Fuel Processing Technology (v.116, #C)
Editorial Board (IFC).
Enhancement of biodiesel production reaction employing the static mixing by Paweetida Sungwornpatansakul; Junko Hiroi; Yuuki Nigahara; Thumesha Kaushalya Jayasinghe; Kunio Yoshikawa (1-8).
Many reactors or mixers have been developed to enhance the reaction rate and reduce these requirements. In this research, a comparison of two mixing technologies, conventional mechanical mixer and the static mixer, was carried out. The conversion efficiency and kinetics show that the static mixer has a better performance. The static mixer has the potential to deliver better rigorous mixing between the raw oil and methanol, to the point that it can make the dispersed droplets of methanol in the raw oil smaller and more uniform, which resulted in enhancement of the reaction with the possibility of shortening the reaction time associated with biodiesel production.
Keywords: Biodiesel; Transesterification reaction; Static mixer; Reaction kinetics;
Syngas production by CO2/O2 gasification of aquatic biomass by Toshiaki Hanaoka; Shou Hiasa; Yusuke Edashige (9-15).
In the gasification of an aquatic biomass with He/CO2/O2, the effects of the concentration of CO2 and O2 in the gasifying agent and the feeding rate on the gasification behavior were investigated using a downdraft fixed-bed gasifier at 900 °C. Using CO2/O2 as the gasifying agent led to an increase in the conversion to gas and the syngas (CO + H2) content because the gasification of char with CO2 (C + CO2 → 2CO) and the decomposition of tarry compounds were promoted. Increasing CO2 content led to the increase in the conversion to gas and CO content and the decrease in the H2 content. With increasing O2 content, contents of CO and H2 increased while the conversions to gas remained almost constant. Especially with CO2/O2 = 45/55 vol.%, the conversion to gas was 94.0 C-mol% and the syngas content exhibited a maximum value of 69.7 vol.%. As the feeding rate was decreased, contents of CO and H2 decreased while the conversion to gas remained almost constant. The nitrogen atoms in the feedstock were mainly converted to form N2. H2S and COS were the main sulfurous gases. The sulfur content in the char was much higher than that in the feedstock.
Keywords: Biomass; Gasification; Aquatic biomass; Syngas;
Diesel-like hydrocarbon production from hydroprocessing of relevant refining palm oil by Worapon Kiatkittipong; Songphon Phimsen; Kunlanan Kiatkittipong; Suwimol Wongsakulphasatch; Navadol Laosiripojana; Suttichai Assabumrungrat (16-26).
This paper demonstrates the initiated use of relevant refining palm oil for bio-hydrogenated diesel production. The conversions of crude palm oil (CPO) and its physical refining including degummed palm oil (DPO) and palm fatty acid distillate (PFAD) to diesel fuel by hydroprocessing were studied. The effects of operating parameters (i.e. reaction time, operating temperature, and pressure) and catalyst (i.e. Pd/C and NiMo/γ-Al2O3) were examined in order to determine suitable operating condition for each feedstock. It was found that the hydroprocessing of CPO with Pd/C catalyst at 400 °C, 40 bar, and reaction time of 3 h provides the highest diesel yield of 51%. When gum which contains phospholipid compounds is removed from CPO, namely DPO, the highest diesel yield of 70% can be obtained at a shorter reaction time (1 h). In the case of PFAD, which consists mainly of free fatty acids, a maximum diesel yield of 81% could be observed at milder conditions (375 °C with the reaction time of 0.5 h). The main liquid products are n-pentadecane and n-heptadecane, having one carbon atom shorter than the corresponding fatty acids according to decarboxylation/decarbonylation pathways. Pd/C catalyst shows good catalytic activity for fatty acid feedstocks but becomes less promising for triglyceride feedstocks when compared to NiMo/γ-Al2O3.
Keywords: Bio-hydrogenated diesel (BHD); Hydrotreated vegetable oil (HVO); Green diesel; Renewable liquid fuel; Deoxygenation; Phosphorous;
Gas emissions from a large scale circulating fluidized bed boilers burning lignite and biomass by J. Krzywanski; R. Rajczyk; M. Bednarek; M. Wesolowska; W. Nowak (27-34).
Previously established and validated coal combustion model in a circulating fluidized bed (CFB) was employed to predict co-combustion of lignite and biomass processes. The validity of the model was successfully performed on a large-scale 261 MWe COMPACT CFB boiler. Forest biomass, sunflower husk, willow and lignite coal were applied in co-combustion tests with different shares of biomass and lignite. The energy fraction of biomass in fuel blend was: 7%, 10% and 15%. Emissions of CO2, CO, SO2 and NOx (i.e., NO + NO2) from the co-combustion tests, measured during experiments and predicted by model were compared. The gaseous pollutant emissions, evaluated using the developed model were in a good agreement with experimental results.
Keywords: Modeling; Co-firing; Circulating fluidized bed;
Lignite upgrading by multi-stage fluidized bed pyrolysis by Qi Zhou; Tao Zou; Mei Zhong; Yuming Zhang; Rongcheng Wu; Shiqiu Gao; Guangwen Xu (35-43).
This study is devoted to demonstrating experimentally the technical advantages of the multi-stage fluidized bed pyrolysis for upgrading lignite. A Chinese lignite was pyrolyzed and partially gasified in a three-stage laboratory-scale fluidized bed, with an overflow standpipe between its neighboring stages, to clarify the improvement on the pyrolysis product quality by increasing the number of the stages. While the bottom stage had the highest temperature of about 900 °C for fuel gasification, the upper stage had temperatures of 550–650 °C for coal pyrolysis. The multi-stage fluidized bed was operated with a continuous feed in the modes with one to three stages. The resulting yields of gas and tar were higher, whereas the yield of char was lower for the operations with multiple stages. The produced CO, H2 and CH4 in the two- and three-stage modes were more than that in the single-stage mode, having thus the higher gas heating value as well. The tar from the three-stage fluidized bed pyrolysis contained more light oil, and it plus phenol oil reached 99.5 wt.% of the tar. The char produced in the multi-stage pyrolysis showed the higher thermal stability in terms of its higher ignition temperature and suppressed spontaneous combustion propensity.This figure compares the product distribution obtained in pyrolyzing a kind of Chinese lignite in fluidized beds with one to three stages, showing that increasing the number of stages from one to three dramatically increased the pyrolysis gas yield from 45.9 wt.% to 87.8 wt.%. The tar yield slightly increased from 1.5 wt.% to 2.8 wt.%, whereas the char yield decreased from 54.8 wt.% to 36.3 wt.%. Thus, increasing the number of operation stages facilitated the pyrolysis reactions at their suitable temperatures by having longer reaction time, while on the other hand, the produced tar has low possibility to be cracked at high temperatures.Display Omitted
Keywords: Multi-stage fluidized bed; Lignite upgrading; Pyrolysis; Gasification; Lignite;
Deep desulfurization of gas oil over NiMoS catalysts supported on alumina coated USY-zeolite by Koji Nakano; Syed A. Ali; Hyun-Jong Kim; Taegon Kim; Khalid Alhooshani; Joo-Il Park; Isao Mochida (44-51).
A series of NiMoS catalysts supported on USY-zeolite coated with different amounts of alumina were prepared and evaluated for deep hydrodesulfurization (HDS) of gas oil using a flow reactor system in single- and dual-bed configurations. The performance of these catalysts was compared to the conventional HDS catalyst as well as to NiMoS catalyst supported on physical mixture of alumina and USY-zeolite. Physically mixed alumina and USY zeolite showed high HDS activity, but it was accompanied with significant cracking of hydrocarbons. Activity and kinetic analysis showed that heavy coating of alumina on the zeolite resulted in much lower HDS and cracking activity. On the other hand, very light coating of alumina on the zeolite resulted in catalytic behavior similar to that of physical mixture of USY-zeolite and alumina. The general trend was an increase in HDS as well as hydrocracking activity with the decrease in amount of alumina coating over zeolite. Changes in product density, aromatic content, mid-boiling point, cetane index, and molecular weight also reflected this trend. The results of this study indicate that catalysts with neither too low nor too high amount of alumina coating on the USY zeolite are suitable to achieve the balance between high HDS and low cracking activities. The highlight of the present study is that it confirmed the deep HDS activity of USY containing alumina supports in the flow reactor system which is industrially applied. In addition, the stability test confirmed the long-term performance of alumina-coated zeolite catalyst.
Keywords: Gas oil; Deep hydrodesulfurization; Alumina; Y-zeolite; Two-stage processing;
Deep desulfurization of model gasoline by selective adsorption over Cu–Ce bimetal ion-exchanged Y zeolite by Hua Song; Xia Wan; Min Dai; Jiaojing Zhang; Feng Li; Hualin Song (52-62).
Adsorbents were successfully prepared by liquid-phase ion-exchange of Y zeolites with Cu, Ce and combined Cu–Ce metal ions. The adsorbents were characterized by means of X-ray diffraction (XRD), N2-adsorption specific surface area measurements (BET), Fourier transform infrared (FT-IR), H2 temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) techniques. The adsorptive desulfurization properties of the adsorbents were studied in a fixed-bed unit through a model gasoline which was made up of 1-octane solution of refractory sulfur compounds (such as thiophene and benzothiophene) and certain amounts of toluene, pyridine or cyclohexene. Results indicate that CuICeIVY not only has a high sulfur adsorption capacity similar to CuIY but also has a high selectivity for sulfur compounds similar to CeIVY. For each sorbent, the selectivity of adsorption of sulfur compounds from liquid solutions followed the order: benzothiophene > thiophene. The effect on the metal ion-exchanged Y zeolites for sulfur removal was in the order: pyridine > cyclohexene > toluene. The high selectivity of CuICeIVY for sulfur removal can be attributed to the synergistic interaction between Cu+ and Ce4 +. The CuICeIVY zeolite binds organic sulfur compounds through two types of adsorption modes: π-complexation and direct coordination (S–M) interaction.Display Omitted
Keywords: Desulfurization; Adsorption; Adsorbent; Gasoline; Y zeolite;
Characteristics of waste printing paper and cardboard in a reactor pyrolyzed by preheated agents by Chunguang Zhou; Weihong Yang; Wlodzimierz Blasiak (63-71).
We studied the characteristics of waste printing paper and cardboard particles in a reactor pyrolyzed by preheated agents with the aim of simulating a real case in a fixed-bed gasifier. A TGA/DSC was first used to study of the kinetics and enthalpy change of the printing paper and cardboard pyrolysis. Pyrolitic conversion was further carried out in a batch-type reactor with non-electrical heating. Syngas, tar and char were produced and characterized from printing paper and cardboard pyrolysis at 400 °C, 500 °C and 600 °C. Different flow rates of carrier gas were applied to study the effect of residence time on the products distribution. When the flow rate increased, the relative mass change of gas agrees with that of tar. With increase in temperature, the yield of furfural, olefins and other non-aromatic compounds in tar decreased, while phenols and heavier aromatic hydrocarbons increased. The evolution of CO2, CO and other gas species in the syngas was presented. Van Krevelan diagram of chars was also presented in the paper.
Keywords: Printing paper; Cardboard; Pyrolysis; TGA/DSC;
CO2 hydrogenation to methanol over Cu/ZnO nanocatalysts prepared via a chitosan-assisted co-precipitation method by Thongthai Witoon; Tinnavat Permsirivanich; Waleeporn Donphai; Attasak Jaree; Metta Chareonpanich (72-78).
In this study, CuO–ZnO nanocomposites were prepared by chitosan-assisted co-precipitation method and performed as catalyst for CO2 hydrogenation to methanol. Effects of chitosan concentration on the physicochemical properties of the nanocomposites as well as the catalytic activity have been investigated. The obtained catalysts were characterized by means of scanning electron microscopy, X-ray diffraction, N2 adsorption–desorption, N2O chemisorption and temperature-programmed reduction. Chitosan was found to act not only as a coordination compound to produce a homogeneous combination of CuO–ZnO nanocomposite, but also as a soft template for the formation of hollow nanospheres. The CuO and ZnO crystallite sizes of the hollow nanospheres were found to be 11.5 and 18.8 nm, respectively, which were smaller than those of other catalysts. The increase of chitosan concentration caused a change in catalyst morphology and a reduction in BET surface area as well as metallic copper surface area, but still higher than those of the unmodified catalyst. The catalysts prepared by using chitosan as precipitating agent exhibited a higher space time yield of methanol than the unmodified catalyst, which was attributed to a synergetic effect of the CuO nanoparticle incorporated in the CuO–ZnO nanocatalyst. However, when the reaction temperature was increased up to 533 K, a decline in the space time yield of methanol was observed for the catalysts prepared at high chitosan concentration.
Keywords: Heterogeneous catalysis; Hollow sphere; Chitosan; Carbon dioxide; Nanomaterials;
Experimental study on propane combustion in a novel fluidized bed configuration by Farouk M. Okasha; El-Shafei B. Zeidan (79-84).
Experimental study on propane combustion has been performed in a novel fluidized bed configuration. This configuration has a jet that issues vertically in the upper part of the bed while allowing two methods of feeding. The first method is through jetting air–propane mixture that ensures smooth combustion avoiding burning bubble explosion. The second method enables staged-air combustion technique. Initial heating has been carried out by jetting propane partially premixed with air. The remaining part of air is fed through the distributor plate to fluidize bed solids. The proposed configuration enables a rapid and reliable method for initial heating of a fluidized bed combustor. The obtained results demonstrate that by applying the novel configuration, the freeboard overheating is greatly reduced. In accordance, the in-bed cooling load increases with increasing the secondary air ratio when applying the novel configuration. Alternatively, the temperature of the lower part of the freeboard fairly decreases while the temperature of the upper part considerably increases when applying the conventional method of air staging. Additionally the in-bed cooling load was found to significantly decrease with secondary air. The results also indicate that the novel configuration is more effective in reducing NOx. On the other hand, CO didn't exhibit significant change with increasing secondary air ratio applying the novel configuration while CO multiplies in the case of conventional operation.
Keywords: Fluidized bed combustion; Jet; Gaseous fuels;
A study of slow pyrolysis of one low rank coal via pyrolysis–GC/MS by Caroline Lievens; Donghui Ci; Yu Bai; Linge Ma; Rui Zhang; Jing Yun Chen; Qingqing Gai; Yinhua Long; Xiaofen Guo (85-93).
This paper describes the study of one low rank coal (LRC). To investigate its molecular structure, a LRC was characterized by proximate and ultimate analyses, XRD, FTIR, Raman spectroscopy, and pyrolysis–GC/MS (py–GC/MS). The light volatile fraction of LRC was characterized via py–GC/MS. LRC's aromatic ring structures consist of 59% amorphous structures, 22% of highly ordered structures with no less than 6 rings, 16% of aromatic structures characterized by aliphatic and/or ether substitutions and 3% of substituted benzene rings. XRD results show that the crystalline unit of LRC contains 1.44 aromatic carbon atoms per aliphatic carbon atom. Aromatic cluster structures within LRC are interconnected via ether- and covalent C―C bonds. Hydroxyl, ether and carbonyl functionalities give LRC its polar character. The slow pyrolysis of LRC resulted in a light volatile GC/MS detected fraction consisting of 20% aromatic ring compounds, 45% of phenolics, 30% of aliphatic hydrocarbons and 5% O-compounds, of which the concentration, evolution and nature were dependent on the heating rates and end temperatures. Generally, slow pyrolysis of LRC at 700 °C yielded the highest concentrations of unsaturated acyclic hydrocarbons, aromatics and phenolics.
Keywords: Low rank coal; py–GC/MS; Coal structure; Coal volatile fraction;
Effect of the oil acidity on the methanolysis performances of lime catalyst biodiesel from waste frying oils (WFO) by Ana Paula Soares Dias; Jaime Puna; Maria Joana Neiva Correia; Isabel Nogueira; João Gomes; João Bordado (94-100).
Biodiesel is a renewable fuel suitable to replace fossil fuel which can help to mitigate the carbon footprint of the transportation sector. Its price is still noncompetitive mainly due to the high price of raw materials (vegetable oils) and the costs of the processes. In order to find an efficient basic heterogeneous catalyst to replace the nowadays industrial caustic catalyst, a cheap CaO material was used to produce biodiesel using semi-refined rape seed oil (RSO). For the same catalyst the catalytic activity was tested with oleic acid acidified oil in order to simulate the use of low price materials with high activity. A linear decay of the Fatty Acid Methyl Ester (FAME) yield was observed, when oil acidity increases due to catalyst neutralization. The XRD and TG data showed that catalyst deactivation can be related with catalyst amorphization what can be related with soap formation. The catalytic tests with acidic waste frying oil (WFO) showed that biodiesel can be produced over CaO catalyst from low value raw materials without significant deterioration of the catalytic performances.Display Omitted
Keywords: Biodiesel; Methanolysis; Oil acidity; Waste cooking oils; Catalyst deactivation;
Investigation of the effects of steam injection on performance and emissions of a diesel engine fuelled with tobacco seed oil methyl ester by Adnan Parlak; Vezir Ayhan; İdris Cesur; Görkem Kökkülünk (101-109).
Although biodiesel is renewable, nontoxic, biodegradable and has low emission profiles, the main drawback of using biodiesel in diesel engines is higher NOx. In this study, steam injection has been used as a method to reduce NOx emissions of a direct injection diesel engine fuelled with tobacco seed oil methyl ester (TSOME). The effects of 10% (S10) and 20% (S20) steam ratio have been investigated in terms of performance and emissions of a diesel engine fuelled with 20% (B20) TSOME. Steam is injected into the inlet manifold during inlet period. It is shown that steam injection into the engine fuelled with B20 fuel improved torque, effective power, effective efficiency and specific fuel consumption (SFC) decreased. Whilst S10 has been found optimum at the low engine speeds, S20 is optimum at the high speeds for the performance. However, S10 has been found as optimum for the exhaust emissions. At this injection ratio, both NOx and smoke emissions decrease. As a result, steam injection is a found powerful tool for reducing NOx emissions of the diesel engines running with biodiesel blend.
Keywords: Diesel engine; Biodiesel; Tobacco seed oil; Steam; Performance; Emissions;
DSC study on combustion and pyrolysis behaviors of Turkish crude oils by Mustafa Versan Kok; Aslı Satı Gundogar (110-115).
This study focused on the investigation of non-isothermal thermal behavior and kinetics of Turkish crude oils under combustion and pyrolysis conditions using differential scanning calorimetry (DSC). On DSC combustion curves, two exothermic oxidation regions were detected known as low temperature (LTO) and high temperature oxidation (HTO). Again, two distinct reaction regions were revealed under pyrolysis conditions and DSC curves exhibited endothermic behavior for both the distillation and cracking regions. In consequence of thermal analyses, the heat of reaction amount was related to the °API gravity and accordingly to the asphaltene content of crude oils. It was proved that, with the decrease in °API gravity of crude oil, its heat release during HTO and heat requirement for cracking reaction increase. Experimental results showed that the reaction temperature intervals, peak temperatures and heat flows shifted to greater degrees for higher heating rates. With the application of ASTM I–II and Roger & Morris kinetic methods, it was observed that heavier oils with higher asphaltene content had greater activation energy and Arrhenius constant values.
Keywords: Differential scanning calorimetry; Crude oil; Reaction kinetics; Combustion; Pyrolysis;
Enhancement of attrition resistance and cyclic CO2 capture of calcium-based sorbent pellets by Huichao Chen; Changsui Zhao; Yanmei Yang (116-122).
Calcination/carbonation of calcium-based sorbent is considered one of the most promising technologies to capture CO2. The attrition resistance and CO2 uptake of Ca-based sorbent were of great concern. Efforts were made to enhance the attrition resistance of sorbents primarily by making sorbent pellets with aluminate cements and maintain high CO2 capture capacity of sorbents by adding pore forming agents. Batch experiments were conducted in a fluidized bed to investigate the effect of parameters on sorbent attrition. CO2 capture performance of the pellets was also examined in a calcination/carbonation reactor system. The pore structure characteristics (BET, BJH) were measured as a supplement to the attrition and reaction studies. Results showed that the mechanical property of the pellets with 10 wt.% aluminate cement was greatly enhanced. While, CO2 capture capacity of the pellets made with 10 wt.% aluminate cement and 5–10 wt.% pores forming agent was greatly increased and displayed much slower decay during multiple cycles compared with the original limestone. This was attributed to the large number of mesopores caused by the use of chemical agents and the exposure of inner core of CaO sorbents due to the attrition, which are in favor of CO2 capture. The pore structure showed that the BET surface area and BJH pore volume were expanded by adding pore forming agents, which benefits CO2 uptake of the sorbents during the cycling.
Keywords: CO2 capture; Attrition; Ca-based sorbent; Carbonation; Aluminate cement;
The influence of reaction parameters on characteristics of pyrolysis oils from waste high impact polystyrene and acrylonitrile–butadiene–styrene using a fluidized bed reactor by Su-Hwa Jung; Seon-Jin Kim; Joo-Sik Kim (123-129).
The aim of this study was to produce pyrolysis oils from waste high impact polystyrene (HIPS) and acrylonitrile–butadiene–styrene (ABS) in a pyrolysis plant equipped with a fluidized bed reactor. The influence of various reaction parameters, such as temperature, feed rate and the kind of fluidizing medium, was investigated. The maximum oil yields were about 87 wt.% (474 °C) for the HIPS and 84 wt.% (525 °C) for the ABS. A higher feed rate and the use of product gas as a fluidizing medium were favorable for the oil production. The oils produced from the HIPS pyrolysis consisted chiefly of toluene, ethylbenzene, styrene, cumene, α-methylstyrene and styrene dimers and they appeared to be usable directly as a fuel or chemical source. Main compounds of the ABS pyrolysis oils were similar to those obtained from the HIPS, except for nitrogen-containing compounds. In the nitrogen mass balance of the ABS pyrolysis products, most of the nitrogen was concentrated in the oil with a content of 6.5–7.1 wt.%. The pyrolysis oil from the ABS seemed to require further treatment for its use as a fuel source.
Keywords: Pyrolysis; Fluidized bed; High impact polystyrene; Acrylonitrile–butadiene–styrene; Nitrogen balance;
Assessment of the lubricant behaviour of biodiesel fuels using Stribeck curves by Marcia M. Maru; Rafael M. Trommer; Flávia A. Almeida; Rui F. Silva; Carlos A. Achete (130-134).
The molecular structure (carbon chain length, degree of unsaturation and branching of the chains) and the presence of contaminants in a biodiesel have a critical influence on their lubricant behaviour. Ball-on-disc tribological tests were performed with two different standard reference materials for biodiesel — NIST SRM 2772 (soybean) and NIST SRM 2773 (animal fat). It is demonstrated that the Stribeck curves, the plots of coefficient of friction (μ) vs. Stribeck parameter S (the product of viscosity with speed divided by the normal contact load), fit to a general polynomial equation of the type μ = μ 0 (1 − K BL × S + K EHL × Sn ). Constants K BL and K EHL reveal the contributions of the boundary lubrication (BL) and the elastohydrodynamic (EHL) phenomena, respectively. The animal fat biodiesel is the most effective fuel as it shows the highest K BL and the lowest K EHL values leading to the most stable coefficient of friction regarding speed variation. This behaviour is attributed to the higher content of contaminants, namely mono- and di-glycerides, and the presence of sulphur in the animal fat biodiesel.
Keywords: Biodiesel; Friction; Lubricant behaviour;
Long term storage stability of biodiesel: Influence of feedstock, commercial additives and purification step by Marta Serrano; Mercedes Martínez; José Aracil (135-141).
In the present work, the effect of four commercial additives, three synthetic (AO1, AO2 and AO3) and one natural based antioxidant (AO4), on the oxidation stability of biodiesel after six months of storage was investigated. Biodiesel fuel was obtained from different vegetable oils: Soybean, rapeseed, high oleic sunflower and palm methyl ester (SBME, RME, HOSME and PME, respectively). The influence of the washing agent used in the purification step (distilled water or a citric acid solution) was also studied. Samples were stored for a 6 month period at room temperature and not exposed to day light. Propyl gallate based antioxidant was found to provide the best oxidative stability after the storage period. Biodiesel obtained from low unsaturated feedstocks, such as palm oil, presented more oxidative stability than higher unsaturated oils, such as soybean oil. By purifying methyl ester phase with citric acid, the washing agent volume required resulted reduced. The antioxidant characteristic of citric acid enhanced the IP values of the samples, retarding the oxidation process.
Keywords: Biodiesel; Storage stability; Raw material; Commercial additives; Purification;
Hydrolysis of cellulose catalyzed by sulfonated poly(styrene-co-divinylbenzene) in the ionic liquid 1-n-butyl-3-methylimidazolium bromide by Guozhi Fan; Chongjing Liao; Tao Fang; Min Wang; Guangsen Song (142-148).
The hydrolysis of cellulose catalyzed by sulfonated poly(styrene-co-divinylbenzene) (SPS–DVB) was carried out in the ionic liquid 1-n-butyl-3-methylimidazolium bromide (BMIMBr), in which the reaction medium BMIMBr and sulfate polymer catalyst can be recovered. The influence of the amount of catalyst, water and ionic liquid, reaction conditions including reaction time and temperature was investigated in detail. The recovery of BMIMBr was performed based on using Aliquat 336 and naphthalene-2-boronic acid to extract the sugar derived from the hydrolysis of cellulose, and it was reused without further treatment. It was found that ionic liquid possessed excellent stability, and the conversion of cellulose almost kept constant during the recycles. The fresh and recovered sulfonated catalysts were characterized by means of TGA and IR, and the recovered catalyst was reused with/without treatment with acid. The catalytic activity almost kept constant in the case of regenerating by sulphuric acid prior to reuse, but a significant loss of activity was observed without regeneration. The results revealed that there may be an ion exchange process between the acidic sites of sulfonated catalyst and ionic liquid during the hydrolysis of cellulose.
Keywords: Hydrolysis; Cellulose; Ionic liquid; Sulfonated poly(styrene-co-divinylbenzene);
Hydropyrolysis characteristics and kinetics of potassium-impregnated pine wood by Limin Zhou; Yuyan Jia; Tuan-Huy Nguyen; Adesoji A. Adesina; Zhirong Liu (149-157).
Pine wood biomass (WB) samples impregnated with different potassium contents have been investigated to determine the influence of potassium on their hydropyrolysis behavior. The experiments were carried out using a thermogravimetric analyzer under both N2 and H2 atmosphere, and at the heating rate of 10 °C/min from room temperature to 700 °C. Results demonstrated that potassium effected on the biomass pyrolysis significantly, as evidenced by the changes in char content and characteristic parameters such as the maximum weight loss rates and the corresponding peak temperatures. The mass of char remaining after pyrolysis significantly increased with the impregnation of potassium acetate, but it did not increase proportionately to the potassium content. The temperature at which the maximum degradation rate occurs shifted to lower temperature, and this effect was more prominent for potassium-impregnated biomass pyrolysis under H2. It was also shown that the potassium had significant catalytic influence on the biomass pyrolysis, but this ability varied with the potassium content. The kinetic analysis indicated that both un-impregnated and potassium-impregnated biomass exhibited two-stage characteristics which could be kinetically described by two consecutive first order reactions. Moreover, the apparent kinetic compensation effect (KCE) has been observed for biomass pyrolysis under both N2 and H2.
Keywords: Hydropyrolysis; Kinetic; Biomass; Potassium;
Kinetics of thermal decomposition of phospholipids obtained from phosphate rock by Jale Naktiyok; Hatice Bayrakçeken; A. Kadir Özer; M. Şahin Gülaboğlu (158-164).
The soluble organic matter in the phosphate rock was extracted with n-hexane. Its structure was analyzed by using 1H NMR, 13C NMR and FTIR. 1H NMR and 13C NMR studies indicated that it has rather aliphatic nature. FTIR results showed that the bands obtained from organic matter exhibit a phospholipids characteristic. The kinetics of thermal decomposition of phospholipids obtained from phosphate rock was studied by means of thermal analysis techniques (TG/DTG) in nitrogen atmosphere at heating rates of 2.5, 5, 10, and 20 K min− 1. TG and DTG measurements indicated that thermal behavior of phospholipids has two-stage degradation. Kinetic parameters were determined from the TG and DTG curves for the stages I and II by using two model-free methods, i.e. Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose. The kinetic triplets consisting of Ea, A and g(α) models of the materials were determined. The average activation energies (Ea) obtained from both models for the decomposition of phospholipids are 64.15 kJ/mol and 122.3 kJ/mol and the pre-exponential factors ln(A) were 15.8 and 20.4 for stages I and II, respectively. The decomposition of phospholipids proceeds by two-dimensional diffusion (D2) for stage I, followed by three-dimensional diffusion (D5) for stage II.
Keywords: Phospholipids; Thermal decomposition; FWO and KAS methods;
Hydrotreating of C18 fatty acids to hydrocarbons on sulphided NiW/SiO2–Al2O3 by Yuhan Yang; Qingfa Wang; Xiangwen Zhang; Li Wang; Guozhu Li (165-174).
Hydrotreating of C18 fatty acids for biofuel production was investigated with dodecane as solvent in a fixed bed reactor. The effects of temperature (300 °C–375 °C), pressure (2 MPa–8 MPa), WHSV (4 h− 1–18 h− 1) and hydrogen to oil ratio (500 NmL/mL–1000 NmL/mL) on the oxygen removal reaction pathways of hydrodeoxygenation (HDO), decarbonylation/decarboxylation (DCO/DCO2) as well as α/β-C scission and isomerization reactions to form the C15–C18 hydrocarbons were systemically evaluated. For all experiments the same commercial Ni–W supported on modified SiO2–Al2O3 by NTY zeolite catalyst was used. The hydrotreating temperature is the most dominant operating parameter that affects the catalyst performance. The HDO to DCO/DCO2 ratio increases with decreasing temperature and/or increasing pressure. Low temperature and high WHSV will promote the isomerization reaction to cause more iso-paraffins in the products. The conversion of C18 fatty acids and/or product yield is little affected by the H2/oil ratio. Moreover, the concentration of C18 fatty acids in dodecane has a significant effect on the conversion of C18 fatty acids and C18 yield (HDO reaction), which decreases with the concentration of C18 fatty acids. Adsorbed hydrogen to fatty acid ratio has significant effect on deoxygenation pathways including C–O scission and C–C scission.
Keywords: C18 fatty acids; NiW/SiO2–Al2O3; C–C scission; C–O scission; Biofuel;
Design studies for monolithic high temperature shift catalysts: Effect of operational parameters by S. Ay; H. Atakül; G. Nezihi Özyönüm; A. Sarıoğlan; A. Ersöz; F. Akgün; P. Aksoy (175-181).
In this study, the performance of a commercial high temperature shift (HTS) catalyst has been investigated. The catalyst was a wash-coated ceramic monolith type and used to adjust the H2/CO ratio in a simulated syngas stream. In the experiments, the effects of inlet gas composition, gas hourly space velocity, inlet steam to CO ratio and reaction temperature have been investigated. The results showed that all these parameters have considerable influence on the design of HTS reactor. Precious metal based monolith catalysts enable working under high space velocities and thus reduce the volume of HTS reactor. Specifically defined selectivity, as ratio of the total amount of CO2 and H2 to the amount of CO2 formed during the process, seems to be a good measure of possible unwanted side reactions that might occur. It was found that the selectivity ratio should be ideally about two for HTS process, minimizing the formation of side reactions. Selectivity values below 2.0 indicate the presence of unbalanced H2 which is incompatible with WGS reaction stoichiometry. Results showed that steam is an effective parameter in determining the probability of side reactions, especially the reactions leading to the catalyst deactivation through coke deposition. Another point is that coking tendency of the catalyst is more severe at lower operating temperatures. The formation of methane, an unwanted by-product, was seen to be favored by lower gas hourly space velocities, possibly via the reaction with H2. The formation of methane results in hydrogen consumption to some extent and consequently alters the product composition. The optimum operating conditions of the wash-coated monolith type HTS catalyst studied were found to be as follows: Temperature = ~ 375–400 °C, GHSV = ~ 50,000 h− 1 and the inlet steam to CO ratio = ~ 2.0.Change of CO conversion and selectivity with inlet H2O/CO ratio, GHSV = 25,000 h− 1, inlet gas composition: 19.2%CO, 13.7%CO2, 67.1%H2, ……….. thermodynamic equilibrium at 360 °C, ----- thermodynamic equilibrium at 300 °C, ♦ at 300 °C, ◊ at 360 °C.At 360 °C, while CO conversion is increasing with inlet steam to CO ratio, WGS always overweighs on Boudouard reaction.At 300 °C, while CO conversion stays constant with inlet steam to CO ratio, the reaction shifts from WGS to Boudouard by increasing the steam load. This is the indication of the importance of operation temperature and inlet steam load determining the reaction path.Display Omitted
Keywords: WGS; Monolith; Coking; Optimization; CO content;
Glycerol acetals as diesel additives: Kinetic study of the reaction between glycerol and acetaldehyde by I. Agirre; M.B. Güemez; A. Ugarte; J. Requies; V.L. Barrio; J.F. Cambra; P.L. Arias (182-188).
Certain acetals can be produced from renewable resources (bioalcohols) and seem to be good candidates for different applications, such as oxygenated diesel additives. This paper addresses the production of acetals (5-hydroxy-2-methyl-1,3 dioxane and 4-hydroxymethyl-2-methyl-1,3 dioxolane) from glycerol and acetaldehyde using Amberlyst 47 acidic ion exchange resin. This ion exchange resin performed well, recording 100% selectivity toward acetal formation at a suitably high initial glycerol concentration. When the initial acetaldehyde concentration was significantly higher than the glycerol concentration, 2,4,6 trimethyl-1,3,5 trioxane was the main reaction product. Unlike other acetalization reactions, the one studied here does not have thermodynamic limitations, and 100% conversion is achieved under different reaction conditions. A kinetic study was performed in a batch stirred tank reactor to study the influence of different process parameters, such as temperature, feed composition and stirring speed. A pseudo-homogeneous kinetic model was developed to describe this reaction kinetics, proving that its rate is just first order on the acetaldehyde concentration under the conditions studied.
Keywords: Glycerol; Acetaldehyde; Acetals; Kinetics; Amberlyst;
Numerical study of a 350 MWe tangentially fired pulverized coal furnace of the As Pontes Power Plant by I. Constenla; J.L. Ferrín; L. Saavedra (189-200).
The aim of this investigation is predicting the flow characteristics with real operating conditions of a boiler to better understand the phenomena occurring in the interior of the furnace and to validate the models chosen for the simulation. For this purpose, we have done a numerical study of the flow of a reactive gas mixture with pulverized coal combustion occurring in a tangentially fired furnace of a real power plant. These calculations were developed with the commercial software ANSYS Fluent. Furthermore, a home-made code was built to perform some necessary preprocessing and postprocessing calculus. In particular, this code solves zero-dimensional balances that have provided a good agreement with the calculated and measured flow at the exit of the furnace and it is also used to validate the convergence of the numerical algorithm for the three-dimensional simulation. The results obtained from this study show that models and numerical methods selected are appropriate to correctly predict the combustion processes within the furnace. In conclusion, the validation of this numerical model and our home-made code provides the user a complete tool to evaluate the performance of a boiler under different operating conditions, reducing the cost of experimental tests.
Keywords: CFD; Pulverized coal combustion; Industrial furnace; Zero-dimensional balances;
Oxidation behavior of particulate matter sampled from the combustion zone of a domestic pellet-fired boiler by Ulisses Fernandes; Marta Guerrero; Ángela Millera; Rafael Bilbao; María U. Alzueta; Mário Costa (201-208).
This article describes an experimental investigation of the oxidation behavior of particulate matter (PM) sampled with the aid of a rapid dilution probe from a number of measurement positions located in the near the burner region of a domestic wood pellet-fired boiler. Morphology and chemical composition of the collected PM samples were examined in a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy detector. To evaluate the oxidative reactivities of the PM samples, experiments were performed in a quartz reactor with an inlet oxygen concentration of 500 ppm in a nitrogen flow, a temperature of 900 °C, and a flow rate of 1000 mL/min (STP). Results obtained from the oxidation tests indicated that the PM samples collected from locations near the visible flame boundary were significantly less reactive towards O2 than those sampled from locations along the burner axis. This fact may be due to the higher temperatures occurring near the visible flame boundary, resulting in PM samples with a higher degree of material organization and a lower availability of active sites.
Keywords: Biomass; Pellets; Domestic boiler; Particulate matter; Reactivity;
Prediction of sour gas compressibility factor using an intelligent approach by Arash Kamari; Abdolhossein Hemmati-Sarapardeh; Seyed-Morteza Mirabbasi; Mohammad Nikookar; Amir H. Mohammadi (209-216).
Compressibility factor (z-factor) values of natural gasses are essential in most petroleum and chemical engineering calculations. The most common sources of z-factor values are laboratory experiments, empirical correlations and equations of state methods. Necessity arises when there is no available experimental data for the required composition, pressure and temperature conditions. Introduced here is a technique to predict z-factor values of natural gasses, sour reservoir gasses and pure substances. In this communication, a novel mathematical-based approach was proposed to develop reliable model for prediction of compressibility factor of sour and natural gas. A robust soft computing approach namely least square support vector machine (LSSVM) modeling optimized with coupled simulated annealing (CSA) optimization tool was proposed. To evaluate the performance and accuracy of this model, statistical and graphical error analyses have been used simultaneously. Moreover, comparative studies have been conducted between this model and nine empirical correlations and equations of state. The obtained results demonstrated that the proposed CSA-LSSVM model is more robust, reliable and efficient than the existing correlations and equations of state for prediction of z-factor of sour and natural gasses.
Keywords: Z-factor prediction; Sour and natural gas; Least square support vector machine; Coupled simulated annealing; Empirical correlation; Equation of state;
Catalytic conversion of C4 fraction for the production of light olefins and aromatics by Xianghai Meng; Zhixi Wang; Rui Zhang; Chunming Xu; Zhichang Liu; Yadong Wang; Qiang Guo (217-221).
The catalytic conversion of the C4 fraction from a fluid catalytic cracking (FCC) unit over a commercial FCC equilibrium catalyst was investigated using a confined fluidized bed reactor system. Butenes were easier to convert than butanes, and 1-butene was the easiest to convert among the butene isomers. The ethene and propene yields increased with increased reaction temperature and decreased with increased weight hourly space velocity (WHSV). The formation of propene involved two successive steps: butene dimerization and large hydrocarbon cracking. Aromatics were formed by the aromatization of the intermediate large olefins. A mechanism parameter R CA was proposed to describe the relative function of the cracking reaction to the aromatization reaction. R CA increased with increased reaction temperature and decreased with increased WHSV. The cracking reaction predominates on the aromatization reaction at high reaction temperatures.Display Omitted
Keywords: Catalytic conversion; Butene; Butane; Cracking; Propene; Aromatics;
Hydrocracking of 1-methylnaphthalene/decahydronaphthalene mixture catalyzed by zeolite-alumina composite supported NiMo catalysts by Atsushi Ishihara; Tomohiro Itoh; Hiroyuki Nasu; Tadanori Hashimoto; Takao Doi (222-227).
Various zeolite-alumina composites supported NiMo catalysts were prepared and their properties for hydrocracking of a decahydronaphthalene (decalin) solution containing 10 wt.% of 1-methylnaphthalene (1-MN) and 0.1 wt.% of dibenzothiophene were investigated in order to estimate not only hydrocracking of hydrocarbons but also isomerization and hydrogenation of 1-MN. 1-MN was converted to 2-MN for almost all the catalysts. The hydrogenation activities to form methyltetralin decreased in the order NiMo/Beta(940)60A > NiMo/Beta(980)60A > NiMo/HY(5.5)60A > NiMo/USY(390)60A > NiMo/USY(360)60A > NiMo/ZSM60A at 300 °C where Beta(940) β zeolite with SiO2/Al2O3 = 37, Beta(980) β zeolite with SiO2/Al2O3 = 500, HY(5.5) Y zeolite with SiO2/Al2O3 = 5.5, USY(360) dealuminated Y zeolite with SiO2/Al2O3 = 14, USY(390) dealuminated Y zeolite with SiO2/Al2O3 = 400, ZSM ZSM-5 zeolite with SiO2/Al2O3 = 1500, 60A alumina content in a composite support. Hydrocracking was observed at 360 °C specifically for β zeolite containing catalysts and the highest yields of benzene, toluene and xylene were obtained for NiMo/Beta(940)35A. It is elucidated that mesopore is favorable for hydrocracking and that the strength of the acid sites as well as homogeneous dispersion of metal species played an important role.Effect of temperature on total conversion and conversion of MN into MT.Display Omitted
Keywords: NiMo catalyst; Zeolite-alumina composite supports; Hydrocracking; Hydrogenation; 1-methylnaphthalene; β zeolite;
The effect of chipper cut length on wood fuel processing performance by Alessio Facello; Eugenio Cavallo; Natascia Magagnotti; Giuseppe Paletto; Raffaele Spinelli (228-233).
The authors tested the same chipper under two alternative cut length settings (7 mm and 20 mm), with and without a piece breaker. The study included 10 repetitions per treatment, over 2 different feedstock types: chestnut logs and locust logs. The total number of repetitions was 80, each consisting of about 30 kg of logs. Cut length setting and piece breaker option are the main drivers of chip size, and they are manipulated with the main purpose of managing particle size distribution. Our study showed that the proportion of small chips increased dramatically with the shortest cut length setting (7 mm). Installing a piece breaker allowed maximizing the incidence of small chips, which reached 70% of the total mass when the piece breaker was used in combination with the shortest cut length setting. All else being equal, reducing cut length determined a substantial decrease of productivity (ca. 30%), and an even higher increase of specific fuel consumption (ca. 50%). All strategies to reduce chip size also resulted in increasing the incidence of fines. These results were obtained with new sharp blades. Blade wear may enhance or weaken the effect of cut length and piece breaker option.
Keywords: Biomass; Energy; Chips; Productivity; Fuel consumption;
Catalytic steam reforming of cellulose-derived compounds using a char-supported iron catalyst by Yi Wang; Xun Hu; Yao Song; Zhenhua Min; Daniel Mourant; Tingting Li; Richard Gunawan; Chun-Zhu Li (234-240).
This study aims to understand the mechanism for the removal of tar in the gasification of biomass with a char-supported iron catalyst. The pyrolysis of a pure cellulose sample and the following steam reforming of the pyrolysis products have been performed at temperatures from 500 to 850 °C. Our results indicate that tars are hard to be reformed without a catalyst. At low temperatures (< 700 °C), compared with aromatic structural systems, the catalytic steam reforming showed better effects on the conversion of non-aromatics (e.g. sugars), particularly large molecules. Many aromatic ring systems can be formed at high temperatures (≥ 700 °C), and the catalyst was effective on reforming them with steam. The char structural features of a catalyst gave more information to understand the reactions that occurred on the catalyst.
Keywords: Catalytic steam reforming; Cellulose-derived compounds; Char-supported iron catalyst; Tar;
Ultrasound assisted interesterification of waste cooking oil and methyl acetate for biodiesel and triacetin production by Ganesh L. Maddikeri; Aniruddha B. Pandit; Parag R. Gogate (241-249).
Intensification of the interesterification reaction of waste cooking oil with methyl acetate using potassium methoxide as a catalyst has been carried out using ultrasonic horn (frequency of irradiation of 22 kHz and rated power of 750 W). Experiments have been performed at different operating parameters viz. reaction temperature (30, 40 and 50 °C), oil to methyl acetate molar ratio (over the range of 1:4 to 1:14), catalyst concentration (0.5, 1.0 and 1.5% by weight of oil) and amplitude of ultrasound (40, 50, 60 and 70%) with an objective of understanding the effect of important operating parameters on the extent of conversion of waste cooking oil to the ester. It has been observed that maximum yield (90%) of biodiesel from waste cooking oil using sonochemical reactors was observed at a molar ratio of 1:12, catalyst concentration of 1.0% and temperature of 40 °C. It is also observed that higher conversion was obtained in the presence of ultrasound as compared to the conventional method. Kinetic studies have been carried out to determine the rate constant by fitting the obtained experimental data to a second-order rate equation. It has been observed that rate constant increases with an increase in temperature and the activation energy is found to be 56.97 kJ/mol.
Keywords: Biodiesel; Waste cooking oil; Interesterification; Process intensification; Ultrasound;
Chemometric approach for assessing the quality of olive cake pellets by Tea Brlek; Lato Pezo; Neven Voća; Tajana Krička; Đuro Vukmirović; Radmilo Čolović; Marija Bodroža-Solarov (250-256).
This article investigates the influence of processing parameters (conditioning and binder content), on quality of fuel agro-pellets produced from four olive cultivars (Istarska Bjelica, Buža, Pendolino, Leccino) grown in experimental filed in Croatia (Istria). Physical and chemical properties of pellets have been determined to assess their quality. Low ash and sulphur levels were detected, with elevated nitrogen levels for all samples. Analysis of variance and post-hoc Tukey's HSD test at 95% confidence limit have been utilised to show significant differences between various samples. Low coefficients of variation have been obtained for each applied assay (0.09–2.98%), which confirmed the high accuracy of the measurements. Score analysis and principal component analysis have been used for assessing the effect of process variables and variety of cultivars on final quality of pellets. For PCA modelling, experimental data for physical and chemical properties have been used. Standard score analysis revealed that equally good physical and chemical characteristics of pellets can be obtained with conditioning at 50 °C, but also without conditioning. The use of binders didn't affect the quality of pellets as much.
Keywords: Olive cake; Olive cultivar; Fuel pellets; Agro-pellets;
Adsorptive desulfurization of low sulfur diesel fuel using palladium containing mesoporous silica synthesized via a novel in-situ approach by Mohammad Teymouri; Abdolraouf Samadi-Maybodi; Amir Vahid; Aliakbar Miranbeigi (257-264).
In this work, a novel in-situ synthesis route was applied for preparation of an adsorbent, i.e. palladium containing MCM-41. At first, a hydrophobic palladium precursor was added to the ethanolic micellar solution followed by vacuum distillation of ethanol which decreases the hydrophobic characteristic of the solution. Distillation caused diffusion of hydrophobic palladium precursor into the hydrophobic core of the micelles. Then, tetraethyl orthosilicate was added to the above solution and the silicate spices arranged around the palladium containing micelles. The XRD, N2 physisorption and TEM studies revealed that 4 wt.% palladium loading was achieved without considerable loss of pore ordering. H2-TPR showed that the palladium nanoparticles were accessible for hydrogen molecules. Adsorptive desulfurization of low sulfur diesel fuel was then investigated using synthesized samples. The effect of three valuable parameters, i.e., temperature (25, 75, 150 and 200 °C), concentration of palladium (2, 4 and 5 wt.%) and feed flow rate (0.3 and 1 mL/min) were tested using a fixed-bed flowing device. The highest sulfur break through adsorption capacity and total sulfur adsorption capacity obtained at 200 °C, 0.3 mL/min of feed flow rate and 4 wt.% of palladium concentration were 1.67 and 2.35 mg sulfur/g adsorbent, respectively.
Keywords: Adsorptive desulfurization; Diesel; In situ synthesis; Mesoporous materials; Nanoparticles; Palladium;
Facile introduction of Cu+ on activated carbon at ambient conditions and adsorption of benzothiophene over Cu+/activated carbon by Nazmul Abedin Khan; Zubair Hasan; Kil Sik Min; Seung-Min Paek; Sung Hwa Jhung (265-270).
CuCl-supported carbon based adsorbents were prepared, for the first time, through a facile and mild reduction of CuCl2 to improve the desulfurization capability of the porous activated carbon (AC). Reduction of CuCl2 was carried out at room temperature and atmospheric pressure with sodium sulfite as a mild reducing agent. Liquid-phase adsorption of benzothiophene (BT) over CuCl/ACs was studied to understand the effect of Cu+ on adsorption/removal. The CuCl-supported AC adsorbed around 30% more BT with faster adsorption kinetics compared with the virgin AC. Since the surface area and pore volume of the AC decreased with the loading of the copper species, the increased adsorption capacity over the Cu+-supported AC adsorbents suggests the formation of a π-complex between Cu+ and BT. Additionally, in the presence of air/moisture, the obtained Cu+ species oxidized readily to a Cu2 + state and showed a negligible increment in adsorptive desulfurization compared with the virgin AC; therefore, the adsorbent should be stored/applied under an inert atmosphere.Display Omitted
Keywords: Supported cuprous ion; Facile reduction; Activated carbon; Desulfurization; Adsorption;
Prediction of liquid yields from the pyrolysis of waste mixtures using response surface methodology by Filomena Pinto; Filipe Paradela; Ibrahim Gulyurtlu; Ana Maria Ramos (271-283).
The main objective of this work was to predict the influence of experimental conditions on product yields formed by waste mixtures pyrolysis, using response surface methodology (RSM). Accurate prediction of liquid yields at different experimental conditions and pyrolysis optimisation was achieved. The waste mixture studied contained 10% of pine, 10% of scrap tyres and 80% recycled plastic, whose main components were polyethylene (PE), polypropylene (PP) and polystyrene (PS). Experiment Factorial Design was used for the optimisation of reaction time, temperature and initial pressure to maximise the yield and composition of liquid products for the waste mixture studied. Experimental yields of liquids were fitted with a linear and second order model by the method of least squares with good correlation and high statistical significance. According to the model, the production of total pyrolysis liquids (including those obtained by solvent extraction) was maximised when the following conditions were used: reaction temperature of 350 °C, reaction time of 30 min and initial pressure of 0.2 MPa, leading to liquid yield of 91.3% (w/w). The yield of only decanted liquids (not considering those obtained by solvent extraction) was maximised to the value of 54.9% at 426 °C, 28 min and 0.2 MPa. The total liquid production at these conditions was 79.1%. The results obtained also showed that the approach used may be suitable for optimizing the experimental conditions that favour the formation of chosen gaseous and liquid compounds.
Keywords: Wastes; Pyrolysis; Plastics; Tyres; Pine; Response surface methodology;
Assessment of limestone treatment with organic acids for CO2 capture in Ca-looping cycles by Firas N. Ridha; Vasilije Manovic; Arturo Macchi; Michael A. Anthony; Edward J. Anthony (284-291).
The main challenge for CO2 capture in calcium looping cycles is the decay of CO2 carrying capacity of the CaO-based sorbents with increasing number of cycles. In this work, limestone was treated with organic acids and tested for CO2 capture in calcium looping cycles to understand how practical and reliable the treatment is for CO2 looping capture. The results showed that after 20 cycles the carbonation conversions of limestone treated with acetic acid, vinegar, formic acid, and oxalic acid were 33.1%, 21.1%, 31%, and 35.2%, respectively, compared to 18.9% for untreated limestone. The treatment with organic acids clearly improves the sintering-resistance properties of the modified sorbent. However, the activity of these sorbents was found to decline in similar fashion to that of untreated limestone. It was concluded that although limestone treatment with organic acids enhances CO2 capture capacity, the enhancement is marginal in most cases while the treatment increases the cost of CO2 capture significantly. Accordingly, the treatment may not be an adequate approach if the goal is to maintain low-cost capture of CO2; moreover, treated sorbents which perform well for CO2 capture do also perform well for SO2 capture, causing their capacity to decline at least as rapidly as a natural untreated sorbent and often more so.
Keywords: Calcium looping; CO2 capture; Organic acid; Limestone; Sorbent;
Steam gasification of biomass in a conical spouted bed reactor with olivine and γ-alumina as primary catalysts by Aitziber Erkiaga; Gartzen Lopez; Maider Amutio; Javier Bilbao; Martin Olazar (292-299).
Olivine and γ-alumina have been used as primary catalysts for tar elimination in the continuous steam gasification of pine wood sawdust in a bench-scale plant provided with a conical spouted bed reactor. A comparison of the performance of each catalyst with that observed for a bed made up of inert silica sand shows that both catalysts have a significant activity for tar cracking/reforming, given that the amount of tar obtained by operating with beds of inert sand is reduced by 79% and 84% when olivine and γ-alumina are used, respectively. The tar cracking reduces selectively the content of light and heavy PAHs, giving way to an increase in the concentration of light aromatics. Furthermore, both catalysts cause a positive effect on the gas composition by slightly enhancing the water–gas shift and reforming reactions.
Keywords: Steam gasification; Tar cracking; Biomass; Spouted bed; Olivine; γ-alumina;
Inorganic constituents formed during small-scale gasification of poultry litter: A model based study by Carolina Font Palma; Alastair D. Martin (300-307).
Europe's vast poultry industry requires a proper waste management in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process simulation for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. The system allows the treatment of waste with the additional benefit of energy generation. A small-scale system (200 kWe) installed on-site the biomass source shows to be suitable for a poultry farm to avoid the litter transportation to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and tar, ash represents a potential risk since bed agglomerates can lead to loss of fluidisation and alkali vapours in the product gases can increase rates of hot corrosion on turbine surfaces. This work presents the partition of the most problematic inorganic species in order to assess the feasibility of the system and identify the optimum parameters to minimise the vaporisation of inorganics. It was found that low ER values produced low HCl emissions and good process efficiencies but released very high SO2 emissions.
Keywords: Ash chemistry; Gasification; Poultry litter; Exergy efficiency; Aspen plus; Alkalis;
Promoting gas production by controlling the interaction of volatiles with char during coal gasification in a circulating fluidized bed gasification reactor by Koichi Matsuoka; Sou Hosokai; Yoshishige Kato; Koji Kuramoto; Yoshizo Suzuki; Koyo Norinaga; Jun-ichiro Hayashi (308-316).
A novel circulating fluidized bed (CFB) gasifier, which consists of a downer and two bubbling fluidized beds, was developed. Coal is continuously pyrolyzed in the downer and the resultant char is sent to the bubbling bed gasifier for steam gasification while evacuation of the volatiles avoids the char–volatile interactions. Any ungasified char is transferred from the gasifier to the bubbling bed combustor, where it is either completely combusted or partially combusted and then recycled to the downer. Steam gasification was successfully performed in the absence of pyrolysis-derived volatiles, which strongly inhibit gasification. The recycling of the partially combusted char greatly increased its concentration in the downer thereby enhancing the reforming of the volatiles, in particular that of tar over that of char, and the resultant gas formation. The total yield of gases from the downer and bubbling bed gasifier was 45% higher than that obtained under direct feeding of the coal into the bubbling bed gasifier and full combustion of the char, i.e., with steam gasification of char in the presence of volatiles and subsequent reforming over char at a much lower concentration.
Keywords: Coal; Fluidized bed; Gasification; Inhibition; IGCC;
Toward a predictive model for estimating dew point pressure in gas condensate systems by Milad Arabloo; Amin Shokrollahi; Farhad Gharagheizi; Amir H. Mohammadi (317-324).
Dew-point pressure is one of the most important quantities for characterizing and successful prediction of the future performance of gas condensate reservoirs. The objective of this study is to present a reliable, computer-based predictive model for prediction of dew-point pressure in gas condensate reservoirs. An intelligent approach based on least square support vector machine (LSSVM) modeling was developed for this purpose. To this end, the model was developed and tested using a total set of 562 experimental data points from different retrograde gas condensate fluids covering a wide range of variables. Coupled simulated annealing (CSA) was employed for optimization of hyper-parameters of the model. The results showed that the developed model significantly outperforms all the existing methods and provide predictions in acceptable agreement with experimental data. In addition, it is shown that the proposed model is capable of simulating the actual physical trend of the dew-point pressure versus temperature for a constant composition fluid on the phase envelope.
Keywords: Dew-point pressure; Gas condensate; Support vector machine; Empirical correlations; Computer program;
Synthesis of mesoporous MgO catalyst templated by a PDMS–PEO comb-like copolymer for biodiesel production by Harim Jeon; Dong Jun Kim; Sang Jin Kim; Jong Hak Kim (325-331).
Mesoporous MgO catalyst was synthesized from Mg(NO3)2 via a sol-gel process by templating an amphiphilic comb-like copolymer, poly(dimethylsiloxane–ethylene oxide) (PDMS–PEO). The copolymer morphology was worm-like and microphase-separated in a good solvent but micellar in a selective solvent, such as toluene and water. By templating micelles of PDMS–PEO copolymer, mesoporous MgO with a high surface area was generated after calcination at 500 °C, as confirmed by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption/desorption measurements. Mesoporous MgO was used as a heterogeneous solid catalyst to produce biodiesel from canola oil. PDMS–PEO templated MgO (t-MgO) converted biodiesel more efficiently (~ 98.2% methyl ester content) than non-templated MgO (nt-MgO, 82.8%). The number and strength of basic sites of MgO catalyst were also investigated using CO2-temperature-programmed desorption (CO2-TPD) analysis.Mesoporous MgO catalyst was synthesized from Mg(NO3)2 via a sol-gel process by templating an amphiphilic comb-like copolymer, poly(dimethylsiloxane-ethylene oxide) (PDMS-PEO). PDMS-PEO templated MgO (t-MgO) converted canola oil to biodiesel more efficiently (~ 98.2% methyl ester content) than non-templated MgO (nt-MgO, 82.8%) due to larger surface area and basic site density.Display Omitted
Keywords: Biodiesel production; Catalyst; MgO; Sol-gel; Comb-like copolymer;
Increasing coal quality by oil agglomeration after ultrasonic treatment by Ercan Sahinoglu; Tuncay Uslu (332-338).
In the present study, oxidized and high sulphur fine coal was subjected to oil agglomeration process after ultrasonic treatment. Power and time of ultrasonic treatment were selected as variable. Combustible recovery, ash rejection, pyritic sulphur rejection, ash separation efficiency and pyritic sulphur separation efficiency of the agglomeration process with and without ultrasonic treatment were determined. In addition, calorific value of the clean coal produced by agglomeration process was measured. In the agglomeration process without ultrasonic treatment, calorific value, combustible recovery, ash rejection and pyritic sulphur rejection were obtained to be 6518 kcal/kg, 63.78%, 75.19% and 92.64%, respectively. Ultrasonic treatment enhanced the performance of oil agglomeration process. By the application of ultrasonic treatment before agglomeration process, calorific value, combustible recovery, ash rejection and pyritic sulphur rejection were increased to maximally 6939 kcal/kg, 66.13%, 87.24% and 97.44%, respectively. In the study, changes on the surface structure of the coal after ultrasonic treatment were also examined. Particle breakage, formation of cracks and cavities, and altering of surfaces into fresh-clean surfaces were observed. Increase in time and power of ultrasonic treatment had slight positive effect on ash and pyritic sulphur rejections.
Keywords: Coal; Desulphurization; Deashing; Oil agglomeration; Ultrasonic treatment;
“Deviceless” self-sustained oscillatory diffusive burning of TBPB and hybrid fuels by Kirti Bhushan Mishra; Klaus-Dieter Wehrstedt (339-345).
An extraordinary deviceless self-sustained oscillatory diffusive burning is observed in tert-butyl peroxybenzoate (TBPB) (technical pure) and hybrid fuel, i.e., TBPB and kerosene (both 50%) flames when burned in form of pool fires. Such oscillations or more precisely self-sustained deviceless control of mass burning (flow) is not reported till date. Generally, devices comprising electronic control system and/or mechanical means (valves) are necessary to produce such oscillatory burning or control of fuel flow. This unique oscillation is strongly recorded for pool diameters of 6 cm ≤ d ≤ 11 cm beyond which the effect was weakened and unseen (hid) visually. The fuel regression (loss) takes place in irregular time steps and is formulated in form of a step function. The variation in fuel mass burning rates, visible flame lengths and radiation heat fluxes with time are measured as respective representatives of oscillations. The periodicity in the strongest oscillations in relative visible flame lengths is investigated and the measured data are found to be best fitted in sinusoidal form. Both, chemical and thermal effects are shown to be possibly responsible for such effects. Furthermore, a theory is offered to characterise similar effect showing fuels.Periodic oscillation (W-Effect) in a TBPB pool flame (d = 6 cm) [5,9,10].Display Omitted
Keywords: Self-sustained; Oscillatory burning; TBPB; Kerosene; Diffusion flame; Flow rate control;
Synthesis and characterization of activated carbon from natural asphaltites by B. Tsyntsarski; S. Marinov; T. Budinova; M. Ferhat Yardim; N. Petrov (346-349).
A possibility for utilization of natural asphaltites, based on production of carbon adsorbents, was investigated. Various combinations of physical and chemical activation as well as demineralization procedures were used to obtain final products from natural asphaltites. Carbon adsorbents with developed pore structure and with alkaline character of the surface, as well as tar and gas products, were obtained by water vapor pyrolysis of natural asphaltites. The obtained carbon adsorbents show good adsorption properties; however, this performance is somewhat limited, probably due to their high mineral and sulfur content. It was established that hydropyrolysis is not appropriate method for production of carbon adsorbents on the base of asphaltites from Sirnak deposit due to the material coking. However, a two-stage process, including carbonization and subsequent activation, is appropriate for obtaining of carbon adsorbent with developed pore structure from Sirnak asphaltites. At the same time, hydropyrolysis is suitable for obtaining of activated carbon using asphaltites from Silopi deposit. Different oxygen groups were detected on the activated carbon surface, and their effect on surface properties of the samples was discussed.N2 adsorption isotherms at 77 K of AC from Sirnak asphaltites.Display Omitted
Keywords: Natural asphaltites; Activated carbon; Pyrolysis; Chemical activation; Water vapor activation;
Catalytic oxidative desulfurization systems based on Keggin phosphotungstate and metal-organic framework MIL-101 by Susana Ribeiro; André D.S. Barbosa; Ana C. Gomes; Martyn Pillinger; Isabel S. Gonçalves; Luís Cunha-Silva; Salete S. Balula (350-357).
The tetrabutylammonium salt of phosphotungstic acid, TBA3PW12O40 (PW12), has been encapsulated in the chromium terephthalate metal-organic framework MIL-101. Characterization of the composite PW12@MIL-101 by powder X-ray diffraction, FT-IR, FT-Raman and 31P magic-angle spinning (MAS) NMR spectroscopies confirmed that the structures of MIL-101 and the polyoxometalate anion were retained after immobilization. Both PW12 and the composite material were examined as catalysts in systems for the oxidative desulfurization (ODS) of model oils containing dibenzothiophene (DBT), 1-benzothiophene (1-BT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate was employed as both extractant and reaction medium. In a one-pot operation carried out at 50 °C, the BT derivatives in the model oils were extracted into the IL and then oxidized (using 30% H2O2 as oxidant) to form the corresponding sulfones, resulting in a continuous decrease in the sulfur content in the oil phase. The sulfur removal from the model oil with a sulfur content (for each BT derivative) of 500 ppm reached 100% within 1 h for DBT, 100% within 3 h for 1-BT, and 99% within 4 h for 4,6-DMDBT (sulfur content, 3–7 ppm). The ODS system containing the composite PW12@MIL-101 could be recycled three times with only a slight decrease in the catalytic performance.
Keywords: Oxidative desulfurization; Keggin-type polyoxometalate; Metal-organic framework; MIL-101; Benzothiophene derivatives;
Comparative study on the thermal reactivation of spent adsorbents by S. Román; B. Ledesma; A. Álvarez-Murillo; J.F. González (358-365).
Activated carbons previously used for p-Nitrophenol (PNP) adsorption were subjected to thermal reactivation in order to recover their initial porosity characteristics. Three activating agents were comparatively analysed (air, carbon dioxide and water steam).Regeneration results improved in the sequence air < CO2 < steam; steam activation almost removed all the adsorbate adsorbed on the carbon, achieving regeneration efficiency values up to 94% for N2 adsorption, and above 100% for PNP adsorption. The activation process did not cause a significant modification of the pore size distribution of the adsorbents, which remained microporous irrespective of the activating agent.The analysis of gases evolved was consistent with the chemical processes involved in the respective activations. There was a significant difference in the pattern followed by H2 in steam activations compared with CO2 and air. The prominence of water gas and water gas shift reactions were associated to this effect, which was also evident from the increase in CO and CO2 concentration.
Keywords: Regeneration; Activated carbons; Waste treatment; Physical activation;
Fly ash supported scandium triflate as an active recyclable solid acid catalyst for Friedel–Crafts acylation reaction by Ashu Rani; Chitralekha Khatri; Renu Hada (366-373).
Coal generated fly ash is converted into an efficient solid Lewis acid catalyst by loading scandium triflate on thermally and chemically activated fly ash. The activation of fly ash increased the surface silanol groups responsible for loading of scandium triflate species on fly ash surface. The physico-chemical properties of prepared fly ash supported scandium triflate (FST) catalyst were examined by XRD, FTIR, TEM and TGA analysis. The proposed model structure of FST shows that the triflate species withdraws the electron density from the scandium resulting in generating electron deficient Lewis acid sites on fly ash surface as confirmed by NH3 adsorbed FT-IR spectrum of FST catalyst. The catalyst showed higher activity for solvent free single pot Friedel–Crafts acylation of 2-methoxynaphthalene (2-MN) using acetic anhydride as an acylating agent achieving conversion up to 84% and selectivity of the desired product, 2-acetyle-6-methoxynaphthalene (6-AMN) up to 73%. 6-AMN is a precursor for anti-inflammatory drug, (S)-(+)-6-mathoxy-α-methyl-2-naphthaleneacetic acid, known as Naproxen. The stability of the catalyst was confirmed by hot filtration test. The catalyst could be easily regenerated and reused giving similar conversion up to three reaction cycles under similar experimental conditions. The work reports an alternative pathway for utilization of waste fly ash by using it in developing novel and cost effective, recyclable catalyst system for industrially important acylation reactions.
Keywords: Fly ash; Solid Lewis acid; Scandium triflate; Acylation;