Au/TiO2 catalysts prepared by photo-deposition method for selective CO oxidation in H2 stream
Au/TiO2 catalysts prepared by photo-deposition method for selective CO oxidation in H2 stream
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DOI：
10.1016/j.ijhydene.2009.08.087
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发表时间：
2009-11
影响因子：
7.2
通讯作者：
Yi-fen Yang;P. Sangeetha;Yu‐Wen Chen
中科院分区：
文献类型：
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作者：
Yi-fen Yang;P. Sangeetha;Yu‐Wen Chen
采用光沉积（PD）法制备了一系列Au/ tio2催化剂。考察了不同制备参数（pH值、紫外光功率和照射时间）对催化剂性能的影响。采用电感耦合等离子体质谱、x射线衍射、x射线光电子能谱、透射电镜和高分辨率透射电镜对催化剂进行了表征。在固定床微反应器中，以CO: O2: H2: He= 1:1:49: 49（体积比）为进料，空速为30,000ml/gh，对H2stream （PROX）中的CO进行了优先氧化。用少量的o2考察了o2与CO或H2反应的选择性。钯法制备的Au/ tio2催化剂中，金颗粒在几纳米内的粒径分布较窄，为~ 1.5nm。沉积在载体上的金纳米粒子的粒径取决于辐照时间、紫外光源和制备的pH值。Au的电子结构是粒度的函数。Au粒度越小，Au阳离子的浓度越高。在较弱的紫外光功率、适宜的照射时间和pH值条件下，载体上的金颗粒即使呈粉末状也能得到很细的金颗粒。PD法制备的样品不需要热处理来还原Au离子，紫外线照射可以还原Au离子。因此，更容易有较小的颗粒尺寸。钯法制备的Au/ tio2催化剂在PROX反应中具有很强的活性和选择性。在长时间测试中，催化剂在80℃下稳定60h以上。
A series of Au/TiO2catalysts were prepared by photo-deposition (PD) method. Various preparation parameters, such as pH value, power of UV light and irradiation time on the characteristics of the catalysts were investigated. The catalysts were characterized by inductively-coupled plasma-mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The preferential oxidation of CO in H2stream (PROX) on these catalysts was carried out in a fixed-bed micro reactor with a feed of CO: O2: H2: He=1: 1: 49: 49 (volume ratios) and a space velocity of 30,000ml/gh. Limited amount of O2was used to investigate the selectivity of O2reacting with CO or H2. Au/TiO2catalysts prepared by PD method showed narrow particle size distribution of gold particles within few nanometers and were found to be ∼1.5nm. The particle size of gold nanoparticles deposited on the support depends on irradiation time, UV light source and pH value of preparation. The electronic structure of Au was a function of particle size. The smaller the Au particle size was, the higher the concentration of Au cation was. Using weak power of UV light, appropriate irradiation time and suitable pH value, very fine gold particles on the support could be obtained even in the powder form. The samples prepared with PD method did not need heat treatment to reduce Au cation, UV irradiation could reduce it. Therefore it is easier to have smaller particle size. Au/TiO2catalysts prepared by PD method were very active and selective in PROX reaction. In long time test, the catalysts were stable at 80°C for more than 60h.