Abstract: Two kinds of residues, obtained from extraction of one weakly reductive coal, Shenfu-Dongsheng coal (SD), and one reductive coal, Pingshuo coal (PS), with sub- and supercritical water on a semi-continuous apparatus, were characterized by calorific value analysis and XPS analysis, and the combustion behaviors of residues were investigated by thermogravimetric analysis. The results show that the residues have higher calorific value than raw coal samples, and SD residue has higher calorific value than PS residue. C-C, C-O and pyridinic nitrogen, pyrrolic nitrogen are the dominant form of C, O and N on the surface of raw coal samples and their extraction residues. The combustion behaviors of extraction residues show that the SD residue is more reactive and more easily burned than PS residue.
Abstract: The pyrolysis characteristic of Shenhua coal and Shenhua direct liquefaction residue was studied using TG method. It is found that compared with coal, the weight loss and weight loss rate of residue are higher. The weight loss process of residue can be divided into three stages: the first is before the temperature of 173℃; the second is from 173℃ to 510℃, in which the higher weight loss is due to the pyrolysis and volatilization of oil, asphaltene and preasphaltene in residue; the third is after 510℃, in which the weight loss is continuing. Compared with the TG and DTG curve of THF extracted residue, it is found that the majority of weight loss of residue is due to the volatilization and pyrolysis of heavy oil; and compared with the TG and DTG curve of acid washed residue, it is noted the weight loss after 649℃ is mainly due to the decomposition of mineral matter and the cracking of organic compound.
Abstract: Catalytic steam gasification kinetics of Fujian Youxi anthracite using viscose liquor as catalyst was investigated in an isothermal thermo-gravimetric analyzer under ambient pressure. Coal conversions versus reaction time with different viscose liquor concentrations (0～12% NaOH) were measured at the temperature range from 850℃ to 950℃. The research shows that the viscose liquor can greatly improve the gasification rate and carbon conversion. The Loading Saturation Level (LSL) of the viscose liquor within the experimental conditions was also determined. The catalytic steam gasification reaction can be well fitted by a shrinking-core model(SCM) and the reaction rate constants are obtained. The kinetic analysis indicates that the catalytic gasification exhibits a prominent compensation effect between the activation energy and the pre-exponential factor. The kinetic equation including the compensation effects for the catalytic steam gasification of Fujian Youxi anthracite using viscose liquor as catalyst is presented.
Abstract: The occurrence mode and concentration of chlorine in liquid product including tar and water from co-pyrolysis of waste plastic (WP) and coal were studied. The effect of temperature, holding time, heating rate and gas flow on chlorine concentration in liquid product was examined. The result indicates that the addition of WP to coal in co-pyrolysis does not increase the organic chlorine compound in the liquid product. However, the tar yield increases, and the water yield decreases. The chlorine in water mainly exists as inorganic form (NH4Cl) and organic amine hydrochloride. There is no obvious C—Cl band in IR spectra of tar is observed. This indicates that the organic chlorine in tar is very little.
Abstract: The kinetics of CO2 gasification of a Chinese coal char during combined coal gasification and methane reforming have been studied using a thermo-gravimetric analyzer. The effect of methane on CO2 gasification of the char from 1173K to 1273K was examined. The results show that the coal char conversion rate increases with increasing temperature but decreases with increasing CH4 concentration. Carbon deposition, due to CH4 cracking, is reduced as temperature and carbon dioxide concentration increase. Two standard gas-solid reaction kinetic models, viz. the constant particle size (or progressiveconversion) model and the shrinking-core model, were applied to describe the overall carbon conversion of the char. It is found that the constant particle size model fits the experimental data better than the shrinking-core model. Accordingly the activation energy, reaction orders in CH4 and CO2 based on the constant particle size model are determined to be 312.4kJ/mol, -0.13 and 0.3, respectively. The presence of methane slows down the gasification rate of coal char.
Abstract: The ash fusion characteristics of Shenfu coal (A), sewage sludge (W1), modified sewage sludge (W2) and the mixture of coal and sewage sludge (AW1, AW2) were studied. The Shenfu coal with the addition of W1and W2 has lower fusibility temperature than coal and sludge. When 30.74g W1 ash is added to A ash, the ash fusion temperature reduces by 63℃ and reaches the lowest point, and when 51.23g W2 ash is added to A ash, the ash fusion temperature decreases by 82℃ and reaches the minimum. The analysis of the mineral matter of coal, sewage sludge and mixture was conducted by XRD diffractograms and the transformation of mineral matter in the mixture of AW1, AW2 at different temperatures was compared. The result shows that chloroapatite is formed and the transformation temperature of quartz, anhydrite, and hematite decreases when W1 is added to coal; while plenty of sodium in W2 and the transformation of sodiummineral matters in WA2 coalsewage sludge mixture at different temperatures are the main reasons for the lowering of ash fusion temperature.
Abstract: The effect of Ca-Fe-Ce series catalyst on the characteristics of anthracite combustion was investigated by thermo-gravimetric analysis. The results showed that there may be a synergetic effect among the components in the composite catalyst and the composite catalyst exhibits better performance than the single one for the anthracite combustion. The combustion characteristics of anthracite are affected by the dispersion of catalyst, heating rate and combustion atmosphere. The catalytic effect is enhanced by increasing the catalyst dispersion. The reduction degree of ignition temperature increases with the increase of heating rate. The ignition temperature decreases significantly with the increase of O2 concentration.
Abstract: The low temperature pyrolysis characteristics of major components of biomass were investigated using thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The TGA results show that thermal stability of major components of biomass was in descending order of cellulose > lignin > hemicellulose. The main pyrolysis temperature range of hemicellulose is at 210℃～320℃, whereas those of cellulose and lignin are 310℃～390℃ and 200℃～550℃ respectively. The Py-GC/MS was used for studying the effects of temperature on low temperature pyrolysis products of major components of biomass, which had different contribution to the volatiles. The degradation of hemicellulose generates acetic acid, 1-hydroxy-propanone and 1-hydroxy-2-butanone. The high yield of levoglucosan and anhydrocellobise is from pyrolysis of cellulose. Guaiacol is associated with degradation of the lignin.
Abstract: Tar in gas product from biomass gasification would block the downstream equipments and affact the gasifier operating. It is important to understand the tar evolving and cracking behavior in the fluidized bed gasifier. With peanut shell, rice straw and saw dust as raw materials, the gasification was carried out in a pilot scale fluidized bed gasifier at variant temperatures (750℃～850℃), air equivalence ratio(0.15～0.35) and catalyst addition. Simultaneously, tar component was analyzed using gas chromatograph with mass selective detector (GC-MS). It is observed that the tar content decreases obviously with temperature increasing, and the catalyst addition also displays a similar result, which is attributed to the cracking of heavy components in tar. Higher temperature and catalyst are effective for the controlling and removing of tar during biomass gasification.
Abstract: The production of biodiesel and nontoxic cottonseed meal by in-situ alkaline-catalyzed transesterification of the triglycerides (TG) in the cottonseed was investigated. The effect of the moisture content and particle size of cottonseed flour on the fatty acid methyl ester (FAME) content in the biodiesel and free gossypol (FG) content in the cottonseed meal was investigated. The reaction conditions including the molar ratio of methanol to oil, amount of alkaline catalyst used, and reaction temperature and time were optimized by the mono-factor and orthogonal tests. When the cottonseed flour with the particle size of less than 0.335mm and the moisture content of appreciate 1.92% is used, the FAME and FG contents achieve 97% and 0.031%, respectively, under the operation conditions of 30℃, methanol/oil mol ratio being 135, 0.10mol/L NaOH in methanol, and reaction for 3h. The FG content in the cottonseed meal obtained from in-situ alkaline-catalyzed transesterification is below the FAO standard.
Abstract: Macroporous Al2O3 was prepared through mixing Al2O3 sol with polystyrene(PS) microspheres, drying the suspension, calcining them to remove the PS template. The prepared Al2O3 supports were characterized by N2 adsorptiondesorption method and SEM. Macroporous Co-Mo/γ-Al2O3 catalysts were prepared by impregnating Co-Mo onto the Al2O3 supports. It was shown that BET surface area and pore volume of the PS template-prepared Al2O3 were 41.5m2/g and 0.35cm3/g, which were higher than those of controller catalyst, respectively. The catalytic performance of the prepared catalysts was tested in a high-pressure micro fixed-bed reactor using heavy Dagang coking gas oil as feedstock. The desulfurization degree and denitrification degree of the prepared macroporous catalyst, prepared using PS microspheres as template, were 12% and 22%, which were higher than those of controller catalyst.
Abstract: Titania-silica composite oxides (CTS) were prepared by the sol-gel method combined with supercritical CO2 drying, and then CTS was mixed with HY zeolite by different methods to obtain the composite supports (Y/CTS). The structure and acidity of the supports were further modified by P. Hydrotreating catalysts were prepared with Y/CTS as supports and Ni-W as active metal through the equal volume impregnation method. The effects of the mixed method and the content of HY zeolite in Y/CTS on the catalyst behavior were investigated. The results showed that the specific surface area and acidity of CTS can be adjusted by the addition of zeolite HY and the CTS structure retained with proper content of HY in Y/CTS; when the content of HY is more than 20%, the acidity amount of Y/CTS is higher than that of CTS, especially for the Bronsted acidity. P modification can adjust the acidity of the catalyst; the total acidity amount of the catalysts together with the fraction of Lewis acidity was increased. Shengli coker gas oil was used as feed stock to evaluate the hydrotreating performance of the catalysts. The results indicated that the hydrodesulferization (HDS) and hydrodenitrogenation (HDN) performance can be improved by using the mixed support Y/CTS with P modification.
Abstract: Molecular sieve Y was modified by a combination of hydrothermal treatment, dealuminization with oxalic acid, and hydrothermal crystallization in the presence of the surfactant cetyl trimethyl ammonium bromide (CTAB). The effects of CTAB amount used on the crystallinity, unit cell constant, SiO2/Al2O3 ratio, surface area and pore structure of the modified molecular sieve Y were investigated. NH3-TPD was employed to characterize the acidity. The results showed that after modification, the crystallinity and SiO2/Al2O3 ratio of the molecular sieve Y increase from 37.9% and 7.72 to 68.3% and 9.32, respectively. The unit cell constant a0 decreases from 2.4534nm to 2.4485nm. The pore volume of mesopores increases from 0.157mL/g to over 0.180mL/g. The total acid sites are reduced after the modification. Hydrocracking of vacuum gas oil (VGO) over the modified molecular sieve revealed that the conversion and yield of middle distillates is improved by 2.42% and 4.20%, respectively, compared with that over the industrial catalyst.
Abstract: A series of alumina-supported nickel molybdenum nitrides were prepared by temperature programmed reduction successfully. Their physic-chemical properties were determined by XRD, BET, H2-TPR and XPS, and their catalytic performance were evaluated through the hydrotreating reaction with thiophene or tetralin as feedstock. Based on the results of XRD, it can be concluded that the crystalline structure of supported nickel molybdenum nitrides was Ni2Mo3N. From H2-TPR analysis, it was found that the peak at low temperature range (200℃~400℃) was due to the reduction of surface oxygen on passivated nickel molybdenum nitrides. XPS results showed that there were Mo6+, Mo4+ and Moδ+ ions on the surface of supported nickel molybdenum nitrides, among which the content of Moδ+ ions was the most. Nickel molybdenum nitrides catalysts had good HDS activity and stability. But their HDA stability was not satisfied, especially with the presence of sulfur.
Abstract: Molybdenum phosphide catalyst was prepared via temperature-programmed reduction method, and the hydrodesulfurization catalytic activity was evaluated at atmosphere pressure with thiophene as model compound. Effects of preparation conditions, such as reduction temperature, P/Mo mol ratio and phosphor source on hydrodesulfurization activity were also investigated. Results indicate that the activity decreased with the increase of reduction temperature. And there was an optimal P/Mo mol ratio for preparing catalyst with high catalytic activity. MoP can form with different phosphor source, and the bulk structure of MoP catalyst is kept unchanged based XRD analysis in thiophene HDS condition.
Abstract: Platinum catalysts supported on carbon nanoparticles and other carbon materials were prepared. Their surface area, structure, morphology and particle size were characterized by nitrogen sorption, TEM and XRD. The activity of various catalysts for cyclohexane dehydrogenation was investigated under different reaction temperatures. The results showed that Pt particles were well dispersed on the surface of nanoparticles and the size distribution was in a narrow range; the Pt catalyst supported on the hollow carbon nanoparticles exhibited excellent activity and stability compared to the other carbon materials supported Pt catalysts.
Abstract: Ni/La2O3/Al2O3 catalysts were prepared by the methods of incipient wetness impregnation and evaporation. The influence of preparation method on the physicochemical properties and catalytic performance for the dry reforming of methane was investigated. The catalysts were characterized by X-ray diffraction (XRD), temperatureprogrammed reduction (H2-TPR), BET surface area, transmission electron microscopy (TEM), and thermogravimetry and differential scanning calorimetry (TG-DSC). The catalyst prepared by incipient wetness impregnation exhibited better Ni dispersion, more symmetrical distribution of particle diameter, larger specific surface area and more rational pore structure than that prepared by evaporation. As a result, the catalyst prepared by the incipient wetness impregnation possessed better resistance to Ni sintering and coking; its average coking rate was about 0.6737 mg/(gcat·h), only equivalent to 21% of the value of the catalyst prepared by evaporation. Moreover, the catalysts prepared by wetness impregnation exhibited much higher conversions of CH4 and CO2, higher selectivities of H2 and CO, as well as better stability for methane dry reforming than the catalyst prepared by evaporation.
Abstract: Supported metal catalysts for methanol synthesis from syngas was prepared by co-precipitation method and its sulfur resistance was studied . The experimental results show that Cu/ZnO exhibited the best methanol synthesis activity but deactivated quickly when sulfur-contaminated syngas was used. However, Pd/CeO2 showed stable methanol synthesis activity in the sulfur-contaminated syngas. The characterization results indicate that the active components of Cu/ZnO reacted with H2S in syngas and deactivated the methanol synthesis catalayst. CeO2 as support of Pd/CeO2 could first react with H2S in syngas and protected the metal active components, and further kept the stable methanol synthesis activity in the sulfur-contaminated syngas.
Abstract: Layered K1-2xMxTiNbO5(M = Mn, Ni) was prepared by ion-exchange of KTiNbO5 obtained by the solidstate method with Mn2+ and Ni2+. The crystal structure and optical property of the as-prepared K1-2xMxTiNbO5 were studied by using powder X-ray diffraction and ultraviolet (UV)-visible light diffuse reflection spectroscopy. The adsorption feature and photocatalytic oxidation activity of dimethyl sulfide (DMS) and ethyl mercaptan (EM) over the as-prepared K1-2xMxTiNbO5 were evaluated using infrared spectroscopy. K1-2xMxTiNbO5 showed a higher interval between sheets and a stronger absorbance to visible light than KTiNbO5. After ion-exchange with Mn2+ and Ni2+, the bandgap energy of KTiNbO5 was shifted from 3.35eV to 2.97eV and 2.45eV, respectively, whereas the weak interaction between K1-2xMxTiNbO5 and DMS/EM was little affected by the exchanged cation. The photocatalytic oxidation activity of K1-2xMxTiNbO5 for DMS or EM depended on the special cation. K1-2xMnxTiNbO5 emerged a photocatalytic activity only under ultra-light irradiation, which converted DMS to sulfoxide and sulfone, and EM to sulfonic acid. However, K1-2xNixTiNbO5 emerged the photocatalytic activity under visible light besides under ultra-light irradiation; EM was converted to sulfonic acid by visible irradiation, but to sulfate and carbonate by UV radiation.
Abstract: Adsorption experiments of vapor-phase elemental mercury were carried out by using modified bentonite-chitosan in a laboratoryscale fixed-bed reactor. VM3000 online mercury analyzer was applied to detect the inlet and outlet mercury (Hg0) concentrations. The characterizations of the sorbents were analyzed using the method of nitrogen (N2) adsorption/desorption, scanning electron microscope (SEM) and Fourier transform infra-red spectroscopy (FT-IR), etc.. It was observed that the porosity and specific surface area decreased after modifying. The FT-IR spectra demonstrated the iodine was found in the inlayer of bentonite, and the chemical reactions of iodine and sulfuric acid with the amide of chitosan occurred. The tests in the fixedbed reactor showed that the bentonite-supported chitosan exhibited lower mercury capture than raw bentonite, which indicated that the mechanism of gas phase mercury removal was different from that of ionic state mercury in liquid. Generally, the iodine-modified sorbents demonstrated higher mercury capture efficiency than raw sorbents, and the iodine-modified bentonite showed the best one. Mercury removal efficiency of bentonite supported by chitosan sorbents could be promoted from 85% to 100% when added appropriate amount of H2SO4，while that of iodine and sulfuric acid modified bentonite exhibited opposite tendency due to their absolutely different physicochemical properties.
K2O and K2SO4 are loaded on the catalyst V2O5(1%)/AC (V1/AC) by the method of wet immersing followed by drying. The effect of potassium compounds on the catalytic performance of V1/AC for the low temperature SCR of NO by NH3 was investigated. It was found that both K2O and K2SO4 as ultrafine particles loaded in V1/AC can cause the catalyst deactivation. The adsorption of NH3 on the catalyst, especially the portion of weakly adsorbed NH3, is inhibited remarkably by the loading of potassium compounds. The inhibition by K2SO4 is moderate, as compared with that by K2O; this is also in accordance with the extent of their effects on the catalytic activity. K2O brings on little change in the surface oxidizability of V1/AC, the catalyst deactivation by K2O is a result of the inhibition of NH3 adsorption. Comparatively, the loading of K2SO4 may enhance the possibility for the adsorbed NH3 being oxidized to NO by O2.
Abstract: The properties of pyrolysis and combustion for five different sewage sludges are studied by thermal gravimetric analysis at a heating rate of 10℃/min in the atomosphere of nitrogen and oxygen, respectively. The results show that both of the “anaerobic” wastewater treatment and the sludge anaerobic digestion make the organic compounds in sludge so complicated that the organic compounds decomposition and release temperature becomes higher during pyrolyzing, and the “aerobic + anaerobic” process makes the organic compounds in sludge more complicated than the “anaerobic +aerobic” process. There is no influence on the combustion process and the burnout point, but can make the combustion temperature of sludge higher. The thermal reaction mechanisms have been studied with šatava-šesták equation. It shows that the pyrolysis mechanism of these sludges is a process of volatile diffusion at first and then the chemical reaction function, while the combustion mechanism of them is a process of chemical reaction and diffusion function.
Abstract: ater adsorption on the Fetet1-terminated and Feoct2-terminated surfaces of Fe3O4(111) has been calculated at the level of density functional theory (GGA/PBE). On the Fetet1-terminated surface at 1/5 monolayer (ML), the molecular adsorption mode with a hydrogen bond and the heterolytically dissociative mode show the highest stability, whereas the hydronium-ion-like structure OH3+-OH becomes possible at 2/5 ML, followed by the hydrogen-bonded water aggregate. These results agree well with the available experimental observations. For Feoct2-terminated surface, the molecular water prefers to adsorb on the surface Feoct2 atom at 1/6 ML, whereas other adsorption modes become possible and may coexist at 1/3 ML. The Fetet1-terminated surface is more favorable than the Feoct2-terminated surface for water adsorption. The adsorption mechanism has been analyzed on the basis of the calculated local density of state.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
