Co-production of biofuels and glycols

Abstract

Methods and systems for co-producing higher hydrocarbons and glycols from bio-based feedstocks containing carbohydrates are disclosed.

We claim: 
     
         1 . A method comprising:
 (i) providing a bio-based feedstock stream containing carbohydrates and water;   (ii) contacting, in a first reaction system, the bio-based feedstock stream with an aqueous phase reforming catalyst at a temperature in the range of 120° C. to 280° C. and 0.1 to 150 bar of hydrogen to form a first intermediate stream containing plurality of oxygenated intermediates comprising at least 5 wt %, based on the total oxygenates content, of glycols that comprises ethylene glycol (EG) and 1,2-propylene glycol (PG), and other monooxygenates;   (iii) contacting, in a second reaction system, at least a first portion of said first intermediate stream in the presence of a aqueous phase reforming catalyst at a temperature in the range of 160° C. to 280° C. to produce a second intermediate stream containing plurality of oxygenated intermediates stream and hydrogen;   (iv) providing at least a portion of said hydrogen to the first reaction system;   (v) processing at least a portion of the second intermediate stream to form a liquid fuel;   (vi) providing a second portion of said first intermediate stream to a first separation system;   (vii) separating a portion of said first intermediate stream, in the first separation system, to a monooxygenates stream comprising monooxygenates and a glycol rich stream comprising at least 10 wt %, based on the total oxygenates, of glycols by flashing;   (viii) recovering glycols from the glycol rich stream; and   (ix) recycling at least a portion of said monooxygenates stream to the first reaction system.   
     
     
         2 . The method of  claim 1  wherein glycols are recovered by separating finished glycol from the glycol rich stream. 
     
     
         3 . The method of  claim 1  wherein the glycol content of the first intermediate stream produced in step (ii) is at least 25 wt %, based on the total oxygenates content. 
     
     
         4 . The method of  claim 1  wherein the ratio of the first intermediate stream provided to the first separation system and to the second reaction system is in the range of 1.5:1 to 10:1. 
     
     
         5 . The method of  claim 1  wherein the maximum steady state temperature of the first reaction system is at least 10° C. less than the maximum steady state temperature of the second reaction system; 
     
     
         6 . The method of  claim 5  wherein no process heat from external source is added between the first and second reaction systems, or to the second reaction system, wherein the temperature increase in the second reaction system results from the exothermic heats from the first reaction system and the second reaction system. 
     
     
         7 . The method of  claim 3  wherein the glycol rich stream in step (vii) comprises at least 25 wt %, based on the total oxygenates, of glycols. 
     
     
         8 . The method of  claim 1  wherein a bio-based feedstock is subjected to a digestive solvent to provide bio-based feedstock stream comprising carbohydrates and water. 
     
     
         9 . The method of  claim 1  wherein the conversion of carbohydrate or sugar alcohol in the first reaction system is limited to less than 80%. 
     
     
         10 . The method of  claim 9  wherein the conversion of carbohydrate or sugar alcohol in the first reaction system is limited to less than 70%. 
     
     
         11 . The method of  claim 10  wherein the conversion of carbohydrate or sugar alcohols in the first reaction system is limited to less than 60%. 
     
     
         12 . The method of  claim 11  wherein the conversion of carbohydrate or sugar alcohols in the first reaction system is limited to less than 50%, 
     
     
         13 . The method of  claim 1  wherein the conversion of carbohydrates and sugar alcohols to monooxygenated compounds across the first reaction system and the second reaction system is less than 90%; 
     
     
         14 . The method of  claim 13  wherein the second intermediate stream from the second reaction system is flash distilled to provide a stream containing at least a portion of monooxygenate intermediates as feed for production of liquid fuels. 
     
     
         15 . The method of  claim 14  wherein the bottoms from flashing containing enriched concentrations of unconverted carbohydrates, sugar alcohols, glycols, and some monooxygenates, are recycle to the first reaction system. 
     
     
         16 . A method comprising:
 (i) providing a bio-based feedstock stream containing carbohydrates and water;   (ii) contacting, in a first reaction zone, the bio-based feedstock stream with an aqueous phase reforming catalyst at a temperature in the range of 120° C. to 280° C. and 0.1 to 150 bar of hydrogen to produce a first intermediate stream containing plurality of oxygenated intermediates comprising at least 5 wt %, based on the total oxygenates content, of glycols that comprises ethylene glycol (EG) and 1,2-propylene glycol (PG), and other monooxygenates;   (iii) contacting, in a second reaction zone, at least a first portion of said first intermediate stream in the presence of a aqueous phase reforming catalyst at a temperature in the range of 160° C. to 280° C. to produce a combined glycol and oxygenated intermediate stream comprising greater than 5 wt % glycols, based on the total oxygenates and hydrocarbons;   (iv) separating, by flashing, the combined glycol and oxygenated intermediate stream into a glycol rich stream comprising at least 10 wt %, based on the total oxygenates, of glycols, and a mono-oxygenates-rich stream;   (v) processing at least a portion of the monooxygenates-rich stream to form a liquid fuel;   (vi) recovering glycols from the glycol rich stream; and   (vii) recycling at least a portion of either or both of the glycol-rich stream or mono-oxygenates rich stream to provide solvent for the first reaction zone.   
     
     
         17 . The method of  claim 16  where the recycled solvent is routed to a digestion zone to digest solid biomass to provide feed for the first reaction zone. 
     
     
         18 . The method of  claim 16  wherein glycols are recovered by separating from the glycol rich stream glycols and remaining oxygenates stream; (vii) further contacting, in a third reaction system, at least a portion of said remaining oxygenates stream in the presence of a aqueous phase reforming catalyst at a temperature in the range of 160° C. to 280° C. to produce a recycle oxygenates stream and hydrogen; and (viii) providing at least a portion of said recycle oxygenates stream and a portion of said hydrogen to the first reaction zone. 
     
     
         19 . The method of  claim 16  wherein the glycol content of the first intermediate stream produced in step (ii) is at least 25 wt %, based on the total oxygenates content. 
     
     
         20 . The method of  claim 16  wherein the ratio of the first intermediate stream provided to the first separation system and to the second reaction system is in the range of 1.5:1 to 10:1.