Renewable Energy, Vol.168, 297-308, 2021
Selective production of furfural and phenols from rice husk: the influence of synergetic pretreatments with different order
The subject of this study was to upgrade the pyrolysis bio-oil by torrefaction combined with different order of acid washing. The pyrolysis behavior of biochar obtained from different pretreatments were investigated by a thermogravimetric analyzer (TGA) and fixed furnace. Moreover, the composition of biooil was systematically analyzed by GC-MS. The results showed that torrefaction promoted the aggregation of phenols in bio-oil through removing the hemicellulose and part of cellulose. In addition, aldehydes had increased significantly after acid washing. The acid washing combined with torrefaction could reduce the formation of acids, alcohols and other organic substances except for phenols, aldehydes and ketones. Compared with the pyrolysis bio-oil obtained by directly torrefaction pretreatment, the absolute content of phenols in the pyrolysis bio-oil was slightly reduced from 74 mg/gRH to 63 mg/gRH after first inorganic acid washing and then torrefaction, while the absolute content of furfural increased from 2.8 mg/gRH to 16 mg/gRH. The mechanism showed that the furfural was selected by the catalysis of acid and the torrefaction promoted the cellulose to convert to 1-hydroxy-2-propanone by cracking reaction. This study provided a simple and practical method for the selective production of furfural and phenol from rice husk. (c) 2020 Elsevier Ltd. All rights reserved.