稀土改性Pd/Al_2O_3催化剂的性能:甲醇分解的活性和选择性

Modification of Catalytic Properties of Pd/Al_2O_3 by Rare Earth Addition: Catalytic Activity and Selectivity in Methanol Decomposition

用稀土金属氧化物CeO2 和La2 O3改性γ Al2 O3担载Pd制备了一系列甲醇分解催化剂 ,并考察了Pd盐前驱体 (氯盐或硝酸盐 )、稀土种类 (镧或 /和铈 )、稀土金属氧化物含量 ( 0 %～ 30 % )、浸渍方法 (顺序浸渍或共浸渍 )等对催化剂性能的影响。结果表明 :CeO2 能提高Pd/Al2 O3催化剂的甲醇分解活性 ,La2 O3能提高催化剂的CO和H2 选择性 ,而CeO2 和La2 O3在γ Al2 O3上对Pd的催化性能表现出一种协同作用。在10 %的La2 O3和 2 2 %的CeO2 共同改性的催化剂上 ,2 5 0℃、甲醇液体空速 1 8h- 1 条件下反应甲醇转化率达到 91 4% ,CO(H2 )的选择性几乎为 10 0 %。

A series of Pd catalyst supported by CeO 2 and La 2O 3 modified γ Al 2O 3 was prepared for methanol decomposition. The catalytic properties were investigated and the effect of the following parameters was addressed: (1) Precursor salt of Pd (chloride or nitrate). (2) Rare earth nature (La and/or Ce). (3) Rare earth content (0～30%). (4) Impregnation mode (successive impregnations or co impregnation). A synergistic effect between CeO 2 and La 2O 3 on γ Al 2O 3 is observed for promoting the catalytic properties of Pd, which results in high activity and selectivity for methanol decomposition into CO and H 2. For a methanol LHSV of 1 8 h -1 , at 250 ℃ methanol conversion reaches 91 4% with almost 100% selectivity of H 2 and CO.