LP-FTIR研究CH_3C(O)CH═CH_2与O_3大气反应生成过氧化物的产率

Study on the Yield of Peroxides from Atmospheric Reaction of CH_3C(O)CH═CH_2 with O_3 by Long Path FTIR

在 (2 98± 2 )K温度和 1 0× 10 5Pa (2 0 %O2 +80 %N2 )压力条件下 ,采用长光路傅里叶变换红外光谱(LP FTIR)技术 ,实验室模拟研究甲基乙烯基酮 (CH3 C (O)CHCH2 )与O3 大气化学反应。从FTIR光谱中可以看出 ,产物中包括HCHO ,HC (O)OH ,CH3 CHO和CH3 C (O)CHO等羰基化合物 ,还有CO ,CO2 等。FTIR结合双通道过氧化物分析仪 ,测定了过氧化物的产率。其中 ,有机氢过氧化物 (ROOH )为(10 7± 0 4 ) % ,过氧化氢 (H2 O2 )为 (1 8± 0 3) %。HPLC分析表明 ,ROOH主要为甲基过氧化氢 (CH3 OOH)。可以认为 ,作为异戊二烯主要中间产物之一的甲基乙烯基酮与O3 的反应是大气有机过氧化物的一个重要来源。至于反应过程中有机过氧化物的生成浓度呈现双峰的特征 ,其机制需作进一步的研究。

At the temperature of (298 +/- 2) K and pressure of 1.0 x 10(5) Pa(20% O-2+ 80% N-2), the experimental simulation was employed to study the atmospheric chemical reaction of methyl vinyl ketone (MVK, CH3C(O)CH=CH2) with O-3 in the dry air, using long path Fourier transform infrared(LP-FTIR) spectrometry. From FTIR spectra, in addition to CO and CO2 some carbonyl compounds were found including HCHO, HC(O)OH, CH3CHO and CH3C(O)CHO. By combination of FTIR and the dual channel peroxide analytical instrument, peroxide yields were determined with the results of (10.7 +/- 0.4) % for organic hydroperoxide (ROOH) and (1.8 +/- 0.3) % for hydrogen peroxide (H2O2), respectively. The plot of organic hydroperoxide concentration vs. reaction time showed a double-peak curve; however, its formation cause is unclear, necessary to be further studied. High performance liquid chromatography (HPLC) analysis showed that CH3OOH was the major organic peroxide under our reaction conditions. The result implies that as one of the main intermediate products of isoprene atmospheric reaction, MVK reaction with O-3 is an important source of organic peroxides in the atmosphere.