Mosallanejad Sara, Dlugogorski Bogdan Z, Kennedy Eric M, Stockenhuber Michael
School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
School of Engineering and Information Technology, Murdoch University, Murdoch, Western Australia 6150, Australia.
ACS Omega. 2018 May 18;3(5):5362-5374. doi: 10.1021/acsomega.8b00201. eCollection 2018 May 31.
Catalysts of iron oxide on γ-alumina and silica which were prepared by an incipient wetness impregnation technique have been investigated in an effort to understand how the surface chemical properties are influenced by the nature of the supports. Surprisingly, this is the first study to compare in depth the influence of the supports on physicochemical parameters such as acidity, site nuclearity, and reducibility. In this study, surface characterisation techniques including N physisorption at -196 °C, ammonia temperature-programmed desorption, inductively coupled plasma optical emission spectrometry, temperature-programmed reduction with hydrogen, CO-chemisorption, scanning electron microscopy, transmission electron microscopy, and NO adsorption by in situ Fourier transform infrared spectroscopy have been performed to understand the different surface reactions occurring over the two different supports. The aim of this study is to ascertain the primary differences between these two catalysts using several catalyst characterization techniques and correlate their chemical and structural differences to their catalytic activity in the conversion of 2-chlorophenol. The results disclose a higher density of acid sites, a smaller particle size of iron oxide, stabilization of Fe(II) aluminate after reduction on the alumina surface, and finally, the formation of isolated iron cations on the surface of alumina which are notably absent on the silica-supported catalyst.
通过初湿浸渍技术制备的负载于γ-氧化铝和二氧化硅上的氧化铁催化剂已得到研究，旨在了解载体性质如何影响其表面化学性质。令人惊讶的是，这是第一项深入比较载体对酸度、位点核性和还原性等物理化学参数影响的研究。在本研究中，采用了多种表面表征技术，包括在-196°C下的N物理吸附、氨程序升温脱附、电感耦合等离子体发射光谱法、氢气程序升温还原、CO化学吸附、扫描电子显微镜、透射电子显微镜以及原位傅里叶变换红外光谱法进行NO吸附，以了解在两种不同载体上发生的不同表面反应。本研究的目的是使用多种催化剂表征技术确定这两种催化剂之间的主要差异，并将它们的化学和结构差异与其在2-氯苯酚转化中的催化活性相关联。结果表明，氧化铝表面的酸位点密度更高、氧化铁颗粒尺寸更小、还原后铝酸亚铁更稳定，最后，在氧化铝表面形成了孤立的铁阳离子，而在二氧化硅负载的催化剂上则明显不存在。
