Electrophysical Properties and Heat Capacity of Shale from the Kendyrlyk Deposit

In this work, the chemical analysis of the initial and activated shale from the Kendyrlyk deposit of Kazakhstan is described. The activated shale was obtained in the high-temperature processes of carbonization and activation in the atmospheres of argon and water vapor, respectively. The electrophysical characteristics of the test shale were determined for first time by measuring the electrocapacity of samples in a temperature range of 293–483 K. The temperature dependences of the specific heat of shale were obtained by dynamic calorimetry. Based on the experimental data, equations for the temperature dependence of the heat capacity of shale were derived; these equations can be subsequently used for determining the thermal conductivity and thermal diffusivity of shale.     

兰炭基活性炭的制备工艺优化及吸附性能研究

以榆林某公司的兰炭为原料,KOH粉末为活化剂制备活性炭。通过改变活化过程中时间、温度、炭碱比等因素,从而探究活性炭的碘吸附能力。通过响应曲面优化处理活性炭制备过程中活化因素,从而确定最佳工艺。采用比表面积测定,红外光谱分析,扫描SEM电镜等对活性炭结构及性能表征进行分析结果表明,上述活化条件都会影响活性炭吸附能力和孔隙结构。当活化过程中的温度达到750℃,时间为0.5 h,炭碱比为1:3的时候,KOH的活化效果最佳,所制样品的碘吸附值最大且为1 162.91 mg/g,其BET比表面积可达655.15m2/g,Langmuir比表面积为908.22 m2/g。通过红外分析可知活性炭与预处理兰炭原料红外光谱图走势极其相似,只是活性炭出现了较强的芳基烷基醚C-O伸缩振动峰。通过扫描显微电镜分析可知与原料兰炭相比,活性炭样品组织表面非常粗糙并且有大量的孔隙出现,样品结构非常疏松。     

Study on synthesis of low surface area activated carbons using multi-step activation for use in electric double layer capacitor

Low surface area activated carbon derived from compact mesocarbon microbeads (MCMB2010) was synthesized using a lower amount of KOH (1:1 weight ratio of KOH to MCMB) than normally used followed by electrochemical activation. The specific capacitance of the activated carbon heat treated at between 650 and 900 °C was increased up to ca. 118 F/cc (half cell base, 750 °C-heat treated sample) after electrochemical activation, even with a low surface area carbon (<50 m²/g). The morphology of low surface area activated MCMB determined by FE-SEM showed a smooth carbon surface without pores. The charge/discharge profiles were similar to those of conventional activated carbon. The specific capacitance of the activated samples increased with increasing heat treatment up to 850 °C after electrochemical activation. However, it was lower for the sample heat treated at 900 °C.     

煤-生物质基活性炭成孔机制及其吸附乙酸乙酯的性能

以CO₂为活化气氛,通过一步快速热解活化法从黑山煤粉与生物质混合物中制取活性炭。讨论了不同质量比率、活化温度和CO₂浓度对活性炭比表面积的影响。通过N₂吸附（BET）、扫描电镜（SEM）、拉曼光谱（Raman）和红外光谱（FTIR）对活性炭的性能进行了表征。确定了制备活性炭的最佳条件为活化温度900℃、质量比1、CO₂体积分数30%、活化时间120min时,活性炭的比表面积和孔容最大,分别为901m²/g和0.39cm³/g。最后,用乙酸乙酯吸附量验证了其吸附性能,最大累积吸附量为766.51mg/g。     

Effect of precursor composition on the activation of pitchbased carbon fibers

Pure and silver-containing carbon fibers were prepared from isotropic pitch precursors supplied by Conoco, Inc., and a Korean research team and activated in carbon dioxide to varying degrees of burn-off. The specific activation rates for the carbon fibers were measured as well as the nitrogen adsorption characteristics of the activated carbon fibers. Scanning electron microscopy was used to investigate the surface morphology and the behavior of silver particles during the activation process. Molecular composition of the two pitch precursors was determined using a gas chromatograph mass spectrometer and a MALDI TOF mass spectrometer. Results showed that specific surface area increased with the burn-off, and the trends were similar for the pure and silver-containing fibers formed from both isotropic pitch precursors. However, the catalytic behavior of silver during activation, the activation rate, and even the pore characteristics of the activated fiber were found to be dependent on the molecular composition of the precursor pitch.     

不同活化法制备的焦化除尘灰基活性炭的性能比较

采用焦化除尘灰为原料,分别用水蒸气和KOH为活化剂制备焦化除尘灰基活性炭,并对所制的活性炭进行碘吸附值、BET比表面积、孔径分布、孔容以及表面形貌测试。实验结果表明,采用KOH活化法制备的活性炭吸附性能强于采用水蒸气活化法制备的活性炭。氢氧化钾活化法制备的活性炭为中孔孔型,BET比表面积达275.51 m2/g。     

活化温度对酚醛基活性炭纤维的孔结构和电化学性能的影响

从酚醛纤维出发,经过炭化和KOH活化制备了酚醛基活性炭纤维（PACF）,并对不同温度下活化样品的比表面积、孔结构以及所制备的双电层电容器（EDLC）的电化学性能之间的关系进行了探讨。氮气（77K）吸附法测定PACF活性炭纤维的孔结构和比表面积;采用循环伏安、交流阻抗、恒流充放电等测试对超级电容器的电化学性能进行了测试。结果表明：900℃是KOH活化酚醛纤维制备用于EDLC电极材料的最佳活化温度,该温度下活化样品具有最佳的循环性,稳定性和较小的内阻,比表面积为2311m^2·g^-1和比电容264．IF·g^-1（充放电电流为1000mA·g^-1）。PACF系列样品均呈现出典型的微孔炭的特征,不同活化温度下制备的PACF,虽然表现出不同的比表面积和比电容,但是其整体孔径分布范围基本相同,都在0.5nm～3．0nm之间。随活化温度的升高,样品的电容性能和功率特性越来越好,内阻也随活化温度的升高而降低。     

油茶壳微孔活性炭的制备及表征

以油茶壳为原料,经炭化、KOH活化,制备微孔活性炭。考查了活化温度、活化时间和碱炭比对微孔活性炭碘吸附值和产率的影响,并采用正交试验优化了制备条件。研究结果表明：活化温度800℃、活化时间180 min、碱炭质量比3.5：1时,活性炭的碘吸附值达3 221 mg/g,产率51.2%。采用比表面积孔隙分析仪测定了氮气吸附/脱附等温线,计算得BET比表面积为1 755.72 m²/g,平均孔径为2.15 nm,总孔容为0.328 cm³/g,微孔孔容占总孔容的55.8%;SEM分析可见活性炭表面具有大量孔隙结构;FT-IR分析表明活化促进了—CH₃、—OH热解,活性炭中仍保存含氧官能团。     

高比表面积煤质活性炭的制备与活化机理

以煤为原料,采用KOH活化法制备了高比表面积活性炭,分别考察了活化温度、浸渍比和活化时间等工艺参数对活性炭吸附性能的影响;测试了高比表面积活性炭在-196℃对N₂的吸附等温线、比表面积和孔径分布。结果表明,当活化工艺参数为活化温度900℃,浸渍比4,活化时间1.5 h的条件下可以制得较好的高比表面积活性炭产品,其比表面积为3135 m²·g^-1,孔容为1.72 cm³·g^-1,碘吸附值为2657 mg·g^-1;采用扫描电子显微镜观察了高比表面积活性炭的微观结构,采用气体分析仪检测了活化过程中的尾气成分,提出了高比表面积活性炭的活化机理。     

酚醛树脂基活性炭材料的制备及其电化学性能

以酚醛树脂（PF）为原料,聚乙二醇（PEG）为造孔剂,采用聚合物共混炭化及水蒸气活化法制备超级电容器电极用活性炭。通过热重（TG）分析探讨了PF、PEG及其共混物（PF-PEG）在升温过程中的热解行为,用N₂-BET法测试比表面积及其孔结构参数。通过测试恒流充放电、循环伏安和交流阻抗曲线分析其电化学性能,研究了活化温度、水蒸气流速及活化时间对活性炭孔结构及电化学性能的影响。结果表明,当活化温度为900℃、水蒸气流速为1 ml·min^-1、活化时间为2 h时制备的活性炭结构和性能相对较好,孔径主要分布在2 nm以下,比电容达到105.4 F·g^-1,具有良好的电容特性。     

Preparation of activated carbon from olive mill solid residue

A process was developed for producing high quality activated carbon from Algerian mill waste. The solid olive mill residue was carbonized at 800 °C and physically activated with CO₂, air or steam. An optimum activation temperature of about 850 °C was determined for all the activation agents used. Steam appeared to be the most efficient activator as compared with air and CO₂. An optimal activation time of about 2 h was then determined with steam as the optimum activation agent. The porous structure of the activated carbon was characterized by nitrogen adsorption at −196 °C, and in all cases the surface areas, calculated by DR and BET methods, confirmed the production of a material with good microstructural characteristics and specific surfaces exceeding 1500 m² g⁻¹ for the carbon prepared by steam activation. Phenol adsorption isotherms gave the adsorption properties and the adsorption capacity of about 11.24 mg of phenol per gram of the activated carbon produced. The kinetics of the phenol adsorption onto the porous material was evaluated by means of two models: the external resistance model and the linear model. The second model appeared to constitute a more appropriate fit for the experimental data. © 2000 Society of Chemical Industry     

Role of active sites in the steam activation of high unburned carbon fly ashes

Previous studies on carbon gasification have not included high unburned carbon content fly ashes, and therefore it remains unclear why not all fly ash carbon samples are equally suitable for activation. The concentration of active sites is well known to influence carbon gasification reactions. Therefore, the objective of this work was to investigate the effect of the concentration of active sites on the behavior of fly ash carbon samples upon steam activation. Six fly ash carbons were selected to produce activated carbons using steam at 850 °C. The concentration of active sites was determined by non-dispersive infrared analysis (NDIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). XRD analyses were also conducted to determine the crystallite size. It was observed that the concentration of active sites played a more significant effect on the surface areas of activated carbons in the carbon burn-off zone of >60%. Statistical analysis was used to relate the surface areas of activated carbon variances with carbon burn-off levels.     

Coniferous Wood Sawdust-based Activated Carbons as Adsorbents Obtained with the Use of Microwave Radiation

Activated carbons were prepared by physical and direct activation of sawdust pellets coming from coniferous trees, with the use of microwave radiation. The activated carbons obtained were used as adsorbents for the removal of methylene blue (MB) from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of each activated carbon sample was determined. The effects of activation procedure as well as adsorption tests parameters i.e., temperature, pH, initial methylene blue concentration, and contact time on the sorption capacity of each activated carbon were investigated. The kinetic models for MB adsorption on the activated carbons were also studied. Better fit to the experimental data was obtained with the Langmuir isotherm than Freundlich one, for all samples.     

Conversion of polyacrylonitrile fibers to activated carbon fibers: Effect of activation

Polyacrylonitrile (PAN)-based activated carbon fibers were developed with the idea of increasing their potential and efficiency in industrial applications. The PAN-based fibers were first oxidized in air in a continuous multistage stabilization process, and then subjected to a continuous, low temperature carbonization and activation treatment in a mixture of steam and argon. The effect of the activation condition on the specific surface area, elemental composition, as well as the morphological structure of activated carbon fibers was studied. The surface area of the carbon fibers increased remarkably after the steam activation. It was found that steam activation promoted the elimination of nitrogen from the fiber. The bulk oxygen content of the fibers increased upon activation, probably due to formation of carbon-oxygen functionalities on the surface of the activated carbon fibers. The surface oxygen level of activated carbon fibers was greater than the bulk analysis of oxygen. It was observed that activation decayed the order of the carbon structure. © 1996 John Wiley & Sons, Inc.     

2~5 nm孔集中分布泥炭基中孔活性炭的制备

将泥炭破碎、粉磨、浸渍磷酸后,压块成型、再破碎,置于管式炉经不同活化温度、活化时间制得活性炭。对浸渍磷酸后的泥炭样品在氮气下进行热重分析;测定活性炭样品的碘吸附值、亚甲蓝吸附值和焦糖脱色率,利用气体吸附仪、激光拉曼光谱、傅里叶变换红外光谱和扫描电子显微镜分别表征其孔结构、碳结构、表面化学和微观形貌。结果表明：泥炭在磷酸活化过程中发生了交联反应,炭化/活化最大失重温度从300℃附近降低至200℃附近;随着磷酸浸渍比和活化温度的升高,活性炭中的无规则石墨层增多、羟基含量减少;磷酸浸渍比增加时,孔隙逐渐发达、吸附性能增强、2~5 nm孔段孔容增大;活化温度升高时,孔隙先收缩(400~550℃)后发生破坏(600℃)、吸附性能下降、2~5 nm孔段孔容减小;随着活化时间延长,活性炭的羟基含量先大幅减小(120~150 min)后无规律变化,孔隙先扩大(120~180 min)后收缩(>180 min),吸附性能>180 min后迅速下降,碳结构和2~5 nm孔段孔容无显著变化。在磷酸浸渍比1.5、活化温度500℃、活化时间180 min条件下,制得活性炭的比表面积为678.52m²·g^-1,2~5 nm孔段的孔容达0.1475 cm³·g^-1、占总孔容比率为31.04%、占中孔容比率为70.24%。     

石油焦基高比表面积活性炭电吸附脱盐性能的研究

采用石油焦为原料,以KOH为活化剂,制得高比表面积活性炭,比表面和孔容远高于常规活性炭,孔径分布和常规活性炭相似.以高比表面积活性炭作为电吸附电极,考察其在NaCl溶液中的电吸附性能,并对话性炭电极电吸附的影响因素进行研究.结果表明,活性炭电极的电吸附性能主要受比表面积和孔容的影响,高比表面积和大孔容的活性炭单位电吸附...     

环糊精基活性炭的制备及其电化学性能

以环糊精为原料,采取先炭化后活化的方式,制备了具有高比表面积和丰富孔道结构的活性炭材料。本文通过改变KOH与环糊精炭化样品之间的碱炭比,研究了KOH用量对环糊精基活性炭结构及其电化学性能影响。在活化时间、活化温度等因素不变的情况下,活性炭的比表面积、总孔容及比电容随着碱炭比的提高,均呈现先增大后减小的趋势。当碱炭比为3时,活性炭的比表面积为1672m²/g,总孔容为0.75cm³/g,具有最佳的电容性能,在1A/g电流密度下比电容可达165F/g,优于同等条件下的商业炭21KSN（145F/g）,50000次循环后的比电容保持率为98.7%。     

Vanadium(V) Removal by Adsorption onto Activated Carbon Derived from Starch Industry Waste Sludge

This study examines the adsorption potential of activated carbons for vanadium (V) removal from aqueous solution. Activated carbons were produced via chemical activation of waste treatment sludge from the starch industry. Specific surface area and pore sizes of waste sludge samples were determined through chemical activation and pyrolysis. Experimental data indicated that sludge samples had micropore structure and specific surface area of up to 1196 m²/g. First-order and second-order models were applied to determine adsorption kinetics. Freundlich, Langmuir, and Dubinin–Radushkevich isotherms were used to analyze equilibrium data of adsorption. Equilibrium adsorption data showed the best fit to the Freundlich isotherm. Adsorption of vanadium (V) follows second-order kinetic models. Maximum adsorption was observed at pH 4.0. Langmuir adsorption capacity was found to be 37.17 mg/g. The results of the study indicated that activated carbon obtained from industrial sewage sludge was effective in removing vanadium from aqueous solutions, which creates a significant advantage for treatment of industrial wastewaters and management of solid wastes.     

苯在改性活性炭上的脱附活化能

采用浸渍法制备了KH560/改性活性炭、1706/改性活性炭和A172/改性活性炭等3种活性炭,并利用程序升温脱附技术测定了苯在这3种改性活性炭上的脱附活化能. 结果表明,苯在经改性的活性炭上的脱附活化能均大于其在未改性活性炭上的脱附活化能,表明用有机硅烷改性活性炭可以提高其对苯的吸附能力. IGC分析结果表明,经硅烷改性的活性炭的特殊作用吸附自由能DGs均小于原始活性炭的DGs,这4种活性炭表面与苯的特殊作用吸附自由能DGs大小顺序与苯在这些活性炭上的脱附活化能大小顺序正好相反,这表明DGs越小,吸附质与活性炭表面形成的吸附越牢固,吸附质从其表面脱附所需的活化能越大.     

Effect of demineralization and heating rate on the pyrolysis kinetics of Jordanian oil shales

The effect of mineral matter content on the activation energy of oil shale pyrolysis has been studied. Kerogen was isolated from raw oil shale by sequential HCl and HCl/HF digestion. Oil shale and kerogen samples were pyrolyzed in a Thermogravimetric Analyzer at different heating rates (1, 3, 5, 10, 30, and 50 °C/min) up to a temperature of 1000 °C. Total mass loss of all oil shale samples remained almost constant irrespective of the heating rate employed, whereas it decreased with the increase of heating rate for kerogen (74.5 to 71.4%). From the pyrolysis profile activation energy (Ea) was found to vary between 70 and 83 kJ/mol for oil shale, while 82-112 kJ/mol has been determined for isolated kerogen. An increase of both Ea and pre-exponential factor was observed with an increasing heating rate. It is concluded that the mineral matter in oil shale enhances catalytic cracking as is evident from the reduced Ea values of oil shale compared with those for kerogen.