An energy-effective polyaniline coated graphite felt (PANI@GF) composite cathode for the elec- tro-Fenton (E-Fenton) process was synthesized through an electro-polymerization method. The electrocatalytic activity ...An energy-effective polyaniline coated graphite felt (PANI@GF) composite cathode for the elec- tro-Fenton (E-Fenton) process was synthesized through an electro-polymerization method. The electrocatalytic activity of the cathode for the 2e- ORR process was investigated and dimethyl phthalate (DMP) was used as a model substrate to evaluate its performance in the E-Fenton process. The as-prepared PANI@GF composite possessed a three-dimensional porous structure, which is favorable for 02 diffusion, while the large amount of N atoms in the conductive polyaniline (PANI) enhanced 2e- ORR reactivity. The DMP degradation of the E-Fenton system using PANI@GF was significantly enhanced owing to the improvement in ORR performance. The apparent kinetic con- stant for DMP degradation was 0.0753 min-1, five times larger than that of GF. The optimal carboni- zation temperature and polymerization time for the preparation of the PANI@GF composite cath- ode was found to be 900 ℃ and 1 h, respectively. Measurement conditions are a crucial factor for proper evaluation of cathode electrocatalytic performance. Accordingly, the 02 flow rate, Fe^2+ con- centration, and pH for DMP degradation were optimized at 0.4 L/min, 1.0 mmol/L, and 3.0, respec- tively. These results indicate that the present PANI@GF composite cathode is energy-effective and promising for potential use as an E-Fenton system cathode for the removal of organic pollutants in wastewater.展开更多
The study concerns the use of MgCl2-supported high-activity Ziegler-Natta catalysts for the polymerization of ethylene.In particular,two types of catalysts were investigated,which were N-catalyst(BRICI)and improved ...The study concerns the use of MgCl2-supported high-activity Ziegler-Natta catalysts for the polymerization of ethylene.In particular,two types of catalysts were investigated,which were N-catalyst(BRICI)and improved polyethylene catalyst.The effects of catalyst structure on kinetic behavior were examined.The distribution of active centers in these catalysts was investigated by energy dispersive analysis by X-rays(EDAX),and morphologies of catalyst particles and polymer products were examined by scanning electron microscope(SEM).Hydrogen response and copolymerization performance were investigated and compared with the two catalysts.The results were correlated with the kinetic behavior of the two catalysts and appropriate models for polymer particle growth were presented.The improved polyethylene catalyst showed higher activity,better hydrogen response and copolymerization performance.展开更多
A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and ...A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.展开更多
Three sulfonyl aliphatic amines [(R2SO2)2NR1, viz.: compound 1, in which RI=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which RI=C8H17, and R2=CF3], have been synthesized and employe...Three sulfonyl aliphatic amines [(R2SO2)2NR1, viz.: compound 1, in which RI=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which RI=C8H17, and R2=CF3], have been synthesized and employed as internal electron donors (IED) for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the A1/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.展开更多
A novel MgCl2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was prepared and propylene polymerizations with the combination of such catalyst and four external donors were investigated ...A novel MgCl2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was prepared and propylene polymerizations with the combination of such catalyst and four external donors were investigated in detail. The catalyst was compared with a commercial one with phthalate as internal donor in terms of catalytic activity, hydrogen sensitivity and stereospecificity in propylene polymerization. The molecular weight,molecular weight distribution and microstructure of the produced polypropylenes were compared also. It was found that the novel catalyst containing succinate internal donor showed higher activity and higher stereospecificity than those with phthalate as internal donor. Consequently, polypropylenes obtained by the succinate-based catalyst showed high molecular weight, high melting temperature, high isotactic index and broad molecular weight distribution than those obtained with the commercial catalyst.展开更多
Poly (methyl methacrylate) (PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization (SI-ATRP). Energy disperse spectroscopy (EDS) and atomic force microsco...Poly (methyl methacrylate) (PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization (SI-ATRP). Energy disperse spectroscopy (EDS) and atomic force microscopy (AFM) confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69~. It is found that CuCI/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine (HMTETA) system is more suitable than CuBr/N, N, N′, N″, N′″-pentamethyl diethylenetriamine (PMDETA) system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuC1/HMTETA due to higher activity and better reversibility of the former system.展开更多
Porous organic polymers(POPs) have recently emerged as promising candidates for catalyzing oxygen reduction reaction(ORR).Compared to conventional Pt-based ORR catalysts, these newly developed porous materials, includ...Porous organic polymers(POPs) have recently emerged as promising candidates for catalyzing oxygen reduction reaction(ORR).Compared to conventional Pt-based ORR catalysts, these newly developed porous materials, including both non-precious metal based catalysts and metal-free catalysts, are more sustainable and cost-effective. Their porous structures and large surface areas facilitate mass and electron transport and boost the ORR kinetics. This mini-review will give a brief summary of recent development of POPs as electrocatalysts for the ORR. Some design principles, different POP structures, key factors for their ORR catalytic performance, and outlook of POP materials will be discussed.展开更多
In this paper,we synthesized cathode catalysts(PANI-PPYR,Fe/PANI-PPYR,Co/PANI-PPYR and Fe-Co/PANI-PPYR)with high performance oxygen reduction by using a simple heat treatment process.These catalysts were fabricated by...In this paper,we synthesized cathode catalysts(PANI-PPYR,Fe/PANI-PPYR,Co/PANI-PPYR and Fe-Co/PANI-PPYR)with high performance oxygen reduction by using a simple heat treatment process.These catalysts were fabricated by directly calcining the Fe and/or Co doped polyaniline(PANI)-polypyrrole(PPYR)composites.Their electrocatalytic activity for ORR both in acidic and in alkaline media was investigated by voltammetric techniques.Among the prepared catalysts,Co/PANI-PPYR presents the most positive ORR onset potential of 0.62 V(vs.SCE)in 0.5 mol/L H2SO4 solution or?0.09 V(vs.SCE)in 1 mol/L NaOH solution.In addition,the Co/PANI-PPYR catalyst shows the largest limiting-diffusion current density for ORR,which is 4.3 mA/cm2@0.2 V(vs.SCE)in acidic and 2.3 mA/cm2@?0.3 V(vs.SCE)in alkaline media.In acidic media,a four-electron reaction of ORR on the Co/PANI-PPYR and Fe/PANI-PPYR catalysts is more dominant than a two-electron reaction.In alkaline media,however,a four-electron and a two-electron mechanisms are co-present for the ORR on all the prepared catalysts.Co/PANI-PPYR catalyst also presents good electrocatalytic activity stability for ORR both in acidic and in alkaline media.展开更多
基金supported by the Sino-Greek Science and Technology Cooperation Project (2013DFG62590)the National Natural Science Foundation of China (21575299, 21576300, 21276290)+1 种基金Guangdong Province Nature Science Foundation (2014A030313150)Guangzhou Science and Technology Plan Project (201607010104)~~
文摘An energy-effective polyaniline coated graphite felt (PANI@GF) composite cathode for the elec- tro-Fenton (E-Fenton) process was synthesized through an electro-polymerization method. The electrocatalytic activity of the cathode for the 2e- ORR process was investigated and dimethyl phthalate (DMP) was used as a model substrate to evaluate its performance in the E-Fenton process. The as-prepared PANI@GF composite possessed a three-dimensional porous structure, which is favorable for 02 diffusion, while the large amount of N atoms in the conductive polyaniline (PANI) enhanced 2e- ORR reactivity. The DMP degradation of the E-Fenton system using PANI@GF was significantly enhanced owing to the improvement in ORR performance. The apparent kinetic con- stant for DMP degradation was 0.0753 min-1, five times larger than that of GF. The optimal carboni- zation temperature and polymerization time for the preparation of the PANI@GF composite cath- ode was found to be 900 ℃ and 1 h, respectively. Measurement conditions are a crucial factor for proper evaluation of cathode electrocatalytic performance. Accordingly, the 02 flow rate, Fe^2+ con- centration, and pH for DMP degradation were optimized at 0.4 L/min, 1.0 mmol/L, and 3.0, respec- tively. These results indicate that the present PANI@GF composite cathode is energy-effective and promising for potential use as an E-Fenton system cathode for the removal of organic pollutants in wastewater.
文摘The study concerns the use of MgCl2-supported high-activity Ziegler-Natta catalysts for the polymerization of ethylene.In particular,two types of catalysts were investigated,which were N-catalyst(BRICI)and improved polyethylene catalyst.The effects of catalyst structure on kinetic behavior were examined.The distribution of active centers in these catalysts was investigated by energy dispersive analysis by X-rays(EDAX),and morphologies of catalyst particles and polymer products were examined by scanning electron microscope(SEM).Hydrogen response and copolymerization performance were investigated and compared with the two catalysts.The results were correlated with the kinetic behavior of the two catalysts and appropriate models for polymer particle growth were presented.The improved polyethylene catalyst showed higher activity,better hydrogen response and copolymerization performance.
基金Supported by National Natural Science Foundation of China (No. 20476080)Tianjin Natural Science Foundation (No. 07JCYBJC00600)
文摘A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.
基金the PetroChina for the financial support(Contract Number:08-07-01-20)
文摘Three sulfonyl aliphatic amines [(R2SO2)2NR1, viz.: compound 1, in which RI=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which RI=C8H17, and R2=CF3], have been synthesized and employed as internal electron donors (IED) for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the A1/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.
文摘A novel MgCl2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was prepared and propylene polymerizations with the combination of such catalyst and four external donors were investigated in detail. The catalyst was compared with a commercial one with phthalate as internal donor in terms of catalytic activity, hydrogen sensitivity and stereospecificity in propylene polymerization. The molecular weight,molecular weight distribution and microstructure of the produced polypropylenes were compared also. It was found that the novel catalyst containing succinate internal donor showed higher activity and higher stereospecificity than those with phthalate as internal donor. Consequently, polypropylenes obtained by the succinate-based catalyst showed high molecular weight, high melting temperature, high isotactic index and broad molecular weight distribution than those obtained with the commercial catalyst.
基金Project(21376271)supported by the National Natural Science Foundation of ChinaProject(2013)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,China+2 种基金Projects(CL12129,201310533008)supported by the Undergraduates Innovative Training Foundation of Central South University,ChinaProject(Z12060)supported by the Undergraduate Free Exploration Innovation Foundation of Central South University,ChinaProject(CSUZC2013008)supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘Poly (methyl methacrylate) (PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization (SI-ATRP). Energy disperse spectroscopy (EDS) and atomic force microscopy (AFM) confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69~. It is found that CuCI/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine (HMTETA) system is more suitable than CuBr/N, N, N′, N″, N′″-pentamethyl diethylenetriamine (PMDETA) system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuC1/HMTETA due to higher activity and better reversibility of the former system.
文摘Porous organic polymers(POPs) have recently emerged as promising candidates for catalyzing oxygen reduction reaction(ORR).Compared to conventional Pt-based ORR catalysts, these newly developed porous materials, including both non-precious metal based catalysts and metal-free catalysts, are more sustainable and cost-effective. Their porous structures and large surface areas facilitate mass and electron transport and boost the ORR kinetics. This mini-review will give a brief summary of recent development of POPs as electrocatalysts for the ORR. Some design principles, different POP structures, key factors for their ORR catalytic performance, and outlook of POP materials will be discussed.
基金supported by the National Natural Science Foundation of China(21376070,20876038)the Scientific Research Fund of Hunan Provincial Education Department(11K023)Hunan Provincial Natural Science Foundation of China(14JJ2096)
文摘In this paper,we synthesized cathode catalysts(PANI-PPYR,Fe/PANI-PPYR,Co/PANI-PPYR and Fe-Co/PANI-PPYR)with high performance oxygen reduction by using a simple heat treatment process.These catalysts were fabricated by directly calcining the Fe and/or Co doped polyaniline(PANI)-polypyrrole(PPYR)composites.Their electrocatalytic activity for ORR both in acidic and in alkaline media was investigated by voltammetric techniques.Among the prepared catalysts,Co/PANI-PPYR presents the most positive ORR onset potential of 0.62 V(vs.SCE)in 0.5 mol/L H2SO4 solution or?0.09 V(vs.SCE)in 1 mol/L NaOH solution.In addition,the Co/PANI-PPYR catalyst shows the largest limiting-diffusion current density for ORR,which is 4.3 mA/cm2@0.2 V(vs.SCE)in acidic and 2.3 mA/cm2@?0.3 V(vs.SCE)in alkaline media.In acidic media,a four-electron reaction of ORR on the Co/PANI-PPYR and Fe/PANI-PPYR catalysts is more dominant than a two-electron reaction.In alkaline media,however,a four-electron and a two-electron mechanisms are co-present for the ORR on all the prepared catalysts.Co/PANI-PPYR catalyst also presents good electrocatalytic activity stability for ORR both in acidic and in alkaline media.