Process for producing diesel fuel and jet fuel from biorenewable feedstocks

Abstract

A process has been developed for producing diesel fuel or jet fuel from renewable feedstocks such as fats and oils from plants and animals. The process involves producing a hydrogen-rich mixture in a reformer, hydrolyzing a renewable feedstock to produce a free fatty acid stream and a glycerol-containing stream, catalytically treating the free fatty acid stream by hydrogenating and deoxygenating to provide a hydrocarbon fraction useful as a diesel fuel or jet fuel. A selective separation such as a hot high pressure hydrogen stripper may be used to remove at least the carbon oxides from the reaction zone effluent and provide a liquid recycle stream at pressure and temperature. A vapor stream is separated from the effluent and at least carbon dioxide is removed using at least one amine absorber. The resulting hydrogen-rich stream is recycled to the reaction zone.

The invention claimed is: 
     
         1 . A process for producing a paraffin-rich hydrocarbon fuel from a renewable feedstock comprising:
 a) producing a hydrogen-rich mixture in a steam fuel reformer;   b) supplying the hydrogen-rich mixture without hydrogen purification as a source of hydrogen to a reaction zone;   c) treating the feedstock in the reaction zone by hydrogenating and deoxygenating the feedstock using at least one catalyst at reaction conditions in the presence of hydrogen to provide a reaction zone product stream comprising hydrogen, carbon dioxide, water, and a hydrocarbon fraction comprising paraffins;   d) separating the reaction zone product stream into at least:   i. a gaseous component comprising at least hydrogen, and carbon dioxide;   ii. a hydrocarbon component comprising paraffins;   e) selectively separating the gaseous component to produce at least a stream containing at least hydrogen and depleted in carbon dioxide; and   f) recycling the stream containing at least hydrogen and depleted in carbon dioxide to the reaction zone.   
     
     
         2 . The process of  claim 1  further comprising passing the hydrogen-rich mixture through a water gas shift reactor to convert at least a portion of carbon monoxide to carbon dioxide and hydrogen. 
     
     
         3 . The process of  claim 1  further comprising isomerizing the deoxygenation reaction product by contacting it with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the n-paraffins to iso-parafins. 
     
     
         4 . The process in  claim 1  wherein a water gas shift reaction is carried out in presence of water vapor in the reaction zone to convert at least a portion of carbon monoxide to carbon dioxide. 
     
     
         5 . The process of  claim 1  further comprising recycling a portion of the hydrocarbon component comprising parafins to the reaction zone. 
     
     
         6 . The process of  claim 1  wherein the reaction zone contains at least one sulfur containing component. 
     
     
         7 . The process of  claim 1  wherein the selective separating step uses at least one amine absorber zone. 
     
     
         8 . A process for producing a paraffin-rich hydrocarbon fuel from a renewable feedstock comprising:
 a) producing a hydrogen-rich mixture in a steam fuel reformer;   b) supplying the hydrogen-rich mixture without hydrogen purification as a source of hydrogen to a reaction zone;   c) hydrolyzing the renewable feedstock to produce a free fatty acid stream and a glycerol-containing water stream;   d) treating the free fatty acid stream in the reaction zone by hydrogenating and deoxygenating the free fatty acid stream using at least one catalyst at reaction conditions in the presence of hydrogen to provide a reaction zone product stream comprising hydrogen, carbon dioxide, water, and a hydrocarbon fraction comprising paraffins;   e) separating the reaction zone product stream into at least:   i. a gaseous component comprising at least hydrogen, and carbon dioxide;   ii. a hydrocarbon component comprising parafins;   f) selectively separating the gaseous component to produce at least a stream containing at least hydrogen and depleted in carbon dioxide; and   g) recycling the stream containing at least hydrogen and depleted in carbon dioxide to the reaction zone.   
     
     
         9 . The process of  claim 8  further comprising isomerizing the deoxygenation reaction product by contacting it with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the n-paraffins to iso-parafins. 
     
     
         10 . The process in  claim 8  wherein a water gas shift reaction is carried out in presence of water vapor in the reaction zone to convert at least a portion of carbon monoxide to carbon dioxide. 
     
     
         11 . The process of  claim 8  further comprising recycling a portion of the hydrocarbon component comprising parafins to the reaction zone. 
     
     
         12 . The process of  claim 8  wherein the reaction zone contains at least one sulfur containing component. 
     
     
         13 . The process of  claim 8  wherein the selective separating step uses at least one amine absorber zone. 
     
     
         14 . The process of  claim 8  further comprising passing the hydrogen-rich mixture through a water gas shift reactor to convert at least a portion of carbon monoxide to carbon dioxide and hydrogen. 
     
     
         15 . A process for producing a paraffin-rich diesel boiling range product from a renewable feedstock comprising:
 a) producing a hydrogen-rich mixture in a steam fuel reformer;   b) supplying the hydrogen-rich mixture without hydrogen purification to a hot high pressure hydrogen stripper;   c) hydrolyzing the renewable feedstock to produce a free fatty acid stream and a glycerol-containing water stream;   d) treating the free fatty acid stream in a reaction zone by hydrogenating and deoxygenating the free fatty acid stream using at least one catalyst at reaction conditions in the presence of hydrogen and at least one sulfur containing component to provide a reaction zone product stream comprising hydrogen, hydrogen sulfide, carbon dioxide, water, and a hydrocarbon fraction comprising paraffins useful as a diesel boiling range fuel;   f) selectively separating, in the hot high pressure hydrogen stripper, the reaction zone product stream into a gaseous stream comprising hydrogen, hydrogen sulfide and at least a portion of the water and carbon oxides from the reaction zone product stream and a remainder stream comprising at least the paraffins;   f) separating:   1) a gaseous component comprising at least hydrogen, hydrogen sulfide, water, and carbon dioxide;   2) a hydrocarbon component; and   3) a water component;   g) recycling a portion of the remainder stream comprising at least the paraffins or a portion of the hydrocarbon component to the reaction zone;   h) selectively separating the gaseous component using at least one amine absorber zone to produce at least a stream containing at least hydrogen and depleted in carbon dioxide; and   i) recycling the stream containing at least hydrogen and depleted in carbon dioxide to the reaction zone.   
     
     
         16 . The process in  claim 15  further comprising passing the hydrogen-rich mixture through a water gas shift reactor to convert at least a portion of carbon monoxide to carbon dioxide and hydrogen before the hydrogen-rich mixture is routed to the hot high pressure hydrogen stripper. 
     
     
         17 . The process in  claim 15  wherein a water gas shift reaction is carried out in presence of water vapor in the reaction zone to convert at least a portion of carbon monoxide to carbon dioxide. 
     
     
         18 . The process in  claim 15  further comprising isomerizing the deoxygenation reaction product by contacting it with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the n-paraffins to iso-parafins. 
     
     
         19 . The process in  claim 15  further comprising separating glycerol from the glycerol-containing water stream and using the glycerol as the hydrogen honor fuel in the steam fuel reformer. 
     
     
         20 . The process in  claim 15  further comprising separating glycerol from the glycerol-containing water stream and using the glycerol in a combustion process to provide heat for the steam fuel reformer.