Abstract: Huozhou (HZ)and Xinghe (XH) lignites were extracted in turn with petroleum ether, carbon disulfide, methanol, acetone and isometric acetone/carbon disulfide mixed solvent to obtain the extracts (E1-E5) and the extraction residues (ER1-ER5), then ER5 was thermally dissolved at 320℃ using methanol, toluene, isometric methanol/toluene mixed solvent and acetone to gain the soluble portions (SPs). The total yields of extraction for HZ and XH are 7.03% and 7.86%, respectively, in which the yield of E3 is the highest. The SPs yield of extraction residue with isometric methanol/toluene mixed solvent is the highest, and the SPs of ER5, HZ and ER5, XH with isometric methanol/toluene mixed solvent reaches 45.76% and 40.14%, respectively. There exist strong adsorption peaks ascribed to aliphatic C-H in the Fourier transform infrared (FT-IR) spectra of E1-E5, while the intensity of adsorption peaks ascribed to C=C, C=O and O-H in the FT-IR spectra of SPs is obviously higher than that of extracts. The gas chromatography/mass spectrometer (GC/MS) analyses show that the oxygen containing organic compounds (OCOCs) in E1-E5 are dominated with alcohols, ethers and ketones, while it is mainly composed of alcohols, phenols and ketones in the SPs, and the strong polar solvents contribute to dissolving the OCOCs in lignites. The adsorption peaks ascribed to associated O-H, C=O and C-O-C in the FT-IR spectra of extraction residues and thermal dissolution residues are weaker than those of raw coals. The X-ray photoelectron spectroscopy (XPS) analyses indicate that the relative content of oxygen forms in XH and HZ is C-O > C=O > COO-, and the relative content of C-O and COO-in HZ is higher than that in XH.
Abstract: Using the Forcite module in MS (Materials Studio 2017) software, the energy minimization molecular dynamics simulation was performed on the self-constructed two-dimensional structural model of Fushun oil shale kerogen, and the initial optimized structure of kerogen was obtained through the energy optimization process. Then, molecular dynamics annealing simulations were performed to obtain a global energy optimization configuration, ie a three-dimensional structural model of oil shale kerogen molecules. Based on the density functional theory of quantum mechanics simulation method, a three-dimensional structural model of kerogen dynamics, bond energy, bond level, charge density and other parameters were calculated, and the chemical active sites were analyzed. The microchemical evolution mechanism of kerogen pyrolysis was discussed. And then, the reactivity was predicted.
Abstract: Zigzag carbonaceous model was applied to investigate the heterogeneous reduction mechanism of NO by moderate gasification char through the density functional theory in quantum chemistry method combined with thermodynamics and kinetics. The reaction path of heterogeneous reduction of NO by moderate gasification char were analyzed, and the energy change during heterogeneous reduction, thermodynamic and kinetic analysis were conducted. Research results show that the moderate gasification char is prone to adsorb NO. The process of CO desorption, which provides active sites for NO reduction, is a reaction rate determining step, and need to overcome the maximum barrier(398.03 kJ/mol). The reduction reaction is spontaneous and exothermic reaction in the coal combustion system and takes place in one direction. According to the theory of reaction rate determining step, the progress of the reaction need to overcome the larger activation energy(389.83 kJ/mol), and according to Arrhenius expression, the overall reaction rate is greatly affected by temperature. The higher the temperature is, the faster the reaction rate is, and the more favorable for NO reduction.
Abstract: The influence of pressure (0.1-6 MPa) on the mineral phase of coal char and the carbon crystal structure and the mineral conversion of coal ash were investigated by using the tube furnace at higher temperature and pressure combined with the analysis of X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results indicate that the mineral phase of coal char is not significantly affected by the pyrolysis pressure; while, the average stacking height or the graphitization degree of coal char increases with increasing the temperature and pressure. With respect to functional groups, the pressure has little effect on the structure of organic functional group. Also, it is found that the pressure has little effect on the main mineral phases of coal ash, but it can affect the relative contents of mineral phases, which is mainly due to the varying of combustion temperatures caused by the transition of the ignition mechanism at different pressures. The effect of temperature on the mineral transformation is more significant than that of pressure.
Abstract: Three common alkali-based materials, NaOH, Na2CO3 and NaHCO3, were utilized to explore their dechlorination performance in a simulated coal-fired flue gas. The results show that the dechlorination efficiency increases along with the enhancement of alkaline intensity. As the Na/Cl molar ratio reaches 5.8, 7.1 and 8.7, respectively, the dechlorination efficiency of all the three alkalis (NaOH, Na2CO3 or NaHCO3) exceeds 70%. The SO2 of high concentration in flue gas has competitive effects on dechlorination. With the increase in SO2 concentration, the dechlorination efficiency drops linearly. The influence of SO2 concentration on the dechlorination efficiency is almost identical regardless of different alkali-based materials. For per 100 mg/m3 augment in SO2 concentration, the dechlorination efficiency decreases by about 1.4%. NaOH is determined to be the most valuable alkali-based material for industrial application considering the cost and solubility.
Abstract: Based on two kinds of biowastes (penicillin mycelia waste, PMW; herbal tea waste, HTW), the difference of biowastes derived from various sources and their fuel characteristics and combustion behavior after hydrothermal upgrading were investigated with the assistance of XPS, TGA and FTIR analyses. The results show that HTW mainly contains lignocelluloses, while PMW mostly consists of protein and polysaccharides. Although the specific conversion paths of various components are slightly different during hydrothermal process, both the higher heating values (HHV) of biowastes are improved (HTW:from 19.4 to 26.2 MJ/kg; PMW:from 19.1 to 29.3 MJ/kg); meanwhile, the coalification degree of biowastes increases with the growing temperature, even reaching the degree of bituminite at 300℃. In addition, the variation in carbon content and structure reflects that the reaction of devolatilization and aromatization during hydrothermal process can improve not only the fuel characteristics but also the combustion behavior.
Abstract: Two NiMo catalysts using the nanosized zeolite HY-Al2O3 composite (labeled as NYA) prepared by mechanical mixing method and sol-gel method as the support were prepared and characterized by XRD, BET, TPD, H2-TPR, HRTEM and FT-IR spectroscopy. The former catalyst possessed larger pore volume and specific surface area, more acid amount, superior reducibility of metal phase and higher dispersion of edge and corner Mo atoms, and showed higher hydrodesulfurization (HDS) performance. Compared with the former catalyst, the latter catalyst had more MoO3 to be converted to active type-Ⅱ NiMoS phase, possessed higher stacking degree and bigger length of MoS2 slabs, and showed lower active phase dispersion. Although the sol-gel method was beneficial to increase the precursor ratio of type-Ⅱ NiMoS phase, the poor pore structure caused by this method inhibited this advantage and reduced the catalytic activity of the catalyst.
Abstract: The effect of ethylene diamine tetraacetic acid (EDTA) modification on the physico-chemical properties and catalytic performance of silica nanosprings (NS) supported cobalt (Co) catalyst was investigated in the conversion of syngas (H2 + CO) to hydrocarbons by Fischer-Tropsch synthesis (FTS). The unmodified Co/NS and modified Co/NS-EDTA catalysts were synthesized via an impregnation method. The prepared Co/NS and Co/NS-EDTA catalysts were characterized before the FTS reaction by BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), differential thermal analysis (DTA) and thermogravimetric analysis (TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. FTS was carried out in a quartz fixed-bed microreactor (H2/CO of 2:1, 230℃ and atmospheric pressure) and the products trapped and analyzed by GC-TCD and GC-MS to determine CO conversion and reaction selectivity. The experimental results indicated that the modified Co/NS-EDTA catalyst displayed a more-dispersed phase of Co3O4 nanoparticles (10.9%) and the Co3O4 average crystallite size was about 12.4 nm. The EDTA modified catalyst showed relatively higher CO conversion (70.3%) and selectivity toward C6-18 (JP-8, Jet A and diesel) than the Co/NS catalyst (C6-14) (JP-4).
Abstract: A static hydrothermal approach was adopted to synthesize nanosized SiO2-ZSM-5 zeolite in the media of F--OH- with double mineralizers, using tetraethoxysilane, sodium aluminate, and tetrapropylammonium hydroxide as the silicon source, aluminum source, and template agent, respectively. The physical and chemical properties of the synthesized ZSM-5 zeolites were characterized and their catalytic performance was evaluated in the conversion methanol to propene (MTP); the effect of F-/Al2O3 molar ratio on the catalytic performance of synthesized H-ZSM-5 was investigated. The results indicate that an increase in the F-/Al2O3 molar ratio of the synthesis mixture leads to an increase in the surface content of microcrystalline SiO2, accompanying with a decrease in the relative crystallinity, surface area, pore volume, and acid strength and density. With a F-/Al2O3 molar ratio of 12, the SiO2-ZSM-5 zeolite exhibits the best catalytic performance in MTP, with a selectivity of 45% to propene and a propene/ethene (P/E) ratio of greater than 10. It is further hypothesized that the transition state shape selectivity plays an important role in determining the product selectivity in MTP.
Abstract: The transesterification of ethylene carbonate (EC) with methanol to synthesis dimethyl carbonate (DMC) and ethylene glycol (EG) over ZnO, La2O3 and Zn-La mixed oxides were explored. The catalysts were prepared by co-precipitation method and characterized by BET, XRD, TG-DSC, CO2-TPD and Hammett titration. The influence of Zn/La atomic ratio, calcination temperature and reaction parameters (reaction temperature, reaction time, catalyst amount) on the catalytic activity were investigated. The results indicated that the binary Zn-La mixed oxide with Zn/La atomic ratio of 2:1 calcined at 500℃ showed the highest catalytic performance for the title reaction due to its strongest basicity, and the amount of strong basic sites of the catalyst should be responsible for the high transesterification activity.
Abstract: Zinc ferrite (ZnFe2O4) nanoparticles were synthesized by atomic layer deposition (ALD).The structure, magnetic and electronic properties of ZnFe2O4 were investigated by density functional theory (DFT) and atomic thermodynamics methods; the stabilities of ZnFe2O4 (311) surface with six different terminations were considered and the surface energies were related to O and Zn chemical potential corresponding to environment.The results indicate that bulk ZnFe2O4 has a normal spinel structure; it is an antiferromagnetic semiconductor with a band gap of 1.91 eV.Only four out of six possible terminations, that is, O1, O2, Fe2 and Zn2 terminations, can be stable within allowed region.In particular, the O1 termination is stable over a wide range of △μO under Zn-rich conditions (△μZn=0 eV), whereas the O2 termination turns to be most stable in Zn-poor environment (△μZn=-3.88 eV).
Abstract: In this paper, CeO2 nanomaterials with oxygen vacancies and CuO/CeO2 catalysts for hydrogen production from methanol steam reforming were prepared by precipitation and impregnation methods.The influence of different calcination atmosphere on the structure and properties of CeO2 nanomaterials and the hydrogen production performance of methanol steam reforming was investigated.SEM, XRD, BET, H2-TPR, N2O titration and XPS were adopted to characterize the catalyst materials.The results showed that the catalytic activity of CuO/CeO2 catalyst was closely related to the surface area of copper, the strength of Cu-Ce interaction, the number of surface defects and surface oxygen vacancies.When the reaction temperature was 250℃, the molar ratio of water to methanol was 1.2 and the gas hourly space velocity was 800 h-1, the methanol conversion was 100% and the CO concentration in the offgas was 0.87%.
Abstract: The influence of nitric acid treatment on the composition and structure of clinoptilolite (HEU) was analyzed by various characterization techniques, such as element analysis (ICP-AES), N2 physical adsorption, X-ray powder diffraction (XRD), 27Al/29Si MAS NMR and DFT calculation.The Si/Al ratio and BET surface area of Na-K-HEU and NH4-HEU were significantly increased after nitric acid treatment, and meanwhile, their relative crystallinity decreased to below 50% when the concentration of nitric acid reached 4 mol/L, illustrating the severe distortion of zeolite framework.However, the structure of H-HEU was more stable and it could maintain a high relative crystallinity of 94.8% even the concentration of nitric acid reached 6 mol/L.The results of 27Al/29Si MAS NMR indicated that some extra-framework aluminum species appeared in H-HEU and they could protect the framework aluminum from further distortion, whereas this protective effect did not exist on Na-K-HEU and NH4-HEU, as they have little extra-framework aluminum species.It can be further proved that through back-exchanging the H-HEU to Na-HEU and K-HEU, their resistance to nitric acid treatment could be markedly improved.
Abstract: A simple dual-component catalytic system, i.e., Ag(Ⅰ)/(nC7H15)4NBr was applied for the synthesis of various β-oxopropylcarbamates via dual-component coupling of ammonium carbamates and propargylic alcohols under atmospheric pressure.This simple method was proved to be a highly efficient system without the use of ligand, and capable of converting various propargylic alcohols and secondary amines into corresponding organic carbamates.Notably, quantitative conversion of CO2 was achieved, thus improved the efficiency of CO2 utilization.
Abstract: A series of CexZr1-xO2 catalysts with different Ce/Zr molar ratios were prepared by sol-gel method and characterized by X-ray diffraction (XRD), nitrogen sorption, Raman spectra, oxygen storage capacity (OSC), thermogravimetry (TG) and pyridine adsorption infrared (Py-FTIR) spectra; the performance of CexZr1-xO2 in catalytic wet air oxidation (CWAO) of phenol was investigated. The results demonstrate that CexZr1-xO2 solid solution is formed by doping ZrO2 in CeO2 and the OSC value of CexZr1-xO2 increases with an increase in the content of ZrO2. In comparison with pure CeO2, CexZr1-xO2 solid solution has more Lewis acid sites. The catalytic activity of CexZr1-xO2 is related to both OSC and surface acidity; the Lewis acid sites are favorable for the complete oxidation of phenol, whereas high OSC may promote the carbonaceous deposition that leads to catalyst deactivation. The Ru/Ce0.75Zr0.25O2 catalyst exhibits high activity in phenol oxidation; after reaction for 5 h at 160℃ and 2 MPa O2, phenol conversion and total organic carbon (TOC) rate reach 100% and 99%, respectively.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
