Development and Performance Studies on Ion-Exchanged X-Zeolites as Catalysts for SI Engine Emission Control

Three catalysts based on X-zeolite have been developed by exchanging its Na⁺ ion with Copper, Nickel and Vanadium metal ions and tested in a stationary SI engine exhaust to observe their potentialities for NO_x and CO controlling. The catalyst Cu-X, in comparison to Ni-X and V-X, exhibits much better NO_x and CO reduction performance at any temperature. Maximum NO_x conversion efficiencies achieved with Cu-X, Ni-X and V-X are 62.2%, 59.7% and 56.1% respectively. Unlike noble metals, the doped X-zeolite catalysts, studied here, maintain their peak NO_x reduction performance through a wider range of A/F ratio. Back pressure developed across the catalyst bed is found to be well within the acceptable limits.