Abstract: The effect of the modification with acetone under photocatalysis on the surface of macerals was studied, which aimd to find the method to enlarge the difference of the surface wettability of macerals. The influence of the modification time on the surface wettability and structure of Shenfu fusain and vitrain was researched. The results showed that the modification could obviouly change the surface properties of macerals. There was the biggest difference of wettability between Shenfu fusain and vitrain under the modification for 3min. The mainly changing surface groups in the modification process were C－O, C=O, COO－, etc. Moreover, the change of the contents of C=O and COO－ on the surface of Shenfu fusain were more obviously than Shenfu vitrain.
Abstract: Using H2 as a reactant gas, the reaction characterization of hematite oxygen carrier was investigated in a thermogravimetric analyzer (TGA). The solid reduction products were characterized by XRD (X-ray diffraction) and SEM-EDS (Scanning Electron Microscope-Energy Dispersive Spectrometer). The results show that there is a maximum reaction rate when the conversion is 0.11. In this stage, Fe2O3 as an active phase was converted to Fe3O4 and the reduction reaction was easy to happen. Then, there is a decrease of reaction rate. When the conversion degree of hematite oxygen carrier was 0.178, the solid reduction products were composed of Fe3O4 and FeO. When the conversion is 0.477, Fe3O4, FeO and Fe were all found in the reduction products. SEM-EDS results show that the grains at the surface of hematite oxygen carrier were gathered and grown up, and the particle volume shrinkage and sintering effect are observed, especially in the region rich in Fe element. However, a relative stable structure was seen in the region rich in SiO2 or Al2O3 contents. Further, compared with the results based on interconnected beds, the sintering of hematite was alleviated due to a good inert material distribution, which kept a good long-term reactivity of hematite oxygen carrier.
Abstract: Wet removal of NO from coal-fired flue gas by UV/H2O2 advanced oxidation process was investigated in a self-designed UV-bubble reactor. Several main influencing factors including UV intensity, H2O2 initial concentration, NO initial concentration and flue gas total flow on the removal efficiencies of NO were studied. The results show that the NO removal efficiency increases with increasing UV light intensity and H2O2 initial concentration. When they reach a certain value, the growth rate of the NO removal efficiency begins to become smaller. In addition, the NO removal efficiency approximately linearly decreases with the increase of the NO initial concentration and the total flow of flue gas. Based on the qualitative and quantitative detection of related ions in solution by ion chromatography (IC) and the mass balance of nitrogen element in NO, the removal paths of NO by UV/H2O2 process was discussed in depth.
Abstract: The first step of biomass pyrolysis corresponds to water evaporation. Thermal analysis instrument was used to determine the mass and heat change of fir wood during drying process. Non-isothermal drying kinetics model was derived to explore the mechanism of heat and mass transfer. The results show that moisture content decreases rapidly and weight loss peak appears at 80℃. Page model for non-isothermal drying kinetics can well simulate wood drying process and the drying activation energy is 12.6kJ/mol. Water and heat transfer have close relationship and the dry heat is mainly used for water evaporation. The value of heat requirement is 426kJ/kg and the simulated results show good agreement with experimental values.
Abstract: The kinetic characteristic of cotton stalk pyrolysis catalyzed by six kinds of additives including NaOH, Na2CO3, Na2SiO3, NaCl, TiO2 and HZSM-5 was investigated by using the thermogravimetric analysis. The weight loss behavior was simulated by assuming the three main components of the cotton stalk sample to experience the first order parallel and independent pyrolysis reactions. The pyrolysis kinetic parameters were estimated by the nonlinear least squares algorithm. The results show that the kinetic parameters of the three components are changed by adding additives. Under the action of the alkaline additives, the activation energies of cellulose and hemicellulose can be reduced to a greater degree. The stronger the basicity of the additives, the lower the pyrolysis activation energies for the cellulose and the higher for the hemicellulose. Neutral additive NaCl has little effect on the pyrolysis activation energy. Surface acidic additives make the pyrolysis activation energies increase for the cellulose and hemicellulose. However, all the additives have no significant effects on the pyrolysis activation energies for lignin.
Abstract: To understand the mechanism of levoglucosan formation in cellulose pyrolysis, the pyrolysis of cellobiose as a model compound was investigated theoretically by using UB3LYP/6-31G(d) methods. Three kinds of pyrolysis reaction paths were designed; the equilibrium geometries of the reactants, intermediate, transition states, and products were optimized. The standard thermodynamic and kinetic parameters of pyrolysis reaction were calculated at different temperatures. The results showed that the free radicals IM1a and IM1b can be formed by homolysis of glycosidic bond and the reaction is endothermic with an energy of 321.26kJ/mol. Free radical IM1a may react further via transition state TS1a and lead to the formation of levoglucosan, with an energy barrier of 202.72kJ/mol. Compared to consecutive reactions, concerted reaction of the formation of levoglucosan P1 and glucopyranose P2 via the transition state TS2 in pyrolysis of cellobiose has a lower energy barrier of 377.54kJ/mol. Addition of H+ would be in favor of breakage of glycosidic bond; the intermediate IM3 formed can hardly transform to levoglucosan, which is in accord with the related analysis of experimental results.
Abstract: The experiments on the gasification of corncob chips with steam-oxygen enriched air was carried out in an atmospheric two-stage fixed bed gasifier. The effects of equivalence ratio (ER), oxygen concentration (OC) and steam to biomass ratio (S/B) on the gasification temperature, gas compositions, lower heating value, gas yield, carbon conversion and cold gas efficiency were investigated, and the gasification characteristics between conventional downdraft fixed bed and two-stage fixed bed was compared. The results show that under the operating conditions of ER=0.27, H2 content, CO content and cold gas efficiency reach their maximums; Enhancing oxygen concentration can optimize the gasification performance, but it is less to further improve the fuel gas quality as the OC exceeds 90%. By increasing S/B, the H2 content, CO2 content and gas yield are increased, but the CO content, cold gas efficiency and carbon conversion are decreased. H2 content reachs maximum of 33.3% at the S/B of 0.6, while H2/CO ratio reachs 1.32. Compared with conventional downdraft fixed bed, the two-stage fixed bed has a higher gasification temperature, H2 content, carbon conversion, cold gas efficiency and a lower tar content.
Abstract: The surface tension, kinematic viscosity, abrasion resistance, oxidation stability and soot emission characteristics of a biodiesel-diesel blend fuel were investigated. The results showed that the surface tension of the blend fuel varies in terms of parabola trend with the increase of biodiesel content and decreases according to a power function with the increase of temperature. The biodiesel exhibits less wear spot diameter and greater maximum bite limit pressure than the diesel fuel. The oxidation stability of the blend fuel is improved obviously when the biodiesel content is 40%～70%. With the increase of the biodiesel content, the viscosity of the blended fuel is increased linearly, while the soot emission, when burned as the engine fuel, is decreased significantly.
Abstract: Ultrasonic was applied to assist the catalytic aquathermolysis reaction of heavy oil, and the effect of catalyst and ultrasonic on the physical and chemical properties of Shengli Gudong heavy oil was investigated. Compared to catalytic aquathermolysis reaction, the results of ultrasonic assisted catalytic aquathermolysis indicate that the viscosity of heavy oil is reduced by 86.2%, and the composite technology can further decrease the average molecular weight of heavy oil, increase the saturate and aromatic contents, decrease the resin and asphaltene contents, improve the mol ratio of nH/nC, and decrease the heteroatoms content of heavy oil. The results of dynamic simulation experiments show that in-situ ultrasonic assisted catalytic aquathermolysis exhibits good performance with the 53.91% heavy oil recovery and 80.5% viscosity reduction. The experimental results prove that the combination of ultrasonic and catalyst has a synergetic effect, which attributes to the reduction of viscosity and improvement of heavy oil quality.
Abstract: The oxidative desulfurization for a simulated oil(S content 1540×10-6) consisting of model sulfur compounds of dibenzothiophene(DBT) and toluene solvent in a H2O2/WO3/ZrO2 oxidative system was studied. The influence of oxidation temperature， reaction time， the amount of oxidant and the dosage of catalyst on the conversion of DBT were investigated. The experimental results reveal that under an optimum oxidative desulfurization condition with the temperature of 50℃， the reaction time of 90min， the oxidant dosage of V(oil)∶V(H2O2)=20∶1 and the catalyst dosage of 0.02g/mL oil， more than 96% of DBT are oxidized to dibenzothiophene sulfone(DBTOs) that can be easily removed. Furthermore， the oxidation kinetics of dibenzothiophene was investigated. The oxidation of DBT can be treated as a first-order reaction， the apparent activation energy Ea is 55.37kJ/mol and the pre-exponential factor A is 3.35×107min-1.
Abstract: Silica nanotubes (SNT) were synthesized with carbon nanotube (CNT) as a template and used as the support to prepare ruthenium-based catalyst by slurry impregnation method. The catalyst was characterized by N2 physisorption, XRD, H2-TPR and TEM; its performance in Fischer-Tropsch synthesis (FTS) was evaluated in a fixed-bed reactor at 503K and 1.0MPa and compared with that of SiO2 supported ruthenium catalyst (Ru/SiO2). The results indicated that ruthenium oxides can be completely reduced at 623K by H2. For the SNT supported ruthenium catalyst (Ru/SNT), the ruthenium particles are mainly located inside the nanotubes and are still well dispersed on SNT after H2 reduction. Compared with Ru/SiO2, the Ru/SNT catalyst exhibits higher activity in FTS because of the higher dispersion of ruthenium particles in SNT.
Abstract: Ni-Sn-Cr/AC catalyst was prepared through impregnation with Ni(NO3)2·6H2O, SnCl4·5H2O and Cr(NO3)3·9H2O as precursors and activated carbon as support; it was used in vapor phase carbonylation of methyl acetate to proroduce acetic anhydride in a continuous flow type fixed-bed reactor. The effects of each metal loading on the catalytic activity as well as the influence of reaction temperature, pressure, and time on the reaction behavior were investigated. The results showed that the Ni9%-Sn12%-Cr6%/AC catalyst calcined at 600℃ for 4h exhibits excellent performance in the carbonylation; over it under the optimized reaction conditions of 5.5MPa and 205℃, the conversion of methyl acetate and the selectivity to acetic anhydride reach 38.8% and 81.1%, respectively. The fresh catalyst and spent catalysts after reaction for different times on stream were characterized by means of X-ray diffraction and element analysis; the results suggested that Ni0 is main active sites. During the test, the activity of the catalyst is decreased dramatically with the time on stream, which could be ascribed to the loss of active component Ni, carbonaceous deposition and destruction of activated carbon framework.
Abstract: In recent years, much attention has been paid to slurry dimethyl ether synthesis technology due to its advantages in heat transfer, isothermal condition and efficient energy utility. However, the catalyst stability is a bottle-neck to restrict the commercial application. This paper studied the structure and physicochemical properties of Si-Al based catalyst prepared by the complete liquid-phase method. The catalysts were characterized by XRD, TEM, XPS and XRF technics, and then contrasted with traditional hybrid catalyst. The results indicated that there were different reason in their deactivation. Hybird catalyst deactivation was caused by Cu sintering, gathering and specific surface area decreasing. For Si-Al based slurry catalyst, the Cu loss during the reaction was an important reason leading to deactivation.
Abstract: A systemic thermodynamic analysis was conducted for the autothermal reforming of natural gas to produce hydrogen. A kinetic modeling was made for the autothermal reforming by employing the pre-mixed laminar model included in CHEMKIN package that incorporates the mechanisms of CH4 oxidation, steam reforming and dry reforming; kinetic parameters for methane reforming over Ni-based catalyst, widely used in the natural gas reforming industry, were adopted. The results show that the equilibrium composition of outflow gases is depended on the reaction temperature, the air-fuel ratio and water-fuel ratio. The pressure has a limited impact on the product distribution but has a remarkable impact on the time needed to reach the equilibrium. Under 715℃~730℃, 0.7MPa~1.0MPa, O2/CH4 of 0.60~0.70, and H2O/CH4 of 3.15~3.25, the fraction of H2 in the product is higher than 68%, while CO does not exceed 10% (dry basis) and the carbon deposition is close to 0. The kinetic analysis suggests two distinct stages during the autothermal reforming process. The initial stage is a rapid oxidation zone, where H2O and CO2 are the main products. The second stage is a slow conversion zone, where methane steam reforming reaction as well as water gas shift reaction and slight dry reforming take place, with H2, CO and CO2 being the main products. Adding H2O in the feed gas is a visible measure for avoiding hot spot in the reactor and controlling the formation of CO.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
