Abstract: The ash fusion characteristics, particle-size distribution and gasification reactivity of Shenmu coal (SM) fine chars from ash agglomerate fluidized bed gasification were explored by ash fusion point analyzer, scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDX), and thermo-gravimetric analyzer. The results show that the decrease in basic ingredients (e.g. iron and calcium) and the increase in acidic ingredients make the ash fusion temperature (AFT) of SM fine chars lower than that of SM. There is a wide particle-size distribution in SM fine chars, which shows a significant multi-peak distribution, and a large difference of the elemental distribution in fine char particles with different sizes. The moisture content is lower and ash content is higher in fine power than that in SM, respectively. SM fine char has higher surface area than that of SM char, and relatively rich in meso-pores and macro-pores, which results in its higher gasification reactivity than SM char.
Abstract: Sulfur containing model compounds, tetradecyl mercaptan, dibutyl sulfide, phenyl sulfide, 2-methyl thiophene, benzothiophene and dibenzothiophene, were selected to investigate their sulfur removal and release behaviors during pyrolysis under inert atmosphere by thermo-gravimetric analyzer with mass spectrometer (TG-MS) and pyrolysis connected with gas chromatogram (Py-GC). It was found that the order of sulfur removal was tetradecyl mercaptan > dibutyl sulfide > 2-methyl thiophene > benzo thiophene > phenyl sulfide > dibenzothiophene. Except for phenylsulfide, this rule is contrary to the decomposition temperature order of the sulfur functional groups. SO2 evolution was detected by MS and GC for all those model compounds and COS evolution was also found except for phenylsulfide and dibenzothiophene; while H2S evolution was measured only for tetradecyl mercaptan, dibutyl sulfide and 2-methyl thiophene. However, SO2 content was much higher than H2S and COS in pyrolysis gas for each model compound, which may be caused by that indigenous hydrogen was much less than indigenous oxygen under inert atmosphere, when actived carbon was used as carrier. Thus, most of sulfur radicals can connect with indigenous oxygen and release in the form of SO2. For phenyl sulfide, benzothiophene and dibenzothiophene, as their indigenous hydrogen was not enough to react with sulfur radicals, no H2S was detected during pyrolysis under inert atmosphere, while SO2 was found and its content was very high in pyrolysis gas.
Abstract: Powder River Basin (PRB) coal, which accounts for over 40% of the coal consumed for power generation in the United States, was investigated for preparation of coal water slurry (CWS). The static stability and rheology of the CWS were characterized as a function of loading. The coal loading was varied from 30% to 50% and both ionic (sodium polystyrene sulphonate (PSS)) and nonionic (Triton X-100) surfactants were employed as additives. The addition of PSS to PRB slurries was found to yield poor static stability. On the other hand, Triton X-100 was found to be an effective surfactant, reducing the sedimentation by more than 50% compared to the one without surfactant in 45% CWS. Adding Triton X-100 reduces the viscosity of the CWS for coal loadings of 30% and 40%. Although the viscosities for coal loading of 42.5% and 45% are higher when Triton X-100 is added, the static stability is significantly better than for samples without surfactant. The highest coal loading for PRB slurry with acceptable viscosity for pumping is 42.5%.
Abstract: To investigate the morphology change of raw coal during fast pyrolysis and its effect on the coal char gasification reactivity, the specific surface area (SSA), average pore size, particle size distribution and morphology of Xinjiang Houxia coal and the fast pyrolysis coal char from the drop tube furnace were analyzed, and the chars were gasified with TGA (thermogravimetric analyzer). The results show that with the increase of pyrolysis temperature, the change of specific surface area (SSA) and average pore size has different trends. Besides fragmentation, swelling and agglomeration also occur in the fast pyrolysis process. The gasification of fragments is different, and the gasification stability of char under 1 200 ℃ is best.
Abstract: The pyrolysis process of raw (R-form) and acid-washed (H-form) Zhundong coal was investigated by temperature-programmed thermogravimetry, and the kinetic parameters were calculated using distributed activation energy model (DAEM). The results show that the pore structures of Zhundong coal keep abundant in pyrolysis. The presence of alkali and alkaline earth metals (AAEM) has no significant influence on the macromolecular network structure of Zhundong coal, but raises its equilibrium moisture content and release rate of volatiles during the secondary degasification stage. AAEM lowers release rate of volatiles during the main pyrolysis stage and final weight loss. The pyrolysis behavior of Zhundong coal could be described by the DAEM accurately within a wide range of temperature. The pyrolysis activation energy of R-form and H-form coal increases with increasing conversion. The activation energy of R-form coal is higher than that of H-form coal at the same conversion. The maximum value of activation energy distribution function of R-form and H-form coal is 261.85 and 264.51 kJ/mol, respectively. AAEM elevates the pyrolysis activation energy, makes its distribution more concentrated, and reduces the pyrolysis reactivity. The relationship between frequency factor and activation energy presents obvious kinetic compensation effect.
Abstract: The existing forms of sodium in Wucaiwan coal, a high sodium content coal from Zhundong area in Xinjiang Uygur Autonomous Regions, China, were determined by three-step-extraction method and by the analysis of microwave digestion and inductively coupled plasma atomic emission spectrometry (ICP-AES). The existing forms of sodium in treated samples and the chars were also determined. The transformation of sodium in the raw coal and the treated coals during pyrolysis was investigated. The results show that most of the sodium in Wucaiwan coal exists in the form of water-solution sodium, and the organically bound sodium exists mainly in the form of carboxylate. During pyrolysis, the release of water soluble sodium and ammonium-acetate soluble sodium from the coal samples mainly takes place in the temperature range of 650~850 ℃, and the release of total sodium gets to the largest value at 1 050 ℃ accompanied with the releasing of hydrochloric soluble sodium. However, most of the sodium in the treated coal chars exists in the form of insoluble type. The transformation of a part of water soluble sodium and hydrochloric soluble sodium in all samples into ammonium-acetate soluble sodium during pyrolysis at 450~650 ℃ can be observed.
Abstract: The effect of coal rank on coal catalytic hydrogasification was studied in a pressured fixed-bed reactor. The catalyst loading, methane release rate and gas composition were compared for coal samples with different ranks. The coal samples and residues were characterized by FT-IR and SEM. The results show that the reactivity of coal decreases with increasing rank of coal without catalyst loading, and the methane release rate from low rank coal is divided into two stages obviously. After adding catalyst, it is suggested that the reactivity of Shenfu bituminous coal performs the best, while that of Zunyi anthracite and Yunnan brown coal is poor. The results of SEM and FT-IR analysis show that the particle surface of high rank coal is smoother and the structure is more compact, and the strength of vibration intensity of aliphatic and aromatic structure increases with decreasing coal rank. All of the differences lead to the different reactivity of catalytic hydrogasification among the coal samples.
Abstract: Ash fusion characteristic parameters of 129 typical original ash samples were collected locally and abroad, which included coals, sewage sludge and blends of sewage sludge/coal. These data were used to study the effect of acidic oxides including SiO2, Al2O3, TiO2 and P2O5 on ash fusion temperatures (AFTs). The refractory minerals such as quartz, metakaolin, mullite and rutile formed by SiO2, Al2O3 and TiO2 improve the AFTs. The results show that Al2O3 is a main factor in determining AFTs. Furthermore, the non-metal oxides P2O5 has a significant correlation with the FT of sewage sludge and sewage sludge/coal blends and its increase can obviously reduce AFTs, which might be caused by the higher P2O5 content in sewage sludge.
Abstract: The effects of liquefying agent, catalyst, reaction temperature and time on the yield of bio-oil in microwave assisted liquefaction of wheat straw alkali lignin were investigated. And the liquefaction products were characterized by FT-IR, GC-MS and 1H-NMR. It is found that microwave irradiation greatly shortens liquefaction time with methanol as liquefying agent and ferric sulfate as catalyst, where the yield of bio-oil is up to 55.22% at the relatively low liquefaction temperature of 160 ℃ for 5 min. The structure of residual lignin after liquefaction exhibits very limited variation, indicating that the degraded lignin fragments have lower probability of recondensation, and residual lignin can be reused to improve the utilization rate of lignin. The identified liquefaction products are mainly monophenolic compounds, in which S, G and H type compounds account for 57.72%, 25.28% and 8.98%, respectively. The existence of the signals for β-O-4 and C-C bonds in the 1H-NMR spectra suggests that the bio-oils include a small amount of dimers and oligomers except for monophenolic compounds.
Abstract: A series of ionic liquids coupled with Raney Ni were used as dual functional catalysts in the hydrogenolysis reaction of glycerin to prepare propylene glycol. Effects of the ionic liquid structure on catalytic performance was studied. As a result, a solid heteropoly ionic liquid [HMIM]3PW12O40 with suitable acid strength was selected and characterized by FT-IR, 1H-NMR and TG. The composite catalyst [HMIM]3PW12O40/Raney Ni could give 83.3% glycerol conversion and 57.3% selectivity for 1,2-propanediol under the optimized conditions: 20 g 40% glycerol solution, 0.2 mmol [HMIM]3PW12O40 and 0.3 g Raney Ni dosage, 6 MPa hydrogen pressure (hydrogen to alcohol 2.37:1), 230 ℃, 11 h. What's more, the low cost composite catalyst could be prepared simply and recycled easily with good stability.
Abstract: The influence of calcination temperature on Ni/γ-Al2O3 reducing conditions and catalytic steam reforming of toluene was studied. The results indicate that the catalyst calcined at 700 ℃ showed good catalytic performance at reaction temperature of 680 ℃ and maintained a high catalytic activity, stability without pre-reduction and 99% of toluene conversion was obtained under optimum conditions. The catalysts were also characterized by BET, XRD, TG-DTG and other techniques before and after reaction. As the calcination temperature was raised, the interaction between nickel and carrier was gradually enhanced, surface area and total pore volume decreased, and amount of NiAl2O4 in the catalyst increased. These are considered the main reasons for the effect of calcination temperature on the catalyst reduction conditions. Finally, the structure of the catalyst calcined at 700 ℃ is further analyzed using TEM, XPS.
Abstract: NiW/Al2O3 catalysts for the hydrodenitrogenation of heavy oil were prepared by nickel-tungstate active metals located on Al2O3 with wetness impregnation. The effect of boric acid on the acidity and the effect of citric acid on the hydrogenation ability were studied. The results of NH3-TPD, HRTEM, H2-TPR and XPS showed that the addition of boric acid increased the proportion of strong and medium acid. The strong interaction between the support and metal has been weakened. Citric acid achieved moderate length of Ni-W-S active phases, increased the dispersion and the sulfidation degree of the metal on catalysts surface. NiW catalyst modified with boron acid and citric acid had outstanding HDN performance for Venezuela deasphalted oil, promoted the hydrogenation of aromatics and resin. It also had strong HDN abilities to basic and non-basic nitrogen compounds. The catalyst showed outstanding HDN performance of heavy oil.
Abstract: With Beta zeolite as the core crystals, core-shell Beta/MCM-22 composite zeolites with uniform morphology were synthesized by a two-step hydrothermal method. The composite zeolites were characterized by XRD, SEM, TEM, N2-adsorption and FT-IR. The results showed the composite zeolites exhibit uniform structured morphology; Beta and MCM-22 zeolites act as core and shell, respectively. The pore structure of Beta/MCM-22 composite zeolites was between those of MCM-22 and Beta zeolites. The amounts of medium acidic sites and brnsted acidic sites are increased markedly (CB/CL = 13.80) in the composite zeolites. The surface energy, Si-OH groups and surficial positive charges of Beta zeolites are enriched through Ar-H2 plasma surface treatment, which contributes to the formation of uniform core-shell Beta/MCM-22 composite zeolites.
Abstract: Supported perovskite-type catalysts La1-xCexCoO3/CeO2 (x = 0~0.3) were synthesized through complexing impregnation with citric acid and characterized by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), nitrogen adsorption, H2 temperature-programmed reduction (H2-TPR), and O2 temperature-programmed desorption (O2-TPD). The performance of NO catalytic oxidation and SO2 resistance were investigated in the article. The results showed that the catalytic activity of La1-xCexCoO3/CeO2 was closely related to the surface area and redox properties. Especially La0.8Ce0.2CoO3/CeO2 achieved 78% NO conversion at 300 ℃.The introduction of CeO2 as support simultaneously enhanced the low temperature activity and SO2 resistance.
Abstract: The Cu/γ-Al2O3 catalyst promoted with Ni was prepared by incipient wetness impregnation and used in the catalytic combustion of lean methane (3%) containing SO2 (0.01%) in a fixed bed reactor; the effect of Ni addition on the catalytic activity of Cu/γ-Al2O3 and stability against sulfur poisoning in lean methane combustion was investigated. The results showed that Cu/γ-Al2O3 catalyst is facilely poisoned by SO2 in the feed gas and its resistance against sulfur poisoning can be effectively improved through the addition of Ni as a promoter. The stability of Cu/γ-Al2O3 catalyst is increased with the increase of Ni content; over the Cu/γ-Al2O3 catalyst promoted by 10% Ni, the conversion of CH4 remains above 96% after reaction at 650 ℃ for 10 h. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and NH3 temperature-programmed desorption (NH3-TPD); the results illustrated that NiAl2O4 spinel is formed on the Ni-promoted Cu/γ-Al2O3 catalyst. Upon the formation of NiAl2O4 spinel, the surface Lewis acidity is reduced, and meanwhile, the adsorption of SO2 is weakened and the retention time of CO2 on the surface is reduced, all these may contribute to the high activity and stability against sulfur poisoning of the Ni-promoted Cu/γ-Al2O3 catalyst in lean methane combustion.
Abstract: The characteristics of agglomeration removal between wetting agent droplets and fine particles were investigated in an acoustic agglomeration chamber. A novel technique using wetting agents to promote the fine particle capture by acoustic agglomeration was presented. The experimental results show that the type of wetting agent has a significant effect on the acoustic agglomeration of fine particles. The particle stage removal efficiencies using JFC and FS-310 are similar to that using plain water droplets, but the removal efficiencies by SDS and Silanol w22 are much higher than that using water droplets. Fine particle removal efficiency in the acoustic field correlates well with the wettability of wetting agents, which decreases with increasing the relative contact angle of wetting agents. While the relative contact angle descends from 83° to 0°, the removal efficiency of fine particles with sound pressure level of 150 dB increases by about 18%. However, the removal efficiency of fine particle without acoustic effects only increases by about 5%. Higher sound pressure level can improve the particle removal efficiency that is extremely low when the sound pressure level is below 150 dB. However it can be improved with wetting agents addition to the atomization droplets. The capture efficiency can be increased by 25% with SDS adding than acoustic effect only under the sound pressure level of 130 dB. It indicates that the removal of fine particles is effectively improved by using wetting agents with acoustic wave agglomeration, and the high removal efficiency can be achieved at a low sound pressure level.
Abstract: Bentonite was modified with ammonium bromide to enhance its adsorption performance for the removal of elemental mercury. The adsorbents were characterized by N2 adsorption/desorption, X-ray diffraction (XRD), elemental analysis, and Fourier transform infrared spectroscopy (FT-IR); the adsorption test was carried out in a laboratory-scale fixed-bed reactor. The results showed that the performance of sodium bentonite in mercury removal is only slightly higher than that of calcium bentonite; however, its performance in mercury removal can be greatly enhanced through the modification with ammonium bromide. The mercury removal efficiency reaches 97.7% over the sodium bentonite modified with ammonium bromide (Br-Ben/Na). High temperature may promote the removal of Hg0 and the mercury removal efficiency remains higher than 90% over the 10% Br-Ben/Na adsorbent for a long time at 140 ℃, suggesting that chemical adsorption played a dominant role in the adsorption process. Through the modification with ammonium bromide, the sodium ions were replaced with the ammonium ions added to the bentonite layers; the specific surface area of the modified bentonite is decreased, whereas the average pore size is increased. During the calcination activation process, the ammonium ions may combine with bentonite within the layers, forming the adsorption active centers, which promotes the reaction between Br- and Hg0 and then enhance the adsorption performance of bentonite in the removal of mercury.
Abstract: The distribution characteristic of lead and cadmium in PM10 was investigated in a fluidized bed incinerator with kaolin as sorbent to control their emissions. The low pressure impactor (LPI) and atomic absorption spectrophotometer (AAS) were used to detect the size distribution of Pb and Cd in flue gas. The scanning electron microscope/X-ray diffraction/energy disperse spectroscopy (SEM/XRD/EDS) was used to observe the surface morphology and element distribution, respectively. More than 90% of particulate Pb and 85% of particulate Cd in flue gas are enriched in submicron particles. The volatilization of Pb is significantly higher than that of Cd. The reactions of Pb and Cd with kaolin powders can induce the eutectic-melt at high temperature, and its amount increases with the temperature rising. The melted kaolin particles conglutinate to larger particles which can shift the metals in flue gas from the fine to coarse particles. The addition of kaolin can effectively absorb submicron Pb and Cd. The best absorption efficiencies are up to 80% and 50% respectively. For submicron Pb absorption, the optimum incineration temperature is 950 ℃. For submicron Cd absorption, the reaction temperature is much higher; the obvious absorption process occurs until 1 000 ℃.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
