NaOH活化法中碱炭比对孔结构和电化学性能的影响

采用沥青焦为原料,以NaOH化学活化法制备出不同碱炭比(R)系列活性炭.用氮气吸附和脱附等温线计算出BET比表面积、DFT孔径分布及孔容,并且通过直流循环充放电、循环伏安等表征方法研究了其电化学性能.实验结果表明,R值对活性炭的BET比表面积、DFT孔径分布及孔容有良好的调控作用:当R=5时,其最大BET比表面积为1089m2/g,孔容达0.53cm3/g,当R=3时,其孔径分布在1.0-2.0nm百分比达36.2%;其直流循环充放电曲线较好,循环伏安曲线也近似矩形,表明具有良好双电子层电容器电极材料特性,在3mol/L的KOH电解液体系中,最大质量比电容、体积比电容、单位面积比电容分别达202F/g、143F/cm3、32.9μF/cm2;在1mol/L(C2H5)4NBF4/Propylene Carbonate(PC)电解液体系中,最大质量比电容、体积比电容、单位面积比电容分别达149F/g、107.3F/cm3、20μF/cm2.对KOH和(C2H5)4NBF4/PC电解质吸附的最佳孔径分别为1.3nm,1.5nm左右.     

孔结构对煤基活性炭电极材料电化学性能的影响(英文)

以太西无烟煤为前驱体,NaOH为活化剂制备电化学电容器电极材料。采用N2吸附法及电化学测试对活性炭的孔结构和电化学性能进行了表征。在1mol/L(C2H5)4NBF4/碳酸丙烯酯有机电解液体系中,研究了孔结构对活性炭电极材料的电化学性能的影响。结果表明:以NaOH为活化剂可制备出比表面积943mol/L～2479mol/L、比电容57F/g～167F/g的活性炭电极材料。活性炭电极材料的比电容不仅取决比表面积,而且与活性炭的孔径分布有关。孔径为2nm～3nm的中孔的存在可以有效降低电解液的扩散阻力,提高电极材料比表面积的利用率,从而使电容器的电化学性能得到增强。     

卷绕式活性炭纤维布超级电容器的研究

以活性炭纤维布（activated carbon fibre cloth,ACFC）为电极材料,以1mol/L的Et4NBF4/PC为电解液,制备卷绕式ACFC超级电容器。利用BET测试ACFC的孔隙性,利用恒流充放电测试和漏电流测试对ACFC超级电容器的性能进行表征。结果表明,基于ACFC的超级电容器达到80F/g的比容,能量密度达到20.2Wh/kg,功率特性好、漏电流小,具有很好的产业化前景。     

高性能超级电容器用高比表面积、层次孔结构炭材料的简便制备(英文)

采用NaOH一步炭化-活化聚偏二氯乙烯(PVDC)简便制备出高比表面积、层次孔结构炭材料。该炭材料具有发达的微孔-中孔-大孔的层次孔结构,其比表面达到2 815 m·2g-1。独特的微结构使其在无机和有机电解液中都表现出高的比电容和优异的大电流性能。其在6 mol·L-1KOH电解液中以0.05 A·g-1电流充放电测得的比电容高达376F·g-1,电流密度增大到50A·g-1比电容还保持215 F·g-1。在有机电解液1 mol·L-1Et4NBF4/AN中的比电容也达到170 F·g-1(电流密度0.05 A.g-1),电流密度增大到20A·g-1比容量还保持124F·g-1。     

高比表面积活性炭基水系Na_2SO_4电化学电容器的制备

以石油焦为前驱体和KOH作为活化剂制备一种用于电化学电容器的高比表面积活性炭,采用廉价弱腐蚀性的Na_2SO_4电解液制备一种高电压的对称活性炭基水系电化学电容器,用N2吸附-脱附仪表征活性炭电极材料的孔结构参数,用循环伏安、恒流充放电和交流阻抗等电化学测试方法研究其电化学性能。研究结果表明,活性炭的比表面积为2855m~2/g,平均孔径为2.31nm;活性炭基水系电化学电容器在1.0mol/L Na_2SO_4电解液中扫描速率为2mV/s的比电容能达到188F/g,在功率密度为200W/kg时能量密度达到19.4Wh/kg,活性炭基水系电化学电容器在电压值为1.6V下展现了良好的循环性能,意味着Na_2SO_4电解液对开发能量密度高和环境友好的电化学电容器有着重要的意义。     

茶籽壳质活性炭的制备及其电化学性能

以茶籽壳为原料,以K2CO3作为活化剂,制备了新型活性炭。用氮气吸脱附法对活性炭的孔结构进行了分析。以活性炭为电极材料,6mol/L KOH溶液为电解液组装成超级电容器,利用恒电流充放电、循环伏安、交流阻抗等电化学测试方法研究其电化学性能。结果表明,活化后的茶籽壳炭,其比表面积高达1272m2/g,比电容高达150F/g,研究表明茶籽壳活性炭适用于超级电容器的电极活性材料。     

利用核桃壳制备高比表面积活性炭电极材料的研究

以核桃壳为原料,采用KOH活化法制备活性炭,并将其用作超级电容器电极材料。利用N2吸附和扫描电镜(SEM)表征活性炭的孔结构及表面形貌,系统研究碱炭比(KOH与核桃壳炭化料的质量比)对活性炭孔结构的影响,并采用恒流充放电及循环伏安等测定核桃壳活性炭电极材料在3mol/L KOH电解液中的电化学性能。结果表明,随着碱炭比的增大,活性炭的比表面积、总孔容及中孔比例先逐渐增大后稍有减小。当活化温度为800℃,活化时间为1h,碱炭比为4时,可制备出比表面积为2404m2/g,总孔容为1.344cm3/g,中孔比例为28.6%,孔径分布在0.7~3.0nm之间的高比表面积活性炭。该活性炭用作超级电容器电极材料具有良好的大电流放电特性和优异的循环性能,电流密度由50mA/g提高到5000mA/g时,其比电容由340F/g降低到288F/g,经1000次循环后,比电容保持率为93.4%。     

中间相炭微球/活性炭复合材料的电化学行为

以中间相炭微球( CMS)为核心材料,沥青为壳层材料前躯体,采用原位生成法制备了中间相炭微球/活性炭(AC)复合材料.将所制CMS/AC复合材料作为超级电容电池的负极材料,组装了模拟电容器和锂离子半电池.采用扫描电镜和X-射线衍射仪分析了材料的物理结构,并研究了CMS/AC复合材料的电化学行为进行研究.结果表明:CMS/AC复合负极材料在六氟磷锂/碳酸乙烯酯+碳酸二甲酯(LiPF6/EC+DMC)与四氟硼酸四乙基铵/乙腈( Et4 NBF4/AN)电解液中均表现出良好的电化学性能,其比电容在模拟电容器中达到25.8 F/g,在锂离子半电池中能达到306.6 mAh/g (0.2C);同时表现出良好的倍率性能和循环性能.     

超级电容器用中孔炭的研究

以石油焦为原料,运用化学活化法制备了超级电容器用高比表面积中孔活性炭。利用XRD、SEM和BET对实验制备的中孔炭进行了分析和表征。以实验制备的活性炭为超级电容器电极材料,利用恒流充放电测试对其电容特性进行了研究。结果表明,实验研制的活性炭的比表面积为1733m^2／g,中孔含量达到60．6％,在150mA／g的电流密度下其比容达到180F／g,而且基于实验研制的活性炭的超级电容器具有低内阻和良好的功率特性。     

炭前驱体对活性炭孔结构和电化学性能的影响

分别以毛竹和石油焦为炭前驱体,采用KOH活化法制备超级电容器用高比表面积活性炭材料,考察了碱/炭比对不同炭前驱体所制得的活性炭的孔结构、吸附性能和电容性能的影响。结果表明,在相同的碱/炭比下,竹基活性炭孔径2nm的微孔较发达,而石油焦基活性炭孔径在2～50nm的中孔率较高。在适宜的工艺条件下,以毛竹为炭前驱体可制得比表面积为2610.7m2/g,比电容为206F/g的活性炭材料;以石油焦为炭前驱体可制得比表面积为2597.9m2/g,比电容为213F/g的活性炭材料。     

双电层电容器用煤基活性炭的制备与电化学性能表征

以河南永城无烟煤为原料、KOH为活化剂制备了高比表面积的煤基活性炭,采用低温N_2吸附法对活性炭的比表面积、孔容及孔径分布进行了表征,并对其用作双电层电容器电极材料的电化学性能进行了系统测试.在KOH与煤的质量比为4:1、活化温度为800℃、活化时间为1h的条件下制备出的活性炭其比表面积高达3224m~2/g,总孔容达1.76cm~3/g,中孔率为57.95%.该活性炭电极在3mol/L KOH电解液中的比电容高达324F/g,且具有良好的循环性能,当电流密度为40mA/g时,经1000次循环后,比电容保持率超过92%,且其漏电流很小.     

Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation

Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.     

活性炭物理结构与其变压吸附分离瓦斯性能

活性炭(AC)在煤层瓦斯气体吸附分离上具有良好的应用前景。选用4种活性炭,利用77K氮气吸附表征了活性炭的物理性质。在自制的静态吸附装置上,测量了4种活性炭样品对瓦斯气(CH4/N2混合气体)在298K和318K时的平衡吸附量,结果发现4种活性炭对CH4/N2吸附能力有较大的差异。用Langmuir吸附方程关联实验数据,计算出4种活性炭在不同温度下对CH4/N2的分离因子。结合4种活性炭的物理性质以及其对CH4/N2的吸附量,分析了影响活性炭对CH4/N2的吸附量的因素。活性炭在变压吸附分离浓缩瓦斯时,应具备合适的孔径,比表面积和孔容越大越好。     

表面改性对活性炭孔结构及热电转换性能的影响

为探究表面改性对活性炭孔结构及热电转换性能的影响,使用HNO_3和KOH在不同条件下对活性炭进行表面改性,用N2吸附法和XRD图谱表征活性炭改性前后孔结构和石墨化程度的变化。结果表明,改性后活性炭的比表面积和孔容提高,平均孔径减小,并存在石墨晶体结构。干法改性活性炭的比表面积和总孔容由1 077.880m~2/g和0.763cm~3/g分别增加到1 635.268m~2/g和1.128cm~3/g,并且微孔的孔容增加。改性处理可以去除活性炭中的杂质。分别以改性前后活性炭为材料制备固体电极,KCl为电解液,测试活性炭电极的热电转换性能,发现改性后活性炭具有更高的热电转换性能。     

Characterization and use of high surface area activated carbons prepared from cane pith for liquid-phase adsorption

Carbonaceous adsorbents with controllable surface areas were chemically activated with KOH at 780 degrees C from char that had been carbonized from cane pith at 450 degrees C. The pore properties including the BET surface area, pore volume, pore size distribution, and mean pore diameter of these activated carbons were characterized and derived using the t-plot method based on N(2) adsorption isotherms. The activated cane pith carbons, with KOH/char ratios of 2-6, exhibited BET surface areas ranging from 912 to 2299 m(2) g(-1). The scanning electron microscopic (SEM) observations revealed that the surface morphology of honeycombed holes on all activated cane pith carbons was significantly influenced by the KOH/char ratio. The adsorption kinetics and equilibrium isotherms of acid blue 74, methylene blue, basic brown 1, p-nitrophenol, p-chlorophenol, p-cresol, and phenol from water at 30 degrees C on the activated carbons were studied. The adsorption kinetics were suitably described by a simplified kinetic model, the Elovich equation. All adsorption equilibrium isotherms were in agreement with the Langmuir equation, and were used to compare the covered area (S(c)/S(p)) of the activated carbons at different KOH/char ratios. The high-surface-area activated carbons were proven to be promising adsorbents for pollution control and for other applications.     

A simple and highly effective process for the preparation of activated carbons with high surface area

Activated carbons with high surface area were prepared by phosphoric acid as activation agent and rice husks as precursors. It was found that the characteristics of the activated carbons were influenced not only by the preparation but also by the post-processing method. The high surface area of the activated carbons was prepared under the optimum condition (50% H₃PO₄ with impregnation ratio of 5:1, activation temperature of 500 °C, activation time of 0.5 h, wash water temperature of 100 °C). SiO₂ content could affect the surface area of activated carbons, either. The lower SiO₂ content of the activated carbons, the higher pore volume the carbons had. The SiO₂ content was 11.2% when used the optimum condition. The explanation was that silicon element in rice husks reacted with H₃PO₄ to form silicon phosphate (SiP₂O₇), and it could be proved further by X-ray diffraction analysis, SiP₂O₇ could be removed by post-process.     

Surface properties of activated carbon treated by cold plasma heating

To modify the surface properties of activated carbon powders, we have applied the cold plasma treatment method. The cold plasma was used to be generated in the evacuated reactor vessel by 2.45 GHz microwave irradiation. In this paper, changes of surface properties such as distribution of acidic functional groups and roughness morphology were examined. By the cold plasma treatment, activated carbons with large specific surface area of ca. 2000 m²/g or more could be prepared in a minute. The amount of every gaseous organic compound adsorbed on the unit gram of treated activated carbons was more increased that on the unit gram of untreated carbons. Especially, the adsorbed amount of carbon disulfide was remarkably increased even if it was compared by the amount per unit surface area. These results suggest that the surface property of the sample was modified by the plasma treatment. It became apparent by observing SEM photographs that dust and impure particles in macropores of activated carbons were far more reduced by the plasma treatment than by the conventional heating in an electric furnace under vacuum. In addition, a bubble-like surface morphology of the sample was observed by AEM measurement. The amount of acidic functional groups at the surface was determined by using the Boehm's titration method. Consequently, the increase of lactone groups and the decrease of carboxyl groups were also observed.     

预炭化对KOH活化石油焦的结构及电容性能的影响

以不同温度炭化的石油焦为原料、KOH为活化剂制备电化学电容器用炭电极材料. 采用XRD、TEM和N₂吸附法对前驱体及活化产物的结构进行了表征, 并考察了样品的电化学性能. 结果表明: 通过调整前驱体的预炭化温度, 可实现对石油焦基活性炭的微晶结构和孔结构的调控, 分别制得无晶体特性的高比表面积活性炭和由大量类石墨微晶构成的低比表面积活性炭. 低表面积活性炭依靠充电过程中电解质离子嵌入类石墨微晶层间而实现能量存储, 具有比高比面积活性炭高10倍的面积比电容和更大的体积比电容.     

Adsorption of aqueous metal ions on cattle-manure-compost based activated carbons

The objective of this study is to examine the suitability and performance of cattle-manure-compost (CMC) based activated carbons in removing heavy metal ions from aqueous solution. The influence of ZnCl₂ activation ratios and solution pH on the removal of Cu(II) and Pb(II) were studied. Pore texture, available surface functional groups, pH of point zero charge (pH_PZC), thermogravimetric analysis and elemental compositions were obtained to characterize the activated carbons. Batch adsorption technique was used to determine the metal-binding ability of activated carbons. The equilibrium data were characterized using Langmuir, Freundlich and Redlich–Peterson models. It was found that the uptake of aqueous metal ions by activated carbons could be well described by Langmuir equation. It is suggested that the increase of surface area and mesopore ratio as a result of increasing activation ratios favored the removal of Cu(II), while activated carbon rich in acidic groups showed selective adsorption towards Pb(II). The preferable removal of Cu(II) over Pb(II) could be due to the rich nitrogen content as well as the higher mesoporous surface area in the CMC activated carbons. The impregnated CMC activated carbons also showed a better performance for Cu(II) removal at varying solution pH than Filtrasorb 400 (F400), while a similar performance was observed for Pb(II) removal.