BaCeO3 钙钛矿型氧化物的储氮和抗硫性能研究

采用改进的溶胶-凝胶法制备了钙钛矿结构的BaCeO3样品,在此基础上再用浸渍法制备了Pt/BaCeO3、 Rh/BaCeO3、 Pt-Rh/BaCeO3样品,并用机械混合γ-Al2O3,再浸渍贵金属的方法制备了Pt/BaCeO3/γ-Al2O3、 Rh/BaCeO3/γ-Al2O3、 Pt-Rh/BaCeO3/γ-Al2O3样品.储氮量(NSC)结果表明:对未加γ-Al2O3的BaCeO3来说,贵金属的加入反而使NSC减小.加入贵金属催化剂的储氮量(NSC)大小为: Pt的最大, Rh的次之, Pt-Rh的最小.γ-Al2O3的加入对BaCeO3吸收NO和O2没有影响.而对于BaCeO3/γ-Al2O3样品,贵金属的加入使NSC值提高了3倍以上.讨论了贵金属加入到BaCeO3/γ-Al2O3样品中显著提高样品储氮能力的原因.结合XRD结果表明,钙钛矿 BaCeO3相是Ba-Ce-O样品主要的NOx储存活性中心.NSC结果还表明, BaCeO3和Pt/BaCeO3催化剂在SO2为≤0.006%时具有较好的抗硫性能.而Pt/BaCeO3/γ-Al2O3催化剂不但具有较好的储氮能力而且具有更好的抗硫性能.

The NOx Storage and Resistance of SO2 Poison on the BaCeO3 Perovskite Type Oxides

The BaCeO3perovskite type samples are prepared by the improved sol-gel method. Besides, the Pt/BaCeO3, Rh/BaCeO3, Pt-Rh/BaCeO3and the Pt/BaCeO3/γ-Al2O3, Rh/BaCeO3/γ-Al2O3, Pt-Rh/BaCeO3/γ-Al2O3are also prepared. The results showthat adding precious metals, the NSC of the BaCeO3samples decrease. The sequence ofNSC is the Pt>Rh>Pt-Rh. Adding onlyγ-Al2O3has no effect on the NSC of the BaCeO3sample. However, the NSC of Pt/BaCeO3/γ-Al2O3sample increases more than three times as much as that of the BaCeO3/γ-Al2O3. The reason of the Nox storage enhancement by adding precious metals is discussed. Combining with XRD analysis, the perovskite type of BaCeO3is the main active phase ofNOxstorage forthe Ba-Ce-Osample. The results also indicate thatthe BaCeO3and Pt/BaCeO3samples keep the ability to resist poison produced by SO2at≤0. 006% SO2, and the Pt/BaCeO3/γ-Al2O3 sample possesses not only high capacity of NOxstorage but also high ability to resist poison produced by SO2.