Chromium oxide is the conventional catalyst for propane direct dehydrogenation. However, the active site and reaction mechanism are still remaining unresolved due to the complicated valence of chromium and co-exists of several active sites. In this work, DFT calculations are performed to reveal the nature of active center and reaction mechanism for the supported chromium catalyst on silica. Three valences of chromium including Cr³⁺, Cr⁵⁺, and Cr⁶⁺ are examined to give a unbiased survey of reactivity. The reaction pathway and C–H activation are carefully examined. Moreover, a detailed analysis of active site regeneration is performed. The reactivities of different oxygen groups attached to Cr including terminal, bridge, and OH group are evaluated at the same footing. Furthermore, the calculations also reveal the intrinsic catalytic properties of chromium which show comparable abilities with oxygen groups. The influence from OH group on support is also evaluated. The comparisons of different reaction pathway give useful indication on the possible reaction mechanism. In the end, the most favorable active site is identified. The current work not only deepen the understanding of catalytic properties of supported chromium catalyst but also supply the doable optimization methods for further improvements.

氧化铬是丙烷直接脱氢的常规催化剂。然而，由于铬的价态复杂，并且几个活性位点并存，因此活性位点和反应机理仍未解决。在这项工作中，进行DFT计算以揭示活性中心的性质和二氧化硅上负载铬催化剂的反应机理。检查了三个价态的铬，包括Cr ³⁺，Cr ⁵⁺和Cr ⁶⁺，以提供无偏性的反应性调查。仔细检查了反应途径和C–H活化。此外，对活动部位再生进行了详细的分析。Cr上不同氧原子的反应性，包括末端，桥键和OH基团在相同的基础上进行评估。此外，该计算还揭示了铬的固有催化性能，该铬具有与氧基团相当的能力。还评估了OH基团对载体的影响。不同反应途径的比较为可能的反应机理提供了有用的指示。最后，确定了最有利的活性部位。当前的工作不仅加深了对负载型铬催化剂催化性能的理解，而且为进一步的改进提供了可行的优化方法。