工業萘中的雜質主要是與萘沸點較接近的四氫萘、硫雜?、二甲酚等。如萘的沸點(218℃)和硫?的沸點（219℃）相差不到2℃，因此為了制造純度更高的精萘，就要利用萘與這些雜質熔點不同的物理性質進行分離，或者利用化學方法來改變它們的化學組成。當前精萘的生產方法，有加氫精制法、酸洗蒸熘法、升華法、結晶法等。

The impurities in industrial naphthalene are mainly tetrahydronaphthalene and sulfur impurities, which have boiling points close to naphthalene Dimethylphenol, etc. Like the boiling point of naphthalene (218 ℃) and sulfur? The boiling point (219 ℃) of naphthalene is less than 2 ℃, so in order to produce higher purity refined naphthalene, it is necessary to separate naphthalene from these impurities by utilizing their different physical properties with different melting points, or use chemical methods to change their chemical composition. The current production methods for refined naphthalene include hydrogenation refining, acid washing and steaming, sublimation, crystallization, etc.

酸洗蒸熘法應用較早，但由千酸洗帶來嚴重腐蝕，萘損失率高，且廢酸難以處理，所以正趨于淘汰。

The acid washing and steaming method was applied earlier, but it is being phased out due to severe corrosion caused by thousand acid washing, high naphthalene loss rate, and difficulty in treating waste acid.

加氫精制法，萘的催化加氫多采用ai-co-mo催化劑，也有采用ai-ni-mo催化劑的。使萘中的硫?、苯甲腈、?、酚等雜質轉化成易于除去的物質加以分離。需指出的是在萘加氫凈化過程中，不希望生產四氫化萘，選擇適當的加氫凈化制度可以將四氫化萘的生成限制在0.3％以下（占加氫精萘）。萘的加氫精制主要用于生產低硫萘，這種萘用于流化床生產鄰苯二甲酸酐，可避免催化劑中毒，另外也適用千生產二萘酚、甲萘胺、h酸及苯胺染料中間體等化主產品，投資大、危險性大。

In the hydrogenation refining method, the catalytic hydrogenation of naphthalene is mostly carried out using ai co mo catalysts, and there are also cases where ai ni mo catalysts are used. Make sulfur in naphthalene Benzonitrile Phenols and other impurities are converted into easily removable substances for separation. It should be pointed out that in the process of naphthalene hydrogenation purification, it is not desired to produce tetrahydronaphthalene. Choosing an appropriate hydrogenation purification system can limit the generation of tetrahydronaphthalene to below 0.3% (accounting for hydrogenated naphthalene). The hydrogenation refining of naphthalene is mainly used to produce low sulfur naphthalene, which is used in fluidized bed production of phthalic anhydride to avoid catalyst poisoning. In addition, it is also suitable for the production of main chemical products such as naphthalene, methylnaphthylamine, H-acid, and aniline dye intermediates, with high investment and high risk.

升華法，萘在遠低千沸點時已具有較高的蒸汽壓。蔡蒸汽冷卻時可不經過液相直接凝結成固體。利用此性質，使原料中的萘與高沸點油類雜質分離，而得到純度高的升華萘，此法在現實生產中采用較少。

Sublimation method, naphthalene already has a high vapor pressure at a much lower boiling point. When Cai steam is cooled, it can directly condense into a solid without going through the liquid phase. By utilizing this property, naphthalene in the raw material can be separated from impurities in high boiling oil to obtain high-purity sublimated naphthalene, which is less commonly used in practical production.

結晶法：結晶法分為熔融結晶法和溶劑結晶法。

Crystallization method: Crystallization method is divided into melt crystallization method and solvent crystallization method.

熔融結晶法是利用?與雜質在醇類中溶解度的差異使萘得到凈化。溶劑結晶法使用的溶劑多數采用甲醇，甲醇足易燃易爆危險化學品，且有毒，危害很大，基本上很少采用熔融結晶法。

Is the melt crystallization method utilized? The difference in solubility between impurities and alcohols purifies naphthalene. The solvent used in solvent crystallization method mostly uses methanol, which is a flammable and explosive hazardous chemical and toxic, with great harm. Melt crystallization method is rarely used.

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