Chemical Vapor Deposition of Al13 Fe4 Highly Selective Catalytic Films for the Semi-Hydrogenation of Acetylene

Abstract

Catalytic properties of coatings containing the Al13Fe4 intermetallic phase are tested in the reaction of semi-hydrogenation of acetylene. The selectivity to ethylene is found as high as 74% close to the reported values for pure,unsupported Al13Fe4. The initial conversion of acetylene to ethylene is 84% and rapidly drops due to the catalytic formation of carbon-based by-products on secondary Al-Fe phases. Coatings are processed through sequential chemical vapor deposition (CVD) of aluminum (5 Torr, 180 °C) and iron(40 Torr, 140 °C) layers, followed by in situ annealing for 60 min at 575 °C.Deposition proceeds at high growth rate, resulting in 15 μm thick films. After annealing, coatings are composed of the Al13Fe4 phase, co-existing with minor secondary Al-Fe intermetallic phases. Overall, it is shown that films containing complex Al-Fe intermetallic phases can be processed by CVD, opening new routes to the engineering of pure, supported Al13Fe4 catalysts on 3D or porous supports.