The desulfurization of coal tar pitch with potassium permanganate oxidation method

Needle coke is widely used as precursor of some carbon material, such as graphite electrodes or negative material for lithium-ion battery of new energy vehicle. Coal tar pitch (CTP) is its raw material. The sulfur content in the CTP has an adverse effect on the quality of needle coke. Therefore, reducing the sulfur content in CTP has important practical significance to produce high-quality needle coke. The common methods of hydrogenation or oxidation for the CTP desulfurization is not easy operation with high energy consumption. This paper innovatively proposed a new method that is easy operation with low energy consumption for desulfurization of the CTP. It is carried out under room temperature and pressure with KMnO4 as the oxidant, ferric chloride (FeCl3) as the catalyst, and methanol as an extractant. The single factor method was used to investigate the optimal condition of oxidant concentration, oxidant dosage, methanol dosage, and reaction time on the desulfurization rate (DR) of the CTP. The result showed that the DR of the CTP reached 62% at the optimal condition. The remove ratio of different forms of sulfur in the CTP was in the order of thiophene sulfur > mercaptan and thioether > sulfoxides. This method was effective and showed promising in commercial application.