The chemical and structural transformation of bamboo wastes during torrefaction process

Abstract

AbstractTo investigate the chemical and structural transformation of bamboo during torrefaction process, bamboo wastes were torrefied at temperatures of 200, 250, and 300°C and residence times of 1.0, 1.5, and 2.0 hr, whose properties were determined by thermogravimetry coupled with mass spectrometry (PY‐MS), Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), and solid‐state nuclear magnetic resonance spectroscopy (NMR). The results showed that torrefaction improved the energy density and calorific value, reduced the volatile matters, and pollutant emission of bamboo wastes. The chemical and structural transformation of bamboo wastes was due to pyrolysis of some chemical groups. Torrefaction temperatures had the more significant effect than residence times. The energy enrichment factor (EEF), the calorific value improvement (CVI), and fuel ratio (FR) of torrefied bamboo wastes increased with the increase of torrefaction temperatures and residence times. When torrefaction temperatures increased to 300°C, crystalline region of cellulose was destroyed. There were more than 10 families of pyrolysis products, including alcohol, acid, aldehyde, alkane, ester, ether, furan, ketone, phenol, etc. Torrefaction changed the chemical environment of H atoms from aromatics of guaiacs unit, β‐O‐4 structure, β‐β structure to xylan. The β‐O‐4 bond was broken in guaiacle unit and formed aromatization and alkyl side chains. The results will be helpful to reveal torrefaction mechanism of bamboo wastes and further develop their add‐valued utilization as energy products.