To 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.

中文翻译：

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焙烧过程中竹废料的化学和结构转变

为了研究竹子在焙干过程中的化学和结构转变，在200、250和300°C的温度下焙烧了竹屑，停留时间为1.0、1.5和2.0 hr，通过热重分析和质谱法确定了其性质。 （PY-MS），傅立叶变换红外光谱仪（FTIR），X射线衍射（XRD）和固态核磁共振谱（NMR）。结果表明，焙烧提高了竹废料的能量密度和热值，减少了其挥发性物质和污染物的排放。竹废料的化学和结构转变是由于某些化学基团的热解所致。焙烧温度比停留时间具有更显着的影响。能量富集系数（EEF），发热量提高（CVI），随着焙烧温度和停留时间的增加，焙烧竹废料的燃料比（FR）增加。当焙干温度升至300℃时，纤维素的结晶区被破坏。热解产物有10多个族，包括醇，酸，醛，烷烃，酯，醚，呋喃，酮，苯酚等。焙烧作用改变了愈创木酚单元，β-O-4的芳族化合物中H原子的化学环境。结构，β-β结构为木聚糖。β-O-4键在愈创木单元中断裂，形成芳构化和烷基侧链。研究结果将有助于揭示竹废料的烘烤机理，并进一步发展其作为能源产品的增值利用。当焙干温度升至300℃时，纤维素的结晶区被破坏。热解产物有10多个族，包括醇，酸，醛，烷烃，酯，醚，呋喃，酮，苯酚等。焙烧作用改变了愈创木酚单元，β-O-4的芳族化合物中H原子的化学环境。结构，β-β结构为木聚糖。β-O-4键在愈创木单元中断裂，形成芳构化和烷基侧链。研究结果将有助于揭示竹废料的烘烤机理，并进一步发展其作为能源产品的增值利用。当焙干温度升至300℃时，纤维素的结晶区被破坏。热解产物有10多个族，包括醇，酸，醛，烷烃，酯，醚，呋喃，酮，苯酚等。焙烧作用改变了愈创木酚单元，β-O-4的芳族化合物中H原子的化学环境。结构，β-β结构为木聚糖。β-O-4键在愈创木单元中断裂，形成芳构化和烷基侧链。研究结果将有助于揭示竹废料的烘烤机理，并进一步发展其作为能源产品的增值利用。焙烧将H原子的化学环境从愈创木单元，β-O-4结构，β-β结构的芳族化合物转变为木聚糖。β-O-4键在愈创木单元中断裂，形成芳构化和烷基侧链。研究结果将有助于揭示竹废料的烘烤机理，并进一步发展其作为能源产品的增值利用。焙烧将H原子的化学环境从愈创木单元，β-O-4结构，β-β结构的芳族化合物转变为木聚糖。β-O-4键在愈创木单元中断裂，形成芳构化和烷基侧链。研究结果将有助于揭示竹废料的烘烤机理，并进一步发展其作为能源产品的增值利用。