Barrett Dean H, Scurrell Michael S, Rodella Cristiane B, Diaz Beatriz, Billing David G, Franklyn Paul J
Molecular Sciences Institute , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa . Email:
Brazilian Synchrotron Light Laboratory (LNLS)/Brazilian Center for Research in Energy and Materials (CNPEM) , C. P. 6192 , 13083-970 , Campinas , SP , Brazil . Email:
Chem Sci. 2016 Nov 18;7(11):6815-6823. doi: 10.1039/c6sc01597b. Epub 2016 Jul 20.
When Au is subdivided to the nanoscale its reactivity changes from an inert nature to one of incredible reactivity which is not replicated by other catalysts. When dispersed onto metal oxides such as TiO, nano-Au has shown high reactivities for a multitude of reduction and oxidation reactions of industrial importance with potential and current uses such as, CO oxidation, NO reduction, purification of hydrogen for fuel cells, water gas shift reactions, abatement of volatile organic compounds (VOC's) as well as pollution and emission control systems such as autocatalysts. However, many industrially important reactions and applications operate under harsh conditions where the catalyst is exposed to high temperatures and further needs to operate for extended periods of time. These conditions cause Au nanoparticle sintering whereby small, highly active clusters form large clusters which are catalytically inactive. For this reason, research into stabilizing Au nanoparticles has abounded with a goal of producing durable, thermally stable catalysts for industrial applications. Here we show a durable, thermally stable Au-TiO catalyst which has been developed by rational design. The catalyst exhibits a 3-dimensional, radially aligned nanorod structure, already locked into the thermodynamically stable polymorph, a scalable and facile synthesis, with Au nanoparticles isolated on the support structure. As the Au nanoparticles are highly stable the new catalyst is able to maintain light-off for CO oxidation below 115 °C even after multiple cycles at 800 °C. This ability of the catalyst to resist multiple thermal cycles to high temperature while remaining active at low temperatures shows promise for various industrial applications. The thermal stability of the catalyst is investigated and characterized through morphological and structural studies.
当金被细分到纳米尺度时，其反应性从惰性转变为具有令人难以置信的反应性，这是其他催化剂所无法复制的。当分散在诸如二氧化钛等金属氧化物上时，纳米金已显示出对许多具有工业重要性的还原和氧化反应具有高反应性，其潜在和当前用途包括一氧化碳氧化、氮氧化物还原、燃料电池氢气净化、水煤气变换反应、挥发性有机化合物（VOC）减排以及诸如自动催化转化器等污染和排放控制系统。然而，许多具有工业重要性的反应和应用是在苛刻条件下进行的，催化剂会暴露在高温下，并且需要长时间运行。这些条件会导致金纳米颗粒烧结，即小的、高活性的团簇形成大的团簇，而这些大团簇没有催化活性。因此，关于稳定金纳米颗粒的研究大量涌现，目标是生产出用于工业应用的耐用、热稳定催化剂。在此，我们展示了一种通过合理设计开发的耐用、热稳定的金 - 二氧化钛催化剂。该催化剂呈现出三维径向排列的纳米棒结构，已锁定在热力学稳定的多晶型物中，合成方法可扩展且简便，金纳米颗粒孤立在载体结构上。由于金纳米颗粒高度稳定，即使在800℃经过多次循环后，这种新型催化剂仍能在115℃以下保持一氧化碳氧化的起燃温度。这种催化剂能够抵抗多次高温热循环同时在低温下保持活性的能力，在各种工业应用中显示出前景。通过形态学和结构研究对催化剂的热稳定性进行了研究和表征。
