Conversion of waste cellulose to ethanol. Phase II. Reaction kinetics with phosphoric acid
Waste cellulosic material can be hydrolyzed in dilute acid solution to produce fermentable sugars which can then be converted into ethanol. A laboratory investigation was made of the feasibility of using phosphoric acid as the hydrolysis catalyst. The hydrolysis reaction with phosphoric acid solutions was compared with the reaction employing the more conventional dilute sulfuric acid catalyst. The purpose of this research was to examine the hydrolysis step in a proposed process for the conversion of cellulose (from wood, newspapers, municipal solid waste, or other sources) into ethanol - by which a potentially valuable co-product, DICAL (dicalcium phosphate), might be made and sold with or without the lignin content as a fertilizer. The pertinent reaction kinetics for the acid catalyzed production of glucose from cellulose consists of consecutive, pseudo-first order reactions. The first reaction forms glucose by hydrolyzing the cellulose polymer and a subsequent reaction decomposes the glucose. The maximum theoretical yield depends on the ratio of the rate constants for these two reactions. The rate constants of both reactions were measured in a series of experiments studying temperature and concentration effects. The results suggest that the glucose decomposition reaction is similar with the two acids but that the cellulose hydrolysis reaction mechanism with phosphoric acid may be different than with sulfuric acid. The studies show phosphoric acid is unpromising and much inferior to sulfuric acid as the catalytic agent. Under the conditions studied, 0.8 wt % sulfuric acid gives a greater yield of glucose than 8.0 wt % phosphoric acid.
- Research Organization:
- University of North Alabama, Florence (USA). Dept. of Chemistry
- OSTI ID:
- 5354736
- Report Number(s):
- TVA/OP/EDT-82/42; ON: DE82906111
- Country of Publication:
- United States
- Language:
- English
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CARBOHYDRATES
CATALYSIS
CELLULOSE
CHEMICAL REACTIONS
DECOMPOSITION
DIAGRAMS
FLOWSHEETS
HYDROGEN COMPOUNDS
HYDROLYSIS
INORGANIC ACIDS
KINETICS
LIGNIN
LYSIS
ORGANIC COMPOUNDS
PHOSPHORIC ACID
POLYSACCHARIDES
REACTION KINETICS
SACCHARIDES
SOLVOLYSIS
SULFURIC ACID
YIELDS