Additivity of pore structural parameters of granular activated carbons derived from different coals and their blends

A series of granular activated carbons(GACs) were prepared by briquetting method from Chinese coals of different ranks and their blends,with coal pitch as the binder.Pore structural parameters including BET specific surface area(SBET),total pore volume(VT) and average pore diameter(da) were measured and calculated as well as process parameters such as yield of char(CY) and burn-off(B).The relationship between the pore structural parameters of the GAC from coal blend(BC-GAC) and the ones of the GACs from corresponding single coals(SC-GACs) was analyzed,in which an index,the relative error(d),was presented to define the bias between fitted values and experimental values of these parameters of the BC-GACs.The results show that the BC-GAC keeps qualitatively the pore structural features of the SC-GACs;as concerned as the quantitative relationship,the pore structural parameters of the BC-GAC from coal blend consisting of non-caking coals can be obtained by adding proportionally the pore structural parameters of the SC-GACs with d less than 10%.Meanwhile,for the BC-GAC from coal blend containing weak caking bituminous coal,the d increases up to 25% and the experimental pore size distribution differs greatly from the fitted one.     

Influence of KOH activation techniques on pore structure and electrochemical property of carbon electrode materials

1 INTRODUCTIONSupercapacitor is a kind of newenergy storagedevice , which can fill the gap between the conven-tional capacitor and the battery[1 ,2]. Supercapa-ciors are nowutilizedin many fields ,such as spaceindustry ,national defense ,warindustry ,electricalvehicle , wireless communication, and consume e-lectronics .It is well known that the electrode ma-terial is the key factor to determine the perform-ance of supercapacitor . At present ,the activatedcarbonis the main marketed availa…     

Preparation of activated carbons from mesophase pitch and their electrochemical properties

The influences of molar ratio of KOH to C and activated temperature on the pore structure and electrochemical property of porous activated carbon from mesophase pitch activated by KOH were investigated. The surface areas and the pore structures of activated carbons were analyzed by nitrogen adsorption, and the electrochemical properties of the activated carbons were studied using two-electrode capacitors in organic electrolyte. The results indicate that the maximum surface area of 3 190 m2/g is obtained at molar ratio of KOH to C of 5:1, the maximum specific capacitance of 122 F/g is attained at molar ratio of KOH to C of 4:1, and 800 ℃ is the proper temperature to obtain the maximum surface area and capacitance.     

Electrochemical behavior of wound supercapacitors with propylene carbonate and acetonitrile based nonaqueous electrolytes

The activated carbon wound supercapacitors with TEABF₄/propylene carbonate (PC) and TEABF₄/acetonitrile (AN) electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior were investigated by cyclic voltammetry (CV) and constant current charge-discharge. Compared with the PC-based supercapacitor, the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance (R _ES) at discharge currents ranging from 5 to 1 000 mA and 25 °C. Moreover, temperature effects are more prominent for PC-based supercapacitor than for AN-based supercapacitor. When the measurement temperature ranges from 60 °C to −40 °C the capacitance changes from 5.1 to 2.5 F and R _ES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance and R _ES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property. Foundation item: Project(20803095) supported by the National Natural Science Foundation of China; Project(2008AA03Z207) supported by the National High Technology Research and Development Program of China     

不同变质程度无烟煤制活性炭的研究

本文根据对变质程度不同的阳泉、晋城、孤堰山３种无烟煤制作活性炭的研究，探讨了不同变质程度无烟煤制作活性炭的差异，从而对不同无烟煤原料加工活性炭工艺提出合理建议。认为低变质无烟煤（ＷＹ３）适宜生产活性炭，并可采用直接活化法生产合格破碎炭；中变质无烟煤（ＷＹ２）可得到合格的柱状炭，要生产破碎炭则需较高的活化条件；高变质无烟煤（ＷＹ１）不适宜制作活性炭。     

水系和有机系活性炭超级电容器的性能研究

采用活性炭作为电极活性物质,以碳纳米管为导电剂,用聚四氟乙烯隔膜制备水系和有机系扣式超级电容器,考察并分析二者在容量特性、自放电性能、循环性能、功率密度、能量密度等方面的优劣。结果表明,实验制得的电容器样品表现出良好的电容行为和循环性能;水系电容器样品10h自放电率为28.7%,1h漏电流为0.32mA;有机系电容器样品在电流密度为1.04A/g时,能量密度为10.32Wh/kg,功率密度达到1.88kW/kg。     

Preparation and electrochemical characterization of activated carbons by chemical-physical activation

A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m²/g and 0.308 4 cm³/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance. Foundation item: Project(2007BAE12B01) supported by the National Key Technology Research and Development Program of China     

Catalytic hydrolysis of carbonyl sulfide over modified coal-based activated carbons by loading metal

A novel type of metal oxide/activated carbon catalyst was prepared by sol-gel method for the hydrolysis of carbonyl sulfide (COS). The influences of the calcination temperature, additive content (2.5%–10.0% Fe₂O₃, mass fraction) and the basic density of the activation process were thoroughly investigated. The surface of catalysts was characterized by Boehm titration. The products were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that catalysts with 2.5%–5.0% Fe₂O₃ after calcining at 500 °C have superior activity. The conversion rate of COS increases with increasing the relative density of basic capacity loaded onto activated carbon(AC), and the activity follows the order: KOH>Na₂CO₃>NaHCO₃. Boehm titration data clearly show that the total acidity increases (from 0.06 to 0.48 mmol/g) and the basic groups decrease (from 0.78 to 0.56 mmol/g) after COS hydrolysis and H₂S adsorption. The XPS results show that the product of H₂S may be absorbed by the interaction with metal compounds and O₂ to form sulfate (171.28 eV) and element sulfur (164.44 eV), which lead to catalysts poisoning.     

利用废轮胎热解炭制取活性炭的试验研究

热解炭是废轮胎热解的重要产物之一.以CO2气体作为活化剂对废轮胎热解炭制取活性炭的活化温度为820～950℃,活化时间为60～360 min.在试验条件下,活化温度越高,活化时间越长,活性炭烧失率越大,比表面积也越大.制得的活性炭具有与商业活性炭相似的中、大孔隙分布,而微孔则不发达,因此孔容积小于商业活性炭.在950℃,240 min条件下得到中等比表面积(306 m2/g)的活性炭.针对碘、苯酚和亚甲基蓝三种物质考察了活性炭的液相吸附特性.热解炭和活性炭对亚甲基蓝和苯酚具有良好的吸附性,而碘吸附值则与商业活性炭尚有较大差距.     

改性活性炭对水溶液中氟离子的吸附性能

选用氧化镁改性活性炭（MgO—AC）为新型吸附剂,用于去除水溶液中的氟离子．系统地研究了反应时间、吸附剂最佳投加量、pH、温度等因素对吸附剂除氟性能的影响情况．反应系统达到吸附平衡的时间为180min．吸附剂最佳投加量为2．8g／L．pH值是影响吸附过程的重要因素之一,本研究最佳反应pH范围为6．0—8．0．吸附等温线研究发现MgO—AC除氟剂吸附等温线方程均符合Langmuir吸附等温线模型,且吸附量随着温度的升高而升高．吸附动力学研究发现动力学数据较好的的符合伪二级动力学模型．本研究对MgO—AC除氟的机理进行了初步探讨．廉价以及较高的吸附性能等优点表明MgO—AC是一种有实际应用潜力除氟材料．     

Preparation of magnetically separable mesoporous activated carbons from brown coal with Fe_3O_4

Magnetically separable mesoporous activated carbon was prepared from brown coal in the presence of Fe_3O_4 as a bi-functional additive. Magnetic activated carbon(MAC) was characterized by lowtemperature nitrogen adsorption, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and vibrating sample magnetometry(VSM). The evolution behaviors and transition mechanism of Fe_3O_4 during the preparation of MAC were investigated. The results show that prepared MAC with 6 wt% Fe_3O_4 addition having a specific surface area and mesopore ratio of 370 m~2·g~(-1) and 55.7%, which meet the requirements of adsorption application and magnetic recovery. Highly dispersed iron-containing aggregates with the size of 0.1 lm in the MAC were observed. During the preparation of MAC, Fe_3O_4 could enhance the escape of volatiles during the carbonization. Fe_3O_4 could also accelerate burning off the carbon wall during activation, which leads to enlarging micropore size, then resulting in the generation of mesopore and macropore. As a result, a part of Fe_3O_4 converted into FeO, FeOOH, a-Fe, c-Fe, Fe_2 SiO_4 and compound of Aluminum-iron-silicon.The prepared activated carbon, which was magnetized by both of residual Fe_3O_4, reduced a-Fe and cFe, can be easily separated from the original solution by external magnetic field.     

Influence of nitrogen hetero-substitution on the electrochemical performance of coal-based activated carbons measured in non-aqueous electrolyte

Nitrogen-containing carbons were prepared by modification of activated carbons. The modified carbons were used as electrode materials with improved electrochemical performance. Precursor anthracite was activated by KOH (KOH: anthracite= 1:1), modified by melamine or urea and then treated at 1173 K to obtain the modified carbons. The porous structure, the chemical composition and the electrochemical characteristics of the carbons were investigated by nitrogen sorption, XPS and electrochemical methods respectively. Electrochemical experiments were performed in an organic electrolytic solution of 1 M (C2H5)4NBF4/PC.The samples modified by the different methods showed differences in chemical composition that introduced varying degrees of electrochemical performance enhancement. The presence of nitrogen enhanced the electron donor properties and the surface wettability of the activated carbons: this ensured a sufficient utilization of the exposed surface for charge storage.     

Preparation and characterization of LiAlxMn2-xO4 for a supercapacitor in aqueous electrolyte

LiAlxMn2-xO4(0≤x≤0.5) was synthesized by high temperature solid-state reaction. The structure and morphology of LiAlxMn2-xO4 were investigated by X-ray diffraction and scanning electron microscopy(SEM) . The results indicate that all samples show spinel phase. The polyhedral particles turn to club-shaped,then change to small spherical,and finally become agglomerates with increasing Al content. The supercapacitive performances of LiAlxMn2-xO4 were studied by means of galvanostatic charge-discharge,cyclic vol...     

Adsorption characteristics of carbon tetrachloride from aqueous solution onto polyacrylonitrile-based activated carbon fiber

The isotherm, mechanism and kinetics of carbon tetrachloride (CT) adsorption by polyacrylonitrile-based activated carbon fiber (PAN-ACF) were investigated in batch reactors and a continuous flow reactor, and the regeneration of PAN-ACF was also studied. Freundlich and Dubinin-Radushkevich (D-R) adsorption equations can well describe the adsorption isotherm. CT is mainly adsorbed on the exterior surface of PAN-ACF with low boundary layer effect and rate-controlling step of intra-particle diffusion. The adsorption dynamics in the batch reactor well fits with the pseudo-first-order model, and the breakthrough curves in the continuous flow reactor can be well described by the Yoon-Nelson model. The ACF can be recycled through thermal regeneration, whereas the adsorption capacity decreases from 7.87 to 4.98 mg/g after the fourth regeneration. 78%–94% of CT can be removed from the wastewater of a fluorine chemical plant on a pilot scale, which confirms the efficacy of ACF under industrial conditions. The results indicate that PAN-ACF is applicable to CT removal from wastewater.     

载锆颗粒活性炭吸附去除水溶液中的硫酸根离子

制备负载氧化锆的颗粒活性炭(Zr-GAC),以吸附水溶液中的硫酸根离子.采用扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和比表面积测定等方法对Zr-GAC进行表征.结果表明,Zr-GAC具有多孔的表面积,其上具有许多由氧化锆组成的团聚体.XPS分析证实,吸附剂表面存在大量的锆和羟基,氧化锆改性后...     

改性炭对磺胺甲噁唑的吸附及解吸特性

采用商品活性炭和金属氧化物改性炭作为吸附剂,研究了几种活性炭对磺胺甲噁唑(SMZ)的吸附及解吸特性。结果表明:SMZ在几种活性炭上的吸附动力学符合拟二级动力学方程;SMZ的吸附均可采用Freundlich、Langmuir和Langmuir-Freundlich模型进行拟合,Langmuir-Freundlich吸附模型能更好地描述活性炭和改性炭对SMZ的吸附行为;铁、锰氧化物的存在对活性炭的比表面或者孔结构影响不大,并且其对活性炭吸附水中SMZ的性能影响甚微;与AC-Fe和AC-Mn相比,AC-0上吸附的SMZ更易解吸,改性炭负载的金属氧化物与SMZ的表面络合作用增强了AC-Fe和AC-Mn对SMZ的化学吸附,并且改性炭的MnOx和FeOx能氧化降解部分SMZ。     

Optimal electrochemical performances of CO2 activated carbon aerogels for supercapacitors

Activated carbon aerogels（ACAs） derived from sol-gel polycondensation of resorcinol （R） and formaldehyde （F） were pyrolyzed under Ar flow and activated in CO2 atmosphere. The morphology of ACAs was characterized by scanning electron microscopy （SEM） and the structural properties were determined by N2 adsorption at 77 K. The results show that ACAs have a typical three-dimensional nanonetwork structure composing of cross-linking of carbon nanoparticles. The specific surface area and the total pore volume remarkably increase with increasing activation time while the previous porous structure still remains. The specific capacitance of the 950-10-ACA electrode can reach up to 212.3 F/g in 6 mol/L KOH electrolyte. The results of constant-current charge-discharge testing indicate that the ACAs electrodes present fast charge- discharge rate and long cycle life （about 98% capacitance retained after 3000 charge-discharge cycles at 1.25 mA/cm2）. Lower internal resistances can be achieved for 950-10-ACA electrode in KOH electrolyte. Our investigations are very important to improve the wettability and electrochemical performance of electrode for supercapacitors.     

外加电流阴极保护强化ACF激活PDS降解水中卡马西平

卡马西平是一种典型的持久性的有机药物污染物,采用一种新的外加电流阴极保护强化活性炭纤维(ACF)激活过硫酸盐(PDS)的高级氧化方法,实现对水中卡马西平的高效降解.考察该体系对比活性炭纤维激发过硫酸盐体系、阴极保护活性炭纤维电解体系、过硫酸盐体系、活性炭纤维吸附体系、电解体系等不同工艺对卡马西平的降解率,探究过硫酸盐初始浓度、电压、初始pH等因素对体系的影响,并通过活性炭纤维性质测定和自由基捕获探究其降解机制.结果显示,外加电流阴极保护增强活性炭纤维(ACF)激活过硫酸盐(PDS)体系对水中卡马西平的氧化降解率远高于其他5种处理工艺.在外加电流阴极保护强化活性炭纤维(ACF)激活过硫酸盐(PDS)体系中,过高的过硫酸盐浓度反而不利于卡马西平的降解,在一定条件下存在一个适宜的过硫酸盐浓度范围;电压的提高和初始pH为酸性(pH=3)更有利于对卡马西平的氧化降解.此外,该体系中活性炭纤维受到阴极电场保护,使用寿命大大延长.硫酸根自由基在体系去除卡马西平过程中起主导作用.     

载铁颗粒活性炭的制备及其表征

本文以废活性炭为原料,氧化铁为添加剂,通过高温煅烧的方法制备载铁颗粒活性炭（IOC-GAC）.结果表明,IOCGAC制备的最佳工艺参数为：煅烧终温为900℃,升温速率为6℃·min-1,m（氧化铁）/m（废活性炭）为4：6,恒温时间为0.5h,所得产品的比表面积达630.5m2·g-1,收率为50.9％.对其进行SEM,IR,XRD表征分析,结果表明活性炭的表面负载了一层致密的铁氧化物,且主要以α-Fe、Fe3O4或γ-Fe2 O3的形态存在,饱和磁化强度高达66.247 emu·g-1.     

纳米门炭结构及超级电容特性

以生石油焦为原料,采用KOH活化法制备纳米门炭。采用氮气吸附法、X射线衍射(XRD)和光电子能谱衍射(XPS)对其孔结构、微晶结构和表面性质进行分析,并以其为电极组装超级电容器,测试了电容特性。结果表明:纳米门炭可在3.5V电压下工作,通过首次充电过程中的电化学活化而获得较大的比电容。样品N900比表面积仅为61m2/g,但比电容确高达136.7F/g,能量密度高达58.1Wh/kg。