Abstract: The release and transformation characteristics of Na/Ca in Zhundong coal under inert atmosphere were studied by using tubular heating furnace based on occurrence modes of Na/Ca containing species. It is found that water soluble Naw firstly transfers to insoluble Nare when the heating temperature is lower than 600℃. As the temperature increases, insoluble Nare transfers back to water soluble Naw. Large amount of Na releases when the temperature is higher than 800℃. Acid soluble Caac firstly decomposes to CaO when the heating temperature is lower than 700℃, and CaO reacts with other minerals to form insoluble Care. As the temperature increases, insoluble Care transfers to acid soluble Caac and water soluble Caw. At the same temperature, the release rate of Ca is lower than that of Na. Moreover, a little amount of acid soluble organic Ca will release when the volatile matter releases.
Abstract: As a typical Zhundong coal, Wucaiwan coal was chosen as the object of the investigation. The combustion ash with coal sample and the reheated ash with ashing sample at 400℃ were prepared in a muffle furnace. K-type thermocouple was used to measure the temperature, XRF and XRD were used to investigate the composition of ash, and the sequential chemical extraction was used to examine the modes of occurrence of Sodium. The results show that the combustion ash and the reheated ash have marked differences in composition and melting points, sodium content in the reheated ash is higher than that in the combustion ash and the melting temperature of the reheated ash is lower than that in the combustion ash. With the increase of temperature, the total content of sodium decreases obviously, the water-soluble and ammonia-soluble sodium decreases rapidly, while the HCl soluble sodium increases first and then decreases and the insoluble sodium increases. The sodium released is mainly soluble. Heating temperature and time have an influence on the releasing of sodium, and the combustion reaction leads to the temperature on particle surface higher than surrounding temperature by 200℃, which is the main cause of releasing more sodium.
Abstract: The gasification reactivity of Shenfu bituminous coal char, rice straw char and their blended char and the synergy behavior in blend were studied using TGA. Additionally, inductively coupled plasma emission spectrometer and scanning electron microscopy coupled with energy disperse spectroscopy were employed to explore the active AAEM transformation characteristics in co-gasification process, so as to correlate and explain the synergy behavior variations during co-gasification. The results show that the addition of rice straw char to coal char was favorable for promoting the overall char gasification reactivity compared with individual coal char gasification. The synergy behavior at different co-gasification conversions changes from the gradually decreasing inhibition effect at the early stage of co-gasification to the gradually enhanced synergistic effect when reaching a turning conversion that is increased at higher gasification temperature. The synergy behavior variations during blended char co-gasification are attributed to the combined effect of active K and Ca transformation characteristics in co-gasification process. Furthermore, the overall synergy behavior of blended char co-gasification is shown as a positive synergistic effect, and it is weakened with the increase of gasification temperature.
Abstract: The coke microcrystalline texture was studied by a high resolution transmission electron microscopy combined with digital image analytical technique (HRTEM-DI). The length, inclination angle and curvature characterization parameters of coke microcrystalline texture may be used to express the size of coke microcrystal, the order degree of microcrystalline lamellar and the order degree of microcrystalline stacking. The developed crystallographic index which is used to characterize the size and order degree could better reflect the effect of coke crystallinity on the coke reactivity.
Abstract: The content of conjugated olefins (double bonds) and olefins (double bonds) in four fractions and five fractions of a FCC slurry was determined by the diene number and bromine number analysis method. UV and 1H-NMR were used to characterize and determine the type and content of olefins in the four fractions and five fractions. The results confirm that the olefin (double bond) and conjugated olefin (double bond) exist in FCC slurry, the contents of olefin (double bond) and conjugated olefin (double bond) are as high as 21% and 6%, the content of conjugated olefin (double bond) in the four components increased in turn, the content of conjugated olefin (double bond) in the five fractions was about 5%, and the content of olefin (double bond) in four components and five fractions all showed a trend of decreasing first and then increasing. At the same time, there are also differences in the content of normal alpha-olefins and internal olefins between different components and different fractions.
Abstract: In this paper, core-shell composite zeolites (HUSY@MFI) were prepared by hydrothermal method. The composite zeolites were characterized by XRD, SEM, N2-adsorption, NH3-TPD and Py-FTIR. The results indicated that HUSY@MFI has both HUSY and MFI structure. Scanning Electron Microscope (SEM) reflects a core-shell morphology of HUSY@MFI. The particles displayed an elliptical sphere structure with scale-like surface. The growth of MFI shell results in a decrease of external acid density and the total acid sites. When the HUSY@MFI was used as catalyst instead of HUSY in hydrolysis of cellulose to glucose in 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), the glucose yield could be significantly improved from 30.9% to 41.3%.
Abstract: In this work, series of Ni/γ-Al2O3 catalysts with or without Cu and Mo components were prepared, characterized and tested for the hydrodeoxygenation of fatty acid methyl esters (FAME) to hydrocarbons. The effects of Cu and Mo loading, impregnation sequence with sequential impregnation and co-impregnation involved and reaction conditions on catalytic performance were investigated. According to the TG data, the spent 20Ni-6Cu/γ-Al2O3 catalyst gives less weight loss than the spent 20Ni/γ-Al2O3 catalyst, which indicates that the addition of copper inhibits the carbon deposits behavior on catalyst surface during reaction. For 20Ni-6Cu/γ-Al2O3 and 20Ni-6Cu-nMo/γ-Al2O3(n=2, 5, 8 and 12) catalysts, NH3-TPD analysis shows that the addition of molybdenum phase has significant impact on the acid sites of γ-Al2O3. When the loading of molybdenum is 5%, a new acid site is observed corresponding to the medium strength acid site. The Cu and Mo modified catalysts demonstrate better catalytic performance than Ni/γ-Al2O3 catalysts. Based on XPS results, Cu in the catalysts exists in the Cu2+ and Mo in the catalysts has two states:Mo4+ and Mo6+, and different impregnation sequences may influence the actual element composition of active phase on the surface of catalysts. In addition, the conversion of FAME and yield of alkane are related to the catalysts prepared with different impregnation sequence. Among all the catalysts, the trimetallic 20Ni-6Cu-5Mo/γ-Al2O3 prepared by sequential impregnation (the former Ni and Cu impregnation, the latter Mo impregnation) exhibits optimal catalytic performance. Under appropriate reaction conditions 350℃, 2.5 MPa, WSHV=2.0 h-1, H2/oil ratio=1250 mL/mL, the conversion of FAME and yield of alkane are 98.4% and 94.2%.
Abstract: The essential role of Co on the MoS2 catalyst in selective hydrodesulfurization (HDS) of FCC gasoline was investigated with ammonium tetrathiomolybdate supported on alumina modified with various amount of Co sulfide. According to the data obtained by XRD, HRTEM, XPS, H2-TPR and Py-FTIR analysis, the Co species could significantly affect the microstructure and composition proportion of the active phase, and thus induced the enormous differences in catalytic properties. The evaluation results demonstrated that the Co atoms tending to form the CoMoS phase as Co/Mo(atomic ratio) < 0.2 could greatly improve the HDS activity, but slightly improve the hydrogenation (HYD) activity of olefins. The spillover hydrogen produced by the formation of Co9S8 phase as 0.2 < Co/Mo(atomic ratio) < 0.6 greatly improved the HDS activity, but showed almost no effect on the HYD of olefins. The excess Co could inevitably form some large size Co9S8 phase as Co/Mo(atomic ratio) > 0.6, which would hinder the mutual contact of the reactants and the active sites, and thus lead to the decrease of the HDS activity and selectivity. The obtained results were useful for developing highly effective hydrotreating catalyst.
Abstract: A series of CuNaY zeolites with different Cu loadings were prepared from NaY by liquid-phase ion exchange (LPIE) method. The microstructure and textural properties of CuNaY zeolites were characterized by XRD and N2 sorption and their adsorption desulfurization performance were evaluated with a model oil containing thiophene by the dynamic adsorption method. Combined with the Py-FTIR and NH3-TPD methods, the amounts of surface acid sites and effective Cu+ species were determined quantitatively and a correlation between the effective adsorption sites and adsorption desulfurization performance of CuNaY zeolite towards thiophene was then established. The results revealed that the surface acidity and the active copper species in Y zeolite can be regulated effectively by controlling the copper loading; an adsorbent provided with abundant effective adsorption sites and excellent adsorption desulfurization performance can be obtained by loading appropriate amount of copper. On the contrary, an excessively high copper loading may promote the formation of polymeric copper species in the cavity of Y zeolite, which leads to a decrease in the number of effective adsorption sites as well as a decrease in the adsorption capacity of CuNaY zeolite towards thiophene.
Abstract: Single phase Co2C catalysts were prepared by carburizing Co with CO at 280℃ and 2 MPa for 48 h. X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), and X-ray absorption spectroscopy (XAS) were carried out to explore the structure and composition of the prepared Co2C samples. The Co2C catalysts were also evaluated in the Fischer-Tropsch synthesis to study their stability and catalytic performance. It was interesting to observe that the CO conversion and the selectivity for C5+ products gradually increased, but the selectivity to methane decreased during the reaction. Comparing the fresh catalysts with used catalysts, it was easy to find that the used catalysts were the mixture of metallic Co and Co2C. The newly generated metallic Co may lead to the changes of CO conversion and product selectivity during the reaction.
Abstract: GaZSM-5 molecular sieve catalysts with different Si/Ga molar ratios were prepared with hydrothermal synthesis method followed by acid exchange and pelletization. The catalyst samples were characterized using XRD, SEM, FT-IR, XPS, ICP, low temperature N2 physical adsorption and desorption, NH3-TPD and Py-FTIR. The catalytic performance in the reaction of methanol to hydrocarbons was evaluated in a fixed bed reactor system. The results indicated that there were two kinds of gallium species, i. e. Ga in the framework Ga and Ga2O3 species on the crystal surface. The catalysts synthesized from SiO2/Ga2O3 (60/1) gel with modest acidity (0.62 mmol NH3/g and the ratio of B/L 4.88) and large mesopore volume of 0.51 cm3/g had the best catalytic stability. Under the same reaction conditions, the lifetime of GaZSM-5 catalyst was 456 h. The acid strength of GaZSM-5 was weaker than that of AlZSM-5, which could inhibit the coke formation. The intercrystalline mesopores of the nano GaZSM-5 crystal improved the diffusion property as well the catalyst stability. The GaZSM-5 lifetime was prolonged by 120 h.
Abstract: Amorphous alloy NiP and its carbon composite catalysts NiP/C and NiP/reduced graphene oxide (RGO) were successfully one-pot synthesized using NaH2PO2 and NiSO4 as phosphorus and nickel source, respectively. The electrocatalysts were characterized with transmission electron microscope (TEM), X-ray diffraction spectrometer (XRD), inductively coupled plasma analysis (ICP) and thermogravimetric analysis (TG), respectively. The hydrogen evolution reactions (HER) performance of the electrocatalysts was evaluated with a linear sweep voltammetry method in both acidic and alkaline solution. Among them, NiP/RGO elctrocatalyst exhibited 89.0 mV onset overpotential and Tafel slope 135.1 mV/decade in acidic solution, as well as 116.1 mV onset overpotential and Tafel slope 122.4 mV/decade in alkaline solution with excellent long-term stability. Results indicated that the NiP/RGO was a very active catalyst.
Abstract: ZnAl-LDHs was prepared by in-situ synthesis method on γ-Al2O3 and the Cu/Zn-Al, Ce/Cu/Zn-Al, Cu/Ce/Zn-Al and Cu-Ce/Zn-Al catalysts were then obtained by wet impregnation method for methanol steam reforming. The catalysts were characterized by XRD, XRF, SEM, N2 sorption, XPS, H2-TPR and N2O titration; the effect of impregnation sequence of Ce on the performance of the Cu/Zn-Al catalysts in methanol steam reforming to produce hydrogen was investigated. The results showed that the impregnation sequence of Ce has a significant influence on the reducibility of resultant catalyst, which subsequently affects the catalytic performance. The Ce/Cu/Zn-Al catalyst exhibits the highest activity; over it, the methanol conversion reaches 100% under 250℃ and with a water/methanol molar ratio of 1.2 and gas hourly space velocity of 800 h-1, which is almost 40% higher than that achieved on the Cu/Zn-Al catalyst.
Abstract: A novel electro-catalytic technique for catalytic methane steam reforming was developed. Based on the conventional industrial Ni-based catalyst, aseries of catalysts, including Ni/γ-Al2O3, Ni-MgO/γ-Al2O3 and Ni-CaO/γ-Al2O3, were prepared using incipient wetness impregnation method with Ni as the active component, γ-Al2O3 as the carrier, and MgO or CaO as the promoter. Experiments were performed to investigate the effects of electric current intensity, reforming temperature, and molar ratio of water vapor to methane (water/carbon ratio, S/C) on CH4 conversion, H2 yield, CO selectivity and catalyst stability. The results indicated that the electro-catalytic technique had good adaptability, and the introduction of electric current could improve the CH4 conversion and increase the H2 yield. Such effects were more intensive at lower reforming temperatures. Among the three catalysts, Ni-CaO/γ-Al2O3 catalyst exhibited the best catalytic efficiency, with the CH4 conversion over 95% under conditions of 4.5 A, S/C of 3, and 700℃. Stability tests of the catalysts showed that the electric current could improve the stability of catalysts and delay the deactivation caused by coke deposition. The characterization results proved that the presence of electric current enhanced the reduction degree of NiO in the catalyst and inhibited NiCx conversion to graphite carbon, resulting the delay of catalyst deactivation caused by carbon deposition over reactive sites.
Abstract: Fe-Ni oxygen carriers (Fe-Ni/BC) were prepared by using pine biochar as a template, and compared with NiFe2O4 oxygen carriers synthesized by sol-gel method. The obtained oxygen carriers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area measurement, hydrogen-temperature programmed reduction (H2-TPR), and thermos-gravimetric redox-cycling (TG-redox). Furthermore, the performance of chemical looping hydrogen generation was investigated in a fixed-bed reactor. The results show that the prepared Fe-Ni/BC is a mixed crystal of Ni0.6Fe2.4O4 and Fe2O3, retaining the framework of biochar and having a macroporous structure. Fe-Ni/BC outperforms NiFe2O4/SG in oxygen release, because of small average particle size, high specific surface area and abundant surface absorbed oxygen. In the fixed-bed tests, Fe-Ni/BC exhibits a better capability of hydrogen production and anti-carbon deposition with the maximum rate of hydrogen production for Fe-Ni/BC, 1.58 times that for NiFe2O4/SG, and the relative concentration of H2 produced by Fe-Ni/BC is more than 99.5%.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
