Abstract: Concentration, distribution and modes of occurrence of 15 harmful trace elements including As, Pb, Hg, Se, Cd, Cr, Co, Mo, Mn, Ni, U, Th, Be, Sb, and Br in No.2-2 coal seam, Majiata strip mine were studied. Compared with the average concentrations of trace elements in Chinese coals, the coal in No.2-2 coal seam of the Majiata strip mine contains higher concentration of Hg and Mn. They may be harmful to the environment in the process of combustion and in other utilization. The distribution characteristics of the trace elements and pyrite sulfur in vertical section indicate that the distributions of the most trace elements in the coal seam are heterogeneous. The concentrations of As, Pb, Cr, Ni, Co, U, Mo, Be and Sb are higher in top or bottom and lower in coal seam, whereas the concentration of Br is higher in coal seam and lower in top and bottom. Cluster analysis of trace elements, pyrite sulfur, and major elements, such as Al, Fe, Ca shows that pyrite sulfur, As and Pb are closely associated and reflect the influence of pyrite. U, Cr, Th, Mo, Be, Sb, and Mn are related to clay mineral, which is the main source of ash. Br and Hg may be controlled by organic matter.
Abstract: Reducibility of coal, like rank and maceral, is one of the main factors influencing the properties of coals. The effect of coal reducibility on structural characteristics of macerals is the basic approach for understanding the difference of coal properties from the molecular viewpoint. XPS（Xray Photoelectron Spectroscopy）analysis was carried out to determine the forms and difference of carbon, oxygen, nitrogen, sulfur on the surface of vitrinite and inertinite from Pingshuo and Shendong coals with similar coal rank and petrographical compositions but different reducibility. The results show that C—C or C—H, C—O, C＝O, COO are four forms of carbon, and vitrinite has higher content of C—C or C—H than inertinite. The macerals of Pingshuo coal with stronger reducibility has higher content of C—C or C—H than those of Shendong coal with weaker reducibility. The forms of the other three elements in all samples are similar. The dominant form of oxygen is phenolic hydroxyl oxygen. Shendong coal macerals have higher capability of adsorbing oxygen than Pingshuo coal macerals, which is the reason that Shendong coal has lower ignition point and is easy spontaneously combusted. The dominant forms of nitrogen are pyridinic and pyrrolic type, while the thiophenic type is the main form of sulfur. The results indicate that the reducibility of coal influences the surface structure of vitrinite and inertinite, whose representation is the different content of C—C or C—H.
Abstract: The effects of pyrolysis temperature and heating rate on crystalline structures of Shenfu char were studied by using XRay Diffraction (XRD) technique. Shi et al.′s model[12,13]was adopted to quantitatively process the data of XRD patterns of chars and obtain the crystalline structure parameters of Basic Structure Unit (BSU). The characteristics and transformation of chars′ crystalline structure in the temperature range of 950℃~1400℃ were examined . Char gasification reactivity was investigated by using TGA. Under the conditions used in this study, it is found that the average stacking height (Lc) increases apparently and the carbon crystallite size (La) of the BSU changes little with the increase of pyrolysis temperature. It means that the coalescence growth of longitudinally adjacent BSUs dominates the growth process of BSUs in the temperature range used. Crystalline structure of chars becomes ordering with the increase of pyrolysis temperature but the graphitization is still not reached. Good correlation is also found between the heating rate and the char gasification reactivity. The chars generated from slow pyrolysis demonstrate a distinct low gasification reactivity as compared with ones from rapid pyrolysis. During slow pyrolysis, relative long resident time at high temperature leads to the further coalescence growth of longitudinally adjacent BSUs and the loss of lateral active sites of aromatic units. Crystalline structure of char reaching unity further would cause the chars less active.
Abstract: The gasification reaction characteristics of coal chars with CO2 at high carbon conversion were investigated by means of an isothermal thermogravimetric analysis at ambient pressure and at temperatures from 1200℃to 1400℃. The effects of gasification temperatures, heating rate and pyrolysis temperature on the gasification reactivity of coal chars were examined. The gasification reactivity of rapid pyrolyzed chars is found to be higher than that of slow pyrolyzed chars, and the general gasification reactivity of chars increases with gasification temperature. The gasification rate of rapid pyrolyzed chars is almost the same at gasification temperatures from 1300℃ to 1400℃. In addition, the ranges of the average apparent activation energies of slow and rapid pyrolyzed chars at the carbon conversion between 90% and 98% are 59.64kJ/mol～105.92kJ/mol and 34.47kJ/mol～40.87kJ/mol, respectively, which indicates that the gasification reactions have been controlled by gas diffusion.
Abstract: Pyrolysis, as a method of precombustion desulfurization of coal, is an effective approach to control SO2 emission in clean coal utilization. In this study, Yanzhou (YZ) coal was pyrolyzed in a fluidized bed reactor under 3.0%, 5.6% and 8.7% O2 N2 atmospheres and at the temperature range from 400℃ to 800℃. The sulfur distribution in gas and tar product was analyzed. The optimal desulphurization result with 3% O2 N2 atmosphere at 600℃ is reached, during which about 97% pyrite sulfur and 60% organic sulfur are released. However, under N2 atmosphere, at the same temperature, the desulphurization ratio of total sulfur and organic sulfur is only 25% and 15%, respectively. Under the oxidative atmosphere, the most of sulfur in coal is transferred into tar. With increasing the oxygen content of atmosphere, the char yields decrease quickly at high temperature. The decreasing degree of char yield is higher than the increasing degree of desulphurization rate. This suggests that the higher oxygen content would break C—C bonds severely when selectively breaking C—S bonds.
Abstract: The heat of oxygen reaction of low rank coals during low temperature oxidation under dry oxygen is measured using pulse calorimeter. The relation between the condensation heat and temperature at low temperature is investigated under wet nitrogen with relative humidity of 80% in order to study the effect of condensation heat on the low temperature oxidation of low rank coal. The results indicate that the heat of oxygen reaction increase with temperature under dry oxygen, but condensation heat decrease with temperature under wet nitrogen. Both kinetic equation of Arrhenius and activation energy are obtained under dry oxygen. It is also found that the condensation heat is much higher than the heat of oxygen reaction when the range of temperature is from 26℃ to 60℃. Therefore, the condensation heat is a key factor affecting the reaction of oxidation of low rank coal at low temperature.
Abstract: The dominating form of mercury is elemental Hg in high temperature coal combustion. With the decrease of flue gas temperatures the shift from Hg to HgCl2 takes place and a portion of HgCl2 is adsorbed by ash residue that is then collected by dedust equipment to decrease the mercury emission into air. In terms of mercury conversion in coal combustion, the mechanism is described via combining the thermodynamics model with adsorption model. The factors such as Cl concentration in coal and the decrease rate of flue gas temperatures and the residence time of flue gas were researched with numerical simulation in this paper. The results show that the mercury adsorption rate is over 40% when the Cl concentration in coal exceeds 0.08×10－6and the residence time of flue gas exceeds 6 seconds. The model is tested with the data from a 580MJ/h beachscale entrainedflow reactor with 150℃ of flue gas temperature , which testifies the model credibility.
Abstract: The performance of sawdust gasification in a 0.3m×0.3m bubbling fluidized bed gasifier (BFBG) is compared to that in the φ0.4m circulating fluidized bed gasifier (CFBG). The effects of fluidization velocity on the biomass gasification in two fluidized beds were analyzed. Due to the higher fluidization velocity and intensive mass and momentum transfer between gas and solids, CFBG has a faster pyrolysis rate than BFBG and can be operated at higher temperature with the same ER, which facilitates the second gasification and cracking of tar to improve the gas quality and reduce the tar content in gas. At low ER(ER≤0.28), the gas yield, carbon conversion and gasification efficiency of CFBG is higher than BFBG′s; however at higher ER(ER＞0.28), there is little difference between CFBG and BFBG.
Abstract: 〗Formation of NOx and HCl during gasification and combustion of Refuse Derived Fuel (RDF) was studied in a 4040mmhigh fluidized bed with two different crosssectional area. When temperature is lower than 640℃, chlorine removal by Ca(OH)2 is higher during NaClcontaining RDF combustion in the fluidized bed. HCl concentration in flue gas significantly increases with temperature increase because of enhancement of decomposition reaction undergoing chemical reaction balance of CaCl2. Higher oxygen content in flue gas and higher nitrogen content in the RDF result in higher NOx emission.
Abstract: Dagang vacuum residue was cut into sixteen fractions with supercritical fluid extraction and fraction (SFEF) instrument. The tailing was degraded by ruthenium ions catalyzed oxidation (RICO) reaction. From this reaction, homologous series of n alkanoic acids, α,ω di n alkanoic acids and benzenepolycarboxylic acids were detected and measured after esterification with diazomethane or phenacyl bromide. Wherein, n alkanoic acids represented aromaticattached n alkyl side chains, α,ω di n alkanoic acids presented the structure features of the polymethylene bridges between two aromaticunits, and those benzenepolycarboxylic acids indicated the major mode of aromatic condensations in the tailing. The products identified in this study show that the structure features of SFEF tailing, especially aromatic condensations mode, are not same as those results reported. Such information is very useful and important for the deep processing and optimizeuse of Dagang vacuum residue.
Abstract: Tahe naphthenicbase atmospheric residue was catalyticallyhydrocracked in a magneticstirred autoclave with oilsoluble MoDTC. The two solid acids (USY and HY), two solid bases (CaO and MgO) and two radical initiators (2, 2′Azobisisobutylonitrile and bitertbutyl peroxide) have been introduced into the system to improve the hydrocracking of residue. It is found that the solid additives including the acids and bases could considerably increase the cracking conversion and coke formation, especially the later. The initiators AIBN and BBPO could greatly improve the hydrocracking conversion of the residue so that the yields of cracking products increase and the coke yields hardly increase. The effects of the radical initiators at lower reaction temperature are better than that at higher temperature. The improvement with BBPO is more remarkable than that with AIBN.
Abstract: The gas phase oxidative cracking (GOC) of decane and hexane has been investigated in this paper. The higher performance of reaction and decoking were obtained in the GOC processes, as compared with their pyrolysis processes. At lower temperature, GOC process of decane is more suitable for producing liquid compounds, as well as low alkenes. A lower alkene yield of 13.1% and liquid yield of 37.4% were obtained in GOC of decane under the condition of 500℃ and n(C)/n(O)=2.5. For GOC of longchained alkane, O2 participates primarily in the oxydehydrogenation reactions at low temperature while it takes part in the oxidation reactions to produce COx (x=1,2) at high temperature,. Under the same reaction conditions, a higher ring opening activity was obtained in GOC of decane compared with that in GOC of hexane.
Abstract: Three different methods were used to synthesize the nano zirconia, including coprecipitation method (the sample marked as ZrO2CP), ethanol thermal method (the sample marked as ZrO2ET) and solidstate method (the sample marked as ZrO2S). The techniques of XRD, BET and SEM were used to characterize the structural and surface properties of zirconia. The results showed that ZrO2S synthesized by solidstate method was of better structural properties with larger BET surface area, more narrow pore size distribution and uniform particle size distribution. Methane reforming with carbon dioxide was used as the probe reaction to compare the activity and stability of the Ni based catalysts using ZrO2 as the support, which was synthesized by different methods. The reaction results show that Ni/ZrO2S catalyst exhibits the best catalytic activity and stability.
Abstract: The effects of MgO promoter on the physicochemical properties and the catalytic performance of Ni/Al2O3 catalysts for partial oxidation of methane to syngas were studied by BET, XRD, H2 TPR, TEM and reaction activity evaluation. It was found that MgO promoter benefited to the uniformity of nickel species on the catalysts, inhibited the formation of NiAl2O4 spinel and improved the interaction between nickel species and the support. This result was related to the formation of NiOMgO solid solution and MgAl2O4 spinel. Moreover, for the catalysts with proper amount of MgO promoter, the dispersion of nickel species was enhanced, and thus their catalytic performance for methane partial oxidation to syngas was improved. However, excessive MgO promoter exerted a negative effect on the catalyst performance. In addition, the basicity of MgO promoted the reverse watergas shift reaction, which led to the increase of CO selectivity and the decrease of H2 selectivity. The suitable content of MgO promoter in Ni/Al2O3 catalyst was about 7%.
Abstract: Hydrogen production from ethanol steam reforming has been investigated over nickel catalysts with respect to the nature of the support, the metal loading and calcination temperature. It was found that the Ni/CeO2 catalyst with Ni loading of 15% is more active and selective toward hydrogen production. Increasing the calcination temperature results in the agglomeration of NiO and CeO2 particles, and consequently decreases the reforming ability of the catalyst. Namely, smaller particles favor the ethanol steam reforming, while larger NiO and CeO2 particles promote the decomposition of ethanol. Mechanistic study by adding CO, CO2 and CH4 to the reaction stream at 350℃ further suggests that methane is produced by the direct decomposition of ethanol and/or acetaldehyde, instead of the methanation reactions of CO and CO2.
Abstract: TPR，XRD，XPS and H2pulse adsorption were used to investigate the influence of zirconia on the stability of Co/SiO2 catalyst for FischerTropsch synthesis. The results showed that the Co dispersion and the stability of the catalyst were both improved obviously as ZrO2 was introduced. Zirconia acted as a structural promoter and restrained the formation of the cobalt silicate and/or hydrosilicate species during the reaction.
Abstract: A short residence time flow equipment for the measurement of the critical temperature and pressure of fluids was developed to determine the critical properties of endothermic hydrocarbon fuels. The short residence time (about 10s~50s) at elevatedtemperature minimized the decomposition and other reactions of fuels. Taking n-pentane, n-hexane and cyclohexane as standard reagents, the reliability of the apparatus was checked. The critical properties of endothermic hydrocarbon fuelsSimulate JP-7 and RP-3 were determined. Four estimation methods based on the volume average boiling point and relative density were also used to estimate the critical properties of the fuels. The comparisons between the experimental and predicted values indicated that the correlations suggested by API (American Petroleum Institute) and RiaziDaubert were reliable to predict the critical properties of fuels.
Abstract: The effect of methyl tert butyl ether (MTBE) addition into gasoline on the exhaust emissions from EFI gasoline engine was studied. A four cylinder HL495IQ engine was used in the experiments. Fuels containing 0,5%,10%,15%,20% MTBE were used in the engine operations, and the exhaust gases were analyzed for CO, HC and NOx, before and after their catalytic treatment by a threeway catalytic converter. The addition of MTBE into gasoline resulted in a decrease in CO, THC and NOx emissions only at low speed or light loading. No obvious effect were observed at other conditions. Catalytic conversion efficiencies of CO and THC were inproved to 70% and 99% respectively. But the catalytic conversion rate of NOx only reached 12%~55%. The efficiency of catalytic converter had relations to speed, load of the engine and the MTBE content in the blended fuels.
Abstract: The activated carbon supported Pt(Pt/C) and the mixture of the activated carbon and the graphite supported Pt(Pt/CG) catalysts were prepared using chemical reduction method. It was found that the weight ratio of the activated carbon and the graphite could affect the electrocatalytic activity of the Pt/CG catalysts for ethanol oxidation. When the weight ratio of the activated carbon and graphite is 15∶1, the Pt/CG catalyst shows the best electrocatalytic activity for ethanol oxidation. It is mainly attributed to the high dispersion of the precipitated Pt particles and the large electrochemically active area when the weight ratio of the activated carbon and the graphite is suitable. In addition, the addition of graphite would increase the conductivity of the catalyst.
Abstract: Zeolite MCM-22 was synthesized by vaporphase transport method (VPT) with sodium silicate as silicon source, aluminium sulfate as aluminum source and HMI as the template. The characterization of xerogels was carried out using29Si MAS NMR,27 Al MAS NMR, FTIR and TEM. The effect of pH value on the structure of xerogels and synthesis of MCM-22 was investigated. It was indicated that the structure and the proportion of different composing aluminium silicates of xerogels were changed with pH value. The periods for the hydrosol turning into hydrogel increased with the increase of the pH. The xerogels had different particle sizes and properties in the different pH conditions. The alkalinity of the xerogel had very important impact on the crystallization of MCM-22. The pure MCM-22 was obtained when the pH of preparation hydrogels was between 8.7 and 10.7. MOR appeared partially when the pH value reached 11.1 and pure MOR was obtained when the pH was 11.6.
Abstract: NiB/SiO2 amorphous alloy catalyst was prepared by power electroless plating method and characterized by ICP, BET, TEM and XRD techniques. The catalytic performance of NiB/SiO2 was investigated for the hydrogenation of furfuryl alcohol（FA）to tetrafurfural alcohol（THFA）. The effects of operation conditions, such as reaction temperature, pressure, stirring rate were carefully studied, and the proper conditions were determined as the following: pressure 2.0MPa, temperature 120℃, stirring rate 550r/min. A typical result with FA conversion of 99% and THFA selectivity of 100% was obtained under such conditions, which is close to that of Raney Ni.
Abstract: In this paper, the CFD (Computational Fluid Dynamics) with EulerianEulerian model was used to simulate the gas and solid flow behaviors in the ashagglomerating fluidized bed gasifiers with different structures of gas distributor and ash separator. From the modeling results, the behaviors of gas and solid circulation flow with varying gas velocities of the central tube, and the impact of the slope angle of the annular tube on the gas flow and on the solid particles movement can be understood, which could help to improve the process of ash agglomeration and separation in the fluidized bed gasifier.
Abstract: The contracting and expanding processes of liquidsolid flow have been analyzed theoretically and simulated numerically in a twodimensional fluidized bed using the commercial Computational Fluid Dynamics (CFD) code, CFX4.4 with water and glass beads as the liquid and solid phases. A liquidsolid bed in equilibrium would transfer to a new equilibrium state after the liquid flux changes greatly. When the liquid flux is suddenly decreased, the bed is divided distinctly into two zones: an upper zone and a lower zone. The liquid volume fraction keeps the original value at the upper zone, whilst the liquid volume fraction becomes a new value corresponding to the new liquid flux. In fact, there exists a narrow region between the above two zones, which can be regarded as the “internal interface”. Bed surface and internal interface change linearly with the simulated time although the bed surface and internal interface moved downwards and upwards, respectively. When the liquid flux is suddenly increased, both the bed surface and internal interface rising with time are in nonlinear form, which is attributed to an influence of the gravitational instability. However, the effect of the simulated period of the expansion process on the response time of the contracting process can be neglected. The idealized expansion response time is close to the contraction response time, which is far shorter than the simulated value. All simulated data are in fair agreement with the theoretic and experimental data reported by other researchers.
Abstract: The effects of process variables on the heat transfer between an immersed heating element surface and solid/liquid mixture were investigated in a bubble column of 98mm i.d. The reactor was fitted with an axially mounted immersed heater which was made of copper with 20mm od and 120mm long. In order to simulate the system of the slurry phase FischerTropsch synthesis, the three phase system was composed of nitrogen, paraffin liquid, quartz sand of mean particle diameter 53μm,110μm,180μm or Fe2O3 powders less than 63μm. Process variables were examined in the following range: superficial gas velocity 0.005m/s～0.08m/s, temperature 353K～453K, pressure 0.1MPa～0.8MPa and solids concentration 0～20%. Three types of gas distributor were used in this study. A dimensionless correlation for the heat transfer coefficient is obtained by the leastsquare regress and presented as follows: St=0.179(ReFr)－0.25Pr－0.66. It fits the experimental data with an average deviation of 18% and can be applicable to both a gasliquid and a gasliquidsolid system with small particle less than 100μm.
Abstract: Biodesulfurization of coal by rhodococcus sp. was studied. Some kinds of coal were swelled with different organic solvents, and then the swelled coals were treated by rhodococcus sp. The results show that the ratios of desulfurization of coals increase after they are swelled, especially swelled with NMP, the ratio is more than 80%. On the other side, the swelling and extraction of coal were also studied after the coal had been treated by rhodococcus sp. The results show that the ratios of swelling increase more than 65%, but the extraction yield decreases for the coal treated by rhodococcus sp.
Abstract: The oxidation of dibenzothiophene (DBT) in decalin (as solvent) was conducted using oilsoluble oxidant tertamyl hydroperoxide (TAHP). The effects of oxidant amount, reaction temperature, reaction time and catalyst were investigated in detail. The results showed that under the condition of ratio of TAHP to sulfur 3∶1, reaction temperature 90℃, reaction time 3h, the desulfurization rate was up to 95%. The catalyst was necessary to oxidize DBT with TAHP. Weak acid cationic exchange resin of “D113” large aperture acrylic acid series supported MoO3 catalyst has relatively high activities. After the repetitious use as catalyst for 10 times, it still has good activity.
Abstract: The effects of heating rate and particle size on degradation of polyethylene to oils in supercritical water were investigated with a 125mL autoclave. The results show that with the increase of heating rate, the yield of oil increases and that of gas decreases. In addition, the fraction of heavy hydrocarbons and the ratio of 1alkene to n-alkane are relatively high under higher heating rate. More gas products and alkenes are produced using small particle polyethylene as raw material.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
