PROCESS TO PREPARE PARAFFINS AND WAXES

摘要

The present invention relates to a process to prepare paraffins and waxes from a gaseous feed stream comprising hydrogen and carbon monoxide in a Fischer-Tropsch reactor comprising a fixes bed of reduced Fischer-Tropsch catalyst that comprises cobalt as catalytically active metal, said process at least comprises the following steps : (a) adding to the gaseous feed stream a nitrogen- containing compound such that the nitrogen-containing compound is present in the gaseous feed stream in a concentration of up to 10 ppmV to obtain a mixture, wherein the nitrogen-containing compound is a compound selected from ammonia, HCN, NO, amines, organic cyanides (nitriles), and a heterocyclic compound containing at least one nitrogen atom as ring member of a heterocyclic ring; (b) feeding the mixture of step (a) to the Fischer- Tropsch reactor to obtain a Fischer-Tropsch product comprising paraffins having from 5 to 300 carbon atoms; (c) subjecting the Fischer-Tropsch product of step (b) to a hydrogenation step, thereby obtaining hydrogenated fraction comprising 5 to 300 carbon atoms; (d) separating the hydrogenated Fischer-Tropsch product stream of step (c), thereby obtaining at least a fraction comprising 5 to 9 carbon atoms, a fraction comprising 10 to 17 carbon atoms and a fraction comprising 18 to 300 carbon atoms; (e) separating the hydrogenated fraction comprising 18 to 300 carbon atoms of step (d), thereby obtaining one or more first light waxes having a congealing point in the range of 30 to 75 °C and a second heavy wax having a congealing point in the range of 75 to 120°C.