Abstract: The effects of thermal pretreatment on pyrolysis behavior of Shengli lignite were investigated in a fixed bed reactor. In comparison with raw coal, the thermally pretreated coal has lower content of hydroxyl group and lower ratio of aromatic-H to aliphatic-H. The yield of pyrolysis water is lowered after thermal pretreatment in N2, N2+O2 and CO2 atmospheres. The pretreatment also causes a higher CO2 content in pyrolysis gas, which thus lowers the heating value of the gas. Pretreating the coal in superheated steam raises the tar yield by 3~4 weight percentage points, and the composition of tar varies with the atmosphere and temperature of the pretreatment. The light fraction (with boiling points below 360℃) increased by 27 weight percentage points by pretreatment in 200℃-steam. The pretreatments at 200 and 250℃ in the mixture of steam and simulated flue gas elevate the light oil and phenol oil fractions in tar by 60 and 42 weight percentage points, respectively.
Abstract: To investigate the effects of acid pretreatment on the structure and pyrolysis performance of brown coal with high sulfur content, the brown coal from Ximeng, Inner Mongolia was selected, and leached by HF, HNO3 and HCl solution step by step. The pyrolysis performance and structure characteristics of Ximeng raw coal and different acid treatment coal samples were studied in detail by means of thermal gravimetric analysis and FT-IR technique, and the pyrolysis kinetics was also analyzed. The results show that the structure of coal sample is not significantly affected by the HF treatment process, but an obvious organic structure change is found in the coal samples further treated by HNO3 solution. The intensity variation of absorption peaks of aliphatic groups CH3 caused by HNO3 is weakened by the HCl treatment process. The pyrolysis performance of Ximeng brown coal can be changed by the fractional step acid treatment. HF and HNO3 treatment processes promote the reactivity of coal pyrolysis, and the further treatment of HCl solution only has a slight influence. The kinetics analysis of coal pyrolysis reveals that the effect of different acid treatments on the pyrolysis characteristics of Ximeng brown coal can not be described only by the apparent activation energy of pyrolysis reaction. There is a compensation effect between pyrolysis activation energy and pre-exponential factor, besides, the pyrolysis activation energy relates to the weight loss of coal pyrolysis.
Abstract: The steam gasification of Jinshan petroleum coke catalyzed by potassium salts was investigated in a laboratory fixed-bed reactor, in which the catalytic effects on the gasification activity and the H2 production characteristics were examined. It is observed that the potassium salts can not only effectively lower the gasification temperature and greatly enhance the gasification activity of petroleum coke, but also promote the carbon-water reaction, the water-gas shift reaction and the methane-steam reforming reaction. With the increasing of gasification temperature, the H2 content in gas for non-catalytic gasification increases gradually, while that for the catalytic gasification decreases somewhat, which is probably ascribed to the different behavior of water-gas shift reaction during catalytic gasification. Compared with non-catalytic gasification, the catalytic gasification of petroleum coke can generate a higher hydrogen yield and content (the content of H2 is in the ranges of 47.2%~54.1% for non-catalytic gasification and 55.0%~60.4% for catalytic gasification). The ordering of the catalysis for various potassium salts is K2CO3>KAc>KNO3>K2SO4>KCl, but the type of potassium salts has no effects on the distribution of product gases.
Abstract: Effect of temperature and residence time on coal-nitrogen transformation during pyrolysis of 3 coals from west China was studied in a fixed bed reactor. The results show that the duration time of HCN releasing is about 3 min at 1 073 K for pyrolysis of coal A. The start release time of HCN is earlier than that of NH3, and the released amount of HCN quickly drops to zero as NH3 starts to release. The accumulated release amounts of HCN and NH3 first reach the maximum value at different pyrolysis time and then decrease sharply. The yield of char-nitrogen increases with increasing temperature. At 973~1 123 K, about 50~60 mass percentage of the coal-nitrogen exits in char as char-nitrogen and the rest is released as volatiles, in which about 20~50 mass percentage of the volatile-nitrogen is NH3 and HCN. The mass percentage of NH3 accounts for 40%~50% and that of HCN about 50%~60% in the volatile-nitrogen.
Abstract: The cycle experiments on chemical looping combustion of coal were carried out in a fluidized bed using a K-promoted iron ore as oxygen carrier. The continued effect of the K-promoted iron ore on the gas compositions, fractions of carbonaceous gases was investigated.The results showed that the reaction time was shortened by the K-promoted iron ore,and that the CO2 concentration was significantly increased.The CO2 fraction for the K-promoted iron ore was much higher than that for the iron ore whereas,the CO fraction was much lower during 20 cycles.After 11 cycles, the CO2 fraction slightly decreased with a slight increase in CO fraction for the K-promoted iron ore. The reduced oxygen carriers after different cycles were characterized by SEM-EDS (Scanning Electron Microscope-Energy Dispersive Spectrometer) and XRD (X-ray diffraction).Compared with pure iron ore, the K-promoted iron ore showed serious sinter on the oxygen carrier particles during the first 11 cycles. The oxygen carrier, however, re-obtained the porous structure after 20 cycles due to the loss of potassium.The XRD showed that the KFe11O17 or its derivatives displayed the catalytic effect on coal gasification in the process of chemical looping combustion and the oxygen carrier could be regenerated to Fe2O3 after 20 cycles.
Abstract: The reaction mechanisms between free radicals NO and NHi were studied using quantum chemical density functional theory (DFT) and rate constant for each reaction was calculated combining with classical transition state theory in this paper. The results show that there are six different reaction channels for free radicals NO and NH2, and the products are N2+H2O, N2O+H2 and N2H+OH. The optimum reaction channel is NO+NH2→→N2+H2O from the views of energy change and reaction rate. Similarly, N2+OH, N2O+H and N2H+O will be produced by seven different reaction channels between free radicals NO and NH, and the optimum reaction channel is NO+NH→→N2+OH. So it is easier for free radical NH reacting with NO to generate N2 than NH2. Therefore, an important conclusion was got that the lower NOx emission could be obtained by making NH2 turn to NH in the actual operation.
Abstract: It is a feasible way for large-scale use of biomass by co-gasification of its char with coal. And the alkali metal salts contained in the biomass can act as the catalyst during gasification. Several co-gasification experiments between coal and straw char were carried out by thermal gravimetric analysis in non-isothermal mode under CO2 atmosphere at the heating rate 20℃/min and the final temperature 1 200℃. The results show that there is no synergy between the two fuels during the pyrolysis stage, however, an obvious synergy effect is found in gasification stage when the temperature is greater than 800℃. Compared with the results calculated without considering the synergy, the coal gasification reaction is promoted when some straw chars are added. As a result, the final gasification temperature is lowered by 26℃ and the maximum weight loss rate is increased by 22%. The synergy is mainly due to the catalysis of the alkali metal in rice straw. The kinetic analysis shows that the gasification activation energy of the blend fuel is lower than that of coal alone.
Abstract: A new upgrading method of pyrolysis-oil was proposed to improve the quality of pyrolysis-oil to be an engine fuel. First, the raw pyrolysis-oil was treated by the combination of ether extraction and chemical catalysis. Secondly, the upgrading pyrolysis-oil/diesel blends were prepared by the ultrasonic treatment. The value of S, which is defined as the volume of upgrading pyrolysis-oil dissolved in a unit volume of diesel, was used for evaluating the emulsification of the blends. The results show that the amount of emulsifier plays an important part in the value of S. When the volume ratio of upgrading pyrolysis-oil, diesel and emulsifier equals 10:30:5, the optimal experimental condition is that the ultrasonic time is 20 min, the ultrasonic power is 540 W, the temperature is 50℃. By analyzing the physical characteristics, the blends are found to be stable and have a good combustion performance, which can be a promising alternative to diesel.
Abstract: Using optical structure analysis as the main characterization methods, the course of shot coke formation and the effects of feedstock properties and operating conditions were investigated in a small scale experiment equipment. After analysis of reasons for shot coke formation, the corresponding suppression measures were suggested. The results show that the course of shot coke formation can be expressed as feedstock → unstable spheres of mesophase → mosaic mesophase → shot coke. When the ratio of asphaltene to carbon residue is higher than 0.5, the atomic ratio of H/C is below 1.5 and the colloidal stability parameter is less than 3.5, the shot coke is easily formed. Various circulation fractions play different roles in inhibition of shot coke formation. When using heavy coker gas oil (HCGO) (420~500℃) as circulating fraction the best effect is obtained. The shot coke formation can be inhibited by optimizing process parameters like adoption of lower temperature, higher pressure, higher recycle ratio and adding tetrahydronaphthalene or fluid catalytic cracking (FCC) slurry to the reaction system.
Abstract: Electroactive biofilms were formed on carbon paper under constant external resistance of 1 000 Ω using Escherichia coli as inoculum and glucose as substrate. In this paper, the performance of the biofilm growth of the microorganism directly on the anode was studied. To form a mature biofilm, five fed-batch cycles were repeated with every period of 1 day. The electrochemical characterization of the microbial fuel cell was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and polarization behavior. It was evident that the enhanced MFC performance was associated with the development of the biofilm. With formation of the mature anode biofilm, the anode polarization resistance was decreased by 66.5%, the anode potential also gradually decreased, while peak output power density was enhanced over 260%.
Abstract: MgO/NaY catalyst was prepared by a simple and green procedure and used in the aldol condensation of furfural and acetone to produce jet fuel intermediates in a water-ethanol solvent; the effects of MgO loading, feedstock composition, reaction temperature and time on the product distribution were investigated. The results indicated that the 20%MgO/NaY catalyst performs best in the aldol reaction; the conversion of furfural reaches 99.6% after reaction at 85℃ for 8 h, while the selectivities to furfural-acetone (FA) and di-furfural-acetone (F2A) are 42.2% and 57.1%, respectively, with a yield of condensation products of 98.6%. High temperature may enhance the degradation of F3A2 intermediate and therefore improves the selectivity to aldol products. The product distribution can be adjusted by changing the feedstock composition; the selectivity to F2A increases with the increase of the ratio of furfural to acetone, at the expense of a slight decrease of the reaction rate. The spent catalyst shows a good regeneration capability; its catalytic activity is well recovered after calcination treatment.
Abstract: The pyrolysis of 2,3,4-hydroxyl-butyraldehyde and 2,3,4-hydroxyl-butyric acid as model compounds was investigated by using B3LYP/cc-pVTZ methods to reveal the decarbonyl and decarboxyl mechanism. Three possible pathways for the pyrolysis of each model compound were designed and the standard thermodynamic and kinetic parameters of each reaction path at different temperatures were determined. The results showed that the release of CO and CO2 during the cellulose pyrolysis is related to the decarbonyl and decarboxyl reactions, respectively; both involve a concerted process via intra-molecular hydrogen transfer. Decarboxyl reaction is endothermic while decarbonyl reaction is exothermic. The activation energy of decarbonyl reaction of 2,3,4-hydroxyl-butyraldehyde is 288.8 kJ/mol, while the activation energy of decarbonyl reaction of undersaturated olefine aldehyde after dehydration is higher than that for saturated aldehyde. The activation energy of decarboxyl reaction of 2,3,4-hydroxyl-butyric acid is 303.4 kJ/mol, while the activation energy of decarboxyl reaction of undersaturated olefine acid after dehydration is much lower, indicating that the dehydration favors the release of CO2.
Abstract: Au-Pd/SiO2 catalysts with different calcination temperatures were prepared by sol-immobilization method; their catalytic performance in oxidation of methanol to methyl formate was investigated. Among 200~500℃, Au-Pd/SiO2 catalyst calcined at 400℃ exhibits the best catalytic activity in the topic reaction at room temperature, and 25.3% methanol conversion with 100% selectivity to methyl formate can be achieved at100℃. They were characterized by BET, XRD, UV-vis DRS, XPS, TEM and DRIFTS. Good dispersity of Au and Pd, proper particle size of Au and Pd, the formation of Au-Pd bimetallic nanoparticles, and strong interaction between Au and Pd in the Au-Pd/SiO2 catalyst are beneficial to the oxidation of methanol to methyl formate. Furthermore, a preliminary reaction mechanism of methanol oxidation to methyl formate on the Au-Pd/SiO2 catalyst is inferred and methyl formate is gained from intermediate species methoxy in this reaction mechanism.
Abstract: NiY zeolite was synthesized through hydrothermal method, in which Ni was incorporated into the zeolite framework. With NiY and Y zeolites as the supports, a series of hydrocracking catalysts were prepared and characterized by XRD, SEM and NH3-TPD; their catalytic performance in hydrocracking was evaluated in a fixed-bed reactor. The results indicated that the surface acidity of Y zeolite can be modified through introducing Ni into the framework. Compared with Ni-Mo/Y catalyst with Y as support, Ni-Mo/NY catalyst with NiY as support has more total acid sites but less strong acid sites; as a result, it exhibits higher cracking and desulfurization activity, higher stability and less coke deposition.
Abstract: 4 series of catalyst with different Ni loadings, including Ni/ZSM-5, Ni/HY, Ni/Al2O3 and Ni/USY,were prepared by volumetric immersion method. The catalytic performance of the prepared catalysts for phenanthrene hydrocracking was evaluated using a fixed bed reactor. BET and SEM were used to obtain the catalysts' phase structure, surface area and average pore size. The carbon deposition of catalysts after reaction were measured by TG/DSC. The results showed that 12% Ni loading on HY and USY zeolites had best catalytic activity for phenanthrene hydrocracking with the BTX yield of 52%. As to Ni/Al2O3 the best nickel loading was 6%, and this catalyst just had a good catalytic activity at beginning and deactivated quickly. Ni/ZSM-5 had poor catalytic activity.
Abstract: The removal of NO by viscose base activated carbon fibers were carried out on a fixed-bed adsorption reactor. The methods such as hydrogen peroxide (H2O2) solution impregnation, heat treatment were employed separately to modify the activated carbon fibers. The NO removal efficiency was investigated using the activated carbon fibers before and after modification in the inert nitrogen atmosphere, oxygen-containing atmosphere. Furthermore, the change of activated carbon fibers characteristics, such as pore structure as well as nitrogenous or oxygenous surface functional groups, was also discussed in order to explore the effect of oxygen-containing functional groups and O2 in atmosphere on the NO catalytic oxidation and the transformation process of NO to NO2. The results show that in the nitrogen atmosphere the C-O functional groups of the activated carbon fiber surface can oxidize the adsorbed NO to be -NO2. On the other hand, in the oxygen atmosphere -NO2 and -NO3 are detected in the activated carbon fibers surface after the NO adsorbing. It is found that NO removal efficiency in stable stage after long time test is almost the same for the original activated carbon fibers as well as the two modified ones, which indicates that the transformation of NO to NO2 is mainly resulted from the reaction between the adsorbed NO on activated carbon fibers and the free oxygen in atmosphere.
Abstract: The desulfurization of diesel oil was conducted via oxidation-adsorption process, using H2O2 as oxidant in the presence of amphiphilic catalyst and mesoporous silica-gel as the adsorbent. The fixed-bed dynamic adsorption method was employed to evaluate the oxidation-adsorption desulfurization capability of the catalysts and the effects of the property of silica-gel, oxidation and adsorption conditions on desulfurization efficiency were investigated. It was proved that the silica-gel possessed the mesoporous structure characterized by small-angle XRD and N2 adsorption-desorption isotherm. Compared with adsorption process, oxidation-adsorption process could availably increase the adsorptive capacity and selectivity of silica-gel adsorbent to sulfur compounds in diesel oil.The sulfur removal efficiency remained as high as 85.89% when the volume ratio of diesel oil to silica-gel was 15. Sulfur removal efficiency reached up to 94.57% when adsorption temperature, space velocity and volume ratio of diesel oil to silica-gel were 40℃, 6.0 h-1 and 1 respectively.
Abstract: An activated coke was modified by HNO3. The influences of HNO3 concentration, activation temperature, activation time and calcination temperature on surface properties the activated coke were investigated by orthogonal experiments. The SO2 adsorption capacities of the modified activated coke were examined in a fixed bed reactor. The surface acidity-basicity, specific surface area and pore structure coke were characterized by acid-base titration, N2 adsorption, iodine adsorption value and Fourier transform infrared spectrometry, respectively. The results show that HNO3 modification raises the specific surface area and surface basicity of the activated coke. Calcination improves the surface basicity. HNO3 modification obviously enhances the desulfurization performance of the activated coke.
Abstract: The Cd and Pb volatilization behavior in model solid waste in a fluidized bed incinerator with Al2O3 bed material was investigated. The influence of redox conditions, H2O, HCl, SO2 and Al2O3 was examined. The results show that Cd has a great volatility, especially when HCl is added, while Pb volatilizes moderately. Increasing the oxygen concentration can lower the heavy metal volatilization. The sorption (either physical or chemical) of Al2O3 particles, coupling with the internal diffusion of gaseous metal species, may control the volatilization of heavy metals. When SO2 is added, Cd and Pb show a higher volatility.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
