Bagasse fractionation for cellulosic ethanol and chemical production

摘要

A process is defined for the continuous steam pretreatment and fractionation of bagasse to produce a concentrated cellulose solid stream that is sensitive to enzymatic hydrolysis. Valuable chemicals are recovered by fractionating the liquid and vapor stream composed of hydrolysis and degradation products of the hemicellulose. Cellulosic derived glucose is produced for fermentation to biofuels. A hemicellulose concentrate is recovered that can be converted to value added products including ethanol.

主权项

1. A continuous process for fractionation of sugarcane bagasse biomass, consisting of the steps of:
a) subjecting the biomass to auto-hydrolysis treatment without the addition of acid or base to obtain a pre-hydrolyzed bagasse biomass by exposing the biomass to steam in a reaction vessel at a preselected temperature of between 170 and 220° C. and a preselected reaction pressure of between 100 and 322 psig, for a preselected exposure time of between 5 to 90 minutes, the process conditions being selected for the achievement of a severity index of 3.88 to 4.11, to remove a desired amount of a hemicellulose fraction from the bagasse biomass and to activate a cellulose fraction of the bagasse biomass and to obtain a pre-hydrolyzed bagasse biomass during the exposing step while continually purging liquid condensate and vapor formed during the exposure step to remove and collect a first liquid stream containing water soluble compounds and a first vapor stream containing volatile chemicals b) selectively extracting at the selected reaction pressure from the pre-hydrolysed bagasse biomass a second liquid stream containing hemicellulose hydrolysis and degradation components as a hemicellulose degradation stream; c) rapidly releasing the preselected reaction pressure after the extracting step for explosive decompression of the pre-hydrolyzed bagasse into pretreated fibrous solids, vapor and condensate; and d) collecting the vapor and condensate from the explosive decompression for separation and recovery of byproducts, e) optionally the bagasse biomass is adjusted to a moisture content of 50% to 70%, and is pre-heated to a temperature of about 100° C. for a minimum of about 10 minutes prior to pretreatment, f) optionally the pre-heated bagasse biomass is compressed prior to the exposure step to the selected pressure required for the exposure step for removing a third liquid stream containing extractives, g) optionally the first liquid stream from the pretreatment purge is blended with the second liquid stream extracted from the prehydrolysed bagasse biomass, h) optionally the bagasse biomass is washed and subsequently separated from dissolved hemicellulose and liqnin free xylo-oliqosaccharides and remaining inhibitory chemicals prior to the explosive decompression, i) optionally pretreated fibrous solids are washed with water, j) optionally wherein the washed fibrous solids are separated from the wash water by a separation process selected from the group consisting of compressing, filtering, centrifuging, and combinations thereof.