Understanding the Active Sites in Selective Alcohol Synthesis with Promoted Rh Catalysts

我们这个时代最大的社会挑战之一是寻找替代燃料资源，以减少我们目前的温室气体排放和对外国原油的依赖。特别令人感兴趣的是从纤维素生物质中生产乙醇作为化石燃料的添加剂/替代品。然而，传统的酒精发酵路线往往缓慢而低效，而酒精的化学路线主要是酸催化的过程，会产生大量的废物。伊利诺伊大学芝加哥分校的首席研究员罗伯特·F·克利和兰德尔·迈耶认为，如果能使其成为有效的催化过程，替代路线是最好的选择。在这个方案中，将研究利用多相纳米催化剂将气化木质素(丰富、廉价且几乎没有竞争应用)的合成气转化为乙醇和其他醇的可行性。关键是利用Rh在费托反应中产生含氧物的独特活性。PIS将集中发展对如何在改进的Rh催化剂上实现有效的乙醇合成的基本理解。不幸的是，大多数使用非助剂Rh催化剂的CO加氢研究表明，甲烷对甲烷有很强的选择性，而含氧物选择性很低。在酒精选择性方面有必要进行重大改进。根据PIS的说法，改进这一工艺的关键在于解开催化剂助剂的秘密。PIs相信，通过详细调查负责高选择性和活性地将合成气转化为酒精的活性部位，可以取得实质性进展。如果可以明确地确定该位置，则可以开发合成方法来适当地针对其生成，从而产生所需的高活性和选择性催化剂。表征方法是这一点的关键。然而，从许多传统光谱技术(无法确定位置)可以提取的大量信息与从传统显微技术(无法表征组成和成键)可以获得的信息之间存在信息鸿沟。为了绕过这些限制，私人投资机构将结合他们在化学工程和凝聚态物理这两个不同领域的专业知识，组成一个跨学科的研究团队。Z-对比度成像、电子能量损失谱(EELS)和基于密度泛函理论(DFT)的第一性原理建模相结合，有望填补这一“信息鸿沟”。这项工作的优势在于PI能够合成促进的Rh纳米催化剂，在原子尺度上表征它们的原子和电子结构，并用从头计算密度泛函理论(DFT)将这些结构与选择性醇的形成关联起来。为了实现这一目标，私人投资促进机构将把他们在化学工程和凝聚态物理这两个不同领域的专业知识结合起来，组成一个跨学科的研究团队。这项研究旨在贡献基础材料科学知识，帮助理解和开发潜在的下一代纳米催化剂的新能力。该计划的一个重要特点是通过培养学生在实验和理论材料科学方面的研究和教育相结合。这将对小组中的研究生有很大的价值。此外，学校和私人投资机构很好地融入了非常强大的少数民族和STEM方案，这是该项目更广泛的教育影响的一个特点。

1067020KlieOne of the largest societal challenges of our time is the quest for alternative fuel resources that will reduce our current greenhouse-gas emissions and dependence on foreign crude-oil. Of particular interest has been the production of ethanol from cellulosic biomass as a fossil fuel additive/replacement. However, traditional fermentation routes to alcohols are often slow and inefficient, while chemical routes to alcohols are dominated by acid catalyzed processes which generate significant waste. Principal Investigators Robert F. Klie and Randall Meyer from the University of Illinois at Chicago believe an alternative route is the best choice, if it can be made to be an efficient catalytic process. In this proposal, the viability of converting syngas derived from gasified lignin (which is abundant, cheap, and has few competing applications) to ethanol and other alcohols using heterogeneous nano-catalysts will be studied. The key is to harness the unique activity of rhodium for oxygenate production in the Fischer-Tropsch reaction. The PIs will concentrate on developing a fundamental understanding of how efficient synthesis of ethanol can be achieved on promoted rhodium catalysts. Unfortunately, the majority of CO hydrogenation studies using unpromoted Rh catalysts have demonstrated a strong selectivity for methane with a low oxygenate selectivity. A significant improvement with regard to alcohol selectivity is necessary. According to the PIs, the key for improvement of this process lies in unlocking the secrets of catalyst promoters. The PIs are convinced that substantial gains can be made through a detailed investigation of active sites responsible for highly selective and active conversion of syngas into alcohol. If the site can be unambiguously identified then synthesis methods can be developed to properly target its creation, resulting in the highly active and selective catalyst desired. Characterization methods are key to this. However there is an information gap between the extensive information that can be extracted from the many conventional spectroscopic techniques (without the ability to define the location), and what can be obtained from traditional microscopy techniques (without the ability to characterize composition and bonding). In order to circumvent these limitations, the PIs will combine their expertise in two dissimilar areas, chemical engineering and condensed matter physics to form an interdisciplinary research team. The combination of Z-contrast imaging, electron energy loss spectroscopy (EELS), and first-principles modeling using density-functional theory (DFT) can potentially fill this "information gap. The strengths of this effort lie in the PIs ability to synthesize promoted Rh nano-catalysts, characterize their atomic and electronic structures on the atomic scale and correlate these with the selective alcohol formation using ab initio density functional theory (DFT) calculations. To achieve this goal, the PIs will combine their expertise in two dissimilar areas, chemical engineering and condensed matter physics to form an interdisciplinary research team. This research aims at contributing basic materials science knowledge that will aid the understanding and development of new capabilities for potential next generation nano-catalysts. An important feature of this program is the integration of research and education through the training of students in both experimental and theoretical materials science. This will be of great value to the graduate students in the groups. In addition the school and the PIs are well-integrated into very strong minority and STEM programs which are a feature of the broader educational impacts of this project.