Abstract: The liquefaction properties and mechanism of Xiaolongtan (XLT) lignite were studied. On the basis of high content of water in lignite, the liquefaction behavior of XLT lignite under different atmospheres using water as solvent was preliminarily probed. The results show that XLT lignite has a good liquefaction activity, and its liquefaction conversion gets to 94.5% at 420℃, H2 atmosphere, and tetralin (THN) used as solvent. During coal liquefaction, the active H stabilizing free radicals formed during coal pyrolysis is mainly from hydrogen donor solvent. H2 gas has no hydrogenation activity, and it can not directly provide active H for coal liquefaction. When water is used as solvent instead of THN in liquefaction of XLT lignite, high liquefaction conversion occurs under CO atmosphere compared to H2 or N2 atmosphere. This suggests that the water gas shift reaction produces active H under CO atmosphere. The active H stabilizes the free radicals formed from coal pyrolysis to form lower molecular weight liquefaction products, and therefore, increasing liquefaction conversion. Because of the low primary pressure of CO in the experiment, the active H formed from the water gas shift reaction is limited. Thus, the liquefaction conversion of XLT lignite is not high when water is used as solvent. But our preliminary study shows that it is a new lignite liquefaction technology using water as solvent under CO atmosphere and has remarkable market value and utilization prospects.
Abstract: The effect of ferrum-based flux on the melting characteristics of coal ash in coal blends from the Liu-qiao No.2 coal mine in Wan-bei (AQ) was investigated. The change of the compositions of mineral under various temperatures before and after adding ferrum-based flux into AQ was studied by XRD and FT-IR. Results show that the presence of mullite formed over 1000℃ increases the melting point of coal-ash, leading to high melting temperature of AQ coal-ash. The coal ash fusion temperature will be decreased by adding ferrum-based flux. The eutectic mixtures such as fayalite and hercynite are easily formed between ferrum compounds under high temperature, which remarkably decreases the coal ash fusion temperature.
Abstract: The viscosity of slurry, which was made of Shenhua coal with bimodal distribution of particle size, was analyzed in detail. The effect of particle size ratio (λ) and different particle size volume fraction (ξ) were examined. An empirical correlation of slurry viscosity based on the experiment results was proposed. The results show that preparation the coal slurry with bimodal distribution of particle size can effectively reduce the viscosity of slurry and improve its volume fraction (Φ). With the same volume fraction, the viscosity of slurry rapidly declines as increasing particle size ratio. The viscosity of slurry is the smallest when the volume fraction of small particle is 35%. The maximum volume fraction calculated using Ouchiyama model is in agreement with the experimental values. The intrinsic viscosity [μ] keeps at constant value. If the effects of λ and ξ are fully taken into account in the maximum volume fractionΦm, the correlation of viscosity for single-peak distributed slurry could be used to predict that of bimodal distributed slurry.
Abstract: In order to get the vapor-liquid equilibrium constants under the real liquefaction conditions, the data from the fractions of coal liquefied distillation oil and different gas, such as H2 and C2H6, were combined together to establish the coal liquefied oil flash distillation system through the process simulation software Aspen Plus. By using the flash-distillation system, the vapor-liquid equilibrium composition and distribution were calculated at reaction temperature and pressure. Also the rules of equilibrium constant vary with the temperature (623.15K~723.15K) and pressure (10MPa~21MPa) were explored. Furthermore, the parameters of deducing hydrocarbon equilibrium equation at high pressure were regressed. And the two variable vapor-liquid equilibrium equation specified for the Shenhua coal liquefied oil was established.
Abstract: Methane cracking over a lignite char was studied in a fixed bed reactor. The experiments were performed at temperature range from 1123K to 1273K and atmospheric pressure. The total flow rate was 250mL/min with methane concentrations of 10%, 15% and 20%, respectively. The lignite char shows a significant catalytic activity on methane cracking. The maximum conversion of methane of 99.5% is achieved at 1273K in the initial stage. However, the methane conversion decreases with reaction time due to deactivation of the lignite char by carbon deposition on surface of the char. The results also show that higher initial methane conversion is achieved at higher temperature. Furthermore, the higher the methane concentration, the lower the methane conversion and the faster the deactivation of the char occurs. During the reaction the carbon deposits on the surface of the char.The spent char shows a lower surface area, total pore and micropore volumes, and larger pore diameters than those of the fresh char. This observation seems to suggest that the carbon deposition takes place in the pores, especially in the micropores of the char, leading to blockage of the pores for continuing catalytic cracking of methane.
Abstract: A new method of investigating catalytic combustion characteristics of pulverized coal was introduced using synthetical thermal analyzer, that is, the referenced DTA. Ignition temperatures of anthracite with K2CO3, Fe2O3, CaCO3 and CeO2 addition were 319℃, 410℃, 400℃ and 405℃ respectively determined by the referenced DTA. The ignition temperatures decreased by catalysts were observed directly from the reference DTA curves. In addition, variations of heat release during pulverized coal combustion were calculated by the referenced DTA curves. The heat releases of anthracite combustion increased by 340.2J/g, 352.8J/g, 348.6J/g and 264.6J/g, respectively, with K2CO3、Fe2O3、CaCO3 and CeO2 addition. The above results are accordance with those from conventional DTA experiment. However, the referenced DTA is more effective and direct to show catalytic combustion characteristics of pulverized coal.
Abstract: The CO2 gasification reactivity and structure of rice straw chars and the effects of pyrolysis temperature and heating rate were studied. Char samples were prepared by pyrolysis at 550℃~950℃ with heating rates from 0.1K/s to 500K/s in three different pyrolyzing reactors. The CO2 gasification reactivity of char was determined by means of isothermal thermo-gravimetric analysis on a STA409 TGA. Results show that the gasification reactivity of char increases with the decreasing of pyrolysis temperature and with the increasing of heating rate. It is found that the gasification reactivity of char increases when the gasification temperature rises from 850℃ to 950℃. Scanning electron microscopy (SEM) analysis was employed to determine the impact of pyrolysis heating rate on the char structure. It is indicated that the char pyrolyzed at 500K/s is of more cavities than the char pyrolyzed at 0.1K/s. Moreover, the kinetic parameters based on the mixed reaction model were obtained.
Abstract: The pyrolysis and combustion characteristics of a city swage sludge were studied by analysing the TG, DTG and DSC curves from a thermogravimetry. The combustion and pyrolysis TG curves are similar before 250℃, suggesting that the loss rate of weight is controlled mainly by the decomposition of organic matter, and the action of combustion is less. The DTG curve of combustion presents a “W” shape peak, the first peak is in a good agreement with the pyrolysis DTG curve. The weight loss rate has a rapid acceleration after 410℃. Based on the Coats-Redfern integral method, some reaction models are tested to fit the combustion process, and the results show that the burning process with two DTG peaks has a complicated mechanism. It can be concluded that the volatile burning in the initial combustion stage is controlled by the chemical reaction rate, while with the rising of temperature the combustion rate of the residual volatile and fixed carbon is controlled gradually by the diffusion. According to the mechanism, a four-parallel reactions model is brought out to simulate the burning process, which better fits the experimental data.
Abstract: A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C17~22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%~95% α-olefins. Other intermediates were produced in the same way by using commercial C20 α-olefin instead of C17~22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.
Abstract: The factors affecting FCC naphtha olefin upgrading, such as the preheating temperature, regenerated catalyst temperature, mix temperature and catalyst to oil ratio in the mix zone were investigated in a continuous pilot riser-type FCC unit. The results showed that low regenerated catalyst temperature, low mix temperature and low catalyst to oil ratio can reduce the yield of coke and fuel gas, but impair the FCC naphtha upgrading effectiveness. The temperature of catalyst regenerated is the main factor that determines the yield of coke and dry gas, while the effectiveness of the FCC naphtha upgrading is mainly dependent on the ratio of catalyst to oil. The decrease of regenerated catalyst temperature, catalyst to oil ratio and mix temperature can reduce the conversion of olefins and the content of aromatics and i-paraffins; while the increase of the preheating temperature give the reverse effect. Therefore, the optimal conditions in the mix zone were high preheating temperature and low regenerated catalyst temperature with a proper reaction temperature and a proper ratio of catalyst to oil.
Abstract: Mesoporous HPW/SiO2 modified with Ag species was used as the catalyst for the oxidative desulfurization of both model and real diesel oils. Three model diesel oils were prepared by using petroleum ether, benzene, and octene, respectively, as solvent and with dibenzothiophene (DBT) as the objective sulfur compound. The catalyst with a molar ratio of Ag to HPW being 2 (Ag2-HPW/SiO2) exhibits the highest catalytic activity; however, the catalytic activity decreases with further increase in Ag content. The results of nitrogen adsorption-desorption, X-ray diffraction, UV-vis, and energy dispersive spectroscopy show that isolated Ag+ ion is located on the modified catalyst. The modification of HPW/SiO2 with Ag species may combine the selective absorption capacity of Ag+ for sulfur compounds with the catalytic activity of HPW, which is helpful to enhance the selective oxidative desulfurization. During the desulfurization process, the sulfur compounds were first selectively adsorbed on the catalyst surface by π complexation between Ag+ and sulfur compounds, which could increase the probability of collision between sulfur compounds and catalytic active sites and then accelerate the oxidation reaction. The sulfur content in the real diesel oil can be reduced to 228×10-6 from the original 1800×10-6 over Ag2-HPW/SiO2; the desulfurization amount is 4.6% higher than that over the unmodified HPW/SiO2. In addition, the Ag-modified catalyst shows excellent reusability; after three reaction cycles, the desulfurization ratio of Ag2-HPW/SiO2 is only slightly lower than that of the fresh catalyst.
Abstract: H2O2 and trichloroacetic acid were used in the catalytic oxidative desulfurization and the sulfon oxides produced were extracted from diesel with the polar solvent. The effects of technical parameters such as the volume ratio of oxidant to oil, the dosage of organic acid, the reaction temperature and the reaction time were studied. Furthermore, the power ultrasound was introduced to the process. The effects of ultrasonic frequency, intensity and time on the desulfurization were investigated as well. The optimal operating conditions are determined. The removal efficiency of sulfur compounds is up to 97.5% and the yield of diesel can reach 94.0%.
Abstract: NiMoP/Al2O3 hydrotreating catalysts with different phosphorus contents were prepared by impregnating NiMoP aqueous solution into γ-Al2O3. The hydrodesulfurization （HDS）and hydrodenitrogenation (HDN) performances of the catalysts were evaluated using the model compounds dibenzothiophene and quinoline methylbenzene. The results show that the HDS and HDN performances of the catalysts can be improved by adding moderate quantities of phosphorus in the catalysts, and its performance can be decreased markedly when the catalysts have high phosphorus content. The catalysts were investigated by means of XRD and high-resolution transmission electron microscopy (HRTEM) to get a better understanding of the nature of active. The results of XRD and HRTEM characterizations indicate that the number of stacked layers of active component MoS2 increases with the increase of the phosphorus content. Because the interaction between active component and carrier γ-Al2O3 is weakened by adding phosphorus into the catalysts, the relative content of type-II“Ni-Mo-S”phase is increased.
Abstract: The catalyst nickel supported on active carbon (Ni/C) was prepared by isometric wetness impregnation method and characterized by BET and XRD measurement. The effects of preparation conditions on the performance of the Ni/C catalyst for vapor phase carbonylation of ethanol were investigated. The results showed that the catalytic performance of Ni/C is strongly influenced by the preparation conditions; the optimum preparation conditions are: Ni loading of 5%, pretreatment of active carbon with water, pH value of impregnation solution within the range from 8.0 to 9.0, calcination temperature of 450℃, and H2 reduction temperature of 400℃. Over the catalyst prepared under the optimum conditions, the conversion of ethanol and the selectivity to propionic acid reach 96.14% and 95.71%, respectively.
Abstract: A series of Cr/SiO2-G catalysts with different chromium contents were prepared by sol-gel method using chromium nitrate as the chromium source and tetraethyl orthosilicate (TEOS) as the silica source. The catalysts were characterized by XRD, BET, SEM and TPR. The catalytic performances of Cr/SiO2-G for the oxidative dehydrogenation of ethane to ethylene with CO2 were evaluated in a fixed-bed micro-reactor. XRD results indicated that Cr species were presented in Cr2O3 phase when the Cr content exceeded 5%, while the Cr species was not observed in the XRD patterns of the catalyst with a lower Cr content. The pore diameter of the catalyst was 2nm, irrelevant to the Cr content. The Cr/SiO2-G with 5% Cr exhibited largest surface area and highest catalytic activity; at 750℃, the conversions of ethane and CO2 are 79.29% and 23.74%, respectively, with the yield of ethylene being 67.91%. The catalyst containing 5% Cr exhibits appropriate redox properties, which may be relevant to its high catalytic activity for the ethane dehydrogenation with CO2.
Abstract: Electro-oxidation of methanol was studied on titanium supported nanocrystallite Pt and Ptx-Sny catalysts prepared by electrodeposition techniques. Their electro-catalytic activities were studied in 0.5mol/L H2SO4 and compared to those of a smooth Pt, Pt/Pt and Pt-Sn/Pt electrodes. Platinum was deposited on Ti by galvanostatic and potentiostatic techniques. X-ray diffractometer (XRD) and energy dispersive X-ray (EDX) techniques were applied in order to investigate the chemical composition and the phase structure of the modified electrodes. Scanning electron microscopy (SEM) was used to characterize the surface morphology and to correlate the results obtained from the two electrochemical deposition methods. Results show that modified Pt/Ti electrodes prepared by the two methods have comparable performance and enhanced catalytic activity towards methanol electro-oxidation compared to Pt/Pt and smooth Pt electrodes. Steady state Tafel plots experiments show a higher rate of methanol oxidation on a Pt/Ti catalyst than that on a smooth Pt. Introduction of a small amount of Sn deposited with Pt improves the catalytic activity and the stability of prepared electrode with time as indicated from the cyclic votlammetry and the chronoamperometric experiments. The effect of variations in the composition for binary catalysts of the type Ptx-Sny/Ti towards the methanol oxidation reaction is reported. Consequently, the Ptx-Sny/Ti (x∶y (8∶1), molar ratio) catalyst is a very promising one for methanol oxidation.
Abstract: The active carbon and active char were used as the desulfurizer and BET, XPS techniques were used to analyze and characterize the physical and chemical properties of the sorbent. The results show that the desulfurization ability of the active carbon (char) has a close relation with its surface chemical functional groups，especially with C—O group. The reaction temperature has a great impact on the desulfurization performance of the active carbon (char). The desulfurizer shows a high reactivity, high sulfur capacity and fewer side reactions at 150℃～180℃. Meanwhile, the steam can promote the removal of hydrogen sulfide.
Abstract: CuO-CeO2-MnOx/γ-Al2O3 granular catalysts were prepared by sol-gel method. Performance of the CuO-CeO2-MnOx/γ-Al2O3 catalyst for the selective catalytic reduction (SCR) was explored in a fixed bed adsorption system. The optimum temperature ranges for SCR of NO over the CuO-CeO2-MnOx/γ-Al2O3 catalysts were 250℃～400℃. The maximum efficiency maintained near to 99% at 350℃. With higher loading of Ce, the SCR activity increased at low temperature range (100℃~300℃). Preliminary tests were carried out to study the behavior of NH3 and NO over catalyst in the presence of oxygen. The NH3 oxidation experiments showed that both NO and N2O were produced gradually with temperature rising. The NO oxidation experiments revealed that NO was oxidized to NO2 over the catalyst. The NH3 and NO desorption experiments showed that NH3 and NO could be adsorbed on CuO-CeO2-MnOx/γ-Al2O3 granular catalysts. The less adsorption capacity and the over-oxidation of NH3 were the main cause of lower activity at high temperature. The transient behavior of NH3 and NO was also studied. It was found that the SCR reaction was zero order to NH3 and first order to NO.
Abstract: Elemental sulfur can be produced simultaneously during H2-regeneration of SO2-adsorbed V2O5-CoO/AC catalyst-sorbent when effluent gas of the regeneration is recycled back to the reactor. SO2 removal activities of the catalyst-sorbents after the regeneration under different conditions were studied in detail. It is found that elemental sulfur production requires transformation of sulfur forms between the solid phase and the gas phase, which results in residual sulfur in the catalyst-sorbent and a decrease in the subsequent SO2 removal activity. The residual sulfur occupies a portion of micro-pores of V2O5-CoO/AC and increases its surface acid amounts. Both of them can be attributed to the decrease in SO2 removal activity. H2 purge after the regeneration is effective for converting the residual sulfur to H2S and increasing the SO2 removal activity. NH3 treatment after the regeneration is also helpful to improve the SO2 removal activity.
Abstract: The effects of alkali metal K on the release characteristics of NO during the co-combustion of a Tiefa coal deashed by acid washing and mixed with corn straw or different proportions of KOH were investigated using an online themogravimetric-gas chromatographic system. The results indicate that it is effective to inhibit the release of NO to add a certain proportion of straw in the deashed samples. As the proportion of straw increases, the peak number of release rate of NO gradually changes from one peak to two peaks. When the content of K increases in the deashed coal samples mixed with a low proportion of straw and KOH, it has a stronger catalytic effect on the reduction reaction of NO, and when the content of K reaches a certain value, the catalytic effect does not increase. The lower the O2 content in the combustion atmosphere, the better the reduction of NO.
Abstract: Room-temperature ionic liquids were used as catalysts for removal of trace olefins from the aromatics. The influences of various reaction parameters such as reaction time, dosage and type of catalyst were investigated. The experimental results demonstrated that the [bmim]Br-AlCl3 ionic liquid exhibited excellent activity under mild reaction conditions, with above 99% conversion of olefins and the bromine index of the aromatics varied from 773.5 to below 10. Furthermore, the ionic liquids could be reused easily. A possible reaction mechanism was proposed.
Abstract: The melting behavior of Au147 cluster supported on graphite and the effect of metal-substrate interaction on the cluster structure were studied by the Monte Carlo simulation. An icosahedra Au cluster and AB-stack graphite was first built, and then the melting process was investigated by recording the cluster structure of each state. The results show that the Au cluster begins to melt from exterior to interior with increasing temperature, and generates a two-dimension island structure. The strong interactions between metal and graphite can make Au atoms monolayered disperse on the graphite surface. Moreover, the enhancement of interaction can lead to a close attachment of metal atoms to the substrate.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
