Process for producing unsaturated nitrile

A process for producing unsaturated nitrile, the process comprising:

• providing a fluidized bed reactor having an internal space comprising a catalyst capable of being fluidized therein, a starting material feed opening to feed a starting material gas comprising hydrocarbon to the internal space, a dispersion plate to feed an oxygen-containing gas comprising oxygen to the internal space;
• a discharge port to discharge a reaction product gas from the internal space, and a cyclone to separate and recover the catalyst from the reaction product gas in the internal space;
• and
• a reaction step of subjecting the hydrocarbon to a vapor phase catalytic ammoxidation reaction in the presence of the catalyst in the internal space to produce the corresponding unsaturated nitrile, wherein
• when the internal space is divided into two spaces of an upper space occupying a space from an upper end of an inlet of the cyclone to an upper end of the internal space and a lower space occupying a space below the upper end of the inlet of the cyclone and ranging to the dispersion plate, a ratio of an existing amount of the catalyst in the upper space per unit volume to an existing amount of the catalyst in the lower space per unit volume is 0.05 to 0.45 in the reaction step, and
• the catalyst has a composition represented by the following formula (1):
• MoVaNbbXcTdZeOn (1)
• wherein X is one or more element selected from the group consisting of Sb and Te, T is one or more element selected from the group consisting of W and Mn, and Z is Ce, and
• a, b, c, d, e and n each represents an atomic ratio of each atom per Mo atom, and are in the ranges of 0.01≤a≤1, 0.01≤b≤1, 0.01≤c≤1, 0≤d≤1, and 0≤e≤1, and n is a value satisfying a balance of the valences.