METHOD OF ISOLATING PHTHALIC ANHYDRIDE Russian patent published in 2002 - IPC

FIELD: methods of isolating phthalic anhydride from phthalo-air mixture. SUBSTANCE: phthalic anhydride is isolated in liquid form in partial condenser from phthalo-air mixture which is presaturated in evaporator with phthalic anhydride to concentration of 120-125 g/cubic m when cooling to 160-170 C as said mixture is mixed with phthalic anhydride suspension or solution in high-boiling liquid having boiling temperature of higher than 300 C and which are formed in desublimation column in counter flow motion of high-boiling liquid cooled to 45-55 C and uncondensed reaction products having temperature of 140-150 C and phthalic anhydride concentration of 80-85 g/cubic m and heated in partial condenser to temperature of 120-140 C. EFFECT: improved quality of phthalic anhydride isolated in liquid form, decreased material expenditure, lower energy and production losses. 1 dwg