Trubitsyn Dmitry A, Vorontsov Alexander V
Boreskov Institute of Catalysis, pr. Ak. Lavrentieva 5, Novosibirsk 630090, Russia.
J Phys Chem B. 2005 Nov 24;109(46):21884-92. doi: 10.1021/jp053793q.
Removal from air and decomposition of dimethyl methylphosphonate (DMMP) over high surface area anatase TiO(2) at ambient temperature have been quantitatively studied by employing Fourier transform infrared (FTIR) technique under static conditions. In the first scenario of air purification, DMMP underwent reactive adsorption that upon completion was followed by photocatalytic oxidation. DMMP was captured over the TiO(2) surface at the speed of external diffusion. Hydrolysis of adsorbed DMMP led to methanol and methyl methylphosphonate (MMP). At low DMMP coverage quantity, it hydrolyzed completely with the formation of completely surface-bound methanol at 1% relative humidity (RH) and mostly gaseous methanol at 50% RH. Photocatalytic oxidation generated CO(2) as the only carbonaceous gaseous product and bidentate formates as the intermediate surface product. At high DMMP coverage quantity, it was captured incompletely and hydrolyzed partially with CH(3)OH in the gas phase only, 50% RH enhancing both processes. Photocatalytic oxidation generated gaseous HCOOH, CO, and CO(2) and was incomplete due to catalyst deactivation by nonvolatile products. In the second scenario of air purification, DMMP underwent adsorption, hydrolysis, and photooxidation at the same time. It resulted in the quickest removal of DMMP from the gas phase and completion of oxidation in 30 min, suggesting this process for practical air decontamination. At least 0.8 nm(2) of TiO(2) surface per each DMMP molecule should be available for complete purification of air.
在静态条件下，采用傅里叶变换红外光谱（FTIR）技术，对高比表面积锐钛矿型TiO₂在室温下对甲基膦酸二甲酯（DMMP）的空气去除和分解进行了定量研究。在空气净化的第一种情况下，DMMP经历了反应吸附，吸附完成后接着进行光催化氧化。DMMP以外部扩散的速度在TiO₂表面被捕获。吸附的DMMP水解生成甲醇和甲基膦酸甲酯（MMP）。在低DMMP覆盖量时，在1%相对湿度（RH）下它完全水解形成完全表面结合的甲醇，在50%RH下大部分为气态甲醇。光催化氧化产生唯一的含碳气态产物CO₂和双齿甲酸盐作为中间表面产物。在高DMMP覆盖量时，它捕获不完全且仅在气相中部分水解生成CH₃OH，50%RH促进了这两个过程。光催化氧化产生气态HCOOH、CO和CO₂，并且由于非挥发性产物使催化剂失活，氧化不完全。在空气净化的第二种情况下，DMMP同时进行吸附、水解和光氧化。这导致DMMP从气相中去除最快，并在30分钟内完成氧化，表明该过程可用于实际空气净化。每个DMMP分子至少需要0.8 nm²的TiO₂表面才能完全净化空气。
