Widely used in coatings, resins, dyes, inks and other industries as solvents; used in pharmaceuticals, explosives, pesticides and other industries as synthetic monomers or solvents; can also be used as a high octane gasoline component, is an important raw material for organic chemicals. It can also be used to remove asphalt from the car body. Hospital pathology department is mainly used for the transparency and dewaxing of tissues and sections. Industrial o-xylene is used as a raw material, first washed with industrial concentrated sulfuric acid until the acid layer is colorless, and then sequentially washed with 10% sodium hydroxide solution and water until qualified, the aqueous layer is separated, dried over anhydrous calcium chloride, and then rectified, After the distillate is clear, the middle distillate is collected, which is pure.
1. According to the boiling point of each component of crude benzene, a fraction with a boiling range of 135 to 145 ° C is extracted by distillation to obtain xylene.
2. The platinum reforming method uses normal pressure distillation of light gasoline (the initial boiling point is about 138 ° C), cuts the fractions greater than 65 ° C, firstly removes the harmful impurities by catalytic hydrogenation through a molybdenum-containing catalyst, and then reforms through a platinum catalyst Extraction with diethylene glycol ether solvent, and then rectification column by column, to obtain products such as benzene, toluene and xylene.
3, toluene disproportionation method. In this method, a methyl group of one toluene is transferred to another 166 catalyst (aluminum-hydrogen-type mordenite) under the action of a catalyst, and reformed toluene (nitrification grade) and reformed recycled hydrogen (85% -90%) are used as raw materials. Under the conditions of a reaction temperature of 400 ± 2 ° C and a pressure of about 2 MPa, benzene and xylene were prepared by the reaction.
4. Mixing petroleum light fraction with benzene through hydrorefining, catalytic reforming, and separation to obtain xylene. Or the coked crude benzene is obtained by washing and fractional distillation.