Abstract: In order to study the effect of soluble organic matter within coal on its characteristics of gas adsorption, the organic matters in coal seam 7＃ (Linhuan) and coal seam 3＃ (Qinan) were extracted with THF at 30 ℃ under atmospheric pressure by microwave-assistant extraction. Adsorption isotherm experiments and low temperature nitrogen adsorption test were made for raw coal and their residues. The gas adsorbance, specific surface area and pore size distribution were analyzed. Gas adsorbance of soluble organic matter was theoretically calculated. The results show that CH4-adsorption capacity of raw coal is stronger than those of their residues. After extraction, the specific surface area and total pore volume increase and average pore size decreases. Meanwhile, methane adsorption capacity is mainly influenced by 1.7~5.0 nm pores. Methane adsorbances of soluble organic matter are 0.45~4.22 and 0.69~4.99 mL/g, which account for 30% and 38% of the maximum adsorption capacity of raw coal under 0.1~5.0 MPa. Soluble organic matter occupies part of pores of coal, which influences structure of pores in coal. At the same time, the methane can be dissolved and adsorbed in soluble organic matter of coal under pressure.
Abstract: The macromolecular structure model of Chengzhuang coal was constructed based on the results of proximate and ultimate analysis, 13C-NMR spectrum and XPS spectrum. In the model the numbers of rings in polycyclic aromatic hydrocarbon were distributed between 1 and 5. The aliphatic C atoms existed in the forms of -CH3,-CH2- and cycloalkanes. 9 atoms of O were in the form of C=O, while one in the form of -OH and another one in the form of -O-. 2 atoms of N were in pyrrole, while S atom did not appear in the model because its concentration was lower than 1%. Molecular mechanics (MM) and molecular dynamics (MD) was adopted to simulate the energy-minimum conformation of the model and the results showed that the aromatic layers tended to be parallel by intramolecular or intermolecular π-π interaction and the latter should be one of the main contributors for the short-range ordering of high-rank coal structure. The van der waals energy and hydrogen bond energy contributed to the energy-minimum conformation.
Abstract: The steam gasification behavior and kinetics of coal char fines derived from fluidized bed gasifier were investigated by TGS-2 thermogravimetric analyzer. Their physical and chemical properties were also compared with the corresponding coal chars and demineralized char fines. The results show that the gasification reactivity of char fines increase with increasing temperature. Compared with the coal char from pyrolysis, the char fine has a larger surface area and leads to a higher gasification reactivity. The reactivity of different coal char fines are also affected by their carbon crystalline structure and ash content. Based on this, the gasification reactions are described by the shrinking core model and the kinetic parameters are obtained, so as to provide some theoretical guides for the gasification of coal char fines.
Abstract: The isothermal gasification kinetics of coal char with CO2 was separately studied using a so-called micro-fluidized bed reaction analyzer (MFBRA) and a thermogravimetric analyzer (TGA). With minimized effects of heat and mass transfer, the reaction rate in MFBRA is much higher than that in TGA. And the maximal rate appears at a conversion of about 0.15 in MFBRA but at 0.45 in TGA. The shrinking core model can well describe the char gasification reaction both in MFBRA and in TGA. In the temperature range of 760~1 000 ℃, the char gasification reaction is investigated in two stages. At lower temperatures, the activation energy from MFBRA and TGA is very close, validating the reliability of MFBRA for gas-solid reaction kinetic studies. At higher temperatures, the estimated activation energy by MFBRA is obviously higher, showing a lower diffusion limitation in MFBRA. It is found that the measured frequency factor for the Arrhenius equation by MFBRA is much higher than that by TGA, complying with the higher reaction rate in MFBRA. As a consequence, MFBRA and TGA differ in diffusion and heating behavior, which can greatly affect the measurement of (apparent) kinetics.
Abstract: The temperature programmed steam gasification (TPSG) of lignite from Baganuur, Mongolia was studied in a micro fixed-bed reactor with chromatography. The formation rate of H2,CO and CO2 during the TPSG were examined using the lignite samples pretreated by washing with HCl and NH4OH solution or NaOH solution following the washing by HCl solution. All the samples were pyrolyzed at 650 ℃. The results show that a significant difference in the formation rate of gas components is presented for the tested lignite samples. The inherent minerals in the Baganuur lignite can accelerate the generation rate of H2 and CO2, but simultaneously reduce the generation rate of CO, which could manufacture a high H2/CO mol ratio syngas. Also, some inherent minerals in the Baganuur lignite can remarkably enhance the steam gasification rate, which results in an drop of initial steam gasification reaction temperature by over 100 ℃. It is speculated that the enhanced steam gasification reaction of Baganuur lignite could be attributed to the effect of some inherent minerals on the water-gas shift reaction. Finally, the possible in-situ catalytic mechanism of inherent minerals in Baganuur lignite to the steam gasification reaction is discussed.
Abstract: The rapid pyrolysis of the CWS and raw coal from Shenfu coalfield was carried out in a high-frequency furnace. The pyrolysis temperature ranged from 600 ℃ to 1 200 ℃ with an interval of 100 ℃. The effects of temperature on the yields of char and char-C were investigated. The structure of chars obtained were characterized by using XRD, N2 gas adsorption method and SEM; and the CO2 gasification reactivity of chars was examined using TGA (thermogravimetric analyzer). The results show that with the increasing of pyrolysis temperature, the yields of char and char-C for both CWS and raw coal decrease. When the pyrolysis temperature is lower than 900 ℃, the yields of char and char-C for CWS are nearly the same as that for raw coal, and when the pyrolysis temperature is higher than 900 ℃,the yields of char and char-C for CWS become much lower than those for raw coal. The degree of graphitization and the regularity of microcrystal structure of CWS chars are slightly higher than that of raw coal chars, and the specific surface area of CWS chars is also much higher than that of raw coal chars. The gasification reactivity of CWS chars is greater than that of raw coal chars.
Abstract: Combustion characteristics and thermal dynamic characteristics of inferior coal and core board mixture in O2 and N2 atmosphere were studied with O2 concentration of 20％, 30％, 50％, 70％, 90％ respectively. With the increase of O2 concentration, DTG curves tend to move to lower temperature region. Also, ignition temperature, maximum weight loss rate and its corresponding temperature, the temperature of burnout, and synthetic combustion factor of mixture, are compared. The results indicate that O2 concentration can significantly improve the combustion conditions. Apparent activation energy of the fixed carbon combustion section is put into the calculation and analysis, which shows that the apparent activation energy increases with the increasing O2 concentration. In order to quantize combustion condition internal and external, definition of combustion enhancement factor(C.E.F.) is put forward. In selected fixed carbon combustion segment, C.E.F. increases rapidly with the increase in O2 concentration, which proves the positive role of oxygen concentration on combustion. There are kinetic compensation effect between C.E.F. and apparent activation energy.
Abstract: Straw was mixed with 2 different coals including Neimeng lignite and Shenfu bituminous coal in different proportions of 0∶100, 20∶80, 40∶60, 60∶40, 80∶20, and 100∶0. The co-pyrolysis experiments of the blends were conducted in a fixed bed reactor. The co-pyrolysis characteristic of straw and coal blends and synergetic effects during co-pyrolysis were studied. The results show that the yield of co-pyrolysis of straw and coal blend based on volatile matters were higher than those of the sum of straw and coal individually. Meanwhile, considerable deviations from the average weighted value of gas yield were detected, especially for straw and Shenfu bituminous coal blend. The more straw was added into blend, the more gas yield produced during co-pyrolysis. However, straw addition did not play significant role in the char yield and organic functional groups characterization.
Abstract: The integrated process of aqueous phase reforming of methanol for hydrogen and hydrogenation of phenol and guaiacol, two lignin model compounds, was conducted with Raney Ni catalyst in this work. The effects of pressure, temperature, reaction time and mixture ratio of reactants on the performance of in-situ hydrogenation of lignin depolymerization model compounds were investigated. The mechanism was also discussed. Results showed that the guaiacol conversion and cyclohexanol selectivity reached 99.00% and 93.74% with time-on-stream of 7 h, while the phenol conversion and cyclohexanol selectivity were 90.50% and 99.29% with time-on-stream of 12 h under the optimal conditions of 220 ℃, initial pressure of 0 MPa(gauge pressure) and mole ratio of water/methanol/feedstock=20/5/0.8. The in-situ hydrogenation of phenolic compounds was also proved to be superior to the hydrogenation system of phenols with external hydrogen supply. This work provides a new alternative for production of chemicals from the depolymerization products of lignin.
Abstract: Comb-shaped polymer and reactive polymer are two kinds of polymers widely used in the tertiary recovery process at present and their viscosity and viscoelasticity are important indexes for evaluating the oil displacement efficiency. To investigate the effect of shear action on the properties of polymer solutions, the macroscopic and microcosmic properties of the comb-shaped polymer and reactive polymer, before and after shearing through the simulated hole cut, were compared. The results showed that at high-speed shearing and tensile stress, the viscosities of the comb-shaped polymer and the reactive polymer are decreased by 40.73% and 70.10%, respectively. With a shear frequency of 0.02 Hz, the interfacial dilatational elasticities of the comb-type polymer and the reactive polymer are reduced by 19.03% and 68.03%, respectively. Compared with the reactive polymer, the comb-shaped polymer still exhibits a loosen network structure and is present as aggregates dispersed in the solution after shearing, though its super-molecular structure is partially destroyed; the particle size of the comb-shaped polymer, as measured by DLS and AFM, is only slightly reduced. These suggest that the comb-shaped polymer has a superior shear performance to the reactive polymer.
Abstract: A series of solid acid SO42-/ZrO2-SiO2 catalysts with a fixed Zr/Si molar ratio of 1.1 were successfully synthesized in one-pot through changing the H2SO4/HCl volume ratio during the self-assembly process. X-ray diffraction (XRD), UV-visible DRS, and high resolution transmission electron microscopy (HRTEM) results demonstrate that all the resultant catalysts exhibit a highly ordered 2D hexagonal mesostructures with zirconia particles of homogenously distributed tetragonal nanocrystallites in mesoporous walls. N2 adsorption and pyridine in-situ Fourier-transformed infrared spectra (FT-IR) further reveal that the surface area, pore volume, pore diameter and the relative strength of Lewis and Brønsted acidic sites of resultant catalysts can be controlled by tuning the H2SO4/HCl volume ratio during the synthesis. Different from pure mesoporous SBA-15 material, the mesoporous SO42-/ZrO2-SiO2 materials prepared in this work exhibit high structural stability and catalytic activity in n-pentane isomerization, which is attributed not only to hydrochloric acid that facilitates the formation of mesoporous silica but also to sulfuric acid that helps to stabilize the structure of catalysts and produce acid sites. The methods proposed in this work provide an important approach to synthesize ordered solid acid catalysts with high stability and potential applications in various acidic-catalyzed reactions.
Abstract: Two kinds of Brønsted acid ionic liquids ([Hnmp]HSO4, [Hnmp]PTSA) were synthesized and characterized; their catalytic activity in the synthesis of poly(oxymethylene) dimethyl ethers (DMMn, n > 1) by the condensation of dimethoxy methane (DMM) and paraformaldehyde (PF) were also investigated. The results showed that the catalytic activity of ionic liquid was related to its acidity, [Hnmp]HSO4 has higher catalytic activity; the optimum reaction conditions were found as [Hnmp]HSO4 amount of 2.0%(mass fraction), feed mass ratio m(DMM)/m(PF) of 2.00, temperature 110℃ and reaction time 6 h, the conversion of DMM and selectivity to DMM3~8 reached 52.28% and 49.18%, respectively. The ionic liquid [Hnmp]HSO4 can be naturally separated from product phase and exhibits high stability upon reusage; it still remained highly active even after being reused for five times.
Abstract: The adsorption properties of CO2 on MCM-41 mesoporous materials impregnated with ethylenediamine (EDA), tetraethylenepentamine (TEPA) and two kinds of polyethylenimines (PEI600 and PEI1800), respectively, were studied with mass spectrometry (MS) and thermogravimetry (TG) techniques. The sample obtained by impregnating EDA (EDA-MCM-41) showed a low CO2 adsorption capacity due to the ready volatilization of EDA, while those samples prepared by TEPA (TEPA-MCM-41), PEI600 (PEI600-MCM-41) or PEI1800 (PEI1800-MCM-41) exbibit higher adsorption capacity and thermal stability although the adsorption capacity decreased with increasing molecular weight of amines. A maximum CO2 adsorption capacity of 2.7 mmol/g was achieved on the TEPA-MCM-41 with 40% TEPA. When this sample was regenerated at 100 ℃ under pure nitrogen atmosphere, its CO2 adsorption capacity was decreased by 7.4% after ten recycles in contrast to less than 1% for both PEI600-MCM-41 and PEI1800-MCM-41. However, when the regeneration atmosphere was changed to 80% CO2/20% N2, the regeneration temperature should be be increased to more than 160 ℃ for all the samples despite that PEI-MCM-41 showed high thermal stability than TEPA-MCM-41.
Abstract: The reaction mechanisms of SO2, NOx, CO2 with ammonia solution were described. And the liquid coexisting components related to the desorption of simulated decarburization solution, including (NH4)2SO3, (NH4)2SO4, NH4NO3, NaCl, NH4Cl and (NH4)2CO3, were analyzed. The results show that the desorption of CO2 is affected by the mass fraction of liquid phase coexistence components, pH of solution and surface tension. Most of liquid coexisting components could reduce CO2 desorption of decarburization solution. The restraining effect of liquid coexisting components with the mass fraction less than 10% in the decarburization absorbent liquid on CO2 desorption is as follows: (NH4)2SO3>NH4NO3>(NH4)2SO4 >NaCl>(NH4)2CO3. It is necessary to remove the impurities in flue gas before CO2 capture, because the purities are harmful for CO2 desorption due to the hazardous effects on the physical and chemical characteristics of decarburization solution.
Abstract: In order to study the characteristics of mercury emission and migration, EPA 30B method was used to determine the Hg concentrations in flue gases emitted from four typical pulverized coal-fired boilers in a large-scale power plant, and the Hg contents of related input／output materials in two of these boilers were also analyzed and compared. According to mass balance, the Hg distribution in different materials was obtained, and then the effect of major flue gas purification systems including selective catalytic reduction (SCR), electrostatic precipitation (ESP) and wet flue gas desulfurization (WFGD) on Hg emission was clarified. Based on these, the migration pattern of Hg in pulverized coal-fired boilers was summarized systematically. Experimental results indicated that Hg emissions of all the four boilers were below 3 μg／m3, which was much lower than the limit specified by the new Chinese national standard. The emission was even significantly lowered when SCR system was located upstream. The reason was in the fact that, when there was SCR system located, lots of Hg0 in flue gas could be catalyzed to Hg2+ and then adsorbed by fly ash. The solubility of Hg2+ was much higher than that of Hg0 in WFGD system, and the major Hg speciation in exhaust flue gas was Hg0. Most of the Hg absorbed in WFGD was transferred into desulfurization gypsum, while the enrichment in both desulfurization waste water and bottom ash was limited.
Abstract: The Ontario Hydro Method (OHM) was used to sample and analyze the mercury concentration in flue gas before and after ESP and WFGD in a 300 MW power plant. Mercury content in coal, bottom slag, fly ash of ESP, adsorbent (limestone) and desulfurization product (gypsum) was detected by DMA80. Mercury mass balance was calculated based on the online measurements through the boiler system. Factors affecting the distribution, transformation and removal of mercury in flue gas were discussed. The results show that the gaseous mercury (Hg0 and Hg2+) in flue gas accounts for about 95% of total mercury, while mercury in the bottom ash can be neglected. More than 95% of Hgp and a little gaseous phase mercury (Hg0 and Hg2+)were removed by ESP. The efficiencies to remove total mercury by ESP range from 12.77% to 17.38%. A removal efficiency for Hg2+(g) reaches up to 79.93%~90.53% by WFGD, however, the content of Hg0 after WFGD increases because part of oxidized mercury is reduced to elemental mercury during WFGD. The efficiencies to remove total mercury by WFGD range from 9.68% to 29.36%. ESP and WFGD can remove all of the Hgp and a majority of Hg2+ with a total mercury removal efficiency of 25.38%~38.38%. In general, the demercuration in the conventional devices of ESP and WFGD is not high, which perhaps is owing to the lower concentration of Cl in feed coal.
Abstract: Y2O3/Y, CeO2/Y and La2O3/Y samples were prepared by impregnation with Y zeolites as precursor. Removal of benzothiophene from octane was employed as probe reaction. The effects of loading amount of rare-earth metal oxide, adsorption temperature, adsorption time and ratio of adsorbent to oil on desulfurization have been investigated. The results showed that the optimum loading amount of the rare-earth metal oxide was 5%. More than 60% of benzothiophene was removed over the obtained samples at conditions of 50 ℃, 1 h and 1∶30 of adsorbent to oil ratio. Addition of toluene to the mixture of octane and benzothiophene depressed obviously the desulfurization capability of the samples. The rare-earth metal oxides were washed away during the desulfurization process. The loss amount of Y2O3 was the least, while CeO2 was the largest. The loss amount of CeO2 was 10 times larger than that of Y2O3.
Abstract: Iron-cerium mixed metal oxide (Fe0.95Ce0.05Oz) was prepared through co-precipitation method and used as the catalyst in the selective catalytic reduction of NO with NH3 (NH3-SCR); the effects of initial concentration of NO, molar ratio of NH3/NO and O2 concentration on its NH3-SCR activity were investigated in an integral reactor at steady-state and the kinetics were considered in a differential reactor. The results indicated that the amount of NO converted over per unit catalyst increases with the initial concentration of NO; with the increase of NH3/NO mol ratio, NO conversion is firstly increased sharply and then gradually reaches a stable value; O2 in the flue gas also plays an important role in the NH3-SCR reaction. The NH3-SCR reaction over Fe0.95Ce0.05Oz exhibits first-order with respect to NO, zero-order to NH3, and nearly 0.5-order to O2 at 175~275 ℃; the apparent activation energy is 42.6 kJ/mol.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
