利用傅里叶变换红外光谱测量甲苯光氧化产物

Measurement of Photooxidation Products of Toluene by Fourier Transform Infrared Spectroscopy

甲苯是大气中主要的挥发性有机污染物和二次有机气溶胶的前体物。采用自制的烟雾腔模拟装置研究了无氨和有氨时由羟基启动的甲苯光氧化过程,利用傅里叶变换衰减全反射红外光谱测量了甲苯光氧化产物的分子官能团,并对其化学组分进行了定性分析。实验结果表明,两种情况下的甲苯光氧化产物中都含有苯环、O-H、C=O和C-O等官能团,并含有较高浓度的甲基酚、醛、酮和羧酸等有机物。而有氨时的甲苯光氧化产物中还含有C=N、C-N和N-H等官能团,它们对应于咪唑类含氮有机物的化学键特性。该结果为研究甲苯光氧化反应机理提供了新的实验依据。

Toluene is the major volatile contaminant and secondary organic aerosol precursor in at mosphere. A home-made smog chamber is used to study the OH-initiated photooxidation process of toluene in the absence and presence of ammonia. The molecular functional groups of the photooxidation products of toluene are measured by a Fourier transform attenuated total reflection infrared spectrometer. The chemical components of the products are analyzed qualitatively. The experimental results show that there are functional groups such as benzene ring, O-H, C=O and C-O in the photooxidation products of toluene both with and without ammonia and high concentration organic compounds such as cresol, aldehydes and carboxylic acids are contained in the groups. However, in the presence of ammonia, C=N, C-N,N-H and other functional groups corresponding to the imidazole nitrogen-contained organic compounds are also contained in the photooxidation products of toluene. These results provide new experimental basis for the study of the photooxidation mechanism of toluene.