Process to Produce a Gas Oil by Catlaytic Cracking of a Fisher-Tropsch Product

Abstract

Process to prepare a gas oil, by (a) isolating from a Fischer-Tropsch synthesis product a first gas oil fraction and a fraction boiling above the gas oil fraction, (b) contacting the heavier fraction with a catalyst system comprising a catalyst, which catalyst comprises an acidic matrix and a large pore molecular sieve in a riser reactor at a temperature of between 450 and 650° C. at a contact time of between 1 and 10 seconds and at a catalyst to oil ratio of between 2 and 20 kg/kg, (c) isolating from the product of step (b) a second gas oil fraction; (d) combining the first gas oil fraction with the second gas oil.

1 . A process to prepare a gas oil, by 
 (a) isolating from a Fischer-Tropsch synthesis product a first gas oil fraction and a heavier fraction boiling above the gas oil fraction;    (b) contacting the heavier fraction with a catalyst system comprising a catalyst, which catalyst comprises an acidic matrix and a large pore molecular sieve in a riser reactor at a temperature of between 450 and 650° C. at a contact time of between 1 and 10 seconds and at a catalyst to oil ratio of between 2 and 20 kg/kg;    (c) isolating from the product of step (b) a second gas oil fraction; and    (d) combining the first gas oil fraction with the second gas oil fraction.    
   
   
       2 . The process according to  claim 1 , wherein the heavier fraction used in step (b) has a weight ratio of compounds having at least 60 or more carbon atoms, and compounds having at least 30 carbon atoms, of at least 0.2, and wherein at least 30 wt % of the compounds have at least 30 carbon atoms.  
   
   
       3 . The process according to  claim 2 , wherein at least 50 wt % of the compounds in the heavier fraction used in step (b) have at least 30 carbon atoms.  
   
   
       4 . The process according to  claim 3 , wherein the weight ratio of compounds having at least 60 or more carbon atoms, and compounds having at least 30 carbon atoms, in the Fischer-Tropsch product is at least 0.4, in the heavier fraction used in step (b).  
   
   
       5 . The process according to  claim 1 , wherein the temperature in step (b) is below 600° C.  
   
   
       6 . The process according to  claim 1 , wherein the acidic matrix is alumina.  
   
   
       7 . The process according to  claim 1 , wherein the large pore molecular sieve is of the Faujasite type.  
   
   
       8 . The process according to  claim 1 , wherein the catalyst system in step (b) also comprises zeolite beta, Erionite, Ferrierite, ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, or ZSM-57.  
   
   
       9 . The process according to  claim 8 , wherein iso and normal pentenes and/or iso and normal hexenes produced in step (b) are subjected to an oligomerisation step to prepare compounds boiling in the gas oil range and wherein said compounds are combined with the gas oil product as obtained in step (d).  
   
   
       10 . The process according to  claim 1 , wherein the Fischer-Tropsch synthesis product used as feed in step (a) is obtained by means of a cobalt-catalyzed Fischer-Tropsch synthesis process.  
   
   
       11 . The process according to  claim 10 , wherein the cobalt catalyst is obtained by (aa) mixing (1) titania or a titania precursor, (2) a liquid, and (3) a cobalt compound, which is at least partially insoluble in the amount of liquid used, to form a mixture; (bb) shaping and drying of the mixture thus obtained; and (cc) calcination of the composition thus obtained.