METHOD OF PREPARING VINYL AROMATIC HYDROCARBON Russian patent published in 2001 - IPC

FIELD: petrochemical industry, more particularly production of vinyl aromatic hydrocarbon, e.g. styrene, alpha-methyl styrene, divinyl benzene. SUBSTANCE: in method of preparing vinyl aromatic hydrocarbon by catalytic dehydrogenation of alkyl aromatic hydrocarbon in multistage reactor in the presence of steam in vacuum; evaporation and overheating of alkyl aromatic hydrocarbon are carried out in vacuum of 0.8-0.9 atm in admixture with purified steam condensate at 1:0.3 weight ratio or in mixture of alkyl aromatic hydrocarbon, steam condensate at 1:0.2: 0.1 weight ratio. Said mixture is heated by using heat of steam condensate circulating in foam apparatus, evaporation and initial overheating are carried out by indirect contact with mixture of steam admitted from boiler utilizers and interstage overheater of contact gas, and final overheating is carried out by using heat of contact gas after last dehydrogenation stage. EFFECT: lower specific steam consumption for evaporation purposes and overheated alkyl aromatic hydrocarbon, and formation of highly boiling by-products. 2 cl, 1 dwg, 6 ex