Naphthalene, also known as naphthalene, is a colorless and shiny flake crystal. Insoluble in water, easy to sublimate, can volatilize with water vapor and has a special smell. It is an important polycyclic aromatic hydrocarbon in industry. It can be used in the production of phthalic anhydride, dye intermediates, rubber additives and pesticides. According to different purity, naphthalene can be divided into industrial naphthalene and refined naphthalene. The purity of industrial naphthalene is generally about 96%. After further purification, impurity removal and desulfurization of industrial naphthalene, high-purity refined naphthalene can be obtained.

白色易挥发晶体，有温和芳香气味，粗萘有煤焦油臭味；蒸汽压0.13kPa/52.6℃闪点：80℃；熔点80.1℃沸点217.9℃；不溶于水，溶于无水乙醇、醚、苯，相对密度（水=1）1.16;相对密度（空气=1）。稳定性：稳定；危险标记：（易燃固体）；主要用途：用于制造染料中间体、皮革、木材保护剂等。

White volatile crystal with mild aromatic smell, crude naphthalene with coal tar smell; Steam pressure: 0.13kpa/52.6 ℃, flash point: 80 ℃; Melting point 80.1 ℃, boiling point 217.9 ℃; Insoluble in water, soluble in absolute ethanol, ether and benzene, relative density (water = 1) 1.16; Relative density (air = 1). Stability: stable; Hazard marking: (flammable solid); Main uses: used for manufacturing dye intermediates, leather, wood protectants, etc.

焦油萘从煤焦油中分离出来的萘称之为焦油萘。在高温煤焦油中萘约占8-12%.从焦油精馏塔侧线切取出温度区间为210-230℃的萘油馏分，经过洗涤脱酚，再精馏分离轻组分，便可得到凝固点为78℃、纯度为96%的工业萘。

Tar naphthalene the naphthalene separated from coal tar is called tar naphthalene. Naphthalene accounts for about 8-12% in high-temperature coal tar. The naphthalene oil fraction with temperature range of 210-230 ℃ is cut from the side line of tar distillation tower, washed and dephenolized, and then the light components are separated by distillation to obtain industrial naphthalene with freezing point of 78 ℃ and purity of 96%.

工业萘中含杂质硫茚（1-3%）、甲基萘（1-2%）及少量茚、焦油碱和焦油酸，经过进一步酸洗和蒸馏，可得到硫含量小于0.1%、凝固点为79℃的精萘。若需要进一步精制使硫含量低于0.05%,则需采用加氢精制工艺。

Industrial naphthalene contains impurities indene (1-3%), methylnaphthalene (1-2%) and a small amount of indene, tar alkali and pyrooleic acid. After further pickling and distillation, refined naphthalene with sulfur content less than 0.1% and freezing point of 79 ℃ can be obtained. If further refining is required to make the sulfur content less than 0.05%, hydrofining process shall be adopted.

用工业萘小批量生产精萘的流程如下：将硫酸加入熔融的萘中脱水，搅拌后静置分离废酸。再加入98%的硫酸，在85-95℃条件下搅拌40分钟，静置分离废酸。在搅拌下加入37%的甲醛溶液在85-95℃条件下搅拌50分钟，加温水搅拌后静置，分层聚合物及磺化物料。用10%氢氧化钠溶液中和PH到7-8,静置后除去废碱。蒸馏冷却可得到精萘产品。

The process of small batch production of refined naphthalene from industrial naphthalene is as follows: add sulfuric acid into molten naphthalene for dehydration, stir and stand to separate waste acid. Add 98% sulfuric acid, stir at 85-95 ℃ for 40 minutes, and stand to separate the waste acid. Add 37% formaldehyde solution under stirring, stir at 85-95 ℃ for 50 minutes, stir with warm water and stand, and layer the polymer and sulfonated material. Neutralize pH to 7-8 with 10% sodium hydroxide solution, and remove waste alkali after standing. Refined naphthalene can be obtained by distillation and cooling.

石油萘石油萘的原料来自于催化重整、催化裂化和烃类裂解等过程的重芳烃组分。在催化重整油中，甲基萘的含量约为55%.首先经过萃取和吸附，从原料馏分中分离出萘的各种同系物，然后采用催化临氢脱烷基的方法。

Petroleum naphthalene the raw material of petroleum naphthalene comes from heavy aromatic components in catalytic reforming, catalytic cracking and hydrocarbon cracking. In the catalytic reforming oil, the content of Methylnaphthalene is about 55%. Firstly, various homologues of naphthalene are separated from the raw material fraction through extraction and adsorption, and then the catalytic hydrodealkylation method is adopted.

以Cr2O3-Al2O3为催化剂，在400-800℃和0.5-7兆帕下进行临氢脱甲基反应，反应产物经冷却气相物质后，蒸馏除去轻组分苯、甲苯、二甲苯等，进一步精馏可得到石油萘产品。产品用溶剂吸收和溶剂洗涤的方法进行提纯，纯度可达99.73%.

With Cr2O3-Al2O3 as catalyst, the hydrodemethylation reaction is carried out at 400-800 ℃ and 0.5-7 MPa. After cooling the gas phase substances, the reaction products are distilled to remove the light components such as benzene, toluene and xylene. Petroleum naphthalene products can be obtained by further distillation. The product was purified by solvent absorption and solvent washing, and the purity was 99.73%