Micromorphological control of porous LaMnO3 and LaMn0.8Fe0.2O3 and its catalytic oxidation performance for CO

A molten salt method was adopted to prepare porous LaMnO3 and LaMn(0.8)Fe(0.2)o(3) with different morphologies, using hierarchical porous MnO2 microspheres (S80, S90, S80-1) as precursors in eutectic NaNO3-KNO3, separately. The results show that perovskite phase LaMn0.8Fe0.2O3 can be formed at 435.5 degrees C. Spherical porous LaMn0.8Fe0.2O3 can be synthesized at 450 degrees C for 4 h, which was composed of aggregated nanocrystallites. With morphologies similar to S90 and S80-1, LaMnO3 can also be prepared at 450 degrees C and 500 degrees C for 4, respectively. Additionally, the sample LaMn0.8Fe0.2O3 also displayed a higher BET surface area of 55.73 m(2)/g with an average pore size of about 9.38 nm. The results of CO conversion on each sample showed that LaMn0.8Fe0.2O3 owned the best catalytic activity (T-50 = 187 degrees C and T-90 = 200 degrees C) and it was available to improve the catalytic activity through reducing the molar ratio of La(NO3)(3)center dot 6H(2)O and S80-1 to lower the amount of La(OH)(2)NO3.