Preferential Oxidation of CO in H2-Rich Stream Over Au/CeO2-NiO Catalysts: Effect of the Preparation Method
Preferential Oxidation of CO in H2-Rich Stream Over Au/CeO2-NiO Catalysts: Effect of the Preparation Method
复制标题
Au/CeO2-NiO 催化剂上富 H-2 流中 CO 的优先氧化：制备方法的影响
DOI：
10.1007/s10562-017-2231-1
复制
发表时间：
2018-01-01
影响因子：
2.8
通讯作者：
Zhu, Huaqing
中科院分区：
文献类型：
--
作者：
Li, Shuna;Zhang, Yagang;Zhu, Huaqing
采用水热(HT)和共沉淀(CP)两种方法制备了CeO2-NiO复合氧化物，以其为载体，采用胶体沉积法制备了Au/CeO2-NiO催化剂，并将其用于富氢水蒸气中CO的优先氧化。采用N-2吸附、X射线衍射、透射电子显微镜、氢-2-TPR、拉曼光谱和XPS等表征手段，考察了制备方法对CeO2-NiO载体结构和Au/CeO2-NiO催化剂性能的影响。XPS和TEM结果表明，水热法制备的CeO2-NiO(HT)载体呈均匀的棒状，优先暴露CeO2的(110)和(100)晶面，而共沉淀法制备的CeO2-NiO(CP)载体由纳米棒和以CeO2的(111)面为主的不规则纳米颗粒组成。沉积金后，Au/CeO2-NiO(HT)和Au/CeO2-NiO(CP)催化剂沉积的Au纳米颗粒的状态和尺寸分布基本相同。H-2-TPR结果表明，在Au/CeO2-NiO催化剂中，Au的存在强烈促进了CeO2的还原。拉曼光谱表明，在CeO2中掺入Ni离子显著增加了CeO2-NiO载体中的氧空位数量，尤其是水热法制备的CeO2-NiO(HT)，这有利于金物种的分散和稳定。CeO2-NiO载体的结构和Au/CeO2-NiO在CO Prox中的催化活性与制备方法密切相关，Au/CeO2-NiO(HT)的催化活性远高于Au/CeO2-NiO(CP)。CeO2-NiO(HT)中较大比例的(110)和(100)CeO2晶面可以促进金物种的分散、氧空位的形成和氧物种的迁移，从而有效地提高了Au/CeO2-NiO(HT)催化剂在富氢蒸气中对CO Prox的氧化还原能力和活性。
Two methods, viz., the hydrothermal (HT) and co-precipitation (CP) methods, were used to prepare CeO2-NiO composite oxides; with them as the supports, Au/CeO2-NiO catalysts were prepared by the colloidal deposition method and used in the preferential oxidation (PROX) of CO in H-2-rich stream. Various characterization measures such as N-2 sorption, XRD, TEM, H-2-TPR, Raman spectroscopy and XPS were used to clarify the influence of preparation method on the structure of CeO2-NiO support and the performance of Au/CeO2-NiO catalyst. The XPS and TEM results reveal that the CeO2-NiO(HT) support prepared by hydrothermal method displays a uniform rod-like shape and exposes preferentially the (110) and (100) planes of CeO2, whereas the CeO2-NiO(CP) support prepared by co-precipitation method is composed of nanorods and irregular nanoparticles dominated by (111) facets of CeO2. After deposition of gold, both the Au/CeO2-NiO(HT) and Au/CeO2-NiO(CP) catalysts are alike in the state and size distribution of deposited Au nanoparticles. The H-2-TPR results indicate that the presence of Au strongly promotes the reduction of CeO2 in the Au/CeO2-NiO catalyst. Raman spectra illustrate that the incorporation of Ni ions into CeO2 remarkably increases the amount of oxygen vacancies in the CeO2-NiO supports, especially in CeO2-NiO(HT) prepared by hydrothermal method, which is beneficial to the dispersion and stabilization of gold species. The structure of CeO2-NiO support and catalytic activity of Au/CeO2-NiO in CO PROX is strongly related to the preparation method; Au/CeO2-NiO(HT) exhibits much higher activity than Au/CeO2-NiO(CP). The larger fraction of (110) and (100) CeO2 facets in CeO2-NiO(HT) can promote the dispersion of gold species, formation of oxygen vacancies and migration of oxygen species, which are effective to enhance the redox capacity and activity of the obtained Au/CeO2-NiO(HT) catalyst for CO PROX in H-2-rich stream.