Abstract: The dynamic leaching experiments were carried out by different pH solutions in order to investigate the leaching behaviour of iodine in coal. Based on the contents of iodine in coal, residual and different leachates measured by inductively coupled plasma spectrometry (ICP-MS), the leaching rate (η) of coal and concentration of iodine (c) in leachate were calculated. The results show that the modes of occurrence and sites of iodine in coal, leaching time, and pH play important roles in controlling the leaching behavior of iodine. In limited time, the released iodine from coal increases with the rise of acidity of leaching solution, with leaching rates (η) of iodine from coal leached by pH 2.0 and pH 4.0 are 7.22% and 6.20%, respectively. However, the leaching rate of iodine in leachate (wx) leached by solution of pH 2.0 (1.92%) is less than that of pH 4.0 (5.42%). The average iodine concentration in leachate leached by pH 2.0 and pH 4.0 solution are 10.9μg/L in the first 40h and 10.6μg/L in the first 110h, respectively; there is little iodine in the leachates leached by pH 6.0 and pH 7.5 solution. Leached by acidic solution, the iodine occurred in little water-soluble and exchangeable, part of carbonate and Fe-Mn oxide forms which are on the surface of coal particles may be released firstly; and then the part of water-soluble and exchangeable iodine which are inside coal matrix come to be released.
Abstract: Distribution of oxygen-functional groups (carboxyl, alcohol-hydroxyl, phenol-hydroxyl, methoxyl and carbonyl) in 4 Chinese low-rank coals was evaluated based on chemical analysis. Concentration of carboxyl was quantitated by acetic acid calcium ion exchange method and the buffer (pH=8.3). The effect of analysis condition on the concentration of carboxyl and total acidity was studied. The results show that the reliable results are obtained in N2 atmosphere other than in air. The occurrence of carboxyl in coal is carboxylate. When quantitating the concentration of phenol-hydroxyl in the acid-washing brown coal with ion exchanged method, its concentration increases with increasing pH value. Concentration of carboxyl and hydroxyl account for 34.49% and 34.79%, respectively, in the total oxygen for the dry ash free basis brown coal. Different concentrations of carbonyl exist in the low-rank coals, but that of methoxyl is little.
Abstract: For understanding the influence of kinetic factors on coal slurry electrolysis, the voltage, temperature, and H2SO4 and Fe3+ concentration were studied. The samples of electrolyzed coal and fresh coal, and composition of the supernatant liquid after electrolysis were analyzed respectively by TGA and ICP. The results show that the parameters of voltage, temperature, Fe3+ and H2SO4 concentration have effect on the current density in the electrolysis. Furthermore, the relationship between the temperature and current density follows the Arrhenius equation. The apparent activation energy of the coal slurry electrolysis is 31.87 kJ/mol at 1 V voltage. TGA and ICP characterization prove that some metal elements in the coal are dissolved into the solution. The coal structure and ash content have obvious difference before and after the electrolysis.
Abstract: The pyrolysis of original coal(a lignite from Inner Mongolia), acid washing deashed coal and calcium nitrate loaded coal was investigated in a small fixed-bed reactor, and the gasification activity with steam for different chars was compared as well. The results show that both coal pyrolysis and gasification processes are affected by addition of calcium nitrate. Calcium nitrate can obviously promote the pyrolysis reaction and change the release regularity and cumulative quantity of main gaseous products(H2, CO2 and CO); while the alkaline-earth metal as a catalyst can reduce the gasification activation energy and promote the char gasification with steam.
Abstract: The gasification reactivity of raw coal, filter cake and the slag in demister from an industrial gasification plant was investigated with steam and carbon dioxide as the gasification agent. The initial structure and surface characteristic of the samples were analyzed by scanning electron microscope and adsorption apparatus. The results show that the gasification reactivity of the raw coal is better than that of the slag in demister, while the gasification reactivity of the slag is similar to or a bit better than that of filter cake, which is mainly attributed to the extraordinary difference of surface and internal structure of these three samples. As a result of different reaction mechanism with steam and CO2, the gasification reactivity of the samples with steam is about 3 times higher than that with CO2.
Abstract: The analysis of XRD indicates that slag is similar with minerals in the initial sediments. However, the proportion of bauxite Al2O3, hematite Fe2O3 has a big difference. The electric structure, elastic constants of Al2O3 and Fe2O3 were calculated using the ultra soft pseudo-potential plane-wave method based on the first-principles. The results show that from the structure of material, the accumulation mode of Al3+ and O2- in Al2O3 crystal is sparser than that of Fe3+ and O2- in Fe2O3, which is the reason for their different properties. For their chemical bonds in the direction of <100> and in tangential, Fe-O is more easy to deformate and fracture than Al-O, leading to Fe2O3 deposition in the clean water wall. For Fe2O3, tangential surface plays a key role for its deposit.
Abstract: The predominant mineral composition of Huadian oil shale and semi-cokes, including quartz, calcite and clays, was investigated in detail using XRD and SEM. The composition of semi-coke indicates that the minerals change slightly during the pyrolysis of oil shale. The quartz and feldspars remain the same. Few calcites are decomposed to form CaO which reacts with sulfur, resulted from decomposition of pyrite, to form CaS. The amorphous SiO2, generated from the decomposition of clays, tends to react with other metallic oxides to form relative low melting point mixture. This results in the molten vesicular microstructure in the semi-coke.
Abstract: The pyrolysis characteristics of black liquor solids (BLS) and three major organic components including alkali lignin (AL), polysaccharide (PLS) and lignin-carbohydrate complexes (LCC))were studied in a tubular furnace at 400~800℃ with 100℃ interval. The component distribution characteristics of the tar and gas were analyzed by gas chromatography with mass spectrometry (GC/MS) and gas chromatography (GC). The surface morphology and chemical structure groups of char were characterized by scanning electron microscopy (SEM) and Fourier Transforms Infrared Spectroscopy (FT-IR). The results show that the composition and distribution rules of pyrolysis products from BLS and its organic components pyrolysis are obviously different. AL, PLS and LCC have little effect on the yields of H2 and CO from BLS pyrolysis. The yield of CO2 from PLS pyrolysis is significantly higher than that from BLS, AL and LCC. Phenols and ethers in liquid products of BLS pyrolysis are mainly from the AL and LCC. Ketones and acids were resulted from AL, PLS, and LCC. The surface morphology of the BLS, AL, PLS, and LCC pyrolysis char is significant different. AL, PLS, and LCC affect each other in BLS pyrolysis process, and determine its pyrolysis characteristics together.
Abstract: The separation properties of sensitive bio-oil using molecular distillation technology were investigated under different distillation pressures. Crude bio-oil is divided into distillate fraction and residual fraction after the molecular distillation process. The yield of distillate fraction increases obviously with the decline of pressure, which achieves the highest value of 56.50% under 700Pa. Most of water is enriched in the distillate fraction while water in residual fractions is effectively removed; water content in the residual fraction under 700Pa is reduced to 4.20%. The distribution of some typical compounds, including acetic acid, phenol, furfural, levoglucosan, etc, under different distillation pressures was studied and the separation characteristic of these typical compounds was obtained; based on that, a separation factor model was proposed and a quantitative evaluation was made on the enrichment behaviors of 14 compounds in bio-oil.
Abstract: Catalytic cracking experiments were performed for bio-oil model compounds (acetic acid, guaiacol, n-heptane and hexamethylene, etc) using HZSM-5 molecular sieve catalyst at 550℃, aiming to study the reaction mechanism and catalyst properties. The results show that the main product for catalytic cracking of n-heptane and hexamethylene is aromatics (53% and 91%, respectively in area). Catalytic cracking reaction occurs more easily for those oxygen-free model compounds. The aromatics content increase effectively (from 12% to 90% in area) with increasing addition of catalyst for acetic acid. The guaiacol structure is quite complex and the catalyst mainly removes its methoxy group. Increasing the weight of catalyst could lead to aromatics formation more easily.
Abstract: The gasification of pine sawdust in an updraft gasifier was carried out at 400~900℃ to investigate the effect of temperature on the composition of the liquid products and their chemical origins. The liquid products were analyzed by using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography/mass spectrometry (GC/MS). The results showed that the primary liquid products are mainly composed of oxygenated compounds such as ketones, furans and guaiacols. The composition of the liquid products change largely with the gasification temperature: the guaiacols are transformed to phenolics at 400~500℃; the ketones and the furans are converted to phenolics at 500~600℃; the transformation of the phenolics to indenes and PAHs (polycyclic aromatic hydrocarbons) occurs at 600~700℃ and the phenolics to PAHs at 700~900℃; at 900℃, the liquid products were exclusively composed of larger PAHs.
Abstract: Eugenol, vanillic aldehyde and levoglucosan were selected as the model compounds of bio-oil heavy fractions for phenols, aldehydes and saccharides, respectively; their thermal degradation behaviors and pyrolysis kinetics were investigated by thermogravimetric and Fourier transform infrared spectrometer analyses (TG-FT-IR) under non-isothermal conditions. The results indicated that the hydroxylbenzenes exhibits the greatest tendency to decompose, followed by the aldehydes and carbohydrate. One stage thermal degradation is identified for eugenol and vanillic aldehyde, with the formation of water, CO2, CO, alkanes, alkenes, as well as small molecules of phenols and aromatic aldehydes. Levoglucosan pyrolysis proceeds slowly in two stages at medium-high temperature (180~370℃); the products are mainly composed of CO2, aldehydes, ketones, cyclic ethers, and a small amount of water and CO. As for the mixture of the model compounds, there are three stages in the pyrolysis process; the pyrolysis products evolved share the same compositions of three model samples besides the formation of some low molecular acetal polymers. Compared with the single model compounds, the interaction between the carbonyl groups and hydroxyl groups in the mixture of model compounds may produce polycondensates at high temperature (≥ 300℃), which makes a complete pyrolysis of the mixture more difficult. The saccharide should be the key substance that dominates the pyrolysis rate of heavy fractions. By fitting the dynamic profiles of each stage, kinetic parameters of thermal degradation were determined. For the pyrolysis of levoglucosan, the apparent activation energy and reaction order are 115.80kJ/mol and 0.5 (first stage) and 141.19kJ/mol 2/3 (second stage), respectively; for eugenol, the apparent activation energy is 42.29kJ/mol, with the reaction order of 0.7; for vanillic aldehyde, the apparent activation energy is 36.53kJ/mol, with the reaction order of 0.95; for the mixture of model compounds, the apparent activation energy and reaction order are 54.46kJ/mol and 1 (first stage) and 50.67kJ/mol 2/5 (second stage), respectively.
Abstract: CoMoS/γ-Al2O3 catalysts were prepared by ex-situ presulfiding method using ammonium thiosulfate as a sulfiding agent and characterized by XRD, N2 physisorption, NH3-TPD and XRF techniques. The catalytic performances were tested by hydrotreatment of jatropha oil in a fixed-bed reactor. The effects of sulfidity, reaction temperature, hydrogen pressure and reaction time on catalyst activity and catalytic product distributions were investigated. Reaction pathways for the hydrotreatment of jatropha oil were also discussed. The results showed that the CoMoS1/γ-Al2O3 catalyst with a sulfidity of 1 had the best hydrotreatment activity, showing 96.3% conversion of jatropha oil and 75.6% yield to the main components of C15~18n-alkanes at temperature 360℃ and hydrogen pressure 3 MPa. Its conversion was 36.9% higher than that of the non-sulfided CoMo/γ-Al2O3 catalyst at the same reaction conditions. It is worth noticing that both of the conversion of jatropha oil and the total oxygen-free compound of products could achieve 100% over CoMoS1/γ-Al2O3 at 420℃, 3 MPa. With the increase of sulfidity and reaction temperature or the decrease of hydrogen pressure, the hydrodecarboxylation and hydrodecarbonylation were enhanced.
Abstract: Direct conversion of cellulose into 5-hydroxymethylfurfural (HMF) was performed by using single or combined metal chloride catalysts in 1- ethyl-3-methylimidazolium chloride (Cl) ionic liquid. Our study demonstrated formation of 2-furyl hydroxymethyl ketone (FHMK), and furfural (FF) simultaneously with the formation of HMF. Various reaction parameters were addressed to optimize yields of furan derivatives produced from cellulose by varying reaction temperature, time, and the type of metal chloride catalyst. Catalytic reaction by using FeCl3 resulted in 59.9% total yield of furan derivatives (HMF, FHMK, and FF) from cellulose. CrCl3 was the most effective catalyst for selective conversion of cellulose into HMF (35.6%) with less concentrations of FHMK, and FF. Improving the yields of furans produced from cellulose could be achieved via reactions catalyzed by different combinations of two metal chlorides. Further optimization was carried out to produce total furans yield 75.9% by using FeCl3/CuCl2 combination. CrCl3/CuCl2 was the most selective combination to convert cellulose into HMF (39.9%) with total yield (63.8%) of furans produced from the reaction. The temperature and time of the catalytic reaction played an important role in cellulose conversion, and the yields of products. Increasing the reaction temperature could enhance the cellulose conversion and HMF yield for short reaction time intervals (5~20 min).
Abstract: Low-temperature oxidation of dimethyl ether (DME) to methyl formate (MF) with high selectivity was realized in a continuous flow fixed-bed reactor over the multifunctional MoO3-SnO2 catalysts designed and prepared intentionally. The effect of the preparation methods including mechanical mixing, co-precipitation and co-precipitation-impregnation on the catalyst activity was investigated. The results showed that the selectivity to MF reaches 94.1% at 160℃ over the catalyst prepared by co-precipitation-impregnation, with DME conversion of 33.9% and absence of COx in the products. The results of NH3-TPD, CO2-TPD and H2-TPR characterizations indicated that the catalysts prepared by various methods are also obviously different in the surface acidic, alkaline and redox properties. The results of Raman, XRD and TEM revealed that MoO3 structure and particle sizes have a significant influence on the catalyst activity; small particle size and oligomeric MoO3 may be responsible for the high activity of the MoO3-SnO2 catalysts from co-precipitation-impregnation in the selective oxidation of DME to MF at low temperature.
Abstract: NO reduction characteristics of reburning/advanced reburning using limestone modified by wood vinegar and calcium acetate, as well as selective non-catalytic reduction using ammonia, are investigated in a drop-tube system under O2/CO2 atmosphere. Results show that NO reduction efficiency of limestone modified by wood vinegar and calcium acetate through basic reburning increases first and then decreases with increasing temperature. The maximum NO reduction efficiency of 82.70% and 78.52% can be obtained at 1 323 K, respectively. High oxygen concentration is not conducive to NO reduction. The optimum reburning fuel fraction and residence time for basic reburning is 14%~17% and 0.8 s, respectively. The maximum NO reduction efficiency of selective non-catalytic reduction is 95.41% at 1 173 K in temperature window of 1 142~1 335 K. With increasing oxygen concentration, NO reduction efficiency declines continuously. The optimum [NH3]/[NO] molar ratio and residence time for selective non-catalytic reduction is 1.5 and 1.2 s, respectively NO reduction efficiency of reburning is significantly increased, while the reaction temperature window is obviously broaden when ammonia is injected into reburning zone at [NH3]/[NO] mol ratio of 0.75. The maximum NO reduction efficiency of limestone modified by wood vinegar and calcium acetate advanced reburning is 93.49% and 92.79% at 1 323 K, respectively.
Abstract: Sol-gel derived CuO/CuAl2O4, Co3O4/CoAl2O4 and Mn2O3/Al2O3 oxygen carriers were studied in a fluidized bed reactor under CO2 atmosphere, where the oxygen release characteristics under different temperatures were focused. The mechanism function and kinetics parameters in the oxygen release were obtained from the experimental data. In the process of oxygen release, the phases of CuO and CuAl2O4 performing as active components decompose to Cu2O and CuAlO2 with O2 generation. While, only Co3O4 and Mn2O3 can release oxygen in Co3O4/CoAl2O4 and Mn2O3/Al2O3 oxygen carriers, in which Co3O4 and Mn2O3 are respectively reduced to CoO and Mn3O4; and CoAl2O4 and Al2O3 perform as inert carrier. The kinetic analysis show that the oxygen release of three oxygen carriers can be described by the nucleation and nuclei growth model. This means that after O2 release the Cu-O bond (as an example) in the oxygen carrier is broken, generates Cu2O active sites diffusing away from the reduction centers, and comes together to form Cu2O clusters. The mechanism function G(x), the activation energy and the pre-exponential factor have different expressions or different values for different oxygen carriers. The activation energies in the oxygen release of CuO/CuAl2O4, Co3O4/CoAl2O4 and Mn2O3/Al2O3 oxygen carriers, are 226.37, 130.06 and 65.90 kJ/mol respectively; and the pre-exponential factors are 2.99×106 s-1, 4.96×103 s-1 and 27.37 s-1 respectively.
Abstract: Pyrolysis of sewage sludge was conducted in a single-mode microwave reactor and an electric-heated tube furnace, respectively. The effects of particle size, moisture content, pyrolysis temperature, and structure of microwave receptor on the yield and composition of hydrogen-rich gas were studied. The results indicate that the sludge particle size within 0~5.00 mm has no obvious effect on the mass distribution of pyrolysis products. However, H2 and CO concentrations increase with decreasing of particle size. When the size decreases from 2.50~5.00 mm to <0.45 mm, the H2 concentration increases from 31% to 34%, and that of CO increases from 17% to 22%. Both the sludge moisture content and the pyrolysis temperature have great influences on distribution of the pyrolysis products. Higher moisture content or pyrolysis temperature will lead to markedly higher concentrations of H2 and CO. When the sludge moisture content increases from 0 to 83%, H2 concentration increases from 32% to 42%, and CO concentration increases from 20% to 31%. Microwave absorber in powder phase can transform more volatile compounds into incondensable gas than that in fixed phase, and the concentrations of H2 and CO also increase slightly.
Abstract: The removal of hydrogen cyanide(HCN) using magnesium oxide(MgO)at various temperatures was investigated in the presented paper. The solid products were analysed by X-Ray Diffraction. The effects of temperature, mass fraction of MgO, initial volume fraction of HCN and residence time were discussed. The kinetic parameters of the reaction between HCN and MgO were obtained. Results show that MgO remarkably reacts with HCN through transforming the nitrogen in HCN into the solid product MgCN2 from 873 K. The removal efficiency of HCN increases with the increase of temperature, mass fraction of MgO and residual time in linear relation; but decreases with the initial volume fraction of HCN in negative power function relationship. The reaction order and apparent activation energy of the reaction between HCN and MgO are 0.72 and 32.2 kJ/mol respectively.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
