The present invention relates to a process for preparing a preproduct for producing benzene from crude benzene in a coking plant, wherein the process is carried out in the evaporation step (1) of the flash tower (2). Forming coke residue while evaporating through; The crude benzene of the evaporated coking plant is converted to a preproduct using hydrogen in a pressure purifying stage (3) after the evaporation stage (3), wherein the coke residue is extracted from the evaporation stage (1) and distilled. Separating the low boiling point component and the high boiling point component in (4); High boiling point components are extracted from the exhaust stream. The flow rate of the extracted coke residue is 6% to 40% of the flow rate of the crude benzene in the coking plant, depending on the concentration of the polymer formation contained in the benzene as a raw material of the coking plant. The low boiling point component of the coke residue is extracted from the condensation step 4, condensed and fed to the flash tower 2 as reflux. The two parameters, gas pressure / temperature, are determined in principle to contain no aromatic hydrocarbons below C 9 during the distillation stage (4).
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