Abstract：
Platinum-based supported intermetallic alloys (IMAs) demonstrate exceptional performance in catalytic propane dehydrogenation (PDH) primarily because of their remarkable resistance to coke formation. However, these IMAs still encounter a significant hurdle in the form of catalyst deactivation. Understanding the complex deactivation mechanism of supported IMAs, which goes beyond conventional coke deposition, requires meticulous microscopic structural elucidation. In this study, we unravel a nonclassical deactivation mechanism over a PtZn/γ-Al2O3 PDH catalyst, dictated by the PtZn to Pt3Zn nanophase transformation accompanied with dezincification. The physical origin lies in the metal support interaction (MSI) that enables strong chemical bonding between hydroxyl groups on the support and Zn sites on the PtZn phase to selectively remove Zn species followed by the reconstruction towards Pt3Zn phase. Building on these insights, we have devised a solution to circumvent the deactivation by passivating the MSI through surface modification of γ-Al2O3 support. By exchanging protons of hydroxyl groups with potassium ions (K) on the γ-Al2O3 support, such a strategy significantly minimizes the dezincification of PtZn IMA via diminished metal-support bonding, which dramatically reduces the deactivation rate from 0.2044 to 0.0587 h-1.
摘要：
铂基负载的金属间合金（IMAs）在催化丙烷脱氢（PDH）中表现出出色的性能，这主要是因为它们具有出色的抗焦炭形成能力。然而,这些IMA仍然遇到催化剂失活形式的重大障碍。了解受支持的IMA的复杂停用机制，这超越了传统的焦炭沉积，需要细致的微观结构阐明。在这项研究中,我们揭示了PtZn/γ-Al2O3PDH催化剂上的非经典失活机理，由PtZn到Pt3Zn纳米相转化伴随脱锌作用决定。物理起源在于金属载体相互作用(MSI),其使得载体上的羟基与PtZn相上的Zn位点之间的强化学键合以选择性地去除Zn物质,随后向Pt3Zn相重构。基于这些见解，我们设计了一种解决方案，通过对γ-Al2O3载体进行表面改性来钝化MSI来避免失活。通过将羟基的质子与γ-Al2O3载体上的钾离子（K）交换，这样的策略通过减少金属-支撑结合显著地最小化PtZnIMA的脱锌,这将失活速率从0.2044大大降低到0.0587h-1。
