Widening Temperature Window for CO Preferential Oxidation in H2 by Ir Nanoparticles Interaction with Framework Fe of Hexaaluminate

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 H-2 (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 similar to 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 degrees 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 H-2 at high temperatures.

Automated summary

It is crucial to develop an efficient noble-metal-based catalyst with wide temperature window and stability for CO preferential oxidation in H-2. A catalyst of Ir nanoparticles supported by Fe-substituted hexaaluminate has been synthesized, showing total CO conversion in an unprecedented temperature range and good resistance to CO2 and H2O. Detailed characterizations and DFT calculations reveal the interaction between Ir species and Fe cations in promoting low-temperature CO oxidation and maintaining CO preferential oxidation at high temperatures.