Method for stepwise extraction of phenol and pyridine compounds in naphthalene oil by deep eutectic solvents

A method for stepwise extraction of phenol and pyridine compounds in naphthalene oil by deep eutectic solvents, comprising the following steps:

• step 1, mixing the naphthalene oil, alkane and the deep eutectic solvents, and performing phase separation to obtain a heteroatom eutectic phase and a hydrocarbon raffinate phase;
• step 2, mixing the heteroatom eutectic phase with a first stripping agent, and performing phase separation to obtain a first stripping organic phase and a first stripping raffinate phase;
• step 3, separating a heteroatom mixture in the first stripping organic phase from the first stripping agent by distillation, mixing the heteroatom mixture, alkane and a hydrogen bond acceptor extractant, and performing phase separation to obtain a phenol eutectic extracting phase and a pyridine raffinate phase;
• and
• step 4, mixing the phenol eutectic extracting phase with a second stripping agent, and performing phase separation to obtain a phenol compound;
• wherein, the deep eutectic solvents are a mixture of at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide, and at least one of a glycolic acid, an oxalic acid, a citric acid and a p-toluenesulfonic acid;
• and the hydrogen bond acceptor extractant is at least one of tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylphosphonium bromide.