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Influence of step duration in fractionated Py-GC/MS of lignocellulosic biomass
Journal of Analytical and Applied Pyrolysis ( IF 6 ) Pub Date : 2019-01-01 , DOI: 10.1016/j.jaap.2018.11.026
M. González Martínez , T. Ohra-aho , D. da Silva Perez , T. Tamminen , C. Dupont

Abstract Fractionated pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC/MS) appears as an interesting analytical tool for elucidating lignocellulosic biomass structure, as it allows the progressive release of chemical fragments representative of biomass macromolecular composition. In this paper the effect of fractionated pyrolysis time (from 5 s to 300 s) on the degradation of lignin and carbohydrates from beech wood was studied at temperatures between 250 °C and 500 °C. Fractionated Py-GC/MS showed that the release temperature of the volatile degradation products varied between the volatile species detected. In addition, the step duration time changed the thermal degradation behavior of lignocellulosic components. Shortening the constant step duration time from 300 s to 5 s shifted the maximum weight loss to the higher temperatures. The result was opposite at long step duration times. Time optimization at each pyrolysis temperature (250 °C, 40 s; 300 °C, 30 s; 350 °C, 25 s; 370 °C, 20 s; 400 °C, 15 s; 450 °C, 10 s; 500 °C, 5 s) enhanced the yield of both lignin and carbohydrate volatile pyrolysis degradation products. In addition, two multiple temperature maxima were shown for some lignin and carbohydrate derivatives. This behavior may be due to the two different pathways of formation and macromolecular origins of compounds in beech wood. At optimized conditions lignin derivatives having a 3-carbon side chain substituent had a maximum at lower temperature than that of lignin derivatives with a 1-carbon side chain substituent. That phenomenon follows the order of primary and secondary pyrolysis reactions. Similar behaviors were observed among the degradation products of hemicelluloses and cellulose. Degradation products of hemicelluloses were mainly released at lower temperatures than those of cellulose derivatives, which illustrates the lower thermal stability of hemicelluloses compared to cellulose.

中文翻译:

步骤持续时间对木质纤维素生物质分馏 Py-GC/MS 的影响

摘要 分馏热解与气相色谱和质谱联用 (Py-GC/MS) 似乎是阐明木质纤维素生物质结构的一种有趣的分析工具,因为它允许逐渐释放代表生物质大分子组成的化学碎片。在本文中,研究了分馏热解时间(从 5 秒到 300 秒)在 250 °C 到 500 °C 之间的温度下对山毛榉木材中木质素和碳水化合物降解的影响。分馏 Py-GC/MS 表明挥发性降解产物的释放温度因检测到的挥发性物质而异。此外,步骤持续时间改变了木质纤维素组分的热降解行为。将恒定步骤持续时间从 300 秒缩短到 5 秒,将最大重量损失转移到更高的温度。结果与长步持续时间相反。每个热解温度下的时间优化(250 °C, 40 s; 300 °C, 30 s; 350 °C, 25 s; 370 °C, 20 s; 400 °C, 15 s; 450 °C, 10 s; 500 °C, 5 s) 提高了木质素和碳水化合物挥发性热解降解产物的产率。此外,对于一些木质素和碳水化合物衍生物,显示了两个多温度最大值。这种行为可能是由于山毛榉木材中化合物的两种不同的形成途径和大分子来源。在优化条件下,与具有 1 个碳侧链取代基的木质素衍生物相比,具有 3 个碳侧链取代基的木质素衍生物在较低温度下具有最大值。该现象遵循初级和次级热解反应的顺序。在半纤维素和纤维素的降解产物中观察到类似的行为。与纤维素衍生物相比,半纤维素的降解产物主要在较低的温度下释放,这说明半纤维素的热稳定性低于纤维素。
更新日期:2019-01-01
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