Effects of Dopants in PtSn/M‐Silicalite‐1 on Structural Property and on Catalytic Propane Dehydrogenation Performance

Abstract

The various metal-doped Silicalite-1 (MÀ S1, M=Mg, Al, Fe and In) supports were prepared by hydrothermal synthesis method, then were used to disperse the PtSn species through impregnation. The resulting solids were further characterized through XRD, N 2 adsorption/desorption isotherms, XPS, H 2 -TPR, NH 3 -TPD, Raman spectroscopy and TG techniques to investigate the structural property before and after propane dehydrogenation reaction. The results exhibited that the introduction of various metal dopants had profound effects on pore structure, reducibility, acidity and surface content of Pt which was directly related to the activation of propane. And the surface content of Pt acted as the dominant role for converting propane. As a consequence, the maximum initial conversion of propane was obtained over Fe-modified PtSn/FeÀ S1 sample, but it deactivated fast as well because of the coke deposition.

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

“…For the Pt/S-1 sample, there was a broad and weak reduction peak at 280 °C that could be assigned to the reduction of Pt oxide species interacting with S-1 . For 20SnO 2 /S-1, two reduction peaks were generated: the peak at 250 °C was attributed to the reduction of Sn 4+ to Sn 2+ , while the peak at 450 °C clearly indicated the reduction of Sn 4+ or Sn 2+ to Sn 0 . The reduction peaks of Pt/20SnO 2 /S-1, Pt/20TDMASn/S-1, and Pt/200TDMASn/S-1 appeared at 320, 350, and 380 °C, respectively, which can be attributed to the reduction of Pt and Sn species .…”

“…32 For 20SnO 2 /S-1, two reduction peaks were generated: the peak at 250 °C was attributed to the reduction of Sn 4+ to Sn 2+ , while the peak at 450 °C clearly indicated the reduction of Sn 4+ or Sn 2+ to Sn 0 . 33 The reduction peaks of Pt/20SnO 2 /S-1, Pt/ 20TDMASn/S-1, and Pt/200TDMASn/S-1 appeared at 320, 350, and 380 °C, respectively, which can be attributed to the reduction of Pt and Sn species. 34 Compared with the peak of Pt/20SnO 2 /S-1, the reduction peak of Pt/20TDMASn/S-1 appeared at a higher temperature, demonstrating that the interaction between the metal species and the support was stronger.…”

“…Among the three catalysts, the Pt/20TDMASn/S-1 catalyst showed the highest initial propane conversion (36.46%) because it had the highest content of Pt 0 to provide active sites in the PDH process. 33 There may be two reasons that the initial propane conversion of Pt/20SnO 2 /S-1 (9.28%) was lower than that of Pt/20TDMASn/S-1 (36.46%). The first was that the particle size (3.7 nm) of Pt/20SnO 2 /S-1 was larger than that of Pt/20TDMASn/S-1 (2.7 nm), resulting in a large reduction of active sites.…”

Propylene Synthesis: Recent Advances in the Use of Pt-Based Catalysts for Propane Dehydrogenation Reaction

“…of Cs + ions into the zeolite is able to improve the regeneration of the catalyst, without affecting the catalytic activity [73]. Various metals have been used to dope silicalite-1 (M-S1, M = Mg, Al, Fe and In), and the corresponding PtSn/M-S1 catalysts showed the micro-and mesoporous hybrid structure feature [74]. The addition of the metal elements significantly affected the catalyst acidity and reducibility, increasing the hydrogen consumption due to the enhanced reduction of Pt and Sn oxides.…”

“…Hexagonal boron nitride nanosheet supported Pt/Cu cluster catalysts are able to disperse and stabilize Pt/Cu clusters; the fault edges of the h-BN nanosheets and the strong interaction between Cu and B-O edge defects stabilizes the unique geometry and elec- Various metals have been used to dope silicalite-1 (M-S1, M = Mg, Al, Fe and In), and the corresponding PtSn/M-S1 catalysts showed the micro-and mesoporous hybrid structure feature [74]. The addition of the metal elements significantly affected the catalyst acidity and reducibility, increasing the hydrogen consumption due to the enhanced reduction of Pt and Sn oxides.…”