Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
Phys Chem Chem Phys. 2011 Feb 14;13(6):2069-75. doi: 10.1039/c0cp00905a. Epub 2011 Jan 4.
Multiphase acid-catalyzed oxidation with hydrogen peroxide (H(2)O(2)) has been suggested recently to be a potential route to SOA formation from isoprene and its gas-phase oxidation products, the kinetics and chemical mechanism of this process have not been well-known yet. In this work, the uptake of 2-methyl-3-buten-2-ol (MBO), an important biogenic hydrocarbon and structurally similar to isoprene, into aqueous mixed solutions of H(2)O(2) and sulfuric acid (H(2)SO(4)) was performed using a rotated wetted-wall reactor coupled to a differentially pumped single-photon ionization time of flight mass spectrometer (RWW-SPI-TOFMS). The reactive uptake coefficients (γ) were acquired for the first time and the reaction pathways were deduced according to products information. The reactive uptake coefficients of MBO into H(2)SO(4)-H(2)O(2) mixed solutions are much greater than that into H(2)SO(4) solutions. Acetaldehyde, acetone and an on-line product, which transformed to isoprene readily in the duration of an off-line experiment, were suggested as products in this process. The further reactions of the carbonyl products can occur in acidic solution, which may play a role in SOA formation. Additionally, in real atmosphere the on-line product is apt to transform to isoprene, an acknowledged precursor of biogenic SOA. Thus, the multiphase acid-catalyzed oxidation of MBO with H(2)O(2) might be a potential contributor to SOA loading.
多相酸催化氧化与过氧化氢（H₂O₂）最近被认为是异戊二烯及其气相氧化产物形成 SOA 的潜在途径，但其动力学和化学机制尚未得到很好的了解。在这项工作中，使用旋转湿壁反应器与差分抽气单光子电离飞行时间质谱仪（RWW-SPI-TOFMS）相结合，将重要的生物碳氢化合物 2-甲基-3-丁烯-2-醇（MBO）吸入 H₂O₂和硫酸（H₂SO₄）的混合水溶液中。首次获得了反应性吸收系数（γ），并根据产物信息推断了反应途径。MBO 对 H₂SO₄-H₂O₂混合溶液的反应性吸收系数远大于对 H₂SO₄溶液的吸收系数。提出了乙醛、丙酮和一种在线产物作为该过程的产物，该产物在离线实验过程中很容易转化为异戊二烯。羰基产物的进一步反应可以在酸性溶液中发生，这可能在 SOA 形成中起作用。此外，在实际大气中，在线产物易于转化为异戊二烯，异戊二烯是生物 SOA 的公认前体。因此，MBO 与 H₂O₂的多相酸催化氧化可能是 SOA 负荷的一个潜在贡献者。
