Abstract: Using fractal theory as tool, coupling with inner pore structure of semi-coke by mercury intrusion method, the fractal characteristics of pore structure were studied. Through determining the fractal dimension of pore volume quantitatively, the change of fractal dimension of pore volume with different coking temperatures and different spatial positions during pyrolysis was investigated. The results show that there is no relationship between the fractal dimension and the pore structure with pore diameter >5μm. However, the pores with diameter of 20nm～5μm can be properly characterized by the fractal theory, and a fractal dimension range of 2.45～2.83 is obtained in this work. The fractal dimension of pore volume under identical spatial position is high at low temperature, then decreases and increases and finally decreases with the increasing temperature. But a small variation of the fractal dimension, less than 0.15, is observed under identical spatial position. It shows that the effect of coking temperature on the fractal dimension is not remarkable. Additionally, the fractal dimension of pore volume at the center and brim position of coke cake is greater than that of the middle position under identical coking temperature. It indicates that the pore structure at the center and brim of coke cake is more complex than that of the middle poison.
Abstract: Based on the Gibbs energy minimization method, biomass gasification with airsteam through thermodynamics method was analyzed to get the relationship between reaction conditions and the products gas compositions. The gasification features under both atmospheric pressure and elevated pressure were computed contrastively. The correlation curve of steam to biomass ratio (S/B), which corresponds to the maximum fraction of fuel gas, and equivalence ratio (ER) under different pressures was obtained through statistic regression analysis. The computation shows that compared with gasification under atmospheric pressure, the equilibrium temperature is higher in pressurized system, and the molar fraction of fuel gas is relatively lower while methane content increases remarkably. The S/B increases with increasing pressure. More Steam is needed for pressurized gasification. By adjusting S/B, different H2/CO ratios can be obtained. The ratio of H2/CO is approximately 2 both under atmospheric and 5.0MPa pressure in the computations, in which T=1173K and S/B=1.02. The optimal S/B has a perfect linearity with ER under different pressures. As temperature equals to 1173K, the relationship of the optimal S/B and ER and pressure is expressed as following: S/B=－1.48×ER－4.49 E×10－5×p2 + 5.83 E×10－3×p + 0.32.
Abstract: To study the chemical mechanisms of the formation of high H2S concentrations in natural gas, thermal simulation experiments on the reaction between natural gas and solid calcium sulfate were carried out in an autoclave under high temperature and high pressure. Properties of the reaction products were analyzed by gaschromatogram, microcoulometry, Fourier transforminfrared spectrum and X-ray diffraction methods. Thermodynamic characteristics of thermochemical sulfate reduction (TSR) and the reaction kinetics were investigated. It was found that natural gas could react with solid calcium sulfate under high temperatures, and that hydrogen sulfide, carbon dioxide, calcium carbonate, water and carbon are the main products. TSR of natural gas with solid calcium sulfate is thermodynamically possible and high temperature is favorable to the reaction. The reaction with longchain hydrocarbons can take place more easily than shortchain ones. According to the reaction model, the activation energy of the reaction is 96.824kJ/mol.
Abstract: Carbon nanotubesupported Co-Mo catalysts with different Co/Mo atomic ratio were prepared by pore volume impregnation. These catalysts were used in the hydrocracking reaction of Gudao vacuum residue, and the catalytic properties were compared with γAl2O3supported Co-Mo catalysts under the same reaction conditions. It was found that the catalytic properties of Co-Mo/carbon nanotube (CNT) catalysts are inferior to Co-Mo/γAl2O3. However, the Co/Mo atomic ratio has great effect on the catalytic activity of Co-Mo/CNT; the Co-Mo/CNT catalyst with Co/Mo atomic ratio of 0.50 has the best catalytic properties, whereas for Co-Mo/γAl2O3 catalyst the best Co/Mo atomic ratio is 0.35.
Abstract: Supercritical pentane extraction and fractionation was used to separate Dagang vacuum residue into 16 fractions and a nonextractable endcut. The narrow fractions were characterized by composition and average molecular structure. Furthermore, the narrow fractions were separated into the saturate, aromatic, resin and asphaltene. Their composition, molecular weight distribution and average molecular structure were also studied in detail. The properties of saturate, aromatic, resin and asphaltene show many differences, such as simpler molecular structure of the saturates， lower molecular weight of the aromatics， more sulphur and nitrogen contents of the resin， wider molecular weight distribution from 200 to 40000 of the asphaltene.
Abstract: The oxidation of BT and DBT in model light oil by potassium ferrate was investigated. The results show that the oxidation activity of K2FeO4to BT and DBT in water phase is lower because K2FeO4 reacts rapidly with water to form brown Fe(OH)3 to lose the ability of oxidation to organic sulfur compounds. The oxidation activity of K2FeO4 to BT and DBT increases markedly in acetic acid. The addition of the solid catalyst to acetic acid medium can remarkably promote the oxidation of organic sulfur compounds. The DBT of 98.4% and BT of 70.1% can be converted under the condition of room temperature, atmospheric pressure, acetic acid/ model oil (volume ratio)=1.0, K2FeO4/S (mol ratio)=1.0 and catalyst/K2FeO4 (weight ratio)=1.0.
Abstract: Taking into account the chemical reaction rate, internal diffusion and reaction heat, the theoretical model of regeneration process was established to investigate the regeneration within large coked catalyst particle. The results showed that at 650℃, limited by the chemical reaction rate, regeneration process was characterized by the homogeneous model. At temperature over 750℃, internal diffusion of gaseous reactant being the controlling step, the distinct radial profiles of oxygen partial pressure and carbon content were established. The maximum temperature rise in a single spherical catalyst particle increased with the increase of initial regeneration temperature. The maximum temperature rise also increased with the increase of carbon load and CO2/CO mol ratio in product gas. However, the regeneration time needed to reach one burn-off degree was prolonged. The temperature throughout the catalyst particle was homogeneous. The influence of gas flow rate on the regeneration process could be neglected in the case of eliminating external diffusion.
Abstract: Nickel ferrite, NiFe2O4, with spinel structure was prepared by citrate coordination method. The samples were characterized by X-ray diffraction (XRD) thermal gravimetric analysis (TGA). When the weight of NiFe2O4 sample was 0.5g, the optimum reduction condition for the preparation of oxygendeficient nickel ferrite, NiFe2O4－δ, reduced by H2 was as follows: reduction temperature was 320℃, H2 flow rate was 40mL/min and reduction time was 3h. The results also showed that the higher reduction temperature and higher H2 flow rate as well as longer reduction time led to an excessive reduction of NiFe2O4－δ and the destructiveness of its spinel structure, resulting in the formation of FeNi alloy Fe(Ni) as well as α-Fe phase.
Abstract: Using incipient impregnation, solgel method and conventional drying, and solgel and supercritical drying techniques, three kinds of 20% Ni/Al2O3 catalysts have been prepared, the catalyst samples were characterized by means of BET, XRD, H2-TPR and H2-TPD. Catalytic performances of the different catalysts for CH4-CO2 reforming reaction were investigated in a micro fluidized bed reactor. Strong interaction between Ni species and support Al2O3 is found and NiO and spinel NiAl2O4 were formed in the aerogel catalyst, but weaker interaction is observed in the impregnation catalyst and xerogel catalyst. Among the catalysts examined, the aerogel catalyst exhibits high specific surface area, low bulk density, high Ni reduction degree and Ni dispersion degree. Excellent catalytic activity and stability were achieved via the combination of aerogel catalyst and fluidized bed reactor. The fluidization of aerogel porous agglomerates provides high bed expansion and long gas residence time, which remarkably improves the mass transfer. Thus the deposited carbon was quickly gasified and only a limited amount of carbon was formed on aerogel catalyst. For the impregnation catalyst and xerogel catalysts, low bed expansion and little particles circulation result worse efficiency of mass transfer and short gas residence time, which decrease the rate of carbon gasification, and thus result in the carbon deposition. The characterization revealed that massive graphite carbon deposition is the most important reason resulting in the deactivation of the impregnation catalyst and xerogel catalysts.
Abstract: Effects of Mo addition and the reaction temperature on the activity, the selectivity and the anticarbondeposition of over Ni/ZnO catalyst for ethanol steam reforming were studied. The results of reaction at 773K suggested that the activity and selectivity to H2 of Ni/ZnO catalyst were promoted after the appropriate addition of Mo. The activities of the catalysts increased with the increase of the reaction temperature. Ethanol was converted completely at 823K. At 873K, NMZ-2 catalyst, in which the content of Mo was 0.83%, showed the optimum activity, the highest selectivity towards hydrogen and the best stability among the catalysts. The ability of anti-carbon-deposition of NZ can be promoted by addition of Mo, accordingly, the stability of this catalyst is improved. TPR and XRD results show that addition of Mo is contribute to the dispersion of nickel oxide over ZnO and weakens the interaction between Ni oxide and the support. Therefore, the activity, selectivity and stability of Ni/ZnO catalyst are improved.
Abstract: The thermodynamical stuty indicates that the synthesis of propylene carbonate (PC) from urea and propylene glycol is possible. The reaction process for synthesis of PC was investigated using ZnO catalyst. It was a stepwise process. At first, urea decomposed into isocyanic acid, which interacted with ZnO to form a relatively steady isocyanate species. Then propylene glycol reacted with isocyanate species to form hydroxypropyl carbamate (HPC), and the HPC lost ammonia to form PC. The catalysis of ZnO was striking in urea decomposition and the transformation of HPC to PC.
Abstract: Selective catalytic reduction of NO by methane in the presence of excess oxygen over CoH-FBZ zeolite composite catalyst has an advantage over the physical mixture of CoH-Y and CoH-Beta. The interaction between NO or NO+O2 and the catalyst revealed by adsorption and temperatureprogrammed desorption (TPD) technique, results directly in the effect of the topological structure of supports upon the stability of N-and O-species on the surface of the catalysts. The NO+O2-TPD profile of the CoH-FBZ catalyst exhibits two NO2 desorption peaks at 630K and 660K, respectively. This indicates that new adsorption centers for-NOy are formed over the CoH-FBZ and adsorbed more stably on CoH-FBZ than on CoH-Y or CoH-Beta, NO does in a similar manner. The synergism of the newly formed Co sites and the new strong acidic sites contributes to the novel CH4-SCR catalytic properties of the CoH-FBZ catalysts.
Abstract: A systematic study of the structure, bonding and relative thermodynamic stability of known crystalline nickel phosphides, such as Ni3P, Ni12P5, Ni2P, Ni5P4, NiP, NiP2 and NiP3, were carried out by density functional theory. The elastic behaviors for structurally lesscomplex compounds (Ni2P and NiP3) were then predicted. These data may be helpful in understanding the catalytic behavior of nickel phosphides.
Abstract: Adsorption and desorption of acetylene and propylene on zeolites ZSM-5, 13X, Y, MOR, 5A, SAPO-34 as well as on catalyst supports SiO2 and γ-Al2O3 were investigated at 80℃. The results illustrated that there exist strong interaction between the adsorbates and the zeolites, but SiO2 and γ-Al2O3 absorb little acetylene and propylene under the conditions here. On the zeolites with the same topological structure framework, the adsorption capacity for propylene and acetylene decreases with an increase of Si/Al ratio; while the adsorption capacity for propylene is always higher than that for acetylene on the same zeolite. Modification of zeolite may enhance its adsorption capacity; over a chemically modified β zeolite, the saturation adsorption amounts for acetylene and propylene at 80℃ reached 0.11mmol/g and 4.89mmol/g, respectively, which were much higher than the values reported in literature up to now.
Abstract: The diffusion of ethanethiol in MFI and MOR was investigated by Molecular Dynamics (MD). The results show that the diffusion coefficient decreases with an increase in the quantity of ethanethiol adsorbed. The zeolites of flexible and inflexible structures are different in diffusion coefficient. For MFI, the diffusion coefficients in flexible and inflexible structures are 3×10－10m2/s and 4×10－9m2/s, respectively; this order is reversed for MOR, the diffusion coefficients in flexible and inflexible structures are 2×10－7m2/s and 3×10－8m2/s, respectively. The diffusivity of ethanethiol in flexible MOR is higher than that in flexible MFI, because the 12 member ring in MOR is larger than the 10 member ring in MFI. For MFI, the adsorptive sites in both intersection channel and straight channels are similar in the energy of interaction; for MOR, however, some differences occur between 12 member ring and 4 member ring.
Abstract: The gas holdup, axial solid concentration distribution and particle size distribution in a slurry bubble column reactor were investigated experimentally by using air as the gas phase, tap water as the liquid phase, and quartz sands as the solid phase. The effects of superficial gas velocity, average solid concentration and axial location were discussed. A correlation formula between gas holdup and operating parameters has been obtained.
Abstract: Liquid residence time distribution in an entrained flow bed was studied. The effect of liquid flux, gas flux and gas momentum on the liquid residence time distribution was investigated. As the liquid flux increase, the curve of the liquid residence time distribution becomes higher and narrower and the mean residence time becomes shorter. The liquid residence time distribution moves forward when the gas flux increases, but the effect recedes when the gas flux is over 4L/min. The gas momentum has a great effect on the liquid residence time distribution when the liquid flux is smaller than 60L/h, and the larger the gas momentum, the longer the mean residence time . The liquid flow pattern was studied in both centersection and wallsection based on the experimental value analysis and the phenomenon in the experiment. The mathematic model is established to simulate the liquid residence time distribution in the entrained bed, and the simulating value is fitted well with the experimental value.
Abstract: The effects of temperature, residence time, and pressure on the degradation of polyethylene (PE) to oil were investigated in supercritical water (SCW) using a 180mL continuous reactor. The yield of oil product increases with the increase of temperature, reaching 79% at 530℃, and then decreases as the temperature further increases. The yield of gas product increases from 3% to 22% as the temperature increases from 500℃to 550℃. The product distribution shifts toward shorter chain hydrocarbons with the prolongation of reaction time. Furthermore, the ratio of alkenes to alkanes of products increases with the increase of temperature and pressure, and decreases with the increase of reaction time. The effect of pressure on both products' yield and composition is less significant.
Abstract: The solid-phase photocatalytic degradation of polyvinyl chloride (PVC) film in air was investigated . The photodegradation of the PVC and PVC-TiO2 was compared with that of plasma-treated PVC and plasma-treated PVC-TiO2 in terms of weight loss and scanning electron microscopic (SEM) analysis. The results show that the weight loss of plasma-treated PVC film is only 1.536%, while the weight loss of PVC-TiO2 film treated by plasma amounts to 1.966% . The SEM of the PVC-TiO2 film treated by plasma shows that there is a lot of crack on the surface after photodegradation. Furthermore, the surface wettability and surface structure of PVC after nitrogen plasma treatment were characterized by using contact angle and surface tension detector, X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR). The experiment indicates that the surface free energy and wettability of PVC treated by plasma increase greatly. XPS analysis of the plasma-treated PVC film shows that the surface concentration of oxygen increases while that of chlorine decreases after plasma treatment. ESR analysis reveals that the signal of radical on the surface of the plasma-treated PVC film is enhanced after treatment. The free radicals on the surface of plasma-treated PVC get the activating energy of photocatalytic degradation decreased because of higher chemical activity of the free radicals , which favors the photodegradation of plasma-treated PVC-TiO2.
Abstract: The effect of pyrolysis temperature on yield of polyvinyl chloride (PVC) pyrolysis char was systematically investigated in a fixed-bed reactor. The thermogravimetric characteristics of PVC were also investigated. The pyrolysis kinetics was analyzed by Coats-Redfern integration method. The fixed bed results show that with increasing pyrolysis temperature, the yield of char during pyrolysis of PVC decreases. The TG/DTG results show that with increasing temperature, the yield of volatile matter increased. The TG/DTG curves of PVC pyrolysis shifts to higher temperature with increasing heating rate. The kinetic result illustrates that the pyrolysis can be divided into two stages based on different activation energies. The first stage has lower activation energy about 50kJ/mol, and that of the second stage is about 245kJ/mol.
Abstract: Thermal decomposition is an effective method to reduce N2O concentration in flue gas. The experiment was conducted with a fix bed reactor. The N2O concentrations before and after reactor under different O2 concentrations were measured and compared. The results show that the increase of oxygen concentration slows the reaction speed of thermal decomposition of N2O. The influence mechanism of oxygen concentration on the thermal decomposition of N2O is simulated with P. Glarborg’s model. The increase of oxygen will reduce the concentrations of H and OH which mainly decide the reaction speed of thermal decomposition of N2O. It is necessary to control the oxygen concentration to increase the de-N2O efficiency by thermal decomposition.
Abstract: The experimental investigation of methane catalytic combustion on coated noble catalyst was carried out, using an integral micoreactor under the condition free of external and internal diffusion limitations. Forty-five groups of experimental data for methane conversion were obtained under different space velocities and temperatures. The partial least-square（PLS）and The NelderMead simplex search methods were employed to estimate the parameters of the intrinsic model. The intrinsic model of lean methane catalytic combustion on the HPA(KMK) catalyst is rA＝7.32×109 exp(－64550/RT)CA. The parameters obtained are consistent with the Physical-Chemical rules and statistically reasonable.
Abstract: The macro-kinetics of diphenyl carbonate synthesis was studied over Pd-Cu/La0.5Pb0.5MnO3 catalyst in a trickle-bed reactor. The catalyst particle size was φ2.0mm×3mm. A power type macro-kinetic model was employed in the present study. The model parameters-were regressed-in the kinetics. The statistic test and its residual error distribution have been made, respectively. The results show that the values calculated by power type macro-kinetic models can be good agreement with experimental data. Furthermore, the model can provide the theory basis on simulation and design of the large scale synthesis of diphenyl carbonate in trickle-bed reactor.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
