Mechanism for the preparation of hydrogen iodide from iodine

On the basis of experiments,a new reaction mechanism for the preparation of hydrogen iodide from iodine was proposed.There are two competitive reactions in the process of hyrogen iodide's preparation.One is the main reaction in which the hydrogen iodide is formed.The other one is the water-gas shift reaction which produces hydrogen.The hydrogen which is produced through the water's nucleophilicly attacking to the trivalence carbonyl rhodium complex will quickly react with complex iodine to form hydrogen iodide.When the iodine is consumed,the water-gas shift reaction occurs.