Catalytic fast pyrolysis process

Abstract

The present invention provides an improved catalytic fast pyrolysis process for increased yield of useful and desirable products. The process comprises the steps of: a) feeding biomass, a specific catalyst composition and transport fluid to a catalytic fast pyrolysis process fluidized bed reactor maintained at reaction conditions to manufacture a raw fluid product stream, b) feeding the raw fluid product stream of step a) to a catalyst separation and stripping system to produce separated catalyst and a fluid product stream, c) feeding the fluid product stream of step b) to a vapor/liquid separation system to produce a liquid phase stream and a vapor phase stream comprising benzene, toluene and xylenes, d) feeding the vapor phase stream of step c) to a product recovery system to recover benzene, toluene and xylenes, and e) recycling at least a portion of the recovered toluene of step d) to the fluidized bed reactor of step a).

What is claimed is: 
     
         1 . An improved catalytic fast pyrolysis process comprising steps of:
 a) feeding biomass, catalyst composition, and transport fluid to a catalytic fast pyrolysis process fluidized bed reactor maintained at reaction conditions to manufacture a raw fluid product stream,   b) feeding the raw fluid product stream of step a) to a solids separation and stripping system to produce separated solids and a fluid product stream,   c) feeding the fluid product stream of step b) to a vapor/liquid separation system to produce a liquid phase stream comprising components selected from the group consisting of water, char, coke, ash, catalyst fines and combinations thereof, and a vapor phase stream comprising benzene, toluene and xylenes,   d) feeding the vapor phase stream of step c) to a product recovery system to recover benzene, toluene and xylenes, and   e) recycling at least a portion of the recovered toluene of step d) to the fluidized bed reactor of step a).   
     
     
         2 . The process of  claim 1  wherein the crystalline molecular sieve of the catalyst composition of step a) is characterized by a silica/alumina mole ratio greater than 12 and a Constraint Index from 1 to 12. 
     
     
         3 . The process of  claim 1  wherein the fluidized bed reaction conditions include a temperature of from 300 to 1000° C. and pressure from 100 to 1500 kPa. 
     
     
         4 . The process of  claim 2  wherein the crystalline molecular sieve of the catalyst composition of step a) is characterized by a silica/alumina mole ratio from greater than 12 to 240 and a Constraint Index from 5 to 10. 
     
     
         5 . The process of  claim 2  wherein the catalyst composition of step a) comprises a crystalline molecular sieve having the structure of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-50 or combinations thereof. 
     
     
         6 . The process of  claim 4  wherein the catalyst composition of step a) comprises a crystalline molecular sieve having the structure of ZSM-5, ZSM-11, ZSM-22, ZSM-23 or combinations thereof. 
     
     
         7 . The process of  claim 5  wherein the catalyst composition of step a) comprises a crystalline molecular sieve having the structure of ZSM-5. 
     
     
         8 . The process of  claim 1  wherein from 5 to 99% of the recovered toluene of step d) is recycled to the fluidized bed reactor of step a). 
     
     
         9 . The process of  claim 8  wherein from 30 to 50% of the recovered toluene of step d) is recycled to the fluidized bed reactor of step a). 
     
     
         10 . The process of  claim 1  wherein the solids separation and stripping system of step b) comprises a cyclone or series of cyclones. 
     
     
         11 . The process of  claim 1  wherein the vapor/liquid separation system of step c) comprises venturi systems, quench systems, condensers, chillers, absorption systems, scrubbers, demisters, or combinations thereof. 
     
     
         12 . The process of  claim 1  wherein the product recovery system of step d) comprises condensers, chillers, absorption systems, demisters, or combinations thereof. 
     
     
         13 . An improved catalytic fast pyrolysis process comprising steps of:
 a) feeding biomass, catalyst composition comprising a crystalline molecular sieve having the structure of ZSM-5, and transport fluid to a catalytic fast pyrolysis process fluidized bed reactor maintained at reaction conditions including a temperature from 300 to 1000° C., pressure from 100 to 1500 kPa and catalyst-to-biomass mass ratio of from 0.1 to 40 to manufacture a raw fluid product stream,   b) feeding the raw fluid product stream of step a) to a solids separation and stripping system to produce separated solids and a fluid product stream,   c) feeding the fluid product stream of step b) to a vapor/liquid separation system to produce a liquid phase stream comprising components selected from the group consisting of water, char, coke, ash, catalyst fines and combinations thereof, and a vapor phase stream comprising benzene, toluene and xylenes,   d) feeding the vapor phase stream of step c) to a product recovery system to recover benzene, toluene and xylenes, and   e) recycling from 5 to 99% of the recovered toluene of step d) to the fluidized bed reactor of step a).   
     
     
         14 . The process of  claim 13  wherein the catalyst composition comprises binder material selected from the group consisting of porous inorganic oxide, clay or combinations thereof. 
     
     
         15 . The process of  claim 14  wherein the inorganic oxide comprises alumina, zirconia, silica, magnesia, thoria, titania, boria or combinations thereof. 
     
     
         16 . The process of  claim 14  wherein the clay comprises bentonite, kieselguhr or combinations thereof. 
     
     
         17 . The process of  claim 13  wherein from 30 to 50% of the recovered toluene of step d) is recycled to the fluidized bed reactor of step a).