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Real time monitoring of slow pyrolysis of polyethylene terephthalate (PET) by different mass spectrometric techniques
Waste Management ( IF 8.1 ) Pub Date : 2020-03-30 , DOI: 10.1016/j.wasman.2020.03.028
Asma Dhahak , Christoph Grimmer , Anika Neumann , Christopher Rüger , Martin Sklorz , Thorsten Streibel , Ralf Zimmermann , Guillain Mauviel , Valérie Burkle-Vitzthum

In the context of waste upgrading of polyethylene terephthalate (PET) by pyrolysis, this study presents three on-line mass spectrometric techniques with soft ionization for monitoring the emitted decomposition products and their thermal dependent evolution profiles. Pyrolysis experiments were performed using a thermogravimetric analyzer (TGA) under nitrogen atmosphere with a heating rate of 5 °C/min from 30 °C to 600 °C. Single-photon ionization (SPI at 118 nm/10.5 eV) and resonance enhanced multiple photon ionization (REMPI at 266 nm) were used with time-of-flight mass spectrometry (TOF-MS) for evolved gas analysis (TGA-SPI/REMPI-TOFMS). Additionally, the chemical signature of the pyrolysis products was investigated by atmospheric pressure chemical ionization (APCI) ultra high resolution Fourier Transform ion cyclotron resonance mass spectrometry (FT-ICR MS) which enables assignment of molecular sum formulas (TGA-APCI FT-ICR MS). Despite the soft ionization by SPI, the fragmentation of some compounds with the loss of the [O-CH = CH2] fragment is observed. The major compounds were acetaldehyde (m/z 44), benzoic acid (m/z 122) and a fragment of m/z 149. Using REMPI, aromatic species were selectively detected. Several series of pyrolysis products were observed in different temperature intervals, showing the presence of polycyclic aromatic hydrocarbons (PAHs), especially at high temperatures. FT-ICR MS data showed, that the CHO4 class was the most abundant compound class with a relative abundance of 45.5%. The major compounds detected with this technique corresponded to m/z 193.0495 (C10H9O4+) and 149.0233 (C8H5O3+). Based on detailed chemical information, bulk reaction pathways are proposed, showing the formation of both cyclic monomer/dimer and linear structures.



中文翻译:

通过不同的质谱技术实时监测慢速热解聚对苯二甲酸乙二醇酯(PET)

在通过热解法对废聚对苯二甲酸乙二醇酯(PET)进行废物提质的背景下,本研究提出了三种具有软电离的在线质谱技术,用于监测排放的分解产物及其与热有关的演化曲线。使用热重分析仪(TGA)在氮气气氛下以30°C至600°C的加热速率为5°C / min进行热解实验。单光子电离(SPI在118 nm / 10.5 eV)和共振增强多光子电离(REMPI在266 nm)与飞行时间质谱(TOF-MS)一起用于析出气体分析(TGA-SPI / REMPI) -TOFMS)。另外,通过常压化学电离(APCI)超高分辨率傅里叶变换离子回旋共振质谱(FT-ICR MS)研究了热解产物的化学特征,该分析能够指定分子总和公式(TGA-APCI FT-ICR MS)。尽管通过SPI发生了软电离,但仍观察到某些化合物的碎片化,并丢失了[O-CH = CH2]碎片。主要化合物为乙醛(m / z 44),苯甲酸(m / z 122)和m / z 149片段。使用REMPI,可选择性检测芳香族物质。在不同的温度间隔内观察到几个系列的热解产物,表明存在多环芳烃(PAH),尤其是在高温下。FT-ICR MS数据显示,CHO 4类是最丰富的化合物类,相对丰度为45.5%。用该技术检测到的主要化合物对应于m / z 193.0495(C 10 H 9 O 4 +)和149.0233(C 8H 5 O 3 +)。根据详细的化学信息,提出了本体反应途径,表明了环状单体/二聚体和线性结构的形成。

更新日期:2020-03-31
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