Methods and systems for processing cellulosic biomass

Abstract

Separation of a product of digestion of cellulosic biomass solids may be challenging due to the various components contained therein. Methods and systems for processing cellulosic biomass, particularly a reaction product of a hydrothermal reaction containing lignin-derived products, such as phenolics, comprise providing the reaction product to a separation zone comprising a liquid-liquid extraction unit. The liquid-liquid extraction unit can provide an aqueous portion and a non-aqueous portion, where these portions can be separated into various fractions individually. For example, desirable compounds in the aqueous portion and non-aqueous portion can be recovered from the portions individually and optionally combined to be further processed into a fuels product. Heavier components in the aqueous portion and non-aqueous portion can be recovered from the portions individually and used in the process, such as phenolics that can be used as a digestion solvent.

1 . A method comprising:
 (a) heating cellulosic biomass solids, molecular hydrogen, a catalyst capable of activating molecular hydrogen, and a digestion solvent in a reactor in a first reaction zone to produce a first reaction product;   (b) providing a first extraction solvent and at least a portion of the first reaction product to a first liquid-liquid extraction unit in a separation zone to recover a first aqueous stream and a first non-aqueous stream, wherein the first aqueous stream comprises a major portion of water in said portion of the first reaction product;   (c) providing the first aqueous stream and a second extraction solvent to a second liquid-liquid extraction unit in the separation zone to recover a second aqueous stream and a second non-aqueous stream;   (d) optionally providing at least a portion of the first reaction product to a gas separator unit to recover a vapor fraction comprising compounds with a normal boiling point of 100 degrees C. or lower before providing the first reaction product to the separation zone;   (e) providing the first and second non-aqueous streams to a distillation unit to recover a distillate overhead fraction, a distillate middle fraction, and a distillate bottom fraction;   (f) providing at least a portion of the distillate middle fraction to the first liquid-liquid extraction unit, wherein the first extraction solvent comprises said portion of the distillate middle fraction;   (g) providing to a further processing zone at least one of at least a portion of the vapor fraction and at least a portion of the distillate overhead fraction to generate a higher hydrocarbon product;   (h) providing at least a portion of the higher hydrocarbon product to the second liquid-liquid extraction unit, wherein the second extraction solvent comprises said portion of the higher hydrocarbon product.   
     
     
         2 . The method of  claim 1  further comprising:
 providing the aqueous stream to an aqueous stream separation zone to recover a light compounds from at least a portion of the aqueous phase in an overhead fraction, wherein the overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream. 
 
     
     
         3 . The method of  claim 2  wherein the aqueous stream separation zone comprises a first flasher and a second flasher, wherein the method further comprises:
 providing the aqueous stream to the first flasher to recover a first overhead fraction and a first bottom fraction; 
 providing the first bottom fraction to the second flasher to recover middle-boiling compounds in a second overhead fraction and a second bottom fraction, 
 wherein the first overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream, and 
 wherein the second overhead fraction comprises compounds with a normal boiling point of 150 degrees C. or higher. 
 
     
     
         4 . The method of  claim 1  further comprising:
 flashing at least one of the first non-aqueous stream and the second non-aqueous stream to recover an overhead fraction and a bottom fraction, wherein the overhead fraction from flashing of the respective non-aqueous stream(s) comprises compounds with a normal boiling point of less than 150 degrees C. before providing the respective non-aqueous stream(s) to the distillation unit. 
 
     
     
         5 . The method of  claim 4  further comprising:
 providing a first portion of the bottom fraction from flashing of the respective aqueous stream(s) to the first liquid-liquid extraction unit, wherein the first extraction solvent comprises said first portion of the bottom fraction from flashing of the respective aqueous stream(s). 
 
     
     
         6 . The method of  claim 1  further comprising:
 at least partially depolymerizing lignin in the non-aqueous stream by providing at least a portion of the non-aqueous stream to a lignin depolymerization unit before providing it to the distillation unit. 
 
     
     
         7 . The method of  claim 1  further comprising:
 providing at least a portion of the middle fraction from the distillation unit to the reactor in the first reaction zone. 
 
     
     
         8 . The method of  claim 1  wherein the middle fraction comprises at least one of a cyclic alcohol and a phenol. 
     
     
         9 . The method of  claim 8  wherein the cyclic alcohol can comprise at least one of cyclohexanols, alkyl cyclohexanols, cyclopentanols, and alkyl cyclopentanols. 
     
     
         10 . The method of  claim 1  further comprising:
 subjecting the first reaction products to a base catalyzed depolymerization reaction prior to providing the respective reaction product to the separation zone. 
 
     
     
         11 . The method of  claim 1  further comprising:
 providing an acid solution to the first reaction products prior to providing the reaction product to the separation zone. 
 
     
     
         12 . A method comprising:
 (a) heating cellulosic biomass solids, molecular hydrogen, a catalyst capable of activating molecular hydrogen, and a digestion solvent in a reactor in a first reaction zone to produce a first reaction product;   (b) heating at least a portion of the first reaction product, molecular hydrogen, and a catalyst capable of activating molecular hydrogen in a reactor in a second reaction zone to produce a second reaction product;   (c) providing a first extraction solvent and at least a portion of the second reaction product to a first liquid-liquid extraction unit in a separation zone to recover a first aqueous stream and a first non-aqueous stream, wherein the first aqueous stream comprises a major portion of water in said portion of the first reaction product;   (d) providing the first aqueous stream and a second extraction solvent to a second liquid-liquid extraction unit in the separation zone to recover a second aqueous stream and a second non-aqueous stream;   (e) optionally providing at least a portion of the second reaction product to a gas separator unit to recover a vapor fraction comprising compounds with a normal boiling point of 100 degrees C. or lower before providing the second reaction product to the separation zone;   (f) providing the first and second non-aqueous streams to a distillation unit to recover a distillate overhead fraction, a distillate middle fraction, and a distillate bottom fraction;   (g) providing at least a portion of the distillate middle fraction to the first liquid-liquid extraction unit, wherein the first extraction solvent comprises said portion of the distillate middle fraction;   (h) providing to a further processing zone at least one of at least a portion of the vapor fraction and at least a portion of the distillate overhead fraction to provide a higher hydrocarbon product;   (i) providing at least a portion of the higher hydrocarbon product to the second liquid-liquid extraction unit, wherein the second extraction solvent comprises said portion of the higher hydrocarbon product.   
     
     
         13 . The method of  claim 12  further comprising:
 providing the aqueous stream to an aqueous stream separation zone to recover a light compounds from at least a portion of the aqueous phase in an overhead fraction, wherein the overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream. 
 
     
     
         14 . The method of  claim 13  wherein the aqueous stream separation zone comprises a first flasher and a second flasher, wherein the method further comprises:
 providing the aqueous stream to the first flasher to recover a first overhead fraction and a first bottom fraction; 
 providing the first bottom fraction to the second flasher to recover middle-boiling compounds in a second overhead fraction and a second bottom fraction, 
 wherein the first overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream, and 
 wherein the second overhead fraction comprises compounds with a normal boiling point of 150 degrees C. or higher. 
 
     
     
         15 . The method of  claim 13  further comprising:
 flashing at least one of the first non-aqueous stream and the second non-aqueous stream to recover an overhead fraction and a bottom fraction, wherein the overhead fraction from flashing of the respective non-aqueous stream(s) comprises compounds with a normal boiling point of less than 150 degrees C. before providing the respective non-aqueous stream(s) to the distillation unit; and 
 providing a first portion of the bottom fraction from flashing of the respective aqueous stream(s) to the first liquid-liquid extraction unit, wherein the first extraction solvent comprises said first portion of the bottom fraction from flashing of the respective aqueous stream(s). 
 
     
     
         16 . The method of  claim 12  wherein the middle fraction comprises at least one of a cyclic alcohol and a phenol. 
     
     
         17 . The method of  claim 16  wherein the cyclic alcohol can comprise at least one of cyclohexanols, alkyl cyclohexanols, cyclopentanols, and alkyl cyclopentanols. 
     
     
         18 . The method of  claim 12  further comprising:
 subjecting at least one of the first and second reaction products to a base catalyzed depolymerization reaction prior to providing the respective reaction product to the separation zone. 
 
     
     
         19 . The method of  claim 12  further comprising:
 providing an acid solution to at least one of the first and second reaction products prior to providing the respective reaction product to the separation zone. 
 
     
     
         20 . A system comprising:
 a first reaction zone comprising a reactor configured heat cellulosic biomass solids, molecular hydrogen, a catalyst capable of activating molecular hydrogen, and a digestion solvent to form a first reaction product;   a separation zone comprising:
 a first liquid-liquid extraction unit having an inlet in fluid communication with an outlet of the reactor in the first reaction zone to receive the first reaction product, wherein the first liquid-liquid extraction unit is configured to provide a first aqueous stream and a first non-aqueous stream, wherein the first aqueous stream comprises a major portion of water in the first reaction product in the first liquid-liquid extraction unit; and 
 a second liquid-liquid phase extraction unit having an inlet in fluid communication with an outlet of the first liquid-liquid extraction unit to receive the first aqueous phase, wherein the second liquid-liquid extraction unit is configured to provide a second aqueous stream and a second non-aqueous stream, wherein the second aqueous stream comprises a major portion of water in the first aqueous stream in the second liquid-liquid extraction unit; 
 a distillation unit having an inlet in fluid communication with an outlet of the first and second liquid-liquid extraction units to receive at least a portion of the first and second non-aqueous streams, wherein the distillation unit is configured to provide at least a distillate overhead fraction, a distillate middle fraction, and a distillate bottom fraction, wherein the distillation unit is in fluid communication with an inlet of the first liquid-liquid extraction unit to provide at least a portion of the distillate middle fraction; 
   an optional gas separator unit having an inlet in fluid communication with the reactor the first reaction zone to receive the first reaction product, wherein the gas separator unit is configured to remove a vapor fraction comprising compounds having a normal boiling point of 100 degrees C. or less from the first reaction product, wherein the optional gas separator unit further comprises an outlet in fluid communication with the first liquid-liquid extraction unit to provide the first reaction product without the vapor fraction; and   a further processing zone comprising a further processing unit having an inlet in fluid communication with an outlet of at least one of (i) the separation zone to receive at least a portion of the overhead fraction from the distillation unit and (ii) the optional gas separator unit to receive at least a portion of the vapor fraction, wherein the further processing zone is configured to provide a higher hydrocarbon product; wherein the further processing unit is in fluid communication with an inlet of the second liquid-liquid extraction unit to provide at least a portion of the higher hydrocarbon product.   
     
     
         21 . The system of  claim 20  further comprising:
 a lignin depolymerization unit in fluid communication with an outlet of the liquid-liquid extraction unit to receive at least a portion of the non-aqueous stream, wherein the lignin depolymerization unit is configured to provide at least partial depolymerization of lignin in the non-aqueous stream, 
 wherein an outlet of the lignin depolymerization unit is in fluid communication with the distillation unit to provide the non-aqueous stream with at least partial lignin depolymerization. 
 
     
     
         22 . The system of  claim 20  wherein the separation zone further comprises:
 an aqueous stream separation zone in fluid communication with an outlet of the liquid-liquid extraction unit to receive at least a portion of the aqueous stream, wherein the aqueous stream separation zone is configured to provide an overhead fraction and a bottom fraction, wherein the overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream. 
 
     
     
         23 . The system of  claim 22  wherein the aqueous stream separation zone comprises:
 a first flasher configured to produce a first overhead fraction and a first bottom fraction, wherein the first overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream, and 
 wherein the second overhead fraction comprises compounds with a normal boiling point of 150 degrees C. or higher; 
 wherein the first flasher comprises an outlet in fluid communication with an inlet of a second flasher to provide the first bottom fraction to the second flasher. 
 
     
     
         24 . The system of  claim 20  further comprising:
 a non-aqueous stream flasher having an inlet in fluid communication with an outlet of the first liquid-liquid extraction units to receive the non-aqueous stream, wherein the non-aqueous stream flasher is configured to recover an overhead fraction and a bottom fraction, wherein the overhead fraction from flashing of the non-aqueous stream comprises compounds with a normal boiling point of less than 150 degrees C., wherein the non-aqueous stream flasher comprises an outlet in fluid communication with the distillation unit to provide at least a portion of the bottom fraction from flashing of the aqueous stream to the distillation unit. 
 
     
     
         25 . The system of  claim 20  wherein the non-aqueous stream flasher further comprises an outlet in fluid communication with the first liquid-liquid extraction unit to provide at least a portion of the bottom fraction from flashing of the aqueous stream to the first liquid-liquid extraction unit. 
     
     
         26 . The system of  claim 20  further comprising:
 a lignin removal mechanism having an inlet in fluid communication with an outlet of the lignin depolymerization unit to receive the non-aqueous stream with at least partial lignin depolymeriztion; wherein the lignin removal mechanism is configured to remove at least a portion of the lignin in the non-aqueous stream; 
 wherein the lignin removal mechanism has an outlet in fluid communication with the distillation unit to provide the non-aqueous stream from the lignin removal mechanism; and 
 wherein the lignin removal mechanism has an outlet in fluid communication with an inlet of the lignin removal mechanism to recycle the non-aqueous stream. 
 
     
     
         27 . The system of  claim 20  wherein the distillation unit comprises:
 an outlet in fluid communication with an inlet of the reactor in the first reaction zone to provide at least a portion of the middle fraction. 
 
     
     
         28 . The system of  claim 20  wherein an outlet of the second liquid-liquid extraction unit is in fluid communication with an inlet of the reactor in the first reaction zone to provide a second portion of the second aqueous phase thereto. 
     
     
         29 . A system comprising:
 a first reaction zone comprising a reactor configured heat cellulosic biomass solids, molecular hydrogen, a catalyst capable of activating molecular hydrogen, and a digestion solvent to form a first reaction product;   a second reaction zone comprising a reactor in fluid communication with an outlet of the reactor in the first reaction zone to receive the first reaction product, wherein the reactor in the second reaction zone is configured to heat a second reaction content comprising the first reaction product, molecular hydrogen, and a catalyst capable of activating molecular hydrogen to form a second reaction product;   a separation zone comprising:
 a first liquid-liquid extraction unit having an inlet in fluid communication with an outlet of the reactor in the second reaction zone to receive the second reaction product, wherein the first liquid-liquid extraction unit is configured to provide a first aqueous stream and a first non-aqueous stream, wherein the first aqueous stream comprises a major portion of water in the second reaction product in the first liquid-liquid extraction unit; and 
 a second liquid-liquid phase extraction unit having an inlet in fluid communication with an outlet of the first liquid-liquid extraction unit to receive the first aqueous phase, wherein the second liquid-liquid extraction unit is configured to provide a second aqueous stream and a second non-aqueous stream, wherein the second aqueous stream comprises a major portion of water in the first aqueous stream in the second liquid-liquid extraction unit; 
 a distillation unit having an inlet in fluid communication with an outlet of the first and second liquid-liquid extraction units to receive at least a portion of the first and second non-aqueous streams, wherein the distillation unit is configured to provide at least a distillate overhead fraction, a distillate middle fraction, and a distillate bottom fraction, wherein the distillation unit is in fluid communication with an inlet of the first liquid-liquid extraction unit to provide at least a portion of the distillate middle fraction; 
   an optional gas separator unit having an inlet in fluid communication with the reactor the second reaction zone to receive the second reaction product, wherein the gas separator unit is configured to remove a vapor fraction comprising compounds having a normal boiling point of 100 degrees C. or less from the second reaction product, wherein the optional gas separator unit further comprises an outlet in fluid communication with the first liquid-liquid extraction unit to provide the second reaction product without the vapor fraction; and   a further processing zone comprising a further processing unit having an inlet in fluid communication with an outlet of at least one of (i) the separation zone to receive at least a portion of the overhead fraction from the distillation unit and (ii) the optional gas separator unit to receive at least a portion of the vapor fraction, wherein the further processing zone is configured to provide a higher hydrocarbon product; wherein the further processing unit is in fluid communication with an inlet of the second liquid-liquid extraction unit to provide at least a portion of the higher hydrocarbon product.   
     
     
         30 . The system of  claim 29  wherein the separation zone further comprises:
 an aqueous stream separation zone in fluid communication with an outlet of the liquid-liquid extraction unit to receive at least a portion of the aqueous stream, wherein the aqueous stream separation zone is configured to provide an overhead fraction and a bottom fraction, wherein the overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream. 
 
     
     
         31 . The system of  claim 30  wherein the aqueous stream separation zone comprises:
 a first flasher configured to produce a first overhead fraction and a first bottom fraction, wherein the first overhead fraction comprises a major portion of compounds with a normal boiling point of less than 150 degrees C. in said portion of the aqueous stream, and 
 wherein the second overhead fraction comprises compounds with a normal boiling point of 150 degrees C. or higher; 
 wherein the first flasher comprises an outlet in fluid communication with an inlet of a second flasher to provide the first bottom fraction to the second flasher 
 
     
     
         32 . The system of  claim 29  further comprising:
 a non-aqueous stream flasher having an inlet in fluid communication with an outlet of at least one of the first and second liquid-liquid extraction units to receive the respective non-aqueous stream(s), wherein the non-aqueous stream flasher is configured to recover an overhead fraction and a bottom fraction, wherein the overhead fraction from flashing of the respective non-aqueous stream(s) comprises compounds with a normal boiling point of less than 150 degrees C., wherein the non-aqueous stream flasher comprises an outlet in fluid communication with the distillation unit to provide at least a portion of the bottom fraction from flashing of the respective aqueous stream(s) to the distillation unit. 
 
     
     
         33 . The system of  claim 29  wherein the distillation unit comprises:
 an outlet in fluid communication with an inlet of the reactor in the first reaction zone to provide at least a portion of the middle fraction; and 
 an outlet in fluid communication with an inlet of the reactor in the second reaction zone to provide at least a portion of the middle fraction.