Process for hydrofining coking crude benzene

Abstract

The invention discloses a process for hydrofining coking crude benzene, which consists of a raw-materialnits preseparating unit, a hydrofining unit, a predistillation unit, an extractive distillation, an aromatic-hydrocarbon refining unit and a xylene distillation unit, wherein supplementary hydrogen needed in reaction is supplied from the outside; a reaction part in the hydrofining unit adopts three-stage hydrogenation; and the temperature of second-stage hydrogenation and third-stage hydrogenation is 230 to 290 DEG C and 220 to 315 DEG C respectively. The process has the advantages that the temperature adopted in both the second-stage hydrogenation and the third-stage hydrogenation is greatly lower than the reaction temperature of the prior process; the process effectively reduces benzene transformed into cyclohexane, reduces the secondary cracking reaction of the cyclohexane, reduces the loss of aromatic compound, and improves the retention rate of aromatic hydrocarbon which can reach over 99.6 percent; meanwhile, the three-stage hydrogenation adopted in the reaction part prolongs the process of hydrogenation and ensures that sulfur-containing nitrogen-containing organic compounds can also be transformed into inorganic sulfur or inorganic nitrogen compounds at a lower temperature, so that the aim of purification is achieved; and the total content of both sulfur and total in a hydrofined product is less than 1 ppm.

Description

1. Technical field [0001] The invention belongs to the technical field of coal chemical industry, and in particular relates to a coking crude benzene hydrotreating process. 2. Background technology [0002] In recent years, with the continuous development of the national economy, the country's demand for coke has grown rapidly, resulting in a continuous increase in the output of coking crude benzene and other resource-based by-products. Since coking crude benzene contains some unsaturated hydrocarbons and sulfur-containing and nitrogen-containing organic compounds, such as linear alkane mercaptans, aryl mercaptans, thioethers, thiophenes, dibenzothiophenes, thioindenes, pyridines, etc., it cannot be directly used as organic Synthetic raw materials are used only after the above impurities are removed. The traditional impurity removal method for coking crude benzene is pickling, although this method can partially remove sulfur-containing compounds (mainly thiophene) and other...

AI Technical Summary

Problems solved by technology

However, the temperature required for this kind of low-temperature hydrogenation method still needs to reach 320°C to 380°C. At this temperature, benzene will be converted into cyclohexane, which is very prone to secondary cracking, and the loss of aromatic compounds is relatively large, which reduces the retention rate of aromatics.

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