On the Role of Sn Segregation of Pt-Sn Catalysts for Propane Dehydrogenation

Abstract

Bimetallic nanoparticle catalysts attract extensive attention for relevant catalysis processes due to their flexible structures, while the structure evolution under specific conditions is ambiguous. This paper describes the structure evolution of Pt-Sn bimetallic nanoparticles for catalytic dehydrogenation, especially Sn segregation for surface recovery of a Pt-Sn alloy. An acid etching-reduction process was adopted to investigate the migration of Sn atoms after surface Sn species loss. By acid etching, Sn atoms at the surface of Pt-Sn alloy nanoparticles were removed, leaving nanoparticles with a Pt-rich shell and an unchanged Pt 3 Sn alloy core. Excitedly, during the following reduction process, the Pt 3 Sn alloy surface was recovered due to the migration of Sn atoms from the core to the surface, as confirmed by transmission electron microscopy, quasi in situ X-ray photoelectron spectroscopy, and density functional theory calculations. Subsequent studies on the catalyst performance for propane dehydrogenation (PDH) showed that the recoverable Pt 3 Sn alloy surface structure contributed to the high efficiency with 92% propene selectivity even after 5 cycles of the acid etchingreduction procedure. The recovery of the Pt-Sn alloy through Sn segregation could enable catalysts to overcome component fluctuations, making an efficient catalytic process.

Selenium-Rich Configuration and Amorphization for Synergistically Maximizing the Active-Center Amount of CoSe1+x Nanodots toward Efficient Photocatalytic H2 Evolution

“…Sustainable H 2 production by photocatalysis is a green and environmentally friendly candidate to meet the global energy shortage. − However, single photocatalysts still suffers from serious recombination of photogenerated charges, which severely impedes further practical applications. − To solve the above problems and realize efficient photocatalytic activity, different strategies have been explored involving construction of a heterojunction, , cocatalyst modification, , and morphology engineering. , Among them, integrating cocatalysts has been proven to be a versatile means to dramatically boost the photocatalytic activity, which not only can expedite the separation of photoexcited carriers but also minimize the activation energy of H 2 production. − Particularly, platinum group metals have been widely used to enhance the activity of various photocatalytic materials (including TiO 2 , CdS, and g-C 3 N 4 ), , but their exorbitant price and low abundance seriously limit the commercialization process. − Therefore, it is very essential to further explore cheap and highly active hydrogen generation cocatalysts for signally improving the efficiency of water splitting. − …”

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

“…Moreover, the turnover rate increases with the Pt-Sn coordination number, while the higher propylene selectivity was attributed to the geometric effects of Sn in reducing the Pt ensembles. The energy required for Sn atoms to move from the bulk to the surface in a Pt3Sn@Pt model was calculated, demonstrating that the most negative segregation energy happens with a Pt3Sn top layer and four Sn atoms at the surface [22]. Moreover, it has been demonstrated that the Pt3Sn alloy surface can be easily restored by reduction after an acid etching controlled process, showing that the Pt3Sn alloy surface is recoverable and thermodynamically preferable.…”

Dynamics of Heterogeneous Catalytic Processes at Operando Conditions

“…(c) Quasi in situ XPS of Pt–Sn/SBA-15 reduced by H 2 . Reprinted from refs ( 195 ) and ( 196 ). Copyright 2021 American Chemical Society.…”

“…A Pt–Sn alloy is another important system for the dehydrogenation of propane. Combining in situ XPS, TEM, and DFT calculations, Wang et al 195 revealed the phenomena of migration of Sn atoms from the inner core to the surface during a reduction induced by H 2 ( Figure 9 c) and the formation of the Pt–Sn alloy surface structure.…”