This paper investigates the degradation of chlorobenzene by dielectric barrier discharge(DBD)coupled with MnOx/γ-Al2O3 catalysts.MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characteri...This paper investigates the degradation of chlorobenzene by dielectric barrier discharge(DBD)coupled with MnOx/γ-Al2O3 catalysts.MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characterized in detail by N2 adsorption/desorption,x-ray diffraction and x-ray photoelectron spectroscopy.Compared with the single DBD reactor,the coupled reactor has a better performance on the removal rate of chlorobenzene,the selectivity of COx,and the inhibition of ozone production,especially at low discharge voltages.The degradation rate of chlorobenzene and selectivity of COx can reach 96.3%and 53.0%,respectively,at the specific energy density of 1350 J l-1.Moreover,the ozone concentration produced by the discharge is significantly reduced because the MnOx/Al2O3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene.In addition,based on analysis of the byproducts,the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.展开更多
A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts c...A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts calcined at different temperatures were characterized using NH3-TPD, pyridine-FTIR, X-ray diffraction, and Raman techniques. It was found that the calcination process could not only change the structure of these catalysts but also modify the amount of surface acidity on the catalysts. The catalyst calcined at 400 ℃ exhibited the highest conversion of acetylene （94.6%） and highest selectivity to vinyl fluoride （83.4%） and lower coke deposition selectivity （0.72%）. The highest activity was related to the largest amount of surface acidity on the catalyst, and the coke deposition was also related to the total amount of surface acidic sites.展开更多
The development of efficient systems for the catalytic oxidation of 2-nitro-4-methylsulfonyltoluene(NMST)to 2-nitro-4-methylsulfonyl benzoic acid(NMSBA)with atmospheric air or molecular oxygen in alkaline medium prese...The development of efficient systems for the catalytic oxidation of 2-nitro-4-methylsulfonyltoluene(NMST)to 2-nitro-4-methylsulfonyl benzoic acid(NMSBA)with atmospheric air or molecular oxygen in alkaline medium presents a significant challenge for the chemical industry.Here,we report the synthesis of FeOOH/Fe_(3)O_(4)/metal-organic framework(MOF)polygonal mesopores microflower templated from a MIL-88B(Fe)at room temperature,which exposes polygonal mesopores with atomistic edge steps and lattice defects.The obtained FeOOH/Fe_(3)O_(4)/MOF catalyst was adsorbed onto glass beads and then introduced into the microchannel reactor.In the alkaline environment,oxygen was used as oxidant to catalyze the oxidation of NMST to NMSBA,showing impressive performance.This sustainable system utilizes oxygen as a clean oxidant in an inexpensive and environmentally friendly NaOH/methanol mixture.The position and type of substituent critically affect the products.Additionally,this sustainable protocol enabled gram-scale preparation of carboxylic acid and benzyl alcohol derivatives with high chemoselectivities.Finally,the reactions can be conducted in a pressure reactor,which can conserve oxygen and prevent solvent loss.Moreover,compared with the traditional batch reactor,the self-built microchannel reactor can accelerate the reaction rate,shorten the reaction time,and enhance the selectivity of catalytic oxidation reactions.This approach contributes to environmental protection and holds potential for industrial applications.展开更多
Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub&...Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> was determined by nano-particle size analyzer, and the effects of nano-α-Al<sub>2</sub>O<sub>3</sub> content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al<sub>2</sub>O<sub>3</sub> dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al<sub>2</sub>O<sub>3</sub> increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al<sub>2</sub>O<sub>3</sub>.展开更多
separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed b...separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.展开更多
基金National Natural Science Foundation of China(No.21577023)the Special Research Project on Causes and Control Technology of Air Pollution(Nos.2017YFC0212905)the Science and Technology Innovation Action Project Supported by the Science and Technology Commission of Shanghai Municipality(No.18DZ1202605).
文摘This paper investigates the degradation of chlorobenzene by dielectric barrier discharge(DBD)coupled with MnOx/γ-Al2O3 catalysts.MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characterized in detail by N2 adsorption/desorption,x-ray diffraction and x-ray photoelectron spectroscopy.Compared with the single DBD reactor,the coupled reactor has a better performance on the removal rate of chlorobenzene,the selectivity of COx,and the inhibition of ozone production,especially at low discharge voltages.The degradation rate of chlorobenzene and selectivity of COx can reach 96.3%and 53.0%,respectively,at the specific energy density of 1350 J l-1.Moreover,the ozone concentration produced by the discharge is significantly reduced because the MnOx/Al2O3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene.In addition,based on analysis of the byproducts,the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.20873125）,
文摘A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts calcined at different temperatures were characterized using NH3-TPD, pyridine-FTIR, X-ray diffraction, and Raman techniques. It was found that the calcination process could not only change the structure of these catalysts but also modify the amount of surface acidity on the catalysts. The catalyst calcined at 400 ℃ exhibited the highest conversion of acetylene （94.6%） and highest selectivity to vinyl fluoride （83.4%） and lower coke deposition selectivity （0.72%）. The highest activity was related to the largest amount of surface acidity on the catalyst, and the coke deposition was also related to the total amount of surface acidic sites.
基金supported by the National Natural Science Foundation of China(22078251)Hubei Province Key Research and Development Program(2023DJC167)the research project of Hubei Provincial Department of Education(D20191504).
文摘The development of efficient systems for the catalytic oxidation of 2-nitro-4-methylsulfonyltoluene(NMST)to 2-nitro-4-methylsulfonyl benzoic acid(NMSBA)with atmospheric air or molecular oxygen in alkaline medium presents a significant challenge for the chemical industry.Here,we report the synthesis of FeOOH/Fe_(3)O_(4)/metal-organic framework(MOF)polygonal mesopores microflower templated from a MIL-88B(Fe)at room temperature,which exposes polygonal mesopores with atomistic edge steps and lattice defects.The obtained FeOOH/Fe_(3)O_(4)/MOF catalyst was adsorbed onto glass beads and then introduced into the microchannel reactor.In the alkaline environment,oxygen was used as oxidant to catalyze the oxidation of NMST to NMSBA,showing impressive performance.This sustainable system utilizes oxygen as a clean oxidant in an inexpensive and environmentally friendly NaOH/methanol mixture.The position and type of substituent critically affect the products.Additionally,this sustainable protocol enabled gram-scale preparation of carboxylic acid and benzyl alcohol derivatives with high chemoselectivities.Finally,the reactions can be conducted in a pressure reactor,which can conserve oxygen and prevent solvent loss.Moreover,compared with the traditional batch reactor,the self-built microchannel reactor can accelerate the reaction rate,shorten the reaction time,and enhance the selectivity of catalytic oxidation reactions.This approach contributes to environmental protection and holds potential for industrial applications.
文摘Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> was determined by nano-particle size analyzer, and the effects of nano-α-Al<sub>2</sub>O<sub>3</sub> content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al<sub>2</sub>O<sub>3</sub> dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al<sub>2</sub>O<sub>3</sub> increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al<sub>2</sub>O<sub>3</sub>.
基金supported by the National Natural Science Foundation of China (21203017)Open Fund of State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (N-11-3)+1 种基金Program for Liaoning Excellent Talents in University (LNET)the Funda-mental Research Funds for the Central Universities (DC201502020304)~~
文摘separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.
