Fuel reforming over Ni-based catalysts coupled with selective catalytic reduction of NOx

La2O2CO3, CeO2, ZrO2, and Al2O3 supported Ni catalysts were prepared by an impregnation method and employed for reforming of n-dodecane to simultaneously produce low molecular weight hydrocarbons (HCs) and H2. These reforming products served as reductants and promoters for the selective catalytic reduction (SCR) of NOx over Ag/Al2O3. N2 adsorption-desorption, X-Ray powder diffraction, H2 temperature programmed reduction, and thermogravimetric analysis were performed for Ni-based catalysts. It was shown that an increase in the redox performance of Ni-based catalysts enhanced the H2 production from fuel reforming but decreased the amount of HCs available for further SCR reaction. The temperature window for NOx removal using the coupled system shifted to lower temperatures at the expense of the NOx conversion. An optimal ratio of H2/HCs was achieved using a Ni/ZrO2+Ag/Al2O3 dual catalyst system, which exhibited high activity for NOx conversion at typical diesel exhaust temperatures. Studies on the durability and performance of this Ni/ZrO2+Ag/Al2O3 coupled system were also performed, and the results showed that the lifetime of the reforming catalyst may limit the system and requires further improvement.

Small molecular weight hydrocarbons and H2 produced from on-board fuel reforming over Ni-based catalysts were used as reductants in the selective catalytic reduction of NOx over Ag/Al2O3 catalysts at typical diesel exhaust temperatures.Figure optionsDownload as PowerPoint slide