A chemical method that could efficiently convert hemicellulose to furfural and simultaneously produce cellulose-enriched residue is encouraged as it remarkably promotes the economics of biorefinery process. However, few studies have focused on the co-production of furfural and cellulose-enriched residue.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) chose sugar cane bagasse (one of the commonly used biomass in furfural industry) as raw material for one-pot production of furfural and cellulose-enriched residue using AlCl3, FeCl3 and HCl as catalysts. They studied the degradation of sugar cane bagasse in a single aqueous system and in a 2-methyltetrahydrofuran (MTHF)/aqueous AlCl3 biphasic system. Their aim was to develop a process for the simultaneous production of furfural and easily hydrolyzable cellulose.
They found that conversion of bagasse in aqueous solution with FeCl3 and HCl benefited furfural 1 production from hemicellulose but degraded cellulose seriously. AlCl3 was more suitable to co-produce furfural and cellulosic residue from bagasse
Using AlCl3 replacing FeCl3 and HCl achieved lower furfural yield with less cellulose decomposition.Adding NaCl remarkably promoted furfural production in AlCl3-catalyzed system with less influence on the variation of residue composition. The introduction of MTHF increased furfural yield and reduced glucan content.
Under the best conditions (9 mL MTHF, 9 mL water, 0.1 M AlCl3, 150 oC, 45 min and 10 wt% NaCl), furfural yield of 58.6% was obtained while more than 90% of glucan was maintained in the residue.
After cycles, the organic phase was decanted and distilled to separate furfural and lignin and got purified MTHF. Lignin and furfural concentrations in the aqueous phase were low, they tended to solubilize in the organic phase. After many cycles, the aqueous phase could be purified by extraction with organic phase.