The naphthalene extracted from coal tar is called tar naphthalene. In high-temperature coal tar, naphthalene accounts for approximately 8-12%. Cut the naphthalene oil fraction with a temperature range of 210-230 ℃ from the side line of the tar distillation tower, undergo cleaning and dephenolization, and then separate the light components through distillation to obtain industrial naphthalene with a solidification point of 78 ℃ and a purity of 96%.
Industrial naphthalene contains residues of thionines (1-3%), methyl naphthalene (1-2%), and small amounts of nines, tar alkali, and tar acid. After advanced acid washing, passivation, and steam distillation, refined naphthalene with a sulfur content below 0.1% and a solidification point of 79 ℃ can be obtained. If it is necessary to improve the special process to make the sulfur content less than 0.05%, then the hydrofining process needs to be selected.
The raw material of petroleum naphthalene comes from the heavy aromatic components of the entire process of catalytic reforming, catalytic cracking, and nitrogen compound cracking. In catalytic reforming oil, the water content of methyl naphthalene is about 55%. After purification and adsorption, various homologues of naphthalene were separated from the raw material fraction. Subsequently, a catalytic reaction was used for hydrodealkylation, using Cr2O3-Al2O3 as a metal catalyst. The hydrodemethylation reaction was carried out at 400-800 ℃ and 0.5-7 MPa. The reaction substance was cooled by liquid phase chemical substances, and the light components such as benzene, xylene, and xylene were removed by steam distillation. Finally, petroleum naphthalene products were obtained through progressive distillation. The product is purified using organic solvent digestion and absorption, as well as organic solvent cleaning, with a purity of 99.73%.
According to statistics, butadiene equipment with an annual production capacity of 300000 tons using light diesel as cracking raw material can produce 90000 tons of tar as a byproduct, among which naphthalene and naphthalene have a potential of 40000 to 50000 tons.
Industrial production of refined naphthalene is a basic raw material for chemical plants, suitable for the production and manufacturing of additives and external dispersants. It is a raw material for the production and manufacturing of resin materials, flame retardants, rubber antioxidants, surfactants, artificial fibers, dyes, pharmaceuticals, and spices.