Reduction of NO by CO catalyzed by Fe-oxide/Al2O3: Strong catalyst-support interaction for enhanced catalytic activity

Abstract

Fe-oxide/Al2O3 catalysts were fabricated by depositing Fe-oxide nanoparticles with a lateral size less than ~2 nm in a highly dispersed manner within mesoporous Al2O3 using temperature-regulated chemical vapor deposition (TRCVD). The Fe-oxide/Al2O3 catalysts were post-annealed at either 450 °C (for 2 h) or 750 °C (for 2 or 8 h) and were used to catalyze NO reduction by CO. Catalytic activity was significantly enhanced with increased annealing temperature and time. Secondary ion mass spectrometry using Bi3+ as the primary ion shows an increase in the FeAlO+ signal from the interfaces between Fe-oxide and Al2O3 with increasing annealing temperature and time, suggesting that the enhanced interaction between Al2O3 and Fe-oxide is responsible for the increased catalytic activity. It is shown that TRCVD with a proper post-annealing step is a competitive tool for preparation of heterogeneous catalysts with highly dispersed catalyst nanostructures within mesoporous substrates that contain rich oxide/oxide interfaces and allow enhanced catalytic activity.