Effect of Support Particle Size in Steam Reforming of Ethanol over Co/CeO2 Catalysts
Effect of Support Particle Size in Steam Reforming of Ethanol over Co/CeO2 Catalysts
复制标题
DOI：
10.1021/cs3004159
复制
发表时间：
2012-11-01
期刊：
影响因子：
12.9
通讯作者：
Ozkan, Umit S.
中科院分区：
文献类型：
--
作者：
Soykal, I. Ilgaz;Sohn, Hyuntae;Ozkan, Umit S.
研究了纳米级和微级两种不同粒径的氧化铈载体上的Co催化剂在乙醇和乙烯蒸汽重整中的性能。采用反应前和反应后的表征技术，包括高分辨率透射电子显微镜、程序升温氧化、分散、孔径测量、原位x射线衍射（XRD）和x射线吸收精细结构光谱（XAFS）研究来检验催化剂的还原性。稳态活性测试表明，纳米颗粒对乙醇有较高的重整活性，但也有较高的乙烯收率。尽管乙烯产率很高，但纳米颗粒负载的催化剂被证明具有很高的抗结焦性，而较大的二氧化铈颗粒负载的催化剂则容易结焦。乙烯重整实验表明，其活性和稳定性有显著差异。裸体支架也进行了活性测试，纳米颗粒支架具有较高的脱水活性。在ESR期间进行的Operando DRIFTS实验显示了表面物种的差异。使用甲醇氧化作为探针反应的脉冲实验表明，氧化还原位点和碱性位点的相对丰度存在差异。裸铈载体对乙醇脱水也表现出显著的活性，但对碳-碳裂解没有明显的活性。纳米颗粒支撑催化剂的优异性能被认为是由于多种因素的综合作用，包括还原性增强、金属分散性改善以及表面氧化还原位点相对丰度的差异。所有这些性质，以及催化性能，似乎都受到载体粒径的影响
Co catalysts supported on ceria supports with two different particle sizes, one in the micro- and the other in the nano range, were investigated for their ethanol and ethylene steam reforming performance. Pre- and post reaction characterization techniques, including high resolution transmission electron microscopy, temperature programmed oxidation, dispersion, pore size measurements, in situ X-ray diffraction (XRD) and X-ray absorption fine structure spectroscopy (XAFS) studies were performed to examine the reducibility of the catalysts. Steady-state-activity testing has shown nanoparticles to have a higher reforming activity for ethanol, but also high ethylene yields. In spite of the high ethylene yields, catalysts supported on nanoparticles proved to be highly resistant to coking while the catalysts supported on larger ceria particles suffered from coke formation. Reforming experiments performed with ethylene showed significant differences in activity and stability. Bare supports were also tested for activity and the nanoparticle support was seen to have high dehydration activity. Operando DRIFTS experiments performed during ESR showed differences in surface species. Pulse experiments performed to use methanol oxidation as a probe reaction suggested differences in the relative abundance of redox sites and basic sites. The bare ceria supports also exhibited significant activity for ethanol dehydration, but not for C C cleavage. The superior performance of the catalysts supported on nanoparticles is thought to be due to a combination of factors, including increased reducibility, improved metal dispersion, and a difference in relative abundance of redox sites on the surface. All of these properties and, in turn, the catalytic performance, appear to be affected by the particle size of the support