Platinum is a much used catalyst that, in petrochemical processes, is often alloyed with other metals to improve catalytic activity, selectivity and longevity1-5. Such catalysts are usually prepared in the form of metallic nanoparticles supported on porous solids, and their production involves reducing metal precursor compounds under a H2 flow at high temperatures6. The method works well when using easily reducible late transition metals, but Pt alloy formation with rare-earth elements through the H2 reduction route is almost impossible owing to the low chemical potential of rare-earth element oxides6. Here we use as support a mesoporous zeolite that has pore walls with surface framework defects (called 'silanol nests') and show that the zeolite enables alloy formation between Pt and rare-earth elements. We find that the silanol nests enable the rare-earth elements to exist as single atomic species with a substantially higher chemical potential compared with that of the bulk oxide, making it possible for them to diffuse onto Pt. High-resolution transmission electron microscopy and hydrogen chemisorption measurements indicate that the resultant bimetallic nanoparticles supported on the mesoporous zeolite are intermetallic compounds, which we find to be stable, highly active and selective catalysts for the propane dehydrogenation reaction. When used with late transition metals, the same preparation strategy produces Pt alloy catalysts that incorporate an unusually large amount of the second metal and, in the case of the PtCo alloy, show high catalytic activity and selectivity in the preferential oxidation of carbon monoxide in H2.

中文翻译：

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稀土-铂合金纳米粒子在介孔沸石中的催化作用

铂是一种经常使用的催化剂，在石化过程中，通常与其他金属合金化以提高催化活性、选择性和寿命1-5。这种催化剂通常以负载在多孔固体上的金属纳米粒子的形式制备，它们的生产涉及在高温下在 H2 流下还原金属前体化合物 6。该方法在使用容易还原的晚期过渡金属时效果很好，但由于稀土元素氧化物的化学势低，几乎不可能通过 H2 还原路线与稀土元素形成 Pt 合金6。在这里，我们使用具有表面骨架缺陷（称为“硅烷醇巢”）的孔壁的介孔沸石作为载体，并表明沸石能够在 Pt 和稀土元素之间形成合金。我们发现，与本体氧化物相比，硅烷醇巢使稀土元素能够作为具有显着更高化学势的单一原子物种存在，使它们有可能扩散到 Pt 上。高分辨率透射电子显微镜和氢化学吸附测量表明，负载在介孔沸石上的双金属纳米粒子是金属间化合物，我们发现它们是丙烷脱氢反应的稳定、高活性和选择性催化剂。当与晚期过渡金属一起使用时，相同的制备策略产生的 Pt 合金催化剂包含异常大量的第二种金属，并且在 PtCo 合金的情况下，在 H2 中一氧化碳的优先氧化中显示出高催化活性和选择性.