高比表面积活性炭的制备及其储氢性能的研究进展

简要分析各种储氢材料和技术的基础上,重点介绍了高比表面积活性炭的制备方法,目前最常用的活化方法是以氢氧化钾为活化剂的化学活化法;并总结了近年来前人在高比表面积活性炭储氢方面的研究结果,同时简要分析了高比表面积活性炭储氢机理方面的研究进展.     

添加聚乙二醇对酚醛树脂基球形活性炭结构和性能的影响

在以线型树脂为原料制备球形活性炭的过程中存在炭难以活化以及所制备活性炭比表积小的问题,本工作对针对此问题,提出了在线型酚醛树脂中添加聚乙二醇作为造孔剂的新方法来制备球形活性炭。结果表明：在线型酚醛树脂中添加17．6％的聚乙二醇中所制备的球形炭具有良好的活性特性;深度活化的球形活性炭球表炭球形完整,结构均匀,与未添加造孔剂的试样相比,该球形活性炭具有比表面积大,中孔率较大以及对肌酐的平衡吸附量大的特点。     

酚醛基活性炭纤维孔结构及其电化学性能研究

利用水蒸汽活化法制备了酚醛基活性炭纤维(ACF-H2O), 对其比表面积、孔结构与在LiClO4/PC(聚碳酸丙烯酯)有机电解液中的电容性能之间的关系进行了探讨. 用N2(77 K)吸附法测定活性炭纤维的孔结构和比表面积, 用恒流充放电法和交流阻抗技术测量双电层电容器(EDLC)的电容量及内部阻抗. 研究表明, 在LiClO4/PC有机电解液中, ACF-H2O电极的可用孔径(d)应在0.7 nm以上. 随着活化时间的延长, ACF-H2O的孔容和比表面不断增大, 但微孔(0.7 nm ＜ d ＜ 2.0 nm)和中孔(d ＞ 2.0 nm)率变化很小, 活化过程中孔的延伸和拓宽同步进行, 但过度活化则造成孔壁塌陷, 孔容和比表面迅速下降. 因此, 除活化过度的样品外, 电容量随比表面积呈线性增长, 最高达到109. 6 F•g-1. 但中孔和微孔的孔表面对电容的贡献不同, 其单位面积电容分别为8.44 μF•cm-2和4.29 μF•cm-2, 中孔具有更高的表面利用率. ACF-H2O电极的电容量、阻抗特性和孔结构密切相关. 随着孔径的增大, 时间常数减小, 电解液离子更易于向孔内快速迁移, 阻抗降低, 电极具有更好的充放电倍率特性. 因此, 提高孔径和比表面积, 减少超微孔(d ＜ 0.7 nm), 是提高 EDLC能量密度和功率密度的重要途径. 然而仅采用水蒸汽活化, 只能在小中孔以下的孔径范围内进行调孔, ACF-H2O电极电容性能的提高受限.     

镁基储氢合金的表面处理和表面催化

表面处理作为储氢合金性能改善的有效手段，近年来得到了很好的发展和应用，本文简要介绍了镁基储氢合金表面处理的主要方法及其对合金性能的影响。     

炭化温度对烟杆基活性炭孔结构及电化学性能的影响研究

以烟杆为原料, 氢氧化钾为活化剂, 通过调节炭化温度(500～800 ℃温度范围)在相同活化条件下制备了具有不同孔隙结构的活性炭材料. N₂吸附测试表明随着炭化温度降低, 活性炭的比表面积和总孔容先增大后减小, 中孔比表面积和平均孔径却一直增大. 其中600 ℃炭化样品经KOH活化后可制得比表面积为3333 m²•g^－1, 总孔容为2.47 cm³• g^－1, 中孔孔容达2.11 cm³•g^－1的高中孔率高比表面积活性炭材料. 采用直流充放电法、交流阻抗法和循环伏安法测定上述多孔炭为电极材料的双电层电容器的电化学性能, 结果表明: 炭化温度不同的烟杆基活性炭电极均表现出良好的功率特性, 充放电流增大50倍, 容量保持率均在80%左右, 其中TS-AC-600活性炭电极在有机电解液中1 mA•cm^－2充放电时, 比电容达到190 F•g^－1. 较高的中孔率和较大的平均孔径使得烟杆基活性炭电极具有良好的高倍率充放电性能.     

活性炭纤维孔结构控制和表面改性

活性炭纤维（ACF-ActivatedCarbonFiber）是本世纪七十年代发展起来的纤维状吸附剂[1]。其吸附性能与表面积、细孔直径、细孔分布等物理结构密切相关，同时与其表面化学结构密不可分，本文综述介绍ACF的孔结构控制方法和表面化学改性与吸附性能的关系。     

几种植物基活性炭材料的表面结构与吸附性能比较——(II)表面化学结构与吸附性能研究

用X-射线光电子能谱对3种植物基活性炭材料:椰壳活性炭 (CAC4)、剑麻茎基活性炭(SSAC)和剑麻基活性碳纤维 (SACF) 的表面化学结构进行了表征,并研究和对比了它们的吸附性能,包括对碘、苯酚和亚甲基蓝的液相吸附性能,对有机蒸汽的吸附性能以及对Au3+的还原吸附性能等。结果表明,3个样品表面均含有多种含氧官能团,吸附能力SACF>SSAC> CAC4。样品的吸附性能主要取决于自身孔结构,与其表面化学结构也有密切的关系。     

炭化对沥青基活性炭纤维的结构和超级电容器性能影响

以450℃低温炭化的各向异性中间相沥青基炭纤维为原料,先通过KOH化学活化方法制备出活性炭纤维(ACFs),再对ACFs进行炭化改性,以提高ACFs的导电率,系统地研究了炭化温度对ACFs微观形貌、结晶度、孔结构和超级电容器性能的影响。结果显示:经过1 200℃炭化处理的ACFs(ACFs~(-1)200)电极具有优异的电化学性能,在0.1 A·g~(-1)电流密度下比容量高达204 F·g~(-1),1 000次循环后电容保持率达到97.0%;且电流增至20 A·g~(-1)时依然具有高比容量(149 F·g~(-1)),表明ACFs~(-1)200电极相比于未炭化的ACFs,其导电率、大电流密度下的比容量、循环保持率均显著提高。     

Mg基非晶合金及La-Mg-Ni基复合物储氢电极的结构与电化学性能

Mg50Ni50非晶合金具有较高的初始放电容量（500mAh／g），有希望成为Ni-MH二次电池的负极合金材料。但较差的循环稳定性限制了它的进一步开发和应用。为此，本研究采用机械合金化方法，基于Mg侧进行元素替代，获得了四元Mg0.9-xTi0.1PdxNi（X=0．04-0．1）储氢合金。XRD和TEM分别从宏观和微观角度证实该系列合金仍为非晶态合金。本研究还发现，随着Pd含量的增加，腐蚀电流降低；合金的抗腐蚀能力提高。当Pd含量达到0．1的时候，Mg0.8Ti0．1Pd0．1Ni合金的耐蚀能力达到最大，其容量保持率也达到最高，经80次循环后放电容量仍然保持在200mAh／g以上。 AB3型La-Mg-Ni储氢合金与Mg基合金类似之处在于：具有较高的初始放电容量但循环容量保持率较低。为此，本研究将AB3型La0.7Mg0.3Ni3.5合金与具有较高循环稳定性的AB2型Ti0.17Zr0．08V0.35Cr0．1Ni0．3合金相复合，获得新型AB3-AB2复相合金。XRD研究表明复合物中La0．7Mg0．3Ni3．5和Ti0.17Zr0.08V0．35Cr0．1Ni0．3仍旧保持原有结构。扫描电镜（SEM）研究发现，复合物颗粒的平均尺寸在50μm左右。由于Ti0．17Zr0．08V0.35Cr0．1Ni0．3相的防护，复合物的耐腐蚀能力及100次循环容量保持率（62．3％）得以显著提高。     

几种植物基活性炭材料的表面结构与吸附性能比较-(Ⅱ)表面化学结构与吸附性能研究

用X-射线光电子能谱对3种植物基活性炭材料椰壳活性炭(CAC4)、剑麻茎基活性炭(SSAC)和剑麻基活性碳纤维(SACF)的表面化学结构进行了表征,并研究和对比了它们的吸附性能,包括对碘、苯酚和亚甲基蓝的液相吸附性能,对有机蒸汽的吸附性能以及对Au3+的还原吸附性能等.结果表明,3个样品表面均含有多种含氧官能团,吸附能力SACF＞SSAC＞CAC4.样品的吸附性能主要取决于自身孔结构,与其表面化学结构也有密切的关系.     

脱硫化氢活性炭的再生方法研究

采用了溶剂再生法和气体再生法对脱硫化氢失活后的活性炭进行再生,溶剂再生时所用的溶剂为H2O2溶液、HNO3溶液以及NaOH溶液。结果表明,NaOH溶液不能使活性炭得到再生,而H2O2溶液、HNO3溶液能够通过氧化的方法使活性炭得到再生。气体再生时所用的气体分别为高纯N2,含20%O2的N2,H2,它们再生的原理分别是热再生,通过氧化单质硫再生和通过还原单质硫再生。再生效果最好的是30%的HNO3溶液和H2,它们能将活性炭孔道内的单质硫分别脱出69.8%和81.2%,再生后的活性炭中硫容量能达到原来的70%以上。再生后活性炭的比表面积和pH值是再生性能的两个重要指标。     

Study of Water Adsorption on Activated Carbons with Different Degrees of Surface Oxidation

A carbon of wood origin was oxidized with different oxidizing agents (nitric acid, hydrogen peroxide, and ammonium persulfate). The microstructural properties of the starting material and the oxidized samples were characterized using sorption of nitrogen. The surface acidity was determined using Boehm titration and potentiometric titration. The changes in the surface chemistry were also studied by diffuse reflectance FTIR. Water adsorption isotherms were measured at three different temperatures close to ambient (relative pressure from 0.001 to 0.3). From the isotherms the heats of adsorption were calculated using a virial equation. The results indicated that the isosteric heats of water adsorption are affected by the surface heterogeneity only at low surface coverage. In all cases the limiting heat of adsorption was equal to the heat of water condensation (45 kJ/mol).     

Role of Microporosity of Activated Carbons on Their Adsorption Abilities for Phenols and Dyes

The amounts of adsorption of two commercial dyes, phenol, and 4-chlorophenol from water on activated carbons were measured at 30°C. The carbons were prepared from cane (bagasse) piths and were activated by steam. The activation temperature and time were in the ranges of 750–840°C and 2 h, respectively. It was shown that the isotherm data of all four solutes could be well fitted by the Langmuir equation under the conditions studied. The adsorption capacities of the solutes were correlated with the microporosity properties of the activated carbons including micropore volume and external surface area. Finally, the adsorption characteristics of the present carbons was compared with those prepared from various agricultural wastes.     

Chemical Modification of Activated Carbons

Mesoporous activated carbons and silica gel (Kieselgel 100, Merck) were modified as follows: (i) treatment with vinyltrimethoxysilane; or (ii)chlorination with CCl₄ followed by the reaction with a Grignard reagent. Modification of silica gel was proved by methods FTIR, NMR-¹³C and element analysis on carbon. The chemical modification of coals by alkans and olefins was supported by comparison of results of thermogravimetry for modified coals and modified silica gels. Polymerization of vinyl groups on carbon surface is shown by methods thermogravimetric analysis and differential scanning calorimetry. This revised version was published online in August 2006 with corrections to the Cover Date.     

超级活性炭的合成及活化反应机理

以石油焦为原料,采用碱熔活化法合成出具有超高比表面的超级活性炭.借助XRD、TG DTA、N2吸附实验等手段,对其结构与性能进行了表征.同时,设计原位TG DTA测试技术、反应快速终止技术,对超级活性炭合成机理进行了考察,提出了两段活化反应机理,即中温径向活化机理和高温横向活化机理.发现K2O、－O－K＋以及－CO－2K＋是径向活化为主的中温活化段的活化剂活性组分,而处于熔融状态的K＋O－、K＋则是横向活化为主的高温活化段的催化活性组分.并发现径向活化是超级活性炭形成发达微孔分布的主要途径,也是控制超级活性炭微孔分布的主要手段.而高温横向活化机理则是导致超级活性炭形成大孔的主要途径.高温横向活化与中温径向活化一起构成石油焦基超级活性炭形成的主要机理.     

Determination of the Porous Structure of Activated Carbons Using the IAE Concept. Influence of the Local Adsorption Model

In this paper we study a method for the determination of the micropore volume distribution function of activated carbons. This method is based on the Integral Adsorption Equation concept (IAE). The micropore volume distribution function is assumed to be a Gaussian of which the parameters are unknown. These parameters are determined using adsorption isotherms of carbon dioxide on a given activated carbon (F30/470 CHEMVIRON CARBON) at 278, 288, 298, 303, 308, 318 and 328 K and for pressures up to 100 kPa. Several local adsorption models are used (Langmuir, Volmer, Fowler-Guggenheim, Hill-de Boer). The influence of the choice of the local model on the pore volume distribution function is discussed. The physical validity of this function and the performances of the different models are presented. It appears that the effect of the temperature on the adsorption isotherms is difficult to model over a wide range of relative pressure. The Hill-de Boer and the Langmuir local models are the most efficient (average errors respectively equal to 3.53% and 2.80% in the studied range of temperature and pressure). They provide the most meaningful parameters for the pore volume distribution function.     

活性炭的改性研究及对四环素的吸附

研究了改性对活性炭的物理化学性质及其对四环素吸附性能的影响。结果发现,硝酸氧化改性可增加活性炭表面的酸性基团,提高比表面亲水性,降低pHPZC值,同时也改变了活性炭的表面微观形貌。低温、低浓度硝酸氧化改性,增加了活性炭的比表面积,对四环素的吸附以物理吸附为主。高温氧化改性使得比表面积降低,酸性基团增加,且吸附容量与活性炭比表面积、表面总酸度呈一定的线性关系。     

A Study on Pre-Oxidation of Petroleum Pitch-Based Activated Carbons for Electric Double-Layer Capacitors

Electric double-layer capacitors (EDLCs) are an excellent electrochemical energy storage system (ESS) because of their superior power density, faster charge–discharge ability, and longer cycle life compared to those of other EES systems. Activated carbons (ACs) have been mainly used as the electrode materials for EDLCs because of their high specific surface area, superior chemical stability, and low cost. Petroleum pitch (PP) is a graphitizable carbon that is a promising precursor for ACs because of its high carbon content, which is obtained as an abundant by-product during the distillation of petroleum. However, the processibility of PP is poor because of its stable structure. In this study, pre-oxidized PP-derived AC (OPP-AC) was prepared to investigate the effects of pre-oxidation on the electrochemical behaviors of PP. The specific surface area and pore size distribution of OPP-AC were lower and narrower, respectively, compared to the textural properties of untreated PP-derived AC (PP-AC). On the other hand, the specific capacitance of OPP-AC was 25% higher than that of PP-AC. These results revealed that pre-oxidation of PP induces a highly developed micropore structure of ACs, resulting in improved electrochemical performance.     

Adsorption of Pentafluorophenol onto Powdered,Granular, and Cloth Activated Carbons

In the present study, the adsorption of pentafluorophenol from aqueous solution onto granular activated carbon, powdered activated carbon, and activated carbon cloth has been investigated from the equilibrium and kinetic points of view. To the best of our knowledge, the removal of pentafluorophenol from aqueous solution onto activated carbon have not been reported in the literature. The experimental equilibrium data, suitably fitted by the Toth, Langmuir-Freundlich, and Redlich-Peterson isotherms, have shown that the cloth and powdered carbons exhibit the highest adsorption capacity. For all the investigated samples, the experimental kinetic data have been satisfactorily interpreted by a pseudo-second-order model. From the fitting results it has been observed that the highest rate constant and initial rate of adsorption is shown by powdered activated carbon.     

多孔炭的纳米结构及其解析

多孔炭是由超微粒子、表面、不规则结构以及纳米空间组成的混合体系, 其孔径范围以及超微粒子均在纳米尺度, 故而纳米结构包含两方面的内容: 纳米空间和纳米级粒子。对以上内容的研究和内在机理的阐明都是当今吸附领域研究的热点。本文就以上诸方面作一综述, 由此可能对深入理解吸附分离过程、阐明吸附模式、吸附机理等有一定的帮助。