Delivering a Modifying Element to Metal Nanoparticles via Support: Pt–Ga Alloying during the Reduction of Pt/Mg(Al,Ga)Ox Catalysts and Its Effects on Propane Dehydrogenation

Abstract

The alloying of Pt with Ga delivered from a hydrotalcite-like support was investigated as a strategy to produce bimetallic catalysts for propane dehydrogenation. A series of Pt/Mg(Al,Ga)Ox catalysts (2–3 wt % Pt, Ga/Pt molar ratios between 0 and 10) and a model Pt/Ga2O3 catalyst (4 wt % Pt, Ga/Pt molar ratio of 50) were characterized by means of X-ray diffraction (XRD), transmission electron microscopy, and activity measurements (873 K, Wcat/FC3H8,0 = 25 kgcat·s·mol–1 and PC3H8,0 = 5 kPa at a total pressure of 101.3 kPa). XRD patterns taken during temperature-programmed reduction in 5% H2/He and isothermal reduction/oxidation cycling between 5% H2/He and 20% O2/N2 at 873 K revealed dynamic alloy formation and segregation that depended upon the gas environment and Ga content. Alloying on the Pt/Mg(Al,Ga)Ox catalyst with a Ga/Pt ratio of 2 could not be observed by XRD. For a Ga/Pt ratio of 10, an alloy with a diffraction peak at 40.2° was formed during the initial reduction. After subsequent reduction/oxida...