酚醛基活性碳纤维

酚醛树脂属于难石墨化碳，适宜制造活性碳纤维(ACF)，其特点是碳化活化收率高，制品强度高，比表面积大，孔径分布属于单峰形，吸附容量大；细孔入口形状属于狭缝形，吸脱速度快；制品柔软，深加工性好，它除用于治理环境污染外，还可用于制作防化防毒服和制造超级电容器等。     

Defluorination-enhanced hydrogen adsorptivity of activated carbon fibers

Fluorinated activated carbon fibers (F-ACFs) were prepared by direct thermal fluorination of pristine activated carbon fibers. By the pyrolysis of F-ACFs at 1073 K under nitrogen gas flow, fluorine was subsequently eliminated and the sp²-bonded ACF structures were recovered. The micropore widths were 1.1 and 0.8 nm, and the isosteric heats of adsorption of nitrogen were 11.3 and 12.8 kJ/mol for pristine and defluorinated ACFs, respectively. These results strongly suggest that changes occurred in the structural properties of micropores in defluorinated ACFs. The hydrogen adsorption isotherms showed that the defluorinated ACFs adsorbed more hydrogen gas than pristine ACFs at 77 K, suggesting that the potential for interaction between hydrogen molecules and the defluorinated slit nanospaces was increased due to the changes in the pore structural properties and/or to the induced polarization of the pore walls making up the modified π-electron systems.     

活性炭纤维用于苦卤脱色的研究

采用活性炭纤维（ACF）对海盐苦卤进行吸附脱色实验.通过动态吸附实验,探讨了活性炭用量、溶液流速、温度、浓度、pH对脱色率的影响.确定活性炭纤维对苦卤溶液脱色的最佳工艺条件为：温度20 ℃,苦卤溶液浓度（以溶液中X-计）为2 mol/L,溶液pH＝6,动态吸附流速为6 mL/min.在此条件下,苦卤脱色率大于98%.活性炭纤维对海盐苦卤的饱和吸附量比颗粒活性炭大10倍.吸附后的活性炭纤维加热到120 ℃并抽真空进行脱附,可循环使用18次以上.     

以纸巾为模板制备活性炭纤维

以纸巾为前驱体通过NaOH化学活化制备活性炭纤维,扫描电镜观测其微观结构为多孔纤维状。通过活性炭纤维对亚甲基蓝的吸附实验研究活性炭纤维吸附动力学,Pseudo-second-order方程比Pseudo-first-order方程更适于吸附数据模型,相关系数高达0.998,所制备活性炭纤维对亚甲基蓝最大平衡吸附量为200mg/g。     

Characterization of differently shaped carbon fiber composites prepared from naphtha cracking bottom oil

Different shaped carbon fibers (R-, I-, C-, Y-, and X-type) were prepared from melt-spinning of reformed naphtha cracking bottom oil precursors through various shaped spinnerets. These different shaped CFs (carbon fibers) and PVC (polyvinyl chloride) resin were compounded, and then CF/PVC composites were prepared. Precursor pitch, carbon fibers, and composites were characterized and their properties were compared. Mechanical properties of carbon fibers and composites were characterized relating to external surface area and ratio of perimeter to cross-sectional area of carbon fibers. The tensile strength of tetralobal fibers (X-type) showed five times higher than that of round-shaped fibers (R-type) due to extended external surface area. Their tensile strength of CF/PVC composite increased as ratio of perimeter to cross-sectional area of carbon fibers. The magnitude of the ratio was in order to X-, C-, I-, Y-, and R-type.     

Preparation and characterization of silicon carbide fibers from activated carbon fibers

Silicon carbide fibers were prepared by the reaction between activated carbon fibers and silicon monoxide generated from a mixture of silicon and silicon dioxide at temperatures from 1200 to 1300°C in an inert atmosphere of argon. The reaction was completed at temperatures as low as 1200°C, which means that activated carbon fibers had a high reactivity. The resulting sample maintained the original morphology of the starting material, which was an advantage because of the difficulty in post shaping silicon carbide, and led to a silicon carbide fiber with high specific surface area. The resulting samples were characterized by powder X-ray diffraction, thermal gravimetric analysis, and by nitrogen adsorption measurements at 77.4 K to obtain surface area and pore size distributions. The morphology of the resulting sample was observed by scanning electron microscopy and the electronic structure was investigated by Fourier transformation infrared spectroscopy and X-ray photoelectron spectroscopy techniques.     

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N₂ adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO₂ flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N₂ adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m²/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N₂ adsorption measurements.     

酚醛基活性炭纤维的研究进展

从酚醛树脂的合成经纺丝成纤制得酚醛纤维,再将酚醛纤维经碳化、活化最终制得酚醛基活性炭纤维(PACF)的工艺过程综述了PACF的研究进展;其中重点介绍了酚醛树脂的成纤方法:熔融纺丝法、离心纺丝法、湿法纺丝法以及酚醛纤维的化学活化法和物理活化法;阐述了PACF的结构性能以及在吸附领域、超级电容器、高效集热材料,抗菌纤维等方面的应用;展望了PACF的发展前景,指出降低生产成本,避开溶液固化过程、降低污染、拓展应用范围是PACF在未来一段时期内的研究方向。     

Oxidative dehydrogenation of ethylbenzene on activated carbon fibers

Activated carbon fibers from different precursors and with different degrees of activation were used as catalysts for the oxidative dehydrogenation of ethylbenzene. Within each group, the fibers exhibited similar surface chemistries, so that the observed catalytic performances could be interpreted exclusively in terms of their textural properties. Analysis of the catalytic results highlighted common trends. In particular, the fibers with an average micropore width larger than 1.2 nm were found to be the best catalysts for this reaction.     

Preparation of activated carbon fibers from polyvinyl chloride

Waste polyvinyl chloride (PVC) contains high content of chlorine, which is believed to liberate dioxine at its combustion. Efficient removal of chlorine from PVC achieved by selecting the heat-treatment conditions provided free-chlorine PVC based pitch by a two-stage heat-treatment process. The obtained pitch (softening point: 218 °C) was spun, stabilized, carbonized and activated to prepare activated carbon fibers (ACF) whose DeSO_x activity was tested preliminarily and found comparable to other ACF.     

Characterization of activated carbon fibers using argon adsorption

In this paper, we present results of the internal structure (pore size and pore wall thickness distributions) of a series of activated carbon fibers with different degrees of burn-off, determined from interpretation of argon adsorption data at 87 K using infinite and finite wall thickness models. The latter approach has recently been developed in our laboratory. The results show that while the low bun-off samples have nearly uniform pore size (<0.6 nm), the pore size distribution of the high burn-off samples becomes broader, with a significant increase in proportion of larger pores. The results of pore wall thickness distribution are generally consistent with development of porosity with increasing degree of burn-off. Further they show good correspondence with X-ray diffraction.     

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.     

聚丙烯腈基活性碳纤维吸附CO2的性能

以国产聚丙烯腈(PAN)基碳纤维为原料,采用KOH为活化剂制备PAN基活性碳纤维。测定了不同ACF样品的CO2吸附量,并通过氮气吸附、碘吸附以及红外光谱对所得活性碳纤维的比表面积、孔结构及表面官能团进行表征。研究了活化温度、活化时间和表面改性对活性碳纤维CO2吸附量的影响。结果表明,活化温度是影响活性碳纤维CO2吸附量的主要因素。当活化温度为850℃时,所得活性碳纤维BET比表面积为1235m2/g,微孔比表面积为745 m2/g,在吸附温度为273 K、吸附相对压力P/P0为1时,CO2的吸附量达到87.29 mL/g。     

Charge carrier transport control in activated carbon fibers

We present the results of measurements of electronic transport in an activated carbon fiber performed over a wide temperature range. The fiber had been subjected to the adsorption of various molecules, one type at a time. The presence of guest molecules inside the fiber’s pores causes significant changes in the electronic transport which has been observed to depend on the molecules’ dipole moment. Results show the possibility of controlling the charge carrier transport through the fiber by using specific adsorbents.     

Studies on the structure of activated carbon fibers activated by phosphoric acid

By solid‐state ¹³C‐ and ³¹P‐NMR, XPS, and FTIR, the chemical structure of activated carbon fiber–P (ACF‐P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen‐containing groups were greatly reduced at high activation temperatures. Different from the ACF‐W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF‐P. The original ACF‐P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF‐P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF‐P activated at lower temperature possessed a large amount of oxygen‐containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of ³¹P‐NMR, P_2p‐XPS, and FTIR at 1620 cm^?1 shifted with the increase of activated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2253–2261, 2003     

Capacitance behavior of activated carbon fibers with oxygen-plasma treatment

Modified activated carbon fibers (ACFs) were used as the electrodes of an electric double-layer capacitor and showed an enhanced capacitance effect after a RF-plasma treatment. The capacitance and the surface functional groups of the ACFs were studied. For the plasma-treated ACFs having a specific surface area of 1500 m² g⁻¹, the capacitance increased by 28% compared to the untreated sample and the highest electric capacitance value of 142 F g⁻¹ was achieved with an oxygen feed concentration of 10 vol.%. The Brunauer-Emmett-Teller (BET) surface area was 2103 m² g⁻¹, which was 34% higher than that of the untreated sample. The pore volume was similarly increased to 483.1 cm³ g⁻¹ STP, and from the pore distribution plot, quantities of mesopores of 10 nm or less and micropores also increased. However, in order to enhance the capacitance, the quinone functional group had a significant influence in addition to the BET surface area. The correlation between the capacitance and the number of quinone functional groups was confirmed because quinone is an electron acceptor.     

Preparation of mesoporous activated carbon fibers by catalytic gasification

A commercial activated carbon fiber with micropores, CH700-20 (Kuraray), was reformed to a mesoporous one by catalytic gasification. The catalytic gasification was composed of two steps: CO₂ pretreatment and air oxidation. Cobalt was used as the catalyst and gasification was performed in the temperature range of 500–700 °C. BET surface area and pore volume of catalytically modified carbon fiber were analyzed by N₂ adsorption. BET surface area of the original CH700-20 was 1,711 m²/g, and the mesopore volume percentage was 11.9%. After catalytic gasification, BET surface area was similar to the original CH700-20, while mesopore volume percentage increased up to 56%. The average pore size of mesopores was 3–4 nm in diameter. The average size of mesopores could be controlled with nanometer resolution by varying the temperature and time of activation.     

沥青基活性碳纤维动态吸附甲苯的性能

以通用级沥青基碳纤维为原料,采用钴盐催化活化法,通过改变活化剂用量和活化时间制备出不同的活性碳纤维。研究了活性碳纤维的动态吸附甲苯以及再生性能。结果表明,活性碳纤维是一种优秀的甲苯吸附材料,其饱和吸附量受比表面积和孔径及其分布的影响。活性碳纤维对甲苯的动态吸附量达到1250 mg/g。20次吸脱附循环再生后,吸附量仍保持在900 mg/g。