Controlled ph biomass treatment

Abstract

A method for treating biomass including lignocellulosic polymers. The biomass is treated in a mixture of water with at least one oxidizing agent and steam at a temperature in a range of from about 130° C. to about 220° C. for a period from about 5 seconds to about 10 hours. The pH of the mixture is periodically measured for substantially an entire duration of the treating step. As necessary, based on the measured pH of the mixture, adjusting the pH of the mixture into a range of from about pH 4.5 to about pH 7.5 by adding a base to the mixture.

1 . A method for treating biomass comprising lignocellulosic polymers, said method comprising steps of:
 (a) treating a mixture of the biomass and water with at least one oxidizing agent and steam at a temperature in a range of from about 130° C. to about 220° C. for a period from about 5 seconds to about 10 hours;   (b) periodically measuring a pH of the mixture for substantially an entire duration of step (a); and   (c) as necessary, based on the pH of the mixture measured in step (b), adjusting the pH of the mixture into a range of from about pH 4.5 to about pH 7.5 by adding a base to the mixture.   
     
     
         2 . The method of  claim 1 , wherein the biomass is selected from agricultural wastes, wood wastes and gardening wastes. 
     
     
         3 . The method of  claim 1 , wherein the biomass is selected from corn stover, corn cobs, palm tree empty fruit bunches, sugar cane bagasse, straw from grain crops, hay, wood waste from thinnings of deciduous and conifer forestry, sawdust from lumbering and furniture making, guayule residuals after natural rubber extraction, waste paper and cardboard. 
     
     
         4 . The method of  claim 1 , wherein the at least one oxidizing agent is selected from air, oxygen enriched air, oxygen, ozone, perchlorates, carbon dioxide, nitrous oxide, oxides, superoxides, permanganates, chlorates, peroxides, hypochlorites, or nitrates. 
     
     
         5 . The method of  claim 4 , wherein the at least one oxidizing agent is selected from air, oxygen and oxygen enriched air. 
     
     
         6 . The method of  claim 5 , wherein a weight ratio of oxygen in introduced by the at least one oxidizing agent during the treatment process to carbon in the biomass is in a range of from about 0.2 to about 1.0. 
     
     
         7 . The method of  claim 1 , wherein the pH of the mixture is from pH about 4.5 to about 7.0. 
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 1 , wherein the pH is measured about once every second, to once every hour and the pH is measured at least 2 times during the treatment step. 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein the base is selected from oxides, hydroxides, carbonates, borates, and halogenates of Group I and Group II elements. 
     
     
         12 . The method of  claim 1 , wherein the base is selected from ammonia, ammonium hydroxide, urea and combinations thereof. 
     
     
         13 . The method of  claim 1 , wherein an amount of the base added to the mixture is in the range of from about 1 to about 10 wt. %, based on the dry range of the biomass. 
     
     
         14 . The method of  claim 1 , wherein an amount of the steam used in the treatment step is from about 0.1 to about 0.5 wt. %, based on a dry weight of the biomass. 
     
     
         15 . The method of  claim 1 , wherein the temperature is in a range of from about 130° C. to about 210° C. 
     
     
         16 . The method of  claim 1 , wherein the oxidizing step is performed under a pressure in a range of from about 201.3 KPa to about 2068 KPa. 
     
     
         17 . The method of  claim 1 , wherein the period of the treating step is from about 10 seconds to about 9 hours and the treating step has a severity factor in a range of from about 2.5 to about 4.5. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 1 , wherein the mixture further comprises an oxidation catalyst selected from water insoluble metals, transition metals, precious metals, their salts or oxides, and combinations thereof and the oxidation catalyst comprises a metal selected from nickel, cobalt, platinum, palladium, rhenium, iron, copper, vanadium, zirconium and ruthenium. 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 1 , further comprising a step of preprocessing the biomass selected from grinding, milling and crushing the biomass to reduce an average particle size of the biomass to from 0.2 mm to 12 cm. 
     
     
         22 . The method of  claim 1 , further comprising a step d) selected from enzymatic treatment using at least one enzyme selected from xylanases, cellulases, hemicellulases, xylosidase, esterase, arabinofuranosidase, galactanase, oxidases, peroxidases, mannases, laccases, oxidoreductases, pectinases and lipases; and fermentation. 
     
     
         23 . (canceled) 
     
     
         24 . The method of  claim 22 , wherein the at least one enzyme comprises at least one cellulase and at least one hemicellulose. 
     
     
         25 . (canceled) 
     
     
         26 . The method of  claim 22 , wherein step d) comprises fermentation in a microbial digester using at least one microorganism selected from bacteria, and fungi and the at least one enzyme is produced by a bacteria or fungus used for the fermentation.