Ethanol from lignocellulose; An overview
Ethanol, a liquid fuel compatible with today's transportation system, can be produced by biological processes from lignocellulosic feedstocks. Biomass in an attractive feedstock for ethanol production because it is available in large quantities at low cost. Biological processes are very efficient, but each fraction of the lignocellulosic feedstock must be processed separately. Cellulose (a crystalline polymer of glucose), the structural core, comprises 40% of the feedstock. It is difficult to hydrolyze (break down) into glucose, but once formed, the glucose is readily fermented to ethanol. Cellulose can be hydrolyzed with either acid or enzymatic catalysts. Using acids, the chief problem is that conditions severe enough to promote hydrolysis also degrade the glucose, resulting in low (55%-80%) yields. Enzymatic processes are potentially much more efficient because enzymes catalyze only the hydrolysis reaction. However, these processes are much newer and less developed. Research is required to develop methods to make lignocellulose more digestible, to produce more active enzymes at lower cost, and to develop methods of hydrolysis where enzyme action is not inhibited by reaction end products. Approximately 30% of the feedstock is hemicellulose, which is largely made of xylan (a polymer of xylose). Xylan is easily hydrolyzed, but it is difficult to ferment to ethanol. Several potential methods of fermentation have been identified, but it is not yet clear which is the most promising. Lignin, the final major component, is a phenolic polymer that cannot be fermented to ethanol. However, it can be broken down to phenolic monomers, hydrotreated, and reacted with methanol to produce methyl aryl ethers, a high-octane gasoline additive. 21 refs., 11 figs., 1 tab.
- Research Organization:
- Solar Energy Research Inst., Golden, CO (USA)
- DOE Contract Number:
- AC02-83CH10093
- OSTI ID:
- 6437148
- Report Number(s):
- SERI/TP-231-3194; CONF-870822-3; ON: DE87001199
- Resource Relation:
- Conference: American Institute of Chemical Engineers summer national meeting, Minneapolis, MN, USA, 16 Aug 1987; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Ethanol from lignocellulosic biomass
Related Subjects
CELLULOSE
ACID HYDROLYSIS
ENZYMATIC HYDROLYSIS
ETHANOL
PRODUCTION
LIGNIN
ECONOMIC ANALYSIS
ALCOHOLS
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
ECONOMICS
HYDROLYSIS
HYDROXY COMPOUNDS
LYSIS
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SOLVOLYSIS
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