State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
Environ Sci Technol. 2010 Mar 15;44(6):2035-41. doi: 10.1021/es9037275.
The heterogeneous reactions of methacrolein (MAC) and methyl vinyl ketone (MVK) on α-Al(2)O(3) surfaces have been studied in a flow reactor using transmission-Fourier Transform Infrared (T-FTIR) spectroscopy to monitor the reaction progress. Unlike SiO(2) particles where MAC and MVK are weakly physisorbed, the results in this work demonstrate that on c-AlO3 particles MAC and MVK are irreversibly adsorbed and can rapidly react on the surface to form various products such as aldehydes, organic acids, hydrogen peroxide, and even higher molecular weight compounds. The initial uptake rates and initial uptake coefficients for MAC and MVK on α-Al(2)O(3) under dry conditions were determined to explore the reactivity of the particles. Furthermore, the effect of water vapor on the heterogeneous reactions was also investigated as a function of relative humidity. Both the heterogeneous uptake and transformation of MAC and MVK on α-Al(2)O(3) were largely suppressed under humid conditions due to the depletion of surface active sites by water molecules. On the basis of experimental results, atmospheric implications of heterogeneous reactions of MAC and MVK were discussed. Our work suggests that heterogeneous reactions on α-Al(2)O(3) can be important sinks for MAC and MVK as well as possible contributors to atmospheric organic aerosol.
在流动反应器中，使用传输傅里叶变换红外（T-FTIR）光谱法研究了异质反应甲丙烯醛（MAC）和甲基乙烯基酮（MVK）在α-Al（2）O（3）表面上的反应，以监测反应进程。与在 SiO（2）颗粒上 MAC 和 MVK 被弱物理吸附的情况不同，这项工作的结果表明，在 c-AlO3 颗粒上，MAC 和 MVK 被不可逆地吸附，并且可以在表面上迅速反应，形成各种产物，如醛、有机酸、过氧化氢，甚至更高分子量的化合物。在干燥条件下，确定了α-Al（2）O（3）上 MAC 和 MVK 的初始吸收速率和初始吸收系数，以探索颗粒的反应性。此外，还研究了水蒸气对异质反应的影响，作为相对湿度的函数。由于水分子耗尽了表面活性位，因此在潮湿条件下，MAC 和 MVK 的异质吸收和转化都受到了很大的抑制。基于实验结果，讨论了 MAC 和 MVK 的异质反应对大气的影响。我们的工作表明，α-Al（2）O（3）上的异质反应可以是 MAC 和 MVK 的重要汇，也是大气有机气溶胶的可能贡献者。
