Abstract: In order to utilize semi-coke resources efficiently and select the suitable dispersant to improve the performance of slurry prepared by semi-coke, the effects of different dispersants (sodium humate, sodium lignosulfonate, sodium dodecyl sulfonate and a self-made itaconic acid dispersant IPMS) on the pulping property of semi-coke slurry were studied. The structure parameters of dispersant and the interaction energy between semi-coke and dispersants were calculated by the software-Material Studio (MS) and compared with experimental value. The results show that the addition of dispersants can effectively reduce the surface tension of liquid and increase the electronegativity of semi-coke particles, enhancing the electrostatic repulsion between particles and making the slurry more stable. The self-made itaconic acid dispersant IPMS has a better effect on the property of semi-coke water slurry under the same preparation conditions. The apparent viscosity is 625 mP·s when the shear rate is 100 s-1, the water-liberating rate in 7 d of slurry is only 2.38% and there is no hard precipitation. The adsorption simulation indicates that the oxygen atom of the dispersant approaches to the hydroxyl side of the semi-coke and makes charge transfer, and the order of activity of four dispersants is IMPS > SH > SLS > SDS. The interaction between IMPS and the semi-coke leads to a strong adsorption, which is consistent with the experimental results. It is proven that the performance of dispersants can be evaluated by quantum chemical calculation combined with experimental data, providing a theoretical basis for the preparation technology of slurry fuel as well as the design and development of new reagents.
Abstract: In order to reveal the release mechanism of chlorine(Cl) in low rank coal during pyrolysis process, a low rank coal from northern Shaanxi was pyrolyzed at different temperatures, particle sizes and heating rates in a tubular reactor and a Thermo Gravimetric-Infrared-Mass spectrometry (TG-IR-MS) to investigate the transferring and release characteristics of Cl during pyrolysis process. The dynamic model of Cl transferring and release was built based on the process of coal pyrolysis. The results show that the chloric species from the pyrolysis of low rank coal is HCl and little Cl2, and the temperature strongly influences the release rate of Cl during pyrolysis in the tubular reactor. With the pyrolysis temperature increasing from 300 to 800 ℃, the release rate of Cl increases significantly, reaching to 49.5% at 800 ℃, while the fraction of Cl in the char decreases and the fraction of Cl in coal tar and pyrolysis gas increases gradually. The release rate of Cl has a maximum of 35.8% as the particle size is 3.0-4.0 mm. The particle size also affects the distribution of Cl in pyrolysis products. Moreover, increasing the heating rate is beneficial to the devolatilization, and the release rate of Cl in coal changes obviously as the heating rate is 15-25 ℃/min, but much higher heating rate will result in the decrease of the release rate of Cl in coal. Most Cl species in the coal tar is in form of water-soluble inorganic chlorides, and therefore the ultrapure water can present a better performance to remove chlorides. The release activation energy of chlorine in pyrolysis is about 20 kJ/mol.
Abstract: Four different kinds of ionic liquids(ILs), namely, 1-butyl-3-methylimidazolium bromide([Bmim]Br), 1-butyl-3-methylimidazolium tetrafluoroborate([Bmim]BF4), 1-butyl-3-methylimidazolium hydro-sulfate([Bmim]HSO4), and 1-butyl-3-methylimidazolium dihydrophosphate([Bmim]H2PO4) were selected to add to the H2O2 solution (30%), respectively, to obtain four mixed solutions. Then, two kinds of deashed high-sulfur coal (LS, QX) desulfurization experiments were tested with above mixed solutions under mild conditions, respectively. The contents of different sulfur forms in coal samples before and after desulfurization were determined by wet chemical method, and the coal samples before and after desulfurization were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and thermogravimetric (TG). The results show that the addition of ionic liquids can make the H2O2 oxidation desulfurization ability enhance, and pyrite sulfur and organic sulfide sulfur in coal are obviously removed. After treated by the ILs/H2O2 system, the small size particle decreases, the space among the particles increases, and the pits on the coal surface become obvious. Moreover, the thermogravimetric test results show that the total weight loss of the coal sample treated by the ILs/H2O2 system increases and the peak temperature of some volatile substances lowers.
Abstract: A series of NiMo/Al2O3-USY catalysts with different MoO3 contents were prepared through incipient wetness method and further modified with NH4F. The NiMo/Al2O3-USY catalysts were characterized by XRD, XPS, HR-TEM, NH3-TPD, H2-TPR and N2 adsorption and their catalytic performance in the hydrocracking of low-temperature coal tar (LTCT) was investigated in a 200 mL fixed-bed reactor. The results indicate that the appropriate MoO3 content is 15% (mass ratio); higher MoO3 content may lead to the agglomeration of active metals on the support, although it has little influence on the sulfidation degree of Mo species and the conversion of coal tar upon hydrocracking. In addition, the amount of strong acid sites and pore diameter decrease gradually with a further increase in the MoO3 content, which is disadvantageous for deep hydrocracking. The modification of USY zeolite with NH4F solution can enlarge the average pore diameter of resultant NiMo/Al2O3-USY catalysts and then improve the residue conversion of coal tar. However, the amount of strong acid sites decreases obviously when the concentration of NH4F solution exceeds 0.6 mol/L, which may lead to an increase of the sulfur content in the hydrocracking product. Over the NiMo/Al2O3-USY catalyst modified with 0.6 mol/L NH4F solution, the residue conversion of coal tar reaches 87.65%; the sulfur contents in the gasoline fraction (< 180 ℃) and diesel fraction (180-320 ℃) are 5.96 and 34.98 mg/kg, respectively.
Abstract: The catalytic co-pyrolysis of wet sewage sludge and wheat straw for hydrogen-rich gas production was experimentally investigated in a fixed bed reactor with Ni/Zr-MOF catalyst. The Ni/Zr-MOF catalyst was characterized by ultimate analysis, XRF, TG, XRD, SEM and BET. The effects of reactor temperature, straw content and Ni loading on the composition and yield of gasification gases were explored. The experimental results indicate that the mesoporous Zr-MOF support particles are octahedral with a specific surface area of 805.93 m2/g and an average pore diameter of 20.14 nm. The Ni/Zr-MOF catalyst has high thermal stability and catalytic activity. Compared with the pyrolysis without catalyst, the H2 yield increases significantly from 0.39 mol/kg to 12.65 mol/kg using Ni/Zr-MOF catalyst at 500 ℃. After reuse, the carbon deposits are formed on the surface of catalyst. With the increase in reactor temperature, the catalytic activity decreases gradually due to the agglomeration of the catalyst. Therefore, the Ni/Zr-MOF catalyst is suitable for catalytic pyrolysis of biomass at lower temperature.
Abstract: Recently, organosulfur removal from liquid petroleum fuels is very significant aspect of environment protecting and fuel cell requests. Therefore, improved approaches to remove sulfur are still essential. In the present work, a simple catalytic oxidative desulfurization (CODS) system for Iraqi gasoil fraction has been successfully developed using CuO-ZnO nanocomposites as catalysts, and H2O2 as oxidant under microwave irradiation. The main reaction parameters influencing sulfur conversion including microwave power, irradiation time, catalyst dosage and H2O2 to gasoil volume ratio have been investigated. The CuO-ZnO nanocomposites was synthesized with different weight ratios and characterized by XRD, FE-SEM, AFM and BET surface area methods. The results reveal that, high sulfur conversion (93%) has been achieved under suitable conditions of microwave CODS as follows:microwave power of 540 W, irradiation time of 15 min, catalyst dosage of 8 g/L (0.4 g), and H2O2:gasoil volume ratio of 0.3. The catalyst reusability shows that the synthesized catalyst can be reused five times without an important loss in its activity.
Abstract: Developing cost-effective electrocatalysts for oxygen evolution reaction (OER) in basic media is critical to hydrogen production from renewable energy. Herein, in-situ electrodeposited flower-like NiFeOxHy and NiFeOxHy/rGO composite electrocatalysts on Ni foam for OER are reported. The active sites of the flower-like electrocatalysts are increased significantly due to the enhanced NiFeOxHy surface areas and numerous exposed layered edges and edge defects. Reduced graphene oxide (rGO) has been introduced to fabricate NiFeOxHy/rGO composite film, further improving the conductivity and OER performance of the flower-like NiFeOxHy. The optimized NiFeOxHy/rGO exhibits superior OER performance with a Tafel slope of 29.11 mV/decade, an overpotential of 200 mV at 10 mA/cm2 in 1 mol/L KOH and favorable long-term stability.
Abstract: A series of MoS2/TixOy catalysts were prepared by a one pot solvothermal synthesis method and the effects of solvent, sulfur source, molybdenum source and titanium subdioxide conductive agent on the electrocatalytic activity of MoS2/TixOy in hydrogen evolution from water splitting were investigated. The results showed that the crystal structure of MoS2/TixOy catalyst as well as its catalytic performance is greatly influenced by the solvent, sulfur source, molybdenum source and titanium subdioxide conductive agent. Water, sulfur and molybdenum sources which can produce ammonium ions via hydrolysis, and the conductive agents are beneficial to improving the hydrogen evolution activity of the MoS2/TixOy catalyst in water splitting. In particular, with water as the solvent, thioacetamide and ammonium molybdate as the sulfur and molybdenum sources, respectively, the MoS2/TixOy catalyst with the highest hydrogen evolution activity was obtained; it needs only 280 mV overpotential to reach 10 mA/cm2 current density in the electrolysis of water.
Abstract: The synthesis of isobutanol from syngas is a such complicated process, and the relationship between catalyst properties and isobutanol formation is still not fully understood yet. Coprecipitation is a common preparation method for solid composite oxides synthesis, by which, the catalyst will have high dispersion, strong interaction. However, it also remains many factors affecting the preparation process. In this work, the effect of precipitation temperature on the properties of catalysts at the beginning of precipitation reaction was investigated, and the relationship between the properties of catalysts and the formation of isobutanol was studied by different characterization methods in combination with the catalysts evaluation results, in order to further improve the formation mechanism of isobutanol. The results revealed that at lower precipitation temperature (30 ℃), the CuO was easier to be reduced due to the better Cu dispersion and stronger interaction in CuO and ZrO2, at the same time as the CuO and ZrO2 could form better solid solutions at this condition. Meanwhile, hydroxyl groups were formed on the catalyst surface at lower precipitation temperature during the catalyst preparation process, therefore these hydroxyl groups could react with CO to form surface C1 species, which further promoted the growth of carbon chain and improved the selectivity of isobutanol. With the increase of precipitation temperature, CuO particles were enlarged; CuO-ZrO2 solid solution was gradually destroyed; the interaction in CuO and ZrO2 was weakened; and the content of surface hydroxyl was decreased, resulting in a decrease of surface C1 species and isobutanol selectivity. Among all the catalysts, the highest selectivity of isobutanol (38.7%) was obtained over the CLZ-30 catalyst.
Abstract: High-silicon ZSM-5 zeolite was treated with NaOH solution to investigate the effect of modification on benzene-methanol alkylation. The physicochemical properties of the samples were characterized by XRD, SEM, XRF, NH3-TPD, TPO, and BET. The results showed that NaOH treatmeng removed the molecular sieve silicon species and the surface deposits, revealed more acid sites, formed certain amount of mesopores, which affected the alkylation performance of benzene-methanol. When the NaOH treatment amount was 2.4 mmol/gcat, the conversion rate of benzene in the alkylation reaction reached 38% at a liquid volume space velocity of 85 h-1, which was nearly 16% higher than that before treatment, and the modified catalyst had low carbon deposition and better stability.
Abstract: A series of nanorod CeO2(x)-NiO composite oxides catalysts with different Ce/Ni molar ratios have been synthesized by hydrothermal method. Their morphology and structure were characterized by N2 sorption-desorption, XRD, TEM, Raman spectra, H2-TPR and XPS. The effects of Ce/Ni molar ratio on the morphology and catalytic activity of CeO2(x)-NiO composite oxides catalysts for CO preferential oxidation (CO PROX) in hydrogen-rich stream were studied. TEM results indicate that nanorod CeO2(x)-NiO composite oxides catalysts with different sizes can be obtained by adjusting Ce/Ni molar ratio. H2-TPR results show that introduction of NiO into CeO2 enhance the redox ability of CeO2(x)-NiO composite oxides catalysts. Raman spectra and XPS results indicate that CeO2(x)-NiO composite oxides catalysts with low nickel content have much more active oxygen species and oxygen vacancies, which are beneficial to improve its catalytic performance. CeO2(0.89)-NiO nanorod catalysts with low nickel content exhibits the highest activity and CO2 selectivity, the CO conversion is 100% and the CO2 selectivity is about 52% in the reaction temperature range of 170-220 ℃ for CO PROX in hydrogen-rich stream.
Abstract: Nd-Co3O4 catalysts were prepared by hydrothermal and co-precipitation methods to catalyze the decomposition of N2O. The catalysts prepared by hydrothermal method showed higher activity. Among the hydrothermal Nd-Co3O4 catalysts, the catalyst with Nd/Co molar ratio of 0.01 had higher activity. 0.01Nd-Co3O4 catalyst was then impregnated by K2CO3 solution to prepare K-modified catalyst. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electrons microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD). The results show that Nd-Co3O4 and K-modified catalysts exhibit spinel structure. In contrast to bare Nd-Co3O4, the K-modified catalyst with higher activity is due to its weaker strength of Co-O bond and easier desorption of surface oxygen species. In addition, over 90% conversion of N2O can be reached over 0.02K/0.01Nd-Co3O4 at 350 ℃ for 40 h under the co-presence of oxygen and steam in feed gases.
Abstract: The CeO2, WO3 and CeO2-WO3 (donated as CW) catalysts were prepared by in-situ self-assembly method and used for the low-temperature selective catalytic reduction (SCR) of NOx with NH3. The results showed that CW catalysts possessed the most microspore and maximum pore volume and larger specific surface area with the addition of WO3, resulting in the improvement to the catalytic performance. Besides, the interaction of Ce and W was improved by the introduction of WO3, which could increase the amount of Ce3+ and Oα. Meanwhile, the enhancement of weak and medium strong acid sites was caused by the introduction of WO3. Thus, CW catalyst showed the best SCR activity and its NOx conversion at the value of 100% maintained in a wide temperature window ranging from 250 to 400 ℃.
Abstract: With unmodified and modified Al2O3 as the support, a series of Mn-Ce catalysts were prepared by impregnation method and characterized by XRD, BET, NH3-TPD, H2-TPR and FT-IR. The catalytic performance in the NH3-SCR of NOx was investigated. The results show that the sulfuric acid modification to the support decreased the metal dispersion and weakened the oxidization property of the catalyst, increased the concentration of acid sites, especially, B acid sites. Besides, the optimum temperature window ranges for SCR of the modified catalyst moved to higher temperature and broadened, and increased with the increase of modified liquid concentration. The unmodified catalyst and the catalyst modified by 0.2 mol/L solution had same SCR reactivity within the temperature range of 200-250 ℃. However, the modified catalyst showed the best resistance to SO2 and H2O and presented 70% NO conversion at 250 ℃.
Abstract: A series of La1-xRbxMnO3 perovskite catalysts (x=0, 0.1, 0.2, 0.3) were prepared by solvothermal method and characterized by means of XRD, FT-IR, SEM, XPS and H2-TPR; their catalytic performance in the simultaneous removal of NO and soot was investigated in a fixed-bed micro-reactor. The results show that the La1-xRbxMnO3 catalysts have a single perovskite structure and the Mn species exist in the form of Mn3+ and Mn4+. In comparison with LaMnO3, when La3+ is partially substituted by Rb+, more high-valence Mn4+ and oxygen vacancies are formed in La1-xRbxMnO3, which can improve the redox properties and enhance the catalytic performance of La1-xRbxMnO3. With the increase of Rb+ content in La1-xRbxMnO3, the conversion of NO increases and the soot combustion temperature decreases. For NO and soot removal over La0.7Rb0.3MnO3, x=0.3, the peak CO2 formation temperature (tmax) is 430 ℃, with a selectivity of 99.0% to CO2; at 429 ℃, the maximum conversion of NO reaches 59.7%.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
