ZrO2和Al2O3载体对Mo基催化剂上甲烷化反应性能的影响

Effects of ZrO2 and Al2O3 on the performance of Mo-based catalysts in methanation

    摘要
  • 摘要: 通过共沉淀法制备了ZrO2和Al2O3载体，采用等体积浸渍法制备了MoO3质量分数为5%的Mo/ZrO2和Mo/Al2O3催化剂，并用于甲烷化反应。在三种反应气氛下对两种预硫化的Mo基催化剂进行评价，发现ZrO2载体均可显著促进甲烷化反应，同时能够促进水汽变换（WGS）反应。通过XRD、H2-TPR、XPS和TEM等表征发现，两种载体上Mo物种的硫化程度以及暴露的活性位数量不同，从而导致两种催化剂上催化性能差异显著。与Mo/Al2O3相比，Mo/ZrO2催化剂上的MoO3更易被还原，硫化程度也更高，并且Mo4+的含量更高，Mo6+的含量更低。虽然ZrO2载体上MoS2尺寸较大，边位置的Mo比例有所降低，但是由于MoS2沿ZrO2颗粒表面弯曲生长，使得MoS2基面成为反应的活性位；因此，Mo/ZrO2催化剂在甲烷化与WGS反应中表现出更优异的催化性能。

     

    Abstract: Mo/ZrO2 and Mo/Al2O3 catalysts with a MoO3 loading of 5% were prepared by incipient wetness impregnation method; the effect of support on the performance of Mo-based catalysts in methanation was then investigated in three different feeds. The results indicate that ZrO2 as a support can promote the methanation and water-gas shift (WGS) reaction. ZrO2 is beneficial to the sulfuration and reduction of MoO3. The Mo sulfidation degree and the content of Mo4+ on Mo/ZrO2 are higher than that on Mo/Al2O3. Besides, the curved MoS2 basal plane on Mo/ZrO2 can provide the active sites for methanation and WGS, which is effective to enhance the performance of Mo-based catalysts in methanation.

     

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