Torrefaction is an efficient thermochemical method to recover energy from lignocelluloses. In this work, bamboo was torrefied in diluted HCl solution (0-0.4 M) with microwave oven heating at 180 °C for 5-30 min. It was found that for bamboo torrefied in water, the yield of the torrefied bamboo decreased slightly from 96.15 to 85.53% and the hemicellulose content decreased from 30.45 to 25.00% with increased torrefaction severity from 3.3 to 3.6. Whereas for bamboo culm torrefaction in acid solutions, the yield of the solid fractions were below 51% and hemicelluloses were completely removed. Especially, the torrefaction with 0.2 M HCl solution for as short as 5 min resulted in the complete elimination of hemicelluloses, and the cellulose content decreased while the lignin content increased when further prolongation of the heating time to 30 min. This indicated that the acid solution played a role to intensify the decomposition of both hemicelluloses and cellulose. The carbon content of the bamboo was 48.82% and it increased slightly after torrefaction in water, but it raised largely up to 67.03% under torrefaction with 0.4 M HCl solution at 180 °C for 30 min. The HHV of the torrefied sample showed a higher value than that of the original sample and it increased after torrefaction at 0.2 M HCl for 30 min, which (24.86 MJ kg<sup>-1</sup>) was comparable with that of German Braunkohole lignite (25.10 MJ kg<sup>-1</sup> ). In addition, the structural modification of bamboo during the wet torrefaction was elucidated by XRD and NMR.

Microwave-assisted carbonization of bamboo by wet torrefaction in diluted acid

249th National Meeting (2015)

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