Process for biphenyl purification by rectification-emulsification crystallization method

A crystallization method and process technology, applied in crystallization purification/separation, distillation purification/separation, organic chemistry, etc., can solve problems such as high solvent recovery cost, unsatisfactory crystallization effect, complex production process, etc., to reduce process complexity, Large operating flexibility, convenient and simple operation

Active Publication Date: 2011-07-20
BAOWU CHARCOAL MATERIAL TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, no matter what method is used, crystallization treatment is required. The current reported method for crystallizing and purifying biphenyl usually adopts the solution crystallization method, which is difficult to effectively solve the problem of adhesion and entrainment of impurities in the crystal, and The amount of solvent used is large and often has high toxicity, which not only leads to low yield of biphenyl, high cost of solvent recovery, but also serious environmental pollution and poor operating environment
Moreover, the conventional solvent and melt crystallization methods, because the crystallization effect is not ideal, often need to be supplemented by an extraction process, that is, three steps of rectification, liquid-liquid extraction and crystallization to complete the extraction of biphenyl, the production process is more complicated, the cost is higher, and Added solvent recovery issues
[0003] In order to solve the problems of high production cost, low biphenyl yield and serious environmental pollution in the existing refining process, the present inventor developed a method for separating and purifying biphenyl by rectification-emulsification crystallization, thus completing the present invention

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The top pressure of the rectification tower is controlled to be 50Kpa, the number of theoretical plates is 40, and the reflux ratio is 8 to carry out rectification and enrichment of biphenyl fractions to obtain biphenyl fractions with a content of 42.5%. Take 20 grams of the raw material with a biphenyl content of 42.5% and add it to 100 grams of 0.4% sodium dodecylbenzenesulfonate emulsion, gradually heat up to 85 ° C, and fully emulsify. °C, and the cooling rate is 20 °C / hour. It was then filtered, washed and dried to obtain 7.5 g of solid with a purity of 99.3% and a yield of 87.6%.

Embodiment 2

[0027] The pressure at the top of the rectification tower is 40Kpa, the number of theoretical plates is 40, and the reflux ratio is 10 to carry out rectification and enrichment of biphenyl fractions, and obtain biphenyl fractions with a content of 51.3%. 20 grams of the stock with a biphenyl content of 51.3% was added to 100 grams of a 0.3% polyoxyethylene sorbitan monostearate (Tween 60) emulsion. Then, the temperature was gradually raised to 80°C, and fully emulsified. After emulsification for a certain period of time, the mixed solution was cooled to normal temperature, and the cooling rate was 30°C / hour, then filtered, washed and dried to obtain 8.5 g of solid with a purity of 99.2% and a yield of 82.2%. .

Embodiment 3

[0029] The pressure at the top of the rectification tower is 30Kpa, the number of theoretical plates is 40, and the reflux ratio is 12 to carry out rectification and enrichment of biphenyl fractions, and obtain biphenyl fractions with a content of 75.1%. 15 grams of the raw material with a biphenyl content of 75.1% was added to 100 grams of a 0.2% polyoxyethylene nonylphenol ether (OP-7) emulsion. Then, the temperature was gradually raised to 90°C, and fully emulsified. After emulsification for a certain period of time, the mixed solution was cooled to normal temperature, and the cooling rate was 10°C / hour, and then filtered, washed and dried to obtain 10.6 g of solid with a purity of 99.7% and a yield of 93.8 %.

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Abstract

The present invention relates to a technology for purifying biphenyl by means of distillation-emulsion crystallization comprising: (1) distillation pretreatment: the solution containing rich biphenyl is get by distilling the raw material in a distillation device with a theoretical plate number of 30-60 and a column pressure of 20-60KPa; (2) emulsion and crystallization: emulsifying the rich biphenyl solution with water (the weight ratio of biphenyl solution and water is between 1:20 and 1:4) and 0.02-4wt% of emulsifier in an emulsator for 10-90 minutes at 60-100 DEG C with an emulsion pH value of 4-12, then cooling the emulsion to 5-20 DEG C; (3) separation and drying: preparing the biphenyl products after separation, washing and drying. The technology of the invention has advantages of strong adaptability to raw materials, convenient operation, simple device, mild technology condition and high product purity. At the same time the costs of material and energy consumption are greatly reduced by using water as solvent with little dosage of emulsifier and auxiliary agent, which is also useful for environmental protection.

Description

technical field [0001] The invention belongs to the field of coal fine chemical industry, and relates to a method for purifying biphenyl, in particular to a method for extracting high-purity biphenyl from coal tar. Background technique [0002] Biphenyl is an important organic chemical raw material, and its value is constantly being discovered and utilized. Biphenyl derivatives synthesized with biphenyl molecules as the skeleton can be widely used in medicine, pesticides, polymer liquid crystals, pigments, emulsifiers, fluorescence Brighteners, fabric dyes and other fields. Natural biphenyl is mainly contained in coal tar, and its mass fraction is about 0.2-0.4%. After coal tar is processed, most of the biphenyl contained in it is enriched in the oil washing fraction, and the enriched fraction contains biphenyl. Benzene varies from 7 to 10%. At present, the methods for extracting high-purity biphenyl from coal tar at home and abroad are mainly azeotropic distillation and h...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C7/04C07C15/14C07C7/14
Inventor 汪旭夏剑忠朱春燕候文杰陈叶飞
Owner BAOWU CHARCOAL MATERIAL TECH CO LTD
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