Abstract: The effect of kaolin on the ash fusion characteristics of high alkali Xinjiang Zhundong coal was investigated by quantum chemistry calculation and experimental measurement methods. The results show that the ash fusion temperature is increased significantly by adding kaolinite; the ash fusion temperature increases rapidly at first with the increase of kaolinite content added in the Zhundong coal and then levels off when the fraction of kaolinite exceeds 10%. By adding kaolin in the Zhundong coal, the content of minerals with a low melting point (1 100-1 200 ℃), such as anorthite and anhydrite, is reduced, whereas mullite is found at 1 200-1 300 ℃. O (26), Si (6), O (22) and Si (8) atoms in the kaolinite molecular structure exhibit relatively high reactivity; Al-O bond, which is connected with O (26) and O (22), can be ruptured by reacting with Fe2+ or other metal ions in ash as an electrophilic reagent. The O2- of alkali oxides in ash, such as Na2O and CaO, can react as a nucleophilic reagent with Si (6) and Si (8) in kaolinite, breaking the oxygen bridge bond of Si-O-Si in kaolinite.
Abstract: Based on classification of silica and alumina content and silica alumina ratio in coal ash, optimized prediction models of coal ash melting point and viscosity related to ash components were built. Their relationship in a wide range of ash components was also discussed. An ash fusion temperature prediction model based on liquidus temperature from FactSage Thermodynamic software demonstrates accuracy improvement with error of less than ±40 ℃ and deviation of 25 ℃. The combination of Urbain and Roscoe model results in viscosity prediction error between prediction and experiment results within ±0.1 for relative low viscosity and ±0.2 for relative high viscosity. The results show that components classification model obtains better results than wide-covered model. Thus a better understanding of ash fusion mechanism is provided and gives reasonable guidance for blending and additives added to coal.
Abstract: The distribution of products was preliminarily studied based on a process of low rank coal mild liquefaction at 390-450 ℃ coupled with carbonization. The characteristics of liquid product and semi-coke were analyzed. The results showed that the organic liquid product yield is 23.44%-33.26% (daf, coal) and the semi-coke yield is 49.56%-68.72% (daf, coal). The water content of liquid product is 1.30%-2.49%. The n-hexane soluble content of organic liquid product is higher than 98.95% with no solid particles in liquid product. The carbon content of semi-coke obtained is 87.87%-93.45% (daf), some semi-cokes have the characteristics of strong caking property. There is a close correlation between caking property and asphaltene content of semi-coke.
Abstract: Two-step pyrolysis of soybean stalk was investigated using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that with the increase of the first-step pyrolysis temperature (t1), the total peak area of the first-step products becomes higher. However, for the second-step, the total peak area decreases gradually with the increase of t1. The products in the first-step pyrolysis have higher contents of acids, ketones and furans when t1 is 400 or 450 ℃. This is because that the products are originated from cellulose and hemicellulose. The content of hydrocarbon products in the second-step is more than 20% when t1 is 450 or 500 ℃. With two-step pyrolysis some products with high content can be obtained in the first or second step, respectively, such as acetic acid, furfural, guaiacol, methylbenzene and benzene etc., thus preliminarily achieving the selective pyrolysis of biomass.
Abstract: The 2% Fe modified HZSM-5 zeolite catalysts were prepared by ion-exchange and characterized by laser particle size analyzer, specific surface area and pore size analyzer, and X-ray diffraction (XRD) to investigate the pore and surface properties. The catalytic pyrolysis of wood was carried out at 550 ℃ to get the maximum oil yield. After pyrolysis, the bio-oil was separated to the lighter (upper layer) and heavier component (bottom layer). The results indicate that with Fe modified HZSM-5 catalysts, the bio-oil yield increases significantly (maximum 7%) the same as that of the lighter one, while the heavier one is nearly constant. Ketones and furans in the lighter oil decreases, while acids and phenols increase significantly; in the heavier oil, ketones and furans decreased dramatically, phenols and naphthalenes increase significantly. The Fe modified HZSM-5 catalysts play an important role in pyrolysis of wood dusts, and have a critical influence on oil yield because the modified catalysts promote the shape-selective modifying of the initial pyrolysis steam and inhibit the secondary coking reaction of steam. The product tends to much lighter bio-oil component and lower oxygen content.
Abstract: A series of NiO@SiO2 core-shell catalysts were prepared using modified Stöber-method. Their catalytic performances in methanation of syngas were investigated in slurry reactor at 320 ℃. The catalysts before and after reaction were characterized by XRD, TEM, XPS, N2-physisorption, etc. It was found that the NiO@SiO2 core-shell samples had well-shape morphologies and relatively uniform scale. The catalyst test revealed that the methanation activity of these catalysts decreased dramatically with increase of core particle size. The three catalysts with distinct size of core and shell showed remarkably rapid deactivation in the initial period of 20 h and then deactivated slowly during the following reaction, while their CH4 selectivity maintained at about 80%. Void-shell was formed during the reaction probably because easy-migrated Ni (CO)x species were generated. Apparently, it was concluded that increase of core particle size, decrease of BET surface area and pore volume, and abatement of mesopores within 3-5 nm in the shell were responsible for the deactivation of these core-shell catalysts based on the characterization of catalysts.
Abstract: A series of MCM-41-supported NixP catalysts was prepared by the solvothermal method using low-price triphenylphosphine as phosphorus material and tri-n-octylamine as coordinating liquid reaction system. They were characterized with X-ray diffraction, N2 sorption, CO sorption, X-ray photoelectron spectroscopy and transmission electron microscopy techniques. The effects of initial P/Ni molar ratio on their structures and hydrodesulfurization performances were investigated in a lab-scale continuous flow fixed-bed reactor by feeding 1% of dibenzothiophene (DBT) in decahydronaphthalene. It was shown that Ni12P5 was primarily formed with a small amount of Ni2P at the initial P/Ni molar ratio of 0.5. When the initial P/Ni molar ratio was higher than 0.5, pure Ni2P phase was generated, and its crystal size decreased, and thus, its dispersion increased with the increase of initial P/Ni molar ratio. At 613 K, 3.0 MPa, H2/oil ratio of 500 (volume ratio), and weight hourly space velocity of 2.0 h-1, the DBT conversion nearly reached 100% on both the Ni-P (6)/MCM-41 and the Ni-P (10)/MCM-41 samples.
Abstract: A series of NiMo/γ-Al2O3 catalysts with different NiO loadings were prepared and characterized by XRD, BET, 27Al-NMR, Py-IR and HRTEM. The activity of these NiMo/γ-Al2O3 catalysts in the hydrodesulphurization (HDS) of dibenzothiophene (DBT) was evaluated in a high pressure micro reactor; the interaction between Ni promoter and γ-Al2O3 support as well as its effect on the nanostructure of active MoS2 phase and HDS performance was then investigated. The results indicate that Ni promoter prefers to interact with the tetra-coordinated unsaturated aluminum sites on the support surface. With the increase of NiO loading, the average number of stacking layers for the MoS2 clusters in the sulfided NiMo/γ-Al2O3 catalysts is increased at the expense of the average length. As the slim MoS2 clusters are more active for the HDS of DBT, the addition of Ni promoter is then effective to enhance the catalytic activity of NiMo/γ-Al2O3 in HDS, but may lead to a slight decrease in the hydrogenation selectivity.
Abstract: The γ-Al2O3 supported Ni-W catalysts with different metal contents for the hydroprocessing of low and middle-temperature coal tar were prepared and characterized by the X-ray diffractogram (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of NH3 (NH3-TPD), N2 adsorption and high resolution transmission electron microscopy (HRTEM). The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) performances of the catalysts were evaluated by using low and middle temperature coal tar. The results show that the sulfidation degree of the catalysts increases with increasing metal content within a certain range, while the amount of total acid that mainly consists of intermediate acid decreases. The HDN activity of the catalysts with Ni/W atomic ratio of 0.786 increases initially and reaches an optimum value at 24% WO3, and then decreases, while the HDS activity increases gradually.
Abstract: The NiMoP/γ-Al2O3 catalyst was prepared through a multi-step impregnation method and characterized by inductively coupled plasma mass spectrometry (ICP-MS), N2 adsorption-desorption, transmission electron microscope (TEM) and H2 temperature programmed reduction (H2-TPR). The catalyst with 4%Ni is determined to be the best one with optimum component proportion by the tests with model compounds in a fixed-bed reactor. The coal tar hydrogenation was conducted over the optimum catalyst. The results reveal that the removal of carbolic oil can promote the removal of S and N and the saturation of aromatics.
Abstract: Ni-Smx/SiC (x=0, 2%, 3%, 4%, 5%, 7%) catalysts were prepared by impregnation method, and the performance of catalysts for carbon dioxide reforming of methane were tested in a fixed bed reactor. The catalysts were characterized by BET, ICP, XRD, H2-TPR, TG-DTA, XPS and TEM. The results showed that Ni-Sm5/SiC had excellent catalytic activity and stability, and the least amount of coke deposition. The addition of samarium effectively enhanced the interaction of metal active component and support, and reduced the formation of coke and therefore improved the catalyst stability.
Abstract: Pt-SnE/Mg (Al) O catalyst was prepared by anion exchange method with hydrotalcite as the support. The Pt-SnE/Mg (Al) O catalyst was characterized by XRD, nitrogen sorption, CO-TPD and TEM; its catalytic performance in the dehydrogenation of ethane and propane was compared with that the Pt-SnI/Mg (Al) O catalyst obtained by impregnation method. The results indicate that under the same reaction conditions, the conversions of ethane over the Pt-SnE/Mg (Al) O and Pt-SnI/Mg (Al) O catalysts are 12.2% and 3.1%, respectively, whist the conversions of propane over these two catalysts are 38.7% and 26.4%, respectively. Such results illustrate that the Pt-SnE/Mg (Al) O catalyst prepared by the anion exchange method is obviously superior to the Pt-SnI/Mg (Al) O catalyst prepared by the impregnation method in terms of catalytic activity and stability for alkane dehydrogenation.
Abstract: A flower like Pd layer was synthesized through galvanic displacement reaction on Ni-YSZ (yttria stabilized zirconia) anode at room temperature. The morphology of as prepared Pd catalyst was characterized by various techniques. It was shown that three dimensional Pd nanoflowers were formed via nanorods on the Ni-YSZ anode. With Pd nanoflowers as a functional layer of the Ni-YSZ anode, the cell exhibited much higher peak power density and better operation stability in ethanol than that made with conventional Ni-YSZ anode. This study demonstrated that galvanic displacement reaction is a promising way to prepare nanostructured metal catalyst as a result of depressing the carbon deposition in Ni-based anode and improving its output in alcohol fuels.
Abstract: A series of PtCu/C catalysts (with a CuPd loading of 20%) were prepared by ethylene glycol (EG) reduction method with different metal precursors, viz., CuSO4/CuCl2 and K2PtCl4/H2PtCl6. The morphology, structure and electrochemical performance of as-prepared PtCu/C catalysts were characterized by high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV) and liner sweep voltammetry (LSV) techniques. The results indicate that the PtCu/C catalyst prepared with CuSO4 and K2PtCl4 as precursors exhibit highest electrochemical performance, in which metal particles with a mean size of 2.3 nm are uniformly dispersed on the carbon support. Such a PtCu/C catalyst has an electro-chemical surface area (ECSA) of 73.0 m2/gPt and a mass activity (MA) of 126 mA/mgPt, both higher than the commercial Pt/C catalyst.
Abstract: A novel method of hydrogen production from oxidation of coal slurries using the mutual transformation of Fe3+ and Fe2+ was studied. At the first step, in a boiling kettle coal slurries are oxidized by Fe3+ into Fe2+. Then Fe2+ is oxidized in an anode chamber and hydrogen is produced in cathode chamber. The two steps are combined to form a cycle to produce hydrogen. Nine cycles were performed at constant voltage (1 V) and the current densities and accumulated electric quantities at each cycle were investigated. The coal samples before, during and after reaction were analyzed with scanning electron microscope (SEM), BET specific surface area, thermal gravity (TG) and Fourier transform infrared spectrum (FT-IR). The results show that hydrogen production of "two-step" cycle processes has a higher reaction rate. The initial current density is about 60 mA/cm2, while that of traditional "one-step" process is usually less than 10 mA/cm2. The characterizations give a clear understanding on the changes of coal particles in morphology, structure and composition during the cycles, and also reveal the reaction mechanism of mutual transformation between Fe3+ and Fe2+.
Abstract: NH4NO3 and (NH4)2S2O8 with different mass fractions were used as electrolyte to modify the anodic carbon cloth used in a double chamber microbial fuel cell. Using some restaurant wastewater as the anode substrate and the mixed solution of K3[Fe (CN)6] and NaCl as catholyte, the power generation performance and wastewater treatment effect of a microbial fuel cell with modified anode by different electrolytes were studied. The experimental results show that the microbial fuel cell with modified anode by NH4NO3 and (NH4)2S2O8 has a better power generation performance and sewage treatment effect. The power generating ability and the purifying effect of the microbial fuel cell achieve the optimal state with the steady current density of about 60 mA/m2 and the removal rate of COD of about 42.5% when the (NH4)2S2O8 of 4% mass fraction is used as the modified electrolyte of anode.
Abstract: A series of hierarchical NaY zeolites with different pore size distribution were synthesized by sequential treatment with ethylenediaminetetraacetic acid and NaOH. The structural properties of the as-synthesized hierarchical NaY zeolites were characterized by X-ray diffraction, N2 sorption, SEM and TEM. The adsorption and diffusion performances of benzene on NaY and hierarchical NaY zeolites were studied by frequency response (FR) and intelligent gravimetric analyser (IGA). It was found that the structure of NaY zeolite was remained by suitable acid and base treatment, but the connectivity in the pores was finely tailored. Mesoporous was introduced to reduce the molecular diffusion resistance in the pores, while the larger pore size and connectivity in the mesoporous was more beneficial to diffusion and accessibility of activity site. The adsorption of benzene on NaY was found to be the rate-controlling step. While, the limiting steps for the overall mass transfer processes in the hierarchical zeolites are the diffusion process in the length scale of micropore/mesopore and the mass transfer at the micropore-mesopore molecular exchange rather than the intracrystalline diffusion one in the micropores of the zeolite crystals.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
