Fuel Processing Technology (v.160, #C)
Editorial Board (IFC).
Experimental study of glycerol etherification with C5 olefins to produce biodiesel additives by José Felipe Izquierdo; Ester Iniesta; Pablo R. Outón; María Izquierdo (1-7).
The etherification of glycerol with isoamylenes has been studied employing twelve catalytic ion-exchange resins in order to establish the basis for a novel green process coming from this renewable source. Two compositionally different experimental approaches to transform glycerol in biodiesel additives were considered i.e. using glycerol (G), tert-amyl alcohol (TAA) and/or isoamylenes (IA) in variable molar ratios. Reactions were carried out in a stainless steel batch minireactor at temperatures between 313 and 348 K, autogenous pressure to 1.5 MPa and 1–24 h reaction time. The influence of initial molar ratio of reactants, temperature, pressure, reaction time and the catalyst employed were evaluated to optimise the process and attain the maximum conversion of glycerol. Optimization of mixtures of glycerol with TAA resulted in maximum glycerol conversion attaining 51% whilst greater glycerol conversions close to 70% were achieved using mixtures of glycerol/isoamylenes/tert-amyl alcohol.
Keywords: Biodiesel additives; Glycerol; Isoamylenes; Etherification; Biofuels;
Degradation behaviors of SOFC due to chemical interaction between Ni-YSZ anode and trace gaseous impurities in coal syngas by Koji Kuramoto; Sou Hosokai; Koichi Matsuoka; Tomohiro Ishiyama; Haruo Kishimoto; Katsuhiko Yamaji (8-18).
The influence of the selected trace species of S, Cl, and Si contained in post-CCS (Carbon Capture and Storage) hydrogen-enriched coal syngas in the EAGLE integrated gasification combined cycle with carbon capture and storage (IGCC/CCS) pilot plant on the performance of solid oxide fuel cell (SOFC) with cermet anode of NiO and yttria-stabilized zirconia (YSZ) was examined. We conducted power generation tests using an electrolyte-support single button-shaped cell fueled by simulated post-CCS syngas with H2S, HCl, and tetraethylorthosilicate (TEOS) to determine whether the performance of the SOFC anode was affected by the trace impurities. We confirmed that injections of trace levels of H2S ranging from 1 to 10 ppm always resulted in a modest but abrupt performance drop soon after injection, the magnitude of which depended on H2S concentration as well as current densities. Long-term exposure tests fueled by simulated syngas with H2S or HCl did not reveal any appreciable acceleration in performance degradation in the presence of impurities, although there was a small amount of sintering of component particles in the diffusion layer. Injection of TEOS, a chemical substance representing Si vapor source, resulted in performance degradation with an increase in ohmic and polarization resistances. Deposition of Si species occurred on the surface and in the boundary region of the active and diffusion layers of the anode. Plausible diffusion and deposition mechanisms of trace gaseous Si species around the layered Ni-YSZ anode, possibly caused by thermal polymerization of TEOS and generation of SiO due to hydrogen-induced SiO2 reduction, are presented.
Keywords: SOFC; Coal syngas; H2S; HCl; TEOS; Chemical degradation; Ni-YSZ anode;
In situ upgrading of Shengli lignite pyrolysis vapors over metal-loaded HZSM-5 catalyst by Tian-Long Liu; Jing-Pei Cao; Xiao-Yan Zhao; Jing-Xian Wang; Xue-Yu Ren; Xing Fan; Yun-Peng Zhao; Xian-Yong Wei (19-26).
This work is aimed to study in situ upgrading of Shengli lignite pyrolysis vapors over different metal-loaded HZSM-5 in a drop tube reactor. Co/HZSM-5, Mo/HZSM-5 and Ni/HZSM-5 (5.0 wt%) were prepared by wet impregnation and characterized by N2 adsorption-desorption analyzer, X-ray diffraction, transmission electron microscope, Fourier transform infrared spectrometer and temperature programmed desorption of ammonia. The effects of temperature and catalyst on product yields and tar properties were investigated. The results show that the optimal temperature for liquid product was 600 °C and aromatics can be directly produced from solid lignite by catalytic fast pyrolysis over metal-loaded HZSM-5 under such mild condition. Due to the participation of metal and acid sites, the bifunctional metal-loaded HZSM-5 showed comparable catalytic activity for deoxygenation reaction in the valorization of oxygen content below 7.1%. The introduction of metal causes the increase of aromatics and the decrease of organic oxygen species in upgraded tar remarkably. Among the catalysts, Ni/HZSM-5 exhibited the best performance for production of high quality tars with highest aromatics content of 94.2% (area%), which can be used as a potential candidate for catalytic upgrading of pyrolysis oil.
Keywords: HZSM-5; Metal; Catalyst; Pyrolysis; Aromatics;
Removal of the neutral oil entrained in deep eutectic solvents using an anti-extraction method by Youan Ji; Yucui Hou; Shuhang Ren; Congfei Yao; Weize Wu (27-33).
Forming deep eutectic solvents (DESs) by quaternary ammonium salts (QASs) and phenolic compounds to extract phenolic compounds from oil mixtures is effective. However, a small amount of neutral oil is entrained in the DESs. In this work, we proposed an anti-extraction method to remove the neutral oil entrained in DESs. Low-carbon alkanes (LCAs, including n-hexane, cyclohexane, and n-nonane) were added to model DESs to remove neutral oil. We found that the LCAs could effectively remove neutral oil entrained in the DESs. Of the three LCAs, n-hexane showed the best performance, and the removal rate of neutral oil could reach as high as 92.2%. The separation process could complete within 15 min, and the removal rate of neutral oil did not change significantly with temperature. In addition, n-hexane could effectively remove neutral oils in DESs formed by real coal tar and choline chloride. The neutral oil content in the phenolic compound product decreased to only 1.9 wt%, which greatly improves the purity of the phenolic compound product.Display Omitted
Keywords: Removal; Neutral oil; Deep eutectic solvent; Anti-extraction method; Phenolic compounds;
Catalytic cracking of 4-(1-naphthylmethyl)bibenzyl in sub- and supercritical water by Li Tan; Oyunkhand Erdenebaatar; Guoguo Liu; Noriyuki Yamane; Peipei Ai; Akihisa Otani; Yoshiharu Yoneyama; Guohui Yang; Noritatsu Tsubaki (34-38).
The upgrading and reforming of coal-derived liquids are necessary for the application of high value-added liquid fuels, but the processing is difficult due to the amounts of impurities. In this paper, the catalytic cracking of 4-(1-naphthylmethyl)bibenzyl (NMBB) as a model reaction was studied deeply under sub- and supercritical water environment. Water might serve as a cheap and environmental H donor, which was more efficient than the supplied H2 in the processing of coal-derived liquids upgrading. Meanwhile, sub- and supercritical water could provide a homogeneous reaction environment for NMBB cracking as special solvents. The NMBB conversion under subcritical water was much higher than that under supercritical water. Furthermore, for H2 atmosphere, NMBB conversion was higher than that of N2 atmosphere, indicating that the process of in-situ H2 formation from subcritical water was more easily. Therefore, the cracking of NMBB under subcritical water and H2 atmosphere could be regarded as a reasonable reaction condition.Display Omitted
Keywords: NMBB; Cracking; Supercritical water; Subcritical water; Ni/AC;
Effect of the presence of NaCl vapour on indirect sulphation of limestone by Rui Han; Fei Sun; Jihui Gao; Siyu Wei; Yanlin Su (39-46).
The effects of the presence of NaCl vapour on limestone SO2 capture behaviour were examined. When NaCl was present in the sulphation atmosphere, the effects of the presence of H2O, reaction temperatures, particle sizes and NaCl concentrations on limestone SO2 capturing were studied in a tailor-made three-section control horizontal furnace. The presence of NaCl in the sulphation atmosphere clearly improves the limestone SO2 capturing capacities. H2O has a strong impact on the effect of NaCl vapour on limestone sulphation. In the absence of H2O, the enhanced effect of NaCl vapour on limestone sulphation is reinforced further. The presence of NaCl vapour changes the effects of reaction temperatures on limestone SO2 capturing capacities. The optimum sulphation temperature for limestone in the presence of 1058 ppm NaCl is 1000 °C rather than the optimum temperature of 850 °C in the absence of NaCl. A higher limestone SO2 capturing capacity is achieved with a smaller particle size in the presence of NaCl. The presence of NaCl vapour reduces differences in limestone SO2 capturing capacities with different particle sizes. At 850 and 1000 °C, the SO2 capturing capacity of limestone increases and later decreases with the Na/S mole ratio increasing. While, the SO2 capturing capacity of limestone increases monotonically with the Na/S mole ratio increasing at 1200 °C. The Na+ of NaCl vapour doped into the product layer during sulphation, which enhances the SO2 capturing capacity of limestone. The reaction between NaCl vapour and SO2 reduces SO2 concentrations, negatively affecting limestone sulphation, while the generated HCl promotes limestone SO2 capturing through changes in the surface morphology of the product layer. The effect of NaCl vapour on limestone sulphation is thus dependent on the extent of reactions between NaCl vapour and SO2.
Keywords: Fluidized-bed; High sodium coal; NaCl vapour; Limestone; Sulphation reaction;
Chemical Looping Combustion of liquid fossil fuels in a 1 kWth unit using a Fe-based oxygen carrier by A. Serrano; F. García-Labiano; L.F. de Diego; P. Gayán; A. Abad; J. Adánez (47-54).
The integrated use of low-value hydrocarbons from the refining of crude oil under Chemical Looping Combustion (CLC) conditions can satisfy the demands of heat and steam of the refining process itself while at the same time reducing CO2 emissions up to 50% in oil refineries. This work evaluated the use of three different fossil liquid fuels, i.e., diesel, mineral lubricant oil and synthetic lubricant oil in a 1 kWth CLC unit working with a Fe-based oxygen carrier prepared by impregnation method. The effect of key parameters of the CLC process was studied with the same batch of oxygen carrier particles for a total of 150 operation hours. With regard to the results obtained, every fuel tested was able to achieve 90% combustion efficiency being synthetic lubricant oil the most reactive fuel studied. Hydrocarbon reactivity seems to depend on the nature of the chemical bonds, being higher for alkenes (synthetic lubricant oil) than for alkanes (diesel and mineral lubricant oil). CH4 was revealed as a relatively stable intermediate combustion product for these liquid fuels. Therefore, oxygen carrier's reactivity towards this gas becomes crucial for the overall conversion. The characterization carried out to the oxygen carrier after operation revealed no evidence of changes derived from the sulphur or impurities present in the fuel. Therefore, the Fe-based material herein used seems to be suitable for conversion of fossil liquid fuels.
Keywords: CO2 capture; Liquid fossil fuels; Chemical Looping Combustion; Oxygen carrier;
Comparison of characteristics of twenty-one types of biochar and their ability to remove multi-heavy metals and methylene blue in solution by Yan Wang; Ronghou Liu (55-63).
The characteristics of twenty-one types of biochars as well as their capacities to remove multi-heavy metals (Cu2 +, Pb2 +, Cd2 +, and Zn2 +) and methylene blue were compared in order to screen biochars applied for pollutants removal. The adsorption mechanisms of heavy metals and methylene blue by biochars were analyzed. Results showed that the oxygen and hydrogen contents, molar O/C and H/C ratios of biochars decreased while the carbon and ash contents, the pH value increased with pyrolysis temperature increased from 350 °C to 550 °C. The removal efficiency of Pb2 + (1.90–30.42%) was higher than Cu2 + (0.34–12.83%) and other metals in 100 mg L− 1 multi-heavy metals solutions. Cotton straw biochar from slow pyrolysis showed the highest removal capacity for Pb2 + and Cu2 + in multi-heavy metals solutions, while wheat straw biochar from gasification showed the highest removal efficiency of methylene blue (96.28%). Dissolved phosphorus and magnesium participated in the precipitate forming with heavy metals and K played an important role in ion exchange with heavy metals.Display Omitted
Keywords: Pyrolysis; Biochar; Environment; Agro-residue; Pollutants;
Follow-up research of ultraviolet catalyzing vaporized H2O2 for simultaneous removal of SO2 and NO: Absorption of NO2 and NO by Na-based WFGD byproduct (Na2SO3) by Runlong Hao; Shuo Yang; Yi Zhao; Yaoyu Zhang; Bo Yuan; Xingzhou Mao (64-69).
In the previous work, gas phase oxidation of NO was completed through a method of ultraviolet catalyzing vaporized H2O2, and the results were satisfactory. While the problem of how to effectively absorb NO2 and NO had not yet been studied, this paper was attempted to carry out the absorption of NO and NO2 by various absorbents. The experimental results indicated that Na2SO3 was the best absorbent, and the effects of some key factors on the simultaneous removal were assessed, such as the concentration of Na2SO3, the reaction temperature, the solution pH, the concentration ratio of NO2 to NO, the coexistence gases SO2 and O2, and the conventional anions. Under the optimal conditions, the efficiencies of SO2, NO2 and NO were 99.2%, 89% and 78% respectively. The alkaline atmosphere and high temperature were beneficial for NO2 removal. An appropriate amount of SO2 could promote the removal of NO2 and NO. O2 exhibited an inhibition on removing NO2 and a promotion on removing NO. Sulfate was demonstrated as a promoter for NO removal. Bicarbonate and nitrite were favorable for NO2 removal. The products were identified as sulfate and nitrite based on the characterization by XRD, the reaction mechanism was speculated finally.
Keywords: NO2; NO; SO2; Na2SO3 absorption; Coal-fired flue gas;
One-step synthesis of highly efficient CaO-based CO2 sorbent pellets via gel-casting technique by Yingchao Hu; Wenqiang Liu; Yang Peng; Yuandong Yang; Jian Sun; Hongqiang Chen; Zijian Zhou; Minghou Xu (70-77).
The traditional development of CaO-based sorbents to be used in calcium looping process (CLP) consists of two steps: producing powders with improved cyclic performance by sorbent modification, followed by the subsequent granulation. However, this traditional routine is complicated and energy-consuming. Moreover, the improved performance would be weakened again during the granulation process. Hence, the implement of the modification and granulation within one step to produce CaO-based sorbents is of significant importance for CLP. This work, for the first time, proposes a simple and facile gel-casting technique to achieve the one-step synthesis of highly-efficient CaO-based sorbents pellets. The pellets modified with microcrystalline cellulose (CaO-MC) achieved considerable CO2 capture capacity of ~ 0.48 g CO2/g sorbent at the 25th cycle under the mild calcination condition and retained relatively excellent performance of 0.41 g/g over 25 moderate cyclic tests, higher than those of the unmodified pellets (CaO-pellet). The decomposition of microcrystalline cellulose in CaO-MC does not change the cubic crystal structure of CaO, but brings more pores that contribute a lot to its superior CO2 capture performance. Moreover, all synthesized pellets possess good attrition resistance, indicating the applicability of the prepared pellets to the application in CLP.Display Omitted
Keywords: Gel-casting technique; CaO pellet; One-step synthesis; CO2 capture;
H2S removal by peroxo heteropoly compound/ionic liquid solution by Xinpeng Liu; Rui Wang (78-85).
In this work, five peroxo heteropoly compounds (PHPCs) were synthesized and dissolved in four ionic liquids (ILs) to remove H2S. The Fourier transform infrared (FT-IR) spectrum, Raman spectrum, elemental analysis, Nuclear Magnetic Resonance (NMR) and X-Ray Diffraction (XRD) have demonstrated the successful synthesis of PHPC. Besides, the PHPC and IL were characterized by Thermogravimetry analysis (TGA). The desulfurization results showed that cetyltrimethylammonium peroxophosphomolybdate dissolved in 1-N-butyl-3-methylimidazolium bicarbonate has the best H2S removal capacity. Condition optimization experiments showed that a low H2S concentration and high PHPC concentration is in favor of H2S removal. The optimal absorption temperature is 95 °C at which the H2S removal efficiency could maintain nearly 100% for 2 h. The desulfurization product has been proved to be sulfur. The regeneration experiment showed that the desulfurization capacity of absorbent is weakened after regeneration because of the loss of peroxide. These results indicate that PHPC/IL solution has the potential to remove H2S.The cetyltrimethylammonium peroxophosphomolybdate was synthesized and dissolved in ionic liquid, 1-N-butyl-3-methylimidazolium bicarbonate, to remove H2S. The H2S removal efficiency can maintain nearly 100% at 95 °C for 2 h. The desulfurization product is proved to be sulfur.Display Omitted
Keywords: Peroxo heteropoly compound; Ionoc liquid; H2S; Oxidation; Absorption;
Identification of the structural characteristics of the asphaltenes in the tetrahydrofuran-microwave-extracted portions from two Chinese coals by Liangping Zhang; Song Hu; Qindong Chen; Hengda Han; Lingfeng Xiao; Jun Xu; Long Jiang; Kai Xu; Sheng Su; Yi Wang; Jun Xiang (86-92).
This work aimed to evaluate the detailed chemical structures of the asphaltenes in the tetrahydrofuran-microwave-extracted portions from two Chinese coals, namely, Shenfu and Zhundong coal (SF, ZD) and to clarify their characteristics on chemical composition at molecular level. Based on the analyses of diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) and Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), the detailed chemical structure of a series of basic and non-basic nitrogen- and oxygen-containing class species in the asphaltenes were clarified. The results revealed that condensed nitrogen-containing alkylaromatic structures with amidogens (1–3) were the main structure units in N4Oy (y = 0–2) class species due to the high double bond equivalent (DBE) values for both the asphaltene from SF (ASF) and the asphaltene from ZD (AZD). Acidic O2–O7 class species with two or three aromatic rings were the main structure units, among which O4 and O2 class species had the highest relative abundances (RAs) in ASF and AZD, respectively. Acidic oxygen-containing components in AZD had narrower range of DBE and carbon number and mainly consisted of aromatic structure units with two rings. On the contrary, the average DBE values of O4–O7 class species in ASF had positive relationship with oxygen atom number which could be attributed to the introduction of phenol groups. The results provided more detailed information on the structural characteristics of polar and aromatic-rich components of mobile phase in coal.Display Omitted
Keywords: FT-ICR MS; Mobile phase; Basic nitrogen compounds; Acidic oxygen compounds;
PVP-assisted synthesis of unsupported NiMo catalysts with enhanced hydrodesulfurization activity by Huan Liu; Quanzhen Liu; Jianzhong Zhang; Changlong Yin; Yuxin Zhao; Shumeng Yin; Chenguang Liu; Wanfu Sun (93-101).
The effect of polyvinyl pyrrolidone (PVP) on the physicochemical properties and catalytic activities of unsupported NiMo catalysts was studied. The NiMo catalyst precursors were synthesized by a PVP-assisted chemical precipitation method, by adding various contents of PVP to a Ni- and Mo-containing solution. A series of techniques, including CHSN analysis, XRF, XRD, N2 adsorption-desorption, FT-IR, SEM, TG-DSC, TPR, and XPS, were used to characterize the NiMo oxide precursors and sulfided catalysts, and the catalytic activities were tested in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The characterization results revealed that PVP was efficiently removed due to low contents in the synthesis and high solubility in water. The pore properties and hysteresis loop, the agglomeration of the nanoparticles, and the reducibility of the NiMo precursor were affected by the introduction of PVP, while the phases of the precursors and the thermal stabilities were little changed. Ni3S2 and MoS2 phases were observed in the sulfided catalysts. The catalysis results revealed that the hydrogenation pathway was predominant in the HDS of DBT. A NiMo catalyst synthesized with 0.5 g PVP showed a higher conversion of DBT than the other NiMo catalysts, possibly due to efficient formation of the ‘NiMoS’ active phase. This facile, scalable, and cost-effective route to prepare unsupported NiMo catalyst with enhanced HDS activities would be attractive in industrial applications.Display Omitted
Keywords: NiMo catalyst; Hydrodesulfurization; PVP; Unsupported catalyst; Uniform nanoparticle;
Demonstration of mitigation and utilization of ventilation air methane in a pilot scale catalytic reverse flow reactor by Zhikai Li; Zhiwei Wu; Zhangfeng Qin; Huaqing Zhu; Jianbing Wu; Ruiyi Wang; Lijun Lei; Jiangang Chen; Mei Dong; Weibin Fan; Jianguo Wang (102-108).
The mitigation and utilization of ventilation air methane was demonstrated in a pilot scale catalytic reverse flow reactor. A kind of non-noble metal oxide catalyst of 1.8 m3 was loaded and lean methane with a concentration of 0.2–1.0 vol% and a maximum feed flow rate of 800 m3/h was processed. The schemes of reactor control and heat recovery, viz., a simple logic-based controller plus hot gas withdrawal from reactor center, as proposed previously by simulation, were verified in this pilot scale reactor. The results prove that the autoregulative time to switch the gas flow direction will drop quickly to zero if a large amount of hot gas is withdrawn from the reactor by using the traditional method. The switching time has a great influence on the heat recovery efficiency, whereas the amount of hot gas removed out of the reactor impacts significantly on the reactor stability. All these experimental observations are in line with the simulation results. The long term operation proves the feasibility of hot gas withdrawal with a heat recovery efficiency of about 56% and the reliable performances of the non-noble metal catalyst in lean methane oxidation with a methane conversion over 90%. These results prove that the catalytic reverse flow reactor and control schemes used in this work are quite effective in the mitigation and utilization of lean methane.A pilot scale catalytic reverse flow reactor was demonstrated for the mitigation and utilization ventilation air methane; the schemes of reactor control and heat recovery proposed previously by simulation were verified.Display Omitted
Keywords: Ventilation air methane; Reverse flow reactor; Non-noble metal catalyst; Logic-based controller; Heat recovery; Hot gas removal;
Investigation of the physical characteristics of washed hydrochar pellets made from empty fruit bunch by Ilman Nuran Zaini; Srikandi Novianti; Anissa Nurdiawati; Adrian Rizqi Irhamna; Muhammad Aziz; Kunio Yoshikawa (109-120).
In this study, the comparison of the pellets produced from untreated EFB, the hydrothermally treated empty fruit bunch (HTT-EFB) and washed HTT-EFB was performed. The pelletization of the raw EFB, HTT-EFB, and washed HTT-EFB was conducted using a single pellet making device. In experiments performed at room temperature under a densification pressure of 150 MPa, the physical properties, mechanical strength, durability, and hydrophobicity of the produced pellets were then evaluated. Scanning electron microscope (SEM) analysis was also performed to investigate the binding mechanisms within the pellets. The results showed that the washed HTT-EFB pellets had higher mechanical strength and durability than the HTT-EFB or raw EFB pellets. The HTT-EFB pellets also demonstrated hydrophobic behavior against moisture exposure. However, the washed HTT-EFB pellets required higher compaction energy than the other pellets. From this analysis, it was determined that the changes in the composition of EFB biomass owing to HTT and the washing process regulate pelletization behavior and affect the binding mechanism during pelletization. In addition, the combustion performance of treated EFB samples showed significant improvements as it has higher ignition temperatures with more uniform combustion profiles as shown in the data obtained from TGA analyser. This research demonstrated that the combination of HTT, washing, and pelletization cotreatment is a promising method for upgrading EFB into energy-dense, durable, and homogeneous hydrophobic solid fuel.
Keywords: Hydrothermal treatment; Washing process; Hydrochar; Biomass pellet; Durability;
Characterization and behavior of water in lignocellulosic and microalgal biomass for thermochemical conversion by Svetlana Bikbulatova; Arash Tahmasebi; Zhiqiang Zhang; Jianglong Yu (121-129).
Behavior and nature of water in biomass significantly influence the thermochemical conversion processes. This study investigates the characteristics and behavior of water in lignocellulosic and microalgal biomass using differential scanning calorimetry (DSC) and low-temperature X-ray diffraction (XRD) methods. Pine sawdust (PS), peanut shell (PT), and microalgae (MA) samples with different water contents were used and analyzed systematically. Freezable free water was detected in all biomass samples through DSC analysis. Different from PS and PT, a shift in the position of freezable free water peaks was observed during freezing process of MA on DSC, which was attributed to the strong hydrophilicity of this biomass. No freezable bound water was observed in the biomass samples. However, significant amount of non-freezable bound water was detected in all biomass samples. The freezing enthalpies of freezable free water in PS, PT, and MA ranged between 319.04 and 297.7 kJ/kg which were in good agreement with that of bulk water. The boundary between freezable and non-freezable water in the biomass samples was clearly defined combining DSC and XRD analyses. The amount of non-freezable bound water in biomass samples directly correlated with the relative concentration of oxygen functional groups in biomass samples.
Keywords: Biomass-water interaction; Low-temperature DSC; Low-temperature XRD; Freezable free water; Non-freezable bound water;
Mechanism of hydrogen transfer and role of solvent during heating-up stage of direct coal liquefaction by Ben Niu; Lijun Jin; Yang Li; Zhiwei Shi; Yueting Li; Haoquan Hu (130-135).
In this paper, the liquefaction of a Bulianta coal, from China Shenhua Group, was carried out in a hydrogen donor solvent, tetralin, or a non-hydrogen donor solvent, 1-methylnaphthalene, with or without catalyst to clarify the mechanism of hydrogen transfer. And roles of solvent and a nano-size iron catalyst from Shenhua Group in the heating-up stage of DCL were also investigated by using mixed solvent of decalin, phenanthrene, pyrene or fluoranthene and tetralin. The results show that tetralin inhibits the reaction of coal macromolecule to oil and the transfer of H2. The major transfer approach of H2 may be directly from H2 to coal rather than via the hydrogen donor solvents in the presence of the nano-sized iron catalyst. In the heating-up stage of DCL, the major role of solvent is to provide activated hydrogen for coal. High dissolving capability of the liquefaction solvent that has high enough hydrogen donor capacity is beneficial for improving liquefaction performance. The dominant function of the catalyst is to promote the activation of H2, which can improve coal liquefaction performance in the heating-up stage of DCL.
Deep oxidative desulfurization catalyzed by (NH4)5H6PV8Mo4O40 using molecular oxygen as an oxidant by Meng Shi; Dan Zhang; Xia Yu; Yiming Li; Xiaohong Wang; Wu Yang (136-142).
(NH4)5H6PV8Mo4O40 (NPVMo) was evaluated in oxidation desulfurization of dibenzothiophene (DBT), benzothiophene (BT) and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) in a model oil using O2 as an oxidant. By controlling the reaction conditions, sulfur contents in the model oil were decreased from 500 ppm to < 1 ppm corresponding to DBT, BT and 4, 6-DMDBT with almost 100% yield of sulfone, respectively. Meanwhile, thiophene is one of the main sulfur species in gasoline, which is difficult to be oxidized in conventional oxidative processes and to be removed from fuels. Noteworthily, thiophene was oxidized efficiently at 97% conversion catalyzed by NPVMo and O2 as oxidant. Such high activity was attributed to the electron transfer between NPVMo and DBT. Meanwhile, NPVMo acted as a heterogeneous and stable catalyst and could be recycled ten times with a slight decrease in activity in the model oil. More importance was that NPVMo was also available for deep desulfurization for FCC gasoline and diesel to obtain almost clear products with extremely lower sulfur content (2.29 and 9.43 ppm, respectively) without formation of by-products of oxidation to loss their octane values.Display Omitted
Keywords: Oxidation; Desulfurization; Oxygen; Organic sulfur; Polyoxometalate;
Mechanical degradation of biomass wood pellets during long term stockpile storage by Shalini Graham; Carol Eastwick; Colin Snape; Will Quick (143-151).
This paper quantifies and assesses the mechanical degradation of white wood and steam exploded wood pellets in indoor and outdoor stockpile storage over a twenty-one month period in the UK. The indoor stored steam exploded wood pellets on the surface of the pile only exhibited a 3% decrease in durability after twenty months in storage. The outdoor stored pellets demonstrated much higher levels of mechanical degradation. In the summer period with high relative humidity and temperature, the durability of pellets sampled from the surface of the pile dropped from 92 to 22% after three months in storage with a durability of 10% measured after nine months in storage. The degradation of the pellets from the middle of the pile was more gradual and less severe with a maximum durability drop of 34%. The impact on mechanical properties was significant for the indoor stored white wood pellets with pellets quickly degrading to dust. This study shows that while steam exploded pellets could be stored in covered storage, white wood pellets require a fully enclosed storage environment. Short term outdoor storage of steam exploded pellets could be considered if extended periods of low rainfall and relative humidity can be reliably predicted.
Keywords: Wood; Pellet; Steam explosion; Storage; Degradation;
Effect of supports over Pd/Fe2O3 on CO oxidation at low temperature by Li Wang; Chunhua Pu; Lele Xu; Yafeng Cai; Yanglong Guo; Yun Guo; Guanzhong Lu (152-157).
Pd/Fe2O3 catalysts were prepared by deposition-precipitation method and investigated for CO oxidation. Compared with Pd/α-Fe2O3, Pd/γ-Fe2O3 exhibited the higher CO oxidation activity, and CO completely oxidation temperature was obtained at 0 °C. CO oxidation occurred through the dual sites mechanism, namely CO adsorbed on Pd species and O activation on the support. The close contact between Pd and γ-Fe2O3 enhanced the redox recycle between Fe3 + and Fe2 + species, which played a decisive role in oxygen activation. The excellent performance in oxygen activation efficiently accelerated the rate-determining step in CO oxidation. The accumulated carbonate and hydrocarbonate species on α-Fe2O3 blocked the oxygen activation which resulted in the low activity of Pd/α-Fe2O3 in CO oxidation.Display Omitted
Keywords: CO oxidation; Fe2O3; Low temperature; Deactivation;
Magnetically responsive catalytic sorbent for removal of Hg0 and NO by Tiantian Cao; Zijian Zhou; Qian Chen; Zhen Li; Shengming Xu; Jianlong Wang; Minghou Xu; Teresa Bisson; Zhenghe Xu (158-169).
A novel class of magnetically responsive catalytic sorbents are proposed and synthesized with a potential application to simultaneous removal of Hg0 and NO at low temperature from the flue gases of coal-fired power plants. The catalytic sorbent consists of magnetite (Fe3O4), molecular sieve (HZSM-5), supported silver nanoparticles and catalytically reactive component of V2O5. Each of these materials provides a unique function for the purpose of capturing mercury, removing NO, and separation from fly ash. After separation from the fly ash, the spent sorbent can be regenerated and reused, leaving an uncontaminated fly ash product. The successful synthesis as designed was confirmed and properties of the catalytic sorbent were characterized by several methods. The synthesized catalytic sorbent was able to completely capture Hg0 at 150 °C with a capture capacity as high as 32.4 μg·g−1, while achieving 84% removal of NO at 150 °C. Even at a relatively high space velocity, the catalytic sorbent achieved 97% Hg0 and 80% NO removal simultaneously, while maintaining a good stability after repetitive regeneration and recycle. The magnetically responsive catalytic composite was shown to be a promising candidate for multi-pollutant emission control from coal-fired power plants.Display Omitted
Keywords: Coal combustion; Hg removal; Silver nanoparticle; Vanadium pentoxide; HZSM-5; DeNOx;
Characterization of organic nitrogen and sulfur in the oil shale kerogens by Qing Wang; Qi Liu; Zhi-Chao Wang; Hong-Peng Liu; Jing-Ru Bai; Jiang-Bin Ye (170-177).
Organic nitrogen and sulfur species along with carbon structural features in the five different oil shale kerogens were characterized by solid-state 13C NMR, XPS, and XRD techniques. Results indicate all the five kerogens contain aliphatic carbons in large amounts, aromatic carbons and small quantities of carbonyl and carboxyl carbons. Increased metamorphism results in increase in the number of aromatic carbons and corresponding decrease in that of aliphatic carbons. All kerogens contain five forms of organic nitrogen: pyridinic nitrogen, amine nitrogen, pyrrolic nitrogen, quaternary nitrogen, and nitrogen oxides. Relative amount of pyrrolic nitrogen is the highest and the majority of organic nitrogen exists as pyrrolic and quaternary nitrogens in comparable relative abundances, both accounting for > 70%. With increase in the number of aromatic carbon, the relative number of pyridinic nitrogen increases and that of amine nitrogen decreases. Forms of organic sulfur include aliphatic sulfur, aromatic sulfur, sulfoxide, and sulfone in all the kerogens. A small amount of inorganic pyrite sulfur is also present. Most of the organic sulfur (> 70%) exists as aromatic sulfur and sulfone. With increasing amount of aromatic carbon, the relative amount of aromatic sulfur increases significantly, whereas that of aliphatic sulfur decreases.
Keywords: Kerogen; Organic nitrogen and sulfur; XPS;
NiAlZrW hydrodesulfurization catalysts derived from tungstate intercalated NiAlZr layered double hydroxides by Hao Wang; Zhouxi Yang; Xuchun Zhan; Yan Wu; Min Li (178-184).
A series of tungstate-intercalated NiAlZr layered double hydroxides (LDHs) with different Zr contents were prepared by an ion exchange method. The LDHs were further calcined at 450 °C to obtain NiAlZrW mixed metal oxides as hydrodesulfurization (HDS) catalysts. The properties of the LDHs and catalysts were characterized and their activity was evaluated by the HDS of dibenzothiophene (DBT). The results show that W7O24 6 − anions are successfully intercalated in the interlayer gallery. Upon calcination, tungsten species are highly dispersed on the catalysts even at the tungsten oxide content above 50 wt%, owing to the peculiar layered structure of LDHs. On the LDHs-derived catalysts, amorphous and dispersed NiWO4 species are formed due to the reaction between Ni in the layer and tungstate in the interlayer during calcination. The introduction of Zr could further facilitate the formation of highly dispersed NiWO4 species and improve their reducibility by weakening the strong W―O―Al interaction. This is responsible for the superior HDS activity and higher hydrogenation selectivity of Zr-containing catalysts derived from LDHs, in comparison with those of Zr-free catalysts and the catalyst with the same metal contents prepared by the impregnation method. The present work may offer a convenient approach to prepare active HDS catalysts by provoking the formation of NiWO4 species with both high dispersion and reducibility.Tungstate intercalated NiAlZr layered double hydroxides (LDHs) are synthesized by ion exchange method and their calcined oxides are used as HDS catalysts. Highly dispersed and amorphous NiWO4 species are formed on the catalysts. The introduction of Zr could facilitate the formation of NiWO4 and improve the reducibility by weakening the interaction between W and Al, leading to superior HDS activity.Display Omitted
Keywords: Layered double hydroxides; Hydrodesulfurization; Catalysts; Zirconia;
Highly active and stable Ni supported on CNTs-SiO2 fiber catalysts for steam reforming of ethanol by Natthawan Prasongthum; Rui Xiao; Huiyan Zhang; Noritatsu Tsubaki; Paweesuda Natewong; Prasert Reubroycharoen (185-195).
In this research, a new kind of carbon nanotubes-silica fibrous composite (CNTs-SF) was successfully synthesized by the steam reforming of ethanol over a Ni/silica fiber catalyst prepared by electrospinning technique. The fibrous composite was then used as a support for the ethanol steam reforming by loading nickel at 5 and 10 wt%. The prepared catalysts were characterized by BET, SEM, TEM, XRD, TPR, and TG/DTG. The reaction performance of the NiCNTs-SF catalysts was investigated and compared with the Ni/silica fiber (NiSF) and Ni/silica porous (NiSP) catalysts. The effect of temperatures on the ethanol conversion and product distribution was studied in the range of 300 and 500 °C. The NiCNTs-SF catalyst exhibited the best performance in term of stability and high activity at lower reaction temperature. The outstanding performance of the NiCNTs-SF catalyst could be associated with highly metallic dispersion and easily accessible to the reactants.
Keywords: Nickel-based catalyst; Steam reforming of ethanol; Silica fiber; Silica porous; Carbon nanotubes;
A review on the pretreatment of lignocellulose for high-value chemicals by Hongyan Chen; Jinbao Liu; Xing Chang; Daming Chen; Yuan Xue; Ping Liu; Hualin Lin; Sheng Han (196-206).
Pretreatment is an important process to transform lignocellulosic biomass to high-value chemicals. This process potentially provides economic sustainability, which is challenged by energy crisis and environmental pollution. Pretreatment is mainly applied to improve the digestibility of cellulose by increasing enzyme accessibility. Different lignocellulosic biomasses require various pretreatment processes and conditions depending on process configurations selected for subsequent hydrolysis and fermentation steps. In this article, studies on the pretreatment of lignocellulose for high-value chemicals were reviewed. The relative advantages of various pretreatment processes, including physical, chemical, physicochemical, and biological methods, were also assessed in economic perspectives. Existing problems and development potential were also discussed. This review provides a theoretical basis for future research on lignocellulosic biomass for chemical applications.
Keywords: Pretreatment process; Lignocellulose; Chemicals;
The relationship between benzene carboxylic acids from coal via selective oxidation and coal rank by Fan Yang; Yucui Hou; Weize Wu; Qian Wang; Muge Niu; Shuhang Ren (207-215).
The oxidation of coal to produce benzene carboxylic acids (BCAs) was widely researched. However, the relationship between coal rank and BCAs from coal is unknown. In this study, 8 kinds of coal with different ranks were investigated and the effect of coal rank on the BCA yield distribution was studied. The results indicate that with the increase of coal rank, the yield of BCAs increases, and the structure of coal becomes more and more difficult to be degraded. In addition, BCA yield distribution varies significantly with the increase of coal rank. The results of 13C NMR show that with increasing coal rank, the fraction of aromatic carbon (f a) and mole fraction of aromatic bridgehead carbon in aromatic carbon (X b) both are increased gradually, and alkyl-substituted degree of aromatic ring (δ) and average methylene chain length (C n) both are decreased. More and more parent structures of phthalic acid, trimellitic acid, hemimellitic acid and prehnitic acid exist in the coal with the increase of coal rank. When the carbon content of coal is > 87%, the structure of coal has a mutation property that more and more circular catenations of aromatic rings exist in the structure of coal.
Keywords: Benzene carboxylic acids; Coal rank; 13C NMR; Oxidation; Coal structure;
Secondary comminution of wood pellets in power plant and laboratory-scale mills by Anna Trubetskaya; Yunus Poyraz; Roman Weber; Johan Wadenbäck (216-227).
This study aims to determine the influence of mill type and pellet wood composition on particle size and shape of milled wood. The size and shape characteristics of pellets comminuted using power plant roller mills were compared with those obtained by using laboratory-scale roller- and hammer mills. A 2D dynamic imaging device was used for particle characterization. It was shown that mill type has a significant impact on particle size but an almost negligible effect on the shape of milled wood. Comminution in the pilot plant using a Loesche roller mill requires less energy than using a hammer mill, but generates a larger fraction of coarse particles. The laboratory-scale roller mill provides comparable results with the power plant roller mill with respect to particle size and shape.
Keywords: Pellets; Hammer mill; Roller mill; Particle size; Shape;