Hydropyrolysis of biomass for producing high quality liquid fuels

Abstract

A self-sustaining process for producing liquid fuels from biomass in which the biomass is hydropyrolyzed in a reactor vessel containing molecular hydrogen and a deoxygenating catalyst, producing a partially deoxygenated pyrolysis liquid, which is hydrogenated using a hydroconversion catalyst, producing a substantially fully deoxygenated pyrolysis liquid and a gaseous mixture comprising CO and light hydrocarbon gases (C 1 -C 4 ). The gaseous mixture is reformed in a steam reformer, producing reformed molecular hydrogen, which is then introduced into the reactor vessel for hydropyrolizing the biomass. The deoxygenated liquid product is further processed to produce diesel fuel and gasoline.

1 . A process for producing liquid products from biomass comprising the steps of:
 a) introducing biomass and reformed molecular hydrogen into a hydropyrolysis reactor vessel containing a deoxygenating catalyst and hydropyrolyzing said biomass, producing CO 2 , CO and C 1 -C 4  gas, a partially deoxygenated pyrolysis liquid, char, and first stage heat;   b) removing said char from said partially deoxygenated pyrolysis liquid;   c) hydroconverting said partially deoxygenated pyrolysis liquid in a hydroconversion reactor vessel using a hydroconversion catalyst in the presence of the CO 2 , CO and C 1 -C 4  gas generated in step a), producing a substantially fully deoxygenated pyrolysis liquid, a gaseous mixture comprising CO, CO 2 , and light hydrocarbon gases (C 1 -C 4 ), and second stage heat;   d) steam reforming a portion of said gaseous mixture using water produced in step a) and step c), producing said reformed molecular hydrogen, wherein steps a) and c) are operated at conditions under which about 40-60% of oxygen in said biomass is converted to H 2 O and about 40-60% of said oxygen is converted to CO and CO 2 ; and   e) recycling a portion of said liquid product created in step c) to said hydropyrolysis reactor vessel or said hydroconversion reactor vessel to control temperature therein.   
     
     
         2 . The process of  claim 1 , wherein said hydroconversion catalyst catalyzes both a water-gas-shift reaction and hydroconversion. 
     
     
         3 . The process of  claim 1 , wherein all of said steps a), c), and d) are carried out at a substantially same pressure. 
     
     
         4 . The process of  claim 3 , wherein said pressure is in a range of about 300 to about 800 psig. 
     
     
         5 . The process of  claim 4 , wherein said hydropyrolysis is carried out at a temperature in a range of about 800° F. to about 950° F. and said hydroconversion is carried out at a temperature in a range of about 600° F. to about 800° F. 
     
     
         6 . The process of  claim 1 , wherein said hydroconversion is carried out with a liquid hourly space velocity in a range of about 0.3 to about 0.7. 
     
     
         7 . The process of  claim 1 , wherein said substantially fully deoxygenated pyrolysis liquid is separated into diesel and gasoline fractions suitable for use as transportation fuel. 
     
     
         8 . The process of  claim 1 , wherein said hydropyrolysis reactor vessel is a fluidized bed reactor containing a fluidized bed and a gas residence time in said hydropyrolysis reactor vessel is less than about one minute. 
     
     
         9 . The process of  claim 8 , wherein said char is removed from said fluidized bed reactor substantially only from above said fluidized bed. 
     
     
         10 . The process of  claim 1 , wherein char is removed from said partially deoxygenated pyrolysis liquid by bubbling gases output by said hydropyrolysis through a recirculating liquid using a high boiling point portion of said substantially fully deoxygenated pyrolysis liquid. 
     
     
         11 . The process of  claim 1 , wherein output from said process consists essentially of liquid product and CO 2 . 
     
     
         12 . The process of  claim 8 , wherein said deoxygenation catalyst is granulated and sufficiently resistant to attrition such that it attrits said char, thereby enabling removal of said char from said fluidized bed reactor substantially only from above said fluidized bed. 
     
     
         13 . A process for producing liquid products from biomass comprising the steps of:
 introducing said biomass and reformed H 2  into a reactor vessel containing a deoxygenating catalyst and pyrolyzing said biomass, producing a pyrolysis process output comprising partially deoxygenated pyrolysis liquid, char, and a first portion of heat;   separating said char from said pyrolysis process output;   hydroconverting said partially deoxygenated pyrolysis liquid in the presence of a hydroconversion catalyst, producing substantially fully deoxygenated pyrolysis liquid, a gaseous mixture comprising CO and C 1 -C 5  light hydrocarbon gases and a second portion of heat; and   steam reforming a portion of said gaseous mixture, producing said reformed H 2 ; used in said reactor vessel,   
     
     
         14 . The process of  claim 13 , wherein in a range of about 40-60% of oxygen in said biomass is converted to H 2 O and about 40-60% of said oxygen is converted to CO and CO 2 . 
     
     
         15 . The process of  claim 13 , wherein said hydroconversion catalyst catalyzes both a water-gas-shift reaction and hydroconversion. 
     
     
         16 . The process of  claim 13 , wherein said hydropyrolyzing and said hydroconverting are carried out at substantially a same pressure. 
     
     
         17 . The process of  claim 16 , wherein said pressure is in a range of about 300 psig to about 800 psig. 
     
     
         18 . The process of  claim 13 , wherein said hydropyrolyzing is carried out at a hydropyrolysis temperature in a range of about 800° F. to about 950° F. and said hydroconverting is carried out at a hydroconversion temperature in a range of about 600° F. to about 800° F. 
     
     
         19 . The process of  claim 13 , wherein said substantially fully deoxygenated pyrolysis liquid is separated into diesel and gasoline fractions suitable for use as transportation fuel. 
     
     
         20 . The process of  claim 13 , wherein said reactor vessel is a fluidized bed reactor containing a fluidized bed. 
     
     
         21 . The process of  claim 13 , wherein output from said process consists essentially of liquid product and CO 2 .