Microfibrous-structured silver catalyst for low-temperature gas-phase selective oxidation of benzyl alcohol
Microfibrous-structured silver catalyst for low-temperature gas-phase selective oxidation of benzyl alcohol
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DOI：
10.1016/j.apcatb.2010.06.023
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发表时间：
2010-08
影响因子：
22.1
通讯作者：
Miaomiao Deng;Guofeng Zhao;Qingsong Xue;Li Chen;Yong Lu
中科院分区：
文献类型：
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作者：
Miaomiao Deng;Guofeng Zhao;Qingsong Xue;Li Chen;Yong Lu
制备了一种高活性、高选择性的镍纤维负载银催化剂，用于苯甲醇的选择氧化反应。采用浸渍法将Ag（10wt%）负载到由5vol%的8 μm镍纤维组成的纸状微纤维结构上，制得Ag/Ni催化剂。通过简单的水预润湿和过夜干燥处理工艺，大大改善了镍纤维支撑体的润湿性。这产生了催化剂（Ag/Ni-纤维-M），其具有比使用未处理的载体的催化剂（Ag/Ni-纤维）更多的Ag阳离子和选择性活性氧物种。Ag/Ni-纤维-M比Ag/Ni-纤维表现出更高的低温活性/选择性，这可以归因于它们的银形态和颗粒尺寸的差异。观察到的最佳转化率和苯甲醛选择性对于Ag/Ni-纤维-M在300°C下均为97%，并且对于Ag/Ni-纤维在380°C下分别为91%和84%。苯甲醇的选择性氧化可通过直接O2活化途径和NiO参与的氧溢出途径同时进行。NixC相的形成发生，阻碍了后者的反应路线，从而导致部分失活。然而，废催化剂可以通过在400°C下的氧化处理恢复活性。
A highly active and selective silver on nickel fiber catalyst was successfully prepared for selective oxidation of benzyl alcohol. The Ag/Ni catalyst was obtained by loading Ag (10wt%) on paper-like microfibrous structure (consisting of 5vol% of 8-μm Ni-fiber) by impregnation method. The wettability of Ni-fiber support was vastly improved by a simple water pre-wetting and overnight drying treatment process. This yielded a catalyst (Ag/Ni-fiber-M) with more Ag cations and selectively active oxygen species than the catalyst (Ag/Ni-fiber) using the untreated support. The Ag/Ni-fiber-M showed much higher low-temperature activity/selectivity than the Ag/Ni-fiber, which could be attributed to the differences in their silver morphology and particle size. The best conversion and benzaldehyde selectivity observed were both 97% for Ag/Ni-fiber-M at 300°C, and 91 and 84% for Ag/Ni-fiber at 380°C, respectively. Benzyl alcohol selective oxidation would proceed concurrently through both direct O2activation route and NiOx-participating oxygen spillover route. Formation of NixC phase occurred and hampered the latter reaction route thereby leading to partial deactivation. However, spent catalyst could restore activity through an oxidation treatment at 400°C.