The gas-phase epoxidation of propylene with H/O is a promising method to generate propylene oxide (PO). Au/TS-1 is preferred catalyst due to the synergistic effect between Au nanoparticles and framework Ti species. TS-1 with high Ti content are used as support for Au catalysts, which are expected to achieve fantastic catalytic performance. However, their actual catalytic properties are generally unsatisfactory. The reason for this phenomenon is that the role of TiO in Ti-containing support is unclear. Here, we found that increasing TiO content in Ti-containing supports offered improving isoelectric point (IEP), which could be responsible for the obviously enhanced Au loading. More Au nanoparticles inserted into the TS-1 micropore favors their cooperation with framework Ti sites to realize higher CH conversion. Simultaneously, propanal generated via direct propylene oxidation catalyzed by Au/TiO leads to the decrease of PO selectivity. A volcanic-shaped relationship between TiO content and PO formation rate is emerged.

中文翻译：

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TiO2对金钛催化丙烯气相环氧化反应性能的影响

丙烯与 H/O 的气相环氧化是生成环氧丙烷 (PO) 的一种有前途的方法。由于 Au 纳米粒子和骨架 Ti 物种之间的协同效应，Au/TS-1 是优选的催化剂。采用高Ti含量的TS-1作为Au催化剂的载体，有望实现优异的催化性能。然而，它们的实际催化性能普遍不能令人满意。造成这种现象的原因是TiO在含Ti载体中的作用尚不清楚。在这里，我们发现增加含钛载体中的 TiO2 含量可以提高等电点（IEP），这可能是金负载量明显增加的原因。更多的Au纳米颗粒插入TS-1微孔中，有利于它们与骨架Ti位点的合作，以实现更高的CH转化率。同时，Au/TiO催化丙烯直接氧化生成丙醛导致PO选择性降低。 TiO 含量和 PO 形成速率之间出现了火山形关系。