Corncob lignocellulose for the production of furfural by hydrothermal pretreatment and heterogeneous catalytic process
Corncob with a high content of pentose-rich hemicelluloses shows great potential for furfural production. In this paper, an environmentally-friendly two-step process for furfural production was developed by the hydrothermal pretreatment of corncob and the heterogeneous catalysis of the hydrolysate using a solid acid catalyst. The hydrothermal pretreatment was applied to release hemicelluloses from the cell wall of the corncob, which were hydrolyzed into monosaccharide and oligosaccharide under the investigated conditions (160–190 °C, 0–60 min). Subsequently, heterogeneous catalysis of the hydrolysate obtained from the hydrothermal pretreatment was performed using SO42−/SiO2–Al2O3/La3+ as a solid acid catalyst at 150 °C for 2.5 h. The maximum yield of furfural achieved was up to 21% under the investigated experimental conditions from the catalysis of hydrolysates obtained at 190 °C for 60 min in the hydrothermal process. Moreover, there was no obvious change in the catalytic activity of SO42−/SiO2–Al2O3/La3+ after four runs, and only a decline of 5.28% yield of furfural was observed. This two-step process is an environmentally-friendly process for furfural production from pentose-rich biomass and serves as an effective approach for recovering the solid catalyst from the reaction medium.