Preparation Of La_1-XCe_XMnO₃ Nano-powder And The Catalytic Activity For CNG Vehicle Exhaust Removal

Nowadays, with the great increasing of vehicle holding and the increasingly intensifying of the word wide oil crisis, more and more automotive consumers and producers pay their concerns on the reducing of the vehicle fuel consumption and exhaust emission. Natural gas as a clean energy fuels was used as a substitution to diesel, gasoline and other traditional fuels to solve the problem. However, the difficulty in oxidization of CH₄ in the emission limited the widely application of NG. In this paper, the rare earth perovskite-type La_1-XCe_XMnO₃ nano-power and the catalytic converter for CNG vehicle emission catalytic removal were successfully developed and the catalytic combustion of methane over the supported La-Mn perovskite catalysts was studied.1. A series of La_1-XCe_XMnO₃ (x = 0, 0.2, 0.4, 0.6, 0.8) perovskite catalysts were successfully prepared via a Sel-Gol method. By XRD, SEM and TEM the structure and morphology of the catalysts were characterized. The effect of calcination temperature and the amount of Ce-La substitution x on the microstructure of the perovskite was studied.2. The results showed that the perovskite structure could be formed only if the calcination temperature is above 700?C. The perovskite phase was dominant in the prepared sample, and the perovskite structure significantly grew in crystallinity when calcined at 800?C. The microstructure of the samples had surprisingly influence with the cerium substitution. When x = 0.2 the microstructure belonged to tetragonal system, while x > 0.2 which was transformed to trigonal system.3. The catalytic converter was successfully prepared by La_1-XCe_XMnO₃ nano-power dispersed inγ-Al₂O₃ slurry and supported on cordierite honeycomb ceramics. The effect of different amount of cerium on the catalytic removal of CH₄ CO and NOX in CNG vehicle emission was studied on a fixed bed reactor.4. The results showed that CH₄ initiation conversion temperature was increasing with the increasing of substitution, while the conversion rate at low temperature decreased. However, the final conversion rate was invariant. CO initiation and the semi-conversion temperature decreased with the substituted amount increasing, while final conversion temperature reached the lowest level on La0.6Ce0.4MnO3 catalysts. The catalysts showed poor ability on the removal of NOX.