Abstract: The entrained-flow pulverized coal gasification process was thermodynamically analyzed by Gibbs free energy minimization method. For a given coal , the effects of oxygen-coal ratio and steam-coal ratio on the crude syngas composition, gasification temperature and the yield of CO+H2 were studied under the operating pressure of 3.0 MPa and gasification temperature ranging from 1 200 ℃ to 1 450 ℃. The thermodynamic analysis results of the reasonable operation ranges (545 m3/t to 605 m3/t coal for oxygen-coal ratio and 152.64 kg to 319.32 kg steam/t coal for steam-coal ratio) and the corresponding gasification performance (typically, CO+H2 91.5 v%(dry base), gasification temperature 1 358 ℃ and syngas yied of 2.123 CO+H2 m3/kg coal) are obtained. At the same time, the study of the effects of carbon conversion efficiency and heat lost on the gasification performance shows that the effects are remarkable.
Abstract: The effects of acid-base deashing treatment on the organic constituents, surface properties and slurryability of Hebi, Huainan, and Jingyuan coals have been studied. The results show that many properties of coal are changed by deashing treatment. The content of ash, volatile, sulfur and oxygen of the acid-base treated coals decreases compared with that of the raw coal. However, the content of moisture, phenolic hydroxyl oxygen, total and aromatic carbon in the treated increases. The slurryability of coal is weakened by acid-base treatment. Under the given conditions of coal particles distribution, additive and its dosage, as compared with raw coal, the CWS concentration under the viscosity of 1 000 mPa·s decreases by 4.6%, 6.6% and 4.4% for Hebi, Huainan and Jingyuan coals, respectively. The adsorption amounts of different dispersants on the deashed coals and Zeta potentials increase. Evidently, the lower slurryability of the acid-base treated coals is mainly due to the change of organic constituents and surface properties of the coals.
Abstract: The experiments on the combustion of volatile and char of anthracite were carried out separately in a fixed-bed reactor. The NO release characteristics of volatile N and char N combustion and the relative contribution of volatile N and char N to NO formation of coal combustion were studied. It is found that coal N, volatile N and char N conversion increases as the excess air coefficient and temperature increase. Char N is the primary resources of NO formation during anthracite combustion. The coal N conversion is less than the total conversion of volatile N and char N, which is resulted from the interaction between volatile and char during coal combustion as it is in the reductive or oxidative atmosphere.
Abstract: The reversible reaction of gas desulfurization by CaO was investigated using a thermal balance and a fixed-bed reactor. The results show that there is an optimum desulfurization temperature，i.e. the decomposition temperature of Ca(OH)2 in the absence of carbon dioxide, and the steam and hydrogen have different effects on the reversible reaction of desulfurization. Increasing the concentration of steam benefits the reverse reaction both in thermodynamics and kinetics, which decreases the efficiency of desulfurization. However, the effect of hydrogen on the reverse reaction at high temperature is negative. As the concentration of hydrogen increases to a certain value, the reverse reaction becomes a single reaction instead of multiple reactions, and the efficiency of desulfurization can be determined by the thermodynamic properties of reaction (CaO + H2S = CaS + H2O). In addition, the possibility to use the CaS/ H2O reaction to deal with the waste CaS is discussed.
Abstract: The decompositon of CaSO4 is the key reason for the low efficiency of the desulphurization in grate furnace. In this paper , the decompostion of CaSO4 was investigated by means of a Metteler Toledo TGA with a infrared spectral analyzer for exhausted gas under isothermal condition. The mass fraction of CaS in final solid product was analyzed with the spectrophotometric measurement using ethylene blue. CaSO4 is converted to CaO and CaS simultaneously by parallel reactions under CO atmosphere. Under 0.5%CO atmosphere, CaSO4 is mainly converted to CaO. However, under 4%CO atmosphere CaSO4 is mainly converted to CaO in initial stage and CaS in latter stage. The mass fraction of CaS in final solid product increases with increasing the concentration of CO and decreases with increasing the temperature. The model of parrallel reactions could depict the decompositon of CaSO4 well under CO atmosphere.
Abstract: In this paper, the slurryability (the concentration of slurry that has the apparent viscosity of 1 200 mPa·s at shear rate of 28.38 s－1), rheological behaviour (represented by flow index), and static stability (showed by the days of formation of soft sediment) of coal water slurry prepared from 24 Chinese coals from different districts with different coal ranks from lignite to anthracite were investigated. Sodium naphthalene sulfonate formaldehyde condensate was selected as the dispersant The testing results indicate that the slurries prepared from six coals of FF、KL、XW、XHY、WL、YM have higher slurryability up to 66% and better static stabilityof about 15 d. Their rheological behaviour of slurries exhibits pseudo-plasticity. It is found that higher slurry concentration with static stability of 7 d can be obtained from three coals of SGJ、HN、ST, but their rheological behaviour of slurries shows dilate-plasticity. The slurries prepared from the coals of BY、HH、HB had higher slurryability but poor rheological behaviour and static.
Abstract: The HCN and NH3 formation during tar secondary pyrolysis for four Chinese coals was investigated with a two stage fixed-bed quartz reactor at 600 ℃～1 000 ℃. The influences of coal rank，ash content and temperature were examined. With the increase of coal rank，the nitrogen in coal tar decreases and the conversion of nitrogen to HCN and NH3 decreases. The conversion of nitrogen to HCN and NH3increases with temperature, and HCN reaches the highest yield in the range of temperature from 800 ℃ to 900 ℃. The presence of ash in coal can reduce the content of nitrogen in tar, which gives rise to the decrease of the yield of HCN and NH3 during the secondary pyrolysis of tar.
Abstract: The experiments on the premixed natural gas combustion and heat transfer were conducted in a bench-scale porous media burner. The porous media used is a kind of gradually-varied porous media. It is found that the premixed natural gas can burn steadily in the burner, and gas velocity and porous media thickness have influences on the temperature profile, exit gas temperature and pressure drop. Heat transfer coefficient between the flame and water in the jacket was measured. Experimental results show that the heat transfer is enhanced in the gradually-varied porous media, comparing to the free flame combustion. Meanwhile, a pressure drop along the burner increases as the gas velocity and porous media thickness increase.
Abstract: By means of GC-AED, the sulfur-containing compounds presented in the hydrotreated diesels obtained from bench-scale reactor were analyzed, and several questionable peaks were found in the chromatograms. The same questionable peaks were also found in the chromatograms of diesels before and after oxidation and extraction. By the analysis and conjecture it is thought to be the elemental sulfur's peak. Through the analysis of the sample by adding elemental sulfur into sulfur-free oils and washing the object diesels with mercury, these questionable peaks were identified as elemental sulfur. The reason for elemental sulfur formation in the hydrotreated diesels and the effect of elemental sulfur on the analysis of sulfur content of hydrotreated diesels are discussed in this paper. Moreover, if the diesels containing elemental sulfur and/or H2S were selected as samples in non-hydrodesulfurization test, such as oxidative desulfurization test, a wrong conclusion might be made due to the difficulties of removing elemental sulfur by oxidation /extraction. So the diesels not containing elemental sulfur and/or H2S should be chosen as the samples in non-hydrodesulfurization test.
Abstract: New bi-liquid phase catalytic systems containing two different types of strong Lewis acidic ionic liquids which do not dissolve in FCC gasoline, were employed to reduce the olefin content in FCC gasoline. It was shown that the olefin content decreases by 14.70% in［bmIm］Cl-AlCl3 ionic liquid system and 13.08% in \[R4N\]Cl-AlCl3 ionic liquid system, respectively, while the octane number of gasoline does not decrease. The olefin content of FCC gasoline after dealing with the ionic liquids is less than 35%, which has reached the national usage standard for clean FCC gasoline. The mechanism of olefin reducing in FCC gasoline was investigated in detail. It was the alkylation, dimerization and Frediel-Crafts reactions catalysed by the Lewis super strong acidic ionic liquids that caused the olefin reducing in FCC gasoline.
Abstract: Sodium lignosulphonate was fractionated by means of ultrafiltration, and 4 fractions of different molecular weights were collected. It is showed by FTIR that the 5 000～10 000 fraction has the maximum hydrophilic group such as hydroxyl, phenolic hydroxyl and sulfonic group. With the increase of molecular weight, the content of hydrophilic group decreases. The results show that the adsorption curve of 10 000～50 000 fraction on coal particles approximates L type which means more adsorptive capacity, and this fraction makes the zeta potential reach –52 mV. The slurrying experiment shows that the 10 000～50 000 fraction has the best dispersing performance to Panjiang coal among all fractions. Furthermore, it is concluded that the adsorptive capacity of the dispersant on coal particles and the zeta potential are the main factors affecting the dispersing performance.
Abstract: The basic properties of three fly ash samples taken from three different municipal solid waste (MSW) incinerators in China were explored by a serious of experiments, concerning their chemical composition, weight loss during calcination, melting point and leaching toxicity etc. The effect of chemical composition of fly ash on its chemical and physical characteristics as well as leaching toxicity was mainly investigated. It was found that physical and chemical characteristics of fly ash are mainly affected by the mass percentage of MgO, CaO, SiO2 and CaCl2. Fly ash with higher MgO and Al2O3 content and lower CaCl2 content has relatively higher melting point. Fly ash with higher CaO and CaCl2 content has relatively higher moisture and weight loss in calcination. Fly ash with higher SiO2 content has lower leaching rate of heavy metal.
Abstract: By means of thermogravimertric analysis (TGA), the influences of different catalysts on the ignition and burn off of municipal solid waste (MSW) combustion were examined in this paper. It shows that the catalysis of the catalysts to the MSW combustion is embodied in the enhancement of the emission of volatile matters (VM) from MSW, which reduces the ignition temperature. Another role of the catalysts to the combustion of MSW may be a carrier of oxygen that impromotes the oxygen transfer to the char of MSW. Two indexes have been put forward to describe the character of ignition and burnout of MSW. One is the temperature when the weight loss of MSW is 5%, the other is the burnout extent when the temperature is 850 ℃. By comparing the two indexes, different influences of catalysts to the ignition and burnout of MSW have been obtained. The relative active sequence of catalysts to the ignition of MSW is described as follows: K2CO3> MnO2 > Na2CO3> CuO > MgO > TiO2 > Al2O3> Fe2O3 > BaCO3> CaO；The relative active sequence of catalysts to burnout of MSW is described as follows: Na2CO3>MgO> MnO2> K2CO3> BaCO3> CaO> Al2O3> CuO> Fe2O3> TiO2.
Abstract: Fly ashes from municipal solid waste (MSW) incinerator were used to determine melting point and to perform differential thermal analysis. The weight loss and heavy metals distribution during calcination in air at different temperatures were discussed. It indicates that the minimum of weight loss is up to 27.5%. Melting reaction of fly ashes initially occurs at 1132℃ and exhibits the second melting reaction at 1252℃～1290℃. The proportions of Cr, Ni and Cu in melted samples increase with the elevation of their melting point and boiling point. The amounts of evaporation are above 95% for Pb, Cd, As, and Hg. The quantities of evaporation is in sequence of Pb>Cd>As>Hg. Zinc in fly ashes exists in the form of ZnO, which forms the nonvolatile compounds such as Zn2SiO4, ZnSiO3, and ZnAl2O4. The minimum rate of Zn evaporation in fly ashes is 66.7% at 1200℃.
Abstract: Biomass gasification under O2-rich gas was carried out in a fluidized bed reactor. The effects of equivalence ratio and volume fraction of oxygen on gas composition, carbon conversion and low heating value (LHV) of fuel gas were investigated through a series of experiments. Equivalence ratio (ER) is closely related to the bed temperature changed by adjusting the feeding rate. When ER varied from 0.21 to 0.29, the gas compositions were changed. The volume fraction of hydrogen increases apparently when the volume fraction of reducing species, such as CO and CH4, decreases. The volume ratio of oxygen is a very important variable to the biomass gasification. It is concluded that increasing volume fraction of oxygen improves the volume fraction of H2 and contributes to adjust H2/CO ratio to an appropriate value. When the volume fraction of hydrogen is increased from 20% to 27.7%, H2/CO ratio is improved from 0.38 to 0.75, which is adequate to synthesize the liquid fuel.
Abstract: Direct liquefaction of 5 agricultural residues was carried out in a 250 mL autoclave. During the tentative experiment, peanut shell was tested. The influence of reaction temperature, reaction time and catalyst etc. was investigated. The results show that 21%～28% of heavy oil yield is obtained under the conditions of 300 ℃～340 ℃, 10 min and 1/30 (K2CO3 catalyst/raw material, w/w), when feedstock is 10 g sample mixed with 100 mL water. A linear correlative model gives the correlation coefficient of 0.89, which denotes that the heavy oil yields have a good relationship with the lignin contents in agricultural residues. The heavy oils obtained from the liquefaction of agricultural residues have high heating values. This work shows that liquefaction is an effective way to convert agricultural residues to bio-fuels.
Abstract: Fundamental study of the reaction performance and stability of an industrial fixed-bed Fe-Cu-K catalyst was carried out by using a continuous stirred tank reactor (CSTR) equipped with a wax removal system under industrial relevant conditions: 255℃~290℃, 1.5MPa~3.1MPa total pressure, H2/CO (mol ratio)=0.50~1.52 and a space velocity of 1.0L /gcat·h－1~2.5L /gcat·h－1 (unreduced catalyst base) . The effects of reaction conditions on the catalyst activity, product selectivity and stability were investigated. The Scanning electron microscope (SEM) was used to investigate the catalyst attrition resistance. A 2 500 h slurry phase reaction result indicated that the changes of the process conditions (temperature, pressure, H2/CO feed ration and space velocity) had strong effects on the productivity and product selectivity. The effects of the adjustment of reaction pressure on the catalyst stability were particular obvious. The deactivation rates of the catalyst decreased with the changes of conditions in the following order: reaction pressure > space velocity > H2/CO feed ratios. The catalyst activity could be enhanced with the reaction temperature increasing, but the selectivity to heavy hydrocarbons was decreased. The increase of the reaction pressure could promote the conversion, and improve the heavy hydrocarbons selectivity and the hydrocarbon productivity. Increasing space velocity in feed gas could increase hydrocarbon productivity, and evidently decline the CO conversion and the selectivity of the heavy hydrocarbons. The increase of the H2/CO feed ratio could raise CO conversion and improve the selectivity of heavy hydrocarbons. The appropriate choice of the F-T reaction parameters in slurry phase could obtain the balance among catalyst activity, hydrocarbon distribution and productivity. The SEM results indicated that the catalyst exhibited robust attrition resistance.
Abstract: Magnesium-promoted Fe/Cu/K/SiO2 catalyst for Fischer-Tropsch synthesis (FTS) was prepared using spray-dried technology. The structures of the catalysts after calcination at different temperatures were characterized by means of N2 physisorption, X-ray diffraction (XRD), Mö ssbauer spectroscopy (MES), and H2 temperature-programmed reduction (TPR). It showed that increasing calcination temperature decreased the BET surface area and increased the average pore diameter and the size of α-Fe2O3 crystallite for the catalyst, leading to a difficult reduction of the active phase. The Fischer-Tropsch performance of the catalysts after calcination was tested in a fixed bed reactor under the conditions of 250 ℃, 2.0 MPa and 2 000 h－1. With the increase of the calcination temperature, the initial activity of the catalyst decreased, and the activity gradually approached to a stable value with time on stream, depending on the induction period which prolonged with increasing calcination temperature. Additionally, the increase of the calcination temperature also favored the formation of heavy hydrocarbons and declined the CH4 selectivity.
Abstract: The effects of calcination temperature on the properties of Ni/MgO-Al2O3 were studied by the means of XRD, TPR, BET，TG and catalytic performance evaluation. With the increase of calcination temperature of the catalysts, the interaction between nickel species and support became stronger, and NiAl2O4, MgAl2O4 spinel and NiMgO2 formed. Compared withγ-alumina, the Ni/MgO-Al2O3 catalysts showed larger specific surface area even at higher calcination temperature due to the formation of spinel. In the partial oxidation of methane to syngas, the Ni/MgO-Al2O3 catalysts calcinated at higher temperature exhibited better stability under the conditions of atmospheric pressure, 1 083 K, CH4/O2=1.8 and 2.66×105 h－1. Whether Ni/MgO-Al2O3 catalysts were calcined at low or high temperature, they all showed higher resistance to coking. In addition, the hotspot temperature of the catalytic bed for the catalysts calcinated at high temperature decreased, which benefits to prevent the catalysts from sintering.
Abstract: M/MoO3-TiO2(M=Pd, Cu, Ni, Ag) photocatalysts were prepared by sol-gel and impregnation-reaction method. The surface structure, adsorption property, photo absorption performance and photo catalytic performance of M/MoO3-TiO2 catalysts were characterized by XRD, TPR, IR, TPD, UV-VisDRS and photoreaction techniques. The experiment results showed that the supported metallic M (M=Pd, Cu) on coupled semiconductor MoO3-TiO2 restrains TiO2 transformation from anatase to rutile and improves the transformation from the tetrahedrally coordinated Mo oxide species to the octahedrally coordinated Mo oxide species. The blue shifting of photo absorption edge and increasing of the photo absorption capacity to visible light were observed clearly after the addition of metallic M (M=Pd, Cu, Ag) on the surface of MoO3-TiO2. The photo absorption decreases in the order of Pd/MoO3-TiO2, Cu/MoO3-TiO2, Ag/MoO3-TiO2 and Ni/MoO3-TiO2. It can be concluded that the adsorption of CO2 on Pd/MoO3-TiO2 is very strong, and its desorption temperature of horizontal adsorption state increases, thus its photo quantum efficiency is lower than that of Cu/MoO3-TiO2, on which desorption temperature for both CO2 and C3H6 is about the same. Loaded metallic Cu realizes “photo-surface-thermal” synergistic effects and improves photo quantum yield.
Abstract: The macrokinetics of vinyl acetate synthesis from acetylene and acetic acid on the Zn(Ac)2/super-high specific surface area activated carbon (AＢＥＴ=2 713 m2/g) catalyst has been studied under conditions approaching those of industrial operation, and compared with Zn(Ac)2/Japaniese coco-shell carbon (AＢＥＴ=1 384 m2/g) catalyst. The macrokinetics equations areυ1=28.22pＣ２Ｈ２1.00p VAc -0.62 and υ2=25.03pＣ２Ｈ２1.01 p VAc -0.52 for two kinds of catalysts, respectively. The average apparent activation energy are 52.49(kJ·mol-1) and 53.87(kJ·mol-1) for the catalysts at temperature range of 160 ℃~175 ℃, respectively. The results indicated that the reaction order to acetylene was one, and the reaction order to vinyl acetate was negative. The activation energy was less than real activation energy 87.80(kJ·mol-1), which indicated that the synthesis reaction was seriously affected by diffusion. The catalytic activity increased with the increment of the specific surface area of the catalysts support. At the same time, the catalytic activity was less affected by increasing in specific surface area of support at high temperature range of 185 ℃~195 ℃.
Abstract: The platinum catalysts supported on two series of supports (NaY, HNaY, HY and NaBeta, HBeta) were prepared to study the influence of electronic properties of platinum particles on two-step, isothermal conversion of methane to higher hydrocarbons after correcting the effect of particle size. The activity of catalysts, that is, the total amount of methane converted to C2+ hydrocarbons and the distribution of C2～C6 products were investigated in the catalytic reaction for methane conversion over platinum catalysts supported on Y and Beta zeolites with different acidity. The results showed that the activity of catalyst increased with increasing support acidity and the selectivity to C2～C6 products varied with support acidity. Moreover, the distribution and reactivity of surface carbonaceous species (CHx) chemisorbed on the catalysts, generating from the methane decomposition at first step were characterized by temperature-programmed hydrogenation (TPH). The total amounts of CHx (Cα+Cβ) and the Cα species, most of which is known to give C2+ hydrocarbons on hydrogenation and which is main resource of C2+ hydrocarbon products increased when the acidity of support increased; The reactivity of surface carbon was enhanced on acidic support compared to neutral support. The changes of catalytic properties are due to electron deficient nature of platinum particles on acidic support from the interaction of metal and support.
Abstract: The technologies of desulfurization for vehicle fuel oil including hydrogen desulfurization, catalytic cracking desulfurization, adsorption desulfurization and oxidation desulfurization etc were reviewed. The oxidation desulfurization technique, involving oxidation and separation of sulfur-containing compounds, and its mechanism were especially presented. Due to the extra five 3d orbits of sulfur atom, it is easier for the sulfur-containing compounds to be oxidized than hydrocarbons. Sulfone could be obtained and separated from hydrocarbons through oxidation of the sulfur-containing compounds because of the improved polarity. Compared with other technologies, the oxidation desulfurization technique is predominant in investment, operation and hydrogen consumption. It meets the need of deep desulfurization, especially for dibenzothiophenes (DBTs) which are difficult to be treated by hydrogen desulfurization method.
Abstract: Based on the analysis of 15 raw coals and washed coals collected from Southwestern, the washing rate of arsenic, sulfur and ash from raw coals was studied. The average washing rate of arsenic in raw coal is 38%. Arsenic of raw coals is mainly associated with pyrite and sulfide. However, arsenic of some raw coals is mainly or wholly associated with organic matter and mineral enwrapped by organic matter. It is difficult to remove such part of arsenic and it will enrich in the washed coals. The results show that there is a little relationship between occurrence mode of arsenic associated with organic sulfur and rank of coal, but it is complicated with age of coal-bearing strata.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
