Deciphering the role of (metal–)support on the reductive amination of levulinates

Abstract

Biomass-derived levulinic acid (LevuA) and its esters are key intermediates for producing high-value pyrrolidones, such as N-substituted-5-methyl-2-pyrrolidones (NSMPs), through reductive amination. These compounds have promising applications in industries ranging from petrochemicals and polymers to pharmaceuticals, agrochemicals, and textiles. Significant research has focused on developing catalytic systems using both precious (e.g., Pt, Pd and Rh) and non-precious metals, which are highly active due to their efficient H₂ activation and intermediate activation properties. However, the catalytic performance of these metals can vary significantly depending on the nature of the support material. Understanding the behaviour of supported metal, the properties of the support, and their interaction is crucial for optimising reductive amination processes. This review examines the roles of both precious and non-precious metals in intermediate and H₂ activation on the catalyst surface. It also explores how the intrinsic properties of the supports – such as acidic, basic and neutral characteristics – affect catalytic performance. Key factors like the formation of frustrated Lewis pair (FLP), surface acidity, and structural features (e.g., morphology, exposed facets and particle size) are discussed to comprehensively understand their influence on the catalytic process. Finally, the review concludes with an analysis of the current challenges and perspectives, highlighting the need for further development of efficient, stable, and industrially viable catalytic materials for the reductive amination of bio-based carbonyls.