La_(1-x)Sr_xCoO3 (x=0, 0.2) perovskites type catalyst for carbon monoxide emission control from auto-exhaust

摘要

Perovskite type catalysts La_(1-x)Sr_xCoO3 (x=0, 0.2) composition prepared by co precipitation method which were tested for carbon monoxide (CO) oxidation. The prepared perovskite samples were characterized by X-ray diffraction (XRD), BET surface area, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), temperature-programmed reduction by hydrogen (H2-TPR). XRD analysis showed that La_(1-x)Sr_xCoO3 (x=0, 0.2) are a single-phase perovskite type oxides. Traces of La_(0.6)Sr_(0.4)CoO3 in addition to perovskite phase were detected in the La_(0.8)Sr_(0.2)CoO3 catalyst. Specific surface area of perovskites were 2.60 m~2g~(-1) and 5.31 m~2g~(-1) for LaCoO3 and La_(0.8)Sr_(0.2)CoO3 respectively. The catalytic activity of the perovskite samples (for low-temperature CO oxidation) was measured using a stainless steel reactor with an inlet gas mixture containing 1% CO, 1% 02 and 98% N2. The perovskites catalysts showed good structural and chemical stability and high activity for the catalytic CO oxidation reaction. La_(0.8)Sr_(0.2)CoO3 exhibited higher activity for CO conversion than LaCoO3. 100% CO oxidation at 268 °C was achieved with this catalyst. Strontium substitution in LaCoO3 is responsible for enhanced CO oxidation activity due to easy reduction of transition metal and oxygen desorption properties.