One-step separation of phenols, aromatics and alkanes in direct coal liquefaction oil

Abstract

The invention relates to a method for separating phenol, arene and alkane in direct coal liquefaction effluent through a one-step method. The method comprises the steps that dimethyl sulfoxide or mixed solvent of dimethyl sulfone and sulfolane is selected as extracting solvent (solvent A for short), and the direct coal liquefaction effluent is directly divided into phenol, arene and alkane through an extraction and rectification means. Obtained cycloparaffin can be directly taken as fuel, the obtained arene can be taken as a chemical material, and a mixture of a phenolic compound and the solvent A which are retained at the kettle bottom can be subjected to water-organic solvent (solvent B for short) extraction to obtain the phenol. According to the method, the liquefaction effluent can be directly divided into the three compounds, and the advantages that the product purity is high, the operating technology is simple, the system energy consumption is low, and equipment is not corroded due to the fact that acid and base are not used are achieved; in addition, the solvent A, the solvent B and water which are used in the method can be recycled, therefore, waste liquid discharge is reduced, and environmental protection is facilitated.

Description

technical field [0001] The invention relates to the field of coal chemical industry, in particular to a method for separating phenols, aromatics and alkanes in direct coal liquefaction oil in one step. It belongs to the processing method of coal direct liquefaction industry in coal chemical industry. Background technique [0002] Coal direct liquefied oil (hereinafter referred to as liquefied oil) is rich in phenols, aromatics and alkanes. Among them, aromatic hydrocarbons are mainly hydrogenated aromatic hydrocarbons, and the main compounds in alkanes are naphthenes. The separation of the above three types of compounds is a necessary step to realize the value of liquefied oil: naphthenes are ideal aviation fuels; hydrogenated aromatics can be used as hydrogen-donating solvents or fuel additives; phenols are not conducive to the stability of fuel oil, and can be further refined through separation with high added value Chemicals. During the separation process of liquefied ...

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Problems solved by technology

Correspondingly, the problems faced by the separation process include: 1. The separation efficiency is low, and the separation process requires a multi-step separation process, thereby increasing the oil loss and reducing the product yield; 2. The separation cost is high, and the extraction target of the traditional extractant is Aromatics, and liquefied oil contains a large amount of aromatic compounds, which will inevitably require a large amount of solvents, thereby pushing up the cost of separation; 3. Impurity entrainment, traditional extraction processes (including alkali extraction, solvent extraction) will be introduced into the product Additional solvents, water, and even other inorganic salts may poison the catalysts in the later process or introduce side reactions; 4. The traditional process will also bring about equipment corrosion, phenolic wastewater and other environmental pollution problems

The amount of extractant used is not less than 2 times the solvent ratio, but it is still difficult to completely separate phenol and aromatic hydrocarbons. The pollution of phenol in dephenolized oil and the entrainment of oil in phenol make the product purity not high and the separation cost is high.

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