Modulating the spatial locations of bimetallic sites in KL zeolite via atomic layer deposition for improved n-heptane aromatization

• A strategy for spatial control of Pt and Sn on KL zeolite was developed. • Sn in zeolite framework enables selective Pt deposition in channels. • Sn on zeolite surface inhibits Pt from entering pores. • Pt-Sn in channels shows higher toluene selectivity and enhanced stability. • DFT calculations correlated the bimetallic site location with C–H bond activation. The spatial distribution of bimetallic species within and outside zeolite channels plays a critical role in determining their catalytic performance. Despite zeolites being widely recognized as ideal scaffolds for stabilizing bimetallic catalysts, achieving precise control over metal positioning remains a challenge, which limits their application in heterogeneous catalysis. Here, we developed a strategy to precisely control the spatial location of platinum (Pt) and tin (Sn) in KL zeolite using atomic layer deposition (ALD). By incorporating Sn into the zeolite framework, we enabled selective deposition of Pt within the channels through the enhanced interaction between Sn species and the Pt precursor. In contrast, Sn introduced at the external surface and pore openings was used to restrict Pt deposition to the external surface. This approach allowed us to produce catalysts with distinct Pt and Sn distributions, enabling a direct comparison of their catalytic properties. The Pt and Sn species confined within the zeolite channels showed high reactivity in n -heptane aromatization, achieving excellent toluene selectivity and improved stability. Density functional theory (DFT) calculations showed that the Pt-Sn sites within the channels efficiently activated the C–H bonds of n -heptane, facilitating dehydrocyclization and aromatic formation. This work provides a robust method for precise bimetallic spatial control, offering a new avenue for optimizing catalyst design and advancing the field of heterogeneous catalysis.