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 Ⅰ.CeO_2改性Pd/γ-Al_2O_3催化剂的结构和性能

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

用XRD ,BET ,NH3 TPD ,TPR及XPS等手段对CeO2 改性Pd/γ Al2 O3 催化剂的结构和性能进行了表征 ,并考察了催化剂上甲醇低温分解的性能 .结果表明 ,CeO2 在γ Al2 O3 载体上容易聚集 ,不能完全掩蔽其表面酸性 ,并较大程度地降低了载体的比表面积 ;CeO2 的加入促进了Pd在载体上的分散 ,并且产生一种协同还原作用 .Pd的高度分散及其与CeO2 在γ Al2 O3

The CeO 2 modified Pd/ γ Al 2O 3 catalyst samples were tested for catalytic methanol decomposition at low temperature. The structure and properties of the catalyst samples were investigated by XRD, BET, NH 3 TPD, H 2 TPR and XPS techniques. The results showed that the CeO 2 was aggregated on γ Al 2O 3 and could not cover all the surface acidic sites. The BET area of the samples was decreased by the addition of CeO 2, while the dispersion of Pd was increased. A synergetic reduction of CeO 2 and Pd was also observed, thus the high dispersion of Pd and the interaction between CeO 2 and Pd seemed to play important roles in the reactivity of methanol decomposition. Under the condition of θ =250 ℃ and MHSV=1 8 h -1 , the methanol conversion reached 95 2% with 9 8% of selectivity for DME as the main by product over 22%CeO 2 modified Pd/Al 2O 3 catalyst (PAC22).