In wood hydrolysis, the hydrolytic degradation of cellulose is affected disadvantageously by the hydrolysis products of the hemicellulose that are formed simultaneously. In view of this point, a two-stage process, that the hemicellulose is hydrolyzed in the pretreatment step and then the cellulose is hydrolyzed, would be desirable.
The purpose of this research is to investigate the effect of reaction parameters on sugar yields and evaluate the kinetic parameters by using pine sawdust as raw material and sulfuric acid for catalyst.
It was found that the overall rate of the prehydrolysis depends upon acid concentration, non-hemicellulose concentration, temperature and the concentration of hemicellulose in the reaction mixture, and that of the main hydrolysis depends upon acid concentration, temperature, and the concentration of cellulose.
The reaction rate was found to be represented by :
Decomposition of hemicellulose to simple sugars in the prehydrolysis.
$r_H=2.275 × 10^{10}C_A^{1.011}C_N^{-0.856} exp (-20860/RT)C_H$
Decomposition of cellulose to glucose in the main hydrolysis.
$r_1=1.242 × 10^{19}C_A^{1.284} exp(-42570/RT)C_C$
Decomposition of glucose in the main hydrolysis.
$r_2=3.945 × 10^{14}C_A^{0.985} exp(-32880/RT)C_G$
According to the result of the scale-up and cost estimation for a plant capacity of 10 ton/day sawdust, total product cost is about 544,000 dollars. Annual total sugar production is 1146 tons and unit cost for sugar solution is 0.474 dollars/kg sugar.
