Kumagai Shogo, Takahashi Yusuke, Kameda Tomohito, Saito Yuko, Yoshioka Toshiaki
Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
ACS Omega. 2021 Apr 26;6(18):12022-12026. doi: 10.1021/acsomega.1c00622. eCollection 2021 May 11.
Pyrolysis of cellulose primarily produces 1,6-anhydro-β-d-glucopyranose (levoglucosan), which easily repolymerizes to form coke precursors in the heating zone of a pyrolysis reactor. This hinders the investigation of primary pyrolysis products as well as the elucidation of cellulose pyrolysis mechanisms, particularly because of the significant buildup of coke during slow pyrolysis. The present study discusses the applicability of a pyrolysis-gas chromatography/flame ionization detection (Py-GC/FID) system using naphthalene as the internal standard, with the aim of substantially improving the quantification of pyrolyzates during the slow pyrolysis of cellulose. This method achieved quantification of levoglucosan with a yield that was 14 times higher than that obtained from offline pyrolysis in a simple tube reactor. The high yield recovery of levoglucosan was attributed to the suppression of levoglucosan repolymerization in the Py-GC/FID system, owing to the rapid escape of levoglucosan from the heating zone, low concentration of levoglucosan in the gas phase, and rapid quenching of levoglucosan. Therefore, this method facilitated the improved quantification of primary pyrolysis products during the slow pyrolysis of cellulose, which can be beneficial for understanding the primary pyrolysis reaction mechanisms. This method can potentially be applied to other polymeric materials that produce reactive pyrolyzates.
纤维素的热解主要产生1,6-脱水-β-D-吡喃葡萄糖（左旋葡聚糖），其在热解反应器的加热区容易再聚合形成焦炭前驱体。这阻碍了对初级热解产物的研究以及纤维素热解机理的阐明，特别是因为在慢速热解过程中焦炭大量堆积。本研究讨论了以萘为内标的热解-气相色谱/火焰离子化检测（Py-GC/FID）系统的适用性，目的是大幅提高纤维素慢速热解过程中热解产物的定量分析。该方法实现了左旋葡聚糖的定量分析，其产率比在简单管式反应器中离线热解获得的产率高14倍。左旋葡聚糖的高产率回收归因于在Py-GC/FID系统中左旋葡聚糖再聚合受到抑制，这是由于左旋葡聚糖从加热区快速逸出、气相中左旋葡聚糖浓度低以及左旋葡聚糖快速淬灭。因此，该方法有助于改进纤维素慢速热解过程中初级热解产物的定量分析，这对于理解初级热解反应机理可能是有益的。该方法有可能应用于其他产生反应性热解产物的聚合物材料。
