Facile surface improvement method for LaCoO3 for toluene oxidation

Abstract

The rational design of low-cost transition metal catalysts that exhibit high activity and selectivity may be the most significant area of investigation in heterogeneous catalysis. A selective dissolution method using acid solutions was previously reported to tune catalyst surfaces. In this work, LaCoO₃ (LCO-0) perovskite catalysts were synthesized by the traditional citrate sol–gel method for toluene oxidation. The catalytic activity of the LaCoO₃ treated with acetic acid (LCO-1) was significantly increased: the T₉₀ of LCO-1 was 223 °C, which was 40 °C lower than that of the untreated catalyst (LCO-0) under a weight hourly space velocity (WHSV) of 60 000 mL g⁻¹ h⁻¹. The exposed A-site cations of perovskite were slightly etched, but still preserved the original framework according to XRD, TEM, SEM and ICP results. Moreover, LCO-1 exhibited excellent stability even after 500 °C calcination. The high catalytic performance was mainly associated with improvements in reducibility, surface oxygen vacancies and surface area. The high stability was due to the preservation of the perovskite structure after acetic acid treatment.