Combustion of acetylene over the mesoporous CeO2-supported IrFe bimetallic catalysts

Abstract Bimetallic compounds are a kind of important catalytic materials in heterogeneous catalysis. In this work, we first employed n-butyllithium as reducing agent to synthesize Ir and IrFex (x is the Fe/Ir molar ratio and equal to 0.49, 0.90, and 2.80) nanocrystals (NCs), and then used an adsorption strategy to load them on the surface of ordered mesoporous ceria (meso-CeO2) derived from the KIT-6-templating route to obtain the 0.48 wt% Ir/meso-CeO2 (denoted as 0.48Ir/meso-CeO2) and 0.53–0.89 wt% IrFex/meso-CeO2 (denoted as 0.53IrFe0.49/meso-CeO2, 0.59IrFe0.90/meso-CeO2, and 0.89IrFe2.80/meso-CeO2) samples. Physicochemical properties of the samples were characterized by means of various techniques. It is shown that all of the samples possessed a cubic crystal phase, an ordered mesoporous architecture, and a surface area of 84–124 m2/g, in which the IrFex NCs with an average size of ca. 2 nm were highly dispersed on the meso-CeO2 surface. Among all of the samples, 0.59IrFe0.90/meso-CeO2 performed the best for acetylene combustion (T10% =155 °C, T50% =162 °C, and T90% =165 °C at space velocity = 20,000 mL/(g h)). Furthermore, 0.59IrFe0.90/meso-CeO2 showed good water- and carbon dioxide-resistant performance, and its partial deactivation due to the introduction of SO2 was reversible. The possible reaction mechanisms over Ir/meso-CeO2 or IrFex/meso-CeO2 were also discussed. We conclude that the well dispersed IrFe0.90 NCs, high adsorbed oxygen and acetylene amounts, low-temperature reducibility, and strong interaction between IrFe0.90 NCs and meso-CeO2 were responsible for the good catalytic performance of 0.59IrFe0.90/meso-CeO2.