Low energy production of alcohols and gasoline blends with mixed higher alcohols

Abstract

A method of producing a mixed higher alcohol blend is disclosed which may be self contained both composition-wise with regard to the specific alcohols as well as energy-wise. In one embodiment, the energy created during an exothermic Fischer-Tropsch reaction is utilized to drive downstream distillation column reboilers in a cascade mechanism, thereby providing a low energy process. In one embodiment, an extraction process is performed utilizing a suitable solvent and the co-solvent capabilities of the C4+ higher alcohols already present in the aqueous alcohol stream provided to the extraction column.

What is claimed is: 
     
         1 . A method of producing a mixed higher alcohol blend comprising:
 providing an aqueous alcohol stream including mixed lower and higher alcohols;   removing the lower alcohols from the aqueous alcohol stream, resulting in a total weight of C4+ alcohols greater than or equal to a total weight of C3 alcohols in the resultant aqueous alcohol stream;   extracting the C3+ higher alcohols from the resultant alcohol stream with a solvent.   
     
     
         2 . The method of  claim 1 , wherein providing an aqueous alcohol stream comprises passing a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide through a catalytic zone. 
     
     
         3 . The method of  claim 2 , further comprising a catalyst comprising Cr, La, Al, Cu, Co and Na. 
     
     
         4 . The method of  claim 2 , further comprising a catalyst comprising Cu, Co, Cr and K. 
     
     
         5 . The method of  claim 1 , wherein removing the lower alcohols from the aqueous alcohol stream results in at least a 1:1.4 weight ratio of C3 to C4+ alcohols in the resultant aqueous alcohol stream. 
     
     
         6 . The method of  claim 1 , wherein removing the lower alcohols from the aqueous alcohol stream comprises providing the aqueous alcohol stream to a distillation column. 
     
     
         7 . The method of  claim 6 , wherein removing the lower alcohols from the aqueous alcohol stream further comprises removing iso-propanol from the aqueous alcohol stream. 
     
     
         8 . The method of  claim 6 , further comprising providing an overhead product stream including methanol, ethanol and water associated with the ethanol azeotrope from the distillation column to a second distillation column to separate the methanol. 
     
     
         9 . The method of  claim 6 , further comprising providing a bottoms product including C3+ alcohols and water from the distillation column to an extraction column. 
     
     
         10 . The method of  claim 9 , further comprising providing a solvent to the extraction column. 
     
     
         11 . The method of  claim 10 , wherein the solvent is gasoline. 
     
     
         12 . The method of  claim 10 , further comprising operating the extraction column counter-currently. 
     
     
         13 . The method of  claim 8 , wherein energy generated from passing a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide through a catalytic zone is used to provide energy to a reboiler for driving the distillation column. 
     
     
         14 . The method of  claim 13 , wherein energy from the overhead product stream from the distillation column is used to provide energy to a second reboiler for driving the second distillation column. 
     
     
         15 . The method of  claim 14 , wherein no additional energy is required to drive the distillation column, or the second distillation column. 
     
     
         16 . The method of  claim 10 , further comprising distilling the extract exiting the top of the extraction column in a third distillation column to separate the C3+ higher alcohols from the solvent. 
     
     
         17 . The method of  claim 16 , wherein energy generated from passing a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide through a catalytic zone is used to provide energy to a third reboiler for driving the third distillation column. 
     
     
         18 . The method of  claim 17 , wherein energy from the overhead product stream from the third distillation column is used to provide energy to a reboiler for the distillation column. 
     
     
         19 . The method of  claim 18 , wherein energy from the overhead product stream from the distillation column is used to provide energy to a second reboiler for a second distillation column. 
     
     
         20 . The method of  claim 19 , wherein no additional energy is required to drive the distillation column, the second distillation column, and the third distillation column.