Resumen
(Amendments Included) SUBJECT OF THE INVENTION The low-cost silicate system catalyst easily isolate|separated from the reaction medium by filtration or centrifugation is used, Provision of the process of manufacturing highly purified isocyanate easily and economically with high reaction rate, a selectivity, and a yield from a carbamate. PROBLEM TO BE SOLVED The method to use nature or a synthetic|combination silicate for a catalyst, and to manufacture isocyanate by catalyst thermal decomposition in an organic solvent from a carbamate. Moreover, a natural silicate is clay especially a montmorillonite, or an H<+> modified|denatured bentonite, The method a synthetic|combination silicate is a zeolite especially ZSM-5, TS-1, TS-2, ZSM-11, Linde X, Linde Y, a faujesite, or a mordenite. As a carbamate, a montmorillonite is illustrated as 1, 2- dichlorobenzene and a catalyst as N- carbomethoxy aniline and a solvent, respectively.