Highly flexible and active potassium-supported sepiolite paper catalysts for soot oxidation

Highly flexible and active potassium-supported sepiolite paper catalysts were fabricated via a facile wet paper-making method. The structure, physicochemical properties and catalytic performance of the paper catalysts were characterized by XRD, TG-DSC, SEM, XPS, CO2-TPD and soot-TPO techniques. All the samples showed T-10, T-50 and T-90 at about 400 degrees C, 410 degrees C and 430 degrees C, respectively. A very low Delta T (T-50 - T-10) value of approximately 10 degrees C implied a high reaction rate in the catalytic combustion process. K-Sep-400 showed good reusability with a T-50 value of about 470 degrees C after 5 cycles of TPO runs, as well as favourable hydrothermal stability. The co-existing potassium species (KNO3, K2O and K-O-Si) in the sepiolite paper catalysts could participate cooperatively and play decisive roles in catalytic soot oxidation processes. The atomic ratio of free to confined K species was calculated from XPS (K2p) results, which decreased with elevated sintering temperatures of the sepiolite paper matrix.