Widening Temperature Window for CO Preferential Oxidation in H<sub>2</sub> by Ir Nanoparticles Interaction with Framework Fe of Hexaaluminate
Bilv Hong, Jinxia Liang, Xiucheng Sun, Ming Tian, Fei Huang, Ying Zheng, Jian Lin, Lin Li, Yanliang Zhou, Xiaodong Wang
Abstract
It is important to develop an efficient noble-metal-based catalyst that has a wide work temperature window and good stability for CO preferential oxidation in H2 (CO-PROX), a key step to purify industrial hydrogen resource. Herein, a catalyst of Fe-substituted hexaaluminate-supported Ir nanoparticles with a mean size of ∼1.4 nm (Ir/BaFeAl11O19) is synthesized. It can exhibit total CO conversion for the CO-PROX reaction in an unprecedented temperature range from 20 to 200 °C, high stability, and good resistance to CO2 and H2O in a simulated practical atmosphere. Detailed characterizations coupled with density functional theory (DFT) calculations show that the interaction between Ir species and framework Fe cations in mirror planes of hexaaluminate promotes the formation of a certain amount (8%) of Fe2+ species for low-temperature CO oxidation, while the Ir species interacting with these Fe2+ provide moderate CO bond strength that is critical to maintaining the preferential oxidation of CO rather than H2 at high temperatures.