title: Role of Sn in the Regeneration of Pt/γ-Al2O3Light Alkane Dehydrogenation Catalysts.
abstract: Alumina-supported Pt is one of the major industrial catalysts for light alkane dehydrogenation. This catalyst loses activity during reaction, with coke formation often considered as the reason for deactivation. As we show in this study, the amount and nature of carbon deposits do not directly correlate with the loss of activity. Rather, it is the transformation of subnanometer Pt species into larger Pt nanoparticles that appears to be responsible for the loss of catalytic activity. Surprisingly, a portion of the Sn remains atomically dispersed on the alumina surface in the spent catalyst and helps in the redispersion of the Pt. In the absence of Sn on the alumina support, the larger Pt nanoparticles formed during reaction are not redispersed during oxidative regeneration. It is known that Sn is added as a promoter in the industrial catalyst to help in achieving high propene selectivity and to minimize coke formation. This work shows that an important role of Sn is to help in the regeneration of Pt, by providing nucleation sites on the alumina surface. Aberration-corrected scanning transmission electron microscopy helps to provide unique insights into the operating characteristics of an industrially important catalyst by demonstrating the role of promoter elements, such as Sn, in the oxidative regeneration of Pt on γ-Al2O3.
authors.affiliation: Department of Chemical & Biological Engineering and Center for Microengineered Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States.
authors.forename: Hien N
authors.initials: HN
authors.lastname: Pham
authors.affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Jesper J H B
authors.initials: JJ
authors.lastname: Sattler
authors.affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Bert M
authors.initials: BM
authors.lastname: Weckhuysen
authors.affiliation: Department of Chemical & Biological Engineering and Center for Microengineered Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States.
authors.forename: Abhaya K
authors.initials: AK
authors.lastname: Datye
keywords: Pt-Sn/γ-Al2O3; Pt/γ-Al2O3; STEM/HRTEM; coking; nucleation sites; oxidative regeneration; propane dehydrogenation; sintering