Showing papers in "Energy & Fuels in 2010"
TL;DR: Asphaltenes, the most aromatic components of crude oil, are critical to all aspects of petroleum use, including production, transportation, refining, upgrading, and heavy-end use in paving and coating materials as mentioned in this paper.
Abstract: Asphaltenes, the most aromatic of the heaviest components of crude oil, are critical to all aspects of petroleum use, including production, transportation, refining, upgrading, and heavy-end use in paving and coating materials. As such, efficiency in these diverse disciplines mandates proper chemical accounting of structure−function relations of crude oils and asphaltenes, the vision of petroleomics (Asphaltenes, Heavy Oils and Petroleomics; Mullins, O. C., Sheu, E. Y., Hammami, A., Marshall, A. G., Eds.; Springer: New York, 2007). Indeed, the molecular characterization of asphaltenes is required as well as the detailed understanding of the hierarchical colloidal structures of asphaltenes and petroleum. With great prescience, Professor Teh Fu Yen and co-workers proposed a hierarchical model of asphaltenes to account for many of their characteristics known at that time (Dickie, J. P.; Yen, T. F. Macrostrucutres of asphaltic fractions by various instrumental methods. Anal. Chem. 1967, 39, 1847−1852). This m...
922 citations
TL;DR: This article converted the marine microalga Nannochloropsis sp. into a crude bio-oil product and a gaseous product via hydrothermal processing from 200 to 500 °C and a batch holding time of 60 min.
Abstract: We converted the marine microalga Nannochloropsis sp. into a crude bio-oil product and a gaseous product via hydrothermal processing from 200 to 500 °C and a batch holding time of 60 min. A moderate temperature of 350 °C led to the highest bio-oil yield of 43 wt %. We estimate the heating value of the bio-oil to be about 39 MJ kg−1, which is comparable to that of a petroleum crude oil. The H/C and O/C ratios for the bio-oil decreased from 1.73 and 0.12, respectively, for the 200 °C product to 1.04 and 0.05, respectively, for the 500 °C product. Major bio-oil constituents include phenol and its alkylated derivatives, heterocyclic N-containing compounds, long-chain fatty acids, alkanes and alkenes, and derivatives of phytol and cholesterol. CO2 was always the most abundant gas product. H2 was the second most abundant gas at all temperatures other than 500 °C, where its yield was surpassed by that of CH4. The activation energies for gas formation suggest the presence of gas-forming reactions other than steam...
691 citations
TL;DR: Results showed that, if the future target for the productivity of lipids from microalgae, such as C. vulgaris, of ∼40 tons ha−1 year−1 could be achieved, cultivation in typical raceways would be significantly more environmentally sustainable than in closed air-lift tubular bioreactors.
Abstract: Life-cycle assessment has been used to investigate the global warming potential (GWP) and fossil-energy requirement of a hypothetical operation in which biodiesel is produced from the freshwater alga Chlorella vulgaris, grown using flue gas from a gas-fired power station as the carbon source. Cultivation using a two-stage method was considered, whereby the cells were initially grown to a high concentration of biomass under nitrogen-sufficient conditions, before the supply of nitrogen was discontinued, whereupon the cells accumulated triacylglycerides. Cultivation in typical raceways and air-lift tubular bioreactors was investigated, as well as different methods of downstream processing. Results from this analysis showed that, if the future target for the productivity of lipids from microalgae, such as C. vulgaris, of ∼40 tons ha−1 year−1 could be achieved, cultivation in typical raceways would be significantly more environmentally sustainable than in closed air-lift tubular bioreactors. While biodiesel pr...
542 citations
TL;DR: In this paper, marine macroalgae Enteromorpha prolifera was converted to bio-oil by hydrothermal liquefaction in a batch reactor at temperatures of 220−320 °C.
Abstract: Marine macroalgae Enteromorpha prolifera, one of the main algae genera for green tide, was converted to bio-oil by hydrothermal liquefaction in a batch reactor at temperatures of 220−320 °C. The liquefaction products were separated into a dichloromethane-soluble fraction (bio-oil), water-soluble fraction, solid residue, and gaseous fraction. Effects of the temperature, reaction time, and Na2CO3 catalyst on the yields of liquefaction products were investigated. A moderate temperature of 300 °C with 5 wt % Na2CO3 and reaction time of 30 min led to the highest bio-oil yield of 23.0 wt %. The raw algae and liquefaction products were analyzed using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, gas chromatography−mass spectrometry (GC−MS), and 1H nuclear magnetic resonance (NMR). The higher heating values (HHVs) of bio-oils obtained at 300 °C were around 28−30 MJ/kg. The bio-oil was a complex mixture of ketones, aldehydes, phenols, alkenes, fatty acids, esters, aromatics, and nitrogen-cont...
503 citations
TL;DR: The most relevant conclusions obtained from the analysis of the literature, analyzing the state-of-the-art results, trying to infer the viability of Ionic liquids as an alternative to the available amine-based absorption processes, and showin... as mentioned in this paper.
Abstract: The capture of CO2 from flue gases derived from fossil-fueled power plants and the absorption of CO2/H2S for natural gas sweetening purposes are two relevant industrial problems closely related to very important environmental, economical, and technological problems that need to be solved. Amine-based technologies are widely used in the industry for these purposes, but they lead to several problems that have led many researchers to pose new alternatives. Ionic liquids (ILs) have emerged in the last few years as promising new acid gas absorbents, and thus, this remarkable interest, in both industry and academia, has led to a large collection of experimental and theoretical studies in which the most important aspects of the absorption process are analyzed. In this review, we show the most relevant conclusions obtained from the analysis of the literature, analyzing the state-of-the-art results, trying to infer the viability of ILs as an alternative to the available amine-based absorption processes, and showin...
473 citations
TL;DR: A review of the available literature data about the solubility of various carbohydrates in ionic liquids and their interactions with carbohydrates to assess the current state of knowledge.
Abstract: While carbohydrates serve as an abundant, diverse, and reusable source of carbon, their derivatization for industrial applications is still a challenging task because of the low solubility in solvents other than water. Ionic liquids are recognized as green solvents for carbohydrate processing. However, only a limited number of studies have been carried out to investigate their ability to dissolve and modify saccharides. Most of the works focus on cellulose. The aim of this Review is to assess the current state of knowledge regarding the solubility of carbohydrates in ionic liquids but not on modifications of carbohydrates in ionic liquids. We herein collect all of the available literature data about the solubility of various carbohydrates in ionic liquids and highlight their interactions with carbohydrates. The subject of functionalization of carbohydrates in ionic liquids is not discussed in this Review.
453 citations
TL;DR: In this paper, the authors examined torrefaction of rice husks and four other agriculture residues (sawdust, peanut husks, bagasse, and water hyacinth) in nitrogen.
Abstract: Torrefaction improves the thermochemical properties of biomass that are relevant to combustion, co-combustion with coal, or gasification. This study examines torrefaction of rice husks and four other agriculture residues (sawdust, peanut husks, bagasse, and water hyacinth) in nitrogen. Two main operating parameters of torrefaction, temperature and residence time for the process, were varied in the range of 250−300 °C and 1−2 h, respectively. Product evolution and mass and energy losses during torrefaction were measured. Similar to other work, the torrefied products in the present work were characterized by a more brownish color, reduced moisture content and volatile matter, and increased ash, fixed carbon content, and energy density. The difference between the mass and energy yield was shown to improve for the higher torrefaction temperatures investigated. For the biomass studied, the torrefied bagasse at 300 °C and 1.5 h resulted in the highest higher heating value (HHV) of 25.68 MJ/kg of product, which ...
370 citations
TL;DR: In this paper, a stepwise market introduction is proposed: bio-oil would first replace fuel oil in boilers, where its properties would not be suitable for use in conventional liquid fuels.
Abstract: Fast pyrolysis bio-oil (pyrolysis liquid) from plant residues is one alternative to replace fossil fuels and feedstocks. Fast pyrolysis liquid is a potential source of revenues for companies who have biomass residues at their disposal. Once produced, bio-oils may be shipped, stored, and utilized much like conventional liquid fuels once their specific fuel properties are taken into account. First encouraging large scale bio-oil utilization tests with published results were carried out in Stockholm in the 1990s in a heating boiler designed for heavy fuel oil. Industrial ovens are also potential users of bio-oil. Bio-oil would also be an interesting fuel for small scale distributed heat or power production. However, introducing a new fuel into the markets is not going to happen easily. Bio-oil is quite different from conventional liquid fuels, and many challenges remains to be overcome. A stepwise market introduction is proposed: bio-oil would first replace fuel oil in boilers, where its properties would not...
364 citations
TL;DR: In this article, the authors have shown that short-chain alcohols depict poor blending stability and low viscosity (mainly for concentrations of ethanol and propanol in diesel fuel blends beyond 22 and 45%, respectively).
Abstract: Alcohols have an interesting potential as blending components for diesel fuels because of their capacity to reduce soot formation. Because they have increasing routes for their production from renewable sources, they could contribute toward increasing the renewable fraction of these fuels and, therefore, toward reducing the impact of diesel transportation on the global warming effect. To increase the knowledge about the implications of the use of short- and long-chain alcohols/diesel fuel blends in diesel engines, the stability, lubricity, viscosity, and cold filter plugging point (CFPP) have been tested. Blends of methanol, ethanol, propanol, butanol, and pentanol with diesel fuel have been analyzed at 1, 2.5, 7.7, 17, 50, 75, and 90% in volume [including 95% (v/v) in the case of CFPP]. Results have shown that short-chain alcohols depict poor blending stability and low viscosity (mainly for concentrations of ethanol and propanol in diesel fuel blends beyond 22 and 45%, respectively). A synergistic effect...
339 citations
TL;DR: In this article, the surface nature of Y-type zeolite was changed after tetraethylenepentamine (TEPA) modification, which causes a significant enhancement in CO2 adsorption capacity.
Abstract: Commercially available Y-type zeolite with a Si/Al molar ratio of 60 (abbreviated as Y60) was modified by tetraethylenepentamine (TEPA) to study their characterizations and adsorption/desorption properties of CO2 from gas streams. The surface nature of Y60 was changed after TEPA modification, which causes a significant enhancement in CO2 adsorption capacity. The CO2 adsorption capacity of Y60(TEPA) increased with the temperature at 30−60 °C but decreased with the temperature at 60−70 °C. The mechanism of CO2 adsorption on Y60 is entirely a physical interaction but becomes mainly attributable to a chemical interaction after TEPA modification. The CO2 adsorption capacity of Y60(TEPA) was influenced by the presence of water vapor and reached as high as 4.27 mmol of CO2/g of sorbent at a water vapor of 7%. The cyclic CO2 adsorption showed that the adsorbed CO2 could be desorbed from the surface of Y60(TEPA) at 75 °C for 4 h. The adsorption capacities and the physicochemical properties of Y60(TEPA) were preser...
327 citations
TL;DR: Fathi et al. as discussed by the authors used smart water as a wettability modifier in carbonate reservoirs to improve the initial wetting condition and the alteration of the water's pH.
Abstract: "Reprinted (adapted) with permission from Fathi, S J., Austad, T., Strand S. (2010) “Smart water” as a wettability modifier in chalk: The effect of salinity and ionic composition. Energy & Fuels 24(4), pp. 2514–2519. Copyright 2010 American Chemical Society. The article forms part of Jafar Fathi's PhD thesis: Water-based enhanced oil recovery (EOR) in carbonate reservoirs : initial wetting condition and wettability alteration by "Smart Water", Stavanger : University of Stavanger
TL;DR: In this article, a Liaohe crude oil was separated as saturates, aromatics, resins, and asphaltenes (SARA) and neutral nitrogen fractions, and its subfractions were analyzed by negative-ion electrospra...
Abstract: A Liaohe crude oil was separated as saturates, aromatics, resins, and asphaltenes (SARA) and neutral nitrogen fractions. The crude oil and its subfractions were analyzed by negative-ion electrospra...
TL;DR: In this article, the behavior of ilmenite as an oxygen carrier in CLC and the changes in its properties through redox cycles were analyzed, where the main products of coal pyrolysis and gasification were used as reducing gases.
Abstract: Ilmenite, a natural mineral composed of FeTiO3, is a low-cost and promising oxygen carrier (OC) for solid fuels combustion in a chemical-looping combustion (CLC) system. The aim of this study is to analyze the behavior of ilmenite as an OC in CLC and the changes in its properties through redox cycles. Experiments consisting of reduction−oxidation cycles in a thermogravimetric analyzer were carried out using the main products of coal pyrolysis and gasification, that is, CH4, H2, and CO, as reducing gases. Characterizations of ilmenite through scanning electron microscopy−energy-dispersive X-ray (SEM−EDX), X-ray diffraction (XRD), Hg porosimetry, N2 fisisorption, He pycnometry, and hardness measures have been performed. Both fresh and previously calcined at 1223 K ilmenite have been used as initial OCs. Fresh ilmenite reacts slowly; nevertheless, there is a gain in reactivity in reduction as well as in oxidation with the number of cycles. This activation occurs for all tested fuel gases and is faster if ilm...
TL;DR: In this article, analytical expressions for characterizing a spontaneous co-current imbibition process of wetting fluid into gas-saturated porous media are proposed based on the fractal characters of porous media.
Abstract: Spontaneous capillary imbibition is an important fundamental phenomenon existing extensively in a variety of processes such as polymer composite manufacturing, oil recovery, soil science and hydrology, etc. In this work, analytical expressions for characterizing a spontaneous co-current imbibition process of wetting fluid into gas-saturated porous media are proposed based on the fractal characters of porous media. The mass of imbibed liquid is expressed as a function of the fractal dimensions for pores and for tortuous capillaries, the minimum and maximum hydraulic diameter of pores, and the ratio for minimum to maximum hydraulic diameters, porosity, and fluid properties, as well as the fluid−solid interaction. The imbibed weight predicted by the present model is in good agreement with the available experimental data.
TL;DR: In this paper, the temperature dependence of the pyrolysis products of two types of lignin (Alcell Lignin and Asian Lignins) was investigated using pyrolysgas chromatography−mass spectrometry (PyGC−MS) and about 50 compounds were identified and quantified for each type of ligningin over a temperature range of 400−800 °C.
Abstract: The temperature dependence of the pyrolysis products of two types of lignin (Alcell lignin and Asian lignin) was investigated using pyrolysis−gas chromatography−mass spectrometry (PyGC−MS). About 50 compounds were identified and quantified for each type of lignin over a temperature range of 400−800 °C. The maximum yield of phenolic compounds was obtained at 600 °C for both lignins, which was 17.2% for Alcell lignin and 15.5% for Asian lignin. Most of the phenolic compounds had an individual yield of less than 1%; however, for Alcell lignin, 5-hydroxyvanillin was the highest yield at 4.29 wt % on dry ash-free lignin, and for Asian lignin, 2-methoxy-4-vinylphenol was the highest yield at 4.15 wt % on dry ash-free lignin.
TL;DR: In this article, the 50 wt % co-solvent of either methanol−water or ethanol−water was found to be the most effective solvent for the liquefaction of eastern white pine sawdust.
Abstract: Alcohol (methanol or ethanol) and water showed synergistic effects on biomass direct liquefaction, and the 50 wt % co-solvent of either methanol−water or ethanol−water was found to be the most effective solvent for the liquefaction of eastern white pine sawdust. The 50 wt % aqueous alcohol at 300 °C for 15 min produced a bio-oil yield at approximately 65 wt % and a biomass conversion of >95%. At a temperature higher than 300 °C, conversion of bio-oil to char was significant by repolymerization. The Fourier transform infrared spectroscopy (FTIR) and gas chromatography−mass spectrometry (GC−MS) analyses of the obtained bio-oils confirmed the presence of primarily phenolic compounds and their derivatives (such as benzenes), followed by aldehyde, long-chain (and cyclic) ketone and alcohol, ester, organic acid, and ether compounds. Gel permeation chromatography (GPC) results suggested that hot-compressed ethanol as the liquefaction solvent favored lignin degradation into monomeric phenols. The X-ray diffractio...
TL;DR: In an effort to process wet algal biomass directly, eliminate organic solvent use during lipid extraction, and recover nutrients for reuse, a catalyst-free, two-step technique for algal biodiesel production is developed.
Abstract: In an effort to process wet algal biomass directly, eliminate organic solvent use during lipid extraction, and recover nutrients (e.g., N, P, and glycerol) for reuse, we developed a catalyst-free, two-step technique for algal biodiesel production. In the first step, wet algal biomass (ca. 80% moisture) reacts in subcritical water to hydrolyze intracellular lipids, conglomerate cells into an easily filterable solid that retains the lipids, and produce a sterile, nutrient-rich aqueous phase. In the second step, the wet fatty acid-rich solids undergo supercritical in situ transesterification (SC-IST/E) with ethanol to produce biodiesel in the form of fatty acid ethyl esters (FAEEs). Chlorella vulgaris grown sequentially under photo- and heterotrophic conditions served as the lipid-rich feedstock (53.3% lipids as FAEE). The feedstock and process solids were characterized for lipid components using highly automated microscale extraction and derivatization procedures and high-temperature gas chromatography. Hyd...
TL;DR: In this article, an ionic liquid that can reduce the energy losses by 16% compared to a commercial monoethanolamine process was used to extract CO2 from post-combustion flue gas.
Abstract: Carbon dioxide (CO2) capture using aqueous amine scrubbing is currently considered the most feasible option for separating CO2 from post-combustion flue gas. Using simple absorption and stripping configurations, monoethanolamine has been commercially demonstrated to effectively scrub CO2 from post-combustion flue gas. However, the current capital and operating costs are high and do not meet the target of the Department of Energy to remove 90% of CO2 from post-combustion flue gas with no more than a 35% increase in the cost of electricity. The evaluation of advanced absorbents, adsorbents, and membranes is under way to find the most energy-efficient CO2-capture technology. We have modeled an ionic liquid that can reduce the energy losses by 16% compared to a commercial monoethanolamine process. The choice of the ionic liquid, 1-butyl-3-methylimidazolium acetate, has not been optimized but was chosen based on chemical absorption behavior and the desire to understand performance. Engineering design estimates...
TL;DR: In this article, a new sort of nanofluid phase-change material (PCM) was developed by suspending a small amount of nanoparticles in melting paraffin, and the nanoparticles were selected to add to the meltin.
Abstract: A new sort of nanofluid phase-change material (PCM) is developed by suspending a small amount of nanoparticles in melting paraffin. Cu, Al, and C/Cu nanoparticles were selected to add to the meltin...
TL;DR: In this paper, experiments have been carried out on a single-cylinder gasoline direct-injection (GDI) research engine to study the performance of DMF benchmarked against gasoline and what is considered to be the current biofuel leader, ethanol.
Abstract: Biomass has the potential to become an important source of energy for future automotive fuels. Recent biological and chemical improvements to the conversion of biomass-derived carbohydrates have produced high yields of liquid 2,5-dimethylfuran (DMF). This discovery has made DMF a possible substitute for petroleum-based gasoline, because they share very similar physicochemical properties, which are superior to those of ethanol. In the present study, experiments have been carried out on a single-cylinder gasoline direct-injection (GDI) research engine to study the performance of DMF benchmarked against gasoline and what is considered to be the current biofuel leader, ethanol. Initial results are very promising for DMF as a new biofuel; not only is the combustion performance similar to commercial gasoline, but the regulated emissions are also comparable.
TL;DR: The use of the total acid number (TAN) method for measuring the acidity of biomass fast pyrolysis bio-oil was evaluated in this article, where the main difference between the methods is that ASTM D664 is specified for higher TAN values than ASTMD3339.
Abstract: The use of the total acid number (TAN) method for measuring the acidity of biomass fast pyrolysis bio-oil was evaluated. Suggestions for carrying out the analysis have been made. The TAN method by American Society for Testing and Materials (ASTM) D664 or D3339 can be used for measuring the acidity of fast pyrolysis bio-oils and their hydrotreating products. The main difference between the methods is that ASTM D664 is specified for higher TAN values than ASTM D3339. Special focus should be placed on the interpretation of the TAN curves because they differ significantly from those of mineral oils. The curve for bio-oils is so gentle that the automatic detection may not observe the end point properly, and derivatization should be used. The acidity of fast pyrolysis bio-oils is mainly derived (60−70%) from volatile acids. Other groups of compounds in fast pyrolysis bio-oils that influence acidity include phenolics, fatty and resin acids, and hydroxy acids.
TL;DR: In this paper, a sodium hydroxide pretreatment of the switchgrass feedstock was investigated to improve the enzymatic digestibility of switchgrass for the fermentable sugar production in hydrolysis.
Abstract: Lignocellulose-to-ethanol conversion is a promising technology to supplement corn-based ethanol production. However, the recalcitrant structure of lignocellulosic material is a major obstacle to the efficient conversion. To improve the enzymatic digestibility of switchgrass for the fermentable sugar production in hydrolysis, sodium hydroxide pretreatment of the biomass feedstock was investigated. At 121, 50, and 21 °C, raw switchgrass biomass at a solid/liquid ratio of 0.1 g/mL was pretreated, respectively, for 0.25−1, 1−48, and 1−96 h at different NaOH concentrations (0.5, 1.0, and 2.0%, w/v). Pretreatments were evaluated based on the yields of lignocellulose-derived sugars in the subsequent enzymatic hydrolysis. At the best pretreatment conditions (50 °C, 12 h, and 1.0% NaOH), the yield of total reducing sugars was 453.4 mg/g raw biomass, which was 3.78 times that of untreated biomass, and the glucan and xylan conversions reached 74.4 and 62.8%, respectively. Lignin reduction was closely related to the ...
TL;DR: In this article, the mass and energy balance in wet torrefaction were established for these conditions, and the uncertainty analysis also showed that the temperature slightly affected the heat of reaction.
Abstract: Solid handling of diverse lignocellulosic biomass feedstock is very challenging for thermochemical conversion to renewable fuels. Wet torrefaction is a pretreatment process to convert biomass to energy-dense solid fuel, with relatively uniform handling characteristics. The fuel value of the produced solid may be as much as 36% higher than that of the original biomass. In the process, biomass is reacted with hot compressed water at the temperature of 200−260 °C. The mass and energy balance in wet torrefaction were established for these conditions. Products include pretreated solid, precipitates (simple sugars and sugar derivatives), volatile acids, and gases (carbon dioxide). With increasing temperature, the mass of the solid decreases, the fuel value of the solid increases, and the quantity of gas increases. The heat of reaction for each temperature was estimated from an energy balance. The uncertainty analysis also showed that the temperature slightly affected the heat of reaction, which is very close to...
TL;DR: The Shenhu area is located in the Pearl River Mouth Basin, the northern continental slope of the South China Sea as mentioned in this paper, and gas hydrate samples were recovered during the scientific expedition.
Abstract: The Shenhu Area is located in the Pearl River Mouth Basin, the northern continental slope of the South China Sea. In 2007, gas hydrate samples were recovered during the scientific expedition conduc...
TL;DR: In this article, a detailed chemical kinetic mechanism has been developed to simulate these results and will be used to approximate similar fuels, and the use of both types of facilities allows a broad temperature envelope to be investigated and therefore encompasses the complete range applicable to gas turbines.
Abstract: Rapid compression machine (RCM) and shock-tube facilities have been employed to study the oxidation of natural gas blends at high pressure and intermediate to high temperatures. The use of both types of facilities allows a broad temperature envelope to be investigated and therefore encompasses the complete range applicable to gas turbines. A detailed chemical kinetic mechanism has been developed to simulate these results and will be used to approximate similar fuels. Mixtures of CH4/C2H6/C3H8/n-C4H10/n-C5H12 have been studied in the temperature range 630−1550 K, in the pressure range 8−30 bar, and at equivalence ratios of 0.5, 1.0, and 2.0 in “air”. For shock-tube experiments, the diluent gas was nitrogen, whereas in the RCM experiments the diluent gas composition ranged from pure nitrogen (at lower temperatures) to pure argon (at the highest temperatures). In addition, the combustion chamber in the RCM was fitted with a thermostat and heating tape to control and vary the initial temperature thereby varyi...
TL;DR: In this article, it has been reported that metal catalysts can accelerate the aquathermolysis and thereafter the uses of several catalysts on this reaction have been studied, such as mineral, water-soluble, oil soluble, and dispersed catalysts.
Abstract: The catalytic aquathermolysis becomes an important area for investigation to solve some of the problems during exploration of heavy crude oil. It has been reported in 1982 by Hyne et al. that metals can accelerate the aquathermolysis and thereafter the uses of several catalysts on this reaction have been studied. It is believed that superheated water passes heat to the hydrocarbon, and some asphaltene molecules are broken down by thermal heat to small molecules. Hence the viscosity as well as flow properties of heavy oil are improved. Moreover, the added heat provides driving force or pressure so that the viscous oils can flow easily and increases the oil production. When the catalyst is present on this reaction system, the viscosity is reduced very deeply. In general the catalysts employed for aquathermolysis are mineral, water-soluble, oil soluble, and dispersed catalyst. The viscosity reduction with these catalysts is in the order of mineral < water-soluble catalyst < oil-soluble catalyst < dispersed c...
TL;DR: The year 2008 has witnessed unprecedented fluctuations in the oil prices as mentioned in this paper and the supply of crude oil to the international market oscillated to follow suite according to the law of supply and demand.
Abstract: The year 2008 has witnessed unprecedented fluctuations in the oil prices. During the first three-quarters, the oil price abruptly increased to $140/bbl, a level that has never been reached before; then because of the global economic crisis, the price dramatically plunged to less than $50/bbl by the end of the year losing more than 64% of the maximum price in less than three months period. The supply of crude oil to the international market oscillated to follow suite according to the law of supply and demand. This behavior affected oil production in all exporting countries. Nonetheless, the demand for crude oil in some developing countries, such as China and India, has increased in the past few years because of the rapid growth in the transportation sector in addition to the absence of viable economic alternatives for fossil fuel. The rapid growth in fuel demand has forced the policy makers worldwide to include uninterrupted crude oil supply as a vital priority in their economic and strategic planning.Even...
TL;DR: In this paper, the authors showed that the volatilization of inherent alkali and alkaline earth metallic (AAEM) species is 10−20% during the pyrolysis of raw wood, bark, and leaf samples.
Abstract: Biochars were prepared from the pyrolysis of the wood, leaf, and bark components of mallee biomass in a fixed-bed reactor at 750 °C. The results show that the volatilization of inherent alkali and alkaline earth metallic (AAEM) species is 10−20% during the pyrolysis of raw wood, bark, and leaf samples. Acid treatment of the biochar samples was also carried out to prepare a set of acid-treated biochar samples. Although the majority of the inherent AAEM species were removed by acid-treatment, there are always some AAEM species that could not be removed for all biochars. Steam gasification experiments of both the raw and acid-treated biochar samples were carried out in a fixed-bed reactor at 750 °C and a steam concentration of 8.2 vol %. Data on the instantaneous syngas composition were obtained as a function of biochar conversion during steam gasification. Our data illustrated the importance of, in the study of steam gasification reaction mechanisms and kinetics of solid fuels such as biochars, optimizing t...
TL;DR: In this paper, a weighted sum of gray gases model (WSGGM) is derived, which is applicable to computational fluid dynamics (CFD) modeling of both air−fuel and oxy−fuel combustion.
Abstract: Radiation is the principal mode of heat transfer in furnaces. Models for gaseous radiative properties have been well-established for air combustion. However, there is uncertainty regarding their applicability to oxy−fuel conditions. In this paper, a new and complete set of weighted sum of gray gases model (WSGGM) is derived, which is applicable to computational fluid dynamics (CFD) modeling of both air−fuel and oxy−fuel combustion. First, a computer code is developed to evaluate the emissivity of any gas mixture at any condition using the exponential wide band model (EWBM), and the calculated results are validated in detail against data in the literature. Then, the validated code is used to generate emissivity databases for representative air- and oxy-firing conditions, for each of which a refined WSGGM with new parameters is derived. The practical way to implement the model to CFD simulations of combustion systems is given. Finally, as a demonstration, the new model is implemented to CFD modeling of two ...
TL;DR: In this article, the adsorption of asphaltenes from heavy oil model solutions onto colloidal nanoparticles of γ-Al2O3 is investigated, and the effects of the following variables on the amount of adsorbed have been investigated, namely, contact time, initial concentration of Asphtenes, temperature, heptane/toluene ratio (H/T), coexisting molecules, and water content.
Abstract: Asphaltene adsorption onto nanoparticles is an attractive subject for the heavy oil industry for two important reasons. First, nanoparticles would remove asphaltenes from the heavy oil rapidly and thus making the remaining fraction of oil transportable for conventional processing. Second, nanoparticles could be employed as catalysts for upgrading asphaltenes into light usable distillates. The first part has been investigated in this study, while the second part will be communicated shortly. In this study, the adsorption of asphaltenes from heavy oil model solutions onto colloidal nanoparticles of γ-Al2O3 is investigated. Batch adsorption experiments were carried out at different initial asphaltene concentrations and temperatures. The effects of the following variables on the amount of asphaltene adsorbed have been investigated, namely, contact time, initial concentration of asphaltenes, temperature, heptane/toluene ratio (H/T), coexisting molecules, and water content. Asphaltene adsorption kinetics and is...