Theoretical Study on Propane Dehydrogenation Reaction Over PtxSny Intermetallic Compounds

Abstract

PtxSny intermetallic compounds are widely used catalysts in the propane dehydrogenation reaction(PDH). However, the relationships between their composition, structure and PDH performance remain unclear. In this study, the effects of PtSn catalysts (Pt3Sn, Pt1Sn1, Pt2Sn3) and pure Pt on propane dehydrogenation (PDH) with different Pt/Sn ratios are compared and studied by using density functional theory. The results show that with the increase of Sn content, the electron density of Pt increased, thereby reducing the adsorption of propylene on the catalyst surface, and this electronic effect improves the selectivity of propylene. As the Sn content increases, the generalized coordination number() decreases, and the propylene selectivity increases, while moderate surface roughness(R) aids for the desorption of propylene. By comparing the energy barrier (Pt1Sn1(110)(1.452 eV) > Pt2Sn3(110)(1.248 eV) > Pt3Sn(111)(0.628 eV) > Pt(111)(0.535 eV)) and selectivity parameters (Ediff) (Pt2Sn3(110)(0.965 eV) > Pt1Sn1(110)(0.368 eV) > Pt3Sn(111)(0.116 eV) > Pt(111)(-0.893 eV)), the intermetallic compounds Pt3Sn and Pt2Sn3 can both serve as candidate catalysts for propane dehydrogenation. This is consistent with the experimental results. This work provides a theoretical information for the rational design of high-performance Pt-based intermetallic compound catalysts for the PDH reaction.