Catalyst regeneration vessels including a chlorination zone that includes an outer mixing chamber, an inner mixing chamber, and a catalyst bed. The outer mixing chamber can include a lower portion and an upper portion, the lower portion of the outer mixing chamber including at least one air nozzle that injects a drying air stream into the outer mixing chamber, at least one chlorine input nozzle that injects a chlorine input stream into the outer mixing chamber, and at least a first baffle. The chlorination zone can also contain a second baffle that directs the mixed drying air stream and chlorine input stream from the outer mixing chamber to the inner mixing chamber.