Small-Molecule Modification Provides Pt Nucleation Sites for Enhanced Propane Dehydrogenation Performance

Abstract

The rational synthesis of catalysts with controllable structures and the study of their structure–activity relationships to break the limitations of traditional catalysts remain challenging. Herein, tetrakis(dimethylamido)tin (TDMASn) exposures were used to modify silicalite-1 (S-1) lacking suitable chemisorption sites on their surfaces to provide Pt nucleation sites, obtaining a Pt/20TDMASn/S-1 sample. For comparison, Pt species supported on bare S-1 (Pt/S-1) and Pt species supported on the S-1 of pre-deposited SnO2 (Pt/20SnO2/S-1) were also prepared. Catalysts were characterized extensively by X-ray diffraction, temperature-programmed reduction, transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse-reflectance infrared Fourier transform spectroscopy of adsorbed CO. The results showed that this surface modification (TDMASn or SnO2) yielded up to about a 40-times increase in Pt content after 20 cycles of Pt atomic layer deposition (ALD). Compared with Pt/20SnO2/S-1, Pt/20TDMASn/S-1 had a smaller particle size, stronger interactions between the metal species and the support, and a lower Sn0 content, thus resulting in a remarkably higher initial propane conversion in the propane dehydrogenation (PDH) reaction. The catalytic activity could also be optimized based on the number of ALD-TDMASn exposures. As a consequence, Sn not only provided nucleation sites for Pt but also acted as a promoter to enhance the catalyst performance. This fundamental understanding will help researchers obtain suitable catalysts for PDH processes.