Reivindicaciones

1. A procedure for the production of isocyanates from carbamates by catalytic thermal decomposition, characterised in that natural or synthetic silicates are used as catalysts. 2. Procedure in accordance with claim 1, characterised in that the natural silicates are clays. 3. Procedure in accordance with claim 1, characterised in that the natural or synthetic silicates are zeolites. 4. Procedure in accordance with claim 1 or 2, characterised in that the clays are montmorillonites. 5. Procedure in accordance with claim 1 or 2, characterised in that the clays are modified bentonites in their H<+> form. 6. Procedure in accordance with claim 1 or 3, characterised in that the zeolites used are selected from ZSM-5, TS-1, TS-2, ZSM-11, Linde X, Linde Y, Faujesite, Mordenite and their mixes. 7. Procedure in accordance with any of claims 1 to 6, characterised in that the natural or synthetic silicates are calcinated before the reaction. 8. Procedure in accordance with any of claims 1 to 6, characterised in that the natural or synthetic silicates are treated previously with organic or inorganic acids. 9. Procedure in accordance with any of claims 1 to 6, characterised in that the natural or synthetic silicates are treated previously with ammonia or with organic bases. 10. Procedure in accordance with claim 1, characterised in that the reaction temperature is between 150°C and 300°C, preferably between 200°C and 275°C.