Doping effects of Ni-MgO on the structure and performance of carbon nanotube-supported Pt catalysts for preferential oxidation of CO in a H(2) stream
Tanaka, Ken-ichi（ Saitama Inst Technol, Adv Sci Res Lab）
- 化学化工－已发表论文 
The preferential oxidation of CO (CO-PROX) in a H(2)-rich stream is performed on a series of supported Pt catalysts doped with Ni-MgO. The characterizations of the catalysts by means of in situ X-ray diffraction, high resolution transmission electron microscopy, and scanning transmission electron microscopy-energy dispersive spectroscopy reveal that the nanocomposites of Pt-Ni alloys that intimately adjoined Ni-MgO solid solution are present on the surfaces of carbon nanotube (CNT). However. the Pt-Ni alloying is hardly detected when the same compositions are supported on other carriers like active carbon, graphite, TiO(2). SiO(2) and Al(2)O(3) followed by identical treatment. The CNT-supported Pt(0.3)Ni(1.0)Mg(2.4) (Pt(0.3)Ni(1.0)Mg(2.5)/CNT, the data at subscript stand for the Pt/Ni/Mg atomic ratio) catalyst with overall metal loading of 15 wt% affords 100% CO conversion and 50% O(2) selectivity in H(2) at temperatures ranging from 333 to 453 K. whereas the CNT-supported Pt catalyst and the other carriers-supported Pt(0.3)Ni(1.0)Mg(2.4) ones perform very low or insufficient activities under the same reaction conditions. Further, the Pt(0.3)Ni(1.0)Mg(2.4)/CNT catalyst with a mean Pt-Ni particle size about 7.3 nm shows negligible drop in CO-PROX performance at 373 K for longer than 40 h on the streams either with or without H(2)O vapor and CO(2). The deactivation of the catalyst is largely due to the accumulation of H(2)O/OH(-) species and carbonates, which can be removed by calcination and reduction to get the regeneration of the CO-PROX performance as a result. The high performance of the catalysts is ascribed to the interaction between Pt and Ni with the formation of Pt-Ni alloy which is strongly interacted with Ni-MgO solid solution. (C) 2011 Elsevier B.V. All rights reserved.
CitationAPPLIED CATALYSIS A-GENERAL，2011,402（1-2）：168-175