Abstract: Shengli lignite has been acid-washed. The chemical composition of ash from the raw sample was determined by X-ray Fluorescence (XRF). The acid-washed lignite was subsequently exchanged with different concentrations of Ca(CH2COOH)2 solution. Ion-exchange process was characterized by FT-IR, the ash content and pH value. The re-adsorption water contents of treated and raw samples were determined across a range of relative vapor pressures. The extend of ion-exchange reaction between Ca(CH3COO)2 and -COOH groups was controlled by the concentration of Ca(CH2COOH)2 solution. The effects of Ca2+ on equilibrium re-adsorption water values varied depending on relative vapor pressures and the amount of loaded Ca2+. Furthermore, the factor that controls equilibrium re-adsorption water content at relative vapor pressure of 92% or less is capillary force between Ca2+-carboxyl group complex and capillary. However, at higher relative vapor pressure the key factor becomes interactions of free water molecules.
Abstract: ICP-MS was used to examine the rare earth element (REE) in the raw coals from Yimin coalfield, East Inner Mongolia, and the samples were treated by acid washing and humic acid extraction. Based on the correlation between the REE concentration and the ash and organic elements(C, H, O) for raw coal and demineralized coal as well as the occurrence of REE in humic acids, it can be concluded that the interaction between REE and the organic matter should be controlled by deoxygenation, dehydrogenation and carburetion during the coalification. Four kinds of REE-organic compounds in these coals might be formed: (1) the REE-organic complexes with aromatic structures highly substituted by aliphatic side chains, (2) ones with hydroaromatic structures, (3) ones with lower substituted aromatic structures, (4) ones with oxygen-containing functional groups. The REE-organic compounds with lower substituted aromatic structures and oxygen-containing functional groups are less stable. Meanwhile, not only the lanthanide contraction effect but also the valences of REE can influence the stability of REE-organic compounds. Compared to the LREE(light rare-earth element), the HREE(Heavy rare-earth element)-organic complexes are more stable. The combination of LREE with humic acid is unstable contrary to the lanthanide contraction in raw coal. Like the combination of MREE(middle rare-earth element) and HREE with humic acids in raw and demineralized coals, however, the combination of LREE with humic acids in demineralized coal shows a good lanthanide contraction effect.
Abstract: A comparison of coal tar catalytic cracking over hot char from in-situ coal pyrolysis and cooling char was investigated. The results show that the in-situ char has a higher capability of removing tar than the cooling char under the same reaction conditions. The tar content in the product gas is reduced to as low as 100 mg/m3 when the temperature of the in-situ char bed and the gas residence time in the bed are 1 100 ℃ and 1.2 s, respectively. BET analysis shows that the in-situ char has larger specific surface area and more micro pores than the cooling char, while the uniformity of the carbon crystallite structure in the cooling char increases, causing the decrease of the char's catalytic activity for tar removal. With the increase of gas residence time in the char bed or of cracking temperature, the tar content in the product gas decreases greatly, while the difference of catalytic activity for tar cracking between in-situ char and cooling char also decreases. The activity of the spent char is decreased significantly. However, the activity of the spent char can be basically recovered when it is partially gasified with steam.
Abstract: Some hazardous trace elements in coal, bottom ash, fly ash and fine fly ash from a circulating fluidized bed (CFB) boiler in a power plant were examined. The distribution, enrichment and partitioning behavior of Be, Zn, Hg, V, Cr, Mn, Co, Ni, Cu, As, Se, Cd and Pb were analyzed. The results show that the distribution and enrichment characteristics of trace elements are greatly affected by the temperature of CFB. According to the relative enrichment factor (ER), Be, V, Co and Se trend toward fly ash; Zn and Mn show a tendency into bottom ash. Some volatile trace elements like Cd,Pb,Ni and Cu show low enrichment in both bottom ash and fly ash. The element of As is affected by calcium oxide, and its volatility is not obvious. Hg is more likely discharged with flue gas. Hg, As, Se, V, Cr, Mn, Co, Ni, Cu, Zn and Pb all have an enrichment tendency toward fine particles. On the basis of ER and behaviors of the 13 trace elements in CFB boiler, these elements are divided into 3 categories: A(ER<0.1), Hg mainly volatilizes into the atmosphere; B(0.1<ER≤0.85), As, Be, Ni, Cu, Se, Cd, Pb, Co and V are more easily volatilization; C(ER>0.85), Zn, Mn and Cr mostly stay in solid residues.
Abstract: A Cu-based oxygen carrier Cu80Si950 was prepared by mechanical mixing, and the chemical looping combustion (CLC) of graphite, combustible solid waste(CSW) and model compound CH4 with Cu80Si950 oxygen carrier was studied in a two-stage tubular furnace reaction platform and a thermo-gravimetric analyzer (TGA), respectively. The experimental results prove that the Cu80Si950 oxygen carrier has a high mechanical strength, excellent reaction and recycle stability, which makes it a promising oxygen carrier for CLC process of CSW. Scanning electron microscope (SEM), X-ray diffraction (XRD) and strength analyzer have been used to characterize the oxygen carrier of each reaction stages. The results show that the morphology of Cu80Si950 oxygen carrier changes and the crushing strength dereases dramatically after CLC process. However, the Cu80Si950 oxygen carrier after experiencing several loops displays a trend of structural regularization with porous structure on the surface, which keeps the oxygen carrier a constant crushing strength and a greater durability.
Abstract: Hydrogen donor visbreaking and conventional visbreaking of Venezuelan vacuum residue were studied at 425 ℃ for different reaction time in an autoclave. Changes of average molecular weight, elemental analysis, hydrogen type distribution and average structural parameter of the asphaltenes separated from the feed residues of the two processes and their visbroken residuals were investigated. The results showed that in comparison with conventional visbreaking at the same reaction time, average molecular weight and S/C atomic ratio of hydrogen donor visbroken residuals were lower, however, the H/C atomic ratio and total active hydrogen were higher. The hydrogen donor could reduce the aromatic carbon rate of asphaltenes and increase the naphthenic carbon rate and the ratio of naphthenic ring number to aromatic ring number so as to delay the phase separation and coke formation.
Abstract: Low-temperature fast pyrolysis of fructose offered a promising way to produce 5-hydroxymethyl furfural (HMF) together with furfural (FF) as an important by-product. In this work, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) measurements were performed to investigate the product distribution from fast pyrolysis of fructose; the effects of pyrolysis temperature on the HMF formation behaviors were considered. The results indicated that HMF is the predominant product from the fast pyrolysis of fructose; the product mixture with highest content of HMF (81.2%, determined by the gas chromatography peak areas) is obtained at 250 ℃, while the maximal yield of HMF is achieved at 350 ℃. Five possible pathways of HMF formation from fructose were considered by density functional theory (DFT). The DFT calculation results suggested that pathway 1 is most energetically favored, i.e. fructose molecule first undergoes a dehydration process by losing -OH at C2 and -H at C1 and then it is subjected to subsequent dehydrations involving -OH at C3 and -H of hydroxyl group at C1 as well as -OH at C4 and -H at C5, to form HMF.
Abstract: Dimethyl ether (DME) is amongst one of the most promising alternative, renewable and clean fuels being considered as a future energy carrier. In this study, the comparative catalytic performance of the halogenated γ-Al2O3 prepared from two halogen precursors (ammonium chloride and ammonium fluoride) is presented. The impact of ultrasonic irradiation was evaluated in order to optimize both the halogen precursor for the production of DME from methanol in a fixed bed reactor. The catalysts were characterized by SEM, XRD, BET and NH3-TPD. Under reaction conditions where the temperature ranged from 200 to 400 ℃ with a WHSV =15.9 h-1 was found that the halogenated catalysts showed higher activity at all reaction temperatures. However, the halogenated alumina catalysts prepared under the effect of ultrasonic irradiation showed higher performance of γ-Al2O3 for DME formation. The chlorinated γ-Al2O3 catalysts showed a higher activity and selectivity for DME production than fluorinated versions.
Abstract: γ-alumina supported Ni-W catalysts with different zeolite Y contents were prepared and characterized by N2 sorption, XRD, H2-TPR and NH3-TPD. Their catalytic activities were investigated on a trickle bed reactor by hydroprocessing cresol-naphthalene model compounds in n-heptane solution. The results show that all the catalysts exhibit excellent hydrodeoxygenation and hydrogenation activities, while the isomerization and ring-opening products increase with the addition of zeolite, and trans-decalin is preferred with acid sites. A better catalyst was selected for hydroprocessing a low temperature coal tar fraction and the product oil was analyzed by GC-MS and elementary analysis. Phenols and di-aromatics in the tar are almost converted into indans, cycloalkanes and hydro-aromatics. In the meantime, heteroatoms, especially S and O atoms, reduce remarkably.
Abstract: The effect of operation parameters, such as particle size of the CeY sorbent, space velocity, and concentration of the solution and temperature of the fixed bed, on the adsorption of thiophene from benzene was investigated. The results show that this effect can be ascribed to the change of the inner and external diffusion process of the mass transfer resistance and the adsorption type, which are affected by those operation parameters respectively. The suitable operation parameters were the particle sizes of 0.2~0.3 mm, space velocity of the solution of 0.85 h-1. At the conditions of room temperature and atmospheric pressure, CeY sorbent can entirely remove the thiophene from benzene with the breakthrough time and adsorption capacity of thiophene of above 400 min and 4.61 mg/g in the benzene containing thiophene 500 mg/L, respectively.
Abstract: Cu model catalyst was prepared through thermal decomposition method and ZrO2/Cu was obtained through impregnation method. The morphology and surface composition of the catalysts were investigated using SEM and XPS. Surface specie changes over Cu and ZrO2/Cu in the process of the reduction were investigated using in-situ Raman. In the mean time, CO and H2O were passed through in sequence, and the Raman spectra were recorded. The results show that surface of Cu mainly consists of CuO species while that of ZrO2/Cu contains rich surface hydroxyl groups besides CuO species. ZrO2/Cu is easier to be reduced to CuO with ZrO2 species agglomerating to floccus state. However, Cu2O formed over Cu catalysts after reduction. CO adsorption over Cu produces Cu-CO with the disappearance of Cu2O and production of CO2. Water is weakly adsorbed over Cu but is adsorbed strongly over ZrO2/Cu to produce Cu2O species via Cu-OH intermediate.
Abstract: With the simulated solar reaction system irradiated by Xenon lamp, an experiment of hydrogen making from steam-carbon reaction catalyzed by K2CO3 was carried out at about 700 ℃. It is found that the rate of hydrogen production with catalysts is 10 times more than that without catalysts, and there is no obvious difference in the rate of hydrogen production with the catalyst content from 10% to 20%. The oxygen-transfer mechanism for hydrogen making from steam-carbon reaction catalyzed by K2CO3 was discussed in detail, which was used to explain the unbalanced phenomenon of hydrogen and oxygen in reaction product. The efficiency of light energy conversion to chemical energy reaches to 13.12% in the experiment, which is better than that of photovoltaic method(10.85%). Some approaches for improving the energy conversion efficiency were proposed.
Abstract: Pt/Au/Fe3O4 nanocomposites were prepared by the continuous reduction method, through loading Pt and Au on the surface of nano Fe3O4. The Pt/Au/Fe3O4 nanocomposites were characterized by UV-vis spectra, transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS); their electrocatalytic activities in methanol oxidation were investigated. The results indicated that Au and Pt are uniformly deposited on Fe3O4 surface. The cyclic voltammograms of Pt/Au/Fe3O4 suggests that the best catalytic performance is achieved when the amount of H2PtCl6 added is 8 mL. Current peak ip is proportional to the square root of scanning speed (v1/2) and the catalytic methanol oxidation process is under the control of diffusion. The Pt/Au/Fe3O4 nanocomposites remain high active during the measurements of cyclic voltammograms for 201 times, suggesting that Pt/Au/Fe3O4 is a kind of anode catalyst materials with high chemical activity and stability.
Abstract: Monolithic catalysts for catalytic combustion of dimethyl ether (DME) were prepared by a dip-coating method using Al2O3/cordierite as support and manganese oxide octahedral molecular sieve (OMS-2) as active component. The effect of different types of organic polymer binder and the coating times of active component on the performance of DME combustion were investigated. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), hydrogen temperature-programmed reduction (H2-TPR) and oxygen temperature-programmed desorption (O2-TPD) techniques. The results showed that the best catalyst was the one using methoxy polyethylene glycol (MPEG) as the coating binder by one-time coating. The active component OMS-2 was in a cluster form and homogeneously dispersed on the surface of the support because of the strong interaction between OMS-2 and Al2O3 coating. The Al2O3 coating could significantly improve the surface area of catalysts, and thus enhance the activity performance. The highest catalytic activity for DME combustion with a complete combustion temperature (t90) of 257 ℃ was obtained.
Abstract: A series of amine modified SBA-15 was prepared by a twice grafting method for CO2 capture. The resulted materials were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, thermogravimetry (TG), elemental analysis, transmission electron microscopy (TEM) and Flourier transform infrared (FT-IR) spectrometry. CO2 adsorption capacity of the adsorbents was obtained in a fixed bed through a breakthrough curve method. Effects of different preparation methods and different types of grafted organic amines were studied and recycled adsorption/desorption testing was carried out to evaluate the stability of the adsorbents. The results showed that, polyethylenimine(PEI) grafted SBA-15 prepared by supersonic method showed the best adsorption capacity, the optimist result was 1.72 mmol/g at 25 ℃ and 10 kPa CO2 partial pressure. Furthermore, its adsorption capacity was found to be remaining constant after multiple adsorption/desorption cycles, indicating the high thermal stability of this adsorbent.
Abstract: NO reduction by methane over iron oxides( fully oxidized iron mesh roll)was experimentally investigated in an one-dimensional electrically heated temperature programmed ceramic tubular reactor at 300~1 050 ℃ in N2 atmosphere. The NO reduction efficiency, CO formation, the components variation and microstructures of the iron sample after reaction were measured. The reaction mechanism of NO reduction by methane over iron oxides was proposed. A durable NO reduction by methane over iron oxides in simulated flue gas was conducted at 1 000 ℃. Results showed that methane was very effective to reduce NO over iron oxides. In N2 atmosphere, 100% NO reduction efficiency was achieved when temperature was above 850 ℃. In simulated flue gas, very good durable performance was demonstrated. 1.17% vol. methane could reduce 100% NO over 100 h at 1 000 ℃ in simulated flue gas which contained 2.0% O2, 16.8% CO2 and 524×10-6 NO in N2 base. Research results on the mechanism showed that NO was reduced with methane via two major routes: one is by reburning while the other is methane reduced iron oxides to metallic iron through redox reactions and then NO was reduced by metallic iron. The latter mechanism was believed to play the major role of NO reduction.
Abstract: The geometry optimizations and vibrational frequencies of reactions, products and transition states involved in pyrolysis of n-decane were performed using the hybrid method B3LYP with 6-311G (d,p) basis set based on density functional theory. The potential energy surfaces of n-decane were built by the B3LYP/aug-cc-pVTZ methods. The rate constants of all reactions with Eckart correction were calculated by the TheRate program package. The heat capacity and entropy (Cp,mθ and S298 Kθ) at different temperatures were obtained by statistic thermodynamics. In order to calculate the standard formation enthalpy (△fH298 Kθ) for all species, isodesmic reactions were designed. The Chemkin II program was used to model the product distribution and heat sink. The effects of the temperature and pressure on the heat sink and product distribution were discussed. The results show that the C-C bond breaking process is the initial step of all reactions and H-abstraction reaction is easier to proceed than the β-scission reaction. The cracking initial temperature is 500 ℃ and the reactions mainly occur in the range of 600~700 ℃. The major products are hydrogen, methane, ethylene, ethane, propylene and 1,3-butadiene and the product distributions vary with temperatures. The total heat sink of n-decane is 2.334 MJ/kg at 600 ℃ and 2.5 MPa, with the conversions of 25.9%, which could meet the cooling requirement of aircrafts at 5~6 Mach number.
Abstract: Immobilized ZnCl2 (Silzic) catalyst was prepared and used in the synthesis of 3-methyl-3-buten-1-ol (MBOH) from isobutylene and formaldehyde; the effects of the reaction parameters, such as temperature, molar ratio of isobutene to formaldehyde, reaction time and catalyst content on the reaction behavior were investigated. The results showed that the conversion of formaldehyde is over 99% under various conditions. The reaction temperature as well as the catalyst acidity and the amount of the acid sites are dominant factors in influencing the selectivity to MBOH. Under the optimum reaction conditions, i.e. 210 ℃, 8 g 1,4-dioxane, 1.5 g polyoxymethylene, n(isobutylene)/n(polyoxymethylene) ratio of 7, 30 mg Silzic (1 mmol/g), and reaction time of 2 h, the selectivity and yield of MBOH reach 93.8% and 93.4%, respectively. The Silzic catalyst exhibits certain reusability; the yield of MBOH remains 85.2% after reusing the catalyst for 5 times.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
