Process to prepare normal paraffins

Abstract

A process for preparing normal paraffin involves separating a Fischer-Tropsch product stream to obtain first gaseous and liquid hydrocarbon streams. The first gaseous hydrocarbon stream is cooled and separated to obtain a second liquid hydrocarbon stream and a third liquid hydrocarbon stream, which are separated by atmospheric distillation, to obtain a normal paraffin fraction comprising 5 to 9 carbon atoms and a normal paraffin fraction comprising 10 to 35 carbon atoms. The normal paraffin fraction comprising 10 to 35 carbon atoms is separated by atmospheric distillation to obtain a normal paraffin fraction comprising 10 to 18 carbon atoms and a normal paraffin fraction comprising 19 to 35 carbon atoms. The fraction comprising 10 to 18 carbon atoms hydrogenated (a) and separated to obtain a normal paraffin comprising 10 to 13 carbon atoms and a normal paraffin comprising 14 to 18 carbon atoms.

1 . A process to prepare normal paraffins, the process comprises the steps of:
 (a) providing a Fischer-Tropsch product stream;   (b) separating the Fischer-Tropsch product stream of step (a), thereby obtaining a first gaseous hydrocarbon stream and a first liquid hydrocarbon stream;   (c) cooling and separating of the first gaseous hydrocarbon stream of step (b) in one or more steps to obtain a second liquid hydrocarbon stream and a third liquid hydrocarbon stream;   (d) separating the second and the third liquid hydrocarbon streams of step (c) by atmospheric distillation, thereby obtaining a normal paraffin fraction comprising 5 to 9 carbon atoms and a normal paraffin fraction comprising 10 to 35 carbon atoms;   (e) separating the normal paraffin fraction comprising 10 to 35 carbon atoms of step (d) by atmospheric distillation, thereby obtaining a normal paraffin fraction comprising 10 to 18 carbon atoms and a normal paraffin fraction comprising 19 to 35 carbon atoms;   (f) hydrogenation of the normal paraffin fraction comprising 10 to 18 carbon atoms of step (e) to obtain a hydrogenated normal paraffin fraction comprising 10 to 18 carbon atoms;   (g) separation of the hydrogenated normal paraffin fraction comprising 10 to 18 carbon atoms as obtained in step (f), thereby obtaining a normal paraffin comprising 10 to 13 carbon atoms and a normal paraffin comprising 14 to 18 carbon atoms.   
     
     
         2 . The process according to  claim 1 , wherein the Fischer-Tropsch product stream of step (a) is separated in step (b) at a temperature in a range of from 160 to 350° C. and at a pressure in a range of from 5 to 150 bar. 
     
     
         3 . The process according to  claim 1 , wherein the first gaseous hydrocarbon stream of step (b) is cooled and separated in step (c) at a temperature in a range of from 5 to 180° C. and at pressure in a range of from 5 to 145 bar. 
     
     
         4 . The process according to  claim 1 , wherein the first gaseous hydrocarbon stream of step (b) is cooled and separated in two steps in step (c). 
     
     
         5 . The process according to  claim 1 , wherein the atmospheric distillation in steps (d) and (e) is at a temperature in the range of 200 to 400° C. 
     
     
         6 . The process according to  claim 1 , wherein the separation of the second and the third liquid hydrocarbon liquid streams of step (c) in steps (d) and (e) is done in one separation step by atmospheric distillation. 
     
     
         7 . The process according to  claim 1 , wherein prior to the separation in step (d) the second and the third liquid hydrocarbon liquid stream are combined. 
     
     
         8 . The process according to  claim 1 , wherein the weight fraction of the normal paraffin comprising 10 to 13 carbon atoms is between 45 and 60 wt. % and the weight fraction of the normal paraffin comprising 14 to 17 is between 40 and 55 wt. % based on the amount of the hydrogenated liquid hydrocarbon stream of step (f). 
     
     
         9 . The process according to  claim 1 , wherein the normal paraffin comprising 10 to 13 carbon atoms of step (g) comprises a fraction comprising 10 carbon atoms in a range of from 10 to 11 wt. %, a fraction comprising 11 carbon atoms in a range of from 30 to 32 wt. %, a fraction comprising 12 carbon atoms in a range of from 30 to 32 wt. % and a fraction comprising 13 carbon atoms in a range of from 23 to 26 wt. %. 
     
     
         10 . The process according to  claim 1 , wherein the normal paraffin comprising 14 to 18 carbon atoms of step (g) comprises a fraction comprising 14 carbon atoms in a range of from 25 to 27 wt. %, a fraction comprising 15 carbon atoms in a range of from 24 to 26 wt. %, a fraction comprising 16 carbon atoms in a range of from 22 to 23 wt. %, a fraction comprising 17 carbon atoms in a range of from 18 to 20 wt. % and a fraction comprising 18 carbon atoms in a range of from 4 to 6 wt. %. 
     
     
         11 . The process according to  claim 1 , wherein the Fischer-Tropsch product stream of step (a) is separated in step (b) at a temperature in a range of from 190 to 250° C. 
     
     
         12 . The process according to  claim 1 , wherein the atmospheric distillation in steps (d) and (e) is at a temperature in the range of 300 to 350° C. 
     
     
         13 . The process according to  claim 1 , wherein the weight fraction of the normal paraffin comprising 10 to 13 carbon atoms is 49 wt. % based on the amount of the hydrogenated liquid hydrocarbon stream of step (f). 
     
     
         14 . The process according to  claim 1 , wherein the weight fraction of the normal paraffin comprising 14 to 17 is 51 wt. % based on the amount of the hydrogenated liquid hydrocarbon stream of step (f).