Preparation of Molecular Sieving Activated Carbon Fiber from Pitch-Based Carbon Fiber

本研究以石油沥青基碳纤维为原料，采用化学气相沉积法制备孔径均匀的多孔活性碳纤维。很明显，原料碳纤维的窄直径（约16 μ m）是阻碍现有碳活化技术应用于活性炭生产的主要因素之一。具体地，我们能够表明，为了自由地控制和均匀地设计孔结构，同时满足增加表面积和保持高产率的对立要求，有必要：（1）选择具有可容易控制的氧化能力的活化气体（二氧化碳）;（2）将活化气体的氧含量降低至小于约10%。1 ppm ;（3）在活化处理过程中保持炉内温度分布均匀，研究了在预定温度（850、900、950 ℃）下，在较宽的处理时间范围内，多孔活性炭纤维的比表面积与产率之间的关系。结果表明：1）制得的活性炭具有较高的比表面积（2800 m^2/g），产率为42%; 2）制得的活性炭对甲烷、乙烯、正丁烷、异丁烷等烃类气体的气相吸附容量和吸附速率分别为1000 m^2/g和1000 m^2/g; 3）测定了该树脂对氯仿和腐殖酸的吸附容量和吸附速率。

The purpose of this work is to develop a process for the preparation of porous activated carbon fiber (ACF) with uniform pore size using petroleum-pitch-based carbon fiber as a precursor. It became clear that the narrow diameter (ca.16 mu m) of the raw material carbon fibers is one of the main factors preventing the application of existing carbon activation techniques to the production of activated carbon. In concrete, we were able to show that in order to freely control and design the pore structure uniformly whilst meeting the antagonistic requirements of both increasing the surface area and maintaining a high yield, it is necessary to : (1) select an activation gas that has an oxidizing ability which can be controlled with ease (carbon dioxide) ; (2) reduce the oxygen content of the activation gas to less than approx. 1 ppm ; (3) maintain a uniform temperature distribution in the furnace during activation treatment.The relationship between the specific surface area and the yield of porous activated carbon fiber was studied over a wide range of treatment time at predetermined temperatures (850,900,950 ﾟC). As a result, we were able to prepare a series of activated carbon samples with molecular sieving function differing from each other only in their pore size and were able to evaluate the pore structures and adsorption properties thus :1) ACF with a high surface area (2800 m^2/g) and a yield of 42% was obtained.2) Capacity and rate of gas phase adsorption of hydrocarbons (methane, ethylene, n-butane, iso-butane etc.) were measured and the character of the pore structures was investigated.3) Adsorption capacity and adsorption rate of chloroform and humic acid in aqueous phase were determined.