Activity of PdO/SiO2 catalysts for CH4 oxidation following thermal treatments
Activity of PdO/SiO2 catalysts for CH4 oxidation following thermal treatments
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DOI：
10.1016/j.apcatb.2014.12.037
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发表时间：
2015-06
影响因子：
22.1
通讯作者：
Rahman Gholami;Kevin J. Smith
中科院分区：
文献类型：
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作者：
Rahman Gholami;Kevin J. Smith
本文报道了PdO/SiO_2催化剂在空气和空气/水中（温度<973 K）热处理的效果。PdO烧结在热老化过程中，在空气（干老化）和空气/水（水热老化）的存在下，但在添加的水的存在下，抑制的PdO微晶的生长和重组，在连续老化和循环老化实验中观察到。水热老化催化剂（PdO粒径<$3 nm）的甲烷氧化活性明显低于空气中热老化催化剂（PdO粒径<$14 nm）。与水热老化后PdO尺寸的小增长相比，通过XPS测量的Pd/Si比的显著降低表明PdO闭塞，因此水热老化后活性的显著损失。的PdO闭塞和抑制的PdO颗粒烧结是由于SiO2 overlayers上的PdO是一个结果的羟基的支持，增强的存在下添加的水。
The effect of thermal treatment of PdO/SiO2catalysts in air versus air/water at temperatures <973 K, is reported. PdO sinters during thermal aging in the presence of air (dry aging) and air/water (hydrothermal aging), but the growth and restructuring of the PdO crystallites is suppressed in the presence of added water, as observed in both continuous aging and cyclic aging experiments. The hydrothermally aged catalysts (PdO size ∼3 nm) showed significantly lower CH4oxidation activity than the catalysts thermally aged in air (PdO size ∼14 nm). A significant decrease in the Pd/Si ratio as measured by XPS, compared to a small growth in PdO size after hydrothermal aging, suggests PdO occlusion and hence a significant loss in activity following hydrothermal aging. The PdO occlusion and suppressed PdO particle sintering is attributed to SiO2overlayers on the PdO that are a consequence of hydroxyl mobility of the support, enhanced by the presence of added water.