Optimization of reverse-flow, two-temperature, dilute-acid pretreatment to enhance biomass conversion to ethanol

Journal Article · Tue Dec 31 04:00:00 EST 1996 · Applied Biochemistry and Biotechnology

DOI:https://doi.org/10.1007/BF02941691· OSTI ID:598200

Torget, R; Hatzis, C; Hayward, T K ^[1]

---

1. National Renewable Energy Lab., Golden, CO (United States); and others

A reverse-flow, two-temperature dilute-acid prehydrolysis process of commercial yellow poplar sawdust using two percolation reactors was designed to simulate countercurrent flow of the biomass solids and prehydrolysis liquor, and to exploit the xylan biphasic kinetics. Lower temperatures (150-174{degrees}C) are initially applied to hydrolyze the easily hydrolyzable xylan, and higher temperatures (180-204{degrees}C) are applied to hydrolyze the remaining xylan. Two reactors were used to optimize each temperature range, using varying concentrations of sulfuric acid from 0.073-0.73 wt% and reaction times. Yields of soluble xylose, as high as 97% of theoretical, expressed as monomeric and oligomeric xylose, have been achieved with only 2.9% of the xylan being degraded to furfural, at concentrations of total potential sugar between 2.4 and 3.7 wt% before flashing. Depending on the combined severity of the acid concentration, residence time of the solids and liquor, and temperature of prehydrolysis, 81-100% of the hemicellulose, 3-32% of the glucans, and up to 46% of the Klason lignin could be solubilized. The lignocellulosic substrate produced from the pretreatment is readily converted to ethanol at a yield of approximately 91% of theoretical, with ethanol concentrations of up to 4.0 wt% in 55 h via a simultaneous saccharification and fermentation (SSF) process. In terms of xylose recovery and ethanol production level and rate, the present results are far superior to those previously reported using a single-temperature, dilute-acid pretreatment. 42 refs., 6 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 598200
• Report Number(s): CONF-950587--
• Journal Information: Applied Biochemistry and Biotechnology, Journal Name: Applied Biochemistry and Biotechnology Vol. 57-58; ISSN ABIBDL; ISSN 0273-2289
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOCONVERSION
BIOMASS
BUTYL ETHER
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CONCENTRATION RATIO
ENZYMATIC HYDROLYSIS
ETHANOL FUELS
FERMENTATION
FLASHING
FURFURAL
HEMICELLULOSE
LIGNIN
NATIONAL RENEWABLE ENERGY LABORATORY
OPTIMIZATION
PARTICLE SIZE
PRODUCTION
RENEWABLE ENERGY SOURCES
SACCHARIFICATION
SULFURIC ACID
TEMPERATURE RANGE
XYLANS
XYLOSE