基于物理吸附的炭基储氢材料研究进展

开发安全、高效、经济的储氢技术是氢能产业发展的关键因素。介绍了现有的储氢技术及其特点，重点分析和综述了几种基于物理吸附的炭基储氢材料的性能特点和研究进展，包括活性炭、活性碳纤维、碳纳米纤维、碳纳米管和碳气凝胶，总结并展望了基于物理吸附的炭基储氢材料的发展趋势。     

中空活性碳纤维概述

中空活性碳纤维以其独特的结构而具有比活性炭和活性碳纤维更优异的性能，本文概述了中空活性碳纤维的制备过程及其应用，并指出，其作为吸附储氢材料具有一定前景。     

碳基储氢材料的技术研究及展望

本文从功能性材料和纤维缠绕结构性复合材料两个方面,总结了碳基材料在储氢领域的技术进展。功能型储氢材料的技术原理是表面吸附,包括活性炭、活性炭纤维、纳米碳纤维、碳纳米管、石墨烯等,应用的关键在于开发较高温度下的低成本吸附材料。高性能纤维缠绕复合材料是高压储氢技术的研究热点,结合低温技术,可以实现在保证储氢能力的同时降低压力,具有较好的经济性。     

碳材料在钴催化剂活化过硫酸盐中的研究进展

碳材料具有独特的纳米结构、优异的导电性、化学稳定性和吸附性能,是纳米金属粒子的良好载体,在催化领域具有广泛的应用前景。近年来,国内外各种碳材料在活性过硫酸盐高级氧化技术中的应用研究发展迅速。综述了各种碳材料（碳纳米管、石墨烯、碳气凝胶、碳纤维、介孔碳、活性炭和生物炭）作为钴金属及其氧化物的载体活化过硫酸盐的理论和应用研究进展,旨在为碳材料在高级氧化技术中的进一步应用提供参考。     

活性碳纤维的结构性能与应用

本文概述了近年来新开发的高效吸附材料－活性碳纤维的结构特性及吸附性能，并与颗粒活性炭进行了比较，较详细地介绍了ＡＣＦ在环保、医学等领域的应用情况。     

物理吸附储氢材料的研究进展

本文对物理吸附材料主要包括碳基储氢材料及其衍生物、沸石(分子筛)、金属有机物骨架、共价有机物骨架等进行了综述,这类材料具有高比表面积、低温储氢性能好等特点;但常温或高温储氢性能差的特点也制约了物理吸附的发展.本文最后对新型储氢材料研究进行了展望,重点在于高可逆性、高容量、高效催化加氢、常温常压下储存与运输、温和条件下可控催化脱氢等性能的研究.     

碳微晶结构对球磨制备镁基储氢材料的影响

以杏壳活性炭和煤基碳作为镁粉的助磨剂,用氢气反应球磨法制备了镁基储氢材料,对比研究了这两种不同微晶结构的碳在制备镁基储氢材料时作用的差异。结果表明,杏壳活性炭和煤基碳都是镁粉的有效助磨剂,能防止镁粉发生"冷焊"及粘附现象,得到分散的纳米级镁基储氢材料。杏壳活性炭对镁粉的分散性优于煤基碳,但用煤基碳作助磨剂所制得粉体的粒度更小,储氢密度更大,放氢温度更低。     

活性碳纤维对苯胺的吸附性能研究

采用静态吸附法探究活性碳纤维对苯胺溶液的吸附能力,探讨了在不同的吸附时间、不同质量的活性碳纤维、不同初始浓度的苯胺溶液和不同p H值、盐效应、温度等条件下对吸附效率的影响,同时探讨了颗粒活性炭对苯胺溶液的吸附能力。研究结果表明,活性碳纤维对苯胺溶液具有良好的吸附效果,即使在常温下,活性碳纤维对苯胺都具有较高的吸附效率,而盐的质量分数也会提高其吸附效率,对实际应用有参考价值;相同质量的颗粒活性炭对苯胺溶液的吸附效果不及活性碳纤维。     

多种碳材料与碳酸钠复合后脱硫性能对比

碳材料本身对于H₂S的净化效果有限,通过将活性催化剂负载到活性炭上可以弥补碳材料脱除H₂S气体能力的不足。本文选用三种具有典型孔隙结构的碳材料：微孔活性碳纤维、中孔活性炭以及孔隙更大的单壁碳纳米管,等体积浸渍不同浓度的碳酸钠溶液制作负载活性材料的脱硫剂,应用固定床反应实验评价不同负载量下制得脱硫剂的脱硫性能,并对材料进行表征测试。经过对比,具有发达微孔结构的活性碳纤维材料整体上具有最佳的脱硫性能,且活性物质的负载量并不是越大越好。实验条件下,在出口逐渐检测到SO₂以及H₂S两种气体,其中SO₂气体出现较早。测定各类碳材料负载以及脱硫前后的表面pH,发现负载Na₂CO₃后材料表面pH得到大幅度提升,而脱硫后的材料表面pH均有不同程度的下降。     

活性碳纤维脱除燃煤烟气中硫碳硝的研究进展

活性碳纤维作为新型高效的吸附材料,具有广阔的应用前景。本文对近年来改性活性碳纤维在燃煤烟气脱硫、脱硝方面的研究进行了综述,介绍了活性碳纤维在脱碳与同时脱硫脱硝方面的研究现状,可以为硫碳硝共吸附与改性吸附提供参考。同时展望了活性碳纤维在燃煤烟气中硫碳硝脱除方面未来的研究方向。     

Unique hydrogen adsorption properties of graphene

Graphene showed an unusually high hydrogen storage capacity as well as a unique, slow hydrogen adsorption process compared with a variety of carbon materials (carbon nanotubes, activated carbons, mesoporous carbons, templated carbons, and metal organic frameworks). Catalytic dissociation of hydrogen on graphene is observed for the first time. The hydrogen dissociation rate on graphene is also significantly faster than the adsorption rate. This leads to the conclusion that the most active sites on graphene for hydrogen dissociation are not the only sites where the enhanced adsorption occurs. The mechanistic differences in adsorption on graphene when compared with the other carbons are further demonstrated by differences in temperature‐programed desorption results and heats of adsorption. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

STORAGE OF HYDROGEN ON CARBON MATERIALS: EXPERIMENTS AND ANALYSES

Superactivated carbon and carbon nanotubes are both considered potential hydrogen carriers. Adsorption isotherms of H₂ on activated carbon AX-21 and multi-wall carbon nanotubes were collected with a volumetric method for the temperature range of 77, 233-298 K and pressures up to 7 or 10 MPa. Based on the experimental data for 233-298 K, the limiting heats of adsorption of 7.6 and 1.8 kJ/mol were obtained for activated carbon and carbon nanotubes, respectively. The absolute adsorption was determined with a recently presented method, and the adsorption behavior of H₂ on carbon nanotubes was thus reasonably explained. A comparison was given for the storage capacities of compression alone and of filling powder or pellets of the two materials. It was concluded that adsorption of H₂ on carbon nanotubes is too weak to enhance storage, but activated carbon enhances storage capacity considerably. The weight percentage of hydrogen stored in carbon powder reaches 10.8% at 77 K and 6 MPa, including the quantity compressed in the void space, and 4.1 kg H₂ was stored in a 100-liter container filled with carbon pellets for the same condition.     

STORAGE OF HYDROGEN ON CARBON MATERIALS: EXPERIMENTS AND ANALYSES

Superactivated carbon and carbon nanotubes are both considered potential hydrogen carriers. Adsorption isotherms of H₂ on activated carbon AX-21 and multi-wall carbon nanotubes were collected with a volumetric method for the temperature range of 77, 233–298 K and pressures up to 7 or 10 MPa. Based on the experimental data for 233–298 K, the limiting heats of adsorption of 7.6 and 1.8 kJ/mol were obtained for activated carbon and carbon nanotubes, respectively. The absolute adsorption was determined with a recently presented method, and the adsorption behavior of H₂ on carbon nanotubes was thus reasonably explained. A comparison was given for the storage capacities of compression alone and of filling powder or pellets of the two materials. It was concluded that adsorption of H₂ on carbon nanotubes is too weak to enhance storage, but activated carbon enhances storage capacity considerably. The weight percentage of hydrogen stored in carbon powder reaches 10.8% at 77 K and 6 MPa, including the quantity compressed in the void space, and 4.1 kg H₂ was stored in a 100-liter container filled with carbon pellets for the same condition.     

Molecular Simulations in Activated Carbons for Carbon Monoxide Removal From Wet Mixture of Hydrogen and Carbon Monoxide

Activated carbons are porous materials with a high surface area which are widely used in gases separation and catalysis. This work focuses on the understanding of the separation characteristics of activated carbons for purifying hydrogen from the wet mixture of hydrogen and carbon monoxide (in hundreds of ppm). This study would build a basic insight of the separation mechanism of the activated carbon and determine whether activated carbons are suitable for CO removal from the mixture. Systematic Grand Canonical Monte Carlo (GCMC) simulations have been carried out to assess the adsorption properties and selectivity of the activated carbon to the gaseous mixture with different gas phase compositions, temperatures, and pressures. The calculated adsorption isotherms, both for single and multi-component gas mixture, and isosteric heats of adsorption on the activated carbon showed reasonably good agreement with the experimental data available in the literature.     

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.     

KOH-浸渍-还原法在炭纤维表面制备不同金属纳米催化剂涂层及其应用

为了催化炭纤维原位生长纳米炭纤维／纳米碳管，研究纳米炭纤维／纳米碳管在炭／炭复合材料中的应用，采用KOH-浸渍-还原法在炭纤维上制备纳米催化剂颗粒。首先用KOH处理炭纤维改变其形貌，然后将炭纤维分别在硝酸钴和硝酸镍催化剂前驱体溶液中浸渍，干燥，再用H2气还原制得催化剂颗粒，最后催化热解CO在炭纤维上原位生长纳米炭纤维／纳米碳管。结果表明：KOH处理能使炭纤维表面变得凹凸不平，有效的阻止了催化剂前驱体液体的流动，使涂层均匀；浸渍-还原法能获得粒径小、均匀、适合纳米炭纤维生长的金属颗粒；与Co纳米颗粒相比，Ni分散效果和催化效果更好。     

碳材料在电双层电容器电极应用的最新研究

电容器与二次电池相比,有着显著的优点,尤其是高功率并能提供大电流的电双层（超级）电容器正是时代所需。对目前已用做电双层电容器电极材料的活性碳纤维、纳米碳管和膨胀性石墨的研究情况分别做了论述。与膨胀性石墨相比,如何发挥活性碳纤维和碳纳米管的实际电容效率是目前研究的重点。     

Preparation of high surface area activated carbon from corn by chemical activation using potassium hydroxide

Activated carbons were prepared through chemical activation of corn cob precursor, using potassium hydroxide as the chemical agent. The effect of different parameters, such as particle size, method of mixing, chemical/corn ratio, activation time and activation temperature, on weight loss and BET surface area of the produced activated carbons were discussed. The porosity of the activated carbons was evaluated through nitrogen adsorption. The storage capacity of the activated carbon was evaluated using natural gas. Under the experimental conditions investigated, the optimal conditions for production of high surface area carbons by chemical activation were identified. The results were compared with commercial activated carbons from coal.     

An accurate volumetric differential pressure method for the determination of hydrogen storage capacity at high pressures in carbon materials

Widely different hydrogen adsorption capacities have been reported for a variety of carbon materials which have attracted attention for hydrogen storage. This has led to doubts as to the validity of some of the claims and it has been suggested that one possible reason for the disparate hydrogen sorption capacities may lie in the inaccurate measurement of the hydrogen adsorbed. The aim of the work described in this paper was to make a contribution to this debate by developing a means and method of producing repeatable, accurate measurements of hydrogen sorption capacity in carbon materials. The apparatus developed is a volumetric differential pressure set-up operating at up to 10 MPa and the method has a conservative limit of detection of 0.1 wt% and an accuracy of ±0.05 wt%, using 1.0-2.5 g samples of the carbon materials studied. These included a carbon nanofiber sample and a series of activated carbons, the latter displaying a direct correlation between the BET effective surface area and the hydrogen sorption capacity of the materials. The amount of hydrogen adsorbed was less than 1 wt% for all the carbons examined.     

Hydrogen storage on chemically activated carbons and carbon nanomaterials at high pressures

Hydrogen adsorption measurements have been carried out at different temperatures (298 K and 77 K) and high pressure on a series of chemically activated carbons with a wide range of porosities and also on other types of carbon materials, such as activated carbon fibers, carbon nanotubes and carbon nanofibers. This paper provides a useful interpretation of hydrogen adsorption data according to the porosity of the materials and to the adsorption conditions, using the fundamentals of adsorption. At 298 K, the hydrogen adsorption capacity depends on both the micropore volume and the micropore size distribution. Values of hydrogen adsorption capacities at 298 K of 1.2 wt.% and 2.7 wt.% have been obtained at 20 MPa and 50 MPa, respectively, for a chemically activated carbon. At 77 K, hydrogen adsorption depends on the surface area and the total micropore volume of the activated carbon. Hydrogen adsorption capacity of 5.6 wt.% at 4 MPa and 77 K have been reached by a chemically activated carbon. The total hydrogen storage on the best activated carbon at 298 K is 16.7 g H₂/l and 37.2 g H₂/l at 20 MPa and 50 MPa, respectively (which correspond to 3.2 wt.% and 6.8 wt.%, excluding the tank weight) and 38.8 g H₂/l at 77 K and 4 MPa (8 wt.% excluding the tank weight).