Abstract: The oxidative desulphurization process of coal with different metamorphism degrees treated by an air-steam mixture has been studied. It has been shown that the pyrite present in black coal and anthracite is oxidized with the sulphur dioxide formation, and the process chemical mechanism does not depend on the quality of organic matter. The medium-metamorphized coal, capable of turning into a plastic state and cake in the range of investigated temperatures (350~450 ℃), is desulphurized with the greatest difficulty. The chemical mechanism dealing with the transformations of pyritic sulphur present in brown coal differs from similar processes taking place in black coal and anthracite, because FeS2 is converted with hydrogen sulphide formation at desulphurization.
Abstract: Using a brown coal from Ximeng mine in Inner Mongolia as raw sample, 3% the carbonates of lithium, sodium or potassium were evenly mixed with raw coal and demineralized coal (the inherent mineral was removed by acid-washing). The effects of the minerals and the alkali carbonates added in raw coal on the formation of H2S and NH3 during temperature programmed pyrolysis was studied by a fixed-bed reactor and gas chromatography. The results show that the inherent mineral in Ximeng brown coal can restrain the formation and release of H2S and NH3 during pyrolysis. The temperature range of maximum H2S release from demineralized coal is same to that of raw coal because the organic structure of coal and the form of sulfur are not changed. But the behavior of NH3 is obviously changed in the different temperature range because the secondary reaction of HCN is also one of main sources for NH3 formation, which is affected by the pore structure change of coal demineralized by acid-washing. The alkali carbonates added have different effects on the formation of NH3 and H2S during pyrolysis. Except for K2CO3, the presence of alkali carbonates can prohibit the formation of H2S. They can promote the formation of NH3, except for Na2CO3 added in demineralized coal.
Abstract: An experimental study on the co-gasification property of coal char and biomass char with steam was performed in a thermogravimetric analyzer (TGA). The coal tested was Jincheng anthracite (JC), and the biomass was meat and bone meal (MBM). The chars were prepared by fast pyrolysis of coal and MBM individually. The morphology and composition of chars were analyzed by scanning electron microscope (SEM) equipped with an energy-dispersive X-ray analyzer (EDX). The results show that the co-gasification rate of JC/MBM chars mixture is higher than that of results expected from independent behavior. The high content of Ca and Na in MBM char plays a catalytic effect during co-gasification. After washing with acid, the reactivity of MBM char declines markedly. The gasification rate of coal char in JC/MBM chars mixture increases with increasing MBM char content in rang of 20%~80%.
Abstract: The effect of the calcium based organic compounds of the modified dolomite by acetate (MDA), calcium acetate (CA) and calcium propionate (CP) on the release of sulfur dioxide (SO2) and nitric oxide (NO) during LK-lignite combustion has been investigated on a horizontal tuber furnace. And also, the combustion characteristics of them have been studied in a thermogravimetric analyzer. Calcium based organic compound can suppress the release of SO2 and NO under the suitable conditions effectively. In the temperature range of 973~1 273 K, the calcium based organic can inhibit the release of SO2. But when the temperature grows higher, the inhibition effect of the calcium based organic reduces except CA. In the lower temperature range of 973~1 173 K, the calcium based organic promotes the release of NO, but when the temperature is higher than 1 173 K, CA and CP show the inhibition of NO obviously. The inhibition effect of SO2 and NO by calcium based organic generally increases with the increase of the mole ratio of calcium to sulfur (Ca/S). But when the Ca/S is between 2.0 and 2.5, MDA promotes the release of NO. With adding the calcium based organic to LK-lignite, when the Ca/S is 2.0, the ignition performance of LK-lignite improves, the ignition reduces 10~33 K, but its burn time is slightly lengthened.
Abstract: To investigate the fluidized characteristic of powder particle fluidized bed (PPFB), the experiment of cold model fluidized bed was carried out. The results show that fluidization of PPFB could be maintained when gas velocity is in an appropriate range. Pyrolysis and catalytic pyrolysis of pine biomass was also investigated using the PPFB. It was found that there is a rapid release zone for the volatile during biomass pyrolysis, about 92% of the volatile matter of pine is released at 723 K. The total yield of inorganic gas (IOG), hydrocarbon gas (HCG) and hydrocarbon liquid (HCL) is only 3.1%at 773 K. The yields of IOG, HCG and HCL increase with the increase of pyrolysis temperature. The total yields of IOG, HCG and HCL reach 58.7% at 1 173 K, and the pyrolysis product is almost CO. CoMo-B catalyst greatly promotes the secondary reactions of the primary products of catalytic hydropyrolysis. At 863 K the yield of light aromatic hydrocarbons (benzene, toluene, xylene and naphthalene) is 6.3%, which is 2 times higher than that by using SiO2 at 1 173 K.
Abstract: A thermogravimetric apparatus(TGA)was used to investigate the CO2-char gasification characteristics of petroleum coke, straw char, and the mixture using isothermal mode at the temperature ranging from 900 ℃ to 1 050 ℃. The rate of co-gasification increases with an increase of straw addition ratio. The results show that the order of reactivity of various prepared chars is as follows:straw char>deashing straw char>the mixture of petroleum coke and straw> the mixture of petroleum coke and straw char>the mixture of petroleum coke and deashing straw>the mixture of petroleum coke and deashing straw coke>petroleum coke. The co-gasification rate of the mixture of petroleum coke and straw char is higher than the rate sum of single petroleum coke and single straw, suggesting that there is a synergistic effect due to the co-gasification.
Abstract: The experiment on the non-catalytic steam gasification of bio-oil was carried out in a lab-scale fixed bed reactor. The influence of operating parameters such as the temperature and the mol ratio of steam to carbon (S/C) on the gas yield and composition was investigated. The results show that increasing temperature can enhance the conversion of bio-oil to syngas; the carbon conversion of bio-oil can be as high as 97.8% at 1 200 ℃, and the proportion of effective gas component (H2+CO) in the product gas is nearly 77% with a mol ratio of H2/CO=1.19. The mol ratio of H2/CO increases with an increase of S/C mol ratio, and reaches up to 3.69 at S/C=4. However, the addition of steam does not favor the increase of the composition of effective syngas. The product gas from steam gasification has a medium heating value.
Abstract: Methods of thermal cracking, partial oxidation and char bed conversion on tar destruction has been investigated by a two stage fixed-bed reactor, effects of fuel type, temperature, residence time, char particle size and char type on tar destruction are considered. The result indicates that tar conversion efficiency increase with the second stage reactor temperature increasing in all three kinds of conversion methods. Partial oxidation and char bed conversion is more effective in tar destruction compared to thermal cracking. Associated with partial oxidation and thermal cracking, char bed can get least tar yield. Three kinds of biomass tar yield in the experimental condition of 1 000 ℃ is: rice straw 0.43%, corn straw 0.61% and fir sawdust 1.15%, and the corresponding tar conversion efficiency is 98.28%, 97.23% and 96.29% respectively. Tar yield content of each conversion methods are decreasing with reactor temperature increase. It is really difficult to removal all tar completely in these experiments due to complex tar composition and experimental conditions. The results also show that biomass tar destruction feasibility are: rice straw > corn straw>fir sawdust, and on obvious diversity is obtained between different char species on tar destruction.
Abstract: A storage stability test was conducted on the bio-oil produced by fast pyrolysis of pine and corncob. The viscosity, water content and solids content of bio-oil increased after storage. However, there were no significant changes in the pH value, heating value and density of bio-oil. The quantitative analysis by GC/MS showed that the content of 1-hydroxy-2-propanone, acetic acid, and furfural were significant decreased. The content of 2-methoxy phenol, 4-methyl-2-methoxy-phenol, and 4-methyl-phenol increased. 13C NMR spectral analysis showed that the alkyl carbon and di-O-alkyl carbon content of bio-oil decreased after storage, while the content of aromatic and unsaturated carbon increased. Therefore, the aromaticity of bio-oil increased.
Abstract: Thermal weight loss curves of bio-oil/ethanol blends were determined by TG-DTA method in the oxygen atmosphere, kinetic parameters were calculated by both the Achar differential method and the Coats-Redfern integral method, and the properties of blend fuel pyrolysis chars were also tested. The thermogravimetric cures of bio-oil and its blends with ethanol can be divided into three steps: volatilization, secondary char formation, and char combustion. With the increasing of heating rate, the volatility and char combustibility of bio-oil turned better. With the increasing of ethanol content in the blend fuels, the active energies of volatilization and char combustion were both decreased first and then increased. The mass fraction of ethanol should not exceed 26%, otherwise the active energy of char combustion increased and the contained organic function groups in char decreased, which indicated higher stability and lower combustibility of the char.
Abstract: Effects of transition metals (La, Ce, Zr, Mn) on catalytic performance of double metal cyanide (DMC) catalysts for biodiesel synthesis were studied. The structure and performance of the catalysts were studied using XRD, FT-IR, ICP, BET et al. The experimental results showed that the DMC catalyst prepared by adding 1% of transition metal salts had higher activity. The catalyst with highest catalytic activity was prepared by adding 1% of La(NO3)3·nH2O. Under the conditions of methanol/oil mol ratio of 16∶1, catalyst amount of 2% and temperature of 160 ℃, a high yield (99.3%) of fatty acid methyl esters (FAME) was obtained within 7 h. The analytical results showed that adding 1% of transition metals did not change the molecular formula of Fe(II)-Zn double metal cyanide complex catalysts, while it improved particle dispersion, decreased particle size and increased surface area. This was the reason that transition metals promoted catalysts had higher activity.
Abstract: A theoretical study of the carbon atoms adsorption and diffusion on the surface and into the subsurface of Fe (111) is performed using DFT calculations. Before the carbon coverages up to 1 ML, the adsorbed carbons tend to exist in an isolated atomic state and cause a reconstruction of Fe (111) surface. The configurations of "mC2+nC" are energetically favorable on the Fe (111) surface at 1 ML ≤ θC ≤ 2 ML. At a higher coverage, complicated adsorbed patterns such as chains and islands are found, and we predict that these carbon islands can function as the nucleation center of the precipitation of graphite or carbon nanotubes on the Fe(111) surface. In the subsurface region, the carbon atom prefers the octahedral site. The barriers for diffusion on and into the Fe (111) surface and subsurface are 0.45 eV and 0.73 eV, respectively. Actually, C2 formation is thermodynamically favored, whereas C migration into the subsurface region is kinetically feasible.
Abstract: Ni-CaO-ZrO2 catalysts were prepared by co-precipitation under different conditions and used in the tri-reforming of methane; the influence of preparation conditions on methane conversion and catalytic stability was evaluated. The results indicated that the optimal parameters used to prepare Ni-CaO-ZrO2 catalysts include a calcination temperature of 973 K, a pH value of 10~12 for co-precipitation, and a reflux duration of 24 h. The catalyst prepared under the optimal conditions has a proper surface area and Ni-ZrO2 interaction; it exhibits promising catalytic activity and stability in methane tri-reforming, and the methane conversion exceeds 70% under a temperature of 973 K and atmospheric pressure.
Abstract: The experiment was conducted based on an industrial nickel-based catalyst. The effects of operating temperature, feed ratio, and operating pressure on the methanation and the factors for the catalyst deactivation were investigated. The results indicate that the formation rate of CH4 increases with operating temperature, pressure, and CO concentration. But the concentration of CO can not be excessive, because the activity of catalyst will gradually decrease if H2/CO≤3. The carbon deposit is found on the surface of deactivated catalyst by X-Ray Diffraction(XRD) and Energy Dispersive Spectrometer (EDS) analyses. It can be concluded that the deactivation of catalyst may be related to the surface carbon deposition. The BET surface area analysis shows that the rate of carbon deposition is related to the reaction temperature, and the higher the temperature, the faster the coking.
Abstract: Effects of reduction temperature on the properties and Fischer-Tropsch synthesis (FTS) performance of Fe-Mo catalyst were studied. Catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), Mssbauer effect spectroscopy (MES) and H2 temperature-programmed desorption (TPD). The characterization results indicate that the crystallite size of metallic iron, the reduction degree and the carbide content (in catalysts after reaction) monotonously increase with increasing reduction temperature, while the amount of H2 chemisorption on metallic iron sites show a maximum at reduction temperature at 350 ℃. FTS performance was tested in a fixed-bed reactor at 280 ℃, 1.5 MPa, 2 000 h-1 and syngas H2/CO= 2.0. It is found that the steady-state FTS activity and the heavy hydrocarbons (C5+) selectivity of the catalyst increase up to 350 ℃, and then decrease with further increasing reduction temperature. The catalyst redu at 350 ℃shows the optical FTS performance.
Abstract: Co3O4/CeO2 catalyst was prepared by co-precipitation-oxidation method. Adsorption of carbon monoxide and the co-adsorption of CO/O2 over Co3O4/CeO2 sample were investigated. In situ FT-IR analysis of the mechanism in CO oxidation was interpreted over Co3O4/CeO2 sample. Effects of the reaction conditions on the catalytic performance over Co3O4/CeO2 catalyst for carbon monoxide oxidation was investigated at humid and dry conditions. Results indicated that the addition of cerium to the cobalt oxide was beneficial for CO oxidation over Co3O4 at humid condition. The formation of carbonate species with reaction on Co3O4/CeO2 composite oxide slightly deactivated the catalyst. When the temperature was as low as 453 K, the dynamic equilibrium of formation and decomposition of carbonate species existed in Co3O4/CeO2 composite oxide catalyst. The carbonate species disappeared above 493 K. The strong interaction between CeO2 and Co3O4 may contribute to the excellent water resistance for low-temperature CO oxidation over Co3O4/CeO2 catalyst at humid condition.
Abstract: A series of HZSM-5 zeolite samples with different n(SiO2)/n(Al2O3) ratios and crystal sizes were hydrothermally synthesized and physically mixed with a methanol synthesis component (CuO-ZnO-Al2O3) to form hybrid catalysts. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the prepared hybrid catalysts in a pressurized fixed-bed under continuous flow conditions. The results indicated that the selectivity for CO2 decreased with the increase of n(SiO2)/n(Al2O3) ratios in HZSM-5 zeolite due to the decrease in the amount and strength of the acid sites, so the selectivity for DME was enhanced greatly. On the other hand, although the activity was not enhanced on the smaller sized HZSM-5 compared to the larger sized one, the selectivity for CO2 and hydrocarbons was decreased evidently.
Abstract: The oxidation efficiency of elemental mercury (Hg0) by fresh and 40 000 h SCR (Selective Catalytic Reduction) catalysts was studied with the help of simulated experiments under oxidation and SCR conditions, respectively. The structural and textural properties of the catalysts were characterized by various techniques, including N2 adsorption/desorption, SEM-EDS, FT-IR, and ion chromatography. It was found that the Hg0 oxidation efficiency over the 40 000 h catalyst is about 5%~20% lower than that of the fresh one under the oxidation condition (with HCl and O2), whereas it just decreases by about 5%~10% under the SCR condition (when NH3 and NO are added). The particles agglomeration phenomenon was observed for the 40 000 h catalyst, of which the BET, V content, and V5+ = O quantity decrease to some extent. The contents of the water-soluble ions (such as Na+, K+, NH4+, and SO42-) of the 40 000 h catalyst are higher than those of the fresh one. All these factors have a negative influence on the pore structure and active sites distribution over the 40 000 h catalyst, thereby reducing its Hg0 oxidation efficiency.
Abstract: V2O5-MoO3/ TiO2catalyst was prepared by sol-gel and impregnation method and modified with SiO2 to improve its alkali-resistant performance. The alkali poisoning was simulated by the immersion of the catalyst in alkali salt solution. The effect of SiO2 modification on the de-NOxactivity of V2O5-MoO3/ TiO2 catalyst in the selective catalytic reduction was investigated. BET, H2-TPR and NH3-TPD measurements indicated that the specific surface area, the redox ability (the reduction temperature is decreased by 10 ℃) and the acidity of the SiO2-modified V2O5-MoO3/TiO2catalyst are increased obviously. As a result, the alkali-resistant performance of V2O5-MoO3/ TiO2 catalyst was improved largely by the SiO2 modification.
Abstract: Combustion tests of a sludge coal water slurry (S-CWS) and Datong bituminous coal water slurry (Datong bituminous CWS) were performed in a 3.2 MW horizontal furnace to investigate the industrial application feasibility of S-CWS. The properties of ignition, combustion, slagging and pollutant emission were analyzed respectively. The results indicate that S-CWS with sludge mass ratio of 10% can be easily fired and combusted stably. With better burning and slagging properties than Datong bituminous CWS, S-CWS produces ample flame in uniform distribution. The addition of sludge results in high concentrations of sulfur dioxide and nitrogen oxides in flue gas, which can be relieved by adding desulfurizing agents in practice. Generally, it is satisfactory to burn S-CWS in the 3.2 MW furnace, offering a new feasible method of sludge disposal.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
