Abstract: The sodium release and transformation of Yili (YL) and Hutubi (HTB) coal were examined at different temperatures under N2, CO2 and H2O atmospheres. By using sequential extraction and wet digestion separately, the occurrence mode and content of sodium in raw coal and chars were measured. The migration of sodium in two coals was studied qualitatively and quantitatively. The results show that water soluble sodium in YL coal accounts for 80.08%, while in HTB, insoluble sodium is 61.54%. The volatilization of sodium in two coals increases with increasing temperature. Water soluble sodium in semi coke shows a decrease trend; ammonium acetate soluble sodium increases and then decreases; hydrochloric acid soluble sodium exhibits an increasing tendency. For YL volatilization of sodium is inhibited by CO2 while it is promoted by H2O compared with N2. At 900℃ volatilization of sodium under CO2 and H2O is 50.25% and 111.45%, respectively, of that under N2. CO2 atmosphere can inhibit volatilization of sodium in HTB. At 900℃ volatilized sodium under CO2 is 80.91% of that under N2. In H2O atmosphere, volatilization of sodium is higher than that in N2 before 800℃ and slightly lower than that in N2 at 900℃. The predominant sodium in YL coal is water soluble which volatilized during increasing temperature and transformed to hydrochloric acid soluble and insoluble sodium simultaneously. While for HTB, insoluble sodium is the dominant occurrence mode, followed by water soluble one. CO2 and H2O can promote transformation of insoluble sodium to soluble one in HTB coal.
Abstract: Based on the density functional theory of quantum chemistry and transition state theory, reaction mechanism of heterogeneous reaction of ketone char with NO and oxygen desorption of the products were examined. The results indicate that NO is more easily adsorbed on surface of the ketone char. The ketone group of armchair enhances the char heterogeneous reduction of NO; On account of oxygen concentration in the ketone of zigzag char may not be within the range where is beneficial to reduction of NO, the energy barrier value of heterogeneous reduction of ketone coal char and NO (495.45kJ/mol) is higher than that of the pure carbon-based char and NO (331.32 kJ/mol). Without the presence of CO, the P1 of intermediate products is more prone to oxygen desorption than the pure carbon-based char, and surface defects are produced. With the presence of CO, the ketone char provides surface free active sites for the oxygen desorption process, which reduces energy barrier of the process.
Abstract: Different ratios (3%, 6%, 9%, 12%, 15%) of acetone and ethyl acetate were added into crude bio-oil from fast pyrolysis to invest the effects of these two additives on the storage stability of bio-oil.The results show that both acetone and ethyl acetate can reduce the water content of bio-oil, and the ethyl acetate performes better than acetone.Compared to the blank control group, the water content decreases by 17.8%(from 16.32% to 13.41%) at 15% dose of ethyl acetate.The viscosities of bio-oil decrease a lot after adding acetone and ethyl acetate, and acetone shows more obvious effect.With the increasing of additive dose, the viscosity of bio-oil decreases.The viscosity of bio-oil decreases more than that of the control group by 37.20%, 57.78%, 71.92%, 79.79%, 84.67% with 3%, 6%, 9%, 12%, 15% dose of acetone, respectively.There is no significant difference in pH values among acetone and ethyl acetate addition groups and control group.According to the FT-IR and GC-MS analysis, it indicates that acetone and ethyl acetate inhibit the aging reactions of bio-oil during storage.
Abstract: Three MoS2 catalysts were synthesized by a hydrothermal method using different sulfur precursors such as thiourea, L-cystine and sulfur powder; their differences in the structure, morphology, and catalytic activity in the hydrodeoxygenation (HDO) of p-cresol were comparatively investigated. The results illustrated that the sulfur source has a significant influence on the morphology and surface area of the as-synthesized MoS2 catalysts. All the hydrothermally synthesized MoS2 catalysts show much higher activity in HDO than the commercial MoS2 sample. Among three MoS2 catalysts, the one prepared from thiourea, with a high surface area and flower-like morphology, exhibits the highest activity in HDO; over it, a deoxygenation degree of 99.3% is achieved at 300℃.
Abstract: SiO2-Al2O3, with a mass content of 5%, 10% and 15%, was synthesized by using a Al(NO3)3-NaAlO2 double hydrolysis method, with surfactant Pluronic P123 as template and Si(OC2H5)4 as Si source. The Co-Mo/SiO2-Al2O3 hydrotreating catalysts for lubricating oil were then prepared by co-impregnation method and characterized by a series of techniques such as XRD, N2 sorption, Py-FTIR, NH3-TPD, H2-TPR, TEM and XRF. The results show that the SiO2-Al2O3 support containing 10% Si is provided with abundant moderate-strong acid sites and partially ordered mesoporous structure; MoS2 particles are uniformly dispersed on the SiO2-Al2O3 surface. Moreover, the Co-Mo/10%SiO2-Al2O3 catalyst exhibits high amount of Bronsted acid sites and type Ⅱ CoMoS active phase. The catalytic performance was evaluated in a high-pressure fixed-bed reactor, with second vacuum side distillate oil as the raw material oil. The results show that the Co-Mo/10%SiO2-Al2O3 catalyst exhibits high activity in hydrotreating and paraffins and cycloalkanes are the main components in product oil. Under 380℃, 15 MPa, a space velocity of 0.6 h-1, and a hydrogen to oil ratio of 1000, the HDS and HDN values over Co-Mo/10%SiO2-Al2O3 exceed 99%. Meanwhile, the contents of S and N in the product are less than 10 and 2 μg/g, respectively, which can meet the requirements on the raw materials for the subsequent isomerization dewaxing process.
Abstract: The composite NiO-ZnO nanowires for desulfurization were synthesized using hydrothermal method. The effects of the ratio of ethanol to water in the solvent used for the nanowire synthesis were studied. The phase structure and morphology of the nanowire adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The desulfurization performance of the adsorbents were studied at the temperature of 350℃, pressure of 1.0 MPa, the volume space velocity of 6 h-1, and H2/oil volume ratio of 60. The results showed that the composite NiO-ZnO nanowire adsorbent has better morphology than others, the active catalytic site was determined to be Ni which seemed to have better dispersion and smaller particle size, and the Ni-Zn alloy preferred to desulfurization was formed, so its desulfurization performance was significantly improved. The desulfurization rate was increased up to 98%. After five circles of regeneration, the activity of the composite NiO-ZnO nanowire adsorbent can still maintain 90 h, which indicated that it possesses better reusability.
Abstract: Hierarchically porous alumina with three-dimensional interconnected pore structure was prepared by phase separation method with alumina sol as the seed crystals; the alumina material was then characterized by SEM, XRD, N2 sorption, mercury porosimetry and NMR. The results reveal that the ierarchically porous alumina is provided with macropores of 200-600 nm in gamma phase; it has a high surface area of 366 m2/g and narrow double pore size distributions at about 5 and 400 nm. As revealed by NMR, AlO4, and AlO6 are formed in the calcined alumina sample. It is then suggested that during the synthesis, PEO acted as a seed can inspire phase separation, generating the interconnected three-dimensional macropores, while the crystalline grain in the sol may induce the aluminum hydrates to form active AlOOH, which is then transformed to gamma crystalline phase by calcination even at mild temperature.
Abstract: La-modified HZSM-5 catalysts were prepared by impregnation method, and characterized by XRD, NH3-TPD, Py-FTIR and N2 adsorption/desorption techniques. Their catalytic performance in methanol to gasoline (MTG) reaction was evaluated in a fixed-bed tubular reactor at 350℃ and WHSV of 4.74 h-1 under ambient pressure. The results show that the introduction of La decreased the amount of acid sites, specific surface area and pore volume of HZSM-5 catalyst. The catalyst with La loading of 4% exhibited the best catalytic performance in MTG reaction, over which the lifetime and gasoline yield increased from 12 h and 52.69% to 16 h and 59.28%, respectively. In addition, the selectivity to aromatics in gasoline decreased markedly by 18% with increasing La content.
Abstract: MgCo2O4 composite oxides with spinel structure were hydrothermally prepared at 120℃ by using carbon sphere as template and urea as precipitant. K2CO3 solution was impregnated on MgCo2O4 and the K-modified catalyst was obtained. These catalysts were applied in catalytic decomposition of N2O and characterized by X-ray diffraction(XRD), nitrogen physisorption, scanning electron microscopy (SEM), temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of oxygen (O2-TPD), and X-ray photoelectron spectroscopy (XPS). Effect of catalysts preparation parameters such as mass ratio of cobalt and magnesium to carbon sphere, molar ratio of urea to metallic cations, on their catalytic activity was investigated. It is shown that the catalyst prepared with mass ratio 0.192 of cobalt and magnesium to carbon sphere, molar ratio 2 of urea to cobalt and magnesium cations, exhibits higher catalytic activity than others. Furthermore, 91% and 62% conversions of N2O could be reached over 0.02 K/MgCo2O4 catalyst at 400℃ after continuous running for 50 h under the atmosphere of oxygen-alone and oxygen-steam together, respectively, revealing that K-modified MgCo2O4 catalyst is stable under both reaction atmospheres.
Abstract: To investigate the relationship between the structure and catalytic activity, four types of MnO2 nano-catalysts with various crystal structures (α-MnO2, β-MnO2, γ-MnO2 and δ-MnO2) were synthesized by hydrothermal method, and their low temperature NH3-SCR activity were tested. The results indicated that catalysts with different structures showed various activities which followed the sequence of γ-MnO2 > α-MnO2 > β-MnO2 > δ-MnO2. It was found that γ-MnO2 showed highest catalytic activity and its NOx conversion rate surpassed 90% at the temperature range of 150-260℃. The catalysts were characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM), N2 adsorption-desorption, thermogravimetric(TG), infrared (FT-IR), temperature programmed reduction(H2-TPR) and pyridine infrared spectroscopy (Py-FTIR). It was inferred that the morphology of the α-MnO2 and β-MnO2 were nanorods, while γ-MnO2 and δ-MnO2 with the structures of nanoneedles. The specific surface area of the catalyst was not the dominant factor affecting the NH3-SCR activity at low temperature. The decent pore structure, strong redox property, abundant chemisorption oxygen and Lewis acid sites were responsible for high low temperature NH3-SCR activity of γ-MnO2 nano-catalyst.
Abstract: Tungsten carbides microspheresare synthesized by in situ reduction of ammonium met tungstate microspheres (AMT) precursors as a function of reaction time under CO/CO2 mixture atmosphere. The morphology, size and composition of the as-prepared tungsten carbide microspheres are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Pt nanoparticles with a diameter of 4.6 nm are loaded onto the surface of WC microspheres using a conventional sodium borohydride reduction method. The electro-catalytic activity and stability toward methanol electrooxidation (MOR) are investigated using cyclic voltammetry (CV) and chronoamperometry(CA). The resultant Pt/WCO-6 h catalyst exhibits low onset potential and excellent catalytic performances in comparison to the commercial JM Pt/C and Pt/WC-15 h catalysts. Further investigation shows that besides the synergistic effect between WC and Pt, the existence of WO2 might also play an important role in improving the electro-catalytic activity, indicating the positive effect of the surface oxide on the activity and stability of Pt/WC catalysts towards MOR.
Abstract: Direct methanol fuel cell (DMFC) research is highly focused due to its high energy density, portability and inexpensive. In the present study conventional platinum catalyst used for methanol oxidation is being replaced with nickel catalyst supported over nickel mesh. The electrode is synthesized by single step electro deposition technique. Synthesized electrode was characterized by SEM, EDAX and AFM techniques to know the surface morphology, composition and thickness of the catalyst respectively. The electro catalytic behavior of the nickel for methanol oxidation was evaluated using cyclic voltammetry technique. As the DMFC is compatible with both the acidic and alkaline electrolytes the working of the nickel mesh electrode is analyzed in both media. The results showed maximum current density of 0.025 and 0.030 A/cm2 in alkaline and acidic medium respectively with less potential around 0.4 and 0.2 V. The other parameters such as varying the concentration of methanol, electrolyte medium, scan rate and thickness of the catalytic layer were analyzed and optimized.
Abstract: An air-cathode single-chamber microbial fuel cells were constructed using the aging landfill leachate as substrate to study the influence of different anode modifications on microbial fuel cell performance in terms of the electricity productivity and the effects on the treatment of aging landfill leachate. After the carbon felt anode modification separately with heating, concentrated nitric acid, acidic potassium dichromate and mixed acid, the maximum output power density of cells increases by 104%, 241%, 51%, and 181%, respectively, and the removal of ammonia increases by 22.2%, 21.8%, 2.3% and 47.3%, respectively, while the removal efficiency of COD is improved less. As the pH value of landfill leachate increases, the conductivity decreases.
Abstract: NiY zeolites were synthesized in the system of Na2O-Al2O3-SiO2-H2O with the addition of nickel nitrate by crystallization directing agent and characterized by XRD, SEM, TEM, N2 adsorption-desorption, etc. The results show that the crystallinity and zeta potential decrease after an increase at first with the increasing of nickel added. It means that nickel nitrate can promote the formation of molecular sieve when Si/Ni(mol ratio) is greater than 5, while it has an inhibitory effect when Si/Ni(mol ratio) is less than 5. The NiY zeolites with 1.5-3 μm of size not only possess special morphology, six or four square columns with grooved structure, but also have a multiple porous structure including microporous and mesoporous. The sample test by cyclic voltammetry (CV) and polarization curve(LSV) in microbial electrolysis cell (MEC) indicates that the NiY zeolites with Si/Ni(mol ratio)=5 present the best electrochemical characteristics with an outstanding redox performance, a minimum overvoltage and the highest electrocatalytic activity. Moreover, the hydrogen production yield reaches 10.1 mL/4 mg in 12 h with the hydrogen purity of 81.69%, surpassing that with Pt electrodes by about 28%. It suggests that the NiY zeolites have a better hydrogen evolution activity and it is possible to replace Pt as a novel cathode catalyst in microbial electrolysis cell.
Abstract: Ship-like, oblate spheroid and nano sheet CeO2-MnOx mixed oxides were prepared by hydrothermal method and characterized by N2 sorption, XRD, SEM, TEM, H2-TPR, Raman spectra and XPS. The relationship between the structure of CeO2-MnOx and their catalytic performance in lean methane combustion were then investigated. The results reveal that the catalytic performance of the mixed CeO2-MnOx oxide was greatly depended on its morphology. Among all of the samples, the mixed oblate spheroid CeO2-MnOx oxides with most oxygen vacancies, Ce3+ content and surface active oxygen exhibited the highest activity in lean methane combustion, with a complete CH4 conversion at 540℃. Following it, the mixed ship-like CeO2-MnOx oxides catalyst had 94.05% of the CH4 conversion at 540℃. On the contrast, the mixed nano sheet CeO2-MnOx oxides catalyst presented the lowest catalytic activity with only 89.68% CH4 conversion at the same reaction temprature owing to its lower oxygen vacancies and surface active oxygen.
Abstract: For comparing the effects of the structural properties of adsorbents on the capability for hydrogen storage, three kinds of adsorbents, including activated carbon, graphene sheets (GF) and metal-organic frameworks (MOFs), were synthesized and undertaken adsorption equilibrium tests of hydrogen at temperature of liquid nitrogen. The structural characterization of the prepared samples were firstly conducted employing Micromeritics 3Flex for the adsorption data of nitrogen at 77 K. Then, the adsorption equilibrium tests of hydrogen on those adsorbents had been respectively measured under low pressure of 0-0.1 MPa at temperature of 77-87 K and under high pressure of 0.1-8 MPa at 77 K. Lastly, the relationships of the hydrogen uptake and the structural properties of the adsorbents were analyzed. Results show that the hydrogen uptake of the physical absorbents is mainly affected by the micro-pores with pore size less than 1nm under low pressure, but under high pressure, the maximum amount of excess hydrogen adsorption on the porous material is positively correlated with the BET specific surface area of the material, and the slope is 0.0059 mmol/m2.
Abstract: Activated carbon was prepared by one-step method at low temperature using sawdust as material. Effect of preparation and adsorption conditions among liquid-solid and gas-solid on desulfurization performance was discussed. The results show that the optimum preparation conditions are as follows:mass ratio of 1:1 for impregnation liquid (with HNO3 mass fraction of 30%) and sawdust, NiO loading of 5% on surface of adsorbent, impregnation time of 24 h under room temperature and calcination time of 3 h under 400℃. Under adsorbent mass/DBT volume of 0.2 g/10 mL, liquid-solid adsorption temperature of 40℃ and adsorption time of 5 h, desulfurization efficiency can reach 28.36%. After continuous adsorption 4 times saturated adsorption sulfur capacity is up to 2.34 mgS/g. Under gas-solid adsorption temperature of 250℃ and adsorption velocity of 6.3 h-1, adsorption sulfur capacity can reach 2.37 mgS/g. The effect of high temperature gas-solid adsorption desulfurization on adsorbent indicates that BET specific surface area, total pore volume and micropore volume of adsorbent have been improved obviously, which show that the gas-solid adsorption desulfurization process has realized the reaming activation of activated carbon simultaneously. The regeneration experiment of toluene solvent shows that the regeneration performance can reach more than 90% after 5 times cycle.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
