Process for co-producing jet fuel and lpg from renewable sources

Abstract

The present invention generally relates to a method for producing an isoparaffinic product useful as jet fuel from a renewable feedstock. The method may also include co-producing a jet fuel and a liquefied petroleum gas (LPG) fraction from a renewable feedstock. The method includes hydrotreating the renewable feedstock to produce a hydrotreating unit heavy fraction that includes n-paraffins and hydroisomerizing the hydrotreating unit heavy fraction to produce a hydroizomerizing unit heavy fraction that includes isoparaffins. The method also includes recycling the hydroisomerizing unit heavy fraction through the hydroisomerization unit to produce an isoparaffinic product that may be fractionated into a jet fuel and an LPG fraction. The present invention also relates to a jet fuel produced from a renewable feedstock having improved cold flow properties.

1 . A method for producing from a renewable feedstock an isoparaffinic product useful as jet fuel, the method comprising:
 a. hydrotreating a renewable feedstock with a diluent to produce an n-paraffinic fraction;   b. hydroisomerizing n-paraffinic fraction to produce an isoparaffinic fraction and a heavy fraction;   c. separating the heavy fraction from the isoparaffinic fraction; and   d. recycling the heavy fraction of step (c) to the hydroisomerizing step of step (b) and wherein the diluent comprises C3-C18 n-paraffins and/or iso-paraffins produced by at least one of the steps of the method.   
     
     
         2 . The method of  claim 1  further comprising the step of fractionating the isoparaffin to produce jet fuel. 
     
     
         3 . The method of  claim 1 , wherein the renewable feedstock comprises triglycerides, free fatty acids, and combinations thereof. 
     
     
         4 . The method of  claim 1 , wherein the renewable feedstock is selected from the group comprising animal fats, animal oils, vegetable fats, vegetable oils, rendered fats, restaurant grease, waste industrial frying oils, fish oils, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the hydrotreating step operating conditions comprise a reaction temperature of from about 300° F. to about 850° F. and a reaction pressure of from about 250 psig to about 3000 psig. 
     
     
         6 . The method of  claim 1  wherein the liquid hourly space velocity through the hydrotreating step is about 0.5 to about 5.0 h −1 . 
     
     
         7 . The method of  claim 1 , wherein the hydroisomerizing step operating conditions comprise a reaction temperature of from about 300° F. to about 850° F. and a reaction pressure of from about 250 psig to about 3000 psig. 
     
     
         8 . The method of  claim 1  wherein the hydrotreating step is carried out in the presence of a sulfided bimetallic catalyst. 
     
     
         9 . The method according to  claim 8  wherein the catalyst is a supported NiW, NiMo or a CoMo catalyst, the support being alumina. 
     
     
         10 . The method of  claim 1 , wherein the isoparaffinic product has a boiling point range of from about 150° C. to about 300° C. 
     
     
         11 . A method of co-producing liquid petroleum gases, isoparaffinic naphtha, and jet fuel, the method comprising:
 a. hydrotreating a renewable feedstock with a diluent to produce a hydrotreated heavy fraction and a light fraction.   b. hydroisomerizing the hydrotreated heavy fraction to produce a hydroisomerized heavy fraction and isoparaffin.   c. recycling the hydroisomerized heavy fraction to step (b) and hydroisomerizing the hydroisomerized heavy fraction to produce an isoparaffinic product; and,   d. fractionating the isoparaffinic product and the light fraction to produce liquid petroleum gases, isoparaffinic naphtha, and jet fuel; and wherein the diluent comprises C3-C18 n-paraffins and/or iso-paraffins produced by at least one of the steps of the method.   
     
     
         12 . The method of  claim 11 , wherein the liquid petroleum gases comprise propane, iso-butane, and n-butane. 
     
     
         13 . The method of  claim 11  wherein the renewable feedstock comprises triglycerides, free fatty acids and combinations thereof. 
     
     
         14 . The method of  claim 11  wherein the renewable feedstock is selected from the group comprising of animal fats, animal oils, vegetable fats, vegetable oils, rendered fats, restaurant grease, waste industrial frying oils, fish oils, and combinations thereof. 
     
     
         15 . The method of  claim 11 , wherein the hydrotreating step operating conditions comprise a reaction temperature of from about 300° F. to about 850° F. and a reaction pressure of from about 250 psig to about 3000 psig. 
     
     
         16 . The method of  claim 11  wherein the liquid hourly space velocity through the hydrotreating step is about 0.5 to about 5.0 
     
     
         17 . The method of  claim 11 , wherein the hydroisomerizing step operating conditions comprise a reaction temperature of from about 300° F. to about 850° F. and a reaction pressure of from about 250 psig to about 3000 psig. 
     
     
         18 . The method of  claim 11  wherein the hydrotreating step is carried out in the presence of a sulfided bimetallic catalyst. 
     
     
         19 . The method according to  claim 18  wherein the catalyst is a supported NiW, NiMo or a CoMo catalyst, the support being alumina. 
     
     
         20 . The method of  claim 1 , wherein the isoparaffinic product has a boiling point range of from about 150° C. to about 300° C.