Increased Hydrogenation Rates in Pd/La-Al₂O₃ Catalysts by Hydrogen Transfer O(-La) Sites Adjacent to Pd Nanoparticles

In this study, a simple bottom-up synthesis is presented to introduce atomically dispersed La into Al2O3 followed by the addition of Pd to prepare a microspherical Pd/La-Al2O3 catalyst with potential for hydrogenation applications. The Pd/La-Al2O3 catalyst displays enhanced activity for a number of hydrogenation reactions and functional groups, for example, C═O, C═C, C═N, and aromatic rings. Incorporation of O(-La) sites adjacent to Pd nanoparticles (NPs) is suggested to reversibly transfer and store catalytically active hydrogen at the O(-La) site. A kinetic analysis of 2-ethylanthraquinone (EAQ) hydrogenation shows that the H2 reaction order drops from one for Pd/Al2O3 to zero for Pd/La-Al2O3, while the EAQ order remains unchanged. Incorporation of isolated O(-La) sites adjacent to the Pd NPs provides a feasible strategy for the design of high-efficiency hydrogenation catalysts and has important implications for the development of the commercial hydrogenation process.