Institute for Applied and Physical Chemistry and ‡Institute for Organic and Analytical Chemistry, University of Bremen , Leobenerstraße, 28359 Bremen, Germany.
J Am Chem Soc. 2015 Jan 21;137(2):905-12. doi: 10.1021/ja511349p. Epub 2015 Jan 8.
In this work we present the successful application of functionalizing Pt nanoparticles (NPs) with hydrophilic organic ligands as a strategy for enhancing their catalytic activity and selectivity. In the first step, Pt NPs were prepared by a colloidal approach and subsequently functionalized in a separate synthesis step with L-proline (PRO). The functionalized NPs were supported onto Al2O3 and investigated as heterogeneous catalysts for the selective hydrogenation of acetophenone. Whereas significant amounts of side products are formed by supported, "unprotected" (ligand-free) NPs, the PRO-functionalized Pt NPs are highly chemoselective even at 100% conversion. Experiments under kinetically controlled conditions reveal that this high chemoselectivity is not accompanied by a loss of catalytic activity. In contrast, an enhanced rate toward the desired product was found for PRO-Pt in comparison to the "unprotected" Pt NPs. This finding demonstrates that the use of ligands in heterogeneous catalysis allows for simultaneous enhancements of activity and selectivity.
在这项工作中，我们成功地应用了功能化 Pt 纳米粒子（NPs）与亲水性有机配体，作为提高其催化活性和选择性的策略。在第一步中，通过胶体方法制备 Pt NPs，然后在单独的合成步骤中用 L-脯氨酸（PRO）对其进行功能化。将功能化的 NPs 负载到 Al2O3 上，并作为苯乙酮选择性加氢的多相催化剂进行研究。虽然负载的“无保护”（无配体）NPs 会形成大量副产物，但 PRO 功能化的 Pt NPs 即使在 100%转化率下也具有很高的化学选择性。在动力学控制条件下的实验表明，这种高化学选择性不会伴随着催化活性的降低。相比之下，与“无保护”的 Pt NPs 相比，PRO-Pt 对所需产物的反应速率有所提高。这一发现表明，在多相催化中使用配体可以同时提高活性和选择性。
