Fuel Processing Technology (v.159, #C)
Editorial Board (IFC).
Recent developments in cokemaking technologies in Japan by Seiji Nomura (1-8).
Recently Japanese cokemaking industry have faced a lot of problems such as price increase and quality deterioration of metallurgical coal, coke oven aging and social demand for environmental contribution. To meet these challenges, Japan has developed various technologies, such as coal pre-treatment technology for utilizing low grade semi-soft coking coal (e.g. CMC, DAPS and SCOPE21), diagnosis and repair apparatus for coke oven chamber wall and a method to turn waste plastics into chemical raw materials using coke ovens. In this report, these progresses of cokemaking technology in Japan are reviewed.
Keywords: Coking coal; Coal pre-treatment; SCOPE21; Coke oven repair; Waste plastic recycling;
K2CO3-catalyzed steam gasification of ash-free coal char in a pressurized and vertically blown reactor. Influence of pressure on gasification rate and gas composition by Xuantao Wu; Jie Wang (9-18).
The K2CO3-catalyzed steam gasification of ash-free coal char was conducted in a pressurized and vertically blown reactor which was also characterized as a differential reactor. At a typical condition (total pressure, 0.5 MPa; steam partial pressure, 0.15 MPa; temperature, 750 °C; catalyst loading, 10%; superficial gas velocity, 55 cm s− 1), the gasification proceeded so fast that it was completed within 5 min. The dependence of either instantaneous gasification rate or average gasification rate on pressure was found to follow the Langmuir-Hinshelwood rate equation and the nth order rate equation, but the parameters for either rate equation varied with the carbon conversion. For a given coal char with a fixed catalyst loading, an overall kinetic model with the constancy of parameters is proposed to predict the gasification rate as a function of steam partial pressure, temperature and carbon conversion. While the elevation of steam partial pressure promoted the methanation mainly via the gas-char reaction, the yield of CH4 was negligible. The gas composition was not in the equilibrium of water gas shift reaction.
Keywords: Coal char; Pressure; Potassium carbonate; Steam gasification; Gas composition;
Improving hydrocarbon yield by two-step pyrolysis of pinewood in a fluidized-bed reactor by Huiyan Zhang; Shanshan Shao; Yang Jiang; Tharapong Vitidsant; Prasert Reubroycharoen; Rui Xiao (19-26).
Two-stage fast pyrolysis of pinewood, was investigated with and without catalysts in a fluidized-bed reactor. The method is using low-temperature pyrolysis (torrefaction) to remove unfavorable compounds firstly and then using high-temperature catalytic pyrolysis to produce hydrocarbons. The effects of torrefaction temperature, residence time and atmosphere on product distribution were investigated. The results show that the acidity of produced liquids reduced with increasing torrefaction temperature and residence time. Torrefaction pretreatment of pinewood reduced the yields of acetic acid and guaiacol effectively during catalytic pyrolysis. The highest aromatic yield was obtained with torrefied pinewood at 250 °C, which was boasted 30% of that without torrefaction. Besides, torrefied biomass can obviously reduce coke deposition on ZSM-5 in the catalytic pyrolysis process compared with raw pinewood. Therefore, the two-step pyrolysis can be considered as a more effective and promising method for producing high-quality liquid fuels and chemicals.
Keywords: Biomass; Torrefaction; Catalytic pyrolysis; Aromatics; Olefins; Fluidized-bed;
Extraction of direct coal liquefaction residue using dipropylamine as a CO2-triggered switchable solvent by Yu-Gao Wang; Ze-Shi Niu; Jun Shen; Lei Bai; Yan-Xia Niu; Xian-Yong Wei; Rui-Feng Li; Jun Zhang; Wen-Yi Zou (27-30).
Extracting polycyclic aromatic structures (PASs)-enriched portion from direct coal liquefaction residue (DCLR) with an energy-efficient way is significantly important for the effective utilization of DCLR. In the investigation, dipropylamine (DPA) with weak polarity was used to extract DCLR as a CO2-triggered switchable solvent. When the extract solution was triggered by CO2, the extract automatically precipitated with the yield of 22.8% of DCLR. Furthermore, adding proper amount of NaOH could successfully achieve the recovery of DPA, and the recovered solvent could be reused for extracting DCLR. According to the characterization results of the extract by multiple analytical tools, the extract mainly consisted of PASs with over 4 rings, and the average molecular model of aromatic cluster could be represented by the derivative of coronene with 8 substituent groups. The investigation proved that extraction of PASs-enriched portion using DPA from DCLR was feasible, and tremendous energetic and environmental benefits could be potentially gained given that the separation of extract and solvent as well as solvent recovery could be achieved by the non-thermal CO2-trigger.Display Omitted
Keywords: Direct coal liquefaction residue; CO2-triggered switchable solvent; Polycyclic aromatic structures; Structural characterization;
Effect of nickel on phosphorus modified HZSM-5 in catalytic cracking of butene and pentene by Jian-Wen Li; Tao Li; Hong-Fang Ma; Qi-Wen Sun; Wei-Yong Ying; Ding-Ye Fang (31-37).
Nickel was introduced into phosphorus modified HZSM-5 (P/HZSM-5) with different loadings by an impregnating method. The effect of nickel loading on the structure and acidity of catalysts was investigated by XRD, N2 adsorption, XPS, NMR, and FTIR of adsorbed pyridine. Nickel interacted with pre-introduced phosphorus, and the interaction promoted the migration of some phosphorus species from channels to external surface and broke part of the Al―O―P bonds. This increased the content of tetrahedral framework aluminum, and restored some Brønsted acid sites which were neutralized by phosphorus modification. In the cracking of butene and pentene, the performance of catalysts was strongly dependent on nickel content. For the cracking of butene, with increasing nickel content, butene conversion and ethylene selectivity increased, while propylene selectivity first increased, passed through a maximum and then decreased with further increment of nickel content; for the cracking of pentene, with increasing nickel content, pentene conversion, ethylene selectivity and propylene selectivity increased.
Keywords: Butene; Pentene; Catalytic cracking; Modified HZSM-5;
Analytical prediction of coal spontaneous combustion tendency: Velocity range with high possibility of self-ignition by Qi Lin; Shugang Wang; Yuntao Liang; Shuanglin Song; Tingxiang Ren (38-47).
Coal spontaneous combustion is an inherent problem in coal mines throughout the world. The analysis of stationary-states, including stable point and critical point, is an effective method to judge its ignition tendency. A lower critical point temperature means that it is more likely to cause fire. In the past, due to the limitation of mathematical methods, the consumption and distribution of oxygen concentration are usually neglected. In order to accurately analyze coal ignition tendency, this paper takes coal bulk as a porous system and develops an improved model by a combination of oxygen species and energy equation. The model is solved for stationary-states of the system. Qualitative analysis of the stationary-states gives a mechanism explanation for the reason why coal spontaneous ignition is hard to be extinguished and indicates that the temperature of initial endpoint and that of internal site can be uniquely determined from each other. It further points out a trend that the location of critical point moves inward as the inlet air velocity increases, which correlates well with simulation results of the existing literatures. Then, for stationary-states, calculation results of Killoch 6015 coal are obtained. Quantitative analysis of them finds a trend that the temperature of critical point rises rapidly after its slow increase. At last, a velocity range, in which the possibility of fire is extremely high, is presented by simulation computation, e.g., the range of Killoch 6015 coal is determined as 8 × 10− 5–3 × 10− 3 m/s when the critical ignition temperature is set as 150 °C.
Keywords: Analytical solution; Velocity range; Critical temperature; Coal spontaneous combustion;
Effects of gasification temperature and atmosphere on char structural evolution and AAEM retention during the gasification of Loy Yang brown coal by Tingting Li; Lei Zhang; Li Dong; Shu Zhang; Penghua Qiu; Shuai Wang; Chun-Zhu Li (48-54).
This study aims to investigate the influence of gasification temperature on the evolution of char structure and the retention of alkali and alkaline earth metallic (AAEM) species for a Victorian brown coal. The experiments were carried out at 800, 850 and 900 °C in pure CO2, 15% H2O balanced with Ar and 15% H2O balanced with CO2 in a one-stage fluidised-bed/fixed-bed reactor. FT-Raman spectroscopy was used to characterise the structural features of the chars obtained at varying conversion levels during gasification. The concentrations of AAEM species in the chars left after gasification were quantified with inductively coupled plasma – optical emission spectroscopy. The specific char-O2 reactivity of the gasified char was measured in a thermogravimetric analyser. The results show that the CO2 and H2O partly compete for the active sites on the char. The increasing total Raman area caused by the formation of O-containing structures in char does not appear to be the only factor determining the char gasification rate in H2O-containing atmospheres. With increasing temperature, CO2 plays an increasingly more important role in the char evolution and subsequently influences the AAEM retention in char from the gas mixture. The gasification temperature does not change the individual reaction pathway for char-CO2 or char-H2O reaction within temperature range investigated.
Keywords: Gasification; Char structure; AAEM retention; Loy Yang brown coal; FT-Raman spectroscopy;
Effect of mesoporosity of bimetallic Ni-Ru-Al2O3 catalysts for hydrogen production during supercritical water gasification of glucose by Md Zakir Hossain; Muhammad B.I. Chowdhury; Qasem Alsharari; Anil Kumar Jhawar; Paul A. Charpentier (55-66).
A well-known problem with metal supported alumina catalysts during gasification processes for H2 formation is catalyst deactivation by coke formation and pore plugging. Poorly controlled catalyst structure with low surface area and microporous structure also accounts for low catalyst activity. This work investigated bimetallic Ni-Ru/Al2O3 catalysts that are both effective and durable for glucose gasification in supercritical water with minimal coke formation. Both non-ionic (Pluronic P-123) and cationic (CTAB) templates were examined for mesoporous alumina synthesis with Ni and Ru loadings and compared with a conventional incipient impregnation method. Gas formation during SCWG catalysis was monitored for hydrogen formation while the catalysts were examined both before and after reaction by a variety of physico-chemical techniques including BET surface area, BJH pore size analysis, XRD, TG-DTA, TPR, TPO, Raman spectroscopy & TEM microscopy. The results showed that templating helped disperse both Ni and Ru particles homogeneously inside the pores of mesoporous Al2O3 catalysts; whereas the impregnated catalyst gave poorer dispersion. Comparing with the impregnation method, a six-fold increase of BET surface area was observed using the one-pot synthesis method. Hydrogen production during glucose gasification increased by 25 mol% for both templated catalysts, with the CTAB catalyst showing slightly higher activity. This method provided insignificant coke deposition indicating that the new Ru-Ni/Al2O3 templated catalyst is promising for the development of hydrogen production for an emerging biorefinery.Display Omitted
Keywords: Mesoporous; Catalyst; Sol-gel synthesis; Supercritical water; Gasification; Hydrogen production; Coke deposition;
Some factors influencing the fluidity of coal blends: Particle size, blend ratio and inherent oxygen species by Yuuki Mochizuki; Ryo Naganuma; Kazuya Uebo; Naoto Tsubouchi (67-75).
The fluidity performance of blended coals prepared from caking coal and non- or slightly-caking coal of different particle sizes, and the evolution of gaseous oxygen containing compounds (CO, CO2 and H2O) during carbonization are examined using the Gieseler plastometer method, and a flow-type fixed-bed quartz made reactor, respectively. The heating rate and temperature are 3 °C/min and 1000 °C, respectively. The Gieseler fluidity decreases with increasing blend ratio of non- or slightly-caking coal to caking coal. In addition, the fluidity tends to decrease with the decreasing particle size of non- or slightly-caking coal in blended coals. The evolution of CO, CO2 and H2O during the carbonization of single coals begins at 200–400 °C, and the main peak of the formation rate appears at 450–700 °C. The amount of gaseous O-containing compounds evolved until 1000 °C from the non- or slightly-caking coals is greater than that of evolved from the caking coal. Additionally, a negative correlation is observed between the amounts of CO, CO2, and H2O that evolve up to the initial softening temperature and the maximum fluidity value. The profiles of formation rates of the three gaseous O-containing compounds from the blended coal during carbonization are different with additive average based on the results of single coals. Furthermore, for the blended coal, the starting temperature H2O evolution measured shifts to higher temperature in comparison with that of calculated based on the results of single coals. Therefore, it is possible that the H2O produced from non- or slightly-caking coal in blended coal or that the H2O formation reactions in blended coal during carbonization affects the fluidity performance of the blended coal.
Keywords: Caking coal; Non- or slightly-caking coal; Blend coal; Fluidity; Gaseous oxygen containing compounds; Particle size; Blend ratio;
Catalytic performance of CoMo catalysts supported on mesoporous ZSM-5 zeolite-alumina composites in the hydrodesulfurization of 4,6-dimethyldibenzothiophene by Quanyong Yu; Lei Zhang; Rong Guo; Jin Sun; Wenqian Fu; Ting Tang; Tiandi Tang (76-87).
Composite materials (AZ-M-x) were prepared by mechanically mixing the mesoporous zeolite ZSM-5 (MZSM-5) and γ-Al2O3. This composite was employed as a support for CoMo catalysts (CoMoS/AZ-M-x). The CoMoS/AZ-M-x catalysts show high activity (TOF = 2.1–3.0 × 10− 3 s− 1) in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) as compared to the CoMo catalyst supported on γ-Al2O3 (CoMoS/γ-Al2O3, TOF = 1.9 × 10− 4 s− 1), and the HDS activity increased with the MZSM-5 content in the composites. In contrast, the HDS activity of a mixture of microporous ZSM-5 with γ-Al2O3 supported CoMo catalyst is similar to that of the CoMoS/γ-Al2O3 catalyst. Compared with microporous ZSM-5, introducing MZSM-5 into γ-Al2O3 improves the mesoporous structure of the composites, which benefits mass transfer of the reactant molecules. Furthermore, MZSM-5 in the composites modifies their surface properties with abundant acidic hydroxyl groups, which can weaken the Mo-support interaction, leading to modifications in the morphology of the MoS2 phases to form multi-stacked MoS2 active phases on the CoMoS/AZ-M-x catalysts.Display Omitted
Keywords: Mesoporous zeolite ZSM-5; Composite materials; Hydrodesulfurization; 4,6-Dimethyldibenzothiophene;
Thermochemical study of the briquetting process of mattress foams by María A. Garrido; Rafael Font; Juan A. Conesa (88-95).
The production of flexible polyurethane foam (FPUF) briquettes has been tested at four different temperatures (160, 170, 180 and 190 °C) and with four different compacting pressures (17, 24, 35 and 48 MPa), selecting 180 °C and 35 MPa as the best briquetting conditions. In addition, heterogeneous briquettes have been moulded employing 10, 18 and 25% of viscoelastic memory foam (VMF) with FPUF and the same proportions for latex foam (LATEX) with FPUF, at 180 °C and 24 and 35 MPa of compacting pressure. For VMF + FPUF briquettes mixtures of up to 18% of VMF showed high quality, whereas this proportion decreased by up to 10% for LATEX. The FTIR and TG-IR analyses were conducted to investigate the mechanism of adhesion bonding in heterogeneous briquettes considering that the FPUF acted as a binder. The temperature (180 °C) and pressure (35 MPa) selected to mould the heterogeneous briquettes seem to be enough to achieve the break of part of the urethane bond present in the FPUF improving the mobility of long polymeric chains which allowed the bonding of different materials.Display Omitted
Keywords: Flexible polyurethane foam; Viscoelastic memory foam; Latex foam; Briquette, FTIR analysis, TG-IR analysis;
Extraction of aromatic hydrocarbons from pyrolysis gasoline using tetrathiocyanatocobaltate-based ionic liquids: Experimental study and simulation by Marcos Larriba; Pablo Navarro; Noemí Delgado-Mellado; Victor Stanisci; Julián García; Francisco Rodríguez (96-110).
The pyrolysis gasoline is one of the main sources of aromatic hydrocarbons as a result of their high content in these compounds. Organic solvents such as sulfolane are currently employed in the extraction of aromatic but the ionic liquids (ILs) have been recently proposed as potential replacement. In this work, we have studied the use of the bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate ([emim]2[Co(SCN)4]) and bis(1-butyl-3-methylimidazolium) tetrathiocyanatocobaltate ([bmim]2[Co(SCN)4]) ILs in the extraction of aromatic hydrocarbons from pyrolysis gasoline. The extractive properties of both tetrathiocyanatocobaltate-based ILs were compared to those of other promising ILs and sulfolane, showing the highest values. To perform the simulation of the whole process, we have experimentally studied the liquid-liquid extraction of aromatics from pyrolysis gasoline and the recovery of the extracted hydrocarbons from the ILs. In addition, a thermophysical characterization of the ionic solvents was performed measuring their densities, viscosities, thermal stabilities, maximum operation temperatures, and specific heats. Employing the experimental data, the extractor was simulated using the Kremser equation whereas the recovery section formed by flash distillation units was simulated using a new algorithm specifically design to the case of a high concentration of non-volatile compounds.
Keywords: Aromatic/aliphatic separation; Ionic liquids; Liquid–liquid extraction; Vapor-liquid separation; Thermophysical characterization; Process simulation;
Catalytic etherification of bioglycerol with bioethanol over H-Beta, H-Y and H-MOR zeolites by Dušan Mravec; Andrej Turan; Adriána Filková; Natália Mikesková; Enikö Volkovicsová; György Onyestyák; Szabolcs Harnos; Ferenc Lónyi; Jozsef Valyon; Alexander Kaszonyi (111-117).
Etherification of glycerol with ethanol, both from renewable resources, was studied over heterogeneous catalysts (zeolites of the type BEA, MOR and FAU) and ion-exchange resin Amberlyst 35. The best results were obtained with zeolite H-Beta (CP 814 Q) with the ratio Si/Al = 25. The conversion of glycerol at the temperature of 200 °C was 51,7% at mono-ethyl ethers selectivity of 62% and di- + tri-ethyl ether selectivity of 37,7%. The conversion of glycerol, which was obtained by purification of glycerol phase from MERO production (methyl esters of acids from rape-seed oil), at the same conditions was 50,8%, selectivity to mono-ethers was 71,8% and to di- + tri- ethers 28,1%. Ethers of glycerol have utilization as oxygenate additives to fuels and have positive effect on decreasing particulate matters and carbonyl compounds in exhaust gases.Display Omitted
Keywords: Glycerol; Ethyl ethers of glycerol; Zeolites; Oxygenate additives to fuels;
Influence mechanism of zinc on the solution loss reaction of coke used in blast furnace by Wei Wang; Jie Wang; Runsheng Xu; Yue Yu; Yan Jin; Zhengliang Xue (118-127).
The influence mechanism of zinc on the solution loss reaction of coke at high temperature was studied using the method of liquid phase adsorption. The microcrystalline structure, pore structure, micro morphology and optical texture of coke were analyzed by X-Ray diffraction (XRD), BET, scanning electron microscopy (SEM) and optical microscopy in present research. The results show that zinc can increase the coke reactivity index (CRI) and decrease the coke strength after reaction (CSR). Furthermore, the CRI is the highest, as well as the CSR is lowest and the coke structure is severely damaged when the enriched zinc content in coke reaches to 1.17%. The results of XRD and polarizing microscopy show that the zinc catalysis on the solution loss reaction of anisotropic texture with higher degree of graphitization is larger than that of the isotropic texture. Combined with BET and optical panorama, it can be reveals that zinc can promote the generation and combination of coke pores during its catalysis process on gasification reaction, resulting in the increase of specific surface area and volume of micropores, which in turn provides favorable conditions for the permeation of zinc vapor and the kinetics condition of gasification reaction, thereby the reaction is further intensified. Meanwhile, large connected pores and honeycomb cavern caused by catalysis reduce the coke strength greatly. A compound phase containing zinc was not found in the reacted Zn-enrich coke after careful inspection through SEM/EDS and XRD, which reveals that the catalysis is derived from zinc. The zinc catalysis on the solution loss reaction of coke is mainly attributed to accelerating the decomposition of the ketone group, promoting the formation of CO gas.
Keywords: Zinc; Coke; Solution loss reaction; Coke strength; Catalysis; Influence mechanism;
Chemical equilibrium analysis of hydrogen production from shale gas using sorption enhanced chemical looping steam reforming by Zainab Ibrahim S G Adiya; Valerie Dupont; Tariq Mahmud (128-144).
Detailed chemical equilibrium analysis based on minimisation of Gibbs Energy is conducted to illustrate the benefits of integrating sorption enhancement (SE) and chemical looping (CL) together with the conventional catalytic steam reforming (C-SR) process for hydrogen production from a typical shale gas feedstock. CaO(S) was chosen as the CO2 sorbent and Ni/NiO is the oxygen transfer material (OTM) doubling as steam reforming catalyst. Up to 49% and 52% rise in H2 yield and purity respectively were achieved with SE-CLSR with a lower enthalpy change compared to C-SR at S:C 3 and 800 K. A minimum energy of 159 kJ was required to produce 1 mol of H2 at S:C 3 and 800 K in C-SR process, this significantly dropped to 34 kJ/mol of produced H2 in the CaO(S)/NiO system at same operating condition without regeneration of the sorbent, when the energy of regenerating the sorbent at 1170 K was included, the enthalpy rose to 92 kJ/mol H2, i.e., significantly lower than the Ca-free system. The presence of inert bed materials in the reactor bed such as catalyst support or degraded CO2 sorbent introduced a very substantial heating burden to bring these materials from reforming temperature to sorbent regeneration temperature or to Ni oxidation temperature. The choice of S:C ratio in conditions of excess steam represents a compromise between the higher H2 yield and purity and lower risk of coking, balanced by the increased enthalpy cost of raising excess steam.Display Omitted
Keywords: Shale gas; Steam reforming; Chemical looping; Sorption enhancement;
Simultaneous desulfurization and denitrification through an integrative process utilizing NaClO2/Na2S2O8 by Runlong Hao; Shuo Yang; Bo Yuan; Yi Zhao (145-152).
SO2 and NO emitted from coal-fired power plants have caused serious air pollution in China. In this paper, a novel complex oxidant, NaClO2/Na2S2O8, was prepared for simultaneous removal of SO2 and NO through a pre-oxidation method. The cooperative effect as well as mechanism between NaClO2 and Na2S2O8 was elucidated, with the corresponding best ratio of 4 wt%:4 wt%. The effects of various reaction factors on the simultaneous removal were investigated, i.e. the adding rate of the complex oxidant, the pH of the complex oxidant, the reaction temperature, the flue gas residence time and the coexistence gases. The experimental results indicated that the desulfurization process was mainly controlled by the sodium humate (HA-Na) absorption, while the denitrification was significantly affected by various conditions. Under the optimal conditions, the removal efficiencies for SO2 and NO were 100% and 82.7%, respectively. Compared with our previous works, NaClO2/Na2S2O8 has some superiorities of less dosage of the complex oxidant, rapid reaction rate and more efficient in NO removal. According to the characterizations of removal products by XRD, FT-IR and UV–Vis, and the literature references, the reaction mechanism was speculated.
Keywords: Desulfurization; Denitrification; NaClO2; Na2S2O8; Reaction mechanism;
Study on the preheating stage of low rank coals liquefaction: Product distribution, chemical structural change of coal and hydrogen transfer by Pan Hao; Zong-Qing Bai; Zhi-Tong Zhao; Jing-Chong Yan; Xiao Li; Zhen-Xing Guo; Jun-Li Xu; Jin Bai; Wen Li (153-159).
Preheating stage of direct liquefaction of Yunnan lignite (YN) and Hami sub-bituminous coal (HM) in tetralin at temperature range of 200–350 °C was investigated under nitrogen atmosphere. In order to reveal the product characteristics and hydrogen transfer between coal and solvent during preheating process, thermo-gravimetric analyzer coupled with mass spectrometer (TG–MS), X-ray photoelectron spectroscopy (XPS) and gas chromatography coupled with mass spectrometer (GC–MS) were employed. The results show that yields of light products, i.e., oil, gas, and water, increase with raising temperature during the preheating process. YN and HM achieve 51.69% and 44.19% (daf) light products yields at 350 °C, respectively. Moreover, oxygen-containing functional groups, such as carboxyl, ethers, and alcohols in raw coal are reduced after preheating. In addition, hydrogen transfer achieves a perceptible extent even at 200 °C and the amount of transferred hydrogen increases with raising temperature. A positive dependence of hydrogen transfer on conversion is observed during preheating stage. Comparing the two coal samples, YN obtains higher conversion and hydrogen transfer due to its higher thermal reactivity at this temperature range. However, HM achieves higher oil yield than YN does at 350 °C since high hydrogen transfer amount and H/C ratio of raw coal promote the oil yield.
Keywords: Low rank coal; Preheating stage; Product distribution; Hydrogen transfer;
In-situ catalytic pyrolysis of peanut shells using modified natural zeolite by L.I. Gurevich Messina; P.R. Bonelli; A.L. Cukierman (160-167).
In-situ catalytic pyrolysis of peanut (Arachis hypogaea) shells was investigated employing modified clinoptilolite. Likewise, conventional pyrolysis of the shells was explored to quantify the deoxygenation degree of bio-oil. Two solid catalysts obtained from natural clinoptilolite were used: one which retained most of the native cations and another one subjected to ion exchange treatment to develop Brønsted acid sites. These catalysts were characterized using different techniques, such as scanning electron microscopy with X-ray microanalysis, Fourier transform infrared spectroscopy by pyridine adsorption, and nitrogen sorptometry. Assays in a bench scale installation based on a fixed bed reactor were conducted at 500 °C and the yields of the three kinds of pyrolysis products (bio-oil, bio-char and gases) were determined. Likewise, the composition and other physical properties of the bio-oil and gases were investigated. Both catalysts led to reduce the oxygen content of the bio-oil, improving its high heating value. On the other hand, catalytic pyrolysis promoted a slight reduction in bio-oil production at expenses of an increase in gases generation. The catalyst subjected to ion exchange performed better than the native form as less water was generated in the catalytic cracking.
Keywords: Catalytic pyrolysis; Peanut shells; Clinoptilolite; Bio-oil quality improvement;
High-performance HZSM-5/cordierite monolithic catalyst for methanol to propylene reaction: A combined experimental and modelling study by Xun Huang; Xue-Gang Li; Hu Li; Wen-De Xiao (168-177).
Methanol to propylene (MTP) reaction system over HZSM-5 zeolites is characterized by obvious consecutive side reactions to paraffin and aromatics, which practically gives rise to a low propylene yield. In this work, HZSM-5/cordierite monolithic honeycomb catalyst was prepared by washcoating method and investigated in a lab fixed-bed reactor. Compared to the traditional extrudes, the monolithic honeycomb accelerated methanol conversion rate by 2.78 and 6.66 times when methanol was fed alone and co-fed with butene, respectively, and reduced the output of paraffin and aromatics by 90% when methanol was co-fed with butene. A two-dimensional mathematic model was then developed to simulate the HZSM-5/cordierite catalyst and validated by experimental data. On the basis of a commercial configuration of MTP reactor, a six-stage adiabatic fixed-bed reactor was simulated with ethylene and C4–C6 olefins recycled, the calculated space velocity and propylene selectivity for monolithic catalyst can be as high as 5.27 gMeOH/gcat/h and 81.6%, with significant enhancement achieved compared to the conventional catalyst with the results of 0.741 and 62.6%, respectively.
Keywords: Monolithic catalyst; ZSM-5; Methanol to propylene; Reactor modelling;
Evolution of char structure during mengdong coal pyrolysis: Influence of temperature and K2CO3 by Junhao Hu; Yingquan Chen; Kezhen Qian; Zixu Yang; Haiping Yang; Yang Li; Hanping Chen (178-186).
Weight loss and gas release behavior of mengdong coal (MD) during pyrolysis was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and char evolution of coal chars derived at different pyrolysis temperature were analyzed with two dimensional perturbation correlation infrared spectroscopy (2D-PCIS) method to reveal the mechanism of mengdong coal pyrolysis. The MD coal showed a significant weight loss at 300– 600 °C during pyrolysis. Free OH groups reacted before OH-πand self-associated n-mers hydrogen bond. The demethylenation reaction sequence was aliphatic R3-CH groups and asymmetric aliphatic R-CH3 > symmetric aliphatic R2-CH2 > asymmetric aliphatic R2-CH2. CO2 releasing mainly resulted from the crack of C―O in aryl ethers groups, C―O in alcohols in coal molecular. The effect of K2CO3 on char structure was also studied. The results showed that, inherent mineral of coal presented stronger catalytic effects towards pyrolysis. K2CO3 addition influenced the reaction sequences of R3-CH, symmetric R2-CH2 and asymmetric R2-CH2 insignificantly, but could significantly change the correlation of C―O, C ＝O, CH―CH3, and aromatic C ＝C bond.
Keywords: Mengdong coal; Pyrolysis; Char evolution; Mineral; Deashing; K2CO3;
Corrosion of stainless steels in the riser during co-processing of bio-oils in a fluid catalytic cracking pilot plant by M.P. Brady; J.R. Keiser; D.N. Leonard; A.H. Zacher; K.J. Bryden; G.D. Weatherbee (187-199).
Co-processing of bio-oils with conventional petroleum-based feedstocks is an attractive initial option to make use of renewable biomass as a fuel source while leveraging existing refinery infrastructures. However, bio-oils and their processing intermediates have high concentrations of organic oxygenates, which, among their other negative qualities, can result in increased corrosion issues. A range of stainless steel alloys (409, 410, 304L, 316L, 317L, and 201) was exposed at the base of the riser in a fluid catalytic cracking pilot plant while co-processing vacuum gas oil with pine-derived pyrolysis bio-oils that had been catalytically hydrodeoxygenated to ~ 2 to 28% oxygen. A catalyst temperature of 704 °C, a reaction exit temperature of 520 °C, and total co-processing run times of 57–75 h were studied. External oxide scaling 5–30 μm thick and internal attack 1–5 μm deep were observed in these short-duration exposures. The greatest extent of internal attack was observed for co-processing with the least stabilized bio-oil, and more so for types 409, 410, 304L, 316L, 317L stainless steel than for type 201. The internal attack involved porous Cr-rich oxide formation, associated with local Ni-metal enrichment and S-rich nanoparticles, primarily containing Cr or Mn. Implications for alloy selection and corrosion are discussed.
Keywords: Stainless steel; Corrosion; Bio-oil; Biomass; Co-processing; Fluid catalytic cracking;
Analysis of the effects of diesel/methane dual fuel combustion on nitrogen oxides and particle formation through optical investigation in a real engine by Silvana Di Iorio; Agnese Magno; Ezio Mancaruso; Bianca Maria Vaglieco (200-210).
Great attention was paid to nitrogen oxides and particulate matter emitted by the compression ignition engines. The adoption of methane dual fuelled with diesel could contribute to the reduction of these pollutants.This paper aims to investigate the combustion phenomena occurring when a premixed methane/air charge is ignited by the direct injection of diesel fuel. The research activity was performed on a production compression ignition engine, three-cylinder, 1.0 L, equipped with a common rail injection system. In order to operate in diesel/methane dual fuel mode, the intake manifold of the engine was modified to set an electronic port fuel injector suitable for gaseous fuels. Different engine speeds and loads were tested. For each engine condition, a small part of the total energy was provided by the direct injected diesel fuel while the remaining by the methane. Thermodynamics analysis of the combustion process was performed through conventional measurement involving in-cylinder pressure acquisition. Endoscope based optical techniques were carried out for the combustion visualization with high spatial distribution and temporal evolution. Two-colour pyrometry method was applied to the flame images to evaluate the temperature and the soot concentration. This method allows to achieve a better insight about the pollutant formation. Experimental results revealed that DF combustion occurs with lower temperature and soot formation than diesel operation thus leading to lower nitrogen oxides and particle emissions at exhaust.
Keywords: Dual-fuel engine; Methane; Two-colour pyrometry; NOx emissions; Particle emissions;
Effects of thermal pretreatment and ex-situ grinding on the pyrolysis of mallee wood cylinders by Shengjuan Jiang; Xun Hu; Xin Shao; Yao Song; Daohong Xia; Chun-Zhu Li (211-221).
This study investigated the effects of thermal pretreatment and ex-situ grinding on the production of bio-oil and biochar from the pyrolysis of mallee wood cylinders in a fluidised-bed reactor. The wood cylinders were firstly pretreated at 150–380 °C and were then crushed into small particles before further pyrolysis at 500 °C. Thermal pretreatment alone for wood cylinders could not promote the bio-oil yield. Combined thermal pretreatment at low temperatures and subsequent grinding facilitated the formation of bio-oil and minimised the formation of biochar. This is because the thermal pretreatment and grinding partially destroyed the cell wall structure and improved the mass transfer of volatiles exiting from the particles during the subsequent pyrolysis. However, if the pretreatment temperature was above 260 °C, the biochar yields increased due to the cross-linking and charring reactions. These charring reactions compromised the beneficial effects of grinding, leading to decreases in the formation of bio-oil. The balance between thermal pretreatment and grinding needed to be delicately managed to maximise the formation of bio-oil. The pretreatment temperature would significantly affect the composition of bio-oil from the ex-situ grinding pyrolysis. The controlled pretreatment temperature could somewhat “activate” lignin or cause cross-linked bonds in biomass which was responsible for the formation of aromatics.
Keywords: Bio-oil; Biochar; Thermal pretreatment; Grinding; Pyrolysis; Wood cylinders;
Photocatalytic oxidation removal of Hg0 by ternary Ag@AgCl/Ag2CO3 hybrid under fluorescent light by Anchao Zhang; Lixiang Zhang; Qifeng Zhu; Bingjie Dai; Wei Sheng; Sheng Su; Jun Xiang (222-231).
Photocatalytic oxidation removal of elemental mercury (Hg0) by Ag@AgCl/Ag2CO3 hybrids was carried out in a wet scrubbing reactor under fluorescent light. The photocatalysts synthesized via a modified coprecipitation method were characterized by using SEM-EDS, HRTEM, N2 adsorption-desorption, XRD, XPS, DRS, and ESR. Effects of operational parameters on Hg0 removal, including AgCl content, fluorescent light (FSL) irradiation, pH value, reaction temperature, and flue gas components (O2, SO2 and NO) were studied in detail. Furthermore, simultaneous removal of Hg0 and SO2 was investigated and the possible mechanism of highly enhanced Hg0 removal efficiency was proposed. The results showed that AgCl amount, fluorescent light irradiation, reaction temperature, SO2 and NO had notable impact on Hg0 removal efficiency. Simultaneous removal efficiencies of 98% for SO2 and 80% for Hg0 were obtained by coupling Ag@AgCl(0.3)/Ag2CO3 with Ca(OH)2 under FSL. The trapping studies of reactive radicals exhibited that holes (h+) were one of the main reactive species for Hg0 removal.Display Omitted
Keywords: Photocatalytic oxidation; Hg0 removal; Ternary Ag@AgCl/Ag2CO3 photocatalysts; Fluorescent light;
Insights into individual and combined effects of phosphorus and EDTA on performance of NiMo/MesoAl2O3 catalyst for hydrotreating of heavy gas oil by Sandeep Badoga; Ajay K. Dalai; John Adjaye; Yongfeng Hu (232-246).
The individual and combined effects of phosphorus, EDTA and support modification on hydrotreating of bitumen derived heavy gas oil were studied. The EDTA/Ni molar ratio was varied from 0.5 to 2 for optimization and studying the effect of EDTA on activity of mesoporous alumina supported NiMo catalyst. The phosphorus was impregnated using two different methods: modified co-impregnation (MCI) and sequential impregnation (SI), and their effect on physico-chemical properties was studied. The catalysts were characterized using N2-physisorption, CO-chemisorption, pyridine-FTIR, H2-TPR, NH3-TPD, X-ray diffraction, High resolution-TEM and XANES. HRTEM and XANES techniques were predominantly used to determine the structural changes, and to visualize and measure active metal dispersion. All catalysts were tested for hydrotreating reactions in a continuous trickle-bed reactor at industrial conditions. The activities were measured in terms of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDA). The studies on NiMo/γ-Al2O3 were also performed for comparison purpose. The increase in HDS and HDN activities was observed for NiMo/MesoAl2O3 catalyst and this is assigned to high metal dispersion due to large surface area and pore volume of synthesized mesoporous alumina. The addition of EDTA in NiMo/MesoAl2O3 catalyst resulted in increasing the MoS2 slab length and stacking degree, which resulted in decrease in dispersion, and HDN and HDS activities. However, the catalyst NiMoP/MesoAl2O3(MCI) containing only 2.5 wt.% P prepared by modified co-impregnation method showed the best HDS (97 wt.%) and HDN (77 wt.%) activity among all other studied catalysts. This increase in activity is attributed to the effect of mesoporous alumina and influence of P on reducibility, acidic strength, structural changes and desired molybdenum dispersion.Display Omitted
Keywords: Mesoporous alumina; EDTA; Phosphorus; XANES; Hydrotreating; HGO;
Valorisation of rice husks using a TORBED® combustion process by R Blissett; R Sommerville; N Rowson; J Jones; B Laughlin (247-255).
World production of rice exceeds 750 million tonnes per year of which a fifth is removed in the form of rice husk during the milling process. The use of rice husks as a source of sustainable and renewable energy is often hindered by lack of capital and a poor understanding of rice husk combustion characteristics. This results in the selection of poor quality technology which generates significant quantities of harmful crystalline silica waste. Despite previous work in the area, detailed characterisation of the combustion of rice husk ash in a TORBED reactor across a wide temperature range has not yet been attempted and little effort has been directed towards assessing the economic viability of generating quality rice husk ashes. The use of a TORBED reactor enables low residual carbon after combustion without the generation of harmful crystalline material. Rice husk was combusted in a 400 mm reactor at temperatures between 700 and 950 °C. In the subsequent characterisation studies the resulting materials were shown to be fully amorphous high purity silica (> 95%) and were readily digested in a series of alkaline digestion experiments. Complete silica conversion was only possible using uneconomic Na2O/SiO2 ratios and further optimisation of the combustion process to generate higher surface area material is necessary to increase the digestion rates further. Provisional economic analysis suggests that sales of the by-product enhance the returns from rice husk based power generation. TORBED reactors enable the combustion of rice husk with considerable operating flexibility and they generate products that could be used to displace resource intensive products and processes thus, added value from the by-products can be obtained by using TORBED reactor technology.
Extension of the chemical percolation devolatilization model for predicting formation of tar compounds as soot precursor in coal gasification by Satoshi Umemoto; Shiro Kajitani; Kouichi Miura; Hiroaki Watanabe; Motoaki Kawase (256-265).
This paper proposed and validated a new coal devolatilization model that can predict yields of respective gas and tar components, and be directly coupled with an elementary step-like reaction model. The new model was an extension of the chemical percolation devolatilization (CPD) model. The CPD model is one of the existing primary pyrolysis models that consider the coal chemical structure. The mole fraction of labile bridges, cross links, peripheral groups, and average molecular weight of monomer in coals examined in this study were determined by a 13C NMR analysis. The aromatic ring clusters size distribution was determined by a coal pyrolysis test using a Curie point pyrolyzer. The thermal decomposition process of the coal chemical structure was expressed by nine elementary reactions. From the above, the extended CPD model can predict gas and tar components as respective chemical species (H2O, CO2, CO, CH4, benzene, naphthalene and phenanthrene) and consequently capture the secondary decomposition and polymerization in gas phase by coupling the detailed gas-phase chemistry. The proposed model was validated by comparing with experiments using a pressurized drop tube furnace (PDTF). The results showed that the trend of light gases and soot yield in the experiments could be successfully reproduced by the extended CPD model.
Keywords: Coal gasification; Pyrolysis model; Soot; PAH; CPD model;
Heterogeneous reaction kinetics of mercury oxidation by HCl over Fe2O3 surface by Yingju Yang; Jing Liu; Zhen Wang; Feng Liu (266-271).
Fe2O3 is one of the catalytically active compositions present in fly ash for mercury oxidation. Fe2O3 sample was prepared by a precipitation method. The textural property and surface chemical state of Fe2O3 sample were characterized by Brunauer-Emmett-Teller (BET) surface area and X-ray photoelectron spectroscopy (XPS), respectively. A series of experiments were conducted in a fixed-bed reactor to investigate the heterogeneous mercury oxidation by HCl on Fe2O3 surface. Fe2O3 can obtain a maximum mercury oxidation efficiency of 89.5% at 100 °C. Heterogeneous Hg0 oxidation by HCl over Fe2O3 surface occurs through the gas-solid reaction between gas-phase Hg0 and active surface chlorine species generated from the dissociation of HCl. Based on the experimental results, a detailed eight-step heterogeneous reaction kinetic model of mercury oxidation over Fe2O3 was proposed to predict mercury oxidation in the presence of Fe2O3 and HCl. This heterogeneous model was validated by comparison to different experimental data. The results of kinetic calculations show that model prediction is in good agreement with experimental results obtained by two research groups. Mercury oxidation process over Fe2O3 surface can be described using this heterogeneous kinetic model.
Keywords: Mercury oxidation; Heterogeneous kinetic model; Kinetic calculations; Fe2O3;
Development of methods improving storage stability of bitumen modified with ground tire rubber: A review by Maciej Sienkiewicz; Kaja Borzędowska-Labuda; Artur Wojtkiewicz; Helena Janik (272-279).
The following paper presents an overview of methods for improving the storage stability at high temperature of rubber modified bitumen. The storage stability of the rubber modified bitumen can be improved by using a various types of modifiers that form the bonds between the components of these binders. The increase in stability can also be achieved by using crumb rubber surface-activated by furaldehyde or ground tire rubber (GTR) treated by gamma irradiation or modified by devulcanization process. The storage stability of rubber modified bitumen can be also improved by preparing compositions obtained from GTR and other components leading to a reduction in density as compared to unmodified GTR. unmodified GTR.
Keywords: Rubber modified bitumen; Storage stability; Ground tire rubber(GTR);
One-pot production of 5-hydroxymethylfurfural from cellulose using solid acid catalysts by Hisakazu Shirai; Saki Ikeda; Eika W. Qian (280-286).
5-Hydroxymethylfurfural (HMF) is one of the most important intermediate platforms for production of both chemicals and liquid fuel derived from biomass. The one-pot production of HMF from cellulose was conducted in a batch reactor in the presence of various solid acid catalysts. The prepared catalysts were characterized by means of Brunauer–Emmett–Teller measurement and pyridine adsorption FT-IR to investigate their pore structure and acidic properties. The presence of gaseous hydrogen enhanced the formation of HMF by suppressing the formation of byproducts. Increasing the acid amount of the catalyst caused an increase in the conversion and selectivity for organic acid and a decrease in the HMF selectivity. A Brønsted-type catalyst (Al-SBA-15) favored the formation of HMF. The reaction conditions of 220 °C, 5 min, and a hydrogen pressure of 1 MPa resulted in the highest yield of HMF, and selectivity of 26.9% was achieved when the Al-SBA-15 catalyst was used. Moreover, under the same conditions, cellulose extracted from eucalyptus, a practical biomass, was converted to HMF in a one-pot synthesis with a yield of 13.0 C-mol.%.Display Omitted
Keywords: Solid acid catalyst; Eucalyptus; Cellulose; HMF production; Al-SBA-15 catalyst; Sulfated zirconia oxide;
Biomass as an energy source in coal co-firing and its feasibility enhancement via pre-treatment techniques by Buddhike Neminda Madanayake; Suyin Gan; Carol Eastwick; Hoon Kiat Ng (287-305).
Biomass co-firing is recognised as a crucial technology to aid in curbing the use of fossil fuels, particularly due to its relative ease of implementation. This article provides an introduction to biomass and its use as a fuel – as with any fuel, this includes its characterisation and energy conversion. Key fuel properties, both chemical and thermochemical, are described. Combustion is the energy conversion technique that is focused on; the implications of biomass co-firing are discussed along with an overview of current co-firing technology. Biomass pre-treatment techniques are identified as a means of alleviating some of the drawbacks of co-firing, and this is the chief focus of this paper. A comprehensive review is carried out on torrefaction and leaching, which aim to enhance the physical/thermochemical and chemical properties of the biomass, respectively. Milling and pelletising are also looked at. Additionally, the practical aspects of implementing biomass pre-treatment are explored, and areas where further research work is needed are identified. The final section of the review is concerned with CO2 avoidance, which is one of the key drivers behind adopting biomass co-firing.
Keywords: Biomass; Pre-treatment; Co-firing; Torrefaction; Leaching;
Cu-BTC metal-organic framework natural fabric composites for fuel purification by Reda M. Abdelhameed; Hossam E. Emam; João Rocha; Artur M.S. Silva (306-312).
Viscose and wool fabrics were modified by the insertion of the metal organic framework copper(II) benzene-1,3,5-tricarboxylate (Cu-BTC MOF) through two different techniques, ex situ (ex-Cu-BTC@fabric) and in situ (Cu-BTC@fabric), and the obtained new materials used to remove phenol from petroleum fractions. The copper and MOF contents were, respectively, 32.3–34.5 mg g− 1 and 102.1–110.0 mg g− 1 for in situ, and 15.6–17.3 mg g− 1 and 50.0–55.2 mg g− 1, for ex situ modified fabrics. The efficiency of phenol removal from n-octane was followed the order of fabric < ex-Cu-BTC@fabric < Cu-BTC@fabric and viscose fabric exhibited much higher affinity. The highest phenol removal percentage (90%) was attained after 12 h contact time. The maximum adsorption capacity was 333 mg g− 1 for Cu-BTC@viscose and 306 mg g− 1 after 6 successive recovering cycles. The adsorption was pseudo-second order and well fitted to the Langmuir isotherm. The adsorption mechanism may occur via the (i) physical deposition into the Cu-BTC pores, (ii) hydrogen bonding between the phenol hydroxy groups and those of cellulose, and (iii) Cu(II) phenol chelation. The results showed that the insertion of Cu-BTC MOF into natural fabrics is a promising way to effectively remove phenols from fuel.Display Omitted
Keywords: Natural fabrics; MOF; Phenol; Fuel purification; Adsorption; Reusability;
Predicting the degree of surface oxidation on fine coals by measuring the oxygen transfer rate in coal suspensions by Xumeng Chen; Ziyong Chang; Yongjun Peng (313-319).
Coal surface oxidation plays a dominant role in differential coal flotation and the utilization of coal products. However, a robust and reliable tool to determine coal surface oxidation in coal preparation plants is not currently available. In this study, a novel technique was developed to determine the degree of coal surface oxidation by measuring the adsorption rate of oxygen on coal surfaces after understanding the nature of oxygen transfer in water and oxygen adsorption on oxidized and un-oxidized coal surfaces. In this study, coal samples with different extents of surface oxidation were prepared and the degree of coal surface oxidation was quantified by X-ray photoelectron spectroscopy (XPS) as the percentage of oxidized carbon. Oxygen was purged into the coal suspension at a constant flow rate and the change of dissolved oxygen (DO) concentration was monitored. It was found that the DO concentration increased with oxygen purging time and the rate of increase was dependent on the degree of coal surface oxidation. A faster increase in DO concentration was observed for more oxidized coals, which is related to a slower adsorption of oxygen on oxidized coal surfaces and, therefore, more dissolved oxygen remained in the suspension. The kinetics of the change of DO concentration was calculated using the oxygen transfer equation, based on which the rate of oxygen adsorption on coal surfaces was obtained. A linear relationship was found between the oxygen adsorption rate and the degree of coal surface oxidation. This technique may be implemented in coal preparation plants as a daily tool to closely monitor the coal oxidation status due to its simplicity and accuracy.Display Omitted
Keywords: Coal; Surface oxidation; Oxygen transfer; Oxygen adsorption; Dissolved oxygen;
Hydrocracking of vacuum residue with solid and dispersed phase catalyst: Modeling of sediment formation and hydrodesulfurization by Eduard Manek; Juma Haydary (320-327).
Effect of dispersed Mo based catalyst on residual hydrocracking was investigated in this paper. The study was performed in an industrial scale hydrocracking unit with the average reactor temperature of 399–419 °C and pressure of 18 MPa. Vacuum residue from Ural crude oil was fed to the reactor. A sediment formation model was proposed with parameters sets for the regime with classical supported Ni-Mo/Al2O3 catalyst and for that with a combined system of supported and dispersed catalyst. Four process parameters were incorporated in the model equation: reaction temperature, hydrogen partial pressure, exothermic gain and hydrogen makeup to feed mass ratio. A decrease of the sediment formation with the application of dispersed Mo catalyst was observed, which results in higher Mo concentration in the liquid phase and thus in higher hydrogenation activity and stabilization of coke precursors. Hydrodesulfurization was also investigated and a sulfur distribution model was created with parameters for both regimes. The model contains three lumps with significant sulfur content: sulfur contained in the vacuum residue, sulfur contained in the vacuum gas oil and hydrogen sulfide. Application of the catalyst and increase of reaction temperature from 399–414 °C to 414–419 °C resulted in increase of average sulfur conversion in vacuum residue from 86.5% to 87.9%.
Keywords: Residual hydrocracking; Sediment formation; Hydrodesulfurization; Mathematical modeling;
Co-hydrotreatment of tire pyrolysis oil and vegetable oil for the production of transportation fuels by Yinglei Han; Filip Stankovikj; Manuel Garcia-Perez (328-339).
Catalytic hydrotreatment followed by products isomerization is an effective technology to convert vegetable oil to a green fuel composed of straight and branched chain aliphatic hydrocarbons. The content of aromatics in this fuel is very low. In this paper we study the co-hydrotreatment of vegetable oil and tires oil in the presence of a CoMo/Al2O3 catalyst as a way of utilizing existing infrastructure created for vegetable oil processing for tire oil up-grading in order to obtain fuel cuts with aromatics. Hydrotreatment studies with different vegetable oil/tires oil blend ratios were conducted. The yield and composition of the resulting hydrotreated oils are reported. Aliphatic hydrocarbons ranging from C7 to C20 derived from vegetable oils and aromatics from C6 to C16 derived from the tire oil were identified as products. The resulting oils were then successfully distilled into naphtha, kerosene, diesel and gas oil cuts. The yield, chemical composition and the fuel properties of the transportation fuel cuts obtained are reported and compared with commercial petro derived fuels.Display Omitted
Keywords: Co-hydrotreatment; Tire pyrolysis oil; Vegetable oil; Catalyst characterization; Catalytic behavior; Distillation; Fuel characterization;
Mercury emission from sintering process in the iron and steel industry of China by Wenqing Xu; Mingpan Shao; Yang Yang; Ruihui Liu; Yinghong Wu; Tingyu Zhu (340-344).
Iron and steel production is one of the most significant anthropogenic sources of atmospheric mercury emission. However, there is little information about this source in China. In this study, we focused on three typical Chinese sintering furnace processes. Mercury in flue gas was sampled using the EPA Method 30B and Ontario Hydro Method, and solid samples were also analyzed. We found that 1.12–4.66% of mercury input in sintering furnace processes was emitted into the atmosphere. The total mercury concentrations in the sintering furnace flue gas were 17.773, 31.765 and 18.275 μg/m3; the major mercury species was oxidized form, which accounted for 73.4– 94.7% of the total mercury. The mercury concentrations in the stack flue gas were 0.373, 0.533 and 0.465 μg/m3, while its removal efficiencies by air pollution control devices (APCDs) were 97.5%, 81.1% and 96.8%, and its emission factors were 2.49, 2.71 and 1.28 mg/t sinter. The main mercury inputs were iron ore, coal, coke and lime, where the iron ore input was 74.84– 92.22% of the total mercury quantity. Moreover, mercury was distributed in fly ash (19.22– 81.54%), gypsum (13.29– 46.00%), iron ore sinter (0– 11.45%), and flue gas (1.12– 4.66%). An approximate mercury mass balance could be obtained from various samples in this study.Display Omitted
Keywords: Hg; Emission; Speciation; Removal efficiency; Distribution;
Superactivated carbons by CO2 activation of loquat stones by M. Plaza-Recobert; G. Trautwein; M. Pérez-Cadenas; J. Alcañiz-Monge (345-352).
This work presents CO2 activation approach towards controlled preparation of superactivated carbons (SAC) from a new lignocellulosic residue: loquat stones. This study demonstrates the potential use of loquat stones as a precursor in the preparation of SAC, reaching maximum BET surface area 3500 m2/g and total micropore volume 1.84 cm3/g. Studies on CO2 activation at different temperatures reveal two interesting results: 1) Loquat stones can be activated at high temperatures, up to 1100 °C, achieving similar volumes of porosity with short maintenance times (30 min). 2) The greater facility for eliminating mineral matter content of the loquat stones, as well as the scarce presence of K in its composition.The high volumes both of total and narrow microporosity that are obtained in the activation of carbonized loquat stones can be explained both by the traces of mineral matter that they contain and the carbonaceous microstructure of its carbonized state.Display Omitted
Keywords: Superactivated carbon; Carbon dioxide activation; Microporosity; Chemically and diffusion controlled gasification;
Flow stabilized porous heterogeneous combustor. Part I: Design and development by Anthony Carmine Terracciano; Samuel De Oliveira; Manuel Robayo; Subith S. Vasu; Nina Orlovskaya (353-362).
A heterogeneous combustor was developed where the flame position within the ceramic porous media, contained within the combustor, could be controlled using the reactant flow rate. The porous media within the combustor can be coated with a catalyst to further promote combustion; this apparatus was designed to enable the investigation of various catalysts to be evaluated for their effectiveness as promoters of combustion. A unique feature of the combustion chamber showcased within this work is that the position of the flame is controlled by flow rates rather than the conventional method of flame arrestors, minimizing pressure drop across the combustion chamber. The developed operational system consists of six well-integrated and interconnected parts: the combustion chamber, a reactant storage and metering system, the reactant delivery nozzle, the exhaust sampling port, an externally located microphone, and a CCD camera. Within this present work Al2O3 porous media of 10 ppin was used during the initial testing of the developed system.
Keywords: Heterogeneous combustion; Porous media; Instrumentation; Combustor design; Alumina (α-Al2O3); Combined heat and power (CHP);
Auto-ignition of a carbon-free aqueous ammonia/ammonium nitrate monofuel: A thermal and barometric analysis by Bar Mosevitzky; Gennady E. Shter; Gideon S. Grader (363-368).
A carbon-free aqueous solution of ammonium hydroxide and ammonium nitrate (AAN) was studied using differential thermal and barometric analyses under initial N2 pressure of up to 4.6 MPa. The suggested nitrogen-based monofuel exhibited three distinct exothermic processes during heating. Their onset temperatures increased as the initial nitrogen pressure was raised. In addition, a higher extent of reaction was observed at high nitrogen pressures. This result was attributed to the effect of mass diffusion in the system, which decreased at higher pressures. Using a modified mechanism for the combustion of nitrogen-based fuels, the thermal ignition process was simulated. The resulting auto-ignition temperature values were shown to be in good agreement with experiments at initial nitrogen pressures of up to 2.3 MPa. Above this pressure, the agreement between experimental and model results was hampered by mass diffusion effects. Using the modified mechanism, the main chemical pathways prior to auto-ignition of AAN were identified and the reactions leading to ignition were discussed. This paper presents for the first time the auto-ignition of AAN and explores the combustion chemistry of this carbon-free monofuel.
Keywords: Monofuel; Nitrogen-based alternative fuel; Differential barometric analysis; Differential thermal analysis; Reaction mechanisms;
Influence of binder (coal tar and pitch) addition on coal caking property and coke strength by Seiji Nomura; Takashi Arima (369-375).
In order to increase the usage of semi-soft coking coal, various technologies have been developed and commercialized. Among these, an additive for improving coal caking property (hereinafter referred to as a binder) is promising. Here the mechanism of binders for improving coal caking property and the influence of binder addition to coal with different particle size on caking property and coke strength were investigated. The thermogravimetric analysis and dilatometry tests have suggested that as for coal-derived binder, the gas generating from the binder interacts with coal before coal starts to soften and that coal is reformed in-situ during heating by the interaction, which leads to enhancement of caking property. On the other hand, as for petroleum-derived binder, the experiments have implied that the reason why the petroleum-derived binder enhances coal caking properties is that the gas generating as a result of pyrolysis of the petroleum-derived binder “in” the plastic coal helps the plastic coal to swell and become more fluid. Moreover, dilatation differs greatly with coal types and particle size fractions. When the specific dilatation volume of fine coal is equal to that of coarse coal, the coke structure becomes more homogeneous, which leads to high strength coke structure. There is a possibility that under the binder addition ratio being constant, coke with maximum DI can be obtained by adding binders to fine coal and coarse coal separately so that the specific dilatation volume of fine coal becomes equal to that of coarse coal.
Keywords: Semi-soft coking coal; Additive; Pitch; Binder; Caking property; Dilatation; Coke strength;
Impact of nitrogenous alkaline agent on continuous HTL of lignocellulosic biomass and biocrude upgrading by Claus Uhrenholt Jensen; Lasse A. Rosendahl; Göran Olofsson (376-385).
Continuous hydrothermal liquefaction (CHTL) of lignocellulosic biomass with subsequent hydrotreating is carried out to study the effect of NH3 versus NaOH as alkaline HTL catalyst. Product analysis include Py-GCxGC–MS, simulated distillation and fractional distillation. Ammonia enhances biocrude quality slightly in terms of H/C ratio, density and HHV, but a significant coke formation of 11 wt.% is observed. Furthermore, ammonia pollutes the biocrude with 2.7 wt.% nitrogen, which is observed to inhibit hydrotreating conversion. In comparison, CHTL with NaOH is associated with a 43 wt.% yield of a hydrotreatable biocrude, stable TOC levels during aqueous phase recirculation and mass, carbon and energy balance closure. Hydrotreating eliminates the TAN, reduces oxygen to 2–3 wt.% and produces a promising fuel bio-blendstock with ultra-low sulphur and a diesel fraction equal to 43%.
Keywords: Biofuel; Hydrotreating; GCxGC–MS; Distillation; Hydrofaction;
Separation and structural characterization of groups from a high-volatile bituminous coal based on multiple techniques by Bin Tian; Yingyun Qiao; Lei Bai; Fangjing Liu; Yuanyu Tian; Kechang Xie (386-395).
Although considerable progress has been made in revealing the coal macromolecular structure via solvent extraction, there remains a challenge in elucidating the coal structure due to low extraction yields of coal, poor selectivity of extraction solvents, and complexity of extracts. In this work, a high-volatile bituminous coal was successfully separated into seven groups (G1–G7) with less diversity within each class using multistep extraction followed by column chromatography. The total extraction yield (dmmf) reached up to 56% and the structural characteristics of the seven groups were identified and investigated with a series of analytical techniques. The results showed that the individual groups had a rather unique composition and their chemical properties were different in elemental composition, functional groups, aromatic cluster size, number and length of the alkyl side chains, and degree of order, which resulted in differences of their pyrolysis reactivities. Aliphatic hydrogen accounted for 99% of total hydrogen in n-heptane eluted fraction (G4) but the aliphatic degree in the extract residue (G1) was only 35.7%. The ratios of aromatic bridgehead carbon were 0.32, 0.30, and 0.27 for G1, CCl4 insoluble fraction (G2), and n-heptane insoluble fraction (G3), respectively. Additionally, total volatiles achieved 99.8, 98.1, 98.2, 89.0, and 60.0%, respectively during pyrolysis of G4, toluene eluted fraction (G5), ethyl acetate eluted fraction (G5), methanol eluted fraction (G7), and G3 at end temperature of 800 °C, which were substantially higher than those for G1 and G2. In comparison with the partition of coal structure using maceral components, the proposed separation method provides an efficient and convenient investigating for structural exploration and these data can be combined to create structures that are cognitive of the structural diversity present. Through this, exploration of the complex conversion mechanism of coals would become more accessible during pyrolysis, gasification, liquefaction, and coking processes.Display Omitted
Keywords: Coal; Solvent extraction; Group separation; Column chromatography; Structure features;
A recyclable and highly active magnetic solid superbase for hydrocracking C―O bridged bonds in sawdust by Xiang-Xue Liu; Zhi-Min Zong; Wei-Tu Li; Xiang Li; Zhan-Ku Li; Sheng-Kang Wang; Xian-Yong Wei (396-403).
A novel and highly active magnetic solid superbase (MSSB) with extraordinary recovery and recycling properties was prepared by impregnating Mg2Si onto mesoporous silica coated magnetite via one-pot preparation and successfully applied in the catalytic hydroconversion (CHC) of sawdust at 220 °C. Detailed molecular compositions of the soluble portions from non-catalytic hydroconversion (SPNCHC) and CHC (SPCHC) were characterized with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer (GC/MS). As a result, the yield of SPCHC is significantly higher than that of SPNCHC and most of the GC/MS-detectable compounds in SPCHC are guaiacols, while SPNCHC is rich in guaiacols and esters, indicating that MSSB effectively catalyzed the cleavage of C―O bridged bonds in sawdust. The mechanism for catalytically hydrocracking C―O bridged bonds over MSSB is proposed using benzyloxybenzene and oxybis(methylene)dibenzene as model compounds. MSSB can be easily separated by using an external magnetic field and the recovered MSSB proved to be still highly active for catalyzing the hydrocracking of C―O bridged bonds in sawdust.
Keywords: Magnetic solid superbase; Sawdust; C―O bridged bonds; Hydrocracking;
Coke and radicals formation on a sulfided NiMo/γ-Al2O3 catalyst during hydroprocessing of an atmospheric residue in hydrogen donor media by Yuxin Yan; Lei Shi; Qingya Liu; Xinge Shi; Ting Wang; Qiaoqiao Zhou; Zhenyu Liu; Wei Han; Mingfeng Li (404-411).
Coking on catalyst during hydroprocessing of petroleum residues is an important issue that should be addressed for better catalyst performance. This paper studies reaction and coking behaviors of Maoming atmospheric residue (AR) over a sulfided commercial NiMo/γ-Al2O3 catalyst in the presence and absence of a hydrogen donor solvent, tetrahydronaphthalene (THN), in a micro-reactor at temperatures of 400–460 °C and reaction time of 0–60 min. It reports the changes in yields of CS2 soluble matter (CS2-S), CS2 insoluble matter (coke) and gas, as well as the changes in quantity of coke on the catalyst and in radical concentration of the reaction system, coke on catalyst and CS2-S. It is found that compared with the changes in yields, which are significant at temperatures higher than 420 °C, the changes in radical concentration are significant at 400 °C. The catalyst promotes hydrogen donation of THN, which lowers the amounts of coke formed in the liquid phase, on the catalyst, and the activation energy of coking on the catalyst.
Keywords: Atmospheric residue; NiMo catalyst; Hydrogen donor solvent; Radical concentration; Coke; Kinetics;
Flow stabilized porous heterogeneous combustor. Part II: Operational parameters and the acoustic emission by Anthony Carmine Terracciano; Samuel De Oliveira; Subith S. Vasu; Nina Orlovskaya (412-420).
Heterogeneous combustion is an advanced combustion technique, which incorporates a highly porous ceramic media into the combustion chamber, and enables the flame to propagate within the pores of the ceramic media. Heat exchange between the solid and gas phases within the combustion chamber can enable a flame to exist that is highly resilient to momentary disruptions in reactant flow rates while also enabling localized temperatures to be in excess of the adiabatic flame temperature, a phenomena known as superadiabatic combustion. While beneficial to performance, the incorporation of the solid into the combustion chamber greatly complicates observations and understanding of the combustion phenomena occurring within the voids and on the surface of the solid media, therefore, development of non-invasive and low cost instrumentation is always a priority to get a better understanding of the phenomena occurring within the combustion chamber. Within this work, a novel instrumentation technique, acoustic emission profiles obtained by collecting the noise during heterogeneous combustion, is used to measure characteristics of the flame, in addition to the optical characterization by CCD camera and the thermal characterization by thermocouples to characterize the performance of newly developed heterogeneous porous combustor.
Keywords: Heterogeneous combustion; Acoustic spectroscopy; Combined heat and power (CHP); Alumina (α-Al2O3); Porous media; Lean methane combustion;
Study on effect of dimethyl ether addition on combustion characteristics of turbulent methane/air jet diffusion flame by Yinhu Kang; Wei Shuang; Xingchi Jiang; Yangfan Song; Sicong Sun; Pengyuan Zhang; Yuming Sun; Xiaofeng Lu; Quanhai Wang; Xiaolong Gou; Xuanyu Ji (421-435).
The kinetics and soot and NOx emission characteristics of the CH4/dimethyl ether (DME) jet diffusion flames (JDFs) are studied by experiments and simulations with a detailed chemical mechanism. The results showed that decomposition of DME in the pyrolysis zone generated massive CH3, which changed the local flame structure and soot-correlated chemistry to some extent. Due to reductions of the incipient species concentrations including benzene (A1), pyrene (A4), C3H3, and C2H2, soot loading of the CH4 JDF decreased by reducing margins with DME addition. A1 and thus soot formation rates due to DME addition were most sensitive to the recombination reaction of C3H3 (C3H3 + C3H3 = A1). With respect to the CH4/DME JDFs, NOx was emitted mainly through the thermal and prompt pathways. The thermally-generated EI NOx increased exponentially with DME addition because of the increasing enhancement of OH concentration in the radical pool. By contrast, the promptly-generated EI NOx decreased in reducing margins with DME addition because of the reducing decrease in CH concentration. The synergistic effect of DME addition on the total NOx emission, i.e. the overall EI NOx decreased firstly and then increased with DME addition, was examined in this paper. Additionally, it is reported that the 40%CH4/60%DME case was comprehensively optimal in terms of soot and NOx emission reductions.Display Omitted
Keywords: Dimethyl ether; Methane; Soot; NOx; Emission mechanism;
Enhancement of conversion from bio-syngas to higher alcohols fuels over K-promoted Cu-Fe bimodal pore catalysts by Mingyue Ding; Longlong Ma; Qian Zhang; Chenguang Wang; Wennan Zhang; Tiejun Wang (436-441).
A novel K-promoted Cu-Fe bimodal derived catalyst was designed to optimize the catalytic activity and higher alcohols selectivity in higher alcohols synthesis (HAS). The characterization results indicated that the Cu-Fe bimodal derived catalyst presented the bimodal pore structures. The adding of K promoter increased the BET surface area and promoted the dispersion of Cu and Fe species in the bimodal pores without destroying the bimodal structure, whereas the excessive adding of potassium resulted in easily the aggregation of bimetal active species. Incorporation of moderate K content enhanced the reduction of Cu and Fe species and promoted the formation of active bimetal species for HAS, while the bimodal derived catalyst with excessive K content restrained the reduction of bimetal particles, decreasing the catalytic activity for higher alcohols synthesis. In addition, the gradual increasing of K content in the Cu-Fe bimodal derived catalyst strengthened the interaction of K and bimetal active species, which was combined with the “confinement effect” of bimodal pore structures, shifting product distribution towards C2 + OH.
Keywords: Higher alcohols synthesis; Bimodal pore support; Cu-Fe based catalyst; K promoter;
Exploration on the removal mechanism of sulfur ether model compounds for coal by microwave irradiation with peroxyacetic acid by Longfei Tang; Shiwei Wang; Jifeng Guo; Xiuxiang Tao; Huan He; Li Feng; Songjiang Chen; Ning Xu (442-447).
The removal mechanism of sulfoether in coal by microwave with peroxyacetic acid, was determined by evaluating changes in sulfur containing compounds after desulfurization by XANES and GC/MS. The highest occupied molecular orbital composition, the electrostatic potential distribution, and the sulfur containing bond dissociation energy (BDE) of model compounds molecules were also determined to support the experimental results. Results showed that sulfoether was easily oxidized to corresponding sulfoxide or sulfone in treated samples. Although benzyl sulfides were more readily oxidized than disulfides, the latter was easier to remove due to the higher breaking probability of the S―S bond. The sulfur atoms within sulfur ether in coal are the active sites for electrophilic reaction. As sulfur atoms were oxidized, the sulfur containing BDEs decreased considerably and the dipole moments of sulfoether molecules increased. These findings suggest that the removal efficiency of sulfoether in coal may be improved by moderate and selective oxidation under microwave treatment.
Keywords: Desulfurization; Microwave; Sulfur ether; Sulfur-containing model compounds;
Optimal design of a large scale Fischer-Tropsch microchannel reactor module using a cell-coupling method by Ikhwan Jung; Jonggeol Na; Seongho Park; Jeongwoo Jeon; Yong-Gi Mo; Jong-Yeol Yi; Jong-Tae Chung; Chonghun Han (448-459).
In this study, a C5 + 0.5 BPD microchannel Fishcer-Tropsch process with a U-type cooling system was modeled using a cell coupling method, and multi-objective optimization was conducted using an artificial neural network as a surrogate model. Two objective functions (reactor core volume and maximum process temperature rise, ΔTmax) were to be minimized using seven design variables as optimization variables. Reactor core volume represents a reactor's compactness, which is essential for a micro-channel reactor, whereas ΔTmax is highly related to reactor stability. A Pareto optimal solution was obtained for a feasible ΔTmax range of 3.8–6.8 K. The optimal reactor core volume for ΔTmax of 3.8 K was 1.45 times larger than that for ΔTmax of 6.8 K. As ΔTmax increases, the total reactor length is shortened while the total width and height remain relatively constant. A sensitivity analysis of Pareto optimization was conducted for two types of parameters: 1) coolant flow rate, and 2) fixed design parameters. Coolant flowrates over 750 LPM were found to be inefficient for the given conditions. Fixed design parameters were closely related to the capabilities of the reactor fabricator. The present study suggested a priority order for modifying fixed design parameters to increase compactness. Suitable points can be selected based on the specific requirements of plant conditions.
Keywords: Fischer-Tropsch reaction; Compact microchannel reactor; Cell-coupling method; Multi-objective optimization; Artificial neural network; Orthogonal analysis;
Selection of dolomite bed material for pressurized biomass gasification in BFB by Chunguang Zhou; Christer Rosén; Klas Engvall (460-473).
Dolomite is considered advantageous as bed material in fluidized bed gasification processes, due to its catalytic tar cracking and anti-sintering properties. However, in case of pressurized fluidized bed gasifiers, the use of dolomite is challenging. High temperature in the presence of steam favors the production of clean syngas due to the intensified cracking of tar in the presence of CaO, whereas it simultaneously increases the tendency of fragmentation of dolomite particles after full calcination. The present study was carried out to examine the influence of the properties of dolomite on the stability of dolomite in a pressurized fluidized bed gasifier, with the aim of determining criteria for dolomite selection. Glanshammar dolomite exhibited a better stability in the mechanical strength after calcination, compared to Sala dolomite. The corresponding change of micro-structure that occurred during dolomite chemical transformation was presented. The crystal pattern and Si distribution in the crystal lattice are the possible explanations for the superior performance of the Glanshammar dolomite compared to the Sala dolomite.
Keywords: Dolomite; Pores; Crystal; Pressurized fluidized bed; Gasification;