Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO₂, CH₄, and O₂ depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N₂), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O₂ depletion.

中文翻译：

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储存经焙烧和蒸汽爆破的木材时挥发性有机化合物和永久性气体的离气

近年来，用于提升低价值原料以改善燃料特性的热处理已经引起了广泛的工业兴趣。从存储和运输的角度来看，由于活性生物质组分的降解，有害的废气排放有望减少。但是，热处理也会改变挥发性有机成分VOC的化学成分。当技术接近商业化时，产品的除气性能，特别是就VOC而言，仍是未知的。在本研究中，我们测量了密闭存储期间经过烘焙和蒸汽爆破的软木消耗的VOC以及CO，CO ₂，CH ₄和O _2的耗气量。储存温度，顶空气体（空气和N ₂），并且存储时间各不相同。使用新开发的协议监测挥发性有机化合物，该协议基于通过热解吸-GC / MS分析的Tenax TA吸收剂的主动采样。对于未经处理和经蒸汽爆炸的软木，发现VOC含量都很高，但其组成从原来占主导地位的萜烯转变为未经处理的木材样品的储气，到蒸汽爆炸的木材的顶部空间中存在大量的糠醛。烘焙过的材料排放的VOC含量低。通过多变量统计，结果表明，对于两种处理方法以及在所测试的范围内，VOC释放的气体首先受储存温度的影响，其次受到处理严重性的影响。蒸汽爆炸和烘焙过的生物量形成的CO含量均低于参考生物量，但蒸汽爆炸导致更严重的O ₂排放 消耗。