Xylene is a colorless and transparent liquid;It is a product in which two hydrogens on the benzene ring are replaced by methyl,and there are three isomers:ortho,meta,and para.In industry,xylene refers to a mixture of the above isomers.
Xylene has a pungent odor,is flammable,and can mix freely with ethanol,chloroform,or ether.It is insoluble in water.The boiling point is 137-140℃.Xylene belongs to the low toxicity class of chemicals,and is classified as Class A4 by the American Conference of Government Industrial Hygienists(ACGIH),meaning it lacks evidence of carcinogenicity to humans and animals.Plastic,fuel,rubber,additives for various coatings,as well as various adhesives and waterproof materials,can also come from the combustion gases of fuel and tobacco leaves.
Security measures
Store in a low-temperature ventilated area,away from sources of fire and heat.Avoid co storage and transportation with oxidants and other substances.Do not use tools that are prone to sparking
Fire extinguishing:foam,carbon dioxide,dry powder,sand.
Production method:
1.Extract the fraction with a boiling range of 135~145℃by distillation based on the different boiling points of each component of crude benzene,and obtain xylene.
2.The platinum reforming method uses atmospheric distillation to obtain light gasoline(with an initial boiling point of about 138℃).The fraction above 65℃is cut and first catalyzed by a molybdenum containing catalyst to remove harmful impurities through hydrogenation.Then,it is reformed using a platinum catalyst,extracted with diethylene glycol ether solvent,and then distilled tower by tower to obtain products such as benzene,toluene,and xylene.
3.Toluene disproportionation method.This method involves transferring a methyl group of toluene to another 166 catalyst(aluminum deficient hydrogen type zeolite)under the action of a catalyst,using reformed toluene(nitration grade)and reformed recycle hydrogen(85%~90%)as raw materials,at a reaction temperature of 400±2℃and a pressure of about 2MPa,to produce benzene and xylene.
4.Mixing light petroleum fractions with benzene through hydrogenation refining,catalytic reforming,and separation to obtain xylene.Or it can be obtained by washing and distilling coking crude benzene.
effect:
Widely used as solvents in industries such as coatings,resins,dyes,inks,etc;Used for synthesizing monomers or solvents in industries such as pharmaceuticals,explosives,pesticides,etc;It can also be used as a component of high octane gasoline and is an important raw material for organic chemistry.It can also be used to remove asphalt from car bodies.The pathology department of the hospital is mainly used for transparency and dewaxing of tissues and sections.
Industrial ortho xylene is used as raw material.First,it is washed with industrial concentrated sulfuric acid until the acid layer is colorless.Then,it is washed with 10%sodium hydroxide solution and water in sequence until it is qualified.After separating the water layer,it is dried with anhydrous calcium chloride and then distilled.After the distillate is clear,the middle fraction is collected to obtain the pure product.