Patent ID: 7687676

Claim:
A process for the catalytic dehydrogenation of a paraffinic hydrocarbon having from 5 to 20 carbon atoms per molecule in a reaction zone at a temperature required to effect a conversion per pass of the paraffinic hydrocarbon through the reaction zone, the process comprising: a) passing a combined feed comprising the paraffinic hydrocarbon and any recycle streams to the reaction zone, the combined feed comprising the paraffinic hydrocarbon and any recycle streams together having a first water concentration and a first equivalent concentration of water precursors, the sum of the first water concentration and the first equivalent concentration being less than 10 wt-ppm based on the weight of the combined feed passed to the reaction zone, the reaction zone containing a dehydrogenation catalyst comprising a platinum group component and a promoter component supported on a carrier material, the temperature being a first temperature and the conversion per pass being a first conversion per pass; and b) increasing at least one of the water or the water precursors in the combined feed such that the combined feed has a second water concentration and a second equivalent concentration of water precursors, the sum of the second water concentration and the second equivalent concentration being at least 100 wt-ppm based on the weight of the combined feed passed to the reaction zone, after the conversion per pass is at least 0.1 molar percentage points less than the first conversion per pass, and maintaining the reaction zone at a temperature that is not more than or is substantially the same as the first temperature.