Effect of Particle Size on the Pretreatment of Okoumé Scrap: Formation of Degradation Products
摘要
The Okoumé wood (Aucoumea klaineana Pierre) was treated by steam explosion pretreatment. The effects of wood particle size on pretreatment efficiency and on the formation of degradation products were studied. A comparison of the sugar content of the treated biomass and the degradation chemistry related to particle size in Okoumé was carried out according to three particle size classes (2 mm, 1 mm and 0.16 mm) and at various degrees of severity after water impregnation. It has been observed that regardless of the particle size, a sharp decrease in xylose content is observed with the gradual increase in the severity of SE pretreatment. For example, for the 2 mm grain size class, there is a loss of xylose of 47.8% when the severity drops from 2.5 (170 °C, 2.5 min.) to 4.1 (210 °C, 7.5 min.). But a higher recovery of residual glucose and hydrolyzed xylose was obtained with the 2 mm particles at T = 210 °C and t = 7.5 min. However, under these conditions there is a higher production of degradation products: 4.1 (210 °C, 7.5 min, 2.64% formic acid for 0.16 mm) . The finer particle size range causes overcooking of the biomass and a strong degradation of the hydrolyzed sugars. Also, it was found that formic acid was the main degradation product regardless of the particle size and that its production was particularly high even for large particles, i.e. about 2% (20 g/kg) at T = 190 °C, t = 5 min. In all cases, the use of large particle sizes seems to be more beneficial for the biofuel recovery of the biomass studied because it saves grinding time and energy consumed. Also, the profitability of the biorefinery process in separate compounds associated with this particle size is higher.