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Abstract(34) HTML(41) PDF 1274KB(5)
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The three-component coupling of methanol, CO2 and propargyl alcohol to manufacture dimethyl carbonate (DMC) provides a new, thermodynamic favorable and green chemical synthesis route. In this work, to overcome the problems of low DMC yield and slow conversion rate of intermediates, the synergistic catalytic strategy of silver sulfadiazine and superbase is developed to improve the reaction efficiency. The effect of various parameters i.e. catalyst and cocatalyst types, catalyst loading, solvent, temperature, proportion of raw materials, pressure and time on the coupling reactions is investigated in detail. Under the optimal conditions, the selectivity of DMC is 89.5% with the yield of 55.6%. And the effect of alkyne derivative α-monosubstituted propargyl alcohol on the efficiency and selectivity of DMC are also studied. The mechanism study shows that propargyl alcohols with different structures apparently affect the reaction process, and the synergistic catalysis of silver sulfadiazine/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is the reason for the high yield and selectivity of DMC.
Abstract(34) HTML(13) PDF 15654KB(4)
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The isothermal steam gasification experiments of a ternary mixture (BTP) containing black liquor char (BLC), causticizing agent (TiO2), and petroleum coke (PC) were carried out at 850 °C based on a thermogravimetric analyzer (TGA) and a horizontal fixed-bed reactor. A co-gasification process of BLC and PC coupled with TiO2 direct causticization was explored from the aspect of reaction rate as well as the characteristics of gaseous products and gasification residues (GR). The results show that in comparison to the weighted average (BTPtheo) of the independent gasification of TiO2 direct causticized BLC and PC, significant synergistic effects could be aroused during the coupled co-gasification process due to promoting action of mNa2nTiO2 on gasification of organic carbon. Specifically, the maximum reaction rate of BTP reaches 7.0%/min, which is 2.9 times that of BTPtheo. The content and yield of effective gas components, i.e., H2+CO, in the gas products, as well as its lower heating value (LHV) of BTP are 81.1%, 2059 mL/g, and 9343 kJ/m3, respectively, which is 6.8%, 137.3%, and 5.5% higher than that of BTPtheo. The carbon conversion and energy output ratio of BTP reaches 95.0% and 1.13, respectively, which is increased by 61.6% and 135.4% relative to the theoretical superposition value. In addition, the relative loss of inorganic salts in BTP during the whole thermochemical conversion process is effectively controlled at a lower level of about 9.4%. Since the Na-containing salts in GR of BTP are mainly mNa2nTiO2 with higher thermal stability, and GR maintains good particle flowability, it is conducive to downstream alkali recovery.
Abstract(22) HTML(10) PDF 6209KB(1)
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In order to realize the effective resource utilization of coal gasification residues (CGR), the composite microwave absorbents loaded with different magnetic components were prepared through wet chemical impregnation and roasting progress, recycling of coal gasification residue as carbon-based carrier. The results showed that the main reaction involved in gradual carbothermal reduction reaction, during which the Fe2O3 and Fe3O4 were transformed into Fe. And part of high-activity carbon in CGR was consumed as well, which resulted in the poor graphitization degree of CGR composites. Benefitted from the better impedance matching and attenuation characteristic, FeCGR1000 displayed excellent microwave absorbing performance. The reflection loss value reached −25.3 dB under the coating thickness of 2.0 mm, and the effective bandwidth kept 4.0 GHz as the coating thickness remained 1.5 mm. This work not only benefitted for realizing the resource utilization of CGR, but also provided new ideas for the high additional value application for CGR.
Abstract(22) HTML(16) PDF 1755KB(5)
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Alkaline earth metal calcium is a typical poison in coal-fired power plants, which will result in deactivation of SCR catalyst. The ATMP (amino trimethylene phosphonic acid) and PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid) complexing agents were employed for the regeneration of a poisoned by calcium V2O5-WO3/TiO2 catalyst. The physical and chemical properties and regeneration denitration performance of the catalyst before and after regeneration were investigated by BET, NH3-TPD, H2-TPR, XPS and experiments. The results indicated that the ATMP and PBTCA exhibited efficient regeneration performance, and the NOx conversion of regenerating catalysts recovered from 25.8% to 89.8% and 88.1% at 400 ℃, respectively. Compared with the regeneration by dilute sulfuric acid, the ATMP and PBTCA exhibited a higher calcium removal rate with lower vanadium loss (less than 5%). The utilization of the ATMP and PBTCA can effectively restore the Brønsted acid sites, active vanadium V5 + and the surface chemisorbed oxygen Oα on the catalyst surface, which leads to the overall activity of the catalyst reaching an optimal level. Therefore, it has a great potential to apply ATMP and PBTCA complexing agents in the regeneration of deactivated SCR denitration catalysts.
Abstract(11) HTML(7) PDF 1928KB(1)
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Solid oxide fuel cell (SOFC) is a promising power-generation device. Direct operation of SOFC on methane has several important advantages, such as simple system, high efficiency and low emissions. The challenge of the state-of-the-art nickel cermet anode is prone to coke formation when operating on methane, which may cause rapidly deteriorate of the performance and durability on SOFC. In this work, the anode Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) was investigated for wet methane (97% CH4-3% H2O) conversion in the temperature range of 700 to 600 ℃. The Ni-BZCYYb anode showed a good electrochemical performance for the steam reforming of methane. Furthermore, under a constant current density, a good operational stability was achieved at 600 ℃ for 100 h operating. For comparison, a conventional Ni-YSZ anode was also prepared, the voltage of cell dropped to zero after feeding wet CH4 for ~ 6 h. These results indicate that the Ni-BCZYYb is a good candidate as the anode in SOFC on methane fuel.
Abstract(17) HTML(2) PDF 10933KB(3)
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The fusibility and viscosity-temperature characteristics of municipal solid waste (MSW) ash slag are important to the optimize design and operation of fixed bed slag gasifier. In this paper, the ash composition characteristics of these two MSW samples were analyzed, and the melting mechanism of MSW ash was explored by high temperature heating stage microscope (HTSM), X-ray diffraction (XRD) and FactSage. At the same time, the effect of crystal mineral formation on ash viscosity was analyzed by high-temperature viscometer, SEM-EDS and XRD. The results showed that the silica to aluminum ratio of MSW ash are both high, but the contents of aluminum and calcium are different. The flow temperature of YZ ash is about 150 ℃ higher than that of LG ash. Low temperature eutectic of wollastonite is the reason for the lower melting point of LG ash, and the existence of quartz and spinel at high temperature leads to a higher melting point of YZ ash. Ash melting behavior of LG and YZ are both "melt-dissolution" mechanism, and they both undergo shrinkage, melting and diffusion processes with the increase of temperature. The viscosity- temperature curves of LG and YZ are both glassy slag. However, the viscosity-temperature characteristics of YZ ash are relatively poor, which is related to the formation of anorthite during the cooling process. So the application of YZ requires a high slag discharge temperature. LG ash has good fusibility characteristics and viscosity-temperature characteristics, so the gasifier with this material can operate in a wide temperature range.
Abstract(23) HTML(8) PDF 1138KB(6)
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In this work, a series of nano LaCoO3 perovskite catalysts were effectively synthesized by a sol-gel method through modulating the La/Co molar ratio. These catalysts were characterized by ICP, XRD, N2 sorption, H2-TPR, O2-TPD, and XPS, and their catalytic performance in the lean methane combustion were then investigated. The results indicate that highly dispersed Co3O4 nanoparticles on the LaCoO3 perovskite catalysts are beneficial to the activation of CH4 at a low temperature, while the La-Co-perovskite bulk phase can provide a large amount of lattice oxygen, which can enhance the reaction rate of methane combustion and the catalytic stability at a high temperature. Through altering the La/Co molar ratio, the dispersion of Co3O4 nanoparticles in the La-Co-perovskite catalyst can be effectively modulated, to achieve the concurrence of low-temperature activity and high-temperature stability in the lean methane combustion. In particular, the La0.9CoO3 perovskite catalyst with a La/Co molar ratio of 0.9 exhibits excellent performance in lean methane combustion, with a light-off temperature of 382 ℃ at a space velocity of 30000 mL/(gcat·h), the light-off temperature of methane is 382 ℃, and the methane conversion rate is still maintained above 95% after 72 h of stable operation, indicating that the highly dispersed Co3O4 nanoparticles were beneficial to the low-temperature activation of CH4, and the lanthanum-cobalt-perovskite bulk phase in the catalyst could provide a large amount of lattice oxygen, which promotes the catalytic combustion rate of CH4 and the high-temperature stability of the catalyst under high-temperature conditions. By modulating the lanthanum-cobalt ratio, the dispersion state of Co3O4 nanoparticles in the catalyst can be effectively modulated, and then the effective unification of low-temperature activity and high-temperature stability of the catalyst can be achieved, which guides the future development of low-cost, high-activity and high-stability catalysts for methane catalytic combustion.
Abstract(9) HTML(3) PDF 1299KB(2)
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With dolomite as the main aggregate, a clay ceramic carrier was prepared by one-step powder sintering method. After being impregnated with Ce and calcined, a Ce loaded dolomite based (Ce-Dol) clay ceramic catalyst was prepared, which was used for the catalytic gasification of pine wood. The influence of the addition amount of Ce, steam flow rate, gasification temperature and other parameters on the catalytic gasification of pine wood was investigated using a self-developed two-stage gasifier, and the optimal operating conditions were determined. The results show that the dolomite based clay ceramics loaded with cerium can effectively improve the catalytic activity, reduce the stretching vibration peak absorbance of some functional groups in the gasification products, effectively promote the secondary cracking of tar, and improve the quality of gaseous product. When catalyzed by the Ce-Dol clay ceramic containing 6% cerium, the volume fraction of H2 peaks with 32.43%. With the rise in gasification temperature, aliphatic carboxylic acids and ketones in biomass tar are gradually decomposed into small molecular compounds such as CO, CO2. The content of H2 shows an ascending trend, and a maximum value is reached at 900℃. Moreover, adding an appropriate amount of steam promotes the forward water-gas reaction, and a maximum volume fraction of H2 (37.37%) is achieved at a steam flow rate of 4 mL/min.
Abstract(33) HTML(10) PDF 1575KB(11)
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Elemental distribution, compositional variation, microstructural feature, surface pore structure, pyrolysis characteristic and reactivity of samples derived from inert/oxidative torrefaction performed in 493–573 K were investigated. The results illustrated that reaction temperature was the dominant factor affecting fuel quality of torrefied sample, and the addition of oxidizing agents would strengthen the variations in fuel properties after undergoing torrefaction. Increasing reaction temperature would promote the decomposition of oxygen containing functional groups from the particles, when torrefaction performed in raw flue gas atmosphere at 573 K, the H/C and O/C reached the minimum values (0.188 and 0.259). Additional oxidizing agents would synergistically modify the surface functionality distribution, microstructure and surface physical structure of rice husk particles, and the increase of temperature was beneficial to this phenomenon. The critical values were obtained from the sample torrefied in raw flue gas atmosphere at 573 K, the minimum I(Gr + VL + Vr)/ID value was 1.79 and the maximum specific surface area was 295.78 m2/g. By means of the utilization of Coats-Redfern approximation function, the pyrolysis kinetics (14.84 → 28.82 kJ/mol) and characteristic parameters would be determined via the TGA data for each sample. Flue gas seemed to be more energy-saving and efficient for improving fuel quality and storage stability of biomass.
Abstract(249) HTML(46) PDF 1599KB(69)
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The development of novel carbon dioxide capture or utilization technology is of great significance to reduce carbon dioxide emissions from fossil energy utilization, as well as to alleviate global warming. The integrated carbon dioxide capture and utilization (ICCU) technology, which integrate carbon dioxide adsorption and in-situ conversion to realize efficient conversion of carbon dioxide to carbon containing fuels over dual function material, has attracted extensive attentions due to its advantages of low energy consumption and high efficiency. In this paper, the composition and characteristics of the dual function materials for CO2 capture and methanation were summarized. The factors which affected the methanation process were discussed from the perspectives of reaction temperature, reaction time, feed gas compositions. The challenges and opportunities in the near future were also proposed.
Abstract(84) HTML(31) PDF 31586KB(32)
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Dry reforming of methane (DRM) technology, converting two kinds of greenhouse gases (CH4 and CO2) into syngas to achieve greenhouse gas emission reduction and resource utilization, has attracted more and more attention from researchers. Due to the advantages of high specific surface area, developed porous structure, high thermal stability, excellent acid and alkali resistance, abundant content of alkali/alkaline earth metals and oxygen-containing functional groups, and low cost, bio-char is suitable for different DRM systems, including shale gas, oil field associated gas, coke oven gas and coal bed methane systems, which can avoid some pretreatment processes such as desulfurization of part of the exhaust. Therefore, bio-char may offer attractive prospects for large-scale DRM industrial applications. Herein, the review briefly summarizes the preparation process of biochar-based catalyst supports for DRM. The different carbonization procedures and their effects on the yield and properties of bio-char are briefly described. The advantages and influence factors of the physicochemical property of bio-char in the reforming reaction are introduced. The influence of different activation methods on the catalytic performance of biochar-based catalysts is also analyzed. Finally, the carbon consumption that affects the stability of the catalyst is briefly introduced.
Abstract(29) HTML(12) PDF 1147KB(5)
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Ash content is an important factor affecting the quality and combustion performance of biochar. In this paper, a method of ash removal by carbonization followed by CO2-enhanced water washing is proposed. The effects of carbonization temperature of bagasse biochar, temperature and time of CO2-enhanced water leaching on deashing were investigated. The results showed that the deashing rate first increased and then decreased with the increase of carbonization temperature, while the trend was opposite with the increase of deashing temperature and time. For bagasse biochar pyrolyzed at 300 ℃, the deashing rate reached 57% at the water leaching temperature of 40 ℃ for 4 h. Compared with water leaching before carbonization, carbonization followed by deashing increased the content of fixed carbon and the carbon yield by 7% and 3%, respectively. It is analyzed that, in the process of deashing, CO2 diffuses and dissolves into water to form carbonic acid, and reacts with part of metal salts to form water-soluble salts, resulting in removal rate of K, Na and Ca up to above 50%, and part removal of calcite and dolomite. Compared with water leaching alone, the proposed process shows higher deashing rate and universality, but the deashing rate is related to the ash compositions and kinds of biochar. The deashing rate of peanut shell and poplar pyrolytic charcoal exceeds 30%.
Abstract(62) HTML(13) PDF 1219KB(14)
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In order to improve the efficiency of biomass gasification to hydrogen production, the comprehensive utilization of industrial solid waste resources, the use of calcium-based waste - calcium carbide slag as a CO2 adsorbent, in a two-stage fixed bed to explore the effect of calcium-based waste addition, reaction temperature on the biomass gasification hydrogen production characteristics, focusing on the study of the adsorbent in practical applications of the cyclic adsorption performance, and thus discuss the influence mechanism of calcium carbide slag on biomass adsorption enhanced gasification. The results show that with the gradual increase of calcium carbide slag addition, H2 yield and concentration show an increasing trend. With the increase of temperature, the yield and concentration of H2 increase first and then decrease. When the CaO/C molar ratio is 1 and the temperature of the reforming section is 700 ℃, the yield and concentration of H2 in the gas product are 154.34 mL/g biomass and 26.76%, and the maximum value is obtained. When the number of calcium carbide slag cycles is less than 5, the concentration and yield of H2 increase compared to the initial reaction.
Abstract(16) HTML(3) PDF 1523KB(3)
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The cathode material La1.5Sr0.5Ni1−xCoxO4 + δ (x=0, 0.2, 0.4, 0.6) of Co doping La1.5Sr0.5NiO4 + δ (x = 0, 0.2, 0.4, 0.6) is synthesized using a sol gel method. Through the measurement of X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric, the thermal expansion coefficient, the scanning electron microscope tests the phase structure, elements, thermodynamic properties, and surface morphology of the material. The result shows, all samples successfully synthesized a single pure phase with perovskite-like structure, the doping of Co elements has increased the thermal expansion coefficient of the material. In order to explore the material to be used in the feasibility of the SOFC cathode, the measurement of electrical conductivity and electrochemical impedance spectroscopy was carried out. Conductivity increases with the increase of Co element doping, at 800 ℃, La1.5Sr0.5Ni0.6Co0.4O4 + δ conductivity is the highest, with 51.21 S/cm, when the value of Co is greater than 0.4, the conductivity is significantly reduced. The material also exhibits the lowest polarization resistance in electrochemical impedance spectrum test, at 700 ℃ value of 4.180 Ω·cm2, exhibits better electrochemical properties.
Abstract(76) HTML(21) PDF 6461KB(13)
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In this study, we used density functional theory to study the adsorption and activation capacity of Cu13, Cu12Zn, and Cu12Zr clusters for CO2 reduction. The calculated results showed that Cu12Zr enhanced the adsorption capacity of reactants and intermediates compared with Cu13 clusters, while Cu12Zn clusters decreased the adsorption capacity of reactants and intermediates. We calculated that the energy barriers for CO2 reduction to CO on Cu13, Cu12Zr, and Cu12Zn clusters are 0.65, 0.35 and 0.58 eV, respectively, and the energy barriers for CO2 plus H to generate HCOO are 0.87, 0.77 and 0.49 eV, while the energy barriers of CO2 hydrogenation to COOH are 1.67, 1.89 and 0.99 eV. The doping of Zn and Zr elements improved the CO2 catalytic reduction ability of the Cu clusters, which showed that the Cu12Zr clusters were favorable for the dissociation of CO2 to form CO, and the Cu12Zn clusters were favorable for the hydrogenation of CO2 to HCOO.
Abstract(23) HTML(8) PDF 5541KB(7)
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The complexity and diversity of lignin derived bio-oil (LDB) has posed a great challenge to the subsequent processing and utilization. In this work, HZSM-5 was modified by sodium hydroxide and followed by Ni, Cu and Ru species. LDB was used as the raw biocrude to prepare bio-oil rich in aromatic hydrocarbons with modified HZSM-5 catalysts under supercritical ethanol conditions (320 °C, 14 MPa). Results showed that the desilicated HZSM-5 with the loading of Ni, Cu and Ru (Ni-Cu-Ru/DeHZSM-5) exhibited the best catalytic performance with a high relative amount of aromatic hydrocarbons of 28.95%. After catalytic hydrodeoxygenation (HDO) of LDB, 80.40% upgraded bio-oil (UBO) with 96.32% energy recovery was obtained in the presence of Ni-Cu-Ru/DeHZSM-5. Demethoxylation and dehydration were the main reactions in the catalytic HDO process. Potential reaction pathways of guaiacol, syringol and creosol were also proposed in this paper. The heating value of UBO reached 35.22 MJ/kg compared with LDB, which was increased by 19.80%. The water content and viscosity of UBO were also significantly improved. The micro-mesoporous structure of modified HZSM-5 with loading of Ni, Cu and Ru was beneficial to promote the yield of the aromatic hydrocarbons.
Abstract(24) HTML(5) PDF 3949KB(9)
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Thermal degradation mechanism of polybutylene terephthalate (PBT) dimer was studied by density functional theory (DFT) method M06-2X/6-311G(d). Eight possible reaction paths were designed for the thermal decomposition of PBT dimer, and the thermodynamic and kinetic parameters of elementary reaction steps in each reaction path were calculated. Calculation results show that, in the initial pyrolysis process of PBT, the energy barrier of concerted reaction occurred on the main chain is significantly lower than that of the radical reaction, so the terephthalic acid, monobutene terephthalate, dibutene terephthalate and diterephthalic acid-1,4-butylene diester formed by concerted reaction are main products in PBT initial pyrolysis. The reaction energy barrier of the main chain fracture through the six-membered cyclic transition state is lower than that through the four-membered cyclic transition state, and the main chain fracture of PBT is mainly through the concerted reaction via six-membered cyclic transition state. In addition, the secondary degradation reaction of the main products of PBT pyrolysis was also discussed. It was found that the main products such as 1,3-butadiene, tetrahydrofuran, benzene, CO2 and benzoic acid were mainly generated through concerted reaction in the processes of secondary degradation reaction.
Abstract(58) HTML(23) PDF 806KB(10)
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Methyl N-phenylcarbamate (MPC) is an important intermediate for the synthesis of diphenylmethane diisocyanate (MDI), and its preparation using CO2 or its equivalents/derivatives as carbon source represents a green and sustainable manner for fine chemicals synthesis. This review will highlight the development of MPC synthetic methods from the viewpoint of chemical fixation of CO2. The contents mainly include the introduction of MPC synthesis through CO2 equivalents (urea or phenyl urea) alcoholysis, dimethyl carbonate (DMC) aminolysis, and the coupling of DMC and diphenyl urea. Further more, one-pot synthesis of carbamates/MPC from aliphatic amines/aniline, CO2 and alcohols is highlighted which represents one of the most promising schemes in direct CO2 utilization. What is more, the reaction mechanisms and selection of catalysts are also discussed in detail. The advances will provide important theories on further improving the efficiency of green catalysis and sustainable chemical processes.
Abstract(12) HTML(11) PDF 1315KB(1)
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A series of Cu(x)/Hβ catalysts were prepared by the impregnation method and the effect on the performance of the catalysts for the selective catalytic reduction of NO with NH3 (NH3-SCR) was investigated. Characterization techniques such as XRD, N2 adsorption-desorption, NH3 temperature programmed desorption (NH3-TPD), NO-TPD, H2 temperature programmed reduction (H2-TPR), energy dispersion X-ray spectrum (EDS) and X-ray photoelectron energy spectrum (XPS) were used to investigate the physical and chemical properties of the catalysts and the reason of the decrease of catalyst activity in the presence of SO2. It is shown that the catalyst (Cu(3)/Hβ), the Cu loading is 3 wt% and Cu(2)/Hβ, the Cu loading is 2 wt%, exhibited the better catalytic activity when the initial reaction material contains no SO2 and SO2, and T95 is 169 and 225 oC, respectively. The analysis results of the catalyst before and after the reaction showed that the main reason for the decrease of catalyst activity in the presence of SO2 is that the ammonium sulfur salt which is formed by the reaction of SO2 and NH3 in the low reaction temperature covers the catalyst active center.
Abstract(13) HTML(7) PDF 1901KB(4)
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Fe/C-based composite microwave absorption (MA) materials were prepared by high temperature solid phase reaction between coal hydrogasification semi-coke (SC for short) and solid waste red mud (RM). In order to optimize MA performance, initial system composition was changed. It was found that, under an argon atmosphere and reaction temperature of 900 ℃, the composites obtained from systems with mass ratio of SC to RM (MRSR) at 0.4∶1−0.7∶1 all showed excellent performance, and that corresponding to MRSR of 0.6∶1 was the best. At a coating thickness of 1.5 mm, the simulated minimum reflection loss and effective absorption bandwidth could reach −48.3 dB and 4.6 GHz, respectively. The strong intrinsic attenuation ability mainly resulted from the dielectric loss due to the presence of graphite carbon as well as a large number of phase boundaries and defects. And the impedance matching between material and free space was attributed to the effective regulation on electromagnetic parameters of the initial system composition. Moreover, the solid phase combination reaction among Na2O, Al2O3 and SiO2 could weaken the strong alkalinity caused by RM.
Abstract(55) HTML(37) PDF 6099KB(13)
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As one of the carbon reduction ways, chemical conversion of CO2 is continuously being concerned. The breakthroughs through thermal catalysis conversion have been carried out in recent years. However, there are still problems such as low ethanol selectivity and yield, and more by-products are produced. In this study, the progress in thermal catalysis of CO2 hydrogenation to ethanol was reviewed. The performance of catalysts with different supports of zeolites, metal oxides, perovskites, silicon dioxide, organic frameworks and carbon-based materials were mainly discussed. The influence of the synergistic effect between different metals on the CO2 conversion and the promotion effect of the intervention of various active species on the reaction were analyzed. The catalyst systems that can effectively promote the coupling of C–C bond, and have appropriate CO2 adsorption and activation performance were summarized. Based on above discussion, the conditions of CO2 hydrogenation to ethanol were summarized, and the reaction mechanism was discussed. The study is beneficial to design the catalysts, optimize the reaction conditions and understand the mechanism of CO2 hydrogenation to ethanol in the future.
Abstract(24) HTML(9) PDF 1511KB(2)
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Ce-Zr oxide support was hydrothermally synthesized from metal nitrates of cerium and zirconium as the raw materials using citric acid instead of alkali precipitant, and then Cu/Ce-Zr catalyst was prepared by the impregnation method. The support and catalyst samples were characterized by XRD, BET, H2-TPR, XPS techniques, and the effects of different hydrothermal time on the structure, properties and performance in water-gas shift reaction were investigated. The results show that the catalyst activity is mainly related to the Cu specific surface area, reduction temperature of CuO and the number of oxygen vacancies on the catalyst surface. Among them, the Cu/Ce-Zr catalyst with hydrothermal time of 12 h has a large Cu specific surface area, a lower reduction temperature of CuO, and a large number of oxygen vacancies, so it shows a good catalytic activity. When the reaction temperature is 320 ℃, the molar ratio of water to gas (W/M) is 2, and the gas space velocity GHSV=6600 h−1, the CO conversion rate is 96.9%, which is close to the thermodynamic equilibrium value of 97.1%.
Abstract(11) HTML(2) PDF 790KB(2)
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The effects of KCl-ZnCl2 molten salt on the pyrolysis characteristics and pyrolysis products of heavy bio-oil at 400 ℃, 500 ℃ and 600 ℃ were studied. The results showed that molten salt increased the solid yield of heavy bio-oil pyrolysis and decreased the gas yield. Some compounds such as phenol, cresol, ethylphenol and 4-propylphenol had good enrichment effect, especially the relative concentration of cresol increased from 8.82% to 20.85% at 400 ℃, while the relative concentration of phenol increased from 2.18% to 8.62% at 600 ℃. During the formation of char, molten salt reduced the content of carbon and increased the content of oxygen, increased the BET surface area and total pore volume of pores. Molten salt promoted the formation of solid products’ pore structure and increased the average pore diameter.
Abstract(19) HTML(10) PDF 4158KB(5)
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The Cu-M/ZnO catalysts (M = Zr4 + , Al3 + and Mg2 + ) for dimethyl oxalate (DMO) selective hydrogenation to ethylene glycol (EG) have been synthesized by the co-precipitation method. The texture properties of the as-synthesized catalysts were systematically characterized by the N2-physisorption, N2O-titration, XRD, H2-TPR, CO2-TPD, SEM, FT-IR and XPS focusing on the functions of the dopants. It is found that the incorporated dopants can significantly promote the Cu dispersion. Particularly, a trace of Mg2 + dopants can effectively strengthen the interaction between Cu and ZnO phases by embedding into the ZnO lattice, while the Cu/ZrO2 interaction could be reinforced with the Zr4 + dopant introduced. For DMO gas-phase hydrogenation, the EG yield of the Cu/ZnO catalyst increased from 75.0% to 85.0% and 90.0% in presence of Zr4 + and Al3 + dopants, respectively. Particularly, the EG selectivity of Cu-Mg/ZnO catalyst can reach up to 95.0% with DMO completely converted for more than 100 h. The correlation between the catalytic behavior and physicochemical features suggested that the Cu + sites should be vital for the catalytic behavior of the Cu/ZnO based catalysts with adequate Cu0 sites. Additionally, the strengthened Cu/oxide interaction favors the outstanding stability of the Cu-Zr/ZnO and Cu-Mg/ZnO catalyst in DMO hydrogenation.
Abstract(21) HTML(7) PDF 2984KB(4)
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As the most promising hydrogen storage material, hydrous hydrazine (N2H4·H2O) has attracted extensive attention and interest of researchers. In this paper, NiPt bimetallic supported SBA-15 (mesoporous silica) catalysts with different metal ratios were prepared by a simple impregnation reduction method, and their catalytic hydrous hydrazine dehydrogenation performance was studied. The research results show that Pt and Ni form an alloy during the preparation of the catalyst, the electronic synergistic effect of the two metals can effectively promote the catalytic performance of the catalyst, and the interaction between SBA-15 and the metal active components helps to improve the catalytic performance of the catalyst. Catalytic performance and cycling stability of catalysts. The activation energy of the Pt6Ni4/SBA-15 catalyst is 45.6 kJ/mol, TOF value is 2123.3 h−1, which are better than most of the reported catalysts.
Abstract(20) HTML(6) PDF 3840KB(2)
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Abstract(12) HTML(8) PDF 5125KB(3)
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La2O3 catalysts with different grain sizes were prepared under hydrothermal condition. The structure activity relationship of La2O3 catalysts with different grain sizes were investigated by using in-situ XRD, Raman, IR and H2-TPR,O2-TPD. The results show that the La-O bond of the La2O3 catalyst shows a significant elongation with increasing temperature, which affects its adsorption and dynamic storage of O2. When increasing the grain size up to 2.64 μm, the oxygen storage capacity of the La2O3 catalyst started to decrease, accompanied by the enrichment of surface oxygen species, especially superoxide species, on the catalyst surface, which led to the over-oxidation of CH4 and products and reduced the C2 + hydrocarbons selectivity. The L-La2O3 catalyst with a grain size of 0.488 μm has a suitable content of surface oxygen species and a high oxygen storage capacity at 750 ℃. It exhibited the best C2 + hydrocarbon selectivity up to a CH4/O2 of 3 and a vacancy rate of 160,000 ml·g−1·h−1.
Abstract(35) HTML(10) PDF 16782KB(5)
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In recent years, potassium ion batteries have become one of the important electrochemical energy storage devices in the new energy field because of their high energy, power density and excellent cycle stability. Among them, the physicochemical properties and structure of anode materials are the key factors affecting their electrochemical properties. In this paper, two-dimensional B/N co-doped porous carbon sheets (BNCSs) were prepared by one-step carbonization using glycine as carbon source and nitrogen source, boric acid as template and boron source. The boric acid template can be removed by water washing, and the synthesis method is green and environmentally friendly. The short pores in BNCSs shorten the transport distance of potassium ions, and the abundant micropores provide a large number of potassium storage active sites. In addition, the higher B/N doping in BNCSs increases the defect degree of carbon matrix, expands the carbon layer spacing, and is conducive to the adsorption, insertion and de-insertion of potassium ions. The measurement results of potassium ion half cell performance indicate that BNCS800 electrode shows high specific capacity (310 mAh/g at 0.05 A/g), excellent rate performance (100 mAh/g at 2 A/g) and good cycle stability (after 1000 cycles at 1 A/g, the capacity retention is 75.9%). This work provides a simple strategy for preparing cathode materials with high capacity and long life.
Abstract(7) HTML(4) PDF 1259KB(3)
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Single-atom Fe-modified nitrogen-doped carbon (Fe SA/N-C) is an effective alternative to Pt-based carbon for the cathode oxygen reduction reaction (ORR) of fuel cells. Herein, we anchored atomically dispersed Fe–N4 sites on hollow N-doped carbon spheres (Fe SAs/HNCSs-800) for electrocatalytic ORR; the obtained material exhibited electrocatalytic activity and stability comparable to that of commercial Pt/C, with an onset potential of 0.925 V and a half-wave potential of 0.867 V. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy results confirmed the presence of highly dispersed Fe single atoms in Fe SAs/HNCSs-800. The results of experiments and theoretical calculations show that the single-atom dispersed Fe-N4 serve as the ORR active sites, and the adjacent C defects can effectively regulate the electronic structure of Fe atoms and improve the electrocatalytic ORR activity.
Abstract(16) HTML(4) PDF 5912KB(0)
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The resources endowment characteristics of rich coal, lean oil and poor gas in China, synthesis of high value–added chemicals from coal–based raw materials can help reduce the dependence on foreign petroleum. Polyethylnaphthalenes lubricating base oil are synthesized by alkylation of cooking naphthalene with ethylene using organic ammonium salt/metal chloride ionic liquid as catalyst. It is found that the AlCl3/Et3NHCl ionic liquid showed better active in the naphthalene alkylation with ethylene by regulating the composition of anions and cations in ionic liquids. Two different compositions of polyethylnaphthalenes base oils PEN–1 (92.9% of mono– and di–ethylnaphthalenes) and PEN–2 (91.3% of polyethylnaphthalenes) were synthesized by optimizing reaction conditions (catalyst dosage, reaction time and temperature). The lubrication test results show that PEN–2 base oil with a large number of alkyl side chains exhibits good tribological properties and shows better wear resistance than the commercial alkylnaphthalenes base oil AN5, showing a good application prospect.
Abstract(23) HTML(15) PDF 4072KB(2)
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Ce0.8Cu0.2O2 oxygen carrier has excellent performance in chemical-looping reforming of methane coupled with CO2 reduction technology. Addition of different mass of S-1 molecular sieve to Ce0.8Cu0.2O2 oxygen carrier, and the oxygen resistance was characterized by XRD, BET, XPS, SEM, TEM and CH4-TPR&CO2-TPO. The physicochemical properties and reactivity of the carrier were studied. The effect of S-1 molecular sieve on the performance of Ce0.8Cu0.2O2 oxygen carrier in chemical-looping reforming of methane coupled with CO2 reduction was systematically investigated. Compared with Ce0.8Cu0.2O2 oxygen carrier alone, the specific surface area of the composite oxygen carrier increased from 15.44 m2 /g to 73.27 m2 /g after adding 0.3 g S-1 molecular sieve. At the same time, the thermal stability and structural stability have been greatly improved. The CH4 conversion rate of composite oxygen carrier with 0.3 g S-1 molecular sieve increased from 38.93% to 56.03%, and the CO yield increased from 1.18 mmol/g to 2.16 mmol/g during CO2 reduction.
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A series of Ca-Zr catalysts modified by different transition metals prepared by sol-gel method were studied for low temperature transesterification of methanol with propylene carbonate (PC) to dimethyl carbonate (DMC). The order of DMC selective of the catalyst was Co-Ca-Zr>Cu-Ca-Zr>Ca-Zr>Fe-Ca-Zr>Ni-Ca-Zr>Zn-Ca-Zr. Among them, the highest PC conversion (84.3%) and DMC selectivity (94.5) was obtained over Co-Ca-Zr catalyst under the reaction conditions of 35 ℃, reaction time of 2 h, methanol to PC molar ratio of 15, and catalyst dosage of 4%. The physicochemical properties of the catalysts were characterized by means of XRD, FT-IR, XPS and CO2-TPD. The results showed that the surface basic content and the percentage of strong basic sites of the catalyst were the main factors affecting the catalytic activity. Increasing the basicity of catalyst might lead to increased PC conversion but decreased selectivity of DMC. The catalyst modified with Co had the lowest surface basic content, the highest percentage of strong basic sites and thus the highest PC conversion and DMC selectivity.
Abstract(22) HTML(8) PDF 2434KB(3)
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The structure of the supports can significantly affect the Fischer-Tropsch catalyst activity and selectivity. The porous structure can improve the mass transfer of reactants, enhance the CO conversion activity and C5 + product selectivity; the high specific surface area is beneficial to disperse the loaded metal, improve the catalyst metal utilization efficiency and catalyst stability. However, it is relatively difficult for supports to obtain high specific surface area and macropore structure characteristics simultaneously. A mesoporous (2.9 nm) -macroporous (63.8 nm) bi-porous silica (BP-SiO2) support with a high specific surface area of 1103.2 m2/g was synthesized by the structure-directed hydrolysis method, and its catalytic performance for Fischer-Tropsch synthesis was investigated. The results showed that compared to the Co/SBA-15 catalyst with equivalent mesopore diameter, the catalyst Co/BP-SiO2 showen CO conversion rate nearly increased by 33.3%, CH4 selectivity reduced by 30.1%, improved C5 + selectivity and stability.
Abstract(70) HTML(24) PDF 29131KB(14)
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Fe-based Fischer-Tropsch synthesis (FTS) catalysts usually exist as the oxide precursor α-Fe2O3, which have different catalytic activities after being transformed to FexCy under different pretreatment conditions, so it is critical to study the pretreatment process of α-Fe2O3 for whole FTS reaction. However, the phases of Fe-based catalysts in such a process are highly dynamic and complex, and conventional characterizations cannot capture the accurate real-time information in the pretreatment reaction. Therefore, it is necessary and desired to apply various in-situ characterizations in this process, because they can obtain the dynamic changes of phase, morphology, surface structure and properties of the catalyst. And then a relationship between the pretreatment process and the subsequent catalytic performance of FTS will be effectively and reasonably established. This review presents a systematic summary of the experimental and data processing methods in in-situ characterizations of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy and Raman spectroscopy during the pretreatment of Fe-based FTS catalysts. These characterizations can clarify the complex structure and surface property changes of catalyst precursors and thus will facilitate the design and development of more efficient Fe-based FTS catalysts.
Abstract(14) HTML(6) PDF 6064KB(3)
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Direct synthesis of liquefied petroleum gas from syngas via Fischer-Tropsch synthesis route was systematically investigated over a nano-level core@shell catalyst. We introduced an incorporation of FeMg catalyst into mesoporous silica shell, with a further modification of Cu particles on the silica surface. The modified Cu/FeMg@SiO2 nano core-shell catalysts were synthesized by the combination of co-precipitation, modified sol-gel and facile impregnation methods. The as-synthesized catalysts’ physicochemical property was characterized by XRD, TEM, N2 adsorption-desorption, H2-TPR, XPS and CO2-TPD techniques. The catalytic performance of Cu/FeMg@SiO2 catalyst shows a high CO conversion of 96.6%, rather low CO2 selectivity of 21.9% and considerable LPG selectivity of 37.9%. The catalytic results indicate that the SiO2 shell restrains the formation of CH4 and contributes to increasing long-chain products. Meanwhile, the enhanced CO conversion of Cu/FeMg@SiO2 was ascribed to the active metal Cu dispersed on SiO2 shell, which also promoteolefin hydrogenation and cracking of C${}^+_5$ hydrocarbons products. The proposed catalyst preparation method will provide a new strategy for the synthesis of nano level catalyst with combinations of metal- and zeolite-based catalyst.
Abstract(44) HTML(20) PDF 1532KB(5)
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Pyrolysis is an important technology for the harmless reduction of food waste. In this paper, thermogravimetric analysis was used to analyze the pyrolysis characteristics of three typical seafood wastes, namely fish bones, crab shells, and shrimp shells, and to study the characteristic parameters of the pyrolysis process at different heating rates (20, 40, and 60 ℃/min), to analyze the effect of different components on the pyrolysis characteristics of seafood waste. The kinetic analysis of the pyrolysis process was carried out based on the pyrolysis characteristic parameters, combined with the apparent kinetic parameters and the fitting effects of various mechanism models were compared, and a more suitable mechanism model for the pyrolysis process of seafood waste was determined. The results showed that the pyrolysis processes of the three seafood wastes were closely related to their components, and the comparative analysis of TG-DTG curves found that the content of organic matter and inorganic salts were important factors affecting the pyrolysis process. The pyrolysis characteristic parameters of the three seafood wastes showed a consistent increasing trend with the increase of the heating rate. The main pyrolysis process of fish bones conforms to the first-order chemical reaction mechanism, and the organic matter decomposition stage of crab shells and shrimp shells can be described by a 1.5-order chemical reaction process. The large amount of chitin in shrimp shells and crab shells is the main reason for the difference in the order of chemical reactions. The activation energy increases with the increase of the heating rate, while the increment of the activation energy [i]gradually decreases. It could be presumed that the adoption of larger heating rates over 40 ℃/min would probably not arise more severe pyrolysis condition, which would be more economical from technical view. The results achieved in this paper may provide some fundamentals for competitive technology development for seafood wastes pyrolysis and carbonization.
2023, 51(2): 1-8.
Abstract(9) HTML(5) PDF 22917KB(7)
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2023, 51(2): 129-144.   doi: 10.19906/j.cnki.JFCT.2022076
Abstract(57) HTML(24) PDF 17523KB(16)
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"Thermal Dissolution based Carbon Enrichment" (TDCE) is the thermal extraction of lignocellulosic biomass wastes using non/weak polar organic solvents under mild conditions (350 °C, nitrogen atmosphere). After a series of deoxygenation and aromatization reactions, the obtained target solid products Soluble and Deposit have the advantages of anhydrous, ashless, high calorific value, etc. At the same time, this technology also has the advantages that the solvent does not participate in the chemical reaction and can be recycled and reused. Therefore, thermal solution carbon enrichment is one of the effective ways to realize biomass energy conversion. This paper firstly introduces various ways of biomass utilization at present; and then focuses on the factors affecting carbon-enrichment, reaction mechanism and product utilization pathways of biomass thermal solution. Under the background of the national strategy of "carbon neutrality", biomass thermal solution carbon-enriching technology has obvious economic value and social significance.
2023, 51(2): 145-154.   doi: 10.1016/S1872-5813(22)60033-1
Abstract(81) HTML(24) PDF 2568KB(23)
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Combining with the characteristics of high yield of mineral humic acid (HA) and high activity of biochemical HA, co-thermal oxidation of low rank coal and biomass to produce complex HA (MIXHA) was newly proposed. The mixture (MIX) of Heilongjiang lignite (HL) and wheat straw (WS) was co-thermally oxidized in 10% HNO3 solution to prepare MIXHA. This work focused on comparison of the macro morphology and microstructure of MIXHA between HLHA and WSHA by SEM, FT-IR and 13C NMR analyses, and explored the synergistic effect between HL and WS during the co-thermal oxidation process. The results show that MIXHA content is higher than the theoretical value. Decomposition of HNO3 molecular produces active oxygen atoms and nitrogen oxides to attack the molecular structure of WS and HL. Due to hydrogen bond rearrangement, glycosidic bond rupture, and crosslinking, plenty of alkyl radicals generated in WS are combined with the condensation aromatic ring in HL. Thus, the protonated aromatic carbon is changed into aliphatic substituted aromatic carbon. The obtained MIXHA is rich in oxygen-containing functional groups, and has high activity. Obvious characteristic peaks are observed in FTIR spectra of MIXHA. This work would provide a new idea for classification and resource utilization of low-rank coal and agricultural and forestry wastes.
2023, 51(2): 155-164.   doi: 10.1016/S1872-5813(22)60018-5
Abstract(83) HTML(50) PDF 1673KB(23)
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In this study, a series of catalysts with different Fe3O4 to iron carbide ratios were obtained by carburizing the α-Fe2O3 precursor prepared by co-precipitation method, under various carburization conditions. XRD, Mössbauer spectroscopy, XPS, and Raman spectroscopy were used to characterize the bulk and surface phase compositions of the Fe-based catalysts. The results show that increasing the carburization temperature and prolonging the carburization time lead to higher iron carbide concentration. To explore the active phase of CO2 formation, the catalysts were tested under different reaction conditions by tuning either CO conversion or H2O partial pressure. It turns out that the catalytic performance of the Fe-based catalyst in the FTS and water-gas shift (WGS) reactions is influenced by both the content of iron carbide and the degree of carbon deposition. Under typical Fischer-Tropsch reaction condition, the CO2 selectivity is determined by the CO conversion rather than the Fe3O4 content in the catalyst, meaning that the WGS reaction is here limited by the kinetic factors. On the contrary, adding H2O to the reaction gas results in the trend that higher CO2 selectivity is promoted by higher content of Fe3O4 in the Fe-based catalyst. It seems that Fe3O4 is the main active phase for the WGS reaction in the iron-based catalyst for FTS. These results provide a new insight into the active phase of CO2 generation on the Fe-based catalysts, which could be the theoretical basis for the design of new industrial FTS catalysts with low CO2 selectivity.
2023, 51(2): 165-174.   doi: 10.19906/j.cnki.JFCT.2022045
Abstract(61) HTML(21) PDF 16805KB(15)
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The NiMo catalysts were prepared using the mechanical ball milling method, and their structures were characterized by XRD and XPS to investigate the effects of the Ni/(Ni+Mo) ratio on catalyst composition and structure, as well as the performance of phenanthrene hydrogenation. The results show that the catalysts prepared by this method have good dispersion of active components Ni and Mo, and are mesoporous catalysts with a concentrated pore size distribution in the range of 2−10 nm. The specific surface area and MoIV content of the catalysts increase first and then decrease as the Ni/(Ni+Mo) ratio increases, both reaching maximum values at 0.33. The moderate amount of Ni promotes Mo sulfidation to form the NiMoS active phase, while the excessive amount of Ni forms NixSy, which covers active sites and reduces the hydrogenation activity. When the Ni/(Ni+Mo) ratio maintains at 0.33, the specific surface area of the catalyst decreases as Ni and Mo content increases, while MoIV content shows an increase trend. Raising the amount of sulfurizing agent ammonium thiosulfate (ATS) could increase both the specific surface area and MoIV content of the catalyst. It is observed that the effect of the Ni/(Ni+Mo) ratio on phenanthrene conversion is consistent with the MoIV content of catalyst, and the maximum value of 74.7% is obtained at the Ni/(Ni+Mo) ratio of 0.33. This further rises to 96.5% when the Ni and Mo contents and S/Mo ratio increase to 4.8%, 16% and 4.5, respectively. Meanwhile, the total selectivity and yield of octahydrophenanthrene and perhydrophenanthrene reach 83.9% and 80.9%, respectively. Furthermore, perhydrophenanthrene is mainly formed by hydrogenation of side ring of phenanthrene.
2023, 51(2): 175-185.   doi: 10.1016/S1872-5813(22)60034-3
Abstract(74) HTML(16) PDF 15583KB(20)
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ZSM-23 zeolite was successfully synthesized in a dual-template system, and ZSM-23-Al2O3 composites with different ratios were also prepared. The hydroisomerization performance of Pt/ZSM-23 catalyst was manipulated by introducing Al2O3, and the influence of Al2O3 on physicochemical properties was investigated by XRD, SEM, TEM, N2 physical adsorption-desorption and NH3-TPD characterizations. The results showed that Al2O3 improved the dispersion of Pt, significantly reduced the acid sites concentration of the catalyst, and regulated the metal-acid balance in quantitative. The suitable metal-acid balance concentration could improve the selectivity of isomers and suppress the cracking reactions. Meanwhile, Al2O3 dispersed the ZSM-23 grains, which improved the dispersion and increased the number of exposed pores in ZSM-23. Thus the diffusion efficiency of reactants and intermediates could be promoted and the isomer products selectivity could be improved. All composite catalysts showed high selectivity of isomer products, among which, Pt/(9Z-1Al) had the highest yield of isomer products due to its suitable metal-acid concentration balance, reached 60% at 340 ℃, which was a significant improvement compared with Pt/ZSM-23 (42%). When the reaction temperature was lower than 310 ℃, the pore mouth mechanism dominated in Pt/ZSM-23, while the key-lock mechanism was significantly strengthened at higher reaction temperature. After the introduction of Al2O3, more adjacent pores in ZSM-23 were exposed and the key-lock mechanism became the domination, which led to a large number of 7/8Me-C15 isomers.
2023, 51(2): 186-196.   doi: 10.1016/S1872-5813(22)60042-2
Abstract(54) HTML(18) PDF 12793KB(19)
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A highly efficient cerium-modified Cu/hexagonal mesoporous silica (xCe-Cu/HMS) catalyst for the vapor-phase hydrogenation of dimethyl oxalate (DMO) into ethylene glycol (EG) was prepared using an ammonia evaporation method. The Ce promoter can significantly improve the performance of the catalyst, and the best catalytic performance was obtained after the introduction of 1.2% Ce promoter on Cu/HMS. The DMO conversion and EG selectivity got to 99.6% and 96.3%, respectively, under moderate conditions (200 °C, 2.0 MPa, H2/DMO = 100 and LHSVDMO = 1.2 h−1). Characterization results revealed that Ce modification can enhance the interaction between Cu and the support, improve the dispersion of Cu on HMS, and maintain the appropriate ratio of Cu+/(Cu++Cu0). In this study, a simple and low-cost method was used to synthesize Ce-modified Cu-HMS catalysts, which showed excellent catalytic performance in conversion of DMO to EG under moderate conditions.
2023, 51(2): 197-204.   doi: 10.1016/S1872-5813(22)60052-5
Abstract(35) HTML(10) PDF 3722KB(17)
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Hydrogen production from electrolyzed water driven by sustainable energy is an effective way to achieve the hydrogen economy with zero carbon emission. Alkaline electrocatalytic hydrogen evolution reaction (HER) is one of the main energy transforming processes in the field of electrolytic water technology. The development of active and cost-effective nonprecious catalytic electrodes is of great importance to alkaline hydrogen evolution reaction. Amorphous nanosized nickel-boron alloy particles (NiB-COS) have been obtained by using chitosan oligosaccharides (COS) as a stabilizer via chemical reduction method. The as-prepared electrocatalysts have been used for the hydrogen evolution reaction (HER). The electrocatalysts have been characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma analysis (ICP) and X-ray photoelectron spectroscopy (XPS). NiB-COS displays a significant increase in hydrogen evolution reaction properties in alkaline media, affording low overpotentials of 49.4 mV at 10 mA/cm2 and 15.1 mV onset overpotential for the hydrogen evolution reaction. Tafel slope of NiB-COS is 86.1 mV/dec. Remarkably, the formation of a nickel-boron alloyed phase and the decrease of particle size are helpful to improve HER activity of NiB-COS. The experimental data indicated that the NiB-COS showed excellent long-term stability as a very active electrocatalyst.
2023, 51(2): 205-214.   doi: 10.1016/S1872-5813(22)60036-7
Abstract(61) HTML(27) PDF 5863KB(17)
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In this work we report the feasible modification of graphitic carbon nitride (g-C3N4) polymer through a post-functionalization progress. The resultant photocatalyst exhibits boron doping and mesoporous structure with a high surface area of 125 m2/g, leading in an increased surface activity for photocatalytic water splitting reaction. X-ray diffraction, X-ray photoelectron spectroscopy, PL emission spectra and UV-Vis spectra were used to detect the properties of as-prepared samples. Based on X-ray photoelectron spectroscopy analysis, boron is proposed to dope in the g-C3N4 lattice. Optical studies indicated that boron doped g-C3N4 exhibits enhanced and extended light absorbance in the visible-light region and a much lower intensity of PL emission spectra compared to pure g-C3N4. As a result, boron doped g-C3N4 shows activity of 10.2 times higher than the pristine g-C3N4 for photocatalytic hydrogen evolution. This work may provide a way to design efficient and mesoporous photocatalysts through post modification.
2023, 51(2): 215-224.   doi: 10.19906/j.cnki.JFCT.2022042
Abstract(28) HTML(25) PDF 12152KB(14)
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In this experiment, a Z-scheme nitrogen-deficient graphite-phase carbon nitride (LaFeO3/CQDs-g-C3Nx) composite photocatalyst was prepared. The catalyst was characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection (UV-Vis DRS), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that the introduction of nitrogen defects and CQDs enhanced the migration efficiency of photogenerated carriers. The photocatalytic degradation rate of LaFeO3/CQDs-g-C3Nx composites for rhodamine B (RhB) was 3.98 times higher than that of pure g-C3N4, and had good photocatalytic stability. It also showed good degradation of antibiotics and other organic pollutants.
2016, 44(7): 777-783.
[Abstract](323) [FullText HTML](190) [PDF 2169KB](36)

2016, 44(4): 385-393.
[Abstract](289) [FullText HTML](241) [PDF 1138KB](36)

2016, 44(3): 263-272.
[Abstract](180) [FullText HTML](166) [PDF 1275KB](21)

2016, 44(3): 279-286.
[Abstract](273) [FullText HTML](227) [PDF 12189KB](22)

2016, 44(7): 801-814.
[Abstract](542) [FullText HTML](349) [PDF 8665KB](57)

2018, 46(2): 179-188.
[Abstract](203) [FullText HTML](114) [PDF 7028KB](21)

2016, 44(9): 1034-1042.
[Abstract](297) [FullText HTML](180) [PDF 809KB](33)

2016, 44(11): 1388-1393.
[Abstract](274) [FullText HTML](193) [PDF 780KB](25)

2016, 44(6): 732-737.
[Abstract](251) [FullText HTML](169) [PDF 2776KB](24)

2018, 46(1): 92-98.
[Abstract](149) [FullText HTML](72) [PDF 865KB](21)

2013, 41(08): 1003-1009.
[Abstract](2205) [PDF 13334KB](38)
Abstract:
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.
2009, 37(04): 501-505.
[Abstract](1622) [PDF 1335KB](34)
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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.