Balancing micro-/mesoporosity in Pt/KL zeolite catalysts for n-heptane aromatization

1,2,6-Hexanetriol tailors KL zeolites with varied micro-/mesopore ratios. • ALD introduces Pt species into both microporous and mesoporous KL regions • A balanced micro-/mesopore architecture promotes toluene production. • An optimized pore architecture suppresses the formation of isomers. The pore architecture of KL zeolite plays a critical role in linear alkane aromatization over Pt-based catalysts. However, how the interplay between microporous confinement and mesopore-enabled diffusion regulates Pt species and the subsequent formation of aromatics remains insufficiently understood. Herein, 1,2,6-hexanetriol was selected as a zeolite growth modifier to tailor the porous structure of KL zeolite with varied micro-/mesopore ratios. Pt species were then introduced into the KL zeolites by atomic layer deposition, affording a series of Pt/KL catalysts in which Pt species were distributed in both microporous and mesoporous regions. The Pt/KL-T 1 catalyst with a mesopore-to-micropore volume ratio of 1.2 gave an enhanced toluene formation rate (7.6 × 10 2 mmol Toluene ·g Pt –1 ·h –1 ), which was approximately twice that of the purely microporous Pt/KL catalyst. Combined structural characterizations and molecular dynamics simulations indicated an appropriate balance between micropore and mesopore facilitates the diffusion and further dehydrocyclization of alkene (σC 7 = ) intermediates, while suppressing isomer formation. These findings clarify the balance of micro- and mesoporosity in KL zeolite and provide a strategy to tune Pt/KL-based catalysts for alkane aromatization. Download: Download high-res image (190KB) Download: Download full-size image