Fuel Processing Technology (v.131, #C)
Editorial Board (IFC).
Catalytic effects of Zr doping ion on ceria-based catalyst by Ce Zhang; Xiao-Dong Wen; Bo-Tao Teng; Yun Zhao; Maohong Fan (1-6).
Exploring the catalytic effects of Zr doping ion on ceria-based catalysts and its corresponding oxidation mechanism are of great significance. Using density functional theory method, the possible oxygen species and their catalytic roles on Ce1 − xZrxO2(111) surfaces are systematically investigated. For O2 adsorbed on the stoichiometric Ce1 − xZrxO2(111), it remains the electronic character of free molecule. When O2 adsorbs at the top site of Ce on the partially reduced Ce1 − xZrxO2(111), a paramagnetic superoxide forms; while a diamagnetic peroxide appears if O2 fills into the surface oxygen vacancy. Using CO as a probe molecule, the oxidation mechanism on Ce1 − xZrxO2(111) is explored. Our results indicate that CO is directly oxidized to CO2 by superoxide; while a tridentate carbonate forms when CO reacts with peroxide. Compared with ceria, one of the most important catalytic effects of doped Zr ion is to lower the oxygen vacancy formation energy and improve its oxidative activity.Electronic formation mechanism of O2 − and O2 2− on the partially reduced Ce1 − xZrxO2(111).Display Omitted
Keywords: Ce1 − xZrxO2; Density functional theory; Oxygen species; Catalytic oxidation;
A conceptual design by integrating dimethyl ether (DME) production with tri-reforming process for CO2 emission reduction by Yishan Zhang; Shujing Zhang; Tracy Benson (7-13).
There has been considerable interest in the development of more efficient processes for conversion and utilization of CO2. Tri-reforming, as a new approach for the treatment of CO2 in flue stack gases, has been studied in this work. Tri-reforming process combines CO2 reforming with steam methane reforming and methane oxidation to produce syngas (H2 and CO) at a suitable ratio. To determine the optimum operating conditions for the production of syngas with a target ratio and maximized CO2 conversion, the effects of various factors including reaction temperature, reactor pressure and CH4 flow rate on the compositions of syngas obtained from tri-reforming process are investigated. Also, the production of dimethyl ether (DME) from syngas has been rigorously simulated. An optimum heat exchange network was obtained with the objective of minimizing utility cost, which was calculated by General algebraic modeling system (GAMS). Results show that tri-reforming coupled to DME synthesis is an economically feasible approach for the treatment and utilization of CO2 in flue stack gases.
Keywords: CO2 treatment; Tri-reforming; Dimethyl ether; Heat integration;
Carbon dioxide absorption behavior in 2-(ethylamino)ethanol aqueous solutions by I. Folgueira; I. Teijido; A. García-Abuín; D. Gómez-Díaz; A. Rumbo (14-20).
The present study aims to analyze the carbon dioxide absorption process in a chemical solvent based on 2-(ethylamino)ethanol, which is not commonly used in industry for this purpose, but it allows extracting interesting conclusions about the influence of absorption regime, physical properties or reagent chemical structure upon both hydrodynamic and mass transfer behavior in a bubble reactor. The influence of gas flow-rate upon bubble size distribution or gas hold-up allows understanding how the behavior of this type of reactors is and how they can influence the overall process. In this way, in analyzing the predominant reaction mechanism, the behavior of mass transfer coefficient can be known and understood as to why, for this kind of chemical solvent, a dramatic decrease of this coefficient is produced only with the presence of a small amount of amine.Display Omitted
Keywords: Bubble reactor; Hydrodynamic; Absorption; EAE; NMR; Mass transfer coefficient;
Syngas production by partial oxidation of methane in a microchannel reactor over a Ni–Pt/La0.2Zr0.4Ce0.4Ox catalyst by L.L. Makarshin; V.A. Sadykov; D.V. Andreev; A.G. Gribovskii; V.V. Privezentsev; V.N. Parmon (21-28).
Operation of a microchannel reactor during the partial oxidation of methane has been studied. Methods for the deposition of a durable (Ni–Pt)/LaCeZrO catalyst on the Fecralloy microchannel plates working under thermocycling (up to 900 °C) conditions up were developed. It was shown that the temperature profile along the microchannel plate length is not flat. A part of methane is combusted into H2O and CO2 at the front edge of the microchannel plate, which is accompanied by a big heat release. On the rest part of the microchannel plate, endothermic reactions of methane steam and dry reforming occur yielding CO and Н2. As a result, the front edge of the microchannel plate (up to 2 mm in length) undergoes a heavy thermal corrosion. Test runs of the microchannel reactor with one microchannel plate demonstrated 82% methane conversion and 60% selectivity toward carbon monoxide at gas space velocity of 820,000 h− 1. Scaling of the MC reactor increased hydrogen production proportionally to the number of the MC plates. The specific hydrogen production related to the volume occupied by the MC plates is about 123 L/(h·cm3).
Keywords: Microchannel reactor; Microchannel plate; Methane; Partial oxidation; Syngas; Hydrogen production;
Transesterification of sunflower oil with ethanol using sodium ethoxide as catalyst. Effect of the reaction conditions by B.S. Sánchez; B. Benitez; C.A. Querini; G. Mendow (29-35).
Typically, biodiesel is produced using vegetable oil and methanol as raw materials, and sodium methoxide as catalyst, whereupon the obtained product is composed of methyl esters. However, the use of ethyl esters as biodiesel presents many advantages compared to the methyl esters. In this work, the transesterification with ethanol to produce ethyl esters using sodium ethoxide as catalyst was studied. The effect of temperature and alcohol and catalyst concentration on the reaction conversion was investigated, in order to optimize these parameters while also meeting the quality standards.It was found that the optimal reaction conditions are: 1.6 wt.% sodium ethoxide, 25 v/v% ethanol and 55 °C, which allow obtaining a biodiesel composed 100% by ethyl esters that complies with the international quality standards. On the other hand, it was observed that methanolysis reactions are faster than the ethanolysis and sodium methoxide catalyst is more active than the corresponding ethoxide, due to the higher steric hindrance of the ethoxi-radical and to the more intense saponification of sodium ethoxide in ethanol medium.
Keywords: Sodium ethoxide; Biodiesel; Ethanol; Ethyl ester;
Structural stability and oxygen permeability of BaCo0.7Fe0.2M0.1O3 − δ (M = Ta, Nb, Zr) ceramic membranes for producing hydrogen from coke oven gas by Hongwei Cheng; Weilin Yao; Xionggang Lu; Zhongfu Zhou; Chonghe Li; Jizhong Liu (36-44).
The perovskite-type oxygen-transporting membranes of BaCo0.7Fe0.2M0.1O3 − δ (M = Ta, Nb, Zr) were prepared by solid state reaction methods and used for producing hydrogen from coke oven gas (COG). The structural stability of the membranes was characterized systematically using XRD, H2-TPR, O2-TPD, TG–DSC, and SEM-EDXS. Meanwhile, the oxygen permeation flux of the membranes was measured at different temperatures under He or CO2 containing atmosphere. It can be concluded that the Ta-substituting BaCo0.7Fe0.2M0.1O3 − δ is a promising candidate of the membrane materials for producing hydrogen through the catalytic partial oxidation of COG.
Keywords: Perovskite; Oxygen permeation membrane; Structural stability; Partial oxidation; Hydrogen production;
Evaluation of the potential of retrofitting a coal power plant to oxy-firing using CFD and process co-simulation by Y. Fei; S. Black; J. Szuhánszki; L. Ma; D.B. Ingham; P.J. Stanger; M. Pourkashanian (45-58).
A new approach has been developed in order to estimate the potential of retrofitting an existing power plant to oxy-firing and the safe operation regime of the retrofitted boiler under oxy-combustion condition has been determined. Computational Fluid Dynamics (CFD) techniques have been employed to simulate the coal combustion and heat transfer to the furnace water walls and heat exchangers under air-firing and oxy-firing conditions. A set of reduced order models (ROM) has been developed to link the CFD predictions to the whole plant process model in order to simulate the performance of the power plant under different load and oxygen enrichment conditions in an efficient manner. Simulation results of a 500° MWe power plant unit indicate that it is possible to retrofit it to oxy-firing without affecting its overall performance. Further, the feasible range of oxygen enrichment for different power loads is identified to be between 25% and 27%. However, the peak temperature on the superheater platen 2 may increase in the oxy-coal mode at a high power load beyond 450° MWe.
Keywords: CFD; Combustion; Oxy-coal; Process simulation; Reduced order model (ROM);
Computational modelling of the condensation of fast pyrolysis vapours in a quenching column. Part A: Hydrodynamics, heat transfer and design optimisation by V. S. Kiran Kumar Palla; K. Papadikis; S. Gu (59-68).
Direct contact heat exchangers (quenching columns) are considered to be the optimum types of heat exchangers for the fast pyrolysis process. In this study, the hydrodynamics and heat transfer characteristics of a bench scale quenching column are presented. These have been compared with the experimental observations on flooding phenomena which are reported when the quenching column is operated at the design gas flow rates of the fast pyrolysis reactor. The quenching column was found to operate without flooding at 10% of the design flow rate, while flooding was still present even at 50% of the design gas flow rate. Four different design configurations, which are different in terms of weirs and hole placement on the disc and donut plates, are modelled and tested under full gas flow rate conditions. All four cases show normal quenching column operation without any flooding phenomena present and a gas flow time of less than 1 s. The pressure drop across the system was considerably reduced to 15Pa in the modified configuration compared to 90Pa in the baseline model. The hydrodynamic and heat transfer characteristics are thoroughly analysed and proposed optimal design configuration for the effective quenching operation.
Keywords: Quenching column; Hydrodynamics; Heat transfer; Fast pyrolysis;
A techno-economic evaluation of a small-scale fluidized bed gasifier for solid recovered fuel by Umberto Arena; Fabrizio Di Gregorio; Gianfranco De Troia; Alessandro Saponaro (69-77).
This paper reports a technical assessment for an air gasification plant for energy recovery from 5000 t/y of a solid recovered fuel (SRF). This was obtained as one of the output streams from a sorting platform of municipal solid waste, which aims to minimize the utilization of the annexed landfill. The case study analysis was based on data provided by a pilot-scale bubbling fluidized bed gasifier, having a feedstock capacity of about 70 kg/h of the obtained SRF. The tests indicate that the SRF can be converted into a syngas of valuable quality for energy applications. A plant configuration, which includes a bubbling fluidized bed reactor, a mild combustor, a 400 kWe Organic Rankine Cycle generator and an air pollution control system, was defined and described in detail. The standard accounting items related to investment and operating costs were estimated on the basis of official manufacturer's specifications and information: they indicate an economic sustainability only in presence of an incentive tariff for energy production. A material flow analysis indicates that the implementation of the small-scale gasifier could allow a landfill volume saving of more than 10,000 m3/y.
Keywords: Gasification; Solid recovered fuel; Fluidization; Waste-to-energy; Technical and economic analysis; Landfill volume saving;
Desulfurization of model diesel by extraction/oxidation using a zinc-substituted polyoxometalate as catalyst under homogeneous and heterogeneous (MIL-101(Cr) encapsulated) conditions by Diana Julião; Ana C. Gomes; Martyn Pillinger; Luís Cunha-Silva; Baltazar de Castro; Isabel S. Gonçalves; Salete S. Balula (78-86).
A composite material comprising the chromium terephthalate metal-organic framework MIL-101 and the tetrabutylammonium (TBA) salt of a zinc-substituted polyoxotungstate anion, TBA4.2H0.8[PW11Zn(H2O)O39] (denoted PW11Zn), has been prepared by an impregnation method and characterized by powder X-ray diffraction, scanning electron microscopy, N2 adsorption/desorption, thermogravimetric analysis, FT-IR, FT-Raman and 31P magic-angle spinning (MAS) NMR spectroscopies. The characterization data reveal that the polyoxometalate was homogeneously encapsulated within the cages of the support without affecting its crystalline structure and morphology. Both the homogeneous catalyst PW11Zn and the composite material PW11Zn@MIL-101 exhibit high activity in the extractive and catalytic oxidative desulfurization of a model oil containing dibenzothiophene, 1-benzothiophene and 4,6-dimethyldibenzothiophene. Complete desulfurization of the model oil could be achieved within 2 h by using the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate as extraction solvent, aqueous 30% H2O2 as oxidant and a reaction temperature of 50 °C. When acetonitrile was used as extraction solvent instead of the IL, the heterogeneous catalyst PW11Zn@MIL-101 could be easily recovered and reused several times without leaching or loss of activity.
Keywords: Oxidative desulfurization; Model diesel oil; Ionic liquid extraction; Polyoxometalate; MIL-101;
Co-thermal dissolution of Shenmu–Fugu subbituminous coal and sawdust by Hengfu Shui; Zhen Hui; Qingqing Jiang; Hua Zhou; Chunxiu Pan; Zhicai Wang; Zhiping Lei; Shibiao Ren; Shigang Kang (87-92).
The co-thermal dissolution (CTD) behavior of Shenmu–Fugu subbituminous coal (SFSBC) and sawdust was investigated in this study. The synergic effect between SFSBC coal and sawdust in CTD was probed. The individual thermal dissolution (TD) of SFSBC and sawdust showed that sawdust gave much higher thermal dissolution yield (TDY) and lower thermal soluble yield (TSY) than SFSBC. This resulted in much lower difference of (TDY–TSY) for SFSBC compared to that of sawdust at the same condition. CTDs of SFSBC and sawdust in 1-methylnaphthalene (1-MN) at different temperatures were carried out. The results suggested that there existed a negative synergic effect for TDY in the whole range of temperatures studied, but a positive synergic effect for TSY at 320 and 340 °C. The largest enhancements in TSY of 33.6% comparing with the corresponding calculated weighted mean values of the individual TD of SFSBC and sawdust were obtained at 320 °C. The positive synergic effect can be attributed to that the thermal depolymerization of lignin at relatively low temperatures produces lots of intermediates such as phenoxy radicals, which then attack the coal, causing scission of aliphatic carbon–carbon bonds in the coal and promoting the TD of coal.
Keywords: Co-thermal dissolution; Sawdust; Coal; Synergic effect;
Steam explosion as a fractionation step in biofuel production from microalgae by E. Lorente; X. Farriol; J. Salvadó (93-98).
In this study, various pretreatment methods (autoclaving, ultrasound, microwave and steam explosion) have been compared to determine the most efficient method for the extraction of lipids from three different samples of microalgae (Nannochloropsis gaditana, Chlorella sorokiniana and Phaeodactylum tricornutum). Among the studied methods, steam explosion gave the highest lipid extraction yields for the three microalgae species. Therefore, the method was further studied and the application of acid catalysed steam explosion pretreatment was investigated for simultaneous lipid extraction and sugar release from microalgae. The effect of different variables, including temperature and acid concentration, was analysed. The experimental results demonstrate the efficacy and feasibility of the acid catalysed steam explosion pretreatment, followed by n-hexane lipid extraction. Remarkable sugar yields up to 96% were achieved under the pretreatment conditions of 1.7% sulphuric acid concentration and a temperature of 150 °C during steam explosion. Besides, this study verified high efficiencies in the extraction of lipid of exploded microalgae using n-hexane against the low efficiencies obtained for the untreated microalgae.
Keywords: Steam explosion; Microalgae; Sugars; Oil; Biodiesel; Bioethanol;
Effects of existing energy saving and air pollution control devices on mercury removal in coal-fired power plants by Zi-Jian Zhou; Xiao-Wei Liu; Bo Zhao; Zhen-Guo Chen; Hai-Zhong Shao; Le-Le Wang; Ming-Hou Xu (99-108).
The impacts of a low temperature economizer (LTE) on mercury removal across an electrostatic precipitator and influence of load variation on mercury conversion over selective catalytic reduction (SCR) catalysts were determined at two coal-fired boilers. When the LTE was on, the total and elemental mercury removal efficiency increased by 42.87% and 18.85%, respectively, due to the improvement of adsorption and oxidation capacity of the fly ash at lower temperature. Mercury speciation at the inlet and outlet of the SCR system were analyzed, and the impacts of load variation and catalyst aging on Hg0 conversion were discussed. The variable loads resulted in simultaneous changes of the gas hourly space velocity, the ambient temperature, and the oxygen content. The results showed the load ratio was significant for Hg0 conversion by the SCR catalysts and load reduction benefitted Hg0 conversion. When the load ratios were 100%, 75% and 60%, the Hg0 conversion were 61.78%, 65.71% and 72.12%, respectively. Moreover, Hg0 conversion was more significantly affected by the catalyst aging than NOx reduction. Among the three factors, the most important one is the flue gas temperature based on the grey relational analysis.
Keywords: Coal-fired power plants; Mercury removal; ESP; Low temperature economizer; SCR catalyst; Load variation;
The influence of the pyrolysis conditions in a rotary oven on the characteristics of the products by B. Acevedo; C. Barriocanal (109-116).
The pyrolysis of 1:1 blends of reinforcing fibre (RF) from tyre wastes with low rank bituminous coal was carried out in a rotary oven. The pyrolysis conditions were modified in order to study their influence on the yield and characteristics of the char and oil obtained. The variables studied were as follows: rotation speed, final pyrolysis temperature, N2 flow and heating rate. The textural characteristics of the char were studied by means of N2 adsorption at 77 K, whereas the oil composition was studied by infrared spectroscopy and gas chromatography.Modification of the variables did not have any effect on the composition or textural properties of RF/coal char. However, an increase in the nitrogen flow, rotary speed and a decrease in the heating rate led to a higher oil yield with more oxygenated groups and less aromaticity. These conditions also caused an increase in the contribution of the light oil to the oil yield. Moreover, an increment in the final temperature also resulted in a higher percentage of light oil, a greater amount of aromatic compounds and smaller number of oxygenated groups.
Keywords: Rotary reactor; Reinforcing fibre; Coal; Tyre waste; Pyrolysis;
Catalytic decomposition of methanethiol to hydrogen sulfide over TiO2 by Takashi Mukoyama; Naohiro Shimoda; Shigeo Satokawa (117-124).
As a new desulfurization process for fuel cell systems, catalytic direct decomposition of methanethiol into hydrogen sulfide on various metal oxides without hydrogen addition has been examined. Methanethiol was decomposed into hydrogen sulfide over several metal oxide catalysts at 300 °C. Major metal oxide catalysts used in this study decomposed methanethiol completely at 500 °C. However they would be sulfurized immediately by the decomposed products. Among them, titania (TiO2) catalyst exhibited a remarkable methanethiol decomposition activity and it was hardly sulfurized. The methanethiol conversion of TiO2 catalyst depended on the specific surface area. Hydrogen sulfide and dimethyl sulfide were produced with the same amount at below 250 °C. The methanethiol seems to be decomposed by the following equation at low temperature range: 2CH3SH → H2S + (CH3)2S. In contrast, hydrogen sulfide and methane were produced as gas phase products and carbon species were also formed on TiO2 surface above 400 °C. The methanethiol seems to be decomposed by the following equation at high temperature range: 2CH3SH → 2H2S + CH4 + C. We conclude that the direct decomposition of methanethiol on TiO2 surface proceeds via different reaction pathways depending on the reaction temperatures.Display Omitted
Keywords: Desulfurization; Methanethiol; Direct decomposition; Hydrogen sulfide; Titanium oxide; Metal oxides;
Thermal characteristics and fate of heavy metals during thermal treatment of Sedum plumbizincicola, a zinc and cadmium hyperaccumulator by Dao-Xu Zhong; Zhao-Ping Zhong; Long-Hua Wu; Hui Xue; Zu-Wei Song; Yong-Ming Luo (125-132).
A horizontal tube furnace was designed to test the disposal of ground hyperaccumulator biomass. X-ray diffraction (XRD), thermodynamic analysis and chemical extraction were used to characterise the heavy metals. The recoveries of Zn, Pb, and Cd in bottom ash decreased with increasing incineration temperature but increased in fly ash. The recoveries of Zn, Pb, and Cd fluctuated with increasing air flow rate and most of the metals were found in the fly ash. Cd, Pb, and Zn occurred during the combustion process in the form of elementary substances and their oxides. During reduction in the thermal process both Pb and Cd formed metal complexes such as Ca0.75Cd0.25O and Pb2O3.333 or their mixtures and more of the bottom ash Zn under the reducing conditions was present as pure metal, crystalline oxides, sulphides or complex compounds combined with other metals.
Keywords: Hyperaccumulators; Heavy metals; Thermal disposal; Thermodynamic analysis;
Mathematical model of water sorption isotherms of UBC by Takuo Shigehisa; Toshinori Inoue; Haruo Kumagai (133-141).
Mathematical models for sorption isotherms were investigated as for UBC (Upgraded Brown Coal) and its feedstock coals, dried and not dried. Studies on classic models proved that: (1) Characteristic curves of Polanyi plot showed that UBC is more hydrophobic than its dried feedstock coal. (2) BET model is applicable in the range of 5 to 40% relative humidity and can provide a rough estimation of the heat of adsorption.Among modern models, Henderson model showed the best fitting but several other models gave satisfactory results when regression constants were properly adjusted. The fact that different models based on different theories describe a phenomenon, depending on regression constant values, implies that a reasonable interpretation of the constants is essential in understanding the phenomena through models. This is normally difficult but the constant of Henderson model was successfully interpreted through analogy to application of Weibull function to reliability engineering. Furthermore, it was proved that the constants of this model do not depend on temperature when moisture is non-dimensionalized.
Keywords: Low rank coal; UBC; Water sorption isotherms; Mathematical model; Henderson model; Weibull function;
Approach to the breakage behavior of comminuted poplar and corn stover under single impact by Miguel Gil; Ennio Luciano; Inmaculada Arauzo (142-149).
Breakage behavior under impact of two different types of biomass resources (poplar and corn stover) is characterized, taking into account the influences of the impact energy, of the number of impacts, of the input particle size and of the material properties itself. Within corn stover, two fractions showed different breakage behavior and they were analyzed separately: corn cob and corn stalk and leaves. Biomass resources present several inherent complexities such as its fibrous non-brittle behavior and the non-spherical shape of their particles. Mastercurve formulation for breakage probability (S) based on the resistance of the particles against fracture (fmat ) and on the mass specific energy which a particle can absorb without fracture (W m, min ) was obtained. Moreover, a new formulation of the new particle population generated after the impact (breakage function, B) was developed incorporating two new material parameters (γ and α) to a power law function. Corn cob showed much higher threshold energy for fracture (W m, min ) than corn stalk/leaves and poplar. Furthermore, corn cob presented the highest values of γ and α that represent coarser new particle generation. Corn stalk/leaves and poplar showed more similar material parameters in comparison to corn cob.
Keywords: Breakage; Impact; Biomass; Mastercurve; Milling;
Anaerobic digestion of C1–C4 light oxygenated organic compounds derived from the torrefaction of lignocellulosic materials by Shi-Shen Liaw; Craig Frear; Wayne Lei; Shuai Zhang; Manuel Garcia-Perez (150-158).
This paper reports the anaerobic digestion (AD) of the aqueous phase rich in C1–C4 oxygenated organic compounds derived from the torrefaction of six lignocellulosic materials (corn stover, annual rye straw pellet, pea hay, sorghum biomass, arundo donax and red fir wood) in an Auger reactor. The content of some of the most important C1–C4 compositions found in the aqueous phase measured by GC/MS is reported. Some of the compounds identified in the torrefaction aqueous phase produced (acetic acid, acetol, hydroxyacetaldehyde and phenol 2-methoxy) were anaerobically digested. The optimal concentration at which acetol and acetic acid could be digested was 1.5 and 1 mass % respectively. Much lower optimal concentrations were obtained for hydroxyacetaldehyde (HAA) and phenol 2-methoxy (0.01 mass %) which were found to be the main inhibitors. At 200 h and at the optimal concentration obtained for acetic acid, acetol, HAA and phenol-2 methoxy the yield of biogas produced was 363, 50, 600 and 4100 ml/g respectively. The AD of the aqueous phase obtained from the torrefaction of the six biomasses studied was conducted at the same conditions used for the model compounds. The optimal concentration these aqueous phases could be digested was: 2.5, 1.5, 1.5, 1.5, 0.5 and 0.5 mass % for the pea hay, corn stover, arundo donax, annual rye, sorghum biomass and red fir wood respectively. At 500 h and the optimal concentrations the yield of bio-gas produced was 106, 85, 91, 53, 32 and 88 ml/g of aqueous phase for pea hay, corn stover, arundo donax, annual rye straw, sorghum biomass and red fir wood respectively. A linear correlation was obtained between the optimal concentration at which a torrefaction aqueous phase can be AD and the content of HAA + phenols.
Keywords: Thermo-chemical conversion; Anaerobic digestion; Torrefaction;
Co-processing raw bio-oil and gasoil in an FCC Unit by Andrea de Rezende Pinho; Marlon B.B. de Almeida; Fabio Leal Mendes; Vitor Loureiro Ximenes; Luiz Carlos Casavechia (159-166).
Bio-oil is a complex blend of oxygenated compounds, such as acetic acid, hydroxyacetone and phenols, and is produced from the fast pyrolysis of raw biomass. A raw bio-oil produced from pine woodchips was co-processed with standard gasoil and tested in a 150 kg/h fluid catalytic cracking (FCC) demonstration-scale unit. The bio-oil was cracked into valuable products, such as gasoline and LCO, with similar product yields obtained from the base FCC feed when up to 10% bio-oil was used. However, some deterioration was observed when 20% bio-oil was added. 14C isotopic analyses were performed to determine the renewable carbon content in the FCC liquid products. When 20% bio-oil was co-processed, the renewable carbon content in the gasoline cuts varied between 3% and 5%. For 10% bio-oil in the feed, 2% renewable carbon was obtained in the total liquid product. Large amounts of phenolic compounds were detected in the naphtha produced by the FCC. The FCC carbon efficiency, which is defined as the amount of carbon in bio-oil converted to carbon in the total liquid products, was approximately 30%, well above the values found in the literature for FCC bio-oil upgrading (15%–20%) when using laboratory scale units.
Keywords: Refining; Co-processing; Fluid catalytic cracking; Biofuels; Bio-oil;
Effect of additives on the microwave-assisted pyrolysis of sawdust by Hui Shang; Ran-Ran Lu; Liang Shang; Wen-Hui Zhang (167-174).
The pyrolysis of biomass was conducted using a microwave heating system operated at 2.45 GHz. Additives, such as silica carbon, activated carbon, coke produced through microwave-assisted pyrolysis, potassium carbonate, and sodium hydrate, were investigated for their effects on the sawdust pyrolysis. It was found that additives had significant effects on the yields and properties of the final products. By employing silica carbon, the gas and liquid yields were relatively low, due to the non-uniform mixing caused by big density difference between the sawdust and silica carbon particles. However, with potassium carbonate and sodium hydrate, the pyrolysis products are mainly gases, since both additives can absorb microwave strongly, making extremely high temperature inside the sawdust. The liquid products were analyzed by electrospray FT–ICR MS. Potassium carbonate can simplify the bio-oil composition and reduce compound types, which is beneficial to its further applications. The pyrolysis is highly influenced by heating rate and a first order was found for the reaction. Additives under microwave irradiation would enhance the heating rate, while they mainly act as catalysts instead of enhanced heating.
Keywords: Microwave heating; Pyrolysis; Biomass; Bio-oil;
Molecular composition of water-soluble lignins separated from different non-food biomasses by Davide Savy; Antonio Nebbioso; Pierluigi Mazzei; Marios Drosos; Alessandro Piccolo (175-181).
Separation of water-soluble lignins from lignocellulosic biomass provides a new and still poorly exploited feedstock to increase the sustainability of biorefineries. We applied derivatization followed by a reductive cleavage (DFRC) method, 2D-HSQC-NMR, and 31PNMR after 31P-labeling, to investigate molecular composition in water-soluble lignins obtained by alkaline oxidation from three biomass materials for energy (miscanthus, giant reed and an industrially pre-treated giant reed). Chromatographic identification of lignin products cleaved by DFRC showed a large predominance of guaiacyl (G) units in all biomasses and a lesser abundance of syringyl (S) and p-coumaryl (P) monomers. Our S/G ratios disagree with those reported in literature by other lignin separation methods. Carboxyl functions (ferulic and pcoumaric acids) were revealed by heterocorrelated 1H–13C HSQC-NMR, and confirmed by 31P-NMR spectra of 31 P-labeled lignin molecules. An understanding of molecular composition of water-soluble lignins from biomass sources for energy is essential for lignin most efficient exploitation in either industrial or agricultural applications.Display Omitted
Keywords: Lignin; Alkaline hydrogen peroxide; Giant reed; Miscanthus; DFRC; 1H–13C HSQC-NMR; 31P-NMR;
Emission of carbon monoxide, total hydrocarbons and particulate matter during wood combustion in a stove operating under distinct conditions by E.D. Vicente; M.A. Duarte; A.I. Calvo; T.F. Nunes; L. Tarelho; C.A. Alves (182-192).
Wood combustion experiments were carried out to determine the effect of ignition technique, biomass load and cleavage, as well as secondary air supply, on carbon monoxide (CO), total hydrocarbon (THC), particulate matter (PM10) and particle number emissions from a woodstove. Wood from two typical tree species in the Iberian Peninsula was selected: pine (Pinus pinaster) and beech (Fagus sylvatica). The highest CO and total hydrocarbon emission factors (EFs) were observed, respectively, for pine and beech, for high and low fuel loads. The highest PM10 EF was recorded for the operation with low loads for both woods. Secondary air supply produced the lowest PM10 emission factors. The top ignition can decrease the PM10 EF to less than half when compared with the common technique of lighting from the bottom. The lowest particle number emission factors were observed when operating with high loads of split beech logs and when using secondary air supply during the combustion of pine. Regarding particle number distributions, the highest geometric mean diameter (Dg), for both woods, were observed when operating with high loads (with split and non-split wood).
Keywords: Woodstove; Operating conditions; CO; PM10; Particle size distribution; Emission factors;
Evaluation of microwave treatment on coal structure and sulfur species by reductive pyrolysis-mass spectrometry method by Sh. Mesroghli; J. Yperman; E. Jorjani; R. Carleer; M. Noaparast (193-202).
A comparative study of the effect of microwave irradiation on the determination of organic sulfur forms in high sulfur coal samples of Tabas coal was studied by atmospheric pressure-temperature-programmed reduction (AP-TPR) method coupled on-line with MS. This analytical technique demonstrates the direct effect of microwave irradiation on coal matrix and on sulfur compounds, qualitatively and quantitatively. For the evaluation of the impact of microwave irradiation on sulfur compounds m/z 34 (H2S+) is monitored and on coal matrix the aromatic (benzene m/z = 77 (C6H5+), m/z = 78 (C6H6 +), toluene m/z = 92 (C7H8 +), m/z = 91 (C7H7 +) and xylene m/z = 91 (C7H7 +)) and aliphatic fragments ((m/z = 39 (C3H3 +), 41 (C3H5 +), 43 (C3H7 +), and 55 (C4H7 +)) are considered. Aromatic sulfur compound structures are more altered than aliphatic ones, as is demonstrated by its evolved H2S peak area and temperature changes. A great peak maximum shift of all aromatic fragments towards higher temperature was noticed, due to the poly cyclic aromatic ring formation as a result of microwave treatment. The microwave treatment used on the coal samples, resulted in coal matrix degradation and changes in terms of physical characteristics and causing a simultaneous degradation of the organic matrix.
Keywords: Coal; Sulfur; Mass spectrometry; Reductive pyrolysis; Microwave irradiation;
Biomass gasification: Influence of torrefaction on syngas production and tar formation by Marek Dudyński; Johan C. van Dyk; Kamil Kwiatkowski; Marta Sosnowska (203-212).
The paper contains results of comparative gasification of standard wood biomass pellets, torrefied pellets and sawdust in a robust industrial fixed-bed gasifier. Parameters such as process stability, operating difficulties, gas parameters and tar content in syngas were analysed. The operating conditions were optimised to maximise production of liquid hydrocarbons, which can be both a problematic by-product and a valuable component. In order to collect the data concerning quantity and composition of the tars, the experimental set-up was equipped with a syngas cooler.The test runs conducted with sawdust and ordinary pellets did not cause any operational problems. The most complicated part of the experiment was maintaining process stability during gasification of torrefied pellets. The stabilisation effect of grinding of torrefied pellets and blending these pellets with wet sawdust were tested. It was concluded that effective and stable gasification of torrefied pellets in the tested type of fixed-bed gasifier is possible, but this type of fuel is much more suitable for co-gasification.The cleaned syngas from standard pellets had a relatively stable composition and calorific values in the range of 4.8–5.6 MJ/Nm3. Cold gas efficiencies of the process were in the range of 0.72–0.77 MJ/Nm3. Using torrefied pellets as a feedstock led to a higher calorific value of syngas, but the cold gas efficiency remained similar (0.75). For sawdust both the calorific value of syngas (LHV = 3.0 MJ/Nm3) and cold gas efficiency (0.57) were significantly lower than for pellets. The collected condensates contained a water fraction with dissolved organic compounds and thick viscous organic substances tar. It was observed that tar production from torrefied pellets is slower, characterised by lower yield, and technically more difficult in comparison to untreated biomass. The effectiveness of liquid hydrocarbon collection (tar to fuel ratio) varied between 0.0138 [kg tar/kg fuel] for torrefied pellets and 0.0213 [kg/kg] for sawdust. The main component of water fractions were organic acids. The content of organic acids in these fractions was as follows: 79.5% from South African pellets, 67% from Polish pellets, 64% from Polish sawdust and 59% from torrefied pellets respectively. The main organic species in tar from torrefied biomass remained acids, whereas in other cases tars were composed of alkylophenols, linear and cyclic aliphatic oxygenates and polyfunctional aromatic oxygenates.
Keywords: Biomass; Gasification; Torrefaction; Tar; Syngas;
Experimental study on diesel fuel injection characteristics under cold start conditions with single and split injection strategies by Ziman Wang; Haichun Ding; Miroslaw L. Wyszynski; Jianyi Tian; Hongming Xu (213-222).
Studies on fuel flow characteristics under both room temperature (25 °C) and low temperature (− 18 °C) were carried out under a wide range of injection pressures and back pressures using a long tube real-time fuel flow rate measuring instrument. Both single and split injection strategies were employed. Several modified correlations were proposed to analyze fuel injection characteristics. It was found that low fuel temperature caused longer injection delay, shorter injection duration, lower mass flow rate and less injected fuel mass. The injector discharge coefficient was affected more by fuel viscosity changes due to low temperature than by the geometric structure of the injector. Cold start conditions effectively limited the inception of cavitation as seen in the flow rate/pressure dependence and accelerated the transition of flow regime from cavitation to turbulent and laminar flow with the decrease of injection pressure. This contributed to increased chances for the existence of laminar flow and thus to reduction of the discharge coefficient. Besides, low fuel temperature significantly weakened the degree of interaction between individual parts of split injection and split mass flow rate shapes became much less continuous than those under room temperature. These findings are of great importance for engine cold start studies.
Keywords: Fuel injection characteristics; Low temperature; Flow regime; Split injection strategy;
Predicting the vapor pressure of fatty acid esters in biodiesel by group contribution method by Tian-You Wang; Xiang-Zan Meng; Ming Jia; Xiao-Chao Song (223-229).
In this study, a group contribution method based on the Riedel equation was developed to predict the vapor pressures of fatty acid methyl, ethyl, propyl, and butyl esters. A CH2 (ester) group was introduced to distinguish the fatty acid methyl, ethyl, propyl, and butyl esters. The group parameters were regressed based on a total of 4687 vapor pressure data. The results show that, the proposed group contribution method illustrates much better performance in predicting the vapor pressures of fatty acid methyl and ethyl esters, and comparable accuracy in predicting the vapor pressures of fatty acid propyl and butyl esters in comparison with Ceriani's group contribution method (Ceriani et al., 2013). A test set of 2584 experimental data was used to further verify the reliability of the proposed method and its superiority in accurately predicting the vapor pressure within the whole temperature range over Ceriani's group contribution method. By using these two group contribution methods, vapor pressures of ten biodiesels were also predicted, and the proposed group contribution method has a better accuracy with the overall average relative deviation of 5.49%. The temperature dependency of biodiesel vapor pressure is also well reproduced by the proposed method.Display Omitted
Keywords: Biodiesel; Vapor pressure; Prediction; Group contribution;
Determination of naphtha composition by near infrared spectroscopy and multivariate regression to control steam cracker processes by Vitor Hugo da Silva; Marcio V. Reboucas; Alan Rocha Salles; Maria Fernanda Pimentel; Márcio José Coelho Pontes; Celio Pasquini (230-237).
Naphtha is an important feedstock for the petrochemical industry and accurate measurement of its detailed composition is essential for the optimization of pyrolysis processes. In the present work, the suitability of using near infrared (NIR) for the determination of 38 parameters used to characterize naphtha was evaluated: pooled composition (PIONA); specific composition groups (C3 paraffins; C4–C12 n-paraffins; C4–C12 iso-paraffins; C5–C7 + naphthenics; C8–C10 aromatics; C4–C6 olefins) and individual components (toluene, benzene, iso-pentane, cyclopentane, methyl cyclopentane; cyclohexane, xylenes, 1,3 butadiene and isoprene). Besides the usual comparison against reference methods, NIR predictions were also evaluated for their ultimate use in determining the coil outlet temperature (COT) for process control. 28 models for the naphtha parameters presented root mean square error (RMSEP) values lower or close to the reproducibility of the reference method and exhibited satisfactory correlation values (r 2) when compared with r 2 max. Among the ten remaining parameters, two (1,3 butadiene and isoprene) presented very low concentrations and it was not possible to obtain a suitable model. Eight parameters had RMSEP values higher than the intralaboratory reproducibility and/or r 2 values lower than expected. Despite this, the complete naphtha composition obtained from NIR prediction was demonstrated to be quite suitable for COT simulation, providing accurate COT values compared to the values estimated from the reference method.
Keywords: Naphtha; NIR; Pyrolysis; Multivariate calibration; Steam cracker; COT;
Properties of a manganese oxide octahedral molecular sieve (OMS-2) for adsorptive desulfurization of fuel gas for fuel cell applications by Phuoc Hoang Ho; Seong Chan Lee; Jieun Kim; Doohwan Lee; Hee Chul Woo (238-246).
Properties and characteristics of cryptomelane manganese oxide octahedral molecular sieve (OMS-2)-based adsorbents for the adsorptive desulfurization of dimethyl sulfide (DMS), tert-butylmercaptan (TBM), and tetrahydrothiophene (THT) were investigated at ambient temperature and atmospheric pressure. OMS-2 adsorbents exhibited above 90% adsorption selectivity for TBM in a ternary mixture of DMS, TBM, and THT in a methane fuel stream, which is unique and unprecedented for zeolite-, metal oxide-, and activated carbon-based adsorbents. Hetero-metal doped M-OMS-2 (M = Ag, Ce, Co, Cu, Fe, La, Ni, Zn) adsorbents were prepared, and the effects of doped metal entities for TBM adsorption were studied. In particular, Cu-OMS-2 exhibited substantially enhanced TBM adsorption uptakes that were greater than 2.6 times that of the pristine OMS-2. A high TBM adsorption of 4.44 mmol S g− 1 was achieved on Cu-OMS-2 (2.5 wt.% Cu doping), 2–7 times greater than the values reported for zeolite- and activated carbon-based adsorbents at similar experimental conditions. Structure and properties of OMS-2-based adsorbents were studied at various synthesis conditions and characterized with SEM, TEM, XRD, TGA, elemental analysis, N2 adsorption, and temperature programmed desorption (TPD) methods. The selective adsorption and thermal regeneration characteristics of OMS-2 were rationalized with a proposed mechanism. Thermal regeneration led to deactivation of OMS-2 due to a poisoning of adsorption sites by residual sulfur species and an alteration of the crystalline structure by reduction, in the case of thermal regeneration in an inert atmosphere, accompanying some collapse of the accessible pore structures.Display Omitted
Keywords: Desulfurization; Manganese oxide octahedral molecular sieve; Fuel processing; tert-Butylmercaptan; Fuel cell;
Catalytic performances of Ni–CaO–mayenite in CO2 sorption enhanced steam methane reforming by Moisés R. Cesário; Braúlio S. Barros; Claire Courson; Dulce M.A. Melo; Alain Kiennemann (247-253).
Ni–CaO–mayenite (Ca12Al14O33) catalysts for the CO2 Sorption Enhanced Steam Methane Reforming (SE-SMR) have been developed using the microwave assisted self-combustion method of preparation. The sorption of CO2 by CaO shifts the steam reforming and the Water Gas Shift reaction (WGS) towards H2 production and favors the heat balance of the global reaction.The CO2 sorption has been studied on materials with different CaO/Ca12Al14O33 ratios and for different types of preparation. The specific surface area of materials, the temperature of Ni phases' reducibility and CO2 sorption are all essential for material efficiency. The Ni–CA75MM catalyst was the most active and stable in methane steam reforming with CO2 sorption, even at an unusually low temperature (650 °C).Display Omitted
Keywords: Steam methane reforming; CO2 sorption; Microwave assisted self-combustion method; Hydrogen;
Mercury speciation in liquid petroleum products: Comparison between on-site approach and lab measurement using size exclusion chromatography with high resolution inductively coupled plasma mass spectrometric detection (SEC-ICP-HR MS) by Florine Gaulier; Alexandre Gibert; David Walls; Michael Langford; Stuart Baker; Arnaud Baudot; Fabien Porcheron; Charles-Philippe Lienemann (254-261).
The accuracy of two different analytical methods dedicated to the speciation of mercury in liquid hydrocarbons is discussed in the present paper. A first step involving the comparison of a modified UOP 938 method—based on filtration, purge and extraction—with size exclusion chromatography coupled to ICP-HR MS (SEC-ICP-HR MS) was carried out on specific synthetic model mercury compounds. The modified UOP 938 method (defined here as operational speciation) allowed various mercury compounds to be grouped into different families, i.e. particulate, volatile, ionic and organic non-ionic mercury, whereas SEC-ICP-HR MS provided size distribution profiles of mercury-containing molecules. In a second step, comparison of the two different approaches was then performed with real hydrocarbon feeds, such as crude oil, condensate and straight-run gasoline samples. It was demonstrated that even though elemental Hg was present for the North Sea condensate, all of them contained ionic Hg associated to molecules containing few to many tens of carbon atoms.
Keywords: Mercury; Hg speciation; ICP/MS; Hg; Liquid petroleum; Size exclusion chromatography;
Sulfur K-edge XANES study of sulfur transformation during pyrolysis of four coals with different ranks by Meijun Wang; Lijuan Liu; Jiancheng Wang; Liping Chang; Hui Wang; Yongfeng Hu (262-269).
Sulfur transformations during pyrolysis of four high sulfur coals with different ranks are studied by measuring the release of S-containing gaseous products using online gas chromatography with a flame photometric detector and analyzing the sulfur forms in raw coals and chars using sulfur K-edge X-ray absorption spectroscopy. Results show that the sulfur forms in different coals are different and they behave differently during pyrolysis. More active disulfide and sulfide in lower rank coal can be decomposed and released as gas products below 500 °C; while a more complex thiophenic structure in the higher rank coal is difficult to decompose even at 1000 °C. Decomposition of pyrite in coal plays an important role in sulfur transformation during pyrolysis of coals rich in pyritic-sulfur. Pyrite begins to convert to FeS above 300 °C; while FeS will also react with nascent char or volatiles above 600 °C. The inter-conversions among sulfur species in solid play a dominant role in the transformation of sulfur forms above 600 °C. The minerals in coal are valuable in understanding conversions of sulfate and sulfide. The sulfur retention in solid form is correlated well with the releasing trend of H2S and COS during the coal pyrolysis.
Keywords: High sulfur coal; Pyrolysis; Sulfur form; Release; Inter-conversion; X-ray absorption spectroscopy;
A review of pyrolysis, aquathermolysis, and oxidation of Athabasca bitumen by Punitkumar R. Kapadia; Michael S. Kallos; Ian D. Gates (270-289).
The recovery of heavy oil and oil sand deposits of western Canada by using in situ combustion or gasification recovery processes has always been a great technological and economical challenge. During in situ combustion bitumen recovery processes, pyrolysis, aquathermolysis and oxidation mechanisms coexist because of co-existence of bitumen, water and oxygen in the presence of high temperature and high pressure. The modeling of such processes requires comprehensive reaction schemes along with kinetic parameters to describe each of these mechanisms. The determination of such kinetic parameters requires extensive lab and/or pilot studies due to the complex chemical nature of bitumen. During these studies, it is customary to represent bitumen and products of bitumen combustion by pseudo-components to describe the bitumen combustion reaction scheme in a way which not only describes the process reasonably well but also is easy to understand. Although there have been numerous bitumen combustion experiments conducted over the past 80 + years, all of the data and experience have not been analyzed comprehensively with a focus towards integrating all of the evidence into a single vision of the process. Here, we review all previously published lab scale and pilot experimental data, various reaction schemes and field observations published for pyrolysis, aquathermolysis, oxidation, and/or gasification of Athabasca bitumen. These studies were conducted either to understand the chemical structure of bitumen or to develop reaction schemes for use in numerical simulators. This review reveals a new overall vision for combustion processes for in situ bitumen recovery and also shows that there are key data sets not currently available that would greatly enhance modeling and simulation work needed for the full recovery of Athabasca bitumen resources.
Keywords: Athabasca bitumen; Pyrolysis; Aquathermolysis; Oxidation; Gasification; Combustion;
Preparation of biodiesel from soybean oil using La/Mn oxide catalyst by Sadia Nasreen; Hui Liu; Dejan Skala; Amir Waseem; Liang Wan (290-296).
The solid catalyst La/Mn oxide was prepared using co-precipitation method. The catalytic behavior for catalyzing transesterification of soybean oil with methanol under subcritical conditions was investigated in a batch reactor; optimization of several parameters for catalyst preparation and transesterification reaction was also performed. The triglyceride (TG) conversion of above 99% was obtained using La/Mn oxide catalyst prepared with La:Mn molar ratio of 2:1 and calcined at 600 °C for 90 min, under such reaction conditions as 3 wt.% of catalyst, methanol/oil molar ratio of 12:1, reaction temperature and time of 180 °C and 60 min, respectively. The catalyst shows good reusability, and can resist FFA to some extent. However, it is sensitive to water. The mechanisms of catalytic activity and deactivation were discussed according to the characterization of the fresh and used catalysts using basic strength, BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), and X-ray diffraction (XRD). Results demonstrated that the complex oxide LaMnO3.15 was the dominant component. The crystalline structure of the catalyst after use changed remarkably and the active sites might be occupied by organics, which led to the deactivation or diminished activity of the catalyst in the repeated use process.Display Omitted
Keywords: Biodiesel; Solid base catalyst; Transesterification; La; Mn;
Investigation of grape marc combustion using thermogravimetric analysis. Kinetic modeling using an extended independent parallel reaction (EIPR) by Maximilien Valente; Alain Brillard; Cornelius Schönnenbeck; Jean-François Brilhac (297-303).
The increasing demand for renewable energies leads to a necessary diversification of combustibles among which are biomasses. The present study focuses on the kinetic analysis of grape marc as a new potential resource. The pyrolysis and the combustion of wine residues are first studied from an experimental point of view, through a thermogravimetry analysis. An extended IPR model based on a biomass lignocellulosic representation is then proposed which is proved to simulate with a great accordance the thermal decomposition of grape marc considering both devolatilization and char combustion. The resolution of the equations of this model and the determination of the optimal set of kinetic constants are performed using a numerical procedure based on Scilab routines. Different heating rates have been considered and their influence on the decomposition of the grape residues is examined.
Keywords: Grape marc; Pyrolysis; Combustion; Thermogravimetric analysis; Extended IPR model; Kinetic constants;
Transformations of pyrite in different associations during pyrolysis of coal by Hui-Ling Zhao; Zong-Qing Bai; Jing-Chong Yan; Jin Bai; Wen Li (304-310).
The samples of pure pyrite, the mixtures of FeS2 or FeS loaded on a low-ash coal char, and an acid-washed coal with high content of pyrite were used to investigate the transformations of pyrite with different physical associations during pyrolysis. The presence of low-ash coal char, although affected the evolution of sulfur-containing gases in vapor phase, had little influence on thermal decomposition of pyrite at 450–650 °C. Pyrite conversion above 920 °C, especially transformation of the formed FeS into elemental iron, was facilitated primarily by the char matrix entity. During pyrolysis of coal, isolated agglomerates of single pyrite crystals were transformed into individual aggregates in the gaps of coke grains, while most of pyrite embedded in the coal particles or located at the edge of coal particles decomposed to the Fe–S phases which remain inside or closely in contact with the carbon matrix. Meanwhile low-sulfur Fe–S phases in the pyrolysis products of coal were mainly represented as FeSy (0 < y < 1).Display Omitted
Keywords: Pyrolysis; Pyrite; Gaseous sulfur-containing species; Coal;
Hydroisomerization of n-heptane over MoP/Hβ catalyst doped with metal additive by Ping Liu; Meng-Yao Wu; Jun Wang; Wei-Hong Zhang; Yong-Xin Li (311-316).
The bifunctional catalysts of molybdenum phosphide supported on Hβ zeolite (MoP/Hβ) were prepared using a co-impregnation–temperature-programmed reduction method, and catalytically tested in the hydroisomerization of n-heptane. The catalytic conversion and isomerization selectivity of MoP/Hβ were revealed to be higher than those of the control tungsten phosphide sample WP/Hβ and the HMCM22-supported counterpart MoP/HMCM22. Moreover, doping Cr, Ni, or Ce significantly improved the activity of MoP/Hβ; meanwhile, the Cr-promoted catalyst also gave an enhanced selectivity to isomerization products. The catalysts were characterized by X-ray diffraction, Brunauer–Emmett–Teller analysis, temperature-programmed desorption of NH3, and temperature-programmed reduction of H2. Accordingly, it is suggested that the promoting effect of the secondary metal additive is relative to the reduction of MoPO x species, as well as the pores and acid sites of the β zeolite.Display Omitted
Keywords: Molybdenum phosphide; Hydroisomerization of n-heptane; Bifunctional catalysts;
Dry separation on coal–silica mixture using rotary triboelectrostatic separator by Jinxiang Chen; Rick Honaker (317-324).
Silica minerals are one of the major contaminants in coal. They significantly deteriorate the coal quality and need to be removed before the use of coal. Conventional coal preparation techniques are wet processing methods that require huge quantities of water and chemical reagents, which induce high operation cost and environmental pollution. Therefore, dry separation technique to preconcentrate coal before the wet processing or even substitute the wet processing is required. In this study, the coal–silica mixture was beneficiated using a novel rotary triboelectrostatic separator (RTS). This new type of electrostatic separator is characterized with high particle charging efficiency, good separation environment and high throughput. The experiment result shows the surface charge densities of the coal, and the silica particles are greatly enhanced and the ash rejection of coal–silica mixture is achieved using the RTS. The ideal coal–silica mixture electrostatic separation characteristic using the RTS was determined. The charge density difference between coal and silica particles is distinct after the charging process. Better separation efficiency could be obtained when an industrial size RTS is available to use.
Keywords: Dry separation; Rotary triboelectrostatic separator; Silica; Coal;
One-pot production of hydrocarbons from xylitol by hydroiodic acid reduction by Dong-Can Lv; Yun-Quan Liu; Shui-Rong Li; Yue-Yuan Ye; Duo Wang (325-329).
In this work, direct production of heavier hydrocarbons from biomass-derived xylitol by reduction with hydroiodic acid (HI) in the presence of phosphorous acid (H3PO3) was studied. The effects of the feed ratio of raw materials, mixing intensity, and reaction time on catalytic performance were investigated by experiments. It was found that the molar ratio of xylitol/HI and H2O/HI had significant effects on the conversion of xylitol and yield of hydrocarbons. A maximum yield of 80.3% for hydrocarbons was achieved at a xylitol/HI/H3PO3/H2O molar ratio of 0.4:1:2:12, a mixing intensity of 800 rpm, and a reaction time of 12 h. High performance liquid chromatography (HPLC) and gas chromatograph/mass spectrometer (GC/MS) were used to determine the amount of xylitol and to analyze the composition of hydrocarbon products, respectively. The hydrocarbons obtained are mainly C10 and C15 hydrocarbons with aromatic rings, which have a high heating value of 43 kJ/g, making them suitable for diesel or/and jet fuel substitutes.Display Omitted
Keywords: Biomass; Xylitol; Reduction; Hydroiodic acid; Hydrocarbons;
Effect of temperature on the enrichment and volatility of 18 elements during pyrolysis of biomass, coal, and tires by Helena Raclavská; Agnieszka Corsaro; Dagmar Juchelková; Veronika Sassmanová; Jaroslav Frantík (330-337).
The effect of temperature on the enrichment and volatility of elements during pyrolysis of brown coal, biomass pellets, and used tires was evaluated. The elements investigated included barium (Ba), bromine (Br), calcium (Ca), chlorine (Cl), chromium (Cr), copper (Cu), iron (Fe), potassium (K), manganese (Mn), phosphorus (P), lead (Pb), rubidium (Rb), sulfur (S), silicon (Si), strontium (Sr), titanium (Ti), yttrium (Y), and zinc (Zn). The pyrolysis experiments were conducted in a semi-continuously operated triple-screw reactor at four temperatures: 500, 550, 600, and 650 °C. An enhancement in the total contents of elements was observed in all materials due to pyrolysis. The highest enrichment of elements was observed in char from pyrolysis of coal, followed by biochar, and char from pyrolysis of tires. Differences between investigated materials were also observed regarding volatility of elements and they were attributed primarily to (i) discrepancies in the composition of raw materials, (ii) secondary reactions of chars, and (iii) the affinity and occurrence of elements.
Keywords: Pyrolysis; Enrichment; Volatility; Biomass; Coal; Tires;
Defluidization and agglomeration of a fluidized bed reactor during Cynara cardunculus L. gasification using sepiolite as a bed material by D. Serrano; S. Sánchez-Delgado; C. Sobrino; C. Marugán-Cruz (338-347).
This work studies the defluidization time and the agglomerate generation in a bubbling fluidized bed (BFB) reactor during Cynara cardunculus L. gasification using, separately, two different bed materials, silica sand and sepiolite (Mg8Si12O30(OH)4(OH2)48H2). The high adsorption capacity and the elemental composition of the sepiolite make it suitable as an alternative bed material in order to reduce agglomeration. Experiments were performed on a stainless steel lab-scale BFB reactor operating with air as a gasifying agent at different air excess ratios (u/umf). A quartz reactor was alternatively used for the visualization of bed material and biomass during gasification, allowing one to observe the agglomerate formation process. Pressure signals were analyzed both in time and frequency domain to determine the defluidization time. Furthermore, the shape and size of the bed material after the experiments were evaluated. Higher defluidization times in the case of sepiolite were measured. Particle sizes were affected by the type of bed material and the air excess and agglomerates of different shapes were formed for sepiolite and silica sand.
Keywords: Biomass; Gasification; Fluidized bed; Sepiolite; Agglomeration; Defluidization;
Modification of lignite ash fusion temperatures by the addition of different types of sewage sludge by M.B. Folgueras; M. Alonso; J.R. Folgueras (348-355).
The effect of the addition of three types of sludge (A, V and F) on the slagging behaviour of a brown lignite was investigated. It was evaluated by determining ash fusion temperatures (AFTs) of lignite, sludge samples and coal-sludge blends of 10 and 50 wt.% of each sludge, together with their chemical and mineral composition. The addition of sludge to lignite produces a decrease in the AFTs, the extent of which depends on the percentage of sludge added to the lignite, as well as the sludge additives used (organic polyelectrolyte, lime and/or FeCl3) and their phosphorus content. As a consequence, the addition of sludge to lignite produces an increase in the slagging tendency. Those lignite–sludge blend ashes whose base to acid ratio (B/A(+ P)) ranges from 0.7 to 2.0 have the lowest AFTs. In this range, most of the ash compositions are near to those of SiO2–Al2O3–CaO eutectics. Also, an increase in the phosphorus content of the blends, as well as the formation of amorphous silicates and phosphates, reduce the AFTs.
Keywords: Lignite; Sewage sludge; Ash fusibility; Sludge additives; Phosphorus;
An experimental investigation on the drying kinetics of a single coarse particle of Belchatow lignite in an atmospheric superheated steam condition by Yosuke Komatsu; Anna Sciazko; Marcin Zakrzewski; Shinji Kimijima; Akira Hashimoto; Shozo Kaneko; Janusz S. Szmyd (356-369).
The efficiency of lignite-fired power plants is sacrificed by the high moisture content of this energy carrier. The most adequate effort for upgrading the potential of lignite is the drying process, influenced by both the drying conditions and the physicochemical features of lignite. This paper presents studies on the drying kinetic of the Belchatow lignite originating from the biggest Polish lignite mine. Experimental attempts were conducted for spherical lignite samples dried in a superheated steam atmosphere at the temperature range of 110–170 °C. Each experiment includes the simultaneous measurements of changes in weight and temperature profiles for a single sample. Additionally, the drying process was recorded to observe the cracking on the surface of the sample and its shrinkage. The kinetics were described in the form of moisture content, drying rate and temperature profiles over the drying process. The time and rate of the superheated steam drying process depending on the sample size and steam temperature were estimated. Those parameters are essential for the design of an effective industrial coal drying system, which allows for the latent heat recovery of water evaporation from the lignite, which in turn will improve the thermal efficiency of the lignite-fired power generation.Display Omitted
Keywords: Low-rank coal; Lignite; Brown coal; Upgrading lignite quality; Drying characteristics; Drying process in atmospheric superheated steam condition;
Dielectric characterization of corn stover for microwave processing technology by F. Motasemi; Arshad Adam Salema; Muhammad T. Afzal (370-375).
The aim of this paper was to investigate the microwave dielectric properties of corn stover at 915 and 2450 MHz from room temperature to 700 °C under nitrogen (N2) environment. Cavity perturbation method was used to measure the dielectric constant and loss factor. The heating process was divided into three distinct stages, namely drying, pyrolysis, and char stage. Dielectric properties during drying and pyrolysis stages were inversely proportional to the temperature, whereas directly proportional to the temperature in char stage. The maximum microwave penetration depth of 8.5 m was obtained at 392 °C and 915 MHz, just at the end of the pyrolysis reaction zone. The experimental data were fitted using regression fit and based on this the dielectric properties model related to the temperature was developed.Display Omitted
Keywords: Microwave; Dielectric properties; Pyrolysis; Corn stover; Char; Modeling;
A highly active Ni/mesoporous attapulgite for hydrocracking C―O bonds in rice straw by Xiang Li; Zhi-Min Zong; Wei-Wei Ma; Zhe-Hao Wei; Yan Li; Jing-Pei Cao; Mohannad Mayyas; Zhan-Ku Li; Xian-Yong Wei (376-381).
A novel linear core–shell structured mesoporous silica coated microfiber attapulgite (MPSCMFA) was prepared. Ni/MPSCMFA, i.e., MPSCMFA-supported nickel catalyst was subsequently prepared by thermally decomposing nickel tetracarbonyl on MPSCMFA. Benzyloxybenzene (BOB) was used as a related model compound to evaluate the catalytic activity of Ni/MPSCMFA for C―O bond cleavage. As a result, BOB was completely converted to toluene and phenol under pressurized hydrogen at 150 °C over Ni/MPSCMFA, suggesting that Ni/MPSCMFA is highly active for hydrocracking the C―O bond in BOB at low temperatures. Ni/MPSCMFA-catalyzed hydroconversion of rice straw powder (RSP) was also investigated. The results show that the resulting soluble portion (SP) has higher contents of carbon and hydrogen, but lower content of oxygen than RSP. Especially, C4–C9 alkanols are the dominant compounds in the SP (up to 70.77%).
Keywords: Nickel; Mesoporous attapulgite; Hydroconversion; Benzyloxybenzene; Rice straw;
Cyclone fly ash from a grate-fired biomass combustion plant: Dependence of the concentration of various components on the particle size by Christof Lanzerstorfer (382-388).
In this study cyclone fly ash from a grate-fired combustion plant using forest residues as fuel was split into particle size classes with mass median diameters of 2.0 μm, 4.3 μm, 9.1 μm, 18 μm and 43 μm by use of an air classifier. The particle classes were analysed for total carbon, Na, K, Mg, Ca, Sr, Ba, Ti, V, Cr, Mo, Mn, Fe, Si, Co, Ni, Cu, Zn, Cd, Hg, B, Al, Pb, As, Sb, Bi, Cl−, NO3 −, PO4 3 − and SO4 2 − and the size dependence of the concentrations c was modelled using the relation c ~ 1/dN. For several components a considerable dependence of the concentration on the particle size was observed. Increasing concentration with decreasing particle size was found for K, Bi, Cd, Cu, Hg, Pb, Zn and for Cl−, NO3 − and SO4 2 −. The metals Al, As, Ba, Fe, Si, Ti and V showed the opposite behaviour. Other components, including TC, Ca, Mg, PO4 3 −, Na and Mn showed no size-dependence. Investigation of single particles by scanning electron microscope in combination with energy-dispersive X-ray spectroscopy revealed that the analysed concentrations are representative for the particle classes only, the composition of single particles in a particle class can deviate considerably.Display Omitted
Keywords: Biomass combustion; Cyclone fly ash; Heavy metal; Nutrients; Particle size;
Inherent process variations between fast pyrolysis technologies: A case study on Eucalyptus grandis by Jan-Erns Joubert; Marion Carrier; Nicolaus Dahmen; Ralph Stahl; Johannes Hansie Knoetze (389-395).
Fast pyrolysis of Eucalyptus grandis was carried out using different reactor configurations and scale setups, a 0.1 kg/h bubbling fluidised bed (BFB) reactor, a 1 kg/h BFB reactor and a 10 kg/h twin-screw reactor. The influence of lignocellulosic composition, process configuration (reactor configuration, separation and condensation system) and their feed capacity on yields and quality of pyrolysis products was discussed. The increasing reactor scale study had constraints such as the availability of biomass feedstock with inherent changes in the chemical composition and the practicality of the condensation chain. Although the methods employed for phase separation and liquid collection differ from plant to plant limiting the repeatability of results, it was clearly identified that the implementation of efficient solid separation and use of mineral oil as the coolant system were crucial aspects of the mass production of organics. These results suggest that yields and quality of fast pyrolysis at a larger scale are all process-related rather than feedstock conditioned. A comparison of energy balances indicated that fast pyrolysis retained the same energy yield at scales of 1 and 10 kg/h.
Keywords: Fast pyrolysis; Eucalyptus grandis; Scale effect; Energy balance;
Three-dimensional large eddy simulation of round liquid jet primary breakup in coaxial gas flow using the VOF method by Xiu-Shan Tian; Hui Zhao; Hai-Feng Liu; Wei-Feng Li; Jian-Liang Xu (396-402).
Large eddy simulation (LES) was performed on a liquid primary breakup process of twin-fluid atomizers with various dimensions. Volume of fluid (VOF) method was applied to track the unsteady evolution and breakup of the liquid jet. It was observed that the liquid primary breakup morphology of the thin central tube nozzle was more sensitive to the liquid inlet velocity distribution than that of the thick central tube nozzle, and the possible reasons were analyzed. The effect of liquid inlet velocity distributions on the primary breakup morphology was explored in detail. A criterion parameter was defined to assess the relative importance of liquid inlet velocity distributions on the liquid breakup shape of a selected atomizer. The combination of the present numerical scheme and the proper liquid inlet velocity distribution, which was determined by the dimensions of atomizers, was reliable and efficient for the numerical investigation of coaxial atomizer with various dimensions.
Keywords: LES/VOF; Primary breakup; Velocity distribution; Coaxial; Jet;
Performance of CuOx–neutral Al2O3 sorbents on mercury removal from simulated coal combustion flue gas by Wen Du; Libao Yin; Yuqun Zhuo; Qisheng Xu; Liang Zhang; Changhe Chen (403-408).
Copper based sorbents are used to control mercury emissions in coal-fired flue gas. CuOx impregnated on neutral Al2O3 (CuOx–Al2O3) sorbents were found to enhance catalytic oxidation of elemental mercury in the presence of hydrogen chloride (HCl). The Hg0 oxidation rates increased along with the increasing HCl concentration and temperature. The mercury oxidation rates were over 65% in the presence of 50 ppm HCl and the mercury adsorption amounts were over 75% in the early stage of the mercury removal process. CuOx–Al2O3 sorbents demonstrated good mercury removal capacity. The effect of HCl is due to the formation of active chlorine. CuOx–Al2O3 sorbents also have excellent sulfur resistance in the presence of HCl. A mixture of CuOx–Al2O3 and activated carbon can remove more than 90% Hg0 with a lower mercury removal cost for industrial applications. The characterizations of the CuOx–Al2O3 sorbents were measured suggesting CuOx species work as catalysts via the redox shift between Cu2 + and Cu+. The mercury oxidation mechanism of the sorbents is proposed to follow the Mars–Maessen mechanism.Display Omitted
Keywords: Mercury removal; Oxidation; Sorbent; CuOx; Flue gas;
Combustion dynamics of biodiesel produced by supercritical methanol transesterification by Jun Cheng; Tao Li; Na Peng; Rui Huang; Jun-Hu Zhou; Ke-Fa Cen (409-413).
The fatty acid methyl ester (FAME) compositions and combustion characteristics of the biodiesel produced from three plant oils under different supercritical methanol conditions were investigated by gas chromatography and thermobalance analyzers. When the reaction temperature increased from 255 to 300 °C, the conversion efficiency of rapeseed oil into FAMEs in biodiesel increased from 13% to 98%. Such increase resulted in an improved combustion property of rapeseed biodiesel with decreasing combustion activation energy from 143.6 to 84.2 kJ/mol. The ignition temperatures of the biodiesel produced from rapeseed, soybean and palm oils gradually decreased from 257.6 to 240.2 and 238.0 °C, which implied that the biodiesel with more C = C double bonds had higher ignition temperature. The ignition temperature of biodiesel was lower than that of raw plant oil, but higher than that of petroleum diesel.
Keywords: Biodiesel; Combustion dynamics; Activation energy; Transesterification; Supercritical methanol;
Investigating forward osmosis process for simultaneous preparation of brown coal slurry and wastewater reclamation by Wen-Xiu Gu; Ze-Xian Low; Yi Feng; Jing Wei; Huanting Wang (414-420).
The feasibility of using the forward osmosis (FO) process involving brown coal as draw agent to reclaim clean water from dye wastewater is evaluated in this study. It is found that brown coal not only has enough driving force for drawing water from dye wastewater but also can be reconstituted during the FO process, thus resulting in directly usable coal water slurry after appropriate FO time as an energy source equivalent to fossil oil or feedstock for chemical synthesis via gasification. In the FO process, water-drawing effect can significantly enhance the slurryability of brown coal via weakening the moisture holding capacity, decreasing the porosity and achieving the favorable particle size distribution due to the improved grindability. A possible tri-factor water-drawing and reconstitution mechanism of brown coal during the FO process is proposed to explain the effects of FO process on the properties of brown coal. The results indicate that the FO process promises to be a low-cost green process for simultaneous wastewater treatment and preparation of coal water slurry for environmental protection and energy production.
Keywords: Brown coal; Forward osmosis; Coal water slurry; Wastewater treatment;
Waste carbide slag as a solid base catalyst for effective synthesis of biodiesel via transesterification of soybean oil with methanol by Feng-Jiao Li; Hui-Quan Li; Li-Guo Wang; Yan Cao (421-429).
A highly efficient solid base catalyst was prepared from waste carbide slag and tested for biodiesel production from soybean oil with methanol. The effect of calcination temperature for carbide slag and various reaction parameters on the catalytic performances was systematically investigated. The carbide slag waste calcined at 650 °C (CS-650) exhibited 91.3% yield of fatty acid methyl esters (FAME) at reaction temperature of 65 °C, methanol/oil molar ratio of 9, catalyst/oil mass ratio of 1.0 wt.% within a short reaction time of 30 min, which was much higher than that of commercial CaO. Furthermore, the relationship between the surface basicity and activity indicated that stronger basicity was responsible for the higher catalytic activity. The merits of high catalytic activity, low cost, and abundant storage make the waste carbide slag a promising catalyst in the production of biodiesel.Display Omitted
Keywords: Biodiesel; Carbide slag; Soybean oil; Transesterification; Solid base;
Biosolubilization of Polish brown coal by Gordonia alkanivorans S7 and Bacillus mycoides NS1020 by Irena Romanowska; Bartosz Strzelecki; Stanisław Bielecki (430-436).
Two of five tested crude oil hydrocarbon-degrading bacteria, Gordonia alkanivorans S7 and Bacillus mycoides NS1020, solubilized crude and nitric acid-pretreated brown coal. Around 30–36% crude coal dry weight was solubilized within 14 days. The nitric acid pretreatment of the coal increased process efficiency by around 89% for G. alkanivorans S7. The extracellular coal-solubilizing activities of both the strains decreased with a decrease in pH, suggesting the contribution of some alkaline substances to lignite solubilization. Furthermore, this process was considerably intensified by ammonium oxalate. Mechanisms of lignite biosolubilization by the two strains were different because the active extracellular substances synthesized by B. mycoides NS1020 were thermostable while in the case of G. alkanivorans S7 some enzymes might be involved. Elemental analysis and FTIR spectra of 8N HNO3 pretreated coal and biosolubilization products generated by G. alkanivorans S7 and B. mycoides NS1020 showed significant differences between the lignite and these products. This is the first report presenting brown coal biosolubilization by crude oil hydrocarbon-degrading bacteria.
Keywords: Brown coal; Biosolubilization; Gordonia alkanivorans; Bacillus mycoides;
Novel CO2 sorbent: Ca(OH)2 with high strength by Zehua Li; Yin Wang; Hong Yao; Shiying Lin (437-442).
Using CaO-based sorbents to circularly absorb CO2 is one of the most interesting technologies for CO2 capture during coal combustion and gasification. The hydration step not only improves the reactivity of the CaO-based sorbent but also produces high-strength Ca(OH)2 particles for long-term CO2 absorption. A novel method of producing Ca(OH)2 with high strength (> 7.0 MPa) under different temperatures and/or steam partial pressures is proposed in this study. The mechanism and the particle breaking model are also discussed. Results indicate that high steam partial pressure and relatively low temperature are suitable conditions for the production of high-strength Ca(OH)2 particles. High steam partial pressure changes the particle structure, such as porosity, and thus enhances the strength of Ca(OH)2 particles. However, high temperature results in low Ca(OH)2 particle strength. This result may be due to the increase in the SBET of Ca(OH)2 particles. A particle breaking model has been developed to explain this. Furthermore, when Ca(OH)2 is decomposed to CaO, the strength of CaO particles becomes lower than that of the original Ca(OH)2. Lastly, a CO2 capture approach that involves the use of Ca(OH)2 particles with high strength is proposed.
Keywords: CO2 capture; Ca(OH)2 particle; Strength; Breaking model; Hydration;
Characterization of water extracts of oil shale retorting residues form gaseous and solid heat carrier processes by Janek Reinik; Natalya Irha; Eiliv Steinnes; Eero Piirisalu; Villem Aruoja; Eija Schultz; Matti Leppänen (443-451).
The present work focuses on the environmental effect of oil shale retorting residues originating from gaseous (GHC) and solid heat carrier (SHC) technologies. Samples were taken from Viru Keemia Grupp Oil factory (VKG Oil Ltd, Estonia). The water extracts of semi-coke samples from GHC retorting plants were non-toxic. The leachate water of SHC retorting ash was acutely toxic to Daphnia magna among tested organisms. The water extracts of semi-coke and retorting ash were acutely toxic at lower pH values and the release of anions and molybdenum increased significantly. The results show strong positive correlation between the toxicity and salinity/electric conductivity of the leachates. Release of anions in turn is related to the degree of decomposition of mineral phases during the retorting process.
Keywords: Oil shale; Semi-coke; Retorting ash; Toxicity;
Evaluation of Soxhlet extractor for one-step biodiesel production from Zanthoxylum bungeanum seeds by Lei Zhang; Hai-Tang Wu; Fang-Xia Yang; Jun-Hua Zhang (452-457).
Soxhlet extractor was applied for biodiesel production from Zanthoxylum bungeanum seeds containing high amount of free fatty acids (FFA) using methanol and ethanol as both extractants and reactants. The yields, fatty acid concentration and acid values of Z. bungeanum seed oil (ZSO) extracted with different solvents were determined. With a solvent-to-seed ratio of 6 (ml/g), extraction time of 4 h and water bath at 95 °C, the yields of ZSO with methanol and ethanol reached above 20%, which was almost as efficient as n-hexane, and the acid values of the corresponding ZSO were 56.9 and 41.9 mg KOH/g, respectively. The final acid values of ZSO were reduced to below 10 mg KOH/g when sulfuric acid was used as a catalyst presented in receiver flask in 4 h extraction and reaction. After 12 h of extraction and transesterification in a Soxhlet extractor with methanol and ethanol, the conversion of ZSO from Z. bungeanum seeds into ZSO biodiesel was almost complete as confirmed by 1H NMR. Application of the Soxhlet extractor for one-step biodiesel production from Z. bungeanum seeds containing high FFA avoided solid–liquid separation process and solvent wash, showing great potential of reducing the production cost of biodiesel.
Keywords: Biodiesel; Soxhlet extractor; Zanthoxylum bungeanum seeds; Methanol; Ethanol; Free fatty acids;
Effect of H2O on pyrite transformation behavior during oxy-fuel combustion by Fang Huang; Liqi Zhang; Baojun Yi; Zuojun Xia; Chuguang Zheng (458-465).
H2O concentration in an oxy-fuel furnace is higher than that in a conventional air combustion furnace. Pyrite is a dominant factor that contributes to slagging in pulverized coal-fired furnace. This study investigated the effect of H2O on pyrite transformation in the presence or absence of O2 atmosphere. The TGA with a Netzsch STA449F3 thermobalance using a water vapor furnace was applied in the study. The results showed that the onset temperature To and the end temperature Te of pyrite decomposition decreased as H2O partial pressure increased in O2-free atmospheres. Higher H2O concentration promoted the product iron sulfide of lower sulfur content—pyrrhotite FeS x (here 1 < x < 2), and magnetite transformed into hematite in O2-free atmospheres. The thermal decomposition temperature of pyrite is lower in H2O than that in CO2 atmosphere. In H2O atmosphere, the reaction between pyrrhotite and H2O may form magnetite, H2S and SO2 during the thermal decomposition of the pyrite. As H2O concentration increased, pyrite conversion and the release of sulfur were increased in CO2 atmosphere. In O2-containing atmospheres, the presence of H2O improved the initial transformation of pyrite, and an increase in O2 concentration also achieved similar results. However, the overall effect of H2O concentration was weak in O2-containing atmospheres. A comprehensive pathway of pyrite transformation during oxy-fuel combustion was proposed.Display Omitted
Keywords: Oxy-fuel combustion; Pyrite conversion; Water vapor; Mineral transformation behavior;
Operational characteristics of a passive methanol catalytic combustor assisting vapor generation for direct methanol fuel cells by Wei Yuan; Zhaochun Zhang; Jun Deng; Yong Tang; Binhai Yu (466-472).
Searching for a passive method to provide heat for a vapor-feed direct methanol fuel cell (DMFC) is still a challenging technical issue before it is put into practical use. This work develops a passive methanol catalytic combustor based on a pervaporation membrane, which is intended to be used as an assistant heat source for a vapor-feed DMFC. To validate the effectiveness of this method, a traditional bubbling-based system is prepared for comparison. Results show that the pervaporation operation outperforms the bubbling mode and facilitates self-ignition at a lower air feed rate (AFR). The increase of AFR promotes a higher permeation flux of methanol vapor, but may inversely cause heat loss because the enhanced air flow is apt to bring more heat away from the combustor. The AFR has dual effects on the processes of vapor generation and heat dissipation, which must be optimized to realize a balance between these two factors. The dynamic responses of catalyst temperature to the variation of AFR are also investigated in this work.
Keywords: Catalytic combustor; Methanol; Passive; Pervaporation; Air feed rate; Direct methanol fuel cell;
Synthesis and application of functionalized polymers for the removal of nitrogen and sulfur species from gas oil by Ali Abedi; Jackson Chitanda; Ajay K. Dalai; John Adjaye (473-482).
Functionalized polymers, which consist of polymer support, linker, and π-acceptor, have shown promising results in removing nitrogen and sulfur compounds from heavy gas oil via charge transfer complex (CTC) mechanism. In this work, the effect of polymer support in the efficiency and selectivity of the functionalized polymers toward nitrogen removal was studied by synthesizing three different polymers, consisting of hydrophilic and hydrophobic polymer supports, with the same linker and π-acceptor. Hydrazine (-H2N-NH2) and 2,4,5,7-Tetranitro-9-fluorenone (TENF) were chosen as the common linker and π-acceptor, respectively. The polymer supports were: polyacrylamide (PAM), polystyrene-co-divinylbenzene (PS-DVB), and polyglycidyl methacrylate-co-ethylene glycol dimethacrylate (PGMA-co-EGDMA). In the first stage, the functionalized polymers, PGMA-NN-TENF, PS-NN-TENF, and PAM-NN-TENF, were synthesized and characterized using different methods and techniques including Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA), CHNS elemental analysis, and Nuclear Magnetic Resonance (NMR) spectroscopy. A Nitrogen/Sulfur analyzer was used to determine total nitrogen and sulfur adsorption by the synthesized polymers in 4 different feeds: model compound (MC), light gas oil (LGO), heavy gas oil (HGO), and a blend of heavy and light gas oil (BGO). Results have shown that PGMA was the best polymer support with LGO, HGO, and BGO feeds, while PS-DVB showed the highest nitrogen removal with MC feed. The higher efficiency and selectivity of PGMA-NN-TENF toward nitrogen species, in the presence of sulfur and other aromatic species in the feed, were due to the combination of hydrophilic nature and high surface area of PGMA-NN-TENF compared to other polymers. Modifying the pretreatment conditions of the polymers with BGO feed showed that increasing temperature, contact time, and polymer to oil ratio increased the efficiency of the PGMA-NN-TENF polymer.
Keywords: Functionalized polymers; Polyglycidyl methacrylate-co-ethylene glycol dimethacrylate; Polystyrene-co-divinylbenzene; Gas oil; Nitrogen compounds;