Study On Preparation Of Polyacrylonitrile Based Activated Carbon Fiber

Polyacrylonitrile based activated carbon fiber (PAN-ACF) is a new type of fibrous adsorption material, which has porous structure, high adsorption capacity. It not only has the characteristics of large adsorption capacity, fast adsorption speed and excellent adsorption performance, but also has the advantages of easy conduction, small thermal expansion coefficient, good corrosion resistance and excellent mechanical properties.Due to excellent physical properties, PAN-ACF has received increasing attention in numberous application,for instance, environmental protection,automotive, aerospace, biological. However, the commonly used process for the production of PAN-ACF in the industry is intermittent production,the production efficiency is low, the quality of the product is unstable,and the adsorption performance is general. In addition, the use of raw materials must first be processed into carpets or cloth, then through the activation treatment, the final product with low mechanical properties,easy to break and powdered.In this study, PAN-ACF was prepared by continuous production process of PAN precursor through continuous production line. Based on the study of the pre oxidation process, we explored the impact of/the effects of the structure of the pre oxidized fiber on the pore structure,mechanical properties and grain size of PAN-ACF. Furthemore,we also simplified the process, reduced the production time and improved the production efficiencyDifferent types of PAN-ACF were prepared by three different activation processes: water vapor physical activation, KOH chemical activation and secondary activation (prior to hydrothermal chemical activation). Through the comparison of the three different processes and the structure and performance of the final products, we can find out the products which are suitable for the industrial production and practical use.The results shown that the PAN-ACF prepared by the physical activation of water vapor has low adsorption performance (iodine adsorption value is 931mg/g, BET specific surface area is 661m2/g), and the mechanical properties are excellent (strength is 1.44GPa). The PAN-ACF prepared by chemical activation has excellent adsorption performance (iodine adsorption value is up to 1987.3mg/g and the specific surface area is up to 2549.5m2 /g), but the mechanical properties are poor (the strength is very low). The sample has a lot of broken filament and yarn break, and the surface has a large number of chemical reagents that affect its application. PAN-ACF prepared by secondary activation method has excellent adsorption performance (iodine adsorption value up to 1900mg/g, specific surface area is up to 2051.14m2/g), excellent mechanical properties (strength is 0.68Gpa). The surface of the sample is good, and the surface attached with less chemical reagent, which is suitable for industrial production and is convenient for practical use.