Reversion and dehydration reactions of glucose during the dilute sulfuric acid hydrolysis of cellulose
The inaccessibility of all glycosidic bonds necessitates industrial conversion schemes which employ a dilute acid catalyst at high temperatures. Process conditions also promote further reactions of glucose via the reversion and dehydration pathways. Quantitative determination of the yields of the major reversion and dehydration products is important for understanding and predicting the amounts of these materials expected under envisioned industrial operating conditions. Microcrystalline cellulose (Avicel) was hydrolyzed with sulfuric acid (0.0-1.25 wt.%), at high temperatures (160-250/sup 0/C), and at a 3:1 liquid-to-solid ratio. The hydrolysis was monitored by evaluating the amount of cellulose remaining and the yields of glucose, solid humin, levulinic acid, formic acid, hydroxymethylfurfural (HMF), and reversion products as a function of the aforementioned reaction conditions. Analysis of the reversion products required the development of a technique for the quantitation of trace carbohydrates in complex mixtures and led to the development of a reduction/permethylation gas chromatographic procedure. Cellulose hydrolysis followed pseudo-homogeneous first-order kinetics. Glucose yield was adequately described as consecutive first-order reactions. Anhydrosugars formed via reversion followed equilibrium reaction kinetics whereas the disaccharides did not. Total reversion product yields approached 10% at 250/sup 0/C. Quantitative determination of the major dehydration products provided important information concerning the destruction of glucose. HMF was produced in up to 12% yields based on the theoretical amount of glucose available, and furfural was detected in up to 5% yields. A carbon mass balance based on the determined product yields revealed that approximately 90% of all carbon was accounted for at maximum glucose yields.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 5380955
- Country of Publication:
- United States
- Language:
- English
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ACID HYDROLYSIS
ALDEHYDES
BY-PRODUCTS
CARBOHYDRATES
CELLULOSE
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHROMATOGRAPHY
DECOMPOSITION
DEHYDRATION
FURANS
FURFURAL
GAS CHROMATOGRAPHY
GLUCOSE
HETEROCYCLIC COMPOUNDS
HEXOSES
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROLYSIS
INORGANIC ACIDS
KINETICS
LYSIS
MASS BALANCE
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
POLYSACCHARIDES
REACTION KINETICS
SACCHARIDES
SEPARATION PROCESSES
SOLVOLYSIS
SULFURIC ACID
YIELDS