Insights into the catalytic performance of LDHs-derived CoAlO oxides with different anions intercalation for propane total oxidation

Abstract

Constructing effective and stable non-noble metal catalysts is of great significance and prospect for catalytic oxidation of stable light alkanes at low temperature. Herein, the CoAlO oxide catalysts derived from the CoAl layered double hydroxides (LDHs) intercalated with CO32–, CH3COO– (Ac), SO42-, NO3– and citrate (CA) anions were prepared, and their catalytic performances for propane oxidation were investigated. Among all CoAlO catalysts, the CoAlO-Ac-3 catalyst (CH3COO– anion intercalation) exhibited better catalytic activity for propane oxidation (T90 = 300 °C), with the highest reaction rate (2.79 × 10-7 mol g−1 s−1) and TOF value (0.13 × 10-3 s−1) at 240 °C. Characterization results revealed that the interlayer anions affected the valence distribution of metals and surface active oxygen species, and CH3COO– anion intercalation CoAlO-Ac catalyst showed the highest Co3+/Co2+ molar ratio and active oxygen species. Combining with Raman and in-situ DRIFTS results, the lattice distortion of catalyst caused by the interlayer anions promoted the migration of active oxygen species, thus accelerating the propane adsorption and activation. Meanwhile, CoAlO-Ac-3 catalyst exhibited excellent stability and water resistance for propane oxidation.