Abstract: Carbon structure parameters were obtained accurately, if the NOE effect of carbon nucleus has been eliminated in13C CP/MAS/TOSS NMR test. This study has investigated different model compounds NOE effect intensity. And the results show that there is an obvious carbon structure error between the fitting test value and theoretical value in the different model compounds. The aliphatic carbon error is 25%-125%, and the aromatic carbon is 4%-50%, the NOE effect has great influence in solid state NMR. Therefore, the nonlinear regression equation was obtained by regression analysis of the measured and theoretical values of the model compound aliphatic and aromatic carbon. And this equation was used to calibrate the carbon structure of 9, 10-dimethylanthracene. It is found that after calibration the error between the measured value and the theoretical value of the modified aliphatic is reduced from 119.60% to 7.84%. The error of the aromatic carbon is reduced from -17.10% to 1.11%. And the error is within 10%. Then, the carbon structural parameters of different coal are calibrated by the regression equation. It is found that the H/C error of different coal is 45%-53% compared with elements analysis, and the calibration error is only 4%-13%, which is consistent with the results of elemental analysis. It indicated that the nonlinear regression equation could easily and precisely correct the solid state NMR carbon nuclear NOE effects and also provides new technical support for analysis of carbon structure in coal.
Abstract: Three ashes containing V and Ni were preparation for the study. CaO addition and coal ash blending were chosen for regulation of high temperature flow properties. The regulation mechanism was explored by XRD, SEM-EDX and ternary phase diagram analysis. The results show that karelianite and Ni are main refractory matters in petroleum coke ash at high temperature. CaO addition and coal ash blending decrease the liquid temperatures of ash components except V and Ni, which reduces the ash fusion temperatures. When the contents of V and Ni are fewer than 30% in ash, CaO can obviously decrease the fusion temperature of ash, and the viscosity-temperature property becomes crystal type. When the contents of V and Ni are higher than 30% in ash, coal ash blending is an effective method to decrease the fusion temperature. In this condition, 5% of coal ash blending ratio is required, and its viscosity-temperature property is suitable for slag tapping, but when the coal ash proportion is 10% the viscosity-temperature property of ash becomes crystal type for the precipitation of vanadium-rich spinel, which cannot meet the requirement of slag tapping.
Abstract: The occurrence modes of sodium species and corresponding content distributions in sodium-rich coals were investigated through a series of analytical methods. The results indicate that for the vast majority of coals sodium are mainly in the form of water-soluble form, then organic form, and the content of insoluble form is negligible. Among them, the water-soluble sodium is mainly presented as nitratine (NaNO3), halite (NaCl) and hydrated ion (Na·xH2O). The organic sodium is mainly presented as carboxyl sodium (-COONa), while the insoluble sodium mainly occurs as albite (NaAlSi3O8).
Abstract: Combustion experiment of Xinjiang coal with high sodium content was carried out in a horizontal tube furnace at 400-1 100℃. The occurrence of sodium in coal and ash was analyzed by sequential extraction method to study the release and transformation characteristics of sodium, especially the effect of H2O(g) and SO2(g) at 700℃ and 1 100℃. The results show that, the release ratio of sodium in coal increases gradually with the increase of temperature. The sodium in organic form vaporizes first, followed by water-soluble inorganic sodium, while the inorganic sodium in the form of aluminosilicate is difficult to vaporize due to high thermal stability. At lower temperature (700℃), H2O(g) has a negative effect on the volatilization of sodium, while at higher temperature (1 100℃), the reductive atmosphere formed by the reaction of char and H2O(g) promotes the volatilization of sodium. When the proportion of H2O(g) is larger than 20% in inlet gas, the promotion effect of H2O(g) is weakened. SO2 can inhibit sodium volatilization, while the inhibiting effect of SO2 becomes less significant as the temperature increases from 700℃ to 1 100℃. In the presence of both H2O(g) and SO2, the sodium volatilization at 700℃ is inhibited. The combination effect of H2O(g) and SO2 at 1 100℃ depends on its concentration. Under the atmosphere containing 20%H2O and 2.0×10-3 SO2 the total volatilization ratio of sodium increases from 86% to 87.1%.
Abstract: The Zhundong high sodium coal was hydrothermally upgraded at 150-350℃ in an autoclave. The inductively coupled plasma mass spectrometer (ICP-MS), nitrogen adsorption isotherm (BET) and X-ray diffraction (XRD) were used to investigate the changes of coal properties and the impacts on the CO2 gasification characteristics. The results indicate that the coal quality is increased after the hydrothermal upgrading. The removal effect of sodium is obvious, reaching to more than 95% at 300-350℃. The pore structure of the chars changes significantly, the specific surface area and total pore volume increase initially at 150-300℃ and then decrease at 300-350℃. The crystalline structure tends to be aromatic and graphitized, and the chemical structure becomes dense, orderly and stable. Additionally, the gasification reactivity exhibits a decreasing trend, especially for the chars treated at 300-350℃. The CO2 gasification reactivity during the process of hydrothermal upgrading is comprehensively influenced by different factors containing coal rank, sodium content, physical pore structure and chemical microcrystalline structure.
Abstract: The influences of gasification temperature (800-950℃) and blending ratio (3:1, 1:1, 1:3) on the isothermal CO2 co-gasification reactivities of Shenfu bituminous coal char (SF char) and HTC char were investigated using an atmospheric thermogravimetric analyzer (TGA). Moreover, the activation energy of char gasification and its influence factors were explored. The results show that the greater surface area and the higher ash content are the main reasons for the high gasification reactivity of HTC char. The reactivities of mixtures with low HTC char proportion are more sensitive to temperature at low temperature range. The activation energy increases with the increase of carbon conversion, and the activation energy correlates well with the blending ratio and the molar ratio of active (K+Na)/Ca in the char.
Abstract: Combustion experiments of Changzhi coal at 550-1 000℃ were conducted in a tube furnace reactor in air and O2/CO2, respectively. The XRF, XRD etc. were employed to study the characteristics of raw coal and its demineralized coal. Effects of mineral matter in coal on combustion characteristics and release of SO2 and NOx during combustion were investigated using TG-DTG and Antaris-IGS. The results show that ignition and burnout temperature of the demineralized coal are lower than those of raw coal. In O2/CO2 the ignition and burnout temperature of raw coal and the demineralized coal are all higher. This shows that when oxygen concentration is 20%, the coals are easier to ignite and burnout in air. Besides that, SO2 emission of the demineralized coal is higher than that of raw coal; while NOx emission is opposite. For raw coal, SO2 emission is higher when combusted in O2/CO2; while for the demineralized coal, it is opposite. During combustion in O2/CO2, NOx emission is always lower whether for the raw or the demineralized coal.
Abstract: The molecular structures of Fushun and Maoming kerogen were constructed based on the characterization techniques such as solid-state13C nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and ultimate analysis. Self-build kerogen models were modified on the basis of chemical bond concentration, chemical bonds concentration of experiment data and molecular structure match well, therefore constructed models have been proved to be accurate and reasonable from the perspective of chemical bonds. From the data of self-build and selected kerogen models, the relationship between metamorphic degree of oil shale kerogen with concentration of chemical bonds and energy density were studied. With the increase maturity of oil shale kerogen, the chemical bonds concentration between aromatic carbon and aromatic carbon, aliphatic carbon, hydrogen atom increase, the chemical bonds concentration between aliphatic carbon and aliphatic carbon, hydrogen atom decrease. Among them the chemical bonds concentration between the aromatic carbons, and that between aliphatic carbon and hydrogen atom change obviously. Valence electron energy and non-bond energy are two parts that make up total energy, being the steady chemical energy of oil shale kerogen and increase with increase of its metamorphic degree.
Abstract: On the basis of rapid pyrolysis of two antibiotic mycelial wastes (AMWs), viz., penicillin mycelia waste (PMW) and terramycinmycelial waste (TMW), in a horizontal tubular quartz reactor, evolution of nitrogen functionalities and their relation to NOx precursors were investigated with the help of XPS and chemical absorption-spectrophotometry methods.The results indicate that inorganic-N (N-IN) and amide-N/amine-N/amino-N (N-A) are two kinds of nitrogen functionalities in the raw AMWs samples, determining the predominance of NH3-N among NOx precursors. N-A is found to be the main one with the proportion of 81.1% and 59.0% for PMW and TMW, respectively. At low temperatures, the decomposition of N-IN and the conversion of N-A mainly occur at 150-250℃ and 250-450℃, respectively, which are two routes for most NH3-N with yields of 20.9% (PMW) and 25.6% (TMW). While HCN-N is produced with a small amount less than 2%, having no relationship with the characteristics of nitrogen functionalities in fuels. Besides, pyridinic-N (N-6) and pyrrolic-N (N-5) are also formed and then converted with peak values at 350-400℃. At high temperatures, the conversion of N-6 and N-5 is prevailing, leading to the basically equal increments on NH3-N and HCN-N. Simultaneously, a minor amount of more stable quaternary nitrogen (N-Q) and N-oxide (N-X) is produced. Typically, due to the rapid decomposition of N-IN and labile N-A at low-temperature pyrolysis, nitrogen removal can reach up to 40% while energy loss can be controlled within 25% when pyrolyzing at 250-300℃. As a result, low-temperature pyrolysis could be an effective method for nitrogen removal whereas preserving the energy in AMWs.
Abstract: Ultralight and nitrogen doped graphene aerogels (UNGAS) are developed by a hydrothermal method in the presence of graphene, dopamine (DA) and L-arginine. Analysis shows that DA can functionalize the graphene surface and also embed nitrogen atoms onto the graphene sheets upon pyrolysis, and the values of pH on the hydrothermal fabrication of UNGAS have great in fluence on the formation of UNGAS. By adjusting the amount of L-arginine and dopamine in the precursor mixture, UNGAS with a density as low as 2.54 mg/cm3 can be prepared. The UNGAS show high absorption capacity for various oils due to low density, N doping and large surface area.
Abstract: The effects of glucose on the morphology of the microspheres of zinc oxide were first studied, and then 5% NiO/ZnO microspheric adsorbents were prepared by impregnation method and hydrothermal synthesis. The morphology and structure of NiO/ZnO microspheres were analyzed by N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD) methods, and the effects of the preparation method of NiO/ZnO microspheric adsorbents on the physicochemical properties were examined. Furthermore, Ni/ZnO microsphere adsorbent was prepared by reduction with H2, over which the performance of adsorption desulfurization was tested in a fixed bed reactor by using thiophene as the sulfur compounds in model gasoline.The results show that the specific surface area and pore volume of the NiO-ZnO microspheric adsorbents prepared by hydrothermal method are as high as 40.45 m2/g and 0.096 cm3/g, respectively, in contrast to the ones prepared by the impregnation method, and the composite Ni-ZnO microspheric adsorbents exhibit a favorable desulfurization activity. Under the conditions including a temperature of 350℃, a pressure of 1.0 MPa, a volume space velocity of 6 h-1, and a hydrogen to simulated oil volume ratio of 60, the sulphur contents in simulated oil decrease from 1.5×10-4 to less than 10-5. Also, the adsorbents boast a good regeneration capacity and a potential application value in industry.
Abstract: Al-ITQ-13 molecular sieves, viz., SiGeAl-ITQ-13 and SiAl(B)-ITQ-13, were prepared by the direct hydrothermal synthesis and post-synthesis methods and characterized by XRD, 27Al MAS NMR, NH3-TPD, Py-FTIR and SEM; their catalytic performance in the conversion of methanol to hydrocarbons (MTH) was investigated. The results indicated that two Al-ITQ-13 samples have high crystallinity with a slice-like morphology. In comparison with ZSM-5, Al-ITQ-13 as a catalyst in MTH exhibits higher selectivity to propene, higher propene/ethene (P/E) ratio and longer catalytic lifetime. Moreover, as the amount of strong acid sites on SiAl(B)-ITQ-13 is decreased by post-synthesis, SiAl(B)-ITQ-13 exhibits better catalytic performance in MTH, in comparison with SiGeAl-ITQ-13 obtained by direct hydrothermal synthesis.
Abstract: With sodium silicate and sodium aluminate extracted from fly ash as the raw materials, NaP zeolite was prepared by hydrothermal synthesis method; the synthesis parameters such as crystallization time, temperature and the ratio of silicon/H2O were optimized via orthogonal tests. The method to regulate the crystal growth process was proposed through controlling the steric hindrance effect. The NaP zeolite was characterized by XRD, FT-IR, SEM and N2 sorption; the effect of steric hindrance on the crystal phase and grain size was investigated. The results show that the morphology and grain size of NaP zeolite can be effectively regulated by introducing steric hindrance agents into the hydrothermal reaction system. The strength of steric hindrance effect of various agents follows the order of ring structure > linear structure, long chain structure > short chain structure. The adsorption test suggests that removal rate of Zn2+ exceeds 99.8% for NaP zeolite under the optimal adsorption conditions.
Abstract: In order to explore the effects of Ba/Ce ratio on the NOx storage performance of the catalyst, a series of Pt/xBa-(30-x)Ce/γ-Al2O3 (x=10, 15, 20, x is a mass fraction) NSR catalysts were prepared by a modified sol-gel method combined with an impregnation method, and their properties were characterized by means of X-ray diffraction (XRD), specific surface area analysis (BET), temperature programmed reduction of H2 (H2-TPR) and temperature programmed desorption of NO (NO-TPD). The results indicate that Ba mainly exists in the form of BaCO3, and CeO2 is present in the amorphous form. With the increase of x value, CeO2 grain size decreases firstly and then increases. With the increase of Ce content, the high temperature reduction peak has a similar tendency with that of CeO2 grain size. The NO-TPD results show that the NOx adsorbed on the surface of the catalyst has a better thermal stability with the temperature below 350℃. The effects of Ba/Ce ratio on the NOx storage performance were investigated by a simulated gas test platform. The results show that the NOx storage capacity of the Pt/15Ba-15Ce/γ-Al2O3 catalyst has a maximum value of 47.1%, and the NOx breakthrough time is 7 min. When the storage process completes, the NO2/NOx ratio of Pt/15Ba-15Ce/γ-Al2O3 catalyst is 28%. The NOx storage efficiency increases firstly and then decreases, and different Ba/Ce ratios have great influences on the storage path of the catalyst. The catalyst presents excellent NOx storage performance when the Ba/Ce ratio is 1.0. The experimental results provide a reference for the optimal design and application of NSR catalyst in the field of diesel exhaust after-treatment system.
Abstract: ZnCr2O4-ZnO composite photocatalyst with heterogeneous structure was synthesized by grinding hydrothermal method and characterized by TG-DTA, XRD, SEM, HRTEM, DRS, and N2 absorption; its photocatalytic activity in H2 production was evaluated by using oxalic acid as the sacrificial agent under simulated sunlight irradiation and compared with those of the ZnCr2O4-ZnO samples prepared by coprecipitation, urea reflux and urea hydrothermal methods. The results indicate that Zn-Cr precursors prepared by four methods show a certain hydrotalcite structure; the catalyst samples prepared at 500℃ are spherical nanoparticles, but different in agglomeration status, specific surface area and pore structure parameters. The ZnCr2O4-ZnO nanoparticles prepared by a grinding hydrothermal method exhibits the optimized photocurrent response and photocatalytic activity; the yield of hydrogen production is 0.956 mmol/(h·gcat), which is 2.3, 1.5 and 3.0 times higher than that of the catalyst samples prepared by coprecipitation, urea reflux and urea hydrothermal methods, respectively. On the basis of these results, a possible mechanism for the hydrogen production over ZnCr2O4-ZnO composite photocatalyst with heterogeneous structure was then proposed.
Abstract: Bio-cathode microbial fuel cells (MFCs) were modified with MnO2/rGO and Pt/C; the effects of cathode catalyst modification on the performance of microbial fuel cells in electricity production and aged landfill leachate treatment were investigated. The results show that the MFC modified with MnO2/rGO can significantly enhance the electricity production and the removal of contaminants. The MFC modified with 1.0 mg/cm2 MnO2/rGO exhibits a harvest voltage of 372 mV, power density of 194 mW/m3, chemical oxygen demand removal rate of 58.68%, and ammonia removal rate of 76.64%; such a performance is similar to that modified with Pt/C, but the cost is greatly reduced.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
