Effect of Cerium on the Structure and Properties of LaMn Catalyst and γ-A1_2O_3 Washcoat

摘要

The influence of rare earth Cerium (Ce) on the structure and properties of automotive emission catalyst LaMn and washcoat materials γ-AI_2O_3 was studied by means of XRD, SEM, BET, and catalytic conversion measurement. The results showed that the thermostability of washcoat was positively improved by adding Ce into γ-AI_20_3. The temperature of phase transformation from γ-AI_20_3 to α-AI_2O_3 could be modified from 800°C to 1150°C with 6% CeO_2 additive. At the same time, the washcoat γ-AI_2O_3 could still present high surface area. By adding Ce into auto-catalyst LaMn, the oxidation ability of active materials had a little decrease for hydrocarbon (HC) and carbon monoxide (CO). However, the reduction ability of catalyst LaMn for NO_x was greatly modified. In 10% O_2, the conversion rate of NO_x could exceed 40% on the catalyst LaMn /Au with Ce. Not the formation and separation of perovskite crystals was only restrained by introducing Ce into catalyst LaMn, but the crystal size also decreased, so as to make a better contribution of active catalyst component on the surface.