Effect of Water Vapor on the Accelerated Deterioration Treatment of Cu-SSZ-13 as Catalysts for Selective Catalytic Reduction

The effect of water vapor on the deterioration of Cu-SSZ-13 catalysts during hydrothermal treatment was investigated as a part of a study on the accelerated deterioration conditions for the selective catalytic reduction (SCR) catalyst in diesel vehicles. The standard SCR activity of samples hydrothermally treated in water vapor of concentrations ranging from 10 to 75% was investigated. The results showed that the higher the water vapor concentration, the higher the decrease rate of the catalytic activity. The properties of the samples were studied in detail through a series of characterizations. The hydrothermal deterioration occurred in two stages: the first involved a decrease in the acid amount with a certain degree of structure retention, while the second involved a decrease in the number of active sites due to Cu aggregation and the collapse of the structure. This phenomenon was accelerated by the increased water vapor concentration during the hydrothermal treatment.