Sulfur removal in coal tar pitch by oxidation with hydrogen peroxide catalyzed by trichloroacetic acid and ultrasonic waves

A procedure for the desulfurization of coal tar pitch (CTP) by oxidation with hydrogen peroxide (H₂O₂) was developed, in which trichloroacetic acid (TCA) was used as a catalyst combined with ultrasonic waves. For comparison, the effects of H₂O₂ combined with different catalysts on sulfur removal were also investigated. The oxidative system composed of H₂O₂ and TCA is highly effective for sulfur removal from CTP. The reaction conditions such as type of solvent used, temperature, and CTP-to-TCA ratio considerably influence sulfur removal when the same oxidant is used. The desulfurization efficiency for CTP with 0.9 wt.% sulfur content reaches 91.1 wt.% at a xylene-to-CTP volume ratio of 2.5, a CTP-to-TCA mass ratio of 0.5, an ultrasonic treatment duration of 60 min, a reaction temperature of 70 °C, and with an extraction liquid containing methanol and sodium hydroxyl. The experiment confirms that the addition of surface active agent has no beneficial effect on sulfur removal.