Naphthalene, also known as naphthalene, is a colorless and shiny crystalline flake. Insoluble in water, prone to sublimation, can evaporate with water vapor, and has a special odor. It is an important polycyclic aromatic hydrocarbon in industry and can be used as an intermediate in the production of phthalic anhydride, dyes, rubber additives, and insecticides. According to different purities, naphthalene can be divided into industrial naphthalene and refined naphthalene. So how are tar naphthalene and petroleum naphthalene produced? The following refined naphthalene manufacturer will analyze for you:
The naphthalene separated from coal tar is called tar naphthalene. Naphthalene accounts for 8-12% of high temperature coal tar. Cut naphthalene oil fraction with a temperature range of 210-230 ℃ from the side line of the tar distillation tower, wash and dephenolize it, and then distill and separate the light components to obtain industrial naphthalene with a solidification point of 78 ℃ and a purity of 96%.
Industrial naphthalene contains impurities such as sulfur indene (1-3%), methyl naphthalene (1-2%), and a small amount of indene, tar base, and tar acid. After progressive acid washing and distillation, refined naphthalene with a sulfur content of less than 0.1% and a solidification point of 79 ℃ can be obtained. If it is necessary to improve refining so that the sulfur content is below 0.05%, a hydrofining process is required.
The process of producing refined naphthalene in small batches using industrial naphthalene is as follows: adding sulfuric acid to molten naphthalene for dehydration, stirring, and then standing to separate the waste acid. Add 98% sulfuric acid again, stir at 85-95 ℃ for 40 minutes, and let stand to separate the waste acid. Add 37% formaldehyde solution under stirring and stir at 85-95 ℃ for 50 minutes. Stir with warm water and let stand. Layer the polymer and sulfonated material. Neutralize the pH to 7-8 with a 10% sodium hydroxide solution, and remove the waste alkali after standing. After distillation and cooling, refined naphthalene products can be obtained.
The feedstock of petroleum naphthalene comes from heavy aromatics in catalytic reforming, catalytic cracking and hydrocarbon cracking processes. The content of methylnaphthalene in catalytic reforming oil is about 55%. After extraction and adsorption, various homologues of naphthalene are separated from the raw material fraction. Then, a catalytic hydrodealkylation method is used, using Cr2O3-Al2O3 as catalyst, to undergo hydrodemethylation reaction at 400-800 ℃ and 0.5-7 MPa. The reaction product is cooled by gas phase substances, and the light components such as benzene, toluene, and xylene are removed by distillation. Then, petroleum naphthalene products can be obtained through further distillation. The product is purified using solvent absorption and solvent washing methods, with a purity of up to 99.73%.
It is estimated that an ethylene plant with an annual production of 300000 tons using light diesel as the cracking raw material can produce 90000 tons of tar as a byproduct, with a potential of 40-50000 tons of naphthalene and naphthalene.
Refined naphthalene can be used in dyes, pharmaceuticals, and other fields, such as the production of 2-naphthol, 1-naphthol, and methylnaphthylamine, and is also the main raw material for the production of camphor. If you have any usage needs, please come to our website for consultation or call us directly http://www.jnjdbc.cn Understand!