Effect of Tungsten Oxide Addition on the Catalytic Activity of γ-Al_2O_3 for NO_x Reduction from Fuel-Lean Gas Mixtures

摘要

Non-zeolitic catalysts are increasingly being considered as durable alternatives in automotive lean-NO_x catalysis. This study focused on increasing the acidity of γ-Al_2O_3 through the addition of tungsta (WO_3) and increasing the resulting catalytic activity using simulated lean-burn engine exhaust. The effects of WO_3 loading, space velocity, catalyst temperature, hydrocarbon and sulfur dioxide concentrations, and hydrothermal aging on the NO_x reduction activity of WO_3/ Al_2O_3 composite oxides were studied. It was found that tungsta-modified alumina compositions had higher NO_x removal activity under lean-burn conditions than the unmodified γ-Al_2O_3. Maximum NO_x conversion occurred at a 1 wt % loading of WO_3 on γ-Al_2O_3 at a temperature of 580℃.