Quick drying process: a promising strategy for preparing an egg-shell-type Cu/γ-Al2O3 catalyst for direct N2O decomposition

Abstract

The egg-shell-type γ-Al₂O₃ catalyst having a Cu shell was developed using the simple quick drying (QD) technique. The fabricated catalyst is developed for use in a direct N₂O decomposition (deN₂O) technology. To observe the effective manufacturability of egg-shell-type catalysts, we compared three different drying methods: oven drying (OD), vacuum oven drying (VOD), and quick drying (QD). The SEM/EDS analysis, deN₂O test, and kinetic properties (activation energy, reaction rate and turnover frequency) confirmed that the QD method is suitable for the effective manufacturability of the egg-shell-type catalyst. The simple QD method induces the formation of a thin and uniform Cu shell on the surface of the pellet support, which promotes N₂O decomposition. A series of QD-Cu(x)/γ-Al₂O₃ (x = 5, 10, and 15 wt%) catalysts were prepared by the QD method. The QD-Cu(10)/γ-Al₂O₃ catalyst with an appropriate amount of Cu exhibited an outstanding N₂O decomposition conversion rate and abundant Cu¹⁺ active sites with high reducibility. A long-term stability test with 1% and 20% N₂O was carried out for 360 h and 500 h, respectively. During the long-term stability tests under changing feed conditions, such as temperature, air, and steam, the catalytic activity and copper distribution remained very stable, indicating that the QD-Cu(10)/γ-Al₂O₃ catalyst has high durability and reliability.