CHANGES IN THE POLYSACCHARIDE COMPLEX OF LIGNOCELLULOSE AFTER CATALYTIC HYDROTHERMAL PRE-TREATMENT PROCESSING OF HEMP (CANNABIS SATIVA L.) SHIVES

摘要

Due to their high amount of pentosans, hemp (Cannabis sativa L.) shives are suitable for the productionrnof furfural - a platform chemical. However, after the catalytic hydrothermal pre-treatment process, 60-85 wt% ofrnlignocellulose (LC) is leftover, which also requires a rational utilization to realize the biorefinery concept. In thisrnstudy, the polysaccharide complex (cellulose and holocellulose) and its structural changes (α-, β-, γ-cellulose and thernaverage degree of polymerization) in the LC after obtaining furfural were investigated for the first time. The catalyticrnpre-treatment parameters were as follows: 140-180℃; Al2(SO_4)3 - 3, 5 and 7 wt%; 90 min. Autocatalysis was carriedrnout as a reference process. With an increase in the pre-treatment temperature, the degradation changes of cellulosernwere evidenced by the decreased amount of cellulose (from 41.7 to 20.5 wt%) and the average degree ofrnpolymerization (from 800 to 70). The decrease in the holocellulose content (from 71.9 to 29.1 wt%) and the absencernof γ-cellulose content (from 30.2 to 0.0 wt%) showed that hemicelluloses were removed from LC. The optimalrncatalytic hydrothermal pretreatment process parameters, when cellulose was slightly depolymerized to be morernaccessible for further processing, were a temperature of 160℃ and 5 wt% Al2(SO_4)3. During autohydrolysis in therntemperature range 140-180℃ the decrease in the average degree of polymerization was much more gradual than inrnthe case of catalytic pretreatment.