Aiming at a better mechanistic understanding of Mars-van Krevelen type catalytic reactions, we have systematically investigated possible correlations between the composition of the reaction gas atmosphere, the concentration of surface oxygen vacancies (surface oxidation state), and the catalytic activity of a Au/TiO₂ catalyst in the CO oxidation reaction. In the meantime, there is considerable experimental and theoretical evidence that this reaction follows a Au-assisted Mars-van Krevelen mechanism at reaction temperatures ≥80 °C. Employing quantitative pulse experiments in a temporal analysis of products (TAP) reactor we found that both the surface oxidation state and the activity of the catalyst under steady-state conditions depend sensitively on the composition of the reaction gas atmosphere, specifically on the CO:O₂ ratio, and that there is a strict correlation between these quantities. A simple kinetic model is introduced, which allows to quantitatively determine the ratio of the effective reaction rate constants for reduction and oxidation of the TiO₂ support surface. These results and ideas are considered to be of general relevance for the understanding of Mars-van Krevelen type reactions and specifically of oxidation reactions on supported Au catalysts, and they lend further support to previous proposals of a Au-assisted Mars-van Krevelen mechanism for this reaction.

为了更好地了解Mars-van Krevelen型催化反应的机理，我们系统地研究了反应气体气氛的组成，表面氧空位浓度（表面氧化态）与Au /二氧化钛₂催化剂在CO氧化反应中。同时，有大量的实验和理论证据表明，该反应在≥80°C的温度下遵循金辅助的Mars-van Krevelen机理。通过在产品时间分析（TAP）反应器中进行定量脉冲实验，我们发现表面氧化态和稳态条件下催化剂的活性都敏感地取决于反应气体气氛的组成，特别是取决于CO：O _2个比率，并且这些量之间存在严格的相关性。介绍了一个简单的动力学模型，该模型可以定量确定用于TiO ₂还原和氧化的有效反应速率常数的比值支撑面。这些结果和思想被认为与理解Mars-van Krevelen型反应特别是在负载型Au催化剂上的氧化反应具有普遍意义，并且它们进一步支持了Au辅助的Mars-van Krevelen机理的先前提议。这个反应。