Organic biomass paper pulping

Abstract

Fibrous organic biomass is converted into pulp in a flow-type process which uses pretreatment of the biomass, specific selection of acid and alkali agents and a low concentration of fiber to liquor.

1 . A method for pulping fibrous biomass comprising cellulose, hemicellulose and lignin components which comprises 
 a) decorticating, shredding or crushing said biomass;    b) concurrently with, or prior to step a), contacting said biomass with an aqueous solution of a nitrate ion source in the presence of an aluminum compound, to initiate nitration of said lignin component of said biomass;    c) soaking the resulting partially nitrated biomass in an aqueous solution of a nitrate ion source in the presence of an aluminum compound, wherein the wt:wt ratio of said solution to said biomass is at least about 15:1;    d) heating said solution of biomass to a temperature to complete desired nitration of said lignin component of said biomass;    e) draining said nitrated biomass;    f) contacting said nitrated biomass with an aqueous extraction solution of NH 4 OH, wherein the wt:wt ratio of aqueous solution:biomass is at least about 15:1;    g) heating said resultant solution to extract the hemicellulose and nitrated ligneous components of said biomass, thereby providing a partially defibered cellulosic material;    h) separating said partially defibered cellulosic structures from said extraction liquor containing said ligneous component; and    i) completely defibering said partially defibered cellulosic material.    
     
     
         2 . The method of  claim 1 , wherein said biomass comprises woody material, agricultural residue or grassy material.  
     
     
         3 . The method of  claim 2 , wherein said biomass comprises deciduous wood, grass, wheat straw, rice straw, barley straw, oat straw, corn stover, sugar cane, bagasse, kenaf or cotton stalks.  
     
     
         4 . The method of  claim 1 , wherein said nitrate ion source in steps b) and c) is HNO 3 .  
     
     
         5 . The method of  claim 4 , wherein said solution of HNO 3  in step b) comprises about 0.1% to about 3% HNO 3 .  
     
     
         6 . The method of  claim 5 , wherein said solution of HNO 3  in step b) comprises about 0.1% to about 1% HNO 3 .  
     
     
         7 . The method of  claim 4 , wherein said solution of HNO 3  in step c) comprises about 0.1% to about 3% HNO 3 .  
     
     
         8 . The method of  claim 7 , wherein said solution of HNO 3  in step c) comprises about 0.1% to about 1% HNO 3 .  
     
     
         9 . The method of  claim 1 , wherein the wt:wt ratio of aqueous solution of nitrate ion source: biomass in step c) is within the range of about 15:1 to about 25:1.  
     
     
         10 . The method of  claim 9 , wherein the wt:wt ratio is within the range of about 15:1 to about 20:1.  
     
     
         11 . The method of  claim 1 , wherein microwave energy is used to heat said solution of biomass of step d) and said solution of step g).  
     
     
         12 . The method of step  1 , wherein said biomass comprises wood flakes and said impregnation occurs within about 1 to about 3 hours.  
     
     
         13 . The method of  claim 1 , wherein said aluminum compound comprises Al 2 (SO 4 ) 3 —18H 2 O.  
     
     
         14 . The method of  claim 13 , wherein said aluminum compound is present at about 0.06 parts to about 0.11 parts per part (w:w) of HNO 3 .  
     
     
         15 . The method of step  1 , wherein said biomass comprises straw and said impregnation occurs within about 10 minutes to about 1 hour.  
     
     
         16 . The method of  claim 15 , wherein said microwave heating of step d) is carried out for a period of about 1 to about 5 minutes.  
     
     
         17 . The method of  claim 15 , wherein said microwave heating of step d) brings the temperature of said biomass to, and maintains said temperature at, about 100° C.  
     
     
         18 . The method of  claim 1 , wherein said drained biomass of step e) is washed with water at a temperature of about 90° to about 100° C. and drained again.  
     
     
         19 . The method of  claim 1 , wherein the wt:wt ratio of aqueous extraction solution:biomass in step f) is within the range of about 15:1 to about 25:1.  
     
     
         20 . The method of  claim 19 , wherein the wt:wt ratio is within the range of about 15:1 to about 20:1.  
     
     
         21 . The method of  claim 15 , wherein said microwave heating in step g) brings the temperature of said biomass to, and maintains it at, about 100° C.  
     
     
         22 . The method of  claim 1 , wherein said microwave heating in step g) is carried out for a period of from about 6 to about 11 minutes to about 30 minutes.  
     
     
         23 . The method of  claim 1 , which further comprises washing the completely defibered cellulosic material.  
     
     
         24 . The method of  claim 1 , which further comprises producing paper or board from said completely defibered cellulosic material.