The invention discloses a synthesis method of 2-cyanopyridine, and belongs to the field of
chemical engineering. According to the method, 2-
picoline and
ammonia are gasified, air is introduced, a catalyst is used for
ammoxidation reaction, a combined three-stage spraying absorption
tower is adopted, gas obtained after
ammoxidation reaction is subjected to three-time absorption through a
sulfuric acid solution, two-time extraction is conducted through
benzene, washing and replacement are conducted through water, the
absorption rate of the product 2-cyanopyridine is maximized, and the yield of the product 2-cyanopyridine is increased. The product yield reaches 90% or above; meanwhile, the absorption amount of the
ammonia gas is greatly increased, so that the
ammonia gas in the reaction gas is efficiently recovered, the content of the
ammonia gas in the treated
tail gas is lower than 50mg / m < 3 >, the discharged
tail gas is clean, and the
pollution to the
atmosphere is reduced. And since the salt formed by the reaction of the
sulfuric acid and the
ammonia gas is relatively stable, the solution absorbed once can be continuously recycled, no
sewage is discharged, and the cost is saved.