CeO_2和La_2O_3改性Pd/γ-Al_2O_3甲醇低温分解催化剂的研究 Ⅱ.La_2O_3对Pd/CeO_2/γ-Al_2O_3催化剂结构和性能的影响

Study of CeO_2- and La_2O_3-Modified Pd/γ-Al_2O_3 Catalyst for Methanol Decomposition at Low TemperatureⅡ. Effect of La_2O_3 on Structure and Properties of Pd/CeO_2/γ-Al_2O_3 Catalyst

在Pd/CeO2 /γ Al2 O3中进一步添加La2 O3,并考察了其催化甲醇分解性能 .结果表明 :La2 O3的加入抑制了副产物二甲醚的生成 ;随着La2 O3含量的增加 ,催化剂活性先降低后升高 ,w(La2 O3) =10 %时甲醇转化率达到极大值 (约 91 4 % ) .XRD ,BET ,NH3 TPD ,XPS ,H2 TPR和FT IR等表征结果表明 :La2 O3自身在γ Al2 O3载体上的分散性很好 ,并且促进了CeO2 在γ Al2 O3载体上的分散及其体相氧的还原 ,使Pd的分散度进一步提高 ,并使Pd和CeO2 之间的相互作用进一步增强 ,从而提高了催化剂催化甲醇分解的活性 .

The effect of La 2O 3 addition on structure and catalytic performance of Pd/CeO 2/γ-Al 2O 3 catalyst for methanol decomposition was investigated. The results showed that the activity of the catalyst was decreased when the La 2O 3 content was below 5%, while the selectivity for CO and H 2 was increased remarkably. Methanol conversion reached a maximum (ca 91 4%) when the La 2O 3 content increased to 10%, and then decreased with the continual increase of La 2O 3 content. The catalyst samples were characterized by XRD, BET, XPS, NH 3-TPD, H 2-TPR and FT-IR techniques. La 2O 3 could be dispersed well onγ-Al 2O 3, then promoted the dispersion and the reduction of CeO 2. Furthermore, the dispersion of Pd and the interaction between Pd and CeO 2 were also increased, which result in high catalytic activity for methanol decomposition.