Abstract: Defferential Thermogravimetry, Thermogravimetry characteristics of single coal were studied and mathematical model for predicting combustion behavior of coal blends was established. The results show that DTG curve of single coal displays one peak and the peak temperature, tmax, relates to the fuel ratio F of the coal: tmax=68.86 ln（F）+512.2 (℃). The characteristics of DTG curves of coal blends can be obtained from that of single coal, which can be used to predict its combustion behavior. If the quality parameters of the coal blends meet the needs of the normative coal, its combustion behavior is good when Fmax/Fmin<3.20; it is middle when 3.205.70.
Abstract: The hydropyrolysis characteristics of Shenmu coal and its macerals were investigated using TG-151 thermobalance, and the evolved gases were on-line analyzed by Mass Spectroscopy. The results show that vitrinite has higher volatile yield, maximum weight loss rate and lower peak temperature. Vitrinite produces more C1～C4 lighter hydrocarbons and C6～C8 aromatic hydrocarbons than inertinite during hydropyrolysis, suggesting that vitrinite has higher aliphatic hydrogen content and lower aromaticity. Compared with inertinite, vitrinite has a higher water yield, which is consistent with that the vitrinite has higher phenolic-OH content. The difference in the evolved gases and water between pyrolysis and hydropyrolysis shows the effect of hydrogenation and hydrocracking during hydropyrolysis.
Abstract: Based on 8 active groups leading to spontaneous combustion of coal, a simple model of coal was developed to investigate the reaction mechanism of spontaneous combustion of coals at initial stage. Calculations about coal molecules model were carried out with Gaussian 03 (DFT-B3LYP) program. The results show that the oxidation reactions of 1, 3, 5, 6, 7, and 8 are exothermic, and except for reaction 2 and 4, other reactions have negative ΔGθ, which means that these reactions are spontaneous at room temperature. According to the calculations of activation energies of the reactions, it is concluded that six among the eight reactants tend to react with oxygen spontaneously at room temperature. Furthermore, the order of activity of these active groups deduced during experiments is roughly confirmed by the theoretical calculations. The reaction mechanism of low-temperature oxidation of coal at initial stage is also presented. The results well agree with those obtained by previous experiments.
Abstract: The pyrolysis characteristics of the coals and their blends in an inertia atmosphere were investigated using a thermo-gravimetric apparatus with a on-line infrared-spectrum analyzer. The influence of coal rank, blend ratio and heating rate on the pyrolysis of coal blends was examined. The experimental results show that the pyrolysis characteristics of coal blends are similar to that of single coal, but the yield of gas is not the simple addition of single coal's. Due to the interaction of different coals of the blends, there is a difference in the gas yield between coals and the blends. By investigating the infrared spectrogram, it is discovered that the low rank coal has an important role in the pyrolysis of the blends. The beginning pyrolysis temperature decreases and the yield of gas increases with increasing the proportion of low rank coal.
Abstract: Coal maceral concentrates of high purity were prepared from four different rank coals by Density Gradient Centrifugation method. The formation of HCN and NH3 during macerals pyrolysis was investigated in a tubular quartz reactor at the temperature of 600 ℃～900 ℃. The results show that HCN is mainly produced by the secondary thermal cracking of coal volatile. It also shows that the HCN yield increases with temperature and decreases with coal rank for vitrinite pyrolysis. For three macerals from Pingshuo gas coal, the yield of HCN is not only related to their volatile content but also associated with the nitrogen functional group in different macerals. Macerals withmore pyrrole-type nitrogen could release more HCN at lower temperature. As for the formation of NH3, besides the volatile thermal cracking, the char pyrolysis also plays a important role. The yield of NH3 depends on the probability of contact between nitrogen functional group and hydrogen radical. On the experiment conditions, the NH3 yield decreases with coal rank for vitrinite pyrolysis. The inertinite of less caking has more nitrogen converted to NH3 than vitrinite and liptinite. The yield of NH3 during pyrolysis at 800 ℃ is maximum with 11.8% for inertinite and 5.2% for liptinite.
Abstract: 1H and 13C NMR spectra of 6 petroleum asphaltenes, separated from different crude oils with n-hexane as solvent, were determined with a Bruker Avance DMX500 NMR spectrometer. And then a series of average chemical structural parameters were obtained. By combining the relative molecular weight and the elemental analysis results, the average molecular formula of the asphaltene units was calculated and the model molecules were evaluated. It is found that the asphaltene units are mainly composed of polycyclic aromatics linked with naphthene rings, side aliphatic chains, and O, N and S atoms. The asphaltene units are associated each other with the association number about from 4 to 6. These results provide an efficient structural description for the further study of petroleum asphaltenes at molecular level.
Abstract: The effect of heat treatment on the reactivity and microstructure of chars prepared from the vitrinites of two coals ( Yuxian lignite vitrinite (YXV) and Jianjiang bituminous coal vitrinite (JJV)) was investigated using X-ray diffraction(XRD) and Thermal Gravity Analysis(TGA). The results from TGA show that the reactivity of the chars from YXV and JJV decreases with the increase of heat treatment temperature. The reactivity of YXV char decreases quickly and significantly as the heat treatment time increases. However, after 60 min of heat treatment , it decreases slowly with time. The effect of heat treatment time on the reactivity of JJV char is slight. The results from XRD show that the microstructure of coal-char is determined by the intensity of heat treatment. When the heat treatment time is above 60 min, the structure of crystallites of YXV char prepared under 900℃ changes obviously and becomes more orderly. The aromatic layer stacking heights (Lc) of YXV char increase with the increase of heat treatment time when the heat treatment is conducted above 900℃. The effect of heat treatment time on Lc of JJV char is not significant, but under the heat treatment temperature of 1200℃, the crystalline of JJV char grows distinctly. There is a good parallel relationship between the crystalline growth and the deactivation of chars. It can be concluded that the growth of crystalline is the main reason for the deactivation of coal-char.
Abstract: The associative kinetics of one coal soluble constituent; pyridine insoluble (PI) and carbon disulfide-N-methyl-2-pyrrolidinone (CS2/NMP) mixed solvent soluble was investigated. It is clarified that the aggregation of PI molecules in NMP solution is a reaction controlled mechanism. A two-step kinetic process is provided, which are the formation of elemental aggregates and their clustering. The associative rate for the aggregation at different holding temperatures and solvents were determined, and the rate constants follow the Arrhenius equation. The activation energy of the aggregation of PI molecules in NMP solution is 73.3 kJ/mol and 21.6 kJ/mol for the first and the second step, respectively. The effect of temperature on the aggregation rate is remarkable, and the aggregation rate increases with increasing temperature. The aggregation rate of PI molecules in CS2/NMP mixed solvent is more quickly than that in NMP due to the higher diffusibility (mobility) of PI-1 molecules in the mixed solvent. The aggregation mechanism of PI molecules in solution was also discussed.
Abstract: Color development of jet fuel during storage is one of the indications of fuel instability, and these dark compounds in jet fuel may be detrimental to aviation engines while running. In this paper, dark jet fuel sample of Pingba RP-3 was taken from an underground storage tank. Adsorptive gum was separated by adsorbing fuel through neutral alumina with size of 100-200 mesh and eluting with acetic acid and distilled water. The gum sample was analyzed with organic element analyzer, gas chromatography combined with mass spectrometry (GC-MS), Pyrolysis-GC-MS and Fourier transform infrared (FT-IR) spectrometry to identify the colored compounds. In addition, simulative accelerated storage stresses under modified ASTM D4625 and ASTM D2274 were carried out to investigate the storage degradation properties of Pingba RP-3. The results show that the dark materials in Pingba RP-3 are concentrated in adsorptive gum. The predominant colored compounds in the gum are alkylated hydroxybenzene (some in polymerized form), and there are trace nitrogen heteroatomic compounds and no sulfur contained chemicals in the gum. The oxidation reaction plays an important role in the formation of colored components and adsorptive gum during storage. Alkylated hydroxybenzenes may be the main precursors of colored materials in Pingba RP-3.
Abstract: The sulfur-retention properties and microstructures of Shenmu coal ash are studied. It is found that the self-desulfurization efficiency of Shenmu coal with an initial molar ratio Ca/S of 1.45 dramatically decreases from 63.5% to 6.4%, when the furnace temperature increases from 800 ℃ to 1 200 ℃. The reason is that the active calcium (CaCO3 and CaO) content is 22.4% to give a sulfation product CaSO4 content of 18% in the combustion residue at 800 ℃. It is composed of many small particles with fine pores (specific surface area of 4.6 m2·g－1 and mean pore diameter of 14.2 nm), which form a loose cotton-like structure and provide large surface area for sulfation reaction. But none of the phases of CaCO3, CaO and CaSO4 is found in the coal ash at 1 200 ℃. It is composed of many large nonporous particles with smooth surfaces (specific surface area of 2 m2·g－1 and mean pore diameter of 5.5 nm), due to the high levels of sintering swell and melting.
Abstract: The catalysis mechanism of potassium salt in rapid pyrolysis of cellulose was studied in an infrared radiation bench scale reactor. The results show that potassium salt restrains the formation of aqueous oil, while enhances the formation of char and gas. On the basis of the distribution diagram of metallic salt by electron microscopy, and the content determination of metallic ion in aqueous oil and char, catalysis of potassium salt mainly occurs in solid phase during cellulose pyrolysis. It selectively catalyzes some reactions in the form of ion, and accelerates the cracking and splitting process of molecules. It causes a reduction of levoglucosan formation, and improves the production of hydroxyacetaldehyde, acetaldehyde and small molecule components including methanol, ketone or aldehyde.
Abstract: The studied insights into the average properties of binary system defined by Goossens et al. are incorporated into an Eulerian-Eulerian Computational Fluid Dynamics (CFD) model for simulating the hydrodynamics in a cold model of jetting fluidized-bed gasifiers. Some of the essential hydrodynamic parameters, including gas- and solid-velocity profiles, time-averaged voidage profiles, and jet penetration height, are investigated in this paper. These results show the CFD approach is an effective tool for predicting hydrodynamics in jetting fluidized beds with multi-component mixture.
Abstract: Numerical simulations of wood chips combustion process and emission were performed in order to predict the process of combustion and emission under different conditions using Navier-stokes equations, species transport equations, energy conservation equation, RNG k-εturbulent closure and the joint PDF equations, as well as Lagrangian-Eulerian two-way coupling and discrete transfer radiation model for discrete phase particles. The numerical simulation of the composition of CO, CO2 and O2 , velocity and temperature field can provide the basis to improve the efficiency of gasification and combustion of wood chips, and the efficiency of co-firing of municipal solid waste and wood chips. When the primary air is only supplied, the temperature at the exit of secondary combustion chamber is higher and the CO concentration in exhaust gas is higher, too. However, the rate of burnout is improved evidently with staged air-supply and smaller excess air coefficient.
Abstract: Effects of the pyrolysis chamber on the pressure distribution and the behavior of gas/solid flow in the standpipe of a CFB combined with coal pyrolysis reactor were studied. The riser column was 0.1m in diameter, 6m in height. And the standpipe was 0.044m in diameter, 3m in height. The rectangle pyrolysis chamber with cone-shaped distributing plates laid between the cyclone dipleg and the standpipe. The across section and the height of the chamber are 200mm×200mm and 0.77m respectively. The experiments showed that with the increase of the superficial gas velocity in the riser, Ur , the flow pattern in the standpipe was negative pressure difference flow whether the pyrolysis chamber was set up in the standpipe or not. And the negative pressure gradient decreased with Ur increasing. Solids in pyrolysis chamber must maintain a certain height, the flow pattern in the whole standpipe was negative pressure difference moving bed. If without pyrolysis chamber, the lean phase flow and the moving bed flow co-existed in the standpipe. And with the increase of Ur ,the equilibrium height of the solid in the standpipe was heightened. With circulating rate Gs increasing,the negative pressure gradient in the two type standpipes increased also. Without pyrolysis chamber, the increase of the circulating rate Gs would cause the equilibrium height of the solid in the standpipe declined. With Gs increasing the slip velocity in the standpipe was also increased.
Abstract: The effects of calcination temperature on the textural properties, reduction behavior and structural change during reduction and reaction of the Fe-Mn Fischer-Tropsch synthesis catalyst were studied. The F-T performances of the catalysts calcinated at different temperatures were investigated in a fixed-bed reactor under the conditions of H2/CO=2.0, 260 oC, 2.5 MPa and 1000h-1. The results of XRD and TPR indicated that the increase of calcination temperature could increase the crystallite size of α-Fe2O3 and decrease the specific surface area of the catalysts. Mn3+ ion gradually incorporates into the crystal lattice of α-Fe2O3, and the reduction peak of α-Mn2O3 completely disappeares at 700 oC. This incorporation results in the formation of the stable Fe2O3-Mn2O3 solid solution phase, which restrains the reduction of the catalyst. It is found that the catalysts with different calcination temperatures show high initial activity, while the increase of calcination temperature could improve the stability of F-T activity and shift hydrocarbon products to higher molecular weight. The catalyst calcinated at 600 oC shows relatively higher F-T activity and stability during the whole 200 h on stream of F-T run, which also gives the reasonable distribution of hydrocarbon and high selectivity of olefin and middle distilled cut.
Abstract: Catalysts with various Ru loading, 0.5%, 1%, 2%, 4% and 6%, for hydrogen generation by hydrolyzation of NaBH4 were prepared through replacement plating on nickel foam substrate. The kinetics of NaBH4 hydrolyzation in aqueous solution was a zero order reaction. The hydrogen generation rate became faster as Ru loading increased. When nickel foam surface was entirely covered with Ru, i.e. 6%, the catalyst became the most effective on decomposition of NaBH4. Comparing with the catalyst loaded on the ion exchanged resin beads, Ru loaded nickel foam was more stable and safer. NaBH4 decomposed more easily in 30% of aqueous solution than in 35% solution under the same catalyst loading. The addition of small amount of NaOH into the solution would promote the decomposition of NaBH4. Finally, energy calculation of NaBH4 aqueous solution was carried out and it was proved that a NaBH4-based hydrogen generator enables the target of hydrogen storage densities over 4% which may enable a micro proton exchange membrane fuel cell(µPEMFC) to be equal to or even better than Li-ion battery. A mobile phone powered by a prototype of a µPEMFC with such a small NaBH4-based H2 generator was demonstrated. This NaBH4 generator can be quickly refueled by simply filling the reservoir with fresh NaBH4 solution. Ru catalyst is reusable.
Abstract: The effects of oxidation and reduction pretreatments on the catalytic behaviors of Pd/CeO2-TiO2 catalyst for the low temperature oxidation of CO were investigated. The CeO2-TiO2 mixed oxides were prepared by sol-gel method. The H2-TPR measurements revealed that the reduction peak at 83 oC can be ascribed to the combined reduction of PdO and CeO2 on the support, and the interaction between Pd and the support becomes stronger with the increase of the reduction temperature, as convinced by the second cycle of the H2-TPR. The pretreatments of oxidation and reduction exhibit strong effects on the catalytic activity of Pd/CeO2-TiO2. The catalyst after high temperature oxidation at 500 oC and a successive reduction at low temperature at 150 oC gives the highest activity with the complete CO conversion at 48 oC in the 0.5% CO+1.6% O2+6.0%N2+Ar feedstock with a space velocity of 30,000 mL·h-1·g-1, which proved that an optimum interaction between Pd and the support is induced by such pretreatments. In the 0.6% CO+14.7% O2+55.3%N2+Ar flow, a complete conversion of CO reaches at ambient temperature and lasts for 12 h.
Abstract: The influence of precipitation method on the precursors of CuO/ZnO/Al2O3 catalysts were studied by XRD,TG-DTG and TPR techniques. The catalytic activity of the catalysts for methanol synthesis was tested using a differential fixed-bed reactor. It is found that the feeding method has strong influence on the Cu precursors in CuO/ZnO/Al2O3 catalyst. In case of base to salt, the initial precipitate was crystal Cu2(OH)3NO3; while in the case of co-current, the initial phase was mainly amorphous Cu2CO3(OH)2. The feed method has no effect on the initial phase composition and crystallinity of Zn-precursor and Zn5(CO3)2(OH)6 was the unique phase in the precursors. The phases of (Cu, Zn)2CO3(OH)2 and (Cu, Zn)5(CO3)2(OH)6 in the precursors of the catalyst were produced from the substitution of Cu2CO3(OH)2 (amorphous) and Zn5(CO3)2(OH)6. The activity of the catalyst was in the order of co-current>salt to base >base to salt.
Abstract: Fe-Al-P-O catalysts were prepared by sol-gel method. The physical and chemical characters and reactivity of the catalysts were studied by using techniques of IR, XRD, TEM, BET, TPR and micro-reactor. The experimental results revealed that Fe1/2Al1/2PO4 catalyst is a uniform compound of 10 nm particles FePO4 and AlPO4, in which FePO4 is highly-dispersed by AlPO4 and the activity of the lattice oxygen is higher than that in the single FePO4. The reactivity of Fe1/2Al1/2PO4 catalyst is obviously related with the feed composition. In case of propylene and oxygen only as the feed, the outcome is mainly acrolein. Addition of H2 into the feed stream leads to propylene oxide with some acrolein. Addition of H2O into the feed stream consisted of C3H6, H2 and O2, can effectively restrict the formation of by-product acrolein and increase the selectivity to propylene oxide. At a condition of 0.1MPa, 200℃, C3H6/O2/H2/H2O/N2(mol)=1:1:1:1:6 and space velocity of 1200 h-1, the propylene conversion of 8.9% and the propylene oxide selectivity of 81% can be obtained.
Abstract: Catalytic performances of hydrothermal dealuminated ZSM-5/Y composite zeolite in the cracking of Daqing VGO were studied in comparison with the mechanical mixture of ZSM-5 and Y zeolite. The results showed that, compared with mechanical mixture, the composite zeolite gives higher diesel and gas yields, especially higher gas olefins such as ethylene, propylene and isobutene, and lower gasoline yield. The difference of gasoline and diesel yields between the composite and mechanical mixture was elucidated from the structure of composite zeolite and shape-selective catalysis of ZSM-5. The agglomerate structure of the composite zeolite was in favor of gasoline cracking, and prevented the larger hydrocarbon molecular component from entering into it and cracking. The analysis of gas composition also supported the structural characteristic of composite zeolite.
Abstract: To get basic knowledge about the degradation of polyethylene (PE) to oils in supercritical water (SCW), the effects of reaction temperature, reaction time, water to PE ratio and water fill rate on the degradation of PE to oils were investigated in supercritical water with a 125mL autoclave. Reaction conditions were in the range of temperature 450℃~480℃, time 1min~30min, water/PE ratio 2/1~10/1 and water fill rate 25%~40%. The experiment results show that PE can be highly converted to liquid fuel and the temperature is the main factor effecting the decomposition of PE in SCW. The yield of oil decreases from 91.4% to 61.7% and that of gas increases from 1.9% to 27.7% with the increase of temperature from 450℃ to 480℃. A twofold increase of the yield of C7-11 hydrocarbons with the increase of reaction time from 10min to 30min is observed. The decomposition of PE is retarded to a certain extent due to the high water/PE ratio or high water fill rate. For increasing the productivity of the unit volume of reactor, keeping H2O/PE ratio at 2-4 is reasonable.
Abstract: The decomposition of NO was studied by using pulsed discharge corona plasma in nitrogen. The work focused on pulsed discharge corona plasma technique for NO decomposition and the effect of 13X pellets on the decomposition process. A quadrupole mass spectrometer was employed for online analysis of the reactants and products of NO plasma decomposition reaction. Experiments were conducted in a cylindrical corona reactor energized by repetitive high voltage pulses, which is a type of pin-plate reactor. All the experiments were operated under atmospheric pressure at temperature between 30oC~430oC. The gas flow rate was from 375 mL/min to 1333mL/min. When the reactor was filled with 13X pellets, the improvement of 13X on NO decomposition was studied and discussed. The effects of various parameters such as pulsed voltage magnitude, pulsed frequency, temperature of the 13X pellets, were discussed either. When the pulsed discharge condition is parallel and the temperature of 13X pellets is controlled at 200oC, the NO removal efficiency is 19.7%, much higher than 1.2% at 30oC. The highest removal efficiency can reach 35.9%.
Abstract: The goals of this paper are to establish the kinetic model of hydrothermal deactivation and the model of unit balance activity for FCC catalyst. At first, considering catalytic cracking reaction as a second-order reaction, the catalyst activity relating to hydrothermal deactivation is expressed as the ratio of cracking reaction rate for hydrothermal aged catalyst to cracking reaction rate for new catalyst. The kinetic model equations of hydrothermal deactivation for self-resistance are determined by considering that the catalyst hydrothermal deactivating is accompanied with the catalyst ultra-stabilization. Then, the hydrothermal deactivation kinetic models for self-resistance are developed through parameter estimations based on the steam aging experimental data of FCC catalyst. The results of statistics analysis show that first order deactivation kinetic model with second order self-resistance factor has higher precision. In other way, based on the flow property of complete stirred-tank reactor, the model of FCCU balance activity is developed. The study points out that the observed data of micro-reaction activity for FCCU balance catalyst is conformable with the calculated data with the model of unit balance activity. The prediction results of the balance activity model show that the micro-reaction activity of the FCCU balance catalyst increases quickly firstly, then increases slowly along with catalyst consumption. In the end, higher the regenerator temperature is or larger the catalyst content of regenerator is, the lower the micro-reaction activity of FCCU balance catalyst is.
Abstract: The advantages and disadvantages of a typical semi-dry flue gas desulfurization (FGD) method are analyzed and a novel semi-dry FGD method of simple and compact system with high efficiency is firstly put forward, named multi-fluid alkaline spray generator FGD method. The results show that the colliding activation efficiency between the sorbent particles and the spray water droplets in the prefixed alkaline spray generator may reach about 70%, which is significantly higher than the 25% colliding activation efficiency in in-duct injection FGD. And SO2 removal efficiency reaches 70%, higher than that of in-duct injection FGD at the same conditions. The study confirms it is a new simple compact and highly-efficient semi-dry FGD method.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
