Abstract: The effect of temperature (200~350 ℃) and pressure (0.25~8.00 MPa) on the elimination of main oxygen-containing functional groups of Shengli lignite was examined during pyrolysis in a fixed-bed reactor. Effects of the reduction of oxygen-containing functional groups on the moisture holding capacity (MHC) of coal samples were also investigated. The results showed that temperature was the key factor on the removal of carboxyl and phenolic hydroxyl from the lignite. The variation of pressure had few effects on the removal of carboxyl in coal; in contrast, phenolic hydroxyl was reduced to a minimum point at the pressure between 3.00 to 4.00 MPa. The carboxyl content in the lignite played a dominant role on the surface polarity and moisture holding capacity. The influence of specific surface area on the MHC became distinct when the carboxyl content in coal samples kept constant.
Abstract: Thermal extraction of Xianfeng lignite (XL) with 1-methylnaphthalene (1-MN) was carried out at 320 ℃, and the H2O2 oxidation of the thermal extraction residue (TR) was compared with that of XL raw coal. The thermal extract (TE), TR and the oxidized residues were characterized by element analysis and FT-IR. The aqueous products from oxidation reaction were esterified and analyzed by GC/MS. The result shows that the yield of TR from XL in 1-MN is 81.01%. It indicates that XL is mainly composed of macromolecular structure cross-linked by covalent bond, with less low molecular compounds associated by non-covalent bond interactions. The TE is mainly composed of aliphatic hydrocarbons, carboxylic acid esters with less aromatic structures and hydroxyl group. GC/MS results suggest that the water-soluble products contained highest content of α, ω-dicarboxylic acids, especially malonic acid and succinic acid, with much amount of benzoic acid and tricarboxylic acids. The low molecular weight compounds associated in the macromolecular structure of raw coal can be easily oxidized under the conditions and more species of oxidation products are obtained. Compared with the structure of raw coal, the structure of TR is more regular. The oxidation of TR mainly occurs on the macromolecular structure cross-linked by covalent bond, resulting in the higher yield of oxidized residue and less species of water-soluble products from TR. The high yields of malonic acid and succinic acid in the water-soluble products suggest that -CH2-and -CH2-CH2-are the main cross-linking bonds in the macromolecular network structure of XL.
Abstract: The solid state high resolution 13C CP/MAS NMR technology was employed to analyze O-containing functional groups in 4 coals. The variation and contents of inactive O-containing functional groups in the coals were obtained in combination with chemical method. The results show that the 13C CP/MAS NMR method is effective to obtain the contents of some O-containing functional groups. The contents of carboxyl and carbonyl in the low rank coal are from 0.00 to 1.41 and from 0.45 to 1.91 mol/kg, respectively. Combined with chemical method, the content of ether bond is obtained, which is from 5.33 to 10.54 mol/kg. However, the value of inactive ether bond in the coals is only from 0.04 to 0.13 mol/kg, and the occurrence of the ether bond is predominantly inactive, few of them exists in high rank coal.
Abstract: The continuous coal pyrolysis at 850 ℃ in a fluidized bed reactor under atmospheres containing O2, H2, CO, CH4, N2 and CO2 were carried out. The char product was characterized using Raman, BET and TGA (for evaluating reactivity). The results show that without O2 in the atmosphere, adding H2 and CO2 lowers the pyrolysis tar yield which is conversely higher with raising the CO and CH4 contents in the atmosphere. The introduction of O2 promotes the formation of CO and CO2, and thus the yields of tar and char decrease. The char yield increases with the addition of CH4 into the pure N2 atmosphere, which is ascribed to the cracking of CH4. PAHs content decreases with the addition of O2 into N2 atmosphere. CH4 promotes the production of alkyl-substituted naphthalenes and benzenes. CO inhibits the cracking of phenols to form benzenes. CO2 facilitates the formation of new micropores or opening of the closed pores, producing the chars with high surface area and the corresponding highest oxidation reactivity. The carbon deposition via CO disproportionation and CH4 cracking in the presence of CO/CH4 blocks some pores and thus lowers the surface area and reactivity of the char. The char produced with the inclusion of H2 and CH4 results in a more condensed crystallite structure via hydrogen radicals penetration and thus lowers the oxidation reactivity.
Abstract: In this work, the slurryability of direct coal liquefaction residue (DCLR) was systematically studied, and the effects of particle size distribution (PSD), stirring time, dosage and types of dispersant on the quality of direct coal liquefaction residue-water slurries (DCLRWS) was investigated. The results show that the dispersancy of naphthalenesulfonate formaldehyde (NSF) is much better than that of sodium lignosulfonate (SL), while the rheology of DCLRWS dispersed by NSF is poorer, which is mainly related to chemical characteristics of SL and NSF and interaction between dispersant with particles. Based on the experiments, the optimum conditions for preparing DCLRWS are determined, as follows: particle size distribution of Alfred model (d280~154 μm, 14%, d154~74 μm, 16%, d<74 μm, 70%), stirring strength, 3 000 r/min; stirring time, 20 min; the dosage of NSF, 1.0%. Under the optimal experimental condition, the maximum concentration of DCLRWS is up to 73.5% and 71.0% by using the NSF and SL as dispersant, respectively.
Abstract: Two pulverized coals with different slagging tendencies were combusted in a pulverized coal boiler in which three kinds of refractory plates were arranged uniformly. After combustion, the slagging behavior of coal ash on the refractory plates was observed. In order to examine the degree of corrosion by fly ash, the cross-sectional of refractory plates were investigated by energy spectrum analysis. The results show that with the rise of temperature in the furnace, the slagging degree on the surface of refractory plates and the corrosion degree increase. When the temperature in the furnace is higher than the melting temperature of fly ash, the slagging degree on the surface of refractory plates increases sharply. In industrial boilers, the surface temperature of refractory plates lower than the fly ash melting temperature can effectively reduce the possibility of surface slagging. In addition, compared with the jade texture refractory plates, the silicon carbide refractory plate has superior anti-slagging properties.
Abstract: The fly ashes from a 320 MW unit boiler with three excess air conditions were sieved to 4 sizes. The carbon contents of the ashes were measured, and the ashes were heated at two heating modes. The Hg contents of the ashes were analyzed using LUMEX Mercury Analyzer, and the Hg species in the ashes was determined according to the Hg release characteristics at different heating temperatures. The activation energies for Hg release were calculated. The results indicate that the Hg concentration in the ashes increases with the decreasing of ash size. Increasing the excess air leads to the decrease of carbon in ash, while the influence of excess air on the Hg content varies with ash size. Hg compounds in fly ash are mainly HgCl2 and HgS. The rising excess air results in a decrease of HgCl2 proportion and an increase of HgS proportion, while the proportion of HgO and HgSO4 keeps almost constant. Residence time is a key factor to influence the formation of particulate Hg. The increasing of excess air and particle size leads to an increase of activation energy for Hg release.
Abstract: Rice stalk (RS) was liquefied in ethanol under sub-and supercritical conditions in a batch autoclave; the influences of reaction temperature, RS/ethanol ratio and residence time on the liquefaction behavior were investigated. Under the optimized conditions, i.e. 325 ℃, a RS/ethanol ratio of 1/10 (g/mL), and a residence time of 60 min, the RS conversion and oil yield reach 78.32% and 55.03%, respectively. The GC/MS analysis results illustrate that the dominant components of the bio-oil are phenols and esters, which account for about 50% of the bio-oil product. The bio-oil product obtained exhibits a high heat value (HHV) of 28.95 MJ/kg, a kinematic viscosity of 5.63 mm2/s, and a water content of 2.2%.
Abstract: Coal-based solid acids (CSAs) were successfully prepared from coals with different ranks at various carbonization temperatures. XRD, FT-IR and 13C NMR were employed to characterize structure of the catalysts. The influence of coal rank and carbonization temperature on the heterogeneous catalytic hydrolysis of cellulose was investigated by comparing the yield of reducing sugar and glucose. The results show that coal has a structure advantage over the other traditional carbon sources for solid acids. In contrast to the traditional carbon-based catalysts, the unit structure of CSA is fused aromatic rings linked by bridge bonds (-O-, -CH2-) and the fused aromatic rings are bearing side chains (-CH3, -OCH3, -CH2CH3) besides phenolic -OH, -COOH and -SO3H groups. In addition to the sulfonic groups, the others are derived from the raw coal structure. With rising carbonization temperature, the species and amounts of functional groups and the density of sulfonic acid groups are found to decrease gradually in CSAs, while the aromaticity of CSAs is opposite. The adjustability of CSAs structure and required carbonization temperatures are reduced with increasing coal rank. The CSAs show a higher activity in the cellulose hydrolysis process, wherein the Huolinhe CSA has the highest catalytic activity. The hydrolytic activity is influenced by the size and the stack height of the aromatic sheet, the bridge bond and the sulfonic acid group density, which is a result of the synergistic effect of a number of reactive groups.
Abstract: Delafossite CuCrO2 was prepared with Cr(NO3)3 and Cu(NO3)2 by the semi-wet method via two different routes. The samples were characterized with thermogravimetry-differential scanning calorimetry, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy techniques. It was shown that addition of Cr(OH)3 precipitated with aqueous ammonia solution into aqueous Cu(NO3)2 solution is a suitable route to synthesize CuCrO2. In the calcination process, the precursor transformed into CuCrO2 in the sequence: Cr(OH)3 → CuCrO4 → CuCr2O4 → CuCrO2, as verified by the TG-DSC and XRD results. The composites of CuCrO2-WO3 and CuCrO2-ZnO prepared by the grinding method show higher activity than CuCrO2 in the photocatalytic splitting of water into hydrogen under the irradiation of a high-pressure mercury lamp or a xenon lamp.
Abstract: Alumina supports were synthesized by hydrochloric acid reflux and ammonia precipitation methods; after that the Pt-Sn-K/γ-Al2O3 catalysts were prepared by complex impregnation method under vacuum with alumina of different sources as the supports. The catalysts were characterized by N2 physisorption, CO pulse chemisorption, H2 temperature-programmed reduction, NH3 temperature-programmed desorption and thermogravimetric analysis; the effect of the alumina support on the performance of Pt-Sn-K/γ-Al2O3 catalysts in the dehydrogenation of isobutane was investigated. Compared with the catalyst supported on Al2O3 from hydrochloric acid reflux, the catalyst supported on the Al2O3 from ammonia precipitation is provided with smaller platinum particle size and weaker acidic distribution, and then exhibits higher activity and selectivity to isobutene in isobutane dehydrogenation. Moreover, the catalyst with Al2O3 synthesized by ammonia precipitation as the support exhibits better resistance against coke deposition and the coke deposited also has a lower degree of graphitization, which endues the catalyst with better stability. During a long term test of 14 d over the catalyst with Al2O3 synthesized by ammonia precipitation as the support, the conversion of isobutane is initially 56.67% and then decreased to 34.71% after 14 d; meanwhile, the initial selectivity to isobutene is 80% and it remains approximate 94% after 7 d.
Abstract: The catalyst samples with different Fe, Mn and K proportions were prepared by the typical method.The catalyst were characterized by X-ray diffraction(XRD), N2-adsorption, Raman, scanning electron microscope (SEM) and their performance for CO hydrogenation to light olefins was investigated. The results showed that the incorporation of Mn with appropriate contents can improve the dispersion of the active phase and suppress the carbon chain growth. The interaction of Fe-Mn can not effectively increase olefin/paraffin ratio. Active iron species precursor(α-Fe2O3) are more advantageous to olefin formation reaction. Mn oxides are restrained by the addition of K, giving rise to more crystal defects of FeMn compound. As a result, a higher yield of light olefins is acquired for Fe-Mn-K than Fe-Mn and Fe-K catalytic system.
Abstract: The stop-effect phenomenon on the catalytic dehydration of ethanol over HZSM-5 zeolite was observed. That is, when stopping ethanol-water feed for a period of time and restoring the feed, a dramatic increase on ethylene selectivity could be found. At different reaction conditions, it was found that the stop-effect was enhanced by increasing the stop time and reaction temperature or decreasing the feed speed. When the ethanol concentration was kept at 55%, the stop-effect could be strengthened and the high ethylene selectivity was maintained at long time. 500 h catalyst stability test showed that the stop-effect can improve the life span of the catalyst effectively. By studying the aqueous ethanol dehydration mechanism and experimental results, the preliminary conclusion is that causes of the stop-effect on the catalytic dehydration of ethanol over HZSM-5 is the accumulation of ethoxy intermediate and regeneration of empty catalytic active sites in stop operation.
Abstract: SBA-15 molecular sieves were modified with Al by adjusting pH value and post-grafting synthesis and used as the catalysts for hydrocracking. The new mesoporous materials were characterized by XRD, 27Al NMR, N2 adsorption and desorption and NH3-TPD. The results showed that Al-SBA-15 is successfully obtained through synthesis via adjusting pH value; it exhibits an ordered hexagonal mesoporous structure and well hydrothermal stability. Al modification is able to enhance the amount of surface acid sites of SBA-15, which induces the Al-SBA-15 catalyst with high selectivity to middle distillate for hydrocracking.
Abstract: The solid alkaline catalysts of supported potassium halides were prepared by impregnation method and used in the methanolysis of phenyl urea with methanol to synthesize methyl N-phenyl carbamate (MPC); the influence of oxide supports and potassium halides on the catalyst performance was investigated. The results indicated that KF/Al2O3 exhibits high catalytic activity and selectivity to MPC; the KF/Al2O3 catalyst containing 50% KF and calcined at 500 ℃ for 4 h performs best in the methanolysis of phenyl urea, over which the conversion of phenyl urea and selectivity to MPC reach 96.5% and 86.3%, respectively. The XRD results proved that KF and Al2O3 are partially transformed to K3AlF6 due to the strong interaction between KF and Al2O3. Both KF and K3AlF6 are active for the activation of methanol and selective conversion of phenyl urea; the excellent performance of KF/Al2O3 catalyst in the methanolysis of phenyl urea to MPC can be ascribed to the synergy of KF and K3AlF6.
Abstract: Fe2O3/LaFeO3 was prepared by citric acid complexation method and used as oxygen carrier in chemical-looping hydrogen generation; the effect of Fe2O3/CH4 ratio, stream amount and metal loading on the performance of Fe2O3/LaFeO3 as oxygen carrier at 900 ℃ and atmospheric pressure were investigated. The results showed that the oxygen carrier performs best with CH4 conversion of 60% and single-loop H2 output of 45 mL, when the ratio of Fe2O3/CH4, stream input and Fe loading are 2, 0.1 mL, 15%, respectively. The XRD and H2-TPR results suggest that the active site is the adsorbed oxygen rather than metal oxide; the easier for the reduction of the adsorbed oxygen, the higher are the conversion of CH4 and the output of H2. Moreover, the oxygen carrier is still in perovskite structure and CH4 conversion and H2 output remain stable even after 60 cycles.
Abstract: Five imidazolium-based ionic liquids were used as the electrolytes and their effects on the performance of fuel cell were investigated in a free electrolyte fuel cell. The results indicated that with H2 as fuel, the cell potential and the power density at the same current density decrease following the sequence of [Bmim]BF4 > [Bmim]PF6 > NaOH >> [Bmim]Cl > [Bmim]Br > [Bmim]HSO4; on the contrary, when methane is used as fuel, the cell potential and the power density decrease following the sequence of [Bmim]Br > [Bmim]HSO4 > [Bmim]Cl > NaOH > [Bmim]BF4 > [Bmim]PF6. When [Bmim]BF4 is used as the electrolyte of H2 fuel cell, both of the cell potential and the power density decrease with the increase of temperature and water content in the ionic liquid.
Abstract: A series of Cu-V-O oxide catalysts with different Cu-V molar ratios were prepared by the sol-gel method. The catalysts were characterized by means of XRD, BET and H2-TPR. The catalytic activity and sulfur resistance for toluene combustion were tested. The results indicated that Cu3V2O8 crystal structure was formed in the catalyst, which improved the lattice oxygen in the structure of Cu-doped catalysts and increased the surface area, leading to better re-dox-ability of the catalysts. The Cu0.15V0.85 catalyst showed the best activity and sulfur resistance. The loading of TiO2 can significantly improve the catalytic combustion activity and sulfur resistance of the mixed oxide catalysts.
Abstract: The volatility and the stabilization of heavy metals in fly ash in municipality & agriculture mixed waste incineration(Type A) and municipal solid waste incineration(Type B) were investigated. And the heavy metals stabilization mechanism was studied by using FT-IR and XRD. The results indicate that the volatility of heavy metals is higher in type B than that in type A, and is significantly affected by the content of chloride in waste source. The volatility of heavy metals in fly ash varies in a sequence of Mn, Cr < Zn, Cu < Pb, Cd. More than 50% of Pb and Cd are volatilized when the temperature exceeds 1 000 ℃. The relatively optimal thermal treatment temperature is 800 ℃and the heavy metals stabilization is higher and the evaporation rate is lower. The primary mechanism of heavy metals stabilization is the formation of stable silicate structure system above 800 ℃.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
