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.

Silica-Confined Pt3Sn Clusters for Propane Dehydrogenation

“…For the Pt@SiO 2 sample, hydrogen consumptions at 273, 500, and 563 K represented the reductions of PtO x in particles, clusters, and isolated species, respectively . Sn addition modified the reduction property considerably, with an additional hydrogen consumption at 753 K for the reduction of SnO x to metallic Sn. , H 2 -TPR of a reference SnO 2 @SiO 2 sample showed broad hydrogen consumption at 423–873 K, verifying a sequential process, i.e., Sn 4+ to Sn 2+ and then to Sn 0 . For the Pt 0.8 Sn 0.2 @SiO 2 sample, the peak at 598 K was most likely associated with the reduction of SnO 2 (Sn 4+ → Sn 2+ ) interacting with Pt species.…”

Copper-Promoted Platinum Supported on HSSZ-13 Zeolite Catalysts for Propane Dehydrogenation to Propylene

“…The addition of Zr increased the lattice oxygen on the molecular sieve surface, regulated the acidity of the catalysts, and improved the selectivity of propylene . In addition to ZSM-5, some mesoporous zeolites such as SBA-15, , MCM-41, , MCM-48, and silicalite-1 , also serve as support for PDH catalysts. SSZ-13 is a zeolite that has a three-dimensional porous structure and eight-membered rings with a CHA structure. , Because of its uniform channel and acidity, SSZ-13 is usually used for the separation of CO 2 from natural gas and as the catalyst for methanol to olefins (MTO) .…”

Structure Robustness of Highly Dispersed Pt/Al2O3 Catalyst for Propane Dehydrogenation during Oxychlorination Regeneration Process

“…Recently, some highly dispersed (single-atom, cluster or subnanosized) Pt catalysts with enhanced metal-support interactions were reported to be effective PDH catalysts, showing low deactivation rates and good structural stability [11][12][13][14][15][16][17]. However, it should be noted that these catalysts are usually tested under a reaction temperature below 600 • C, which is lower than the industrial PDH reactor inlet temperature.…”