精萘是一种重要的有机化工原料，广泛应用于染料、医药、塑料、农药等领域。其提取主要依赖于煤焦油和石油化工副产物，以下是当前工业中主流的提取与精制方法：

Naphthalene is an important organic chemical raw material widely used in fields such as dyes, pharmaceuticals, plastics, pesticides, etc. Its extraction mainly relies on coal tar and petrochemical by-products. The following are the mainstream extraction and refining methods in the current industry:

一、煤焦油提取法（传统主流工艺）

1、 Coal tar extraction method (traditional mainstream process)

煤焦油是煤炭干馏的副产物，其中萘的含量约为 8%-12%，是提取精萘的主要原料。具体流程如下：

Coal tar is a by-product of coal dry distillation, with a naphthalene content of about 8% -12%, and is the main raw material for extracting refined naphthalene. The specific process is as follows:

1. 原料预处理与分馏

1. Raw material pretreatment and fractionation

分馏切取萘油馏分：将煤焦油在蒸馏塔中加热，按沸点范围切取**210-270℃**的馏分段（称为 “萘油” 或 “中油”），其中萘含量可达 50%-70%，同时含有酚类、喹啉、甲基萘等杂质。

Fractionation and extraction of naphthalene oil fractions: Coal tar is heated in a distillation tower and a fraction of * * 210-270 ℃ * * is extracted according to the boiling point range (referred to as "naphthalene oil" or "middle oil"), with a naphthalene content of up to 50% -70% and impurities such as phenols, quinolones, and methyl naphthalene.

2. 粗萘分离

2. Separation of crude naphthalene

冷却结晶与离心：将萘油冷却至50-60℃，萘从油中结晶析出，通过离心机分离得到粗萘（纯度约 90%-95%），杂质主要为酚类、喹啉及高沸点油类。

Cooling crystallization and centrifugation: naphthalene oil is cooled to 50-60 ℃, and naphthalene crystallizes and precipitates from the oil. Crude naphthalene (with a purity of about 90% -95%) is separated by centrifugation, and impurities mainly include phenols, quinolines, and high boiling point oils.

3. 粗萘精制

3. Crude naphthalene refining

溶剂洗涤除杂：

Solvent washing for impurity removal:

用浓硫酸洗涤粗萘，去除其中的不饱和烃和酚类杂质；

Wash crude naphthalene with concentrated sulfuric acid to remove unsaturated hydrocarbons and phenolic impurities;

再用氢氧化钠溶液中和残留酸，水洗后干燥。

Neutralize the residual acid with sodium hydroxide solution, wash with water, and then dry.

升华或蒸馏精制：

Sublimation or distillation refinement:

升华法：利用萘的升华特性（熔点 80.2℃，沸点 218℃），在加热条件下使萘直接从固态变为气态，冷凝后得到纯度≥99% 的精萘。

Sublimation method: Utilizing the sublimation properties of naphthalene (melting point 80.2 ℃, boiling point 218 ℃), naphthalene is directly transformed from solid to gas under heating conditions, and condensed to obtain refined naphthalene with a purity of ≥ 99%.

蒸馏法：将粗萘在蒸馏塔中减压蒸馏，利用各组分沸点差异分离，馏出的萘蒸气冷凝后即为精萘。

Distillation method: Crude naphthalene is distilled under reduced pressure in a distillation tower, and the boiling point differences of each component are used to separate it. The distilled naphthalene vapor is condensed and becomes refined naphthalene.

二、石油化工副产物提取法（新兴工艺）

2、 Extraction method of by-products from petrochemical industry (emerging process)

随着石油化工的发展，从催化重整生成的重芳烃（如石脑油重整副产物）中提取萘成为补充途径，流程如下：

With the development of petrochemicals, extracting naphthalene from heavy aromatic hydrocarbons generated by catalytic reforming (such as by-products of naphtha reforming) has become a supplementary pathway. The process is as follows:

1. 重芳烃分离

1. Separation of heavy aromatic hydrocarbons

催化重整生成的重芳烃中含有萘及烷基萘，通过溶剂萃取（如环丁砜、二甲基亚砜）或结晶法（利用低温下萘的结晶特性）分离出萘的富集物。

The heavy aromatic hydrocarbons generated by catalytic reforming contain naphthalene and alkyl naphthalene, and the enriched naphthalene can be separated by solvent extraction (such as sulfolane, dimethyl sulfoxide) or crystallization (utilizing the crystallization characteristics of naphthalene at low temperatures).

2. 催化加氢精制

2. Catalytic hydrogenation refining

对富集物进行催化加氢，去除硫、氮等杂质，同时将烷基萘转化为萘，再通过蒸馏或结晶得到精萘。

Catalytic hydrogenation of the enriched material to remove impurities such as sulfur and nitrogen, while converting alkyl naphthalene to naphthalene, and then obtaining refined naphthalene through distillation or crystallization.

该方法所得精萘纯度高（≥99.5%），杂质少，适合高端应用场景。

The purity of refined naphthalene obtained by this method is high (≥ 99.5%), with few impurities, suitable for high-end application scenarios.

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