Potassium promoted macro-mesoporous Co3O4-La0.88Sr0.12CoO3−δ nanotubes with large surface area: A high-performance catalyst for soot removal

Abstract

The construction of porous perovskite nanotubular materials with a good intrinsic activity, as well as a greater dispersion of the active sites is an effective strategy to obtain a high-performance catalyst used in soot removal. Thence, macro-mesoporous Co3O4-La0.88Sr0.12CoO3−δ nanotubes with large specific surface area (154.4 m2·g−1) from the acid etching of the porous La0.6Sr0.4CoO3−δ nanotubes, are supported by 5% K through bubbling method following calcination for soot combustion. The relationship between the specific surface area and K dispersion and their effect on the activity are studied by a series of isothermal kinetic measurements combined with the characterizations and activity evaluation results. It can be found that the greater the amount is of K+ incorporated into perovskite lattice, the better the dispersion of K, as well as the La2O2CO3 formed on the catalyst surface, thus leading to the enhanced performance in the soot catalytic combustion. As a result, the 5% K supported macro-mesoporous Co3O4-La0.88Sr0.12CoO3−δ nanotubes after acid etching show good activity and stability, where the T50 is 338 °C (5% O2 + 500 ppm NO + 6% H2O) with a good CO2 selectivity (above 99%), the activate energy is 78.1 kJ·mol−1, and the turnover frequency is 5.14 × 10−4 s−1.