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

Abstract

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 T₁₀, T₅₀ and T₉₀ at about 400 °C, 410 °C and 430 °C, respectively. A very low ΔT (T₅₀ − T₁₀) value of approximately 10 °C implied a high reaction rate in the catalytic combustion process. K–Sep-400 showed good reusability with a T₅₀ value of about 470 °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.