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2021, 49(2): 1-8.  
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Structural features and combustion reactivity of residual carbon in fine slag from entrained-flow gasification
LÜ Deng-pan, BAI Yong-hui, WANG Jiao-fei, SONG Xu-dong, SU Wei-guang, YU Guang-suo, ZHU he, TANG Guang-jun
2021, 49(2): 129-136.   doi: 10.1016/S1872-5813(21)60011-7
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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).
Effect of Ca modified HZSM-5 zeolites on catalytic pyrolysis of oil shale
YANG Tian-hua, LIU Jia-xing, LI Bing-shuo, ZHAI Ying-mei, WANG Jian, TONG Bo-lin
2021, 49(2): 137-144.   doi: 10.19906/j.cnki.JFCT.2021033
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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.
Catalytic effects of industrial waste alkali liquor in pressurized steam gasification of coal char
WANG Hui-fang, LI Peng, ZU Jing-ru, LI Ke-zhong
2021, 49(2): 145-150.   doi: 10.19906/j.cnki.JFCT.2021010
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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.
Influence of group component distribution of coal tar pitch on mesophase structure development of needle coke
LIN Xiong-chao, SHENG Zhe, SHAO Ke-ke, XU De-ping, WANG Yong-gang
2021, 49(2): 151-159.   doi: 10.19906/j.cnki.JFCT.2021008
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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.
Catalytic hydrodeoxygenation of lignite-derived model compounds to monomeric hydrocarbons over Co/Al2O3
ZHAO Yun-peng, SI Xing-gang, ZHAO Wei, CAO Jing-pei, WEI Xian-yong
2021, 49(2): 160-167.   doi: 10.19906/j.cnki.JFCT.2021032
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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 and 90 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.
Hydrogen production from wood vinegar reforming over cobalt modified nickel-based catalyst
LIANG Chang-ming, ZAHNG An-dong, LI Zhi-he, LI Yu-feng, WANG Shao-qing, YI Wei-ming
2021, 49(2): 168-177.   doi: 10.19906/j.cnki.JFCT.2021016
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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.
Solvent effect on the activity of Ru-Co3O4 catalyst for liquid-phase hydrogenation of CO2 into methane
SONG Ying-jian, CUI Xiao-jing, DENG Tian-sheng, QIN Zhang-feng, FAN Wei-bin
2021, 49(2): 178-185.   doi: 10.1016/S1872-5813(21)60013-0
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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.
Formation of perovskite-type LaNiO3 on La-Ni/Al2O3-ZrO2 catalysts and their performance for CO methanation
WANG Hong-wei, WU Jun-xia, WANG Xiao-yan, WANG Hong, LIU Jin-rong
2021, 49(2): 186-197.   doi: 10.1016/S1872-5813(21)60012-9
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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.
Ni(OH)2/Ni/g-C3N4 composite: An efficient electrocatalyst for hydrogen evolution
ZHANG Jie, ZHAO Yu, WU Ai-lian, LI Jia, WANG Yu-xue
2021, 49(2): 198-204.   doi: 10.1016/S1872-5813(21)60010-5
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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.
Preparation of core-shell catalysts for one-step synthesis of dimethyl ether from syngas
WANG Wen-li, WANG Yan, CHEN Yue-xian, ZHAO Wen-chao, LI Rui-feng
2013, 41(08): 1003-1009.  
[Abstract](1958) [PDF 0KB](0)
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A core-shell catalyst CuO-ZnO-Al2O3@Al2O3 for one-step synthesis of dimethyl ether from synthesis gas was prepared using glucose, sucrose or starch as template, and characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The thickness of the Al2O3 shell in the catalyst was altered by controlling the synthesis condition, such as temperature and time. The catalytic performance of dimethyl ether (DME) synthesized from CO hydrogenation on the catalysts were investigated. The conversion of CO and the selectivity of DME on CuO-ZnO-Al2O3@Al2O3 achieved 35.2% and 61.1% at 260 ℃, 5.0 MPa and 1 500 mL/(h·gcat), respectively.
Effect of wastewater treatment processes on thermal treatment properties of sewage sludge
JIE Li-Beng, Zheng-Shi-Mei, LI Chao
2009, 37(04): 501-505.  
[Abstract](1443) [PDF 0KB](0)
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The properties of pyrolysis and combustion for five different sewage sludges are studied by thermal gravimetric analysis at a heating rate of 10℃/min in the atomosphere of nitrogen and oxygen, respectively. The results show that both of the “anaerobic” wastewater treatment and the sludge anaerobic digestion make the organic compounds in sludge so complicated that the organic compounds decomposition and release temperature becomes higher during pyrolyzing, and the “aerobic + anaerobic” process makes the organic compounds in sludge more complicated than the “anaerobic +aerobic” process. There is no influence on the combustion process and the burnout point, but can make the combustion temperature of sludge higher. The thermal reaction mechanisms have been studied with šatava-šesták equation. It shows that the pyrolysis mechanism of these sludges is a process of volatile diffusion at first and then the chemical reaction function, while the combustion mechanism of them is a process of chemical reaction and diffusion function.