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 catalyst were characterized by XRD, TG-DSC, SEM, XPS, CO2-TPD and soot-TPO techniques. All the samples showed T10, T50 and T90 at about 400 °C, 410 °C and 430 °C, respectively. The very low value for △T (T50−T10) of approximately 10°C implied a high reaction rate in the catalytic combustion process. K-Sep-400 showed good reusability with the T50 of about 470 °C after 5 cycles of TPO runs, as well as favourable hydrothermal stability. The co-existed potassium species (KNO3, K2O and K-O-Si) in the sepiolite paper catalysts could participate cooperatively and play decisive roles in soot catalytic oxidation process. The atomic ratio of free to confined K species was calculated from XPS (K2p) results, which was decreased with elevated sintering temperatures of sepiolite paper matrix.