The influence of alkali metal cations in substituted nanostructured LaCoO3 on oxidation catalytic activity

Thi Hoang Yen Quach, Thi Minh Nguyet Tran, Que Chi Tran, Quoc Trung Nguyen, Thi Toan Nguyen and Dang Khuong Le

Abstract

Perovskite-type oxides La_0.9M_0.1CoO₃ (M=K/Na/Li) were prepared by a citrate sol–gel method. These oxides were characterized by x-ray diffraction analysis (XRD), a scanning electron microscope (SEM) and the N₂ physisorption Brunauer–Emmitt–Teller (BET) method. Their catalytic activity was studied by a constant microflow method for CO- and C₃H₆-oxidation and by thermal decomposition of diesel soot. The results show that the obtained perovskite materials have a sphere shape, particles size of about 40–50 nm and surface area from 12.0 to 14.9 m² g⁻¹. They have high catalytic activities decreasing in the sequence K > Na > Li on conversion CO, C₃H₆ and diesel soot. The total conversion temperature of CO, C₃H₆ and diesel soot is 325 °C, 340 °C and 430 °C, respectively. Thus, these catalysts have high applicability in the removal of exhaust gas, especially from diesel engines