Needle coke is a silver-gray porous solid with obvious fiber texture direction, and has the characteristics of high crystallinity, high strength, high graphitization, low thermal expansion, low ablation, etc. It has special uses in national defense and civilian industries It is a high-quality raw material for the manufacture of graphite electrodes, battery anode materials and high-end carbon products.

According to the different production raw materials used, needle coke can be divided into two types: oil-based and coal-based: needle coke produced from petroleum refining products is called oil-based needle coke, and coal tar pitch and its fractions Needle coke produced from oil is called coal-based needle coke. The production of needle coke with petroleum products has outstanding environmental protection advantages, and the implementation is less difficult and the production cost is low, so it has been paid more and more attention by people.

Oil-based needle coke can be divided into two types: raw coke and cooked coke (calcined coke). Among them, raw coke is used to produce various battery negative electrode materials, and cooked coke is used to produce high-power graphite electrodes. In recent years, with the increasingly severe environmental protection situation, the rapid development of new energy vehicles has led to a high demand for battery anode materials; at the same time, the outdated converters of steel companies have been replaced by electric furnaces. Under the dual effects, the market demand for needle coke has increased significantly. At present, the oil-based needle coke production in the world is dominated by American companies, and only a few companies such as Jinzhou Petrochemical, Jingyang Petrochemical and Yida New Materials have achieved stable production in my country. High-end needle coke products mainly rely on imports. Not only is a lot of money wasted, but it is also easily contained. It is of great strategic significance to speed up the research on the production process of needle coke and realize the jacking up with production as soon as possible.

Raw material is the key factor affecting the quality of needle coke. Suitable raw material can greatly reduce the difficulty of forming mesophase pitch and remove subsequent unstable factors. The raw materials for producing needle coke should have the following characteristics:

①The content of aromatics is high, especially the content of 3 and 4-ring short side chain aromatics in linear arrangement is preferably 40% to 50%. In this way, during carbonization, aromatics molecules condense with each other to form larger planar aromatics molecules, and through the large π The bonded electron clouds are superimposed on each other to form a relatively complete graphite-like structure lattice

②Asphaltenes and colloids that exist in the molecular structure of fused-ring large aromatic hydrocarbons have low content. These substances have strong molecular polarity and high reactivity. , It is generally required that the heptane insoluble matter is less than 2%.

③The sulfur content is not more than 0.6%, and the nitrogen content is not more than 1%. Sulfur and nitrogen are easy to escape due to high temperature during the production of electrodes and cause gas swelling, which will cause cracks in the electrodes.

④ The ash content is less than 0.05%, and there are no mechanical impurities such as catalyst powder, which will cause the reaction to proceed too fast during carbonization, increase the difficulty of forming mesophase spheres, and affect the properties of coke.

⑤ The content of heavy metals such as vanadium and nickel is less than 100ppm, because the compounds composed of these metals have a catalytic effect, which will accelerate the nucleation of mesophase spheres, and it is difficult for the spheres to grow sufficiently. At the same time, the presence of these metal impurities in the product will also cause voids, Problems such as cracks lead to a decrease in product strength.

⑥ Quinoline insoluble matter (QI) is zero, QI will be attached around the mesophase, hindering the growth and fusion of spherical crystals, and the needle coke structure with good fiber structure cannot be obtained after coking.

⑦The density is greater than 1.0g/cm3 to ensure sufficient yield of coke.

In fact, feedstock oils that meet the above requirements are relatively rare. From the perspective of components, catalytic cracking oil slurry with high aromatic content, furfural extracted oil, and ethylene tar are ideal raw materials for needle coke production. Catalytic cracking oil slurry is one of the by-products of the catalytic unit, and it is usually shipped as cheap fuel oil. Due to the large amount of aromatic content in it, it is a high-quality raw material for the production of needle coke in terms of composition. In fact, worldwide The vast majority of needle coke products are prepared from catalytic cracking oil slurry.