Method for extracting and separating cresol from phenol-containing oil by using imidazolium-based ionic liquid

Abstract

The invention provides a method for extracting and separating cresol from phenol-containing oil by using an imidazolium-based ionic liquid. The imidazolium-based ionic liquids such as 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium methyl sulfate and 1-butyl-3-methylimidazolium dimethylphosphate have a separation effect. The technical scheme proposed by the invention is as follows: the phenol-containing oil is introduced from the bottom of an extraction tower, the ionic liquid extractant is introduced from the top of the extraction tower, and multi-stage countercurrent extraction is performed on the phenol-containing oil and the ionic liquid extractant; after extraction is completed, an oil phase is extracted out from the top of the tower, and the cresol-containing ionic liquid enters a rectification column after being decompressed, wherein the decompression operation can reduce the boiling point of the cresol, thereby reducing energy consumption; and the cresol isextracted out from the top of the rectification column, the ionic liquid is extracted out from the bottom of the rectification column, and after the pressure returns normal pressure, the ionic liquidcan be recycled to the extraction tower for reuse. The method has a simple process, the continuous operation is easy to realize, and the high-purity cresol can be obtained after treatment; and when the ionic liquid is used as the extractant, the extraction effect can be improved, and the environmental pollution caused by an organic extractant can be reduced.

Description

technical field [0001] The invention belongs to the field of chemical separation, and relates to a method for extracting and separating cresol in phenol-containing oil by using ionic liquid, in particular using ionic liquid extractant liquid-liquid extraction to separate cresol in phenol-containing oil, and then obtaining pure Cresol, method for simultaneous recovery of ionic liquids. Background technique [0002] As an important source of high value-added products, coal tar produced during coal pyrolysis has been widely used in chemical, pharmaceutical, dye, pesticide, plastic, synthetic fiber, synthetic rubber, refractory high-temperature materials, national defense industry and carbon. application, some of the polycyclic aromatic hydrocarbons cannot be replaced by the petroleum industry. The content of phenolic substances in coal tar is very high, reaching 25%-30%. Among them, cresol is an important chemical raw material with high added value. It is a valuable raw mater...

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Problems solved by technology

[0005] The patent [a method and device for separating various phenols from medium and low temperature coal tar crude phenols] uses phosphoric acid and sulfuric acid as extraction agents, which is not conducive to environmental protection

[0006] The disadvantages and deficiencies in the above separation technologies are: the cost of the separation process is high; the organic extractant used will pollute the environment to a certain extent, which is not in line with the purpose of current green chemistry; the use of stripping agent will introduce other substances into the system, Affects product purity to a certain extent; process is relatively complicated

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