Abstract: The circulating fluidized-bed gasification is a potential industrial technology for high efficient utilization of biomass in middle- and large-scaled power stations. A fast internally circulating fluidized-bed steam gasification technology has developed to obtain a high-grade synthesis gas without using pure O2. Some demonstration and/or commercial plants supported by European Union and its members are in underway. Computational fluid dynamics (CFD), an alternative method to the step-by-step experimental scale-up, is employed to simulate a laboratory-sized cold set-up in this paper. A modified particle-bed model has been attempted to investigate the fluid dynamic stability of gas-solid system in the bubbling fluidized bed. Superficial gas velocity is one of vital factors to influence the dynamic flow behaviour and pressure fluctuation. The bubble number and the size of the bubble increase with an increase of superficial gas velocity. Pressure fluctuation becomes higher with increasing inlet gas velocity. The higher gas velocity is and the greater time-averaged pressure drop is. Solid circulation is a single-cell pattern in the fast internally circulating fluidized bed. These results appear in good agreement with the experiments, which will be helpful for scaling up and designing the fast internally circulating fluidized-bed biomass gasifier.
Abstract: To achieve the aim of simultaneous SO2 and NOx removal from flue gas in a fix bed at the temperature of about 200 ℃, a novel catalyst of V2O5/activated coke (AC) was investigated. The experimental results show that the SO2 and NO removal activity of V2O5/AC at 200 ℃ is higher than that of pure AC. The effect of V2O5 loading was investigated as well. The SO2 capacity increases from 3% to 12% as the V2O5 loading increases from 0.5% to 9%, and the NO conversion shows a fall trend with increasing the V2O5 loadings. Results from the temperature programmed desportion (TPD) and FTIR reveal that H2SO4, ammonium-sulfate salt and VOSO4 are generated on the catalyst during SO2 and NO removal. The VOSO4 content would increase with the increase of V2O5 loading. The used V2O5/AC is regenerated at 300 ℃ by 5%NH3/Ar. It is found that the regeneration significantly increases the selective catalytic removal activity of NO, and improves the SO2 removal activity to a certain extent.
Abstract: Using ferric nitrate, zinc nitrate, ammonia liquor and binder as main starting materials, 6 zinc ferrite sorbents were prepared by co-precipitation method. The effect of binder on the spinel structure, sulfur capacity and desulfurization property of the sorbents were investigated. Desulfurization tests were carried out in a fixed-bed reactor. The structure, composition, specific surface area and pore volume of the sorbents were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and Gas adsorption meter. It is showed that ZnFe2O4 of spinel structure is not affected by different binders, and its particle diameter is in micron level. The sorbent with kaolinite as binder is the best one among the prepared sorbents for desulfurization, while the one with diatomite as binder is the worst. Different binders modify the textural properties of the sorbent, and then improve its reactivity. Furthermore, the reactivity and sulfur capacity of sorbents increase with an increase in its pore volume.
Abstract: The effects of minerals in coal on the emission of nitrogen and sulfur during coal combustion were experimentally investigated using thermogravimetric analyzer and X-ray photoelectron spectroscopy. The results show that the soluble minerals in coal, such as sulfate and carbonate, can enhance NO emission during coal combustion. When the minerals are removed from coal by HCl or HNO3, the emission of NO decreases and that of SO2 increases.
Abstract: An alumina supported β-Mo2N0.78 catalyst was synthesized via temperature-programmed nitriding reaction in N2-H2 mixture gases. The catalytic activity and selectivity for hydrodesulfurization(HDS) and hydrodenitrogenation(HDN) were studied by using benzothiophene(BT), dibenzothiophene(DBT) and quinoline as model compounds. The experimental results show that the HDS and HDN activity increases with the increasing of reaction temperature and pressure. There is little effect of increasing temperature on HDS selectivity of DBT because of its simultaneous improvement of two parallel desulfurization reactions, direct desulfurization and hydrogenation followed by desulfurization. On the other hand, high pressure favors the progress of the latter reaction. The HDS results of BT and DBT with the addition of quinoline indicate that the addition of N-containing molecule decreases the HDS activity of catalyst and restrains the reaction of hydrogenation followed by desulfurization. With the addition of S-containing molecule, not only the conversion of quinoline improves, but also the HDN activity obviously increases.
Abstract: The thermodynamic equilibrium calculations were performed to reveal the distributions of the trace elements (arsenic and selenium) during combustion of six Chinese coals. Actual coal compositions and combustion conditions were utilized in all simulations. The interaction between trace element and halogen and that between trace element and major minerals were considered during calculation. The rank and source of coals have significant effect on the distributions of arsenic. Arsenic mobility has varied dramatically when AsO(g) is ignored from the database. The constrained simulation results appear to more actually reflect the distribution of arsenic during coal combustion. The predicted modes of occurrence of selenium for the six coals are nearly identical.
Abstract: Pyrolysis and combustibility of coal and coal black liquor slurry were studied on the thermobalance. The characteristics of pyrolysis, combustion and carbon conversion are all obtained under different heating rates . It is shown that the combustion of coal black liquor slurry is catalyzed by sodium and its compound ,and also the organic matter composition plays a certain role in the burning of coal black liquor slurry. The activation energy of coal and coal black liquor slurry combustion at the heating rate of 20 ℃/min are 12.98 kJ/mol and 106.59 kJ/mol, respectively ，which indicates that the combustion characteristic of coal black liquor slurry is better than that of coal.
Abstract: The crystal compositions of self-desulfurization residues produced in a 1 025 t/h pulverized coal fired boiler using Shenmu coal were studied, which had the self-desulfurization efficiencies of 27%～33% at the full steam load. It is found by XRD analysis that the amorphous phase content is 91.2% and the CaCO3 content is 2.1% in the feed coal. In the fly ash derived from coal combustion at the full steam load, the vitreous phase content is 70.5% and the sulfation product CaSO4 content is 3.4%, while the CaCO3 and CaO contents are 4.7% and 2.2%, respectively. In the bottom ash, the albite content is 59.2% and the vitreous phase content is 25.7%, but none of CaSO4, CaCO3 and CaO phase is detected. With a decreaseof steam load of the boiler, the vitreous phase content in fly ash decreases but that in bottom ash increases.
Abstract: A simple viscosity method from Pal-Rhodes equation was described for the change of solution viscosity with time for one kind of coal soluble constituents PI-1, and the aggregation dimensions of the aggregates in solutions were calculated. The aggregation dimensions of PI-1 molecules in NMP and in CS2/NMP mixed solvent at 25 ℃ are 2.08 and 2.19, respectively, indicating the aggregation of PI-1 in solution is a reaction limited aggregation (RLA) mechanism. The aggregation dimension decreases with increasing temperature, suggesting the aggregation kinetic process may be converted to a diffusion limited aggregation (DLA) mechanism at higher temperature. The aggregation dimension of PI-1 aggregates is larger in NMP solution than that in CS2/NMP mixed solvent at high temperature (50 ℃), indicative of a lower aggregation kinetic process in NMP due to the lower diffusibility (mobility) of PI-1 molecules in NMP compared to that in CS2/NMP mixed solvent.
Abstract: The coprocessing of Shenfu coal and Shengli vacuum residue (SV) was studied using resonance agitation reactor. Coal conversion was investigated at 430 ℃, 46 ℃, 490 ℃, respectively, with reaction time from 3 min to 18 min. In this experiment system, the highest coal conversion of coprocessing is 48.56%; the optimum temperature and time are 460 ℃ and 15 min respectively. The reaction process can be divided into three stages, namely, rapid cracking hydrogenation, slow hydrogenation and polycondensation. Coal conversion is improved by adding anthracene into SVR, using hydrogenated SVR and benzene soluble fractions as solvent respectively. The hydrogenated SVR is not a good donor solvent for coal liquefaction. When benzene soluble fractions are used as solvent, the maximal coal conversion is 65.33% at 460 ℃ and 6 min.
Abstract: The temperature control of the flame zone plays an important role for synthesis gas preparation by the co-gasification of natural gas & coal. In this paper the factors affecting the temperature of the flame zone were investigated using a laboratory scale fixed bed reactor to simulate the industrial furnace for synthesis gas preparation. The inlet positions of methane and oxygen that make the flame minimum temperature were first investigated. Then the effects of the ratio of H2O/O2 and CH4/O2 in feedstock on the flame temperature were studied respectively. The experimental results show that the flame temperature is the lowest when the inlet position of CH4 and O2 is at the same level. Under this condition, the flame temperature decreases when the ratio of CH4/O2 and/or H2O/O2 is increased.
Abstract: The synthesis of methanol from CO2- rich syngas derived from biomass was carried out in a high pressure micro-reactor system. The effect of temperature, pressure and space velocity on space time yield (STY) and concentration of methanol was studied using a feed gas with H2 (52.5%), CO (21.5%), CO2 (22.8%) and N2 (3.2%). The results show that both STY and concentration of methanol increase with temperature and reaches maximum at 260 ℃, and then decreases. Higher pressure results in higher STY and concentration of methanol. STY increases and methanol concentration decreases under higher space velocity. The STY is 0.79 g·mL-1h-1 and methanol concentration is 96.2% under the conditions of 4 MPa, 260 ℃ and 5 280 h-1. Compared with the results of methanol synthesis using CO-rich industrial syngas, the STY and concentration of methanol decreases by 25.8% and 1.64% respectively. In order to improve efficiency of the whole system, off-gas can be used to produce electricity.
Abstract: The low-temperature pyrolysis of the mixture of nine typical components from municipal household garbage has been studied from 300 ℃ to 700 ℃ using an externally heated fixed-bed reactor with 200 mm diameter. The results indicate that with increasing pyrolysis temperature, the duration of pyrolysis reaction reduces, however, the total yield of pyrolysis gas and the maximum instantaneous yield increases. At the same time, the proportion of each gas component presents different variations with increasing temperature. At 600 ℃ the calorific value of the pyrolysis gas reaches the maximum, 15.13 MJ/m3, which meets the combustion standard for civil gas.
Abstract: TG and DTG experiments were carried out to study the pyrolysis kinetic behavior of the southern fir in various conditions. The atmosphere was changed from air to nitrogen or from nitrogen to air when the sample was heated to 200 ℃, 300 ℃, 400 ℃ and 500 ℃ respectively in a series of experiments. The aims of these experiments were to simulate the cases of local poor oxygen caused by fire and rich oxygen caused by the fresh airflow. The sample was first heated to 250 ℃, 300 ℃, 350 ℃, 400 ℃ and 450 ℃ respectively and then cooled to 50 ℃ and reheated to 700 ℃ in the atmosphere of air to simulate the repetitive burning after insufficient combustion in a fire. Through the experiments, the effects of pyrolysis conditions on the pyrolysis characteristics are understood. Based on the “First Order Two-stage Model”, the apparent activation energy and frequency factor of the samples in two temperature ranges of233.3 ℃～369.9 ℃ and 369.9 ℃～490.8 ℃ were obtained, which are 77.85 kJ·mol－1 and 1.95×106s－1, and 138.18 kJ·mol－1 and 4.84×109s－1, respectively.
Abstract: Reaction feed was prepared as follows: thiophene selected as model organosulfur compound in gasoline was dissolved in n-octane. The adsorption of thiophene in n-octane by activated carbon was investigated. The oxidant was 30% aqueous solution of hydrogen peroxide. Oxidative desulfurization with 30 % H2O2 in the presence of the activated carbon and formic acid was studied. Catalytic performance of the activated carbon and the effect of reaction conditions on oxidative removal of thiophene were investigated. Experimental results indicated that performic acid and hydroxyl radical produced in situ are coupled to oxidize model organosulfur compound with desulfurization ratio of over 85%. Catalytic performance of the combination of activated carbon and formic acid is higher than that of only formic acid. Formic acid concentration, activated carbon dosage and initial hydrogen peroxide concentration, reaction temperature affect the oxidative removal of thiophene.
Abstract: This paper illustrates the reaction pattern of the catalytic oxidative degradation of macromolecule in asphaltic sands. Parameters, including reaction time, catalyst system, that affect the change in the weight of organic phase and residual phase, were investigated in detail. It was found that ［(MoO2)( C5H7O2)2］ is an effective catalyst for the oxidative degradation of macromolecule in asphaltic sands. The reaction of the catalyzed degradation is related to the oxidant, H+ proton donator. In ［(MoO2)( C5H7O2)2］/t-BuOOH/ H3PO4 system, the conversion of asphaltene reaches 10.7% in organic phase and 20% in residual phase. The TLC-FID (Thin Layer Chromatography-Flame Ionization Detector) analysis indicates that the asphaltenes in asphaltic sands was transformed into resin and saturates. The yield of the degradation product is 11.7%.
Abstract: Environmental concerns have resulted in legislation which places limits on the sulfur content of gasoline. However, the major source of sulfur in the gasoline pool is fluidized catalytic cracking (FCC) naphtha which usually contributes 90% of the total in China. Most economic solutions would be to use an FCC catalyst additive which could reduce the sulfur content in the FCC naphtha in situ in the cracker itself. Here a group of additives have been studied. Based on support materials as alumina and magnesium oxide, cerium and iron were added by co-gel method. The additives were blended to 8 000×10－6 with a reference FCC-catalyst. By TG analysis, it was revealed that the additive with cerium and iron would strengthen the absorption of oxygen and turn it into the oxygen in the lattice and thus make SO2 easier to be oxidized and absorbed. The results show that the extent of sulfur removal of the additive with iron for the FCC flue gas can reach up to 85.7% in a simulating device while that the reduction of sulfur for the FCC product will reach 15.8% on the base of FCC-catalyst in fixed fluidizing bed (FFB) unit. It has also been shown that the additive has no effect on the catalyst activity and the FCC product distributions.
Abstract: A series of spherical micron-scale Fe-based catalysts, in which K and Cu promoters are incorporated respectively or simultaneously, are prepared by a combination method of continuous co-precipitation and spray drying technology. The textural properties, reduction performance, phase transformation in reduction and/or carbonization process are studied by means of low temperature N2 adsorption, MES, XRD, H2-TPR, CO-TPR and constant temperature reduction in H2, CO and syngas environment. The results indicate that the addition of K promoter can increase the surface area of Fe-based catalyst and iron species dispersion in catalyst, and reinforce the interaction between Fe2O3 and silica. The addition of Cu promoter improves the reduction of catalyst and the formation of Fe3O4 phase in H2 and syngas environment, but Cu promoter favors the formation and stabilization of a-Fe phase in CO environment. The addition of K promoter only will suppress the reduction and/or carbonization of catalyst in H2-containous environment, but the simultaneous addition of K and Cu promoters can apparently enhance the reduction and/or carbonization in H2, CO and syngas environment, which shows the synergic effect of Cu and K promoters.
Abstract: The critical properties of both binary and ternary mixtures involved in the toluene disproportionation were measured by using a high-pressure view cell with visual observation. Moreover, the critical properties of the ternary mixture were determined with the compositions representing reaction proceeding extent of toluene disproportionation. Based on that, toluene disproportionation over HZSM-5 catalysts under near critical and high temperature was comparatively studied. It was found that both the catalyst stability and the selectivity of para-xylene under near critical conditions in toluene disproportionation were higher than those under high temperature. The conversion of toluene increased with the temperature, but the selectivity of para-xylene decreased with the increase of temperature. The pressure has little effect on the selectivity of para-xylene at high temperature, but the conversion of toluene increased with the pressure.
Abstract: The coke deposition of various contents of nitrogen（sulphide）in toluene under different reaction pressures on hydrocracking catalyst has been obtained using accelerated aging experiment. Coke type and amount, acid strength distribution, pore structure, and dispersion of active metal of catalyst were measured by elemental analysis, FTIR, physical adsorption, XPS, and TG/DTG. The results showed that the amount of coke increases significantly when the content of pyridine or thiophene is higher than 0.1% or 0.6% in toluene. The coke deposited due to pyridine accumulated mainly in small pores (<6 nm), and it decreased the amount of acid center especially strong acid center. The coke deposited due to thiophene impenetrated into all the pores and some of them could form mechanical pore on catalyst surface. When the content of thiophene was higher than 0.6% in toluene, thiophene could enhance the active-metal sulphidation and weaken the coke production. Higher reaction pressure could make coke deposited less abruptly, decrease the loss of acid center, but result in the ratio of pseudo-graphite structure coke increasing relatively.
Abstract: The catalytic properties of Hβ, ZSM-5 zeolites and resin were compared in propylene hydration-etherification to produce diisopropyl ether (DIPE). The influence of promoters (both type and amount) on the Hβ zeolite pore structure, acidity and activity was examined. The results showed that the etherification property of Hβ is superior to ZSM-5; Hβ zeolite is suitable for etherification reaction, while resin has advantage in hydration reaction to product IPA. As the promoters of Hβ zeolite, TiO2, ZrO2, the alkaline-earth metal, the rare-earth elements and the VB elements can reduce the amount of Bronsted acid on Hβ zeolite, but increase the amount of Lewis acid on Hβ zeolite. Larger amounts of Lewis acid and total acid on Hβ zeolite can benefit the production of DIPE, but the pore structure has less influence on it. TiO2 can increase DIPE selectivity and yield, but contribute nothing to propylene conversion; ZrO2 can enhance DIPE selectivity, propylene conversion and DIPE yield，but can produce also more by-products such as acetone and C6; Adding the alkaline-earth metal, the rare-earth elements and the VB elements simultaneously can improve catalytic activity of Hβ zeolite obviously. At a suitable operating conditions (165 ℃, 7.0 MPa, n(water)/n(propylene) ratio of 0.5 and a LHSV of 0.5 h－1, the initial yield of the catalyst made by adding these elements could reach 39% at optimum conditions, and decreased by 3% after running for 1 000 h.
Abstract: Titanium silicalite (TS-1) was synthesized using small amount of TPAOH as template in the presence of Tween. The samples were characterized by XRD, FTIR, BET, UV-Vis, and SEM techniques. The XRD results showed that all the samples were fully crystallized and had characteristic MFI topological structure. FTIR spectroscopy for all the samples showed strong characteristic band at 960 cm－1, which indicated that titanium has incorporated into the silicalite framework. No band at 330 nm in the UV-Vis spectroscopy was observed, indicating no extra framework TiO2 (antase) existed in the samples prepared with Tween. The result of SEM showed that the crystal size of the TS-1 zeolite was more uniform. In the micelle solution with appropriate amount of Tween, the synergic effect between the surfactant and template molecules could enhance the interaction between template and silica and/or titanium species, also induced orientation reaction between them, which avoided the formation of anatase (TiO2). Such behavior also helped in reducing the concentration of excess template molecules required as space filler. Thus, the addition of Tween 20, Tween 40, Tween 60 and Tween 80 could not only greatly cut down the amount of TPAOH, but also improve the catalytic performance of TS-1 zeolite, and Tween 40 was found to be the most effective one among the four kinds of nonionic surfactants. It was conformed that when the molar ratio of Tween 40/TPAOH was 0.02, the conversion of hydrogen peroxide（x-H2O2） was 98.1% ,and the selectivity and yield of propene oxide（PO）could reach 96.1% and 94.3%, respectively.
Abstract: The thermal desorption behaviors of cyclopentane and cyclohexane in silicalite-1 was studied by using IGA and TG/DTG mehods. Only one thermal desorption course was observed in TG profiles when the initial adsorption loading of cyclopentane in silicalite-1 is lower than 4 m/uc. However, two obvious thermal desorption courses appeared in TG profiles when the initial adsorption loadings is higher than 4 m/uc. And there is an inflection at about 4 m/uc on the TG curves. The DTG profiles of cyclopentane exhibited two distinctive peaks separated each other. Only one thermal desorption course for cyclohexane in silicalite-1 appeared and the DTG profile show only one peak. From the thermal desorption profiles of cylopentane and cyclohexane, it can be seen that the desorption peaks move to higher temperature with the increase of the initial adsorption loadings. The temperature of desorption peak for cyclohexane is higher than that for cyclopentane at the same loading.
Abstract: Yima and American Pocahontas No. 3 coal samples were exhaustively extracted with carbon disulfide (CS2)/tetrahydrofuran mixed solvent and cyclohexanone, respectively. The residues after extraction were oxidized in 30% hydrogen peroxide aqueous solution at 40 ℃. Water-soluble and insoluble fractions were separated in the reaction mixture by filtration, and then extracted with benzene and CS2, respectively. The extraction solutions were analyzed with GC/MS. The results show that both water-soluble fractions from the two oxidized coal residues contain small amount of phenol. Oxygen-containing compounds and long-chain alkanes are detected in the extraction solution with CS2 from the water-insoluble fraction.
Abstract: The Zeta potential of thermal reaction samples of Middle East AR were studied by phase analysis light scattering (PALS) Zeta potential analyzer. The samples were confected into the mixture of n-heptane and toluene（1 g/1 g）, and the diluting ratio was (500 mL solvent) / (1 g sample). The results showed that the Zeta potential of ME-AR was –41.8 mV, and the Zeta potentials of 40 min and 100 min reaction samples were 26.9 mV and 31.8 mV. The result showed that the dielectric repulsive strength was not important to the colloidal stability of residue. Moreover, the diameters of colloidal granules of residue were increasing and the polydispersities were decreasing as the thermal reaction going on.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
