A key to the storage stability of Au/TiO(2) catalyst.
A key to the storage stability of Au/TiO(2) catalyst.
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DOI：
10.1039/b807040g
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
Yu Wu;Keqiang Sun;Jie Yu;Bo-Qing Xu
中科院分区：
文献类型：
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作者：
Yu Wu;Keqiang Sun;Jie Yu;Bo-Qing Xu
通过改变沉积-沉淀法制备Au/TiO(2)样品的干燥温度和贮存时间，研究Au（3+）在Au/TiO(2)中所占比例对Au/TiO(2)室温下贮存稳定性的影响。在干燥器中精心设计的室温储存，在黑暗中排除任何光照射的干扰，参考了冰箱中的冷冻储存（255k）。样品通过精心校准的H(2)-TPR， TEM和TG测量进行了表征。Au（3+）离子的还原和金属Au颗粒的团聚是Au/TiO(2)在干燥储存过程中变质的主要原因。将H(2)-TPR法测定的Au（3+）离子百分比与Au/TiO(2)在273 K CO氧化过程中的储存稳定性进行对比，发现较高Au（3+）百分比（> ~ 90%）的Au/TiO(2)样品在干燥剂储存过程中比较高金属Au百分比的Au/TiO(2)样品更稳定。储存前新鲜Au/TiO(2)中的残余水对金在储存过程中的还原和团聚有促进作用。通过最大化Au（3+）离子的百分比和最小化新鲜样品中的残留水，Au/TiO(2)催化剂在干燥器中储存长达150天的黑暗中成功地避免了变质。讨论了Au/TiO(2)在干燥储存过程中变质的可能机理。
The effect of Au(3+) percentage in Au/TiO(2) on its storage stability at room temperature was studied by varying the drying temperature and storage duration of a deposition-precipitation prepared Au/TiO(2) sample. Carefully-designed room temperature storage in a desiccator, in the dark to exclude any interference of light irradiation, was referenced to the freezing storage (255 K) in a refrigerator. The samples were characterized by well-calibrated H(2)-TPR, TEM and TG measurements. Reduction of Au(3+) ions and agglomeration of metallic Au particles were shown to be the main reasons for the deterioration of Au/TiO(2) during desiccator-storage. Correlating the percentage of Au(3+) ions, determined by H(2)-TPR, with the storage stability of Au/TiO(2) for CO oxidation at 273 K revealed that Au/TiO(2) samples with higher Au(3+) percentages (>90%) were much more stable during the desiccator-storage than those with higher percentages of metallic Au. Residual water in fresh Au/TiO(2) before storage showed a promotional effect on gold reduction and agglomeration during storage. By maximizing the percentage of Au(3+) ions and minimizing the residual water in the fresh sample, the deterioration of the Au/TiO(2) catalyst was successfully avoided during desiccator-storage of up to 150 days in dark. A possible mechanism of Au/TiO(2) deterioration during the desiccator-storage was also discussed.