Abstract: The effect of moisture adsorption and air pre-oxidation on the spontaneous combustion liability of lignite upgraded was investigated for the purposes of obtaining the characteristics and mechanism of the spontaneous combustion liability during storage outside. By a testing apparatus for spontaneous combustion liability, the crossing-point temperature (CPT) for calculating the aggregative indicator FCC was measured for the fresh samples upgraded at the temperature ranging from 105℃ to 900℃ and for the upgraded samples suffering moisture adsorption and pre-oxidization. The changes of chemical structure were analyzed by Fourier transform infrared spectroscopy and energy dispersive spectrometer, and the evolution of pore structure was identified by physical adsorption experiments, and the difference of wetting heat for moisture absorption was determined by the micro calorimeter. The results show that the spontaneous combustion liability of fresh upgraded lignite is reduced with increasing upgrading temperature. But the adsorbing moisture and pre-oxidation make the spontaneous combustion liability of samples upgraded at 200-500℃ increase obviously comparing with the corresponding fresh upgraded samples. Pre-oxidation can increase the elemental oxygen content and the amount of oxidation active groups on the surface of samples. The oxidation active groups of aliphatic side chains, oxygen-containing functional groups, new free radicals from upgrading process, and the increase of specific surface area after deep upgrading all intensify the pre-oxidation and spontaneous combustion of the upgraded samples. The heat of wetting from adsorbing moisture not only further deepens the pre-oxidation, but also enhances the spontaneous combustion liability remarkably for the upgraded samples adsorbing more moisture.
Abstract: The catalytic gasification performance of Buliangou coal using Ca(OH)2 as catalyst was investigated at 3.5 MPa and 700-800℃ in a pressurized fixed bed. The effect of gasification temperature, Ca(OH)2 loading and loading method on coal steam gasification and methanation reaction were examined. The results show that Ca(OH)2 can enhance the reactivity of char gasification and the formation of CH4. Increasing temperature and Ca(OH)2 loading can heighten the carbon conversion, but Ca(OH)2 loading possesses a saturation point. The gasification reactivity is affected by loading method which determines the Ca(OH)2 dispersion. The coal char loaded with Ca(OH)2 shows a great catalytic activity on methanation reaction and the CH4 content in the product gas increases with the increase of methanation temperature and catalyst loading. The analysis result of coal surface function groups by FT-IR reveals the dispersion mechanism of Ca(OH)2 into the matrix of coal through ion exchange and diffusion, which is a key factor to improve coal char gasification reactivity.
Abstract: Three-dimensionally ordered macroporous (3DOM) LaFe0.7Co0.3O3 perovskite-type oxides were synthesized using a polystyrene (PS) colloidal crystal templating method. The obtained 3DOM LaFe0.7Co0.3O3 perovskites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauere-Emmette-Teller (BET) surface area. Its performance as oxygen carriers in chemical looping steam methane reforming (CL-SMR) to produce syngas (H2 + CO) and hydrogen were investigated in a fixed-bed reactor. The size of PS spheres obviously increases as the styrene addition increases. The calcination temperature is the major factor to affect the prepared 3DOM perovskite. SEM and TEM analysis show that the samples calcined at 500, 800 and 850℃ exhibit good 3DOM structures which collapse when the sample is calcined at 900℃. XRD results suggest that the obtained 3DOM LaFe0.7Co0.3O3 perovskites are pure crystalline. Two kinds of oxygen species, bulk lattice oxygen and surface adsorbed oxygen, are found to exist on the 3DOM LaFe0.7Co0.3O3 perovskites. The surface oxygen contributes to the complete oxidization of methane to CO2 and H2O in beginning of the reaction, while the bulk lattice oxygen tends towards partial methane oxidation to H2 and CO. In the methane conversion step, methane is partially oxidized into syngas at a H2/CO mol ratio close to 2:1 by the 3DOM- LaFe0.7Co0.3O3 in a wide range of the reactions, suggesting that the sample exhibits a good resistance to carbon deposition. In the steam oxidation step, the reduced perovskites are oxidized by steam to generate hydrogen with hydrogen productivity about 4 mmol/g oxygen carriers.
Abstract: The reactivity and structural characterizations of the sintered iron ore in redox cycles were investigated. The sintered return fines were selected as oxygen carriers and the chemical looping combustion was tested in a fluidized bed with a reducing atmosphere of 95% methane. The characterizations of structural and physical properties of the sintered raw materials and the reduced and oxidative regenerated samples were conducted. The results reveal that during the initial oxidation cycle, the oxygen carrying capacity and reaction activity of the sinter are improved remarkably. The specific surface area of the sinter increases significantly in the first 25 cycles, which may be one of the main reasons for the reactivity increase of the sinter. During the recycling process, some cracks are formed on the surface of sintered return fines and gradually get development. The Raman results indicate that the new crystalline phase, lepidocrocite (γ-FeOOH), is formed, which will decrease the oxygen carrying capacity of the oxygen carrier. When the methane is used as the reducing gas, there is no carbon deposition on the surface.
Abstract: Firstly, lignin of palm kernel shell (PKS) and wheat straw (WS) were isolated by enzymatic/mild acidolysis method (EMAL). Then the functional groups and thermal decomposition characteristics of the two EMALs were analyzed with Fourier transform infrared spectroscopy (FT-IR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and TG-FTIR. At last, the Ozawa-Flynn-Wall method was used to calculate the activation energy of pyrolysis of the two EMALs. FT-IR result show that both PKS-EMAL and WS-EMAL are Type HGS. Phenols, acids, few of alcohols, aldehydes and ketones are detected in volatile products from 500℃ pyrolysis of the two EMALs. Meanwhile, H-type, G-type and S-type phenols with proportions of 47.61%, 25.64% and 17.18% are obtained in phenolic products from PKS-EMAL pyrolysis; while they are 23.66%, 51.90% and 15.50%, respectively, in phenolic products of WS-EMAL. During 200-380℃, the main weight loss rate of PKS-EMAL pyrolysis is 50.80%/min, which is obviously lower than that (78.63%/min) of WS-EMAL. A shoulder peak of 27.40%/min at 265℃ is also observed in PKS-EMAL pyrolysis, which is closely related to release of H-derivatives during PKS-EMAL pyrolysis. The activation energy (127.92 kJ/mol) of PKS-EMAL pyrolysis at a conversion of 20% reduced by the exothermic effect corresponding torelease of H-derivatives, which was the main reason that the average activation energy (152.32 kJ/mol) of PKS-EMAL pyrolysis (20%-80%) was lower than that (161.75 kJ/mol) for WS-EMAL pyrolysis.
Abstract: The rape straw was taken as raw materials, and the HZSM-5 and MCM-41 catalysts were used and loaded into bed in two layers with different ways (HZSM-5/MCM-41 and MCM-41/HZSM-5) to explore the synergistic catalytic mechanism on the basis of bio-oil quality and catalyst durability. The physical and chemical characteristics of organic phase in purified bio-oil were analyzed, the compositions were analyzed by FT-IR and GC-MS, and the durability of catalysts was analyzed by TG. The results show that compared with the singular catalytic reaction, the liquid yield from synergistic catalytic reaction lowers somewhat and the gas yield increases. The physciochemical properties of organic phase in purified bio-oil increase and the organic phase obtained from MCM-41/HZSM-5 synergistic catalytic reaction has a relatively higher calorific value, 34.31 MJ/kg. The organic phase in refined bio-oil contains a variety of aromatic substances and a small amount of carbonyl substances, the synergistic catalytic reaction can produce more hydrocarbons and less oxygen-contained aromatic substances. The MCM-41/HZSM-5 synergistic catalytic reaction can produce higher levels of hydrocarbons in organic phase of refined bio-oil, which are mainly in single ring aromatics. There are two weight loss peaks for deactivated HZSM-5 molecular sieve and only one weight loss peak for deactivated MCM-41 molecular sieve in the range of 300-800℃, which show that the coke deposited on the MCM-41 catalyst has a single composition and is easy to remove and the synergistic catalytic reaction forms less coke.
Abstract: The depolymerization process of wheat straw alkali lignin in sub- and supercritical ethanol was investigated with a micro autoclave reactor. The degraded product properties and the depolymerization mechanism of lignin structure were studied by scanning electron microscopy (SEM), gas chromatography/mass spectrometry (GC/MS) and infrared spectroscopy (FT-IR). The experimental results show that the minimum residual char yield (16.5%) is obtained at the condition of ethanol supercritical point (240℃, 7.2 MPa). Under subcritical ethanol conditions, alkali lignin firstly melts and disperses in ethanol as 1.0-2.0 μm diameter of microspheres, then a small amount of ether linkages and benzene ring side chain Cα are broken to form phenols, esters, ketones and acids products. Under supercritical ethanol conditions, the diameter of molten microsphere is significantly reduced, and plenty of ether linkages and benzene ring side chain Cα are continuously broken, meanwhile, the lipid products are subjected to secondary decomposition reaction. The yield of lipid is decreased (11.94%), while the yield of phenolic products from depolymerization is increased (52.14%).
Abstract: NiP/SAPO-11 catalysts with various nickle loading amounts were prepared by the impregnation method, and their properties were determined by means of N2 adsorption-desorption, DRIFTS of adsorbed pyridine, NH3-TPD and H2-TPR. The catalytic hydrodeoxygenation of fatty acid methyl esters (FAME) and isomerization of consecutive paraffin products were carried out in a fixed-bed continuous-flow reactor. Liquid products were qualitatively and quantitatively identified by GC-MS and GC respectively. Under the operation conditions of 340℃, 2.0 MPa, WHSV of 2.5 h-1, H2 of 60 mL/min, the catalyst with 3% nickel loading (mass content) attained the high conversion of FAME (97.8%), C15-18 yield (84.5%) and isomerization rate (14.0%).
Abstract: Magnetic Fe3O4 was synthesized by chemical coprecipitation method, and used as a raw material for preparing Fe3O4/MgAl-LDH. The calcined Fe3O4/Mg(Al)O was taken as the catalyst for the transesterification of microalgae oil with methanol, and the biodiesel yield was used to evaluate the activity of the catalyst. Several instruments including TG-DTG, XRD, SEM, EDS, TEM, N2 absorption-desorption and VSM were employed to characterize the catalysts. The results show that MgAl-LDH and Mg(Al)O are successfully formed on Fe3O4 particles which have a strong magnetic response. When the reaction time is 4 h and the methanol/oil mol ratio is 13:1, the biodiesel oil yield reaches to 90%. After using for three times the catalyst still has certain activity and can be easily separated and recycled.
Abstract: Based on the reducing gases (H2 and CO) generated from biomass-based carbon at high clacination temperature, self-reducing bifunctional catalyst Ni-W/MOR was prepared by incipient impregnation. This series of catalysts were directly applied to cellulose hydrogenolysis to low carbon polyols in aqueous solution, omitting the catalysts reduction step. The effects of catalysts temperature of the catalyst and weight ratio of active components on conversion of cellulose and yield of target products were investigated. The optimal calcination temperature was 773 K through experimental results. XRD analysis showed that the crystallinity and species of metallic alloys were related to different weight ratios of nickel and tungsten. It was intuitively observed that the active metals showed good dispersion on the surface of MOR through TEM characterization, with particles sizes less than 20 nm. The total yield of low carbon polyols was up to 56.92%, including 52.30% of EG under the reaction condition of 5.0 MPa of H2 for 2 h reaction time and the calcination temperature of catalysts was 773 K.
Abstract: Metal-based ionic liquid [Amim]Cl/ZnCl2 was synthesized and its structure and acidity were characterized with FT-IR spectroscopy. The denitrogenation performance of the ionic liquid was investigated using Fushun shale diesel oil containing 0.52% basic nitrogen as feedstock. Experimental results showed that the ionic liquid exhibited good denitrogenation performance and 83.78% basic N-extraction efficiency was achieved under the optimized operation conditions, i.e., temperature of 30℃, 1:7 (mass ratio) IL:oil, reaction time of 20 min and settling time of 2 h. In addition, the basic N-removal efficiency of the ionic liquid can still remain 52% after four recycles.
Abstract: Three kinds of Cu-Zn-Al slurry catalysts were prepared respectively with copper citrate, copper nitrate and copper acetate as the source of copper by complete liquid-phase technology. The effects of different sources of copper on the catalytic performance of dimethyl ether synthesis from syngas were investigated. The catalysts were characterized by XRD, H2-TPR, NH3-TPD, BET, XPS and TEM. The results indicated that the texture morphology and catalytic performance of the catalysts varied significantly. The catalyst prepared with copper citrate showed the best dispersion of Cu species in the catalyst and the largest amount of reducable substance. Meanwhile, the Cu species have strongest interaction with other components. Copper citrate increased the ratio of the amount of weak acid and strong acid on the surface of catalysts, and also improved the performance of the catalyst for methanol dehydration. So the catalytic performance of the catalyst pre-pared with copper citrate was the best. The conversion of CO was 63.4% and the DME selectivity was 66.0%.
Abstract: A series of Co-APO-5 molecular sieves were prepared and used as the catalysts in the selective oxidation of cyclohexane; the effects of solvent and modification method on the catalytic performance of Co-APO-5 were investigated. The results illustrated that polar solvents containing π-bonds are favorable for the oxidation reaction and the conversion of cyclohexane increases with the increase of solvent polarity. The introduction of Si and F leads to a decrease of the tetrahedral cobalt content in the Co-APO-5 framework. However, introducing F can improve the crystallinity of Co-APO-5, whereas adding Si may promote the oxidation and reduction of cobalt species and then enhance the catalytic activity in oxidation. In general, the activity of Co-APO-5 catalysts is related to the content of tetrahedral cobalt in the framework, suggesting that the framework Co(Ⅱ) is probably the catalytically active species for the oxidation of cyclohexane.
Abstract: A series of CeO2 catalysts was modified with different acids including phosphotungstic acid (P-W), phosphate acid (P), partial ammonium tungstate (W), and phosphate acid plus partial ammonium tungstate (P+W); the effect of acid modification on the performance of CeO2 catalyst in the selective catalytic reduction of NO with ammonia (NH3-SCR) was then investigated. The results indicated that the CeO2 catalyst after acid modification possesses abundant surface acid sites of weak-medium strength and the acid quantity of various catalysts follows the order of P-W/CeO2 >W/CeO2 >P+W/CeO2 >P/CeO2. Due to the interaction between P and W species, the P-W/CeO2 catalyst modified with phosphotungstic acid exhibits high amount of weak-medium surface acid sites and active Ce and O species, which may promote the adsorption and activation of NH3 and then enhance its catalytic activity in the NH3-SCR of NO; over the P-W/CeO2 catalyst, the conversion of NO keeps above 90% at 225-450℃.
Abstract: All the membrane electrodes were prepared by ion beam sputtering (IBS) apparatus. Vacuum annealing in combination with acid etching was used as post-processing. The high resolution transmission electron microscopy and X-ray diffraction were employed to investigate the surface morphology and alloying degree of samples. The electrochemical performance was used to detect hydrogen evolution property. The result confirmed that, with the same condition of post-processing, the membrane electrode doped Ce had cross-bridged structure and higher alloying degree, and the electrochemical performance was enhanced by 92.25% compared to pure Pt.
Abstract: The fabrication of porous and stereoscopic anode is crucial for the effective use of dry methane as fuel in solid oxide fuel cells (SOFCs). In this work, tubular SDC coated with Ni0.5Cu0.5Ba0.05Ox (Ni0.5Cu0.5Ba0.05Ox/SDC) was prepared by hard template method combined with wet impregnation method. For comparison, Ni0.5Cu0.5Ba0.05Ox powder was also prepared by sol-gel method and then mixed with SDC to get anode Ni0.5Cu0.5Ba0.05Ox-SDC. Corresponding electrolyte-supported unit cells Ni0.5Cu0.5Ba0.05Ox/SDC|YSZ|LSM-YSZ and Ni0.5Cu0.5Ba0.05Ox-SDC|YSZ|LSM-YSZ were then fabricated for the power generation performance and long-term stability test. Fueled with dry methane at 800℃ on a fuel cell with Ni0.5Cu0.5Ba0.05Ox-SDC as anode, the maximum power density is only 324.99 mW/cm2 and the voltage drops 5.60% after 10 h operation; however, with Ni0.5Cu0.5Ba0.05Ox/SDC as the anode, the maximum power density reaches 384.54 mW/cm2 and no degradation in voltage is observed for 100 h. As reveled by SEM, the narrow pores in Ni0.5Cu0.5Ba0.05Ox-SDC anode are prone to block by carbon deposition; in contrast, Ni0.5Cu0.5Ba0.05Ox/SDC has a three-dimensional porous structure for the diffusion of fuel and reactant gas. The surface of SDC fiber tube is coated by the catalyst particles, which can improve the three phase boundary and enhance the cell stability.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
