Scheme for Hydrotreatment of Fluid Catalytic Cracking Decant Oil with Reduced Hydrogen Consumption and High Needle Coke Yield upon Carbonization

Two decant oils with different sulfur contents and their vacuum distillation fractions were hydrotreated in a fixed bed flow reactor to produce a feed with sufficiently low sulfur content for needle coke production. Products from hydrotreatment were subsequently carbonized in a tubing bomb reactor to characterize the carbonaceous mesophase development seen in the resulting semicoke. Although the purpose of the hydrotreatment is to reduce sulfur content, hydrogenation of aromatic compounds also takes place during the treatment, thus increasing the hydrogen consumption. Modest hydrogenation of decant oil from the hydrotreatment improved the mesophase development but resulted in a significant decrease of the semicoke yield upon carbonization of the treated product. As a remedy to conserve hydrogen during hydrotreatment and achieve higher coke yields in the subsequent carbonization, only the middle fraction from vacuum distillation of the decant oil was hydrotreated and blended back with the vacuum bottoms to simulate the coker feed. This scheme was successful to attain the desirable sulfur reduction in the feedstock without the penalty of a reduced coke yield upon carbonization or useless hydrogen consumption.