Co‐Carbonization of Medium‐ and Low‐Temperature Coal Tar Pitch and Coal‐Based Hydrogenated Diesel Oil Prepare Mesophase Pitch for Needle Coke Precursor

Abstract

Needle coke is a type of high-quality coke with needle-like texture and layer structure. [1] Also, it presents a turbine carbon structure under the scanning electron microscope. [2,3] Needle coke was acknowledged as an exceptional raw material to obtain carbon materials, because it has low coefficient of thermal expansion (CTE), high mechanical strength, easy to graphitization, and other advantages. Therefore, it is widespread used in lithium battery anode materials, high-power, ultrahigh-power graphite electrodes, and so on. [4,5] At present, residual heavy oil, catalytic cracking slurry, and high-temperature coal tar pitch are commonly used to prepare needle coke. [6][7][8] The heavy pitch component of medium-and lowtemperature coal tar has the advantages of high aromaticity, low quinoline insoluble (QI) content, and narrower molecular weight distribution. [9] So, it is an excellent raw material for the preparation of needle coke. However, the higher heteroatom content and saturation in the raw materials lead to higher thermal reaction rate in a carbonization process, which is unfavorable to prepare needle coke and the mesophase with a wide-area streamline structure. [10,11] Because the mesophase with an orderly wide-area streamlined structure is precursor for the production of high-performance green needle coke during the coke is pulled by the airflow. [12] The appropriate pretreatment methods are used to reduce the thermal reactivity of raw materials, which is essential for preparing mesophase pitch. Garcia et al. [11] reported that the

Correlation of Mesophase Properties with Molecular Structures of Pitches from Different Sources

“…It has further been shown that the alkyl side chains seriously affect the laminar orientation of mesophase molecules. 18,19 The disordered cross-linking between large radicals forms poorly planar macromolecules, reducing the lamellar orientation and graphitization ability of the carbonaceous mesophase, and eventually destroying the ordered microstructure of carbon materials. 6,20−22 Due to the influence of the process parameters, the properties of industrial pitches as a raw material for mesophase pitch are unstable, and the technology in China for the stable and continuous production of highquality mesophase pitch from different industrial pitches has not yet been realized.…”

“…It has further been shown that the alkyl side chains seriously affect the laminar orientation of mesophase molecules. , The disordered cross-linking between large radicals forms poorly planar macromolecules, reducing the lamellar orientation and graphitization ability of the carbonaceous mesophase, and eventually destroying the ordered microstructure of carbon materials. ,− Due to the influence of the process parameters, the properties of industrial pitches as a raw material for mesophase pitch are unstable, and the technology in China for the stable and continuous production of high-quality mesophase pitch from different industrial pitches has not yet been realized. The key point is that the influence of molecular structure characteristics on liquid-phase carbonization behavior is not clear since industrial pitch is a complex mixture of molecules with different structures and reactivities. − Therefore, exploring the correlation between mesophase properties and raw materials at the molecular level is essential to providing directions for the modification and preparation of mesophase from industrial pitch. , …”

Evolution of the Composition and Melting Behavior of Spinnable Pitch during Incubation

“…As the by-product of coal coking, coal tar pitch is a complex mixture system composed of a variety of polycyclic aromatic hydrocarbons, which is prone to thermal condensation or crosslinking [ 1 ]. Coal tar pitch is widely selected to produce functional carbon materials due to its easy graphitization and high carbon yield [ 2 , 3 ], such as needle coke [ 4 ], graphite electrode/anode material [ 5 ], pitch-based carbon fiber [ 6 , 7 ], porous carbon, etc. As the precursor of pitch-based carbon fiber, spinnable pitch derived from coal tar pitch needs to meet the requirements of low ash content and quinoline insoluble, relatively concentrated molecular weight distribution, good rheological properties, high softening point, and wide spinning temperature range [ 8 , 9 ].…”

Separation and thermal conversion of group components from medium‐low‐temperature coal tar pitch

“…The adsorption rate of spontaneous adsorption of neutral red solution was more than 90%, and the adsorption capacity was 155.521 mg/g. Tian et al 21,22 used medium‐low‐temperature coal tar pitch as raw material, applied by four combined pretreatment methods to prepare needle coke, and found that the needle coke prepared by solvent extraction and catalytic hydrogenation pretreatment had good fibrous structure. In addition, the refined medium‐low‐temperature coal tar pitch and coal‐based hydrogenated diesel oil can be cocarbonized to prepare mesophase pitch with sufficient light components and better order degree and can be also used to produce needle coke with high content of fibrous structure and high degree of orientation.…”