Sn surface-enriched Pt–Sn bimetallic nanoparticles as a selective and stable catalyst for propane dehydrogenation

• A new synthetic route was developed for the preparation of Pt–Sn nanocatalyst.
• The Sn species enriches specifically the surface of Pt–Sn nanoparticles.
• The Pt–Sn/MgAl2O4 catalyst with high Sn content exhibits good activity in PROX of CO.
• High selectivity and stability were achieved in Pt3.1Sn/MgAl2O4 catalyst for the propane dehydrogenation reaction.
• The excellent performances of Pt–Sn catalysts are associated with the precise deposition of Sn species at the Pt surface.

A new one pot, surfactant-free, synthetic route based on the surface organometallic chemistry (SOMC) concept has been developed for the synthesis of Sn surface-enriched Pt–Sn nanoparticles. Bu3SnH selectively reacts with [Pt]–H formed insitu at the surface of Pt nanoparticles, Pt NPs, obtained by reduction of K2PtCl4 by LiB(C2H5)3H. Chemical analysis, 1H MAS and 13C CP/MAS solid-state NMR as well as two-dimensional double-quantum (DQ) and triple-quantum (TQ) experiments show that organo-tin moieties Sn(n-C4H9) are chemically linked to the surface of Pt NPs to produce, in fine, after removal of most of the n-butyl fragment, bimetallic Pt–Sn nanoparticles. The Sn(n-CH2CH2CH2CH3) groups remaining at the surface are believed to stabilize the as-synthesized Pt–Sn NPs, enabling the bimetallic NPs to be well dispersed in THF. Additionally, the Pt–Sn nanoparticles can be supported on MgAl2O4 during the synthesis of the nanoparticles. Some of the Pt–Sn/MgAl2O4 catalyst thus prepared exhibits high activity in PROX of CO and an extremely high selectivity and stability in propane dehydrogenation to propylene. The enhanced activity in propane dehydrogenation is associated with the high concentration of inactive Sn at the surface of Pt nanoparticles which “isolates” the active Pt atoms. This conclusion is confirmed by XRD, NMR, TEM, and XPS analysis.

Figure optionsDownload high-quality image (208 K)Download as PowerPoint slide