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

1067020 klie我们这个时代最大的社会挑战之一是寻求替代燃料资源，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，传统的发酵制醇途径往往是缓慢和低效的，而化学制醇途径主要是酸催化过程，产生大量的浪费。来自芝加哥伊利诺伊大学的首席研究员罗伯特·f·克利和兰德尔·迈耶认为，如果能使其成为一个有效的催化过程，另一种途径是最好的选择。在这一提议中，将研究使用非均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）产生的合成气转化为乙醇和其他醇的可行性。关键是利用铑在费托反应中产生氧的独特活性。PIs将专注于发展对如何在促进铑催化剂上有效合成乙醇的基本理解。不幸的是，大多数使用未促进的Rh催化剂的CO加氢研究表明，甲烷具有较强的选择性，而氧化选择性较低。有必要对醇的选择性进行重大改进。根据pi的说法，改进这一工艺的关键在于解开催化剂促进剂的秘密。pi相信，通过对负责高度选择性和主动将合成气转化为酒精的活性位点进行详细调查，可以取得实质性进展。如果可以明确地确定该位点，则可以开发合成方法来适当地针对其创建，从而产生所需的高活性和选择性催化剂。表征方法是关键。然而，从许多传统的光谱技术（无法确定位置）中可以提取的大量信息与从传统的显微镜技术（无法表征组成和键合）中可以获得的信息之间存在信息鸿沟。为了规避这些限制，pi将结合他们在两个不同领域的专业知识，化学工程和凝聚态物理，形成一个跨学科的研究团队。z对比成像、电子能量损失谱（EELS）和使用密度泛函理论（DFT）的第一性原理建模相结合，可以潜在地填补这一“信息空白”。这项工作的优势在于PIs能够合成促进铑纳米催化剂，在原子尺度上表征其原子和电子结构，并使用从头算密度泛函理论（DFT）计算将这些结构与选择性醇形成联系起来。为了实现这一目标，pi将把他们在化学工程和凝聚态物理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。这项研究旨在提供基本的材料科学知识，这将有助于理解和开发潜在的下一代纳米催化剂的新能力。该课程的一个重要特点是通过对实验和理论材料科学学生的培训，将研究和教育相结合。这对小组里的研究生很有价值。此外，学校和pi很好地融入了非常强大的少数民族和STEM项目，这是该项目更广泛教育影响的一个特征。

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.