Ligand assisted hydrogenation of levulinic acid on Pt(111) from first principles calculations

In this study, we investigate the hydrogenation reaction of levulinic acid to 4-hydroxypentanovic acidon a ligand-modified Pt(111) using DFT. Modifying nanoparticle surfaces with ligands can havebeneficial effects on the desired reaction such as improved selectivity or lower activation energies.The N3,N3-dimethyl-N2-(quinolin-2-yl)propane-1,2-diamine (AQ) ligand was selected to modify thesurface, since it combines good surface adsorption properties with functional groups that can influencethe reaction. The adsorption geometry of the AQ ligand was studied as well as the co-adsorptionof a second AQ for the possibility of self-assembly. We find that dissociated hydrogen from thePt(111) surface can protonate the AQ ligand and discuss the role this plays on the mechanism ofthe hydrogenation reaction of levulinic acid (LA). By comparing the ligand-modified Pt(111) surfaceto the bare Pt(111) surface we show that the reaction changes from a step-wise to a concertedmechanism due to the influence of the ligand molecule. This demonstrates the effect ligand-modifiedsurfaces can have in catalyzing reactions and shows that desired reactions can be achieved by tuningthe reaction environment.