Bio-inspired catalysts for the activation of aliphatic C-H bonds: toward the development of novel green processes

用于活化脂肪族C-H键的仿生催化剂：致力于开发新型绿色工艺

• 批准号: RGPIN-2014-06336
• 负责人: Castonguay, Annie
• 金额: $ 2.33万
• 依托单位: Institut national de la recherche scientifique
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612170
• 关键词: Bio; inspired; catalysts; activation; aliphatic

Nature has long been a source of inspiration for both scientists and artists. Some of the most ingeniously designed products and gadgets familiar to millions of people worldwide owe their origin to seemingly simple forms and patterns found in plants and wildlife. Although we lately learned plenty of information about how nature proceeds to perform various efficient chemical transformations, biological systems are complicated and still far from being fully understood. An example of such complex systems is the mild way nature converts atmospheric nitrogen to ammonia. For 100 years, ammonia has been exclusively produced from nitrogen and hydrogen gas via the Haber-Bosch process, a technique that requires very harsh conditions (350-550 °C, 150-350 atm). In contrast, some enzymes found in nature known as nitrogenases are able to easily achieve this transformation at ambient temperature and pressure. As it is the case for the breakage of the strong nitrogen triple bond, the controlled activation and functionalization of strong C-H bonds in hydrocarbons also remains a challenge. The vast majority of precious raw materials like liquid and gaseous hydrocarbons are simply burnt as fuels for heating and transportation, and only a modest portion of these C-H bond containing molecules (alkanes and aromatics) are converted into chemical intermediates on a large-scale for use in the chemical industry. The transition metal-catalyzed dehydrogenation of alkanes, which produces olefins, the major feedstock of chemical industry, is a green approach to bond construction strategies. This reaction allows the substitution of highly reactive mutagenic halogenated starting reagents that are currently used by industry by simple C and H containing compounds, and prevents waste production. The dehydrogenation of alkanes also generates hydrogen gas, which is a coveted non polluting energy source. Importantly, due to the reversibility of the reaction, catalysts able to dehydrogenate alkanes can potentially find applications in the field of hydrogen storage. There is a need for greener catalysts to be developed. For example, one of the technologies currently used by industry and which accounts for over 90% of ethylene production in North America requires temperatures in excess of 800 °C and produces 1-3 tons of CO2/ton of ethylene. Transition metal complexes as homogeneous catalysts for the dehydrogenation of alkanes allow milder reaction conditions as well as selectivity, but are mostly based on precious metals such as Ir and Rh. Using nature as a source of inspiration, our group will study complexes based on inexpensive metals, which have traditionally been overlooked to achieve the dehydrogenation of alkyl chains, and that are responsible for the activity of many enzymes, such as iron (Fe) or tungsten (W). Research on alternatives to the use of noble metals is a novel approach in the field of C-H activation catalyst development. Avoiding precious metals will lead to cheaper catalysts with minimum environmental and toxicological impact, and which can accomodate a huge scale of usage (high abundance). In this program, we propose to investigate the reactivity of W and/or Fe mono- and multi-metallic species bearing rigid and highly tuneable ligands, leading to carefully engineered alkane dehydrogenation catalysts that can be efficient under mild conditions. The objective of this research is not only to decrease the costs associated with the dehydrogenation of alkane process, but also to contribute to the development of greener routes to bond formation as well as to get a better understanding of the transformations occurring at the active site of enzymes.

长期以来，大自然一直是科学家和艺术家的灵感源泉。世界上数百万人所熟悉的一些设计最巧妙的产品和小工具，其起源都是源于植物和野生动物中看似简单的形状和图案。虽然我们最近学到了很多关于大自然如何进行各种有效的化学转化的信息，但生物系统是复杂的，还远远没有被完全理解。这种复杂系统的一个例子是大自然将大气中的氮转化为氨的温和方式。100年来，氨一直是通过Haber-Bosch工艺从氮气和氢气中生产出来的，这种技术需要非常苛刻的条件（350-550°C, 150-350 atm）。相比之下，在自然界中发现的一些被称为氮酶的酶能够在环境温度和压力下轻松实现这种转化。与强氮三键断裂的情况一样，碳氢化合物中强碳氢键的受控活化和功能化仍然是一个挑战。绝大多数珍贵的原材料，如液态和气态碳氢化合物，只是作为加热和运输的燃料而燃烧，只有一小部分含有碳-氢键的分子（烷烃和芳烃）被大规模转化为化学中间体，用于化学工业。