-結晶法(見萘熔融-結晶精制)、加氫法(見萘加氫精制)、酸洗蒸餾法、溶劑結晶法、CO2氣體反溶劑法，升華法和甲醛法等。（1）溶劑結晶法制取精萘工藝，它是以焦化廠，煤氣廠的廢萘渣或焦油渣(又稱黑渣)為原料，經加溫蒸餾截取餾分為工業萘的部分，再與溶劑混溶加溫溶解，全溶后逐漸降溫至室溫，重新結晶，再經分離，干燥制成產品精萘。也可直接采用工業萘或生產工業萘過程中排出的水萘作提取精萘的原料。該工藝設備簡單，操作容易，周期短，產品質量穩定，無環境污染。

The production methods of refined naphthalene mainly include melting crystallization method (see naphthalene melting crystallization refining), hydrogenation method (see naphthalene hydrogenation refining), acid washing distillation method, solvent crystallization method, CO2 gas anti solvent method, sublimation method, and formaldehyde method. (1) The solvent crystallization method for producing refined naphthalene is a process that uses waste naphthalene residue or tar residue (also known as black residue) from coking plants and gas plants as raw materials. The distillate is then heated and distilled to extract a portion of industrial naphthalene, which is then mixed with the solvent and heated for dissolution. After complete dissolution, it is gradually cooled to room temperature, recrystallized, separated, and dried to produce refined naphthalene. Industrial naphthalene or water naphthalene discharged during the production process can also be directly used as the raw material for extracting refined naphthalene. This process has simple equipment, easy operation, short cycle, stable product quality, and no environmental pollution.

（2）甲醛法：粗萘中的不飽和化合物和硫Chemicalbook茚等雜質在酸性介質中與甲醛縮聚成樹脂狀物質，經分離除去。熔融的粗萘先經濃硫酸脫水和縮聚，再用甲醛硫酸溶液進一步縮聚，分離除去樹脂層，然后經加堿中和、水洗、精餾、切片，即得結晶點大于79.3℃的精萘。萘精制率約為90%。也可不經濃硫酸脫水和縮聚工序，直接用甲醛硫酸溶液精制。

(2) Formaldehyde method: Unsaturated compounds and impurities such as sulfur chemicalbook indene in crude naphthalene are condensed with formaldehyde in an acidic medium to form resin like substances, which are separated and removed. The molten crude naphthalene is first dehydrated and condensed with concentrated sulfuric acid, and then further condensed with formaldehyde sulfuric acid solution to separate and remove the resin layer. Then, it is neutralized with alkali, washed with water, distilled, and sliced to obtain refined naphthalene with a crystallization point greater than 79.3 ℃. The refining rate of naphthalene is about 90%. It can also be refined directly with formaldehyde sulfuric acid solution without undergoing concentrated sulfuric acid dehydration and condensation processes.

（3）CO2氣體反溶劑法：其主要優點在于工藝簡單、操作溫度低（常溫），選擇合適的溶劑很容易使萘的純度達到98%以上。二次結晶后可實現進一步純化，獲得純度99%的高純萘。CO2氣體和有機溶劑均可以回收利用，節能效果顯著。精萘上下游產品信息

(3) CO2 gas anti solvent method: Its main advantages are simple process, low operating temperature (room temperature), and selecting a suitable solvent can easily achieve a purity of over 98% for naphthalene. After secondary crystallization, further purification can be achieved to obtain high-purity naphthalene with a purity of 99%. CO2 gas and organic solvents can be recycled and reused, with significant energy-saving effects. Information on upstream and downstream products of refined naphthalene