用浸渍法制备了Pd/γ-Al_2O_3和Pd/Ce_(0.65)Zr_(0.35)O_22种甲醇分解催化剂.采用XRD,NH_3-TPD(NH_3-Temperature-Programmed Desorption),XPS及H_2-TPR(H_2-Temperature.Programmed-Redution)等手段对2种催化剂的结构和性能进行表征,并考察了催化剂上甲醇低温分解的活性.结果表明,Pd/Ce_(0.65)Zr_(0.35)O_2催化剂具有较弱的表面酸性及良好的低温还原性能;XPS结果表明2种催化剂中的Pd均以氧化态形式存在,并且Pd在Ce_(0.65)Zr_(0.35)O_2固溶体上呈高度分散状态,Pd与Ce间具有较强的相互作用.结合活性考察可知,pd~+的存在有利于甲醇的分解.Pd/Ce_(0.65)Zr_(0.35)O_2催化剂具有高的催化活性,220℃时甲醇转化率接近100%.
Two kinds of palladium methanol decomposition catalysts were prepared by immersion method with γ-Al_2O_3 and Ce_(0.65)Zr_(0.35)O_2 as supports, respectively. XRD, XPS, H_2-TPR (H_2-Temperature-Programmed-Redution) and NH_3-TPD (NH_3-Temperature-Programmed Desorption) techniques were used to study the microstructure and performance of catalyst samples and the activity of methanol low-temperature decomposition for the catalysts was also investigated. Testing results show that the Pd/Ce_(0.65)Zr_(0.35)O_2 catalyst possesses weak surface acidity and good low-temperature reducibility. XPS results confirm that palladium of the two catalysts exist as oxidation state. Combining with catalytic activity, it can be known that Pd~+ is advantageous in the methanol decomposition. High dispersion of palladium in ceria-zirconia solid solution and strong interaction between Pd and supports can decrease activation energy which results in high catalytic activity for methanol decomposition. The conversion of methanol nearly achieved 100% at 220 ℃ for Pd/Ce_(0.65)Zr_(0.35)O_2.
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