohexane/benzene) and improved the hydrogenation reaction rate.

TiO 2 -Al 2 O 3 binary oxide supports were obtained by sol–gel methods from Tetra- n -butyl-titanate and pseudoboehmite/aluminium chloride resources. The typical physico-chemical properties of NiW/TiO 2 -Al 2 O 3 catalysts with different TiO 2 loadings and their supports were characterized by means of BET, XRD and UV–vis DRS, etc. The BET results indicated that the specific surface areas of NiW/TiO 2 -Al 2 O 3 catalysts were as higher as that over pure γ-Al 2 O 3 support, and the pore diameters were also large. The XRD and UV–vis DRS analyzing results showed that the Ti-containing supported catalysts existed as anatase TiO 2 species and the incorporation of TiO 2 could adjust the interaction between support and active metal, and impelled the higher reducibility of tungsten. The hydrodesulphurization (HDS) performance of the series catalysts were evaluated with diesel feedstock in a micro-reactor unit, and the HDS results showed that NiW/TiO 2 -Al 2 O 3 catalysts exhibited higher activities of ultra deep hydrodesulphurization of diesel oil than that of NiW/Al 2 O 3 catalyst. The optimal TiO 2 content of NiW/TiO 2 -Al 2 O 3 catalysts was about 15 m%, and the corresponding HDS efficiency could reach to 100%. The sulphur contents of diesel products over NiW/TiO 2 -Al 2 O 3 (from pseudoboehmite/AlCl 3 ) catalysts with suitable TiO 2 content could be less than 15 ppmw, which met the sulphur regulation of Euro IV specification of ultra clean diesel fuel.

Variability in ore composition and process parameters is known to affect bitumen recovery from natural oilsands. In this work, we extend our earlier studies with model oilsands (MOS) systems to investigate the effects caused by the presence of asphaltene and divalent cations on the interaction between bitumen and silica particles. The absence of both asphaltene and fines was found to have significant effects on bitumen recovery. With a typical oilsands, addition of small amounts of caustic improves recovery but overdosing causes a drastic loss of yield through bitumen emulsification. Without asphaltene and in the presence of fines, the typical drop in bitumen recovery above pH 10 did not occur, indicating that the source of emulsifying agents had been eliminated. With deasphalted bitumen, recovery in the absence of silica fines was very poor at all NaOH dosages. The strong, negative effect of divalent cations on “normal” bitumen recovery was almost completely eliminated when asphaltene was absent.

Variability in ore composition and process parameters is known to affect bitumen recovery from natural oilsands. In this work, we extend our earlier investigations with model oilsands systems (MOS) to determine the effects of calcium, magnesium and bicarbonate ion concentrations in the process water and their interactions with ‘active’ solids such as: kaolinite, montmorillonite and ultra-fine silica. Our results demonstrate that solids mineralogy and decreasing particle size produce negative outcomes on bitumen recovery related to concomitant effects on bitumen droplet size during flotation. In some cases, certain process water chemistries were found to restore recovery, but clay concentration was the key factor. Naturally acidic oilsands are known to give poor bitumen recoveries. An MOS prepared with connate water at pH 2 responded in the same way. Comparison with a typical oilsands showed no significant differences in middlings pH and the large, negative effect on bitumen recovery was not reversed by higher caustic loading during separation. This result may be caused by irreversible co-flocculation of bitumen and mineral particles during preparation of the MOS and may reflect similar behavior in comparable natural samples.

The typical physico-chemical properties and their hydrodesulfurization activities of NiMo/TiO 2 -Al 2 O 3 series catalysts with different TiO 2 loadings were studied. The catalysts were evaluated with a blend of two kinds of commercially available diesels in a micro-reactor unit. Many techniques including N 2 -adsorption, UV-vis DRS, XRD, FT-Raman, TPR, pyridine FT-IR and DRIFT were used to characterize the surface and structural properties of TiO 2 -Al 2 O 3 binary oxide supports and the NiMo/TiO 2 -Al 2 O 3 catalysts. The samples prepared by sol-gel method possessed large specific surface areas, pore volumes and large average pore sizes that were suitable for the high dispersion of nickel and molybdenum active components. UV-vis DRS, XRD and FT-Raman results indicated that the presence of anatase TiO 2 species facilitated the formation of coordinatively unsaturated sites (CUS) or sulfur vacancies, and also promoted high dispersion of Mo active phase on the catalyst surfaces. DRIFT spectra of NO adsorbed on the pure MoS 2 and the catalysts with TiO 2 loadings of 15 and 30% showed that NiMo/TiO 2 -Al 2 O 3 catalysts possessed more CUS than that of pure MoS 2 . HDS efficiencies and the above characterization results confirmed that the incorporation of TiO 2 into Al 2 O 3 could adjust the interaction between support and active metals, enhanced the reducibility of molybdenum and thus resulted in the high activity of HDS reaction.

Narrow fractions of Athabasca oil sands-derived synthetic crude oil (SCO) from Canada were obtained by distillation at 20 °C to 500 °C and characterized. The yield and properties, such as density, refractive index, viscosity, freezing point, sulfur and nitrogen content and UOP K-index, were correlated as a function of boiling temperature (Tb). The properties of naphtha fractions, jet fuel and diesel fractions could be predicted accurately with the correlations, which are useful for process design considerations, such as optimizing operating conditions of refinery processing units. The other key properties and characteristics of naphtha fractions, jet fuel, diesel and vacuum gas oil were also determined.

Heavier oils are becoming increasingly important as a refinery feedstock. In order to optimize quality and yield of products from the vacuum residues of these intractable feeds, more information on their molecular chemistry is required. Super-critical fluid extraction and fractionation (SFEF) with pentane provides the opportunity to cut deep into the bottoms while readily yielding enough of each fraction to allow characterization and reactivity studies. Results show that problematic species and SARA components (saturates, aromatics, resins and asphaltenes) are asymmetrically distributed among the separated fractions. The determination of average structures based on bulk analysis of the whole residue is heavily biased towards the lighter fractions and provides little information on heavy, difficult to process components. A comparison of bitumen pitch with residues from benchmark crudes, heavy oils and bitumen from non-Athabasca sources, demonstrates that it is not significantly different in its chemical make-up or reactivity to other hydrocarbons. Compared to conventional oils, the intractable nature of bitumen can be largely ascribed to its much higher asphaltene and contaminant contents.

Supercritical fluid extraction and fractionation (SFEF) has been used to separate a variety of petroleum residua and other heavy oils into narrow-cut fractions with total yields up to 75–90%. Any insoluble material, or end-cut, corresponds to the asphaltene fraction in the parent oil. The narrow-cut fractions were analyzed comprehensively and separated into the solubility classes of saturate, aromatic, resin, and asphaltene fractions. The boiling points were measured up to 700 °C and correlations were established with the key factors such as density and molecular weight. This allows extrapolation of boiling points of residue fractions up to 1000 °C. Unlike bulk property measurements, the narrow-cut characterization data show increasing concentrations of key contaminants as the fractions become heavier. The solubility parameter for each narrow-cut fraction was measured using high-pressure fluid phase equilibrium with propane. The corresponding values for the end-cuts were obtained by the conventional precipitation method. The distribution and reactivity of sulfur species were determined by XPS in the bitumen pitch fractions and the corresponding residua produced during thermocracking and hydrocracking. The average structures for the narrow-cuts were constructed from molecular weight and elemental analyses together with FTIR, 1 H-NMR and 13 C-NMR data. The results were used to develop a generalized feedstock characteristic index, K R . This index shows good correlation with feedstock hydrocarbon constituents and can be used to assess feedstock reactivity and processability. Downstream refiners can use the narrow-cut data and K R values for process optimization by either cutting deeper into residua bottoms to increase yield or by selecting the most appropriate process units for the various residue fractions. This information can also be used by upstream operators to determine the economic feasibility of utilizing the end-cut onsite.

The bulk of bitumen recovery from oilsands takes place via a flotation/settling process in the primary separation vessel (PSV). Under certain conditions, some oilsands slurries become non-segregating, i.e. both fines and coarse solids remain in suspension and little or no bitumen froth is generated. An ultra-fine ( In this work we determined the amounts of ultra-fines in oilsands from different depositional environments. Although a generally linear correlation exists between ultra-fines and fines or clay contents, some samples were found to have a disproportionately high ultra-fines contribution relative to other oilsands. Waste units, in particular, were found to be extremely rich in the ultra-fines and clay-sized fractions. We used a 2 H NMR method to measure both the rate and degree of gelation of ultra-fines suspensions separated from oilsands. Sludging conditions are reached when the ultra-fines concentration is between about 1.5 and 2.0 w/w%. Measurement of ultra-fines gelation times showed them to be of the same order as slurry residence time in the PSV. Laboratory jar tests have demonstrated that poor segregation of oilsands components can be correlated with the gelation conditions determined by NMR measurements.

Gas oil streams from the upgrading of oilsands bitumen contain toluene insoluble, gummy, solid foulants that cause process problems by plugging hydrotreater feed filters and catalyst beds. From a process optimization standpoint, it is of considerable interest to determine the exact origin and nature of this material in order to design remedial measures. We selected coker heavy gas oil (KHGO) from bitumen upgrading as the primary test material for this work but also include samples from other parts of the process. Typically, solids content of gas oils are determined by a filtration method. For the KHGO sample used here, this approach yielded a value of 45 ppm. We also compared solids content using ultra- and low-speed centrifugation techniques. With toluene as the diluent, both of these centrifugation methods gave virtually the same toluene insolubles (TI) value, i.e. 24 and 23 ppm, respectively. For paraffinic diluents the measured TI contents ranged from about 50 to 200 ppm. Our results demonstrate that KHGO may contain significant amounts of TI not measured by conventional filtration. Characterization of gas oil TI from different sampling points in the bitumen upgrading circuit showed that it is a nitrogen and oxygen rich organic material, associated with minor amounts of inorganic elements representative of ash-forming iron minerals and alumino-silicate clay. The most likely source for this intractable toluene insoluble fraction appears to be a low molecular weight pyrrollic species present in heavy gas oil. Such compounds are easily oxidized to produce insoluble polymers that can interact with inorganic minerals and metals, producing gummy material capable of blinding filters.

Chinese Dagang atmospheric residue, Arabian light and medium vacuum residues were subjected to supercritical fluid extraction and fractionation (SFEF). Each residue was fractionated into eight narrow extractable fractions with increasing molecular weight (MW) and polarity, and a non-extractable end-cut. Catalytic hydroprocessing of residue SFEF fractions were carried out in a 100 ml autoclave in the presence of two crushed, commercial Ni–Mo catalysts. Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactivities decreased as the MW and/or aromaticity of residue fraction increased. Decreased HDS and HDN reactivities were due to increased diffusion resistance and decreased intrinsic reactivity, respectively. Even though the properties of residues varied, coke yield, sulfur and nitrogen removal data for all SFEF fractions correlated well with the recently proposed feedstock characteristic index, KH. Sulfur and nitrogen removals for SFEF fractions with KH value less than 6, were comparable to those in thermal cracking. The heavy fractions, especially the end-cut, inhibit catalytic reactivity of the light fractions. As a result, use of the bulk sample analysis for the whole residue is misleading to determine the reactivity of residue. The SFEF end-cut was the most refractory fraction of the residue, which had a much higher coking propensity than all the SFEF fractions. Product gas yields were similar for all SFEF fractions, except for the end-cut which was 50% higher. As the SFEF fractions became heavier, the coke yield increased at the expense of light and middle distillate yields. The performance of two commercial catalysts was similar.

The average molecular structure of coker heavy gas oil (HGO) from Athabasca bitumen was derived from both elemental properties and 1 H and 13 C NMR spectra. The optimized 3D structure of the most stable conformation was obtained by quantum chemistry calculations, together with molecular mechanics and molecular dynamics simulation methods. The relative structural parameters and characteristics were simulated through a quantum chemistry study. The adsorption and hydrotreatment of HGO molecules on catalyst surfaces were studied in combination with the nano minicrystal catalyst model. The stable minimum of adsorption was reached when the HGO molecule was 0.22 nm from the catalyst surface. The exothermic heat of adsorption is 378.0 kcal/mol. Molecular simulation of HGO hydrotreatment shows that the total system energy changes as a hydrogen atom approaches the reaction site of an HGO molecule. The activation energy and the heat of reaction for the initial hydrotreatment reaction are 133.8 and −176.0 kcal/mol, respectively.

Bitumen derived gas oils have unique properties and are difficult to hydrotreat. These gas oils also significantly deactivate conventional catalysts; new, alternative catalysts have shown only limited improvements. The key for process and quality improvements is a better understanding of the molecular chemistry of gas oil. The approach applied in this work involves a combination of gas oil fractionation by high performance liquid chromatography (HPLC) and analysis of the resulting fractions by advanced spectroscopic methods. Results show that the HPLC saturate fraction is practically free of aromatic components. The nominal mono- and di-aromatics fractions differ in that the former has a higher molecular weight and H/C ratio but lower aromaticity and heteroatom content. The HPLC three poly-aromatic sub-fractions comprise molecules with an average of only two aromatic rings. Also, the H/C ratio and aromaticities of these samples are virtually the same. Regardless of their structural resemblances they differ substantially in their HPLC elution behaviour. This can be attributed to the differences in their oxygen and, especially, nitrogen contents. The asymmetric distribution of nitrogen may allow its selective removal thus opening the possibility for less expensive treatment, especially in terms of catalyst utilisation.

Natural oilsands is a complex mixture of sand, clay, bitumen and connate water that can vary markedly from one sample to another. Also, oilsands processability is known to depend on composition and process water chemistry. Because these variables are hard to control, the effect of an individual oilsands component on bitumen recovery is difficult to determine. Here, we carry out a series of systematic screening experiments with model oilsands (MOS) to determine the effects of system components and water chemistry on bitumen recovery using a warm slurry extraction process. Atmospheric topped, blended or deasphalted bitumen were used at a constant level of 10-wt% in the preparation of the model systems. The solids components tested included: different size fractions of silica sand, and several commercial clay minerals, including illite, montmorillonite and kaolinite. Clay concentrations were varied up to 5-wt% of the total solids. Anions and cations at concentrations comparable to those in process water from a commercial oilsands extraction plant were also evaluated. Bitumen recovery results from these screening tests were compared with those for a base case, or standard, MOS mix comprising 10-wt% atmospheric topped bitumen, 21-wt% silica fines and 5-wt% deionized water at pH 8; coarse silica sand provided the balance to 100-wt% of solids, or 64-wt% of the MOS. Recovery results for the different screening test variables were classified into three categories: (1) Bitumen recoveries comparable to those for the standard MOS, i.e. size of coarse solids, bitumen type, sodium, chloride and sulfate ions. (2) Decreased bitumen recovery, reversible by addition of more NaOH, i.e. size/amount of fine solids and illite. (3) Bitumen recovery that could not be reversed, i.e. synthetic hydrophobic coarse solids, montmorillonite, kaolin, calcium and magnesium ions.

Incipient coke formation was studied during heating of Athabasca pitch (+524 °C), heavy gas oils, their mixtures, and both distillation and solvent fractions in isothermal batch reactors at atmospheric pressure. Samples of about 1.5 g were reacted in open glass lined reactor tubes at temperatures from 360 to 420 °C over times from 0.3 to 7 h. Toluene insolubles and volatiles were measured in all experiments, with asphaltenes and heptane solubles in selected cases. Kinetic data are presented for toluene insoluble formation; results for pitch appear to follow the Wiehe series model for coke formation. The composition of the toluene insolubles formed is shown to depend on reaction severity.

Supercritical fluid extraction and fractionation was used to prepare narrow-cuts from a variety of petroleum vacuum residua. The narrow-cuts were subjected to comprehensive characterization and solubility class separation into saturates, aromatics, resins and asphaltenes fractions. Unlike the bulk property measurements, the narrow-cut characterization data show uneven distribution of key contaminants (with the concentration increasing) as the fraction becomes heavier. Narrow-cut data were used to develop a generalized feedstock characteristic index, KR, that correlates well with the feedstock hydrocarbon constituents and can be used to assess feedstock reactivity and process capability. Downstream refiners can use the narrow-cut data and KR index for process optimization by either cutting deep into the bottom of residua to increase yield or selecting appropriate process units for various residue fractions. Narrow-cut data were also used to develop critical properties of residue fractions, which can be used as input parameters for simulation studies in designing process units for heavy crude and residua.

The Canadian oil sands deposits in northern Alberta contain about 1.3 trillion barrels of crude oil equivalent. The largest of the four major formations is found in the Athabasca region where bitumen is heterogeneously distributed throughout an unconsolidated mineral matrix. About one-tenth of the oil sands in this deposit is economically recoverable by conventional surface mining techniques. The Hot Water Extraction Process (HWEP) is used commercially to recover bitumen from surface mined oil sands ore. The viability of this process relies on the existence of a thin water film around each solid particle in the ore matrix. However, a completely water-wet mineral condition is not generally the case for oil reservoirs, including oil sands deposits. In the latter case, it has been shown that certain solid fractions are associated with significant amounts of toluene insoluble organic matter (TIOM), physically or chemically adsorbed onto particle surfaces. These fractions are generically described as ‘organic rich solids’ (ORS). In bitumen separation processes, the organic matter associated with various ORS fractions represents an impediment to optimum bitumen separation and upgrading. In this sense, these solids are considered to be ‘active’ relative to the ‘inactive’ water wetted quartz particles comprising the bulk of the oil sands ore. Preliminary results indicate that the ORS content of an ore appears to be a better predictor for ore processability than the traditional use of bitumen or fines (−44 μm) contents. Two types of ORS have received particular attention. The first is a coarser fraction, usually less than 44 μm but also occurring as particles greater than 100 μm in diameter. This material typically occurs as aggregates of smaller particles bound together by humic matter and precipitated minerals. During the bitumen separation process, these heavy aggregates carry any associated bitumen into the aqueous tailings, thus reducing overall bitumen recovery. The second important fraction comprises very thin, ultra-fine clay particles with a major dimension of

Natural oilsands deposits are composed of a complex mixture of sand, silt, clay, water and bitumen. The bitumen content and silt fraction, or fines (

Compared to benchmark crude oils, bitumen does not respond well to conventional upgrading processes. In order to improve our understanding of this problem, we compare the chemical and physical properties of fractions from super critical fluid extraction of bitumen pitch with the corresponding fractions of residua from Venezuelan heavy oil, a Saudi Arabian light crude and a Chinese Daqing conventional crude. Relatively minor differences in chemical structure were observed between the corresponding residua fractions from Athabasca bitumen, Venezuelan heavy oil and Saudi Arabian light crude. Only the Chinese Daqing showed significant variance; this sample is much more aliphatic and has greater geometrical dimensions than the corresponding samples from the other residua. The end-cut from Athabasca bitumen pitch contained ultra-fine solids together with much higher levels of nickel, vanadium and nitrogen than the conventional crude end-cuts. These components are among the most intractable in upgrading and could be responsible for the problems encountered in bitumen upgrading, especially by catalytic processes.

As the Canadian supply of light crudes has diminished in recent years, refineries have necessarily been required to deal with difficult to process oilsands bitumens and heavy oils. Bitumen in particular exhibits unique behavior during upgrading; nearly 50% (w/w) of the feedstock is an intractable residuum. The fast catalyst deactivation and high coke forming propensity displayed by this feedstock have been attributed to the asphaltene and associated solids contents of extracted bitumen. The variability of these intractable components in bitumens from mined and in-situ Athabasca oilsands were examined and compared with bitumens from Nigerian and Utah oilsands. Except for the in-situ bitumen, all of the samples were found to contain significant amounts of fine solids. Unexpectedly, the in-situ bitumen also contained the least amount of asphaltene and the highest amount of the intractable heteroatoms nickel and vanadium. Solids-free asphaltene samples were characterized by several complementary analytical techniques to determine the relative abundance of different carbon types and to calculate their average three-dimensional molecular conformations. Even though the parent bitumens came from geographically diverse sources the corresponding asphaltene fractions had similar structures. Each sample comprised basic units, or ‘cores’, of condensed aromatic rings connected by bridges. The main differences relate to the number and complexity of the basic units.

Hydrogen is a key reagent in the petroleum and petrochemical industry. Thus, the intrinsic solubility of hydrogen in organic liquids of industrial interest is an important parameter for process design and process modeling. The existing hydrogen solubility data base for industrial fluids is limited and does not account for the potential impact of trace additives such as clay and catalyst fines, on the apparent solubility of hydrogen in these media. Such finely divided solids present large solid–liquid interfaces where hydrogen can sorb in competition with the liquid media leading to an inadvertent overestimation of the intrinsic hydrogen solubility. In this work, the effect of common solid additives on the apparent solubility of hydrogen in hydrocarbon liquids has been investigated. Hydrogen solubilities in hexadecane, tetralin, and light and heavy virgin gas oils were measured with and without the solid additives, including a commercial hydrotreating catalyst (CHC), used CHC, CHC support, alumina, silica and carbon black. The measurements were made under a wide range of conditions: with upper limits of 380°C and 12.0 MPa. These solids all sorb hydrogen but only silica, used hydrotreating catalyst and hydrotreating catalyst support sorb significant amounts of hydrogen in the presence of liquid hydrocarbons. These latter three materials, present in many industrial heavy oil samples raise the apparent solubility of hydrogen in these liquids. The presence of such solids is rarely reported even when present. Thus, two sets of hydrogen solubility in heavy oil data exist in the literature — data where hydrogen solubility is over stated due to the presence of such solids and data that are unaffected.

The use of supercritical pentane, under increasingly severe conditions of temperature and pressure, allows residual oils to be separated into fractions with progressively higher molecular weight without significant chemical degradation. Characterisation of these individual fractions provides a more complete picture of bitumen resid chemistry than average values determined for the whole sample. In the work described here, this approach has been applied to resid samples taken from the bitumen upgrading units at the Syncrude Canada Ltd. plant in Northern Alberta (Oil Gas J, 20 (1997) 66; Rev Process Chem Engng, 1 (1998) 41). A significant amount of each sample was non-extractable under even the most severe conditions. These end-cuts from virgin bitumen pitch (P-EC), hydrocracking product resid (HC-EC) and coking product resid (CK-EC) were compared to pentane insoluble asphaltenes (ASP) from a conventional coker feed bitumen. In addition, the P-EC sample was subjected to further fractionation based on its solubility in different blends of toluene and pentane. The P-EC sample comprises about 55%(w/w) highly aromatic heavy molecules, rich in heteroatoms and metals. Smaller molecules, with much lower aromaticity and polarity, represent the remaining 45%(w/w). Owing to a their high heteroatom and metals content, the heavier molecules in this material are considered to be major coke precursors under thermal cracking conditions. However, in hydrocracking the free radicals generated by the cleavage of carbon–carbon and sulphur–carbon bonds are suppressed by hydrogen capping. As a result, the “difficult to crack” aromatic “cores” of the heavier components remain toluene soluble. Although these components do not form coke under hydrocracking conditions, they may cause fast catalyst deactivation. In existing commercial processes the residue from hydrocracking is recycled to extinction in a coker. Because of its intractable nature, this heavy resid may not be conducive to the production of lighter liquid products. It is suggested that, prior to hydrocracking, the heaviest portion of bitumen pitch be removed to avoid these problems.

Supercritical fluid extraction, narrow-cut characterization of bitumen pitch, hydrocracker and once-through coker vacuum resids revealed the unexpected process chemistry of bitumen hydrocracking. Hydrocracking appears to prolong the coke formation process of the end-cut material of bitumen, by converting it to coke precursors. The conversion (or removal) mechanism for most key species (microcarbon residue (MCR), metals, N) in hydrocracking is by partitioning, which is similar to coking. Sulfur species that convert in hydrocracking are from the front-end of bitumen pitch; there is only a small sulfur reduction in the end-cut. Bitumen pitch and resid products have similar MCR distribution which is dependent on the “depth” of resid, not the conversion processes. Coke yield did not correlate with the MCR content of narrow-cut feed; coke yield was insignificant at the front-fractions and high at the end-cut. The sub-fractions of bitumen derived resid products have lower H/C ratios than those of bitumen pitch, but have the same MCR content. This can be explained by the pendant-core model, in which bitumen pitch and resid products have the same amount of aromatic cores (coke precursors). The inverse correlation of key species with H/C ratio is process dependent. The reaction products of end-cut (mainly asphaltenes) remained in resid product slate (524°C+ materials) in once-through coking and hydrocracking operations. The implications for the current commercial bitumen upgrading flowsheet are also discussed.

An indirect method for measuring gas solubility in liquid media such as heavy oil, bitumen, petroleum residue and low volatility model hydrocarbons is reported. The method is intended for use with an existing X-ray view cell apparatus. With this apparatus it is possible to verify the number of phases present and to ensure that the phases are well mixed. For example, vortices in the impeller region are readily observed using transmitted X-ray imaging, despite the opacity of heavy hydrocarbons to visible light. Gas solubility data is obtained by tracking the location of the liquid–vapour interface. The volume of the view cell, the number of moles of gas added to the cell and the mass of the liquid phase are known. Once the volume of the liquid is obtained, the dissolved gas fraction is computed by difference. The method is applicable over the range of conditions accessible with the view cell apparatus — from ambient conditions up to 450°C and 30 MPa. For sparingly soluble gases such as hydrogen, solubilities measured using this method fall within 5% of values reported in the literature for hexadecane and tetralin at pressures greater than 2 MPa. Measured values are repeatable to within 2%. Hydrogen solubilities in a light virgin gas oil, a heavy virgin gas oil, Athabasca bitumen vacuum bottoms and Gudao atmospheric residuum are reported over a broad range of temperatures (80–380°C) and pressures (0.5–12 MPa). The solubility values obtained for the four cuts differ significantly at low temperatures but fall within a narrow range at elevated temperatures where the values do not differ markedly from values obtained for much lighter fluids such as tetralin.

A mechanism for the hot water extraction process is proposed based on new results from extraction tests using model oil sand. It was found that bitumen can be completely liberated from the oil sand matrix and forms aerated droplets during slurrying with water without adding process aids. However, the aerated bitumen droplets were unable to float due to the attachment of sand particles on the surface of the bitumen droplets. When sodium hydroxide (NaOH) was added, the sand particles were released from the bitumen droplets, resulting in bitumen recovery. High recoveries were obtained by adding NaOH to either connate water or slurry water. Bitumen loss was attributed to incomplete bitumen/sand separation and oil-in-water (o/w) emulsification resulting from deficiency and overdose of NaOH, respectively. The use of commercial sodium naphthenate or sodium laurate as process aids had no effect. The size of the aerated bitumen droplets increased as the oil content and/or the size of the sand particles increased. The bitumen recovery and the size of the aerated bitumen droplets increased when the sand was pretreated with NaOH. Liberation of bitumen from the oil-wet model oil sand could be achieved by using excess NaOH, but the liberated bitumen was non-recoverable due to emulsification. Increasing the amount of slurry water had a detrimental effect on aeration.

Bitumen—sand interaction was studied as a function of pH, particle size, temperature and solvent addition to bitumen. Sand particles can be easily detached from the bitumen surface at pH > 6. At pH