Preparation And Properties Of Pitch-based Activated Carbon Fibers By Metal Catalytic Activation

Activated carbon fiber(ACF)is widely used in catalytic adsorption,battery anodes,harmful gas removal and environmental purification as a new generation of high-performance adsorption material,which possesses excellent adsorption performance,fast adsorption rate,large specific surface area,small fiber diameter and simple processing.In recent years,the functional modification and regulation of ACF(building hierarchical pore structure,loading metal nanoparticles,modifying surface functional groups)and its application in electrochemistry and volatile organic gas(VOCs)adsorption have gradually become the hotspot and focus of research.In this thesis,the spinnable pitch precursor was synthesized by the in-situ polymerization of the cheap ethylene tar as a raw material with adding the metal salt,and then the pitch-based ACF was prepared through melt spinning,stabilization,carbonization and steam activation processes.The effects of different types and contents of metal salts on the pore structure of ACF and the mechanism of metal catalytic activation were systematically studied.Meanwhile,the electrochemical performance of pitch-based ACF loading metal nanoparticles as an anode material of potassium ion battery(PIB)was explored,and the adsorption performance of pitch-based ACF with hierarchical pore structure for ethanol adsorption was inverstigate.The results showed that the metal nanoparticles played a significant role in catalytic activation for prepearing the pitch-based ACFs with a hierarchical pore structure consisting of abundant micropores and well-developed mesopores.The obtained pitch-based ACFs loading metal nanoparticles successfully solved the negative problems of low battery capacity and poor cycle kinetics of PIB caused by excessive potassium ion radius,and the pitch-based ACFs with hierarchical pore structure appeared good adsorption performance for ethanol.The specific results and conclusions are as follows:(1)The IP-4.5Ni N-ACF prepared by adding 4.5%nickel nitrate which exhibits a specific surface area of 2284 m² g^-1,a mesopore ratio of 41%,and an average pore diameter of 3.5 nm.The specific surface area of ACF increases with the percentage of metal salt which will affect the spinning performance of pitch.More importantly,adding organic metal salt is more conducive to catalytic activation than inorganic metal salt to prepare ACF with developed pore structure.(2)The pitch-based ACF(ACF/Ni S)rich in Ni S nanoparticles is prepared by the vulcanization process which is rich in suitable pore structure and high-activity nanoparticles.Resultly,the ACF/Ni S anode shows a high ICE(84.22%)and excellent potassium ion storage(292.5 m A g^-1,with the current density of 0.5 A g^-1).(3)The pitch-based ACF(H-ACF-3.0)with hierarchical pore structure is prepared by pickling process from pitch-based ACF which is rich in metal nano-particles,and H-ACF-3.0 including mesoporous structure and surface functional groups.As a VOCs adsorption material,H-ACF-3.0 exhibits a higher dynamic adsorption capacity of ethanol(1.13 mmol g^-1).In a word,the pitch-based ACF with excellent adsorption performance and abundant active sites could be prepared by the in-situ polymerization of the ethylene tar and metal salt.This paper not only reveals the mechanism of catalytic pore expansion and metal nanoparticle loading of pitch-based carbon fiber prepared by metal catalytic activation,but also provides a material with excellent performance for PIB anode and ethanol adsorption,lays a certain theoretical foundation for the design and construction of the material.