Arsac F, Bianchi D, Chovelon J M, Ferronato C, Herrmann J M
Laboratoire d'Application de la Chimie à l'Environnement (LACE), UMR 5634, Université Claude Bernard, Lyon-1, Bat. Raulin, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne-France.
J Phys Chem A. 2006 Mar 30;110(12):4202-12. doi: 10.1021/jp055342b.
The present study concerns an experimental microkinetic approach of the photocatalytic oxidation (PCO) of isopropyl alcohol (IPA) into acetone on a pure anatase TiO2 solid according to a procedure previously developed. Mainly, the kinetic parameters of each surface elementary step of a plausible kinetic model of PCO of IPA are experimentally determined: natures and amounts of the adsorbed species and rate constants (preexponential factor and activation energy). The kinetics parameters are obtained by using experiments in the transient regime with either a FTIR or a mass spectrometer as a detector. The deep oxidation (CO2 and H2O formation) of low concentrations of organic pollutants in air is one of the interests of the PCO. For IPA, literature data strongly suggest that acetone is the single route to CO2 and H2O and this explains that the present study is dedicated to the elementary steps involving gaseous and adsorbed C3H(x)O species. The microkinetic study shows that strongly adsorbed IPA species (two species denoted nd-IPA(sads) and d-IPA(sads) due to non- and dissociative chemisorption of IPA, respectively) are involved in the PCO of IPA. A strong competitive chemisorption between IPA(sads) and a strongly adsorbed acetone species controls the high selectivity in acetone of the PCO at a high coverage of the surface by IPA(sads). The kinetic parameters of the elementary steps determined in the present study are used in part 2 to provide a modeling of macroscopic kinetic data such as the turnover frequency (TOF in s(-1)) of the PCO using IPA/O2 gas mixtures.
本研究涉及一种实验微观动力学方法，该方法是根据先前开发的程序，在纯锐钛矿型TiO₂固体上将异丙醇（IPA）光催化氧化（PCO）为丙酮。主要通过实验确定IPA光催化氧化可能的动力学模型中每个表面基元步骤的动力学参数：吸附物种的性质和数量以及速率常数（指前因子和活化能）。动力学参数是通过使用傅里叶变换红外光谱仪（FTIR）或质谱仪作为检测器的瞬态实验获得的。空气中低浓度有机污染物的深度氧化（生成CO₂和H₂O）是光催化氧化的研究热点之一。对于IPA，文献数据有力地表明丙酮是生成CO₂和H₂O的唯一途径，这也解释了本研究致力于涉及气态和吸附态C₃H(x)O物种的基元步骤。微观动力学研究表明，强吸附的IPA物种（由于IPA的非解离和解离化学吸附分别产生的两种物种，记为nd - IPA(sads)和d - IPA(sads)）参与了IPA的光催化氧化。在IPA(sads)对表面具有高覆盖率时，IPA(sads)与强吸附的丙酮物种之间的强竞争性化学吸附控制了光催化氧化对丙酮的高选择性。本研究中确定的基元步骤的动力学参数在第2部分中用于对宏观动力学数据进行建模，例如使用IPA/O₂气体混合物时光催化氧化的周转频率（TOF，单位为s⁻¹）。
