Fuel (v.92, #1)
Bioethanol production from sugar beet molasses and thick juice using Saccharomyces cerevisiae immobilized on maize stem ground tissue
by Radojka Razmovski; Vesna Vučurović (pp. 1-8).
► Sugar beet molasses and thick juice as raw materials for bioethanol production. ► Saccharomyces cerevisiae is immobilized on maize stem ground tissue as new carrier. ► Using this new biocatalyst for fermentation, a superior system was realized. ► Bioethanol fermentation under normal and very high gravity conditions was studied. ► Thick juice was found to be economically favorable, compared to molasses.The potential of by-products and intermediate products of sugar beet processing as raw materials for bioethanol production in Vojvodina region has a big scope in view of the demand of ethanol as an alternative for fossil fuels. Also, from ecological point of view, use of agricultural waste as carriers for cells immobilization is justifiable. The biocatalyst prepared by immobilization of Saccharomyces cerevisiae on maize stem ground tissue was used for batch fermentation of sugar beet molasses and thick juice under normal and very high gravity (VHG) conditions. Cell immobilization was observed by electron microscopy. The carrier was effective for cell immobilization and provided strength and stability to the yeast cell mass and functioned as a fortification against toxins and inhibitors, enabling efficient ethanol fermentation, particularly in VHG conditions. Three different initial glucose concentrations were tested: 100, 150 and 300g/l. The maximum ethanol concentration of 83.20g/l for molasses and 132.39g/l for thick juice were achieved in VHG fermentation by immobilized cells, whereas the free yeast cells were unsuccessful in the same media. Taking into consideration significant process parameters sugar beet thick juice was found to be economically favorable, compared to molasses, particularly in the VHG fermentation process.
Keywords: Bioethanol; Molasses; Thick juice; Maize stem; Immobilized cells
MnO and TiO solid catalysts with low-grade feedstocks for biodiesel production
by Kevin Gombotz; Robert Parette; Greg Austic; Dheeban Kannan; Jack V. Matson (pp. 9-15).
► Biodiesel was made with manganese oxide (MnO) and titanium oxide (TiO) catalysts. ► MnO and TiO were robust for both transesterification and esterification. ► MnO and TiO handled low quality feedstocks with no pretreatment. ► Using a two-stage process, high quality biodiesel and glycerol were produced.Manganese (II) oxide (MnO) and titanium (II) oxide (TiO) solid catalysts were found to be robust catalysts for both the transesterification of triglycerides and esterification of free fatty acids. These metal oxides were shown to exhibit long life with little loss of activity. The ability to esterify free fatty acids (FFA) and handle high levels of water illustrates the potential of these catalysts to produce biodiesel from low quality feedstocks without the pretreatment operations required with the traditional process. Some soaps were produced in the presence of free fatty acids, but soaps were within tolerable levels and formed at concentrations that were orders of magnitude lower than the traditional process. This results in significant reductions in product washing. By utilizing a 2-stage process, high quality fuel (meeting ASTM specifications) and glycerol were produced.
Keywords: Biodiesel; Heterogeneous catalyst; Esterification; Transesterification; Free fatty acids (FFA)
The role of the methyl ester moiety in biodiesel combustion: A kinetic modeling comparison of methyl butanoate and n-butane
by Kuang C. Lin; Jason Y.W. Lai; Angela Violi (pp. 16-26).
► We compare the combustion chemistry of n-butane and the alkyl ester methyl butanoate. ► Oxidation pathways associated with the methyl ester moiety suppress NTC behavior. ► Fuel-bound oxygen results in early formation of oxygenated species. ► The methyl ester moiety also leads to reduction in soot precursor production.Growth of the biodiesel industry has motivated increased study of the combustion characteristics of its constituent molecules and building combustion modeling capability. Understanding how these characteristics differ between bio-derived and conventional diesel fuels can help in evaluating biodiesel performance. A kinetic modeling comparison of methyl butanoate and n-butane, its corresponding alkane, contrasted the combustion of methyl esters and normal alkanes, towards understanding the effect of the methyl ester moiety. Utilizing a combined n-heptane and methyl butanoate kinetic mechanism in shock tube simulations, the results predicted no region of negative temperature coefficient (NTC) behavior for methyl butanoate, compared to a well defined NTC region for n-butane. We observed that oxidation pathways associated with the methyl ester moiety inhibited NTC behavior, through increased production of hydroperoxy radicals (HO2) instead of hydroxyl radicals (OH). In addition, we compared the evolution of carbon monoxide, carbon dioxide, ethylene and acetylene. The early formation of CO and CO2, directly from methyl butanoate, revealed unique reaction pathways that also influenced a reduction in soot precursor formation. Overall, these results will help to understand how combustion processes change with the inclusion of oxygenated fuels, which will inform the study and design of combustion technologies.
Keywords: Methyl ester; Biodiesel combustion; Kinetic modeling; Combustion characteristics; Methyl butanoate
Identifying the role of fly ash properties for minimizing sulfate-heave in lime-stabilized soils
by M.J. McCarthy; L.J. Csetenyi; A. Sachdeva; R.K. Dhir (pp. 27-36).
► Three clays of varying sulfate level and seven fly ashes covering a range of properties tested in lime-stabilized mixes. ► Coarser compacted soil structure obtained with higher fly ash levels and coarse, high loss-on-ignition (LOI), wet-stored material. ► Sulfate-induced heave (swelling) reduced with higher fly ash levels and coarse, high LoI, wet-stored material. ► High sulfate levels in fly ash reduce effectiveness of material in minimizing heave. ► Suggested methodology given for fly ash selection to minimize sulfate-induced heave.The paper describes a study carried out to examine the effects of fly ash in limiting damaging sulfate-heave (swelling) in lime-stabilized soils. This considered three clays with various sulfate levels; seven fly ashes covering a range of physical and chemical properties, and stored under different conditions (dry, stockpiled and ponded); and a typical quicklime. The initial part of the study examined the effects of fly ash (applied at levels of 6 to 24% by mass of dry soil) on compaction (in terms of density/moisture relationships) of the lime-stabilized soils (using 3.0% lime) to establish mix compositions and provide an insight to their resulting structure. This indicated that maximum dry density (MDD) and optimum moisture content (OMC) were influenced by the characteristics of fly ash (reducing and increasing respectively with increasing fly ash coarseness and loss-on-ignition (LoI; including that under wet storage)) and, depending on these, by the level of application. Tests for sulfate-heave were made following the BS EN 13286-49 volumetric swelling method. Fly ash gave systematic reductions in sulfate-heave with increasing application level up to 24% for the lime-stabilized soils tested. It was found that coarse, high LoI fly ashes, stored under wet conditions, were most effective in limiting the process, suggesting that the coarser structure obtained during compaction with these materials, i.e. lower MDD, is an important factor influencing this. The presence of high sulfate levels in fly ash reduced the effectiveness of the material in this role. The practical implications are considered and a nomogram relating fly ash fineness and application level, MDD and sulfate-swelling is developed, which demonstrates a possible methodology for material selection with regard to minimizing damage.
Keywords: Clay soils; Lime-stabilization; Dry, stockpile and pond-stored fly ash; Moisture/density relationships; Minimizing sulfate-heave
Real-time and robust estimation of biodiesel blends
by Saleh Mirheidari; Matthew Franchek; Karolos Grigoriadis; Javad Mohammadpour; Yue-Yun Wang; Ibrahim Haskara (pp. 37-48).
► We use fault detection methods to estimate biodiesel blend in the fuel. ► Biodiesel has less energy content compared to diesel. ► NO x sensor, and UEGO sensor measurements are used for estimation. ► Sensitivity of methods to measurement errors are investigated.Biodiesel as a renewable alternative fuel produces lower exhaust emissions with the exception of nitrogen oxides (NO x) when compared to the conventional diesel fuel. Reducing nitrogen oxides produced from engines running on biodiesel requires proper engine controller adaptations that are linked to the specifics of the fuel blend. Therefore, online estimation of fuel blend is a critical step in allowing diesel engines to maintain performance while simultaneously meeting emission requirements when operating on biodiesel blends. Presented in this paper are three different model-based biodiesel blend estimation strategies using: (i) crankshaft torsionals, (ii) NO x emissions measurement from the exhaust stream, and (iii) oxygen content measurement of the exhaust stream using a wide-band UEGO sensor. Each approach is investigated in terms of the accuracy and robustness to sensor errors. A sensitivity analysis is conducted for each method to quantify robustness of the proposed fuel blend estimation methods.
Keywords: Fuel blend estimation; System Identification; Online adaptive model
Investigation of the effect of Cu addition on the SO2-resistance of a CeTi oxide catalyst for selective catalytic reduction of NO with NH3
by Xue-sen Du; Xiang Gao; Li-wen Cui; Yin-cheng Fu; Zhong-yang Luo; Ke-fa Cen (pp. 49-55).
Display Omitted► SO2 sulfation resulted in the reduction of Ce4+ to Ce3+ on the CeTi oxide catalyst. ► The Cu atoms in the CeCuTi oxide will preserve the adjacent Ce4+. ► The reducibility of the CeTi catalyst significantly decreased due to the sulfation. ► The reducibility of the CeCuTi catalyst maintained at a qualified level for SCR.A series of characterizations including TEM–EDS, XRD, FTIR, SO2+O2 TPD, XPS, H2-TPR and NH3-TPD has been carried out to explore the mechanism of the promoting effect of Cu addition on the SO2-resistance of the CeTi oxide catalyst. SO2 had been found to strongly interact with surface cerium oxygen and result in the reduction of Ce4+ to Ce3+ on the CeTi oxide catalyst. The Cu atoms in the CeCuTi oxide catalyst will preferentially interact with SO2 and preserve the adjacent Ce4+. The redox ability of the CeTi catalyst was found to significantly decrease due to the sulfation by SO2. Due to the formation of CuSO4 and the preserved Ce4+, the reducibility of the CeCuTi catalyst has not significantly decreased like the CeTi catalyst but slightly decreased to an adequate level for SCR reaction after sulfation. The surface acidities of CeTi and CeCuTi were both enhanced by sulfation. The preservation of the redox ability and the increase of surface acidity after sulfation had caused CeCuTi to be a high SO2-resistance catalyst for SCR reaction. A graphical description of the effect of the Cu addition on the SO2-resistance of a CeTi oxide catalyst has also been proposed.
Keywords: Selective catalytic reduction; Ceria oxide; Copper oxide; NH; 3; SO; 2; resistance
Rice husk ash as an adsorbent for purifying biodiesel from waste frying oil
by Márcia Cardoso Manique; Candice Schmitt Faccini; Bruna Onorevoli; Edilson Valmir Benvenutti; Elina Bastos Caramão (pp. 56-61).
Display Omitted► Rice husk uses as adsorbent material for biodiesel production. ► A new use of a agro industrial residue: rice husk. ► Biodiesel production from waste material.The goal of this work is to study the purification of biodiesel from waste frying oil (WFO) using rice husk ash (RHA) at concentrations of 1%, 2%, 3%, 4% and 5% (w/w) and compare it with two other different purification methods, the traditional acid solution (1% aqueous H3PO4) and with the commercial adsorbent Magnesol® 1% (w/w). The structure and composition of the RHA were studied to better understand its properties as an adsorbent. In a concentration of 4%, the RHA showed excellent results for removal impurities from biodiesel. The high concentration of silica in its composition and the presence of meso and macropores can explain its high capacity of adsorption. Thus, the RHA, that is a byproduct of the rice processing, can appear as an alternative material for biodiesel purification.
Keywords: Rice husk ash; Adsorbent; Biodiesel; Magnesol; Acid washing
1H low- and high-field NMR study of the effects of plasma treatment on the oil and water fractions in crude heavy oil
by Hercílio D.A. Honorato; Renzo C. Silva; Cleiton K. Piumbini; Carlos G. Zucolotto; André A. de Souza; Alfredo G. Cunha; Francisco G. Emmerich; Valdemar Lacerda Jr.; Eustáquio V.R. de Castro; Tito J. Bonagamba; Jair C.C. Freitas (pp. 62-68).
Display Omitted► Study of crude and plasma-treated heavy oils naturally containing emulsified water. ►1H low- and high-field NMR allowed detailed assessment of plasma treatment effects. ► Oil viscosity was reduced after plasma-treatments. ► Effects on water and oil portions were separately analyzed by NMR. ► Good correlation observed between viscosity and T2 of the oil fraction.The chemical and physical properties of a Brazilian heavy oil submitted to plasma treatment were investigated by1H low- and high-field nuclear magnetic resonance (NMR) combined to the characterization of rheological properties, thermogravimetry and measurement of basic sediments and water (BSW) content. The crude oil was treated in a dielectric barrier discharge plasma reactor, using natural gas, CO2 or H2 as working gas. The results indicated a large drop in the water content of the plasma-treated samples as compared to the crude oil, giving rise to a reduction in the viscosity. No significant chemical change was produced in the oil portion itself, as observed by1H NMR. The water contents determined by1H low-field NMR analyses agreed well with those obtained by BSW, indicating the low-field NMR methods as a useful tool for following the effects of plasma treatments on heavy oils, allowing the separation of the effects caused on the water and oil fractions.
Keywords: NMR; Heavy oil; Plasma; Relaxometry
Preparation and characterization of activated carbon from oil sands coke
by Christina C. Small; Zaher Hashisho; Ania C. Ulrich (pp. 69-76).
Activated carbon with favourable adsorption properties was prepared from oil sands delayed and fluid cokes.Display Omitted► Oil sand coke is a suitable precursor for activated carbon preparation. ► Increased temperature, steam rate and time promote surface area development. ► Activated oil sand coke can potentially be used in oil sand tailings treatment.Several million tonnes of oil sands coke are generated each year in Alberta, Canada as a by-product of bitumen upgrading. Due to its high carbon content, oil sands coke can be a suitable precursor for the preparation of activated carbon. In this study, delayed and fluid oil sands coke were physically activated in a muffle furnace under select conditions of activation time (2–6h), temperature (800–900°C), steam rate (0.3–0.5mL/min), and activation atmosphere (CO2, CO2+steam, and N2+steam). The activated products were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, nitrogen adsorption, iodine and methylene blue tests. An increase in activation time and temperature resulted in higher surface areas in both delayed and fluid coke due to an enhanced etching of pores. An increase in steam rate led to the production of the highest specific surface area (577m2/g) and iodine number (670mg/g) within delayed coke; whereas, a lower steam rate resulted in the production of the highest specific surface area (533m2/g) and iodine number (530mg/g) in activated fluid coke samples.
Keywords: Oil sands coke; Physical activation; Structural characterization; Activated carbon
In situ FT-IR study of thiophene adsorbed on the surface of sulfided Mo catalysts
by Dong Liu; Zhen Li; Qiao Sun; Xue Kong; Azhen Zhao; Zongxian Wang (pp. 77-83).
► The adsorption of thiophene on the surface of sulfided Mo catalysts was theoretically and experimentally investigated. ► In situ FTIR technique confirmed the weak chemical absorption of thiophene on the catalyst surface. ► Four complexes were formed through the coordination of S, CC and CC with unsaturated Mod+ sites. ► The larger binding energy suggests the favorable absorption is through the coordination of CC with unsaturated Mod+ sites.The hydrodesulfurization (HDS) of thiophene and its derivatives by Mo-based catalysts shows significant economic benefits in crude oil processing and refining. Several Mo-based catalysts have been successfully used for HDS reaction despite of unclear catalytic mechanism. Thereby we use in situ FT-IR technique to investigate the adsorption of thiophene on the surface of supported and dispersed sulfided Mo catalysts. The results demonstrate that thiophene can be adsorbed on the catalyst surface through coordination of S atom, CC and CC with the unsaturated Mod+ sites located on the edge planes of MoS2-like structures, forming four different complexes. These adsorption manners were also proved by theoretical calculation with the density functional method (DFT). The calculated binding energy of η2(S) complex is larger than other complexes, suggesting that thiophene preferred to being adsorbed on the catalyst surface through the coordination of CC with unsaturated Mod+ sites. The formation of coordinated complexes can decrease the aromaticity of thiophene ring and weaken CS bond, which could promote the HDS reaction.
Keywords: In situ FT-IR; Thiophene; Catalysis; Adsorption; HDS
Production of fermentable sugars from enzymatic hydrolysis of pretreated municipal solid waste after autoclave process
by Sujing Li; Xiaonan Zhang; John M. Andresen (pp. 84-88).
► An organic concentrate from MSW was employed to produce fermentable sugars. ► The optimum experimental condition of enzymatic hydrolysis of MSW was found. ► The maximum sugar yield and hydrolysis rate were found. ► The effect of time, particle size and substrate concentration was investigated.A ligno-cellulosic concentrate from municipal solid waste (MSW) obtained after an autoclave separation process was investigated for its potential as a feedstock to produce fermentable sugars for ethanol production. A maximum enzymatic hydrolysis conversion of 53% of the cellulose and hemi-cellulose was found using a particle size range of 150–300μm hydrolyzed in a 100ml buffer solution containing 6wt% lingo-cellulosic MSW concentrate with 90mg cellulase at pH 4.8 held at 40°C for 12h. The hydrolysis rate leveled off at longer hydrolysis time and with increased substrate concentration and was related to enzymatic access to substrate. Lower hydrolysis rate at smaller particle size indicates that the grinding process may change the surface chemistry or morphology of the fibers making them less available for enzyme access. A drop in the hydrolysis rate was observed for the particles above 300μm associate with the longer diffusion time for the enzyme into the fiber particles. The findings indicate that 152L of ethanol could be obtained from a ton of lingo-cellulosic concentrate from MSW.
Keywords: Ligno-cellulosic MSW concentrates; Autoclave process; Enzymatic hydrolysis
Enzymatic production of biodiesel from Pistacia chinensis bge seed oil using immobilized lipase
by Xun Li; Xiao-Yun He; Zhi-Lin Li; You-Dong Wang; Chun-Yu Wang; Hao Shi; Fei Wang (pp. 89-93).
► The non-edible PCO grows in harsh conditions and can produce a biodiesel. ► The PCO could offer an oil resource with reduced costs of raw materials. ► MI-ROL gave a higher biodiesel yield than AI-ROL in the first cycle. ► AI-ROL was more stable than MI-ROL in the transesterification of PCO.Biodiesel fuel from renewable non-edible woody plant oils has recently attracted more attention due to its environmental benefits and the reduced costs of raw materials. This study investigated the enzymatic transesterification of Pistacia chinensis bge seed oil (PCO) with methanol. The recombinant Rhizopus oryzae lipases (ROL) immobilized on macroporous resin and anion exchange resin, named as MI-ROL and AI-ROL, respectively, were used as biocatalysts. The transesterification reaction catalyzed by the immobilized lipase was investigated in a solvent-free system. The highest biodiesel yields of 92% and 94% were achieved under the optimum conditions (enzyme dosage 25IUAI-ROL/g PCO or 7IUMI-ROL/g PCO, methanol to oil molar ratio 5:1, water content 20% by weight of oil, temperature 37°C, and reaction time 60h). There was no obvious loss in the yield of biodiesel after being consecutively used for five cycles in the transesterification reactions using AI-ROL, while the yield of biodiesel remained above 60% after the MI-ROL was repeatedly used for four cycles.
Keywords: Pistacia chinensis bge; Rhizopus oryzae; Biodiesel; Resin; Transesterification
Simulations and process analysis of the carbonation–calcination reaction process with intermediate hydration
by William Wang; Shwetha Ramkumar; Danny Wong; Liang-Shih Fan (pp. 94-106).
► The CCR Process for CO2 and SO2 removal is modeled and analyzed. ► Internal process parameters and its effect on the CCR Process are examined. ► Net plant efficiency decreases 20–22% when placed in a subcritical power plant. ► The CCR Process uses less O2 than oxycombustion and less steam than amine scrubbing. ► The CCR Process can increase, maintain, or decrease net electrical output.Several technologies are currently being developed to separate carbon dioxide from large point sources, such as coal-fired power plants. An emerging technology that shows great potential is a calcium oxide–calcium carbonate cycle. A major drawback is the calcium carbonate decreases in reactivity over multiple cycles. The Ohio State University demonstrated in 2008 the first carbonation–calcination reaction (CCR) process that includes intermediate hydration for sorbent regeneration and its feasibility over multiple cycles at the 120kWth scale with actual flue gas from coal combustion. The CCR Process utilizes a calcium-based sorbent to react with the carbon dioxide and sulfur dioxide in a flue gas stream to form calcium carbonate and calcium sulfate, respectively. The carbon dioxide is subsequently released from the calcium carbonate to produce a high-purity, sequestration-ready carbon dioxide stream while regenerating the calcium oxide sorbent. The sulfur dioxide is fixated as calcium sulfate and removed through a purge stream. An intermediate hydration step restores reactivity to the calcium oxide sorbent. Process analysis from computer simulations shows the CCR Process to be highly effective and efficient in removing both carbon dioxide and sulfur dioxide at low energy penalties under realistic conditions. A 20–22% decrease in electricity generation efficiency with the CCR Process is expected, compared with amine scrubbing around 27% and oxy-combustion around 25% energy penalty. A 25–28% increase in thermal energy with the CCR Process is expected to maintain a constant electrical output. Further, the CCR Process consumes half the oxygen necessary for an oxy-combustion plant and 25% less steam necessary for amine scrubbing.
Keywords: Coal combustion; CO; 2; capture; Sulfur capture; Calcium sorbent; CCR
Effects of steam on the sulfation of limestone and NOx formation in an air- and oxy-fired pilot-scale circulating fluidized bed combustor
by Michael C. Stewart; Robert T. Symonds; Vasilije Manovic; Arturo Macchi; Edward J. Anthony (pp. 107-115).
► Sulfation under oxy-fuel combustion is explored at bench and pilot scales. ► In the presence of steam, direct sulfation is slower than indirect sulfation. ► Calcium utilization for air-firing can be increased by steam injection. ► Steam decreases NOx emissions for both air- and oxy-firing modes. ► Steam should be considered in future bench- and pilot-scale combustion studies.The existing fluidized bed combustion literature on sulfation shows that above 30% conversion, direct sulfation via reaction with CaCO3 is faster than indirect sulfation with CaO. However, while this is true for dry flue gases, it is not the case if steam (H2O(g)) is present at realistic levels for coal combustion, and it has been confirmed by experiments employing thermogravimetric analysis (TGA) and tube furnace (TF) testing that direct sulfation is in fact slower than indirect sulfation for nearly all levels of conversion if steam (H2O(g)) is present. In this work we have also examined the effects of H2O(g) on SO2 capture and NH3 oxidation to NOx over calcium-containing compounds under air- and oxy-fired conditions in a pilot-scale circulating fluidized bed combustor (CFBC) utilizing limestone addition. The results of the pilot-scale tests confirm suggestions from our previous work that sulfur capture from the air firing of low-moisture fuels benefits from steam-sulfation. For petroleum coke, the addition of 8%vol H2O(g) resulted in increased SO2 retention and Ca utilization, as well as decreased NOx emissions by up to 44%. The simultaneous reduction of SO2 and NOx was attributed to enhanced solid-state diffusion (sintering) by H2O(g). Under oxy-fuel-firing conditions, H2O(g) addition also resulted in decreased NOx emissions, but the pilot-scale tests showed poorer sulfur capture performance and calcium utilization as compared to air firing when H2O(g) was present, thereby reconfirming the TGA/TF results. It appears that most bench-scale work on sulfation to date has underestimated the true rate of reaction for sulfation in the presence of H2O(g). This conclusion explains at least in part why indirect sulfation is often faster than direct sulfation in pilot plant studies on oxy-fuel circulating fluidized bed combustion. Moreover, this work stresses the importance of including H2O(g) in bench-scale experiments that attempt to simulate real combustion environments.
Keywords: Oxy-fuel CFBC; Sulfation; SO; x; and NO; x; emissions; Steam
Evaluation of a laboratory rod mill when grinding bituminous coal
by Hoon Lee; Mark S. Klima; Paul Saylor (pp. 116-121).
► Population balance model was applied to rod mill grinding of coal. ► Back-calculated breakage parameters agreed with the experimental values. ► Simulated locked-cycle test results agreed with the experimental values.Laboratory testing was conducted to evaluate the breakage of bituminous coal in a rod mill. A Pittsburgh seam coal, which had been obtained from the product stream of an operating coal cleaning facility, was used as the feed material. This material had an ash value of 6.7% and had been crushed to a nominal −6.35mm. Grinding tests were carried out on a mono-size (2.38×1.68mm) fraction. The tests were conducted using a 193.5mm diameter and 245.0mm long laboratory rod mill, which contained steel rods at a volume loading of 23%. The mill was operated at 70% of critical speed for various grind times. A locked-cycle test was also performed to simulate continuous grinding conditions.The grinding was characterized using the population (or size–mass) balance model. The breakage distribution and rates of breakage were determined from the grinding data. The results indicated first-order breakage. The locked-cycle results indicated that steady state was achieved in several iterations. The simulated results matched the experimental results very well.
Keywords: Size–mass balance; Breakage rates; Breakage distribution; Gasifier feed
Product distributions including hydrocarbon and oxygenates of Fischer–Tropsch synthesis over mesoporous MnO2-supported Fe catalyst
by Xuejun Zhang; Yong Liu; Guiqing Liu; Kai Tao; Quan Jin; Fanzhi Meng; Ding Wang; Noritatsu Tsubaki (pp. 122-129).
Display Omitted► The FTS on mesoporous MnO2 supported Fe-based catalyst was investigated. ► A new product distribution was observed. ► Deviation of C2 hydrocarbon was due to the high productivity of C2 oxygenates.Catalytic reaction performances of home-made mesoporous MnO2-supported Fe-based catalyst with copper promoter for Fischer–Tropsch synthesis (FTS) are investigated in a slurry-phase reactor at 533K–573K and 1.0MPa. The present catalyst system exhibits high olefin selectivity, however, the selectivity to ethylene is lower than the extrapolation based on theC3+. Simultaneously, the catalyst gives high oxygenates productivity except for the C1 oxygenates. Comprehensive product distributions including hydrocarbon and oxygenates at different temperatures are presented. Particular attention is paid to the new overall distribution of product based on the carbon numbers when the hydrocarbon is combined with oxygenates. The new distributions at different temperatures show similar trends, displaying low C1 product selectivity and almost accordant C2 product selectivity with the extrapolation from Anderson–Schulz–Flory (ASF) law. An attempt is made to elucidate the deviation behavior of C1 and C2 hydrocarbon.
Keywords: Fischer–Tropsch synthesis; ASF distribution; Mesoporous MnO; 2; -support; Fe catalyst
Production and utilization performance of a glycerol derived additive for diesel engines
by Diana Hernández; Jhon J. Fernández; Fanor Mondragón; Diana López (pp. 130-136).
► Oxygenated compounds from catalytic glycerol decomposition have known energetic use. ► Glycerol derived additive decreases significantly the amount of particulate matter. ► The additive decreases the pour point of diesel by improving cold flow properties.Oxygenated additives have been the subject of much research because they notably improve the fuel characteristics and combustion performance. Moreover, there is a tendency to use oxygenated additives derived from biomass. In the case of glycerol, previous studies have shown that oxygenated compounds are generated by dehydration, decomposition and isomerization reactions from glycerol and its intermediaries, where the selected route of these reactions depends on the type of catalyst used.In this work, the liquid phase obtained during the catalytic glycerol decomposition at 400°C using a basic catalyst was characterized by GC and GC–MS. This phase is constituted mostly by highly oxygenated compounds of known energetic use. After a drying process, the effect of the glycerol condensates as an additive in diesel–biodiesel (B5) engines at the 0.2% (v/v) concentration was evaluated. The physical properties of the fuel and the mechanic, thermodynamic, and environmental performance of the stationary diesel engine were analyzed in the current study. The presence of the additive decreased the pour point of diesel and the amount of particulate matter generated during combustion.
Keywords: Glycerol; Catalysis; Decomposition; Emissions; Combustion
Air and oxy-fuel combustion behaviour of petcoke/lignite blends
by Nur Sena Yuzbasi; Nevin Selçuk (pp. 137-144).
► Air and oxyfuel combustion of lignite, petcoke and their blend was investigated. ► Under oxy-fuel conditions combustion is delayed. ► In oxygen enriched conditions, DTG curves shift to lower temperatures. ► Effect of oxygen concentration is more significant than that of diluting gas. ► Synergy is observed between the parent fuels during combustion of blend.The pyrolysis and combustion behaviour of a petroleum coke (petcoke), an indigenous lignite and their 70/30wt.% blend in air and oxy-fuel conditions were investigated by using non-isothermal thermo-gravimetric method (TGA) coupled with Fourier transform infrared (FTIR) spectrometer. Blend samples were prepared by mixing lignite, which has low calorific value, high ash and moisture contents with petcoke that has high calorific value, low ash and moisture content, in the proportion of 70:30. Pyrolysis tests were carried out in nitrogen and carbon dioxide environments which are the main diluting gases of air and oxy-fuel environments, respectively. Pyrolysis curves of parent fuels and their blend reveal close resemblance up to 700°C in both N2 and CO2 environments. At higher temperatures, further weight loss taking place in N2 and CO2 atmospheres is attributed to calcite decomposition and CO2-char gasification reaction, respectively. Gasification reaction leads to significant increase in CO and COS formation as observed in FTIR evolution profiles. Almost identical experimental and theoretical pyrolysis profiles of the blend samples show that there is no synergy between the parent fuels of the blend in both pyrolysis environments. Combustion experiments were carried out in four different atmospheres; air, oxygen-enriched air environment (30% O2–70% N2), oxy-fuel environment (21% O2–79% CO2) and oxygen-enriched oxy-fuel environment (30% O2–70% CO2). Combustion experiments show that replacing nitrogen in the gas mixture by the same concentration of CO2 leads to delay in combustion (lower maximum rate of weight loss and higher burnout temperatures). Overall comparison of derivative thermogravimetry (DTG) profiles shows that effect of oxygen content on combustion characteristics is more significant than that of diluting gas in the combustion environment. At elevated oxygen levels, profiles shift through lower temperature zone, peak and burnout temperatures decrease, weight loss rate increases significantly and complete combustion is achieved at lower temperatures and shorter times. Theoretical and experimental combustion profiles of the blend mainly display different trends, which indicate synergistic interactions between lignite and petcoke during their combustion in different environments.
Keywords: Petcoke lignite blend; Oxy-fuel combustion; TGA-FTIR
Partitioning of trace inorganic elements in a coal-fired power plant equipped with a wet Flue Gas Desulphurisation system
by Patricia Córdoba; Raquel Ochoa-Gonzalez; Oriol Font; Maria Izquierdo; Xavier Querol; Carlos Leiva; Maria Antonia López-Antón; Mercedes Díaz-Somoano; M. Rosa Martinez-Tarazona; Constantino Fernandez; Alfredo Tomás (pp. 145-157).
► Abatement capacity of trace inorganic elements was studied in a Coal-fired power plant. ► Most elements are retained efficiently as fly ash (ESP, 99.6%) and slag (11%). ► FGD attains high gaseous retention (92–100%) for S, Cl, F, Se, As, B, and Hg (67%). ► Gaseous emissions are below the limits according to 2001/80/EC and PRTR threshold. ► Gaseous Hg and particulate Se, As, Zn, Cu, Ni, and Cr are the proportion emitted.The abatement capacity of trace inorganic elements was studied in a large Pulverized Coal Combustion (PCC) power plant equipped with a wet limestone Flue Gas Desulphurisation (FGD) system. High proportions of most elements were retained as fly ash as consequence of the efficiency of the electrostatic precipitator (ESP, 99.6% of fly ash) and slag (11%). The most volatile elements, such as S and F are retained by the FGD gypsum, and Cl by the filtered water; whereas the moderately volatile elements, As and B, are retained mainly by fly ash, reaching very high abatement efficiencies for these elements when considering the whole plant (>92%). Selenium and Hg are still retained by the whole system with relatively high proportions (89% and 67%); however a prominently proportion is emitted; Se (11%) and Hg (29%), attaining gaseous/PM rate at the emissions reaching 0.08 and 290, respectively. The gaseous emissions are below the limits according to the European directive 2001/80/EC for large combustion plants and the PRTR threshold values with the exception of Hg emissions and particulate Se, As, Zn, Cu, Ni, and Cr. Remediation actions to prevent and/or reduce the gaseous and PM emissions as well as the determination of leachable potential of trace inorganic pollutants retained in FGD gypsum, especially F in view of its disposal, are of significant relevance.
Keywords: Trace inorganic elements; PCC; FGD; ESP; PRTR threshold
Measurements of normal boiling points of fatty acid ethyl esters and triacylglycerols by thermogravimetric analysis
by Carlos M. García Santander; Sandra M. Gómez Rueda; Nívea de Lima da Silva; Celso L. de Camargo; Theo G. Kieckbusch; M. Regina Wolf Maciel (pp. 158-161).
► The biodiesel simulation studies require reliable normal boiling point (NBP) data. ► Results show that calculated normal boiling points using Gani method are acceptable in the ethyl esters case. ► The ethyl ricinoleate NBP is not available in the Aspen plus V7 compounds data base. ► The ethyl ricinoleate NBP is not available in the open literature, here we reported this value. ► Our data allow more accurate characterization of biodiesel representative compounds.At present, a large number of studies of biodiesel production process using simulation packages are being developed. In these studies, vegetable oils and biodiesels are characterized in the software through representative compounds because of they are not in the compounds database of commercial simulators. With the aim to achieve a successfully characterization in these kinds of software, some properties of the substances must be available. The normal boiling point (NBP) is the most important property due to the fact that this property along with group contribution methods allows other properties calculation such as, e.g., critical properties and temperature dependency properties. In this work, a thermogravimetric analysis (TGA) method for rapid measurement of normal boiling points of two triacylglycerols and four ethyl esters, i.e., triolein, tripalmitin, ethyl oleate, ethyl palmitate, ethyl linoleate and ethyl ricinoleate, was used. Nowadays, in the open literature exists few data available about ethyl esters properties; hence, the results obtained here will contribute in the proposal, analysis, and evaluation of ethyl esters (biodiesel) virtual plants using reliable simulation packages. In addition, a more accurate characterization of compounds and therefore more accurate simulation results can be obtained when they are used.
Keywords: Triacylglycerols; Normal boiling point; Simulation package; Process simulation; Aspen plus; Ethyl esters
Modeling the slag layer in solid fuel gasification and combustion – Formulation and sensitivity analysis
by Sze Zheng Yong; Marco Gazzino; Ahmed Ghoniem (pp. 162-170).
► In this study we model the multiphase slag layer in a reactor. ► The model considers slag flow and heat characteristics, and particle capture. ► The model predicts the slag thickness, velocity, the temperature distribution. ► The model is tested with inputs from a CFD simulation of a pilot-scale combustor. ► Particle momentum transfer, particle capture, and slag properties are important.A steady-state model has been developed to describe the flow and heat transfer characteristics of the slag layer in solid fuel gasification and combustion. The model incorporates a number of sub-models including one for particle capture, and takes into consideration the temperature and composition dependent properties of slag, the contribution of momentum of captured particles and the possibility of slag resolidification. An equally important issue is the interaction of the particles colliding with the slag layer. High inertia particles tend to rebound whereas slower particles are trapped in the slag layer. Since only trapped particles are relevant to the slag layer build-up, a particle capture criterion for colliding particles is introduced. The model predicts the local thickness of the molten and the solid slag layers, the average slag velocity, the temperature distribution across the layer and the heat flux to the coolant, taking into account the influence of molten and resolidified slag layers coating the combustor or reactor wall.
Keywords: Slag model; Coal; Particle capture
Droplet vaporization modeling of rapeseed and sunflower methyl esters
by Sumer Dirbude; Vinayak Eswaran; Abhijit Kushari (pp. 171-179).
► Modeled single droplet evaporation for two biofuels. ► Effects of convection have been modeled using an effective Reynolds number. ► Studied the evaporation rate and temporal evolution of droplet diameter. ► A good match with the experiments and theory for two convection correlations. ► The oxidation follows the d2-law and is similar to a single component fuel.For numerical simulations of the combustion of liquid fuels, a thoroughly validated and verified quantitative model for droplet evaporation is necessary. In this work a simple single droplet infinite conductivity model is simulated for low pressure (0.1MPa) and various temperatures (550–1050K) using a chosen property rule (see Eq. ) and five convection correlations (C1, C2, C3, C4, and C5, see () to obtain the temporal evolution of droplet diameter squared, droplet surface temperature and average evaporation rates of vegetable oil derived biofuels – rapeseed methyl ester (RME) and sunflower methyl ester (SME) – under near-quiescent conditions. The predictions are compared with the experimental and analytical results of Morin et al. . The model uses an effective Reynolds number to conflate the effects of forced and natural convection. It is observed that the predicted temporal history of droplet diameter for RME droplet matches more closely with correlation C1 for Tamb⩽748K and correlation C2 for Tamb⩾803K at various ambient temperatures (i.e., from low to high evaporation rate). The correct droplet lifetime is predicted best by C1 for all temperatures. For average evaporation rates for SME, C1 best fits the experimental data. For the average evaporation rate of RME, the present model with C1 gives a better prediction than the theoretical, and corrected theoretical results of Morin et al. , and is observed to match closely with their experimental results. The present results using C2 are also found close to the experimental results for RME and SME. It is observed that the oxidation of RME/SME is similar to n-decane – a pure component fuel.
Keywords: Droplet evaporation modeling; Spray combustion; Convection correlations; Evaporation constant; Quasi-steady theory
Rapid quantitative determination by13C NMR of the composition of acetylglycerol mixtures as byproduct in biodiesel synthesis
by Abraham Casas; María Jesús Ramos; Ángel Pérez; Adolfo Simón; Covadonga Lucas-Torres; Andrés Moreno (pp. 180-186).
► Commercial mono- and diacetin are mixtures of partly acetylated glycerols. ►1H NMR spectra presents signal overlapping for these components. ► By31P NMR spectroscopy triacetin may not be identified and quantified. ►13C NMR allows the quantification of all the components in commercial mixtures. ►13C NMR results were validated with GC and HPLC-ELSD.Commercially available partly acetylated glycerols (mono- and diacetin) are mixtures of glycerol, 1- and 2-acetylglycerol, 1,2- and 1,3-diacetylglycerol, and triacetin. Diacetin and monoacetin are by-products of the biodiesel and triacetin production using glycerol esterification with acetic acid or triglyceride interesterification with methyl acetate. Usually, primary analytical methods involve chromatography (HPLC or GC), spectroscopy (MS or NIR), and wet chemical techniques (potentiometric, iodometric titration) which are often time-consuming due to sample preparation, extended analysis time and/or complicated data analysis. Moreover, these methods require pure mono- and diacetin as standard, which are commercially unavailable.In this work, a complete31P and13C chemical shift data for glycerol, mono-, di- and triacetin (including isomers) allows for the identification and quantification of these components in the commercial mixtures. This experimental protocol allows for rapid analysis of mixtures that include these six components. Quantitative31P NMR and13C NMR results were validated to those obtained with other analytical methods, such as GC and HPLC-ELSD.13C NMR is preferred due to allows to measure the content of triacetin, which has no free hydroxyl group, and no signal was detected by31P NMR.
Keywords: Biodiesel; Diacetin: monoacetin; 13; C NMR; GC; HPLC-ELSD
The effect of moisture on the sorption process of CO2 on coal
by Martina Švábová; Zuzana Weishauptová; Oldřich Přibyl (pp. 187-196).
► We studied moisture effect on CO2 sorption on coal samples at different temperatures. ► Moisture reduces sorption capacity and influences the heat of sorption. ► Change of heat of sorption is connected with change in pore size distribution. ► Sorption rates of all samples and temperatures decrease with pressure. ► Sorption rates of two samples decrease with moisture, for last one rate increases.The effect of moisture on both the sorption capacity and the kinetics of CO2 sorption was investigated on three coal samples originating from the Czech Republic. One sample was Darkov bituminous coal from the Czech part of the Upper Silesian Basin, while the two other samples were enriched maceral fractions of vitrinite (Fučík coal, Upper Silesian Basin) and huminite (Bílina coal, North Bohemian Basin), which differ in the degree of coalification and petrographic composition. Sorption measurements were performed up to pressures of 8bar and 1bar at Darkov coal and temperatures of 45°C (moisturized coal) and 55°C (dry coal). The modified Dubinin–Radushkevich equation was used to fit the sorption isotherm data, and the kinetic data was fitted by the linear driving force model. In all cases, the moisturized coal showed lower sorption capacity than the dry coal and the reduction in sorption capacity decreases with the increasing of carbon content. For the Darkov sample, the heat of sorption decreases with moisture, which is attributable to preferential attraction of water to high-energy sorption sites. Both moisturized enriched maceral fractions showed an increase in heat of sorption induced by the shift of the modus of radii towards smaller values.The sorption rates of all samples decreased with increasing pressure. It is assumed that the reason for this behavior is especially intensive gas-molecule collision. Both enriched maceral fractions showed a reduction in the sorption rates on the moisturized samples. This finding is in agreement with previously published results and is attributed to accumulation of water in the coal structure, with a resulting reduction in the pore radii and gas diffusion rates. The Darkov sample showed different behavior with an increase in the sorption rates of the moisturized samples. This behavior is connected with the fact that higher energy polar sites are preferentially occupied by water and are therefore not available for the uptake of CO2.
Keywords: CO; 2; Sorption; Moisture; Coal; Kinetics
Transesterification double step process modification for ethyl ester biodiesel production from vegetable and waste oils
by Rafael Guzatto; Diego Defferrari; Quelen Bülow Reiznautt; Ígor Renz Cadore; Dimitrios Samios (pp. 197-203).
► Biodiesel production using ethanol and different oils. ► TDSP methodology optimization for ethanolysis. ► High conversions and yields. ► High quality and purity biodiesel ethyl esters.In this study, the transesterification double step process (TDSP) was modified to enable the usage of ethanol as a transesterification agent in the production of biodiesel from vegetable and waste oils. The TDSP comprises a two-step transesterification procedure, which is initiated by a homogeneous basic catalysis step and followed by an acidic catalysis step. To optimize the transesterification parameters, different reaction mixtures and conditions were tested. Compared with methanol transesterification, larger ethanol and catalyst amounts as well as higher reaction times and temperatures were required. However, the results were consistent with those usually reported for ethanol transesterification. The obtained biodiesels (i.e., fatty acid ethyl esters (FAEEs)) were analyzed by standard physico-chemical techniques in addition to1H NMR,13C NMR and FTIR spectroscopies, indicating high quality and purity biodiesel products. The obtained conversions were evaluated by1H NMR spectroscopy. For the optimized process, the triglyceride conversion to biodiesel was ⩾97% for all oils used. The overall process yields are considerably high when compared to the single basic catalysis yields.
Keywords: TDSP; Acidic catalysis; Basic catalysis; Ethanolysis
Adsorption kinetics and equilibrium of copper from ethanol fuel on silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine polymers
by Rongjun Qu; Changmei Sun; Fang Ma; Zhenzhong Cui; Ying Zhang; Xiaoying Sun; Chunnuan Ji; Chunhua Wang; Ping Yin (pp. 204-210).
► Silica-gels functionalized with dendrimer-like polymers are used as adsorbents. ► We study kinetics and equilibrium forcopper in ethanol solution. ► Pseudo second-order model and Langmuir model are suitable. ► Adsorptions are physical processes. ► Adsorption is endothermic and spontaneous at the solid-solution interface.The adsorption kinetics and equilibrium of silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine (PAMAM) polymers SiO2-G1.0, SiO2-G2.0 and SiO2-G3.0 for Cu2+ in ethanol fuel were investigated by using batch method. The results indicated that the all the adsorptions of the three adsorbents followed well the pseudo second-order model. The adsorption isotherms were fitted by Langmuir model, Freundlich model and Dubinin–Radushkevich (D–R) model. The results showed that Langmuir model was more suitable to describe the equilibrium data than the Freundlich model. From the D–R isotherm model, the mean free energy E calculated of the three adsorbents showed that the adsorptions were taken place by physical processes. Thermodynamic parameters, Δ G0, Δ H0 and Δ S0 indicated the Cu2+ adsorption to be endothermic and spontaneous with decreased randomness at the solid-solution interface, resulting in their higher adsorption capacities at higher temperature. The effect of generation number of PAMAM polymers loaded on silica-gel, contact time, initial concentration and temperatures on the adsorption capabilities were studied in detail. Moreover, the adsorption mechanism of copper from ethanol fuel was also presumed.
Keywords: Silica-gel functionalized with polyamidoamine; Copper ion; Ethanol solution; Kinetics; Equilibrium
Catalytic formation of carbonyl sulfide during warm gas clean-up of simulated coal-derived fuel gas with Pd/γ-Al2O3 sorbents
by Erik C. Rupp; Evan J. Granite; Dennis C. Stanko (pp. 211-215).
The catalytic formation of carbonyl sulfide is observed in simulated fuel gas mixtures. A palladium sorbent can act as a catalyst for the formation of carbonyl sulfide from carbon monoxide and hydrogen sulfide reactants present within fuel gas.Display Omitted► 200-fold increase in COS concentration in fuel gas upon exposure to Pd/γ-Al2O3. ► Hydrolysis of COS has initial impact, but deactivation is observed. ► COS concentration increases with increasing temperature and decreasing flow rate. ► Developed kinetic model capable of capturing experimental trends.Coal gasification processes, such as the Integrated Gasification Combined Cycle (IGCC), will increase in importance due to the expanding concern over CO2 emissions and global climate change. During the development of a Pd/γ-Al2O3 sorbent for warm (200°C) fuel gas cleanup, the catalytic formation of carbonyl sulfide (COS), was observed. This is attributed to a heterogeneous reaction involving fuel gas components (CO/CO2/H2/H2S/H2O) and Pd/γ-Al2O3. The concentration of COS increases 200-fold when exposed to the Pd/γ-Al2O3 sorbent. A Langmuir–Hinshelwood reaction mechanism is proposed and a kinetic model is developed based on experimental results. The effect of γ-Al2O3, a common catalyst for hydrolysis of COS, and H2O on the COS concentration is discussed.
Keywords: Carbonyl sulfide; Hydrogen sulfide; Palladium; Catalyst; Gasification
Geochemical modeling and experimental evaluation of high-pH floods: Impact of Water–Rock interactions in sandstone
by Mahdi Kazempour; Eric Sundstrom; Vladimir Alvarado (pp. 216-230).
► We ran experiments in model and reservoir rocks to demonstrate buffering capacity of minerals. ► We demonstrate that anhydrite, among other minerals, regulates pH and ion profiles in floods. ► Geochemical model predicts well aqueous chemistry during oil recovery with alkaline solutions. ► Upscaling through modeling shows that lab results act as poor predictors of field chemistry.Injection of alkaline solutions in reservoir leads to mineral dissolution and precipitation, possibly resulting in changes in permeability and porosity, and consequently altering solution pH. Accurate prediction of pH, alkali consumption and aqueous chemistry changes are required to design suitable chemical blends in alkaline-polymer (AP) or alkaline-surfactant-polymer (ASP) flooding. Excessive consumption of alkali can result in degradation of flood performance and lower than expected oil recovery. We report state-of-the-art geochemical simulation results for sandstone reservoir mineral assemblages and alkali solutions (NaOH, Na2CO3, and NaBO2) employed in AP and ASP formulations. Single-phase high-pH corefloods were completed using Berea sandstone and reservoir samples to calibrate and validate geochemical simulations. Results show that rock-fluid interactions depend strongly on mineral type and amount, alkaline solution injection flowrate, and composition of the injected and formation water. Anhydrite, a commonly found calcium sulfate, significantly impacts pH buffering capacity, water chemistry and permeability damage against conventional alkali agents in chemical flooding particularly for Na2CO3, but no significant pH buffering is observed during NaBO2 flooding. Experimental data and model results show that the pH-buffering effect is maintained even after several pore volumes of alkaline solution are injected, if a sufficient fraction of relevant minerals is present. The end consequence of this is insufficient alkalinity for reactions with the oil phase and the likely formation damage.
Keywords: Alkaline flood; Anhydrite; pH buffering; Oil recovery; Chemical flooding
Preparation of fatty acid methyl esters from hazelnut, high-oleic peanut and walnut oils and evaluation as biodiesel
by Bryan R. Moser (pp. 231-238).
► Hazelnut, walnut and high-oleic peanut oils were converted into biodiesel. ► They have high lipid production potentials and are suitable for marginal lands. ► Fatty acid composition was a principal factor influencing fuel properties. ► Blends with petroleum diesel fuel were also explored.Refined hazelnut, walnut and high-oleic peanut oils were converted into fatty acid methyl esters using catalytic sodium methoxide and evaluated as potential biodiesel fuels. These feedstocks were of interest due to their lipid production potentials (780–1780Lha−1yr−1) and suitability for marginal lands. Methyl oleate was the principal constituent identified in hazelnut (HME; 76.9%) and peanut (PME; 78.2%) oil methyl esters. Walnut oil methyl esters (WME) were comprised primarily of methyl esters of linoleic (60.7%), oleic (15.1%) and linolenic (12.8%) acids. PME exhibited excellent oxidative stability (IP 21.1h; EN 14112) but poor cold flow properties (CP 17.8°C) due to its comparatively high content of very-long chain fatty esters. WME provided low derived cetane number and oxidative stability (IP 2.9h) data as a result of its high percentage of polyunsaturated fatty esters. HME yielded a satisfactory balance between all fuel properties when compared to the biodiesel standards ASTM D6751 and EN 14214 due to its high content of monounsaturated fatty esters. Also explored were the properties of blends of HME, PME and WME in ultra-low sulfur (<15ppm) diesel (ULSD) fuel and comparison to petrodiesel standards ASTM D975, D7467 and EN 590. With increasing content of biodiesel, the oxidative stability, cold flow properties and calorific value of ULSD was negatively affected, whereas lubricity was markedly improved. Kinematic viscosity, specific gravity and surface tension were impacted to lesser extents by addition of biodiesel to ULSD. In summary, HME, PME and WME are suitable based on their fuel properties as biodiesel fuels and blend components in ULSD.
Keywords: Biodiesel; Diesel fuel; Fatty acid methyl esters; Hazelnut; High-oleic peanut
Biodiesel production over Ca-based solid catalysts derived from industrial wastes
by N. Viriya-empikul; P. Krasae; W. Nualpaeng; B. Yoosuk; K. Faungnawakij (pp. 239-244).
Display Omitted► Industrial waste shells of egg and mollusk as biodiesel production catalysts. ► Optimum preparation condition was a calcination in air at 800°C for 2–4h. ► Transesterification activity strongly corresponded to basic property of the catalyst.The solid oxide catalysts derived from the industrial waste shells of egg, golden apple snail, and meretrix venus were used as biodiesel production catalysts. Their catalytic activity in transesterification of palm olein oils and their physicochemical properties (by TG/DTA, EDX, SEM, N2 sorption, CO2-TPD, and XRD) were systematically investigated. The waste materials calcined in air with optimum conditions (temperature of 800°C, time of 2–4h) transformed calcium species in the shells into active CaO catalysts. The activity of the catalysts was in line with the basic amount of the strong base sites, surface area, and crystalline phase in the catalysts. All catalysts derived from egg and mollusk shells at 800°C provided high activity (>90% fatty acid methyl ester (FAME) in 2h). These abundant wastes showed good potential to be used as biodiesel production catalysts.
Keywords: Transesterification; Heterogeneous catalyst; Egg and mollusk shells; CO; 2; poisoning; Basicity
Reduced coke formation and aromaticity due to chloroperoxidase-catalyzed transformation of asphaltenes from Maya crude oil
by Marcela Ayala; Edna L. Hernandez-Lopez; Lucia Perezgasga; Rafael Vazquez-Duhalt (pp. 245-249).
Asphaltenes from Mexican Maya crude oil generate 45% less coke and display reduced. Aromaticity after chloroperoxidase-catalyzed transformation in the presence of hydrogen peroxide.Display Omitted► Free-porphyrin asphaltenes from heavy crude oil are catalytically oxidized by chloroperoxidase. ► Fluorescence due to aromatic moieties decreases in treated asphaltenes. ► Forty five percentage of less coke is generated under thermal degradation of enzyme-treated asphaltenes. ► Chemical modification improves the enzyme performance in low water content medium.The transformation of the porphyrin-free asphaltene fraction from a heavy Maya crude oil was catalyzed by chloroperoxidase from Caldariomyces fumago (CPO) in a ternary system with low water content of 6.3%. The total turnover number (TTN) in this system was determined for lyophilized CPO in the presence of sucrose as cryoprotector and for a covalent bioconjugate with chitosan. The covalent conjugation of CPO with chitosan increased the TTN by 10-fold. Fluorescence due to aromatic groups decreased by 24% in treated asphaltenes, indicating significant changes after the biotransformation. On the other hand, the solubility profile indicated that transformed asphaltenes are less soluble in toluene and more prone to precipitate in the presence of hexane, compared to untreated asphaltenes, which could be related to the introduction of polar atoms. Energy-dispersive X-ray spectroscopy (EDS) showed that the content of chlorine increased six-fold on an atomic basis. Finally, enzymatically transformed asphaltenes are more reactive and thus generate less coke, as evidenced by thermal degradation under nitrogen atmosphere.
Keywords: Asphaltene; Chloroperoxidase; Reactivity; Coke; Hydrogen peroxide
Development of a new model for biodiesel viscosity prediction based on the principle of corresponding state
by F.R. do Carmo; P.M. Sousa Jr.; R.S. Santiago-Aguiar; H.B. de Sant’Ana (pp. 250-257).
Display Omitted► A new model for predicting viscosities of biodiesel based on the principle of corresponding states was investigated. ► One- and two-reference fluids models were proposed. ► The two-reference fluids model (methyl laurate (C12:0) and methyl oleate (C18:1) as reference fluids) shows best results.A new model for predicting the viscosities of biodiesel is presented in this work. This model is based on the principle of corresponding states, using one- and two-reference fluids. For the critical constants of methyl esters, the Marrero–Gani method was used. For biodiesels, Lee–Kesler’s mixing rules were used for critical constants calculations. The two models studied in this work were compared with Ceriani et al. , Yuan , and Revised Yuan models. A set of data on biodiesel viscosity was used in this work, consisting of 31 pure biodiesels and 4 mixtures of biodiesel (totalizing 193 experimental data). The best result was found using a two-reference-fluids model, methyl laurate (C12:0) and methyl oleate (C18:1), with a global average relative deviation of 6.66%.
Keywords: Biodiesel; Viscosity; Prediction; Model; Principle of corresponding states
Acetaldehyde and formaldehyde concentrations from sites impacted by heavy-duty diesel vehicles and their correlation with the fuel composition: Diesel and diesel/biodiesel blends
by Marina C. Rodrigues; Lílian L.N. Guarieiro; Manuela P. Cardoso; Luiz Souza Carvalho; Gisele O. da Rocha; Jailson B. de Andrade (pp. 258-263).
► Formaldehyde and acetaldehyde emissions were related to fuel composition. ► Data from other sites impacted by heavy-duty vehicles were used for comparison. ► Two major groups were observed by using PCA. ► Addition of biodiesel to diesel showed an increase of carbonyl concentration profile.The increasing of both industrialization and motorization of the world has led to a sharp rise in the demand for fossil fuels. Concern about the environmental impact caused by burning of these fuels has involved researchers that became engaged in assessing the damages of pollution not only to environment, but also to human health. In this study, carbonyl compounds (CC) were measured in vapor samples from a place impacted by heavy-duty vehicles (Bus Station) fuelled with diesel/biodiesel fuel blend (B5) in Salvador, Brazil. Among them, formaldehyde, acetaldehyde and propanone were the most abundant quantified compounds. Concentration levels (ppbV) for major CC detected during the sampling period ranged from 28.45 to 287.3 (formaldehyde), 24.91 to 171.3 (acetaldehyde) and 5.835 to 72.29 (propanone). The obtained data in this site was compared to formaldehyde and acetaldehyde concentrations found in other sites impacted by heavy-duty vehicles fuelled with pure diesel and diesel/biodiesel blends. All data were used to make a possible correlation with formaldehyde/acetaldehyde ratio and the relationship with the kind of fuel used by these vehicles. PCA was used to verify possible grouping among 19 sites impacted by heavy-duty vehicles and showed two major groups, one characterized by being strongly impacted and the other with a low contribution of heavy-duty vehicles. Thus, the addition of higher concentrations of biodiesel to diesel showed an improvement in the carbonyl concentration profile at places with high circulation of heavy-duty vehicles, which had similar profile to those found for sites less impacted by these kind of vehicles.
Keywords: Carbonyl compounds; Vehicular exhaust; Diesel; Biodiesel; Diesel engine
Electrochemically assisted demetallisation of model metalloporphyrins and crude oil porphyrinic extracts in emulsified media, by using active permeated atomic hydrogen
by D. Acevedo; Luis F. D’Elia Camacho; Jorge Moncada; Z. Puentes (pp. 264-270).
► Hydrodesmetallisation reactions, under mild conditions, are assisted by electrochemically produced atomic hydrogen. ► Compared with nonemulsified medium, electrochemically assisted hydrodemetallisation is favoured in emulsified media. ► Pd foils, permeable to atomic hydrogen, are reusable in electrochemically assisted hydrodemetallisation reactions. ► Emulsified media play a promoting role. Vanadium and nickel are transferred from oil to water phases during reactions.Electrochemically assisted metalloporphyrins demetallisation can be performed employing a unique palladium membrane without surface deactivation; in other words, palladium foils can be used several times. Vanadyl tetraphenylporphyrin (VO-TPP) or nickel tetraphenylporphyrin (Ni-TPP) dissolved in CH3Cl (nonemulsified media) are converted, producing hydrogenated porphyrins and/or free metal (Ni or V), by active permeated atomic hydrogen generated by applying −1.92mAcm−2 at 25°C. VO-TPP and Ni-TPP conversions are dramatically increased when reactions are carried out in the following Oil/Water (O/W) emulsified media (about 30% in emulsified media vs. 5% in nonemulsified medium): (i) CHCl3/H2O; (ii) CHCl3/1×10−5M HCl (pH=5); (iii) CHCl3/1×10−5M HCl (pH=5)+4×10−4M EDTA and (iv) CHCl3/4×10−4M EDTA. Moreover, VO-TPP and Ni-TPP demetallisation percentages depend on the water phase nature, the highest demetallisation percentage (71%) is achieved using HCl+EDTA as water phase. Crude oil porphyrinic extracts seem to be less reactive than model metalloporphyrins.
Keywords: Atomic hydrogen; Demetallisation; Hydrotreating; Crude oil porphyrinic extracts; Electrochemically assisted reactions
NMR analysis of the transformation of wood constituents by torrefaction
by T. Melkior; S. Jacob; G. Gerbaud; S. Hediger; L. Le Pape; L. Bonnefois; M. Bardet (pp. 271-280).
► Torrefaction of wood samples in analytical device. ► NMR and EPR investigations on raw and thermally treated wood samples. ► Identification of the transformations of the wood polymers. ► Relation between the torrefaction temperature and the observed transformations.The injection of biomass in a pressurised entrained flow reactor is challenging. Biomass preparation by torrefaction before gasification could be a suitable option to improve it. Transformation of the material induced by this treatment lead to interesting features: increased brittleness, improved fluidisation properties of the powder, hydrophobicity, higher energy content. The major biomass constituents, cellulose, hemicelluloses and lignin are variously affected by torrefaction, depending on their respective reactivity. The objective of this work is to investigate the transformation of the biomass constitutive polymers induced by this thermal treatment. For that purpose, both solid-state NMR and EPR investigations have been performed on wood samples (beech) torrefied at different temperatures ranging from 200°C to 300°C. The results of these investigations have been compared with data obtained on untreated wood. These characterizations have brought to light different transformations of the polymers: de-acetylation of hemicelluloses, demethoxylation of lignin, changes in the cellulose structure. Furthermore, the temperature at which depolymerisation of the different components begins to occur has been identified.
Keywords: Biomass; Lignocellulosic fuel; Torrefaction; Wood; CPMAS; 13; C NMR
Evaluation of several methods of extraction of oil from a Jordanian oil shale
by Yi Fei; Marc Marshall; W. Roy Jackson; Martin L. Gorbaty; Mohammad W. Amer; Peter J. Cassidy; Alan L. Chaffee (pp. 281-287).
► Various methods for extracting a Jordanian oil shale were compared. ► High recovery of organic matter was obtained at relatively low temperature (355°C). ► The oil/asphaltene ratio was improved at 425°C. ► Small amounts of added water were beneficial, but larger amounts reduced yields. ► A number of catalysts examined did not benefit oil yields.A Jordanian oil shale from the El Lajjun deposit has been reacted with N2, H2 and CO in the presence and absence of water in the temperature range 300–425°C. The effect of adding Fe, Cu, Ni, Sn and NaAlO2 as potential catalysts to some of these reactions has been studied but none led to improved oil yields. Most of the organic material in the oil shale was converted to asphaltene at 355°C, but the oil yield was low at this temperature. At 425°C nearly all the organic product was in the form of oil.
Keywords: Oil extraction; High temperature; High pressure; Solvent separation; Gas chromatography
Non-catalytic vanadium removal from vanadyl etioporphyrin (VO-EP) using a mixed solvent of supercritical water and toluene: A kinetic study
by Pradip Chandra Mandal; Wahyudiono; Mitsuru Sasaki; Motonobu Goto (pp. 288-294).
Reaction kinetics of the decomposition of vanadyl etioporphyrin (VO-EP) in supercritical water (SCW) under toluene environment was explored in this study to remove vanadium. This is a green process and has not been previously reported prior to this study. Symbols: □, 490°C; ◊, 450°C; Δ, 410°CDisplay Omitted► Supercritical water is capable of removing vanadium from vanadyl etioporphyrin (VO-EP) without the addition of catalyst. ► This environmental friendly process was acceptable due to the absence of catalyst and short reaction time. ► Overall VO-EP conversion and vanadium removal are 90.51% and 80.26% respectively. ► We proposed a kinetic model fitted with the experimental results following free radical mechanism.Reaction kinetics and mechanisms of the decomposition of vanadyl etioporphyrin (VO-EP), the most common metal compounds present in heavy crude, were studied in a mixed solvent of supercritical water (SCW) and toluene without the addition of any catalyst, H2 or H2S to remove vanadium. The aim of this study was to remove vanadium an environmentally benign way from VO-EP at a high extent and in a short reaction time. The experiments were conducted in an 8.8mL batch reactor fabricated from Hastelloy C-276. The capability of SCW to remove vanadium from VO-EP was discovered at temperatures of 410–490°C and a water partial pressure (WPP) of 25MPa. Experimental results revealed that the overall VO-EP conversion was 90.51% at a temperature of 490°C, WPP of 25MPa and reaction time of 180min. Under the same reaction conditions, approximately 80.26% vanadium was removed by reaction with SCW. The global reaction followed first order kinetics, with Arrhenius parameters of activation energy 8.93kcal/mol and a pre-exponential factor 5.66s−1. A kinetic model of demetallation that well-fit the experimental results, was proposed. The reaction kinetics may be critically explained in terms of free radical mechanism. The obtained results suggest that SCW is capable of removing vanadium from VO-EP.
Keywords: Vanadyl etioporphyrin; Batch reactor; Demetallation; Reaction kinetics; Arrhenius parameters
Experimental study on performance and emissions of a high speed diesel engine fuelled with n-butanol diesel blends under premixed low temperature combustion
by Gerardo Valentino; Felice E. Corcione; Stefano E. Iannuzzi; Simone Serra (pp. 295-307).
► Low cetane diesel–butanol fuel blends and engine management. ► Partially Premixed Compression Ignition (PPCI). ► Effect of fuel properties on engine performance and emissions. ► Fuel design strategies for the control of PPCI combustion. ► Alternative fuels for diesel engines.In the present paper, results of an experimental investigation carried out in a modern diesel engine running at different operative conditions and fuelled with blends of diesel and n-butanol, are reported. The exploration strategy was focused on the management of the timing and injection pressure to achieve a condition in which the whole amount of fuel was delivered before ignition. The aim of the paper was to evaluate the potential to employ fuel blends having low cetane number and high resistance to auto-ignition to reduce engine out emissions of NO x and smoke without significant penalty on engine performance. Fuel blends were mixed by the baseline diesel (BU00) with 20% and 40% of n-butanol by volume. The n-butanol was taken by commercial production that is largely produced through petrochemical pathways although the molecule is substantially unchanged for butanol produced through biological mechanisms.The experimental activity was performed on a turbocharged, water cooled, DI diesel engine, equipped with a common rail injection system. The engine equipment includes an exhaust gas recirculation system controlled by an external driver, a piezo-quartz pressure transducer to detect the in-cylinder pressure signal and a current probe to acquire the energizing current to the injectors. Engine tests were carried out at 2500rpm and 0.8MPa of BMEP exploring the effect of start of injection, O2 concentration at intake and injection pressure on combustion behavior and engine out emissions. The in-cylinder pressure and rate of heat release were investigated for the neat diesel and the two blends to evaluate engine performance and exhaust emissions both for the conventional diesel and the advanced premixed combustion processes.The management of injection pressure, O2 concentration at intake and injection timing allowed to realize a partial premixed combustion by extending the ignition delay, particularly for blends. The main results of the investigation made reach smoke and NO x emissions due to the longer ignition delay and a better mixing control before combustion. The joint effect of higher resistance to auto ignition and higher volatility of n-butanol blends improved emissions compared to the neat diesel fuel with a low penalty on fuel consumption.
Keywords: Diesel LTC combustion; Low cetane diesel–butanol fuel blend; Premixed combustion; NO; x; Smoke
Study of ash deposition during coal combustion under oxyfuel conditions
by L. Fryda; C. Sobrino; M. Glazer; C. Bertrand; M. Cieplik (pp. 308-317).
► Ash deposition of Russian coal and lignite under oxyfuel and air combustion. ► XRD and ICP analyses of deposited and filter ash (fine ash). ► Higher deposition propensity under oxyfuel: evaluation of influence factors. ► Flue gas properties and ash particle size seem to affect deposition phenomena.This paper presents a comparative study on ash deposition of two selected coals, Russian coal and lignite, under oxyfuel (O2/CO2) and air combustion conditions. The comparison is based on experimental results and subsequent evaluation of the data and observed trends. Deposited as well as remaining filter ash (fine ash) samples were subjected to XRD and ICP analyses in order to study the chemical composition and mineral transformations undergone in the ash under the combustion conditions. The experimental results show higher deposition propensities under oxyfuel conditions; the possible reasons for this are investigated by analyzing the parameters affecting the ash deposition phenomena. Particle size seems to be larger for the Russian coal oxy-fired ash, leading to increased impaction on the deposition surfaces. The chemical and mineralogical compositions do not seem to differ significantly between air and oxyfuel conditions.The differences in the physical properties of the flue gas between air combustion and oxyfuel combustion, e.g. density, viscosity, molar heat capacity, lead to changes in the flow field (velocities, particle trajectory and temperature) that together with the ash particle size shift seem to play a role in the observed ash deposition phenomena.
Keywords: Oxyfuel; Combustion; Pulverized fuel; Ash deposition
Role of phosphorus in carbon matrix in desulfurization of diesel fuel using adsorption process
by Mykola Seredych; Chi Tang Wu; Patrice Brender; Conchi O. Ania; Cathie Vix-Guterl; Teresa J. Bandosz (pp. 318-326).
Display Omitted► Pyrophosphates and P2O5 in small mesopores enhance the desulfurization efficiency. ► Dibenzothiophenes are strongly and selectively adsorbed. ► Phosphorus inhibits oxidation of dibenzothiophenes. ► Dispersive and acid–base interactions and acid–base govern the desulfurization process.Adsorptive removal of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model diesel fuel with 20ppm w total concentration of sulfur was investigated on polymer-derived carbons with incorporated heteroatoms of oxygen, sulfur and phosphorus. The materials before and after exposure to model diesel fuel were characterized using adsorption of nitrogen, thermal analysis, potentiometric titration, XPS and elemental analysis. The selectivities for DBT and DMDBT adsorption were calculated with reference to naphthalene. The results indicated that the presence of phosphorus, especially in the form of pyrophosphates and P2O5, increases the capacity and selectivity for removal of dibenzothiophenes. It also affects the adsorption mechanism. Phosphorus suppresses oxidation reactions of DBT and DMDBT. Owing to a possible location of bulky phosphorus groups in pore with sizes between 1 and 3nm thiophenic molecules are strongly adsorbed there via dispersive forces. Acidic environment also enhances adsorption via acid–base interactions. Physical adsorption mechanism and stability of surface make these carbons attractive candidates for thermal regeneration.
Keywords: Dibenzothiophenes; Model diesel fuel; Activated carbon; P-functionalities; Reactive adsorption
Microwave-heated pyrolysis of waste automotive engine oil: Influence of operation parameters on the yield, composition, and fuel properties of pyrolysis oil
by Su Shiung Lam; Alan D. Russell; Chern Leing Lee; Howard A. Chase (pp. 327-339).
Microwave-heated pyrolysis offers an exciting green approach to the treatment and recycling of used automotive engine oil – a promising technology to convert the waste oil to gasoline-like oil product.Display Omitted► Microwave-heated pyrolysis of waste automotive engine oil was investigated. ► The process generates an 88 wt.% yield of gasoline-like oil product. ► The oil product contains valuable light aliphatic and aromatic hydrocarbons. ► The oil product contains low levels of sulphur, oxygen, and toxic PAH compounds. ► Feed rate, purge-gas flow, and heating source affect product yield and composition.The pyrolysis of waste automotive engine oil was investigated using microwave energy as the heat source, and the yield and characteristics of the pyrolysis oils (i.e. elemental analysis, hydrocarbon composition, and potential fuel properties) are presented and discussed. The microwave-heated pyrolysis generated an 88 wt.% yield of condensable pyrolysis oil with fuel properties (e.g. density, calorific value) comparable to traditional liquid transportation fuels derived from fossil fuel. Examination of the composition of the oils showed the formation of light aliphatic and aromatic hydrocarbons that could also be used as a chemical feedstock. The oil product showed significantly high recovery (90%) of the energy present in the waste oil, and is also relatively contaminant free with low levels of sulphur, oxygen, and toxic PAH compounds. The high yield of pyrolysis oil can be attributed to the unique heating mode and chemical environment present during microwave-heated pyrolysis. This study extends existing findings on the effects of pyrolysis process conditions on the overall yield and formation of the recovered oils, by demonstrating that feed injection rate, flow rate of purge-gas, and heating source influence the concentration and the molecular nature of the different hydrocarbons formed in the pyrolysis oils. The microwave-heated pyrolysis can be performed in a continuous operation, and the apparatus described which is fitted with magnetrons capable of delivering 5kW of microwave power is capable of treating waste oil at a feed rate of 5kg/h with a positive energy ratio of 8 (energy content of hydrocarbon products/electrical energy supplied for microwave heating) and a net energy output of 179,390kJ/h. Our results indicate that microwave-heated pyrolysis shows exceptional promise as a means for recycling and treating problematic waste oil.
Keywords: Pyrolysis; Microwave pyrolysis; Waste oil; Pyrolysis oil; Fuel
High temperature pretreatment and hydrolysis of cotton stalk for producing sugars for bioethanol production
by Parameswaran Binod; Mathiyazhakan Kuttiraja; Mohan Archana; Kanakambaran Usha Janu; Raveendran Sindhu; Rajeev K. Sukumaran; Ashok Pandey (pp. 340-345).
► NaOH pretreatment of cotton stalk was effective for producing fermentable sugars. ► High temperature treatment completely removed lignin. ► The process efficiency was 53%.The aim of this work was to evaluate cotton stalk (waste plant material after harvesting the cotton) as feedstock for bioethanol production. Different pretreatment strategies were tried using sodium hydroxide in a high pressure reactor equipped with a pitch blade turbine stirrer, followed by enzymatic hydrolysis using cellulases; the process optimization was carried out using Taguchi experimental design. Best results were achieved when the pretreatment was carried out at 180°C for 45min with mixing of substrate at 100rpm. The sugar yield was evaluated based on pretreatment severity. The hydrolysis efficiency of pretreated cotton plant waste was very good (96%), showing the excellent efficiency of the method in removing the lignin. The material balance in each stage of the process was estimated and the total process efficiency was found to be 53% based on glucose conversion.
Keywords: Cotton stalk; Lignocellulosic material; Bioethanol; Pretreatment severity; Enzymatic hydrolysis
Gasification reactivity of char from dried sewage sludge in a fluidized bed
by Susanna Nilsson; Alberto Gómez-Barea; Diego Fuentes Cano (pp. 346-353).
► Gasification reactivity of sewage sludge char with CO2 and H2O in fluidized bed. ► Analytical expressions useful for fluidized bed gasification. ► Assessment of influence of char preparation method and diffusion effects.The gasification reactivity of char from dried sewage sludge (DSS) applicable to fluidized bed gasification (FBG) was determined. The char was generated by devolatilizing the DSS with nitrogen at the selected bed temperature and was subsequently gasified by switching the fluidization agent to mixtures of CO2 and N2 (CO2 reactivity tests) and steam and N2 (H2O reactivity tests).. The tests were conducted in the temperature range of 800–900°C at atmospheric pressure, using partial pressure of the main reactant in the mixture (CO2 or H2O) in the range of 0.10–0.30bar. Expressions for the intrinsic reactivity (free of diffusion effects) as a function of temperature, partial pressure of gas reactant (CO2 or H2O) and degree of conversion were obtained for each reaction. For the whole range of conversion it was found that the char reactivity in an H2O–N2 mixture was roughly three times higher than that in a mixture with the corresponding partial pressure of CO2. The reactivity was only influenced by particle size greater than 1.2mm in the tests with steam at 900°C. It was demonstrated that the method of char preparation greatly influences the reactivity, highlighting the importance of generating the char in conditions similar to that in FBG.
Keywords: Gasification; Kinetics; Sewage sludge; Char; Modeling
Near infrared reflectance spectroscopy and multivariate analysis to monitor reaction products during biodiesel production
by Sara Pinzi; Fernando Alonso; Juan García Olmo; M. Pilar Dorado (pp. 354-359).
► We develop a NIRS-based technology to predict glycerides and ester yield in biodiesel. ► Glycerides and ester yield are key factors to determine biodiesel quality. ► NIRS is found to be a valuable tool to predict conversion yield in biodiesel. ► Grouping of samples is allowed using principal component analysis.In agreement with the principles of green chemistry, near infrared spectroscopy (NIRS) allows multi-component analysis in a fast and nondestructive way, without requiring complex pre-treatments, being a safe, clean and energy saving technique. In this work, a preliminary study to develop near infrared calibration models to predict methyl esters (ME) yield, monoglycerides (MG), diglycerides (DG), triglycerides (TG), free glycerol (FG) and total glycerol (TotalG) content in biodiesel has been carried out. These parameters are considered key factors to determine biofuel quality, its commercialization and to study and monitor the transesterification reaction. For this purpose, samples of biodiesel produced from three different vegetable oils (maize oil, sunflower oil and olive–pomace oil) were analyzed following the EN14103 and EN14105 European standards as reference methods. NIRS calibration equations were validated with a group of validation samples. The mean spectra showed that the main variability on biodiesel NIR spectra occurred around 1700 and 2300nm. Moreover, the principal components analysis (PCA) applied to the spectra revealed the grouping of samples according to the type of oils used for biodiesel production. The standard deviation of the prediction (cross validation) errors (RMSEPCV) of the calibration models and the standard deviation error (RMSEP) of the validation set resulted similar to the measurement errors (intra lab SEL r) and repeatability (inter lab SEL R) of each analyte. Results confirm the accuracy of the developed NIRS models for determination of glycerides content and methyl esters yield in biodiesel.
Keywords: Methyl esters; Vegetable oil; Transesterification; Glyceride; Biodiesel quality
A new insight into the role of transition metals doping with CeO2–ZrO2 and its application in Pd-only three-way catalysts for automotive emission control
by Guangfeng Li; Qiuyan Wang; Bo Zhao; Renxian Zhou (pp. 360-368).
Display Omitted► The introduction of Fe or Co promotes the surface atom ratios of Ce/Zr. ► The introduction of Fe or Co makes the part of Ce4+ transferred into Ce3+. ► The increasing of oxygen vacancies for CZFe leads to the enhancement of DOSC. ► Pd/CZFe and Pd/CZCo are active in promoting the three-way catalytic performance.CeO2–ZrO2 (CZ) doped with different transition metals was prepared through a co-precipitation and supercritical drying method and the corresponding Pd-only TWCs were characterized. Pd/CZFe and Pd/CZCo exhibit the best catalytic activity and the widest operation window, in accordance with the decrease of the light-off and full-conversion temperature. However, Pd/CZCr restrains the catalytic property. It may be due to the different effect of transition metals on the property of CZ. The introduction of Fe and Co promotes the surface atom ratios of Ce/Zr, makes part of Ce4+ transferred into Ce3+ in order to maintain the electrical neutrality and seems to facilitate the reduction of Ce4+→Ce3+ or the formation of oxygen vacancies of CZ. The increasing concentration of oxygen vacancies for CZFe leads to the enhancement of DOSC. Moreover, the introduction of Fe favors the transfer of oxygen in different atmospheres.
Keywords: Dynamic oxygen mobility; CeO; 2; –ZrO; 2; Transition metals; In situ Raman; Pd-only three-way catalysts
An effect of tar model compound toluene treatment with high-temperature flames
by Mikhail Granovskii; Regan Gerspacher; Todd Pugsley; Francisco Sanchez (pp. 369-372).
► Treatment of model tar compound toluene with acetylene and hydrogen oxy-flames. ► Both flames promote toluene reforming into H2 and CO (syngas). ► Both heat supply and interaction with combustion products advance toluene reforming. ► Utilization of the hydrogen/oxygen flame is similar to the application of plasma steam.A major drawback of renewable gasification technologies is contamination of the syngas produced with “tar”, which can induce fouling in downstream equipment. The effect of continuous injection of acetylene and hydrogen high-temperature flames into the blend of gases containing a tar model compound toluene in order to decompose the latter has been studied. The experimental results indicate that treatment of the reaction mixture with the acetylene and hydrogen oxy-flames promotes reforming of toluene into H2 and CO. The same heating values of the flames result in different ratios between H2 and CO; this points out on a difference in mechanism of that reforming implying an interaction between toluene and combustion products which include a large specter of intermediate species (radicals). A better understanding of these mechanisms will help to obtain an optimal ratio between external oxy-flame and internal combustion regularly employed to increase the temperature of the producer gas in order to decompose volatile organics and tars in it. Utilization of oxy-flames for high-temperature clean-up of producer gas (gasification products) is very similar to the application of plasma steam tested with positive results in semi-industrial gasification units.
Keywords: Combustion; Gasification; Biomass tar; Steam reforming; Toluene
Trace precious metal Pt doped plate-type anodic alumina Ni catalysts for methane reforming reaction
by Lu Zhou; Yu Guo; Jian Chen; Makoto Sakurai; Hideo Kameyama (pp. 373-376).
► Plate-type structured catalysts. ► Intelligent catalysts showed self-activation and self-regeneration ability. ► Multiple-applied catalyst for SRM, CMR and POM.A novel plate-type anodic alumina supported 17.9 wt% Ni/Al2O3/alloy showed a quick deactivation in daily start-up and shut down (DSS) steam reforming of methane (SRM) at 700°C, because of the Ni oxidation reaction with steam. When 0.078 wt% Pt was doped, the catalyst exhibited self-activation and self-regeneration ability, while 3000h continual and 500-time DSS stability was testified. Further, this Pt–Ni catalyst also showed excellent reactivity during carbon dioxide reforming of methane (CMR) and partial oxidation of methane reaction (POM). According to the TPR and XRD analyses, the H2 spillover effect and the formation of Pt–Ni alloy were believed to be the main reason for the reactivity improvement of this catalyst.
Keywords: Reforming; Alumite support; Methane; Daily start-up and shut-down
An optimum biodiesel combination: Jatropha and soapnut oil biodiesel blends
by Yi-Hung Chen; Tsung-Han Chiang; Jhih-Hong Chen (pp. 377-380).
► Soapnut oil and jatropha oil methyl esters shows the complementary fuel properties. ► A SNME–JME blending ratio of 35:65 by weight satisfy all biodiesel specifications. ► The biodiesel–diesel blends up to B40 would show the satisfactory fuel properties.Jatropha ( Jatropha curcas) and soapnut ( Sapindus mukorossi) oils are considered potential non-edible oil feedstocks for biodiesel production and present complementary fuel properties. Apparently, the poor oxidation stability of jatropha oil biodiesel and the high cold filter plugging point of soapnut oil biodiesel can be successfully improved to satisfy all biodiesel specifications at an optimum blending ratio. The optimum biodiesel combination was further blended with diesel at various volumetric percentages to evaluate the variations of fuel properties. The biodiesel–diesel blends up to B40 would show the satisfactory fuel properties.
Keywords: Soapnut oil; Jatropha oil; Diesel; Cold filter plugging point; Oxidation stability