Abstract: The carbon content in fine slag during entrained-flow gasification is very high, at present, most of the fine slag was disposed by landfill. It is expected to provide a favorable technology by adding the fine slag to the circulating fluidized bed boilers to participate in combustion reaction. In this study, the gasification fine slags generated from GE, OMB and GSP gasifier, which are typical gasification processes in Ningdong energy and chemical base, was selected for investigation. The structural features and combustion reactivity of the residual carbon in the gasification fine slag were systematically studied by physical adsorption apparatus, laser Raman spectrum and thermogravimetric analyzer. The results showed that the materials in the original gasification fine slag could be divided into cohesive spherical particles, porous irregular particles and isolated large spherical particles, while the acid-washed gasification fine slag was mostly composed of loose fine particles and porous irregular massive particles. Additionally, the particle size of the residual carbon was clustered to 4–8 nm, and the specific surface area and active sites of that decreased orderly as follows: GE>OMB>GSP. The order degree of the residual carbon structure in GE slag was the lowest, and the amorphous carbon structure in it was the highest, while the case in GSP was the opposite. The combustion rate of the residual carbon in GE slag was the fastest, mainly due to its large specific surface area, more amorphous carbon structure and active site, and the comprehensive combustion index of residual carbon in GE slag was 5.26×10−7 %2/(min2·oC 3).
Abstract: The catalytic behaviors of Ca-modified HZSM-5 during oil shale pyrolysis process were investigated in a tubular rector and by TG-MS-FTIR. The physicochemical properties of the molecular sieve were characterized by BET, NH3-TPD, and TG. The results show that the molecular sieve can significantly increase yields of C1−4 aliphatic hydrocarbons and reduce their evolution temperatures. After modified, Ca/HZSM-5 can reduce yields of CO2, increase yields of shale oil and decrease lengths of aliphatic chains in shale oil. But Ca/HZSM-5 has a strong catalytic effect on aromatization. Brönsted acid sites have an obvious catalytic effect on aliphatic hydrocarbons, while Lewis acid sites are more targeted at aromatization process of pyrolysis products.
Abstract: The catalytic activity of an industrial waste alkali liquor for coal gasification was identified, and the WJT coal impregnated of black liquor (BL) was gasified with steam under the temperatures 700−750 ℃ at high pressure. The effects of major process variables such as catalyst loading and temperature were investigated, which was also in comparison with Na2CO3 (SC). The results show that with an increase in the catalyst loading the gasification rate and the carbon conversion rise first and then drop, having the highest values at a 3% of Na loading and being higher than that with SC. Meanwhile, the catalytic activity increases with increasing the gasification temperature. The influence of BL addition on the BET surface area and pore volume was studied by an isothermal N2 adsorption-desorption experiment. It is indicated that the BET surface area and pore volume increase at first and then decrease with an increase in the BL loading. The increase of surface area and pore volume provide more gasification active sites and thus promote the reactivity of char gasification. However, the blocking of pores in coal char caused by excess catalyst loading can result in a decrease in the surface area and pore volume and thus the declining of the gasification rate.
Abstract: Group composition distribution of raw coal tar pitch is the key factor to determine quality of needle coke. The components of coal tar pitch were separated by ultrasonic solvent extraction. Effect of each group composition on mesophase characteristics was investigated. The group components were well blended to explore impact of different components on formation and development of mesophase structure. The results show that n-hexane soluble fraction (HS) is rich of aliphatic functional groups, and the excessive amount of HS fraction is not conducive in formation of large scale mesophase. Nevertheless, an appropriate amount of HS can maintain a proper lower viscosity in a long time range of the melting pitch system, which is significantly beneficial to growth and development of mesophase. Toluene insoluble substance (TI) is mainly consisted of dense cyclic aromatic hydrocarbon with high degree of polymerization. It can accelerate generation and development of mesophase sphere. However, excessive TI fraction can lead to generation of mosaic structure and reduce quality of needle coke. The green coke obtained from n-hexane insoluble and toluene soluble matters (HI-TS) demonstrate better optical anisotropy structure and is considered be the most suitable component for preparation of needle coke. The refined pitch with HS≈25%, HI-TS≈69%, and TI≈3%−8% can produce needle coke with well-developed mesophase structure and low thermal expansion coefficient.
Abstract: A Co/Al2O3 catalyst was synthesized by facile calcination and hydrogen reduction of a cobalt-aluminum hydrotalcite CoAl-LDH, and the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photon spectroscopy (XPS) were used to characterize the physical and chemical properties of the precursor and catalysts. Using 2-naphthyl ether as the lignite derived model compound, the catalytic performance of Co/Al2O3 on the hydrodeoxygenation of 2-naphthyl ether to monomeric hydrocarbons was investigated. The results show that Co/Al2O3-700 has the highest hydrodeoxygenation activity. Under the conditions of 250 ℃, 2 MPa of initial H2 pressure and90 min of holding time, the 2-naphthyl ether is completely converted to monomeric hydrocarbons (decalin and tetralin), in which the 2-naphthyl ether is first converted to 6,6'-oxybis (1,2,3,4-tetrahydronaphthalene) by hydrogenation and then the tetralin and 5,6,7,8-tetrahydronaphthalene-2-naphthol are formed by the cleavage of C−O bond. In addition, Co/Al2O3-700 also shows high activity for the hydrodeoxygenation of lignite-derived benzyl ether and phenyl ether model compounds.
Abstract: In order to realize high value utilization of wood vinegar, a series of Ni based catalysts with different Co contents prepared by impregnation method were tested in a fixed bed reactor. The effects of liquid space-time velocity, reaction temperature and Ni/Co ratio on hydrogen production, carbon conversion, H2 selectivity and carbon deposition were investigated. The catalysts were characterized by XRF, H2-TPR, SEM and elemental analysis. The results show that the gas production increases with the increase of space-time velocity of liquid, but the catalyst deactivation is accelerated when the space-time velocity of liquid is too high. High temperature is conducive to the catalytic reforming of wood vinegar to produce hydrogen. When the temperature reaches 900 °C, the hydrogen yield is the highest. With the increase of cobalt content, the carbon deposition and hydrogen yield decrease. Therefore, when the liquid space velocity is 60 h−1 and the temperature is 800 °C, the Ni-0.5Co/Al2O3 catalyst is most conducive to the hydrogen production experiment of wood vinegar.
Abstract: Ru-Co3O4 catalyst was prepared by the co-precipitation method. Its catalytic performance in liquid-phase hydrogenation of CO2 into methane was investigated, and compared with those of the conventional Ru-based catalysts (Ru/SiO2, Ru/CeO2, Ru/ZrO2, Ru/TiO2) prepared by impregnation method. The solvents including H2O, n-butanol, 1,4-butyrolactone, DMF, n-nonane, decalin, cyclohexane and isooctane had significant solvent effects on the catalytic performance. Compared with other solvents, the catalyst showed higher activity and selectivity catalytic performance when decalin and isooctane was applied as the solvent. At 200 °C and H2/CO2=3:1 (v/v, 4 MPa) and with decalin as the solvent, the conversion of CO2 and the selectivity of CH4 reached 45.6% and 97%, respectively. The isotope labeling experiments and in-situ diffuse reflectance infrared spectra showed that the hydrogen atoms of the tertiary carbon in decalin and isooctane were active for CO2 hydrogenation reaction, thus improving the catalytic activity.
Abstract: The carbon deposition and sintering of Ni-based catalysts, used in CO methanation, are the main problems to be solved. In this paper, supported LaNiO3/Al2O3-ZrO2 catalyst was prepared by neutralization hydrolysis-citric acid complexation method. The effects of La-Ni loading and calcination temperature of support on the structure and catalytic activity of the catalyst were investigated. The structural evolution of catalyst precursor before and after reduction was studied via XRD, H2-TPR, BET, XPS, TEM and other characterization methods. The results showed that the catalyst supported by homogeneous Al-Zr solid solution was beneficial to form the active component with LaNiO3 structure, and the Ni0 derived from LaNiO3 was the key factor for keeping the activity at high temperature. The La-Ni loading affected the formation of LaNiO3 and the reduction state of Ni. Among the catalysts studied, 30% of the La-Ni loading was more favorable for the formation of perovskite LaNiO3. The Ni0 and La2O3 reduced from LaNiO3 were highly dispersed on the surface of the support, and the Ni0 nanoparticles were anchored by the support and La2O3, which inhibited the migration and aggregation of Ni0 particles at high temperature and thus led to high thermal stability.
Abstract: The preparation of efficient catalysts in hydrogen evolution reaction (HER) is an urgent task at present. In this work, Ni(OH)2/Ni/g-C3N4 composite catalyst was prepared through liquid phase impregnation with in-situ reduction, which was used to compose the cathode with carbon paper (CP) for the microbial electrolysis cell (MEC). With the help of SEM, TEM, XRD, XPS and electrochemical analysis techniques, the structure, properties and electrocatalytic performance in hydrogen evolution of the Ni(OH)2/Ni/g-C3N4 composite were investigated. The results indicate that the Ni(OH)2/Ni/g-C3N4 catalyst exhibits excellent electrochemical activity for hydrogen evolution in the MEC. Using the Ni(OH)2/Ni/g-C3N4 catalyst, the current density reaches 100 A/cm2 at a small overpotential of 1881 mV, with a low charge transfer resistance of 10.86 Ω and a low Tafel slope of 44.3 mV/dec, which is much superior to pure g-C3N4 catalyst and CP, and even comparable to the Pt catalyst, suggesting that the Ni(OH)2/Ni/g-C3N4 composite can be a potential candidate of HER catalyst in MEC.
Abstract: A series of supported CuO/La1−xCexCrO3 catalysts were prepared by the sol-gel method and the effect of Ce doping in the A site on their structure, properties and catalytic performance in the steam reforming of methanol were investigated. The results indicate that the Ce doping impacts mainly on the reduction performance of CuO and the interaction between the perovskite support and CuO, which in turn influences the catalytic performance of CuO/La1−xCexCrO3 in methanol steam reforming. In particular, the CuO/La0.8Ce0.2CrO3 catalyst demonstrates adequate performance in methanol steam reforming; over it, the methanol conversion reaches 100% under 280 °C, water/methanol molar ratio of 1.2 and methanol gas hourly space velocity of 800 h−1.
Abstract: CeO2 aerogel (CeO2-A), nanorod (CeO2-R) and nanoflake (CeO2-F) were prepared via sol-gel, hydrothermal and coprecipitation methods, respectively. The effect of morphology and structure of CeO2 on the catalytic performance in toluene combustion reaction was investigated based on structure analysis provided by characterization. The results revealed that the activity of both CeO2-R and CeO2-F was inferior to that of CeO2-A, due to CeO2-R and CeO2-F smaller specific surface area only exposed (111) crystal plane dominantly detected from their TEM images. While, the CeO2-A had a larger specific surface area and more exposed (111) and (100) facet, which contributed to exposure and formation of more oxygen vacancies and further to the adsorption of more gaseous oxygen. In addition, highly mobile lattice oxygen was another critical factor for influencing the catalytic performance of CeO2, which was beneficial to the redox cycle of Ce3+/Ce4+ and could further accelerate the toluene combustion. As a result, the CeO2-A catalyst exhibited the superior performance in toluene catalytic combustion with t50 of 223℃ and t90 of 239℃, respectively, owing to the larger specific surface area, higher exposure of reactive crystal plane and stronger mobility of lattice oxygen.
Abstract: The UiO-66 catalysts with different doping ratio of Fe were prepared by hydrothermal synthesis method in this study. The physicochemical properties of the catalysts were characterized by means of XRD, SEM and XPS. The benzene removal efficiency of the catalysts was investigated using a bench-scaled heterogeneous Fenton-like system device. The effects of Fe loading amount, H2O2 concentration, superficial velocity and reaction temperature on benzene removal efficiency were studied. The results showed that the Fe doped UiO-66 was irregularly spherical and of high crystallinity. The highest benzene removal efficiency was obtained at 93% over the catalyst with 30% Fe loading. The EPR results proved that increasing Fe loading on UiO-66 evidently promoted the production of ·OH radicals, which promoted the degradation of benzene to a certain extent. The benzene removal efficiency decreased with the rise of temperature at higher range because H2O2 was unstable at high temperature.
Abstract: In this paper, RuO2/ZrO2 catalyst and WO3 doped RuO2/WO3-ZrO2 catalysts with different WO3 loadings were designed and prepared for selective catalytic oxidation of ammonia. Among the catalysts, RuO2/ZrO2 catalyst exhibits excellent catalytic activity but poor N2 selectivity. It is worth noting that the activity of RuO2/ZrO2 catalyst remains unchanged after 5% or 10% WO3 doping, while the N2 selectivity at high temperature is significantly improved, and NH3 is completely transformed at 225 ℃. However, when WO3 content rises to 15% and 20%, the catalytic activity of RuO2/ZrO2 catalyst decreases slightly, while N2 selectivity is not further improved at high temperature. Therefore, it can be judged that the optimal WO3 content is 10%. In addition, it is found that WO3 doping can change the microstructure of the catalyst and the corresponding specific surface area increases with the increase of WO3 content through BET analysis. XRD, H2-TPR and XPS show that WO3 doping can change the crystal structure of ZrO2, increase the stability of the catalyst. According to the DRIFT spectra results, as WO3 is doped into the catalyst, the amount of surface acid sites on the catalyst increase. More surface acid sites can facilitate the adsorption of ammonia species, inhibit the rapid reaction between ammonia and oxygen, and avoid formation of more by-products, which are the key factors to improve the N2 selectivity.
Abstract: Mullite-based ceramsite was prepared from coal gangue and bauxite. With ceramsite, ferric nitrite and glucose as raw materials, Fe/C/Mullite-based ceramics composite material was prepared by wet chemical synthesis technology combined with calcination at 900 ℃ in argon atmosphere. In the composite materials, C with a certain degree of graphitization covered the surface of the ceramsite, and Fe particles were uniformly dispersed in the grid of C layer. Due to the dielectric loss caused by the conductive polarization derived from the Fe particles and graphite, as well as the interfacial polarization derived from the interface between loading substance and matrix, the material showed enhanced absorption performance. When the ferric nitrite concentration in the initial solution was 0.1 mol/L, the sample FeCM-0.1 exhibited the best absorbing properties. The minimum reflection loss value of −13.9 dB was obtained at 14.6 GHz with a matching thickness of only 2.0 mm and the corresponding effective bandwidth was 3.6 GHz. This study provides a new way for the production of low-cost microwave absorbing materials and the resource utilization of solid waste coal gangue.
Abstract: At present, non-thermal plasma technology has received extensive attention in the treatment of solid waste. Based on the density functional theory (DFT), the conversion path of leucine (LEU) as the model compound of protein in sludge during the non-thermal plasma treatment was simulated at the B3LYP/6-31G(d,p) level; 7 main conversion paths were considered, including the deamination priority mechanisms, decarboxylation priority mechanisms, and the remaining C−C bond breaking priority mechanisms. The results show that leucine is easy to lose the amino group and carboxyl group, generating C5H10 which is further decomposed into small molecular hydrocarbons. The CO2 product comes from the carboxyl group; although the reaction barrier to form CO is relatively high, CO2 is easily ionized into CO in the plasma, leading to the increase of CO concentration. The combination of small free radicals and the decomposition of other small molecules generate CH4 and H2. The energy required for all paths is within the maximum value of the high-energy electron energy in the non-thermal plasma.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
