As part of an ongoing effort to understand the deactivation and improve the stability of metal oxide-supported Au catalysts in the low-temperature CO oxidation reaction while maintaining their high activity, we have investigated the influence of a mesoporous silica SBA-15 substrate on the activity and stability of Au/TiO₂ catalysts, which consist of a SBA-15 support surface modified by a monolayer of TiO_x with Au nanoparticles on top. The extent of the TiO_x surface modification was systematically increased, while the Au loading and the Au particle sizes were largely kept constant. Employing kinetic measurements at three different temperatures (30 °C, 80 °C, 180 °C) and a number of ex situ methods as well as in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for catalyst characterization, we found that the activity of these catalysts increases significantly with the Ti concentration and with reaction temperature. The tendency for deactivation remains essentially unchanged. Detailed in situ DRIFTS measurements reveal that the Au nanoparticles are largely formed on the TiO_x surface-modified areas of the SBA-15 support and that the tendency for surface carbonate formation is very low. The observed deactivation may at least partly be related to the accumulation of molecularly adsorbed H₂O species, in particular at low temperatures (30 °C). These are likely to be formed from surface hydroxyl groups, they may affect the reaction either by blocking of active sites or by blocking the adsorption of reactants on the substrate. Other effects, such as reaction induced changes in the titania layer, must however, play a role as well, both at 80 °C and in particular at 180 °C, where accumulation of adsorbed species is negligible. The mechanistic ideas are supported by reactivation tests subsequent to calcination at 400 °C, which were found to fully restore the initial activity.

为了解低温金属氧化负载的金催化剂在高温CO氧化反应中的失活并提高其稳定性并同时保持其高活性的不懈努力的一部分，我们研究了介孔二氧化硅SBA-15底物对该催化剂的影响。 Au / TiO ₂催化剂的活性和稳定性，该催化剂由SBA-15载体表面组成，该载体表面被TiO _x单层改性，顶部具有Au纳米颗粒。TiO _x表面改性的程度有系统地增加，而Au的含量和Au的粒径基本保持恒定。在三个不同温度（30°C，80°C，180°C）和一些采用动力学测量易地方法以及原位漫反射红外傅里叶变换光谱（DRIFTS）用于催化剂表征，我们发现这些催化剂的活性随Ti浓度和反应温度而显着增加。失活的趋势基本上保持不变。详细的原位DRIFTS测量表明，Au纳米粒子主要形成在SBA-15载体的TiO _x表面改性的区域上，并且表面碳酸盐形成的趋势非常低。观察到的失活可能至少部分与分子吸附的H ₂的积累有关O种，尤其是在低温（30°C）下。这些可能是由表面羟基形成的，它们可能通过封闭活性位点或封闭反应物在底物上的吸附而影响反应。然而，其他效应，例如反应引起的二氧化钛层的变化，也必须在80°C尤其是180°C时发挥作用，在这些情况下，被吸收物质的积累可忽略不计。在400°C下煅烧后，通过重新活化试验来支持机理学思想，发现该试验可完全恢复其初始活性。