Method for extracting biphenyl from middle washing oil

Abstract

The invention discloses a method of extracting biphenyl from medium wash oil. The medium wash oil containing 15 percent of biphenyl is used as the raw material to be processed for three times of batchdistillations inside a rectifying still and a distillation column with the theoretical plate number of 50 to 80 pieces to obtain the biphenyl product, the purity of which is more than 95 percent, andat the same time, industrial methylnaphthalene, mixed dimethyl naphthalene fraction and acenaphthene fraction are obtained. The technology of the invention is simple and is easy for grasping. Under thetechnical condition that the devices for the three times distillations, the theoretical plate number of the distillation column, the pressure of the rectifying still, the reflux ration and the temper ature of the rectifying still are same, the required products can be produced just by slightly adjusting the temperature of the rectifying still and the top temperature of the distillation column. Theextraction rate of the biphenyl can be more than 70 percent. A coking plant which produces 4000t medium wash oil yearly can produce 400t biphenyl product yearly, the biphenyl content of which is more than 95 percent, and the coking plant can obtain 1000t industrial methylnaphthalene, 1300t mixed dimethyl naphthalene fraction and 1200t acenaphthene fraction at the same time, so the comprehensiveeconomic benefit is very considerable.

Description

technical field [0001] The invention belongs to the field of coal chemical industry, and in particular relates to a method for producing biphenyl by using middle-weight washing oil. Background technique [0002] The production methods of biphenyl are mainly chemical synthesis methods such as preparing biphenyl by pyrolysis of benzene and the method of separating and extracting biphenyl from coal tar fractions. At present, biphenyl in my country is produced by synthesis. The method of extracting biphenyl is still in the laboratory stage and has not been industrialized. [0003] There are two main methods for separating biphenyl from coal tar: potassium fusion method and azeotropic distillation method. [0004] Potassium melting method: rectify the washing oil, cut the fraction at 240°C to 260°C, remove indole with potassium hydroxide, separate the neutral oil as the raw material for extracting biphenyl, and then cut the fraction at 252°C to 262°C with a rectification tower. ...

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