1、 Tar naphthalene
從煤焦油中分離出來的萘稱之為焦油萘 。在高溫煤焦油中萘約占8-12% 。從焦油精餾塔側線切取出溫度區間為210-230℃的萘油餾分，經過洗滌脫酚，再精餾分離輕組分，便可得到凝固點為78℃、純度為96%的工業萘 。
Naphthalene separated from coal tar is called tar naphthalene. In high-temperature coal tar, naphthalene accounts for about 8-12%. Naphthalene oil fraction with a temperature range of 210-230 ℃ is cut from the side line of the tar distillation tower, washed and dephenolized, and then distilled to separate the light components to obtain industrial naphthalene with a freezing point of 78 ℃ and a purity of 96%.
工業萘中含雜質硫茚(1-3%)、甲基萘(1-2%)及少量茚、焦油堿和焦油酸，經過進一步酸洗和蒸餾，可得到硫含量小于0.1%、凝固點為79℃的精萘 。若需要進一步精制使硫含量低于0.05%，則需采用加氫精制工藝 。
Industrial naphthalene contains impurities such as indene (1-3%), methylnaphthalene (1-2%) and a small amount of indene, tar base and tar 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 lower than 0.05%, the hydrofining process is required.
2、 Petroleum naphthalene
石油萘的原料來自于催化重整、催化裂化和烴類裂解等過程的重芳烴組分 。在催化重整油中，甲基萘的含量約為55% 。首先經過萃取和吸附，從原料餾分中分離出萘的各種同系物，然后采用催化臨氫脫烷基的方法，以Cr2O3-Al2O3為催化劑，在400-800℃和0.5-7兆帕下進行臨氫脫甲基反應，反應產物經冷卻氣相物質后，蒸餾除去輕組分苯、甲苯、二甲苯等，最后進一步精餾可得到石油萘產品 。
The raw material of petroleum naphthalene comes from the heavy aromatics components in catalytic reforming, catalytic cracking and hydrocarbon cracking. In the catalytic reforming oil, the content of methyl naphthalene is about 55%. First, various homologues of naphthalene are separated from the raw material fraction through extraction and adsorption, and then the hydrogenation demethylation reaction is carried out with Cr2O3-Al2O3 as catalyst at 400-800 ℃ and 0.5-7 MPa by catalytic hydrodealkylation method. The reaction product is cooled by gas phase substances, and the light components such as benzene, toluene, xylene, etc. are removed by distillation. Finally, the petroleum naphthalene product can be obtained by further distillation.
The product is purified by solvent absorption and solvent washing, and the purity can reach 99.73%.
It is estimated that an ethylene plant with an annual output of 300000 tons using light diesel oil as cracking feedstock can produce 90000 tons of tar by side, of which naphthalene and naphthalene have a potential of 40000 to 50000 tons.