Preparation method of beta-methylnaphthalene

Abstract

The invention relates to a preparation method of beta-methylnaphthalene, which uses oil level mixed methylnaphthalene containing 50-70% of beta-methylnaphthalene as raw material, depressurizes and distills to obtain beta-methylnaphthalene product containing at least 80% of beta-methylnaphthalene, freezing and centrigually treating the beta-methylnaphthalene to obtain the beta-methylnaphthalene product. The preparation method can obtain the beta-methylnaphthalene whose purity is higher than 97%, with simple operation, low production cost and little environment pollution.

Description

technical field [0001] The invention relates to a preparation method of methylnaphthalene. Background technique [0002] At present, the method of producing β-methylnaphthalene is to use the crude methylnaphthalene in coal tar as raw material, after pickling to obtain the methylnaphthalene fraction with a content of 50% of β-methylnaphthalene, and then azeotropic distillation to produce β-methylnaphthalene -Methylnaphthalene. The biggest problem that this method brings is that the solution pollution after the initial pickling is very big, and the treatment cost is relatively expensive, and the β-methylnaphthalene content produced is not high (the β-methylnaphthalene content is greater than 95%, and the indole content is between 0.2~1%), in order to obtain high content of β-methylnaphthalene, it is necessary to deindole again, with 55~65% concentration of H 2 SO 4 Solution, according to the ratio of oleic acid to 1: 1 ~ 4: 1, carry out pickling; : 1~4: 1, carry out alkali...

AI Technical Summary

Problems solved by technology

The biggest problem that this method brings is that the solution pollution after the initial pickling is very big, and the treatment cost is relatively expensive, and the β-methylnaphthalene content produced is not high (the β-methylnaphthalene content is greater than 95%, and the indole content is between 0.2~1%), in order to obtain high content of β-methylnaphthalene, it is necessary to deindole again, with 55~65% concentration of H 2 SO 4 Solution, according to the ratio of oleic acid to 1: 1 ~ 4: 1, carry out pickling; : 1~4: 1, carry out alkali washing, finally obtain the β-methylnaphthalene of the white crystal of indole content through distillation and be less than or equal to 0.02%, although the β-methylnaphthalene purity that this kind of method obtains can reach 98%, But the cost is high, and the pollution increases after pickling and alkali washing, and the use of 55-65% sulfuric acid solution is also an important source of danger for the safety of workers