NSF-DFG Echem: CAS: Electrochemical Pyrrolidone Synthesis: An Integrated Experimental and Theoretical Investigation of the Electrochemical Amination of Levulinic Acid (ElectroPyr)

当今的化工、能源和交通运输行业日益面临化石资源枯竭的问题。此外，人为气候变化与化石石油、天然气和煤炭的利用密切相关。对于后代来说，对工业应用的可再生碳源进行评估并避免二氧化碳排放的进一步增加具有重要意义。生物质是一种前景看好的可再生碳源，具有创造封闭碳循环的潜力，二氧化碳净排放量为零。在NSF化学部的资助下，加州大学洛杉矶分校的Philippe Sautet教授与RWTH-Aachen的德国同事合作，正在开发基于生物的精细化学品路线。可再生能源(太阳能、风能等)已经产生了过剩的电力，而将可再生原材料电化学转化为精细化学品或燃料添加剂是合理利用这些过剩电力的一种方式。选择的反应物，乙酰丙酸，是美国能源部确定的12种最有希望的平台化学品之一。该项目的重点是将其电化学转化为吡咯烷酮，这是制药产品、溶剂和聚合物的重要中间体。总体而言，与化学催化相比，电化学使反应条件更温和，并提供了将可再生电能整合到化学价值链中的潜力。在建议的吡咯烷酮合成的情况下，可以避免高氢压，并投射水电解质以促进沿生物精炼价值链的整合。除了研究成果对可持续经济和气候的更广泛的社会经济影响外，美国和德国研究团队之间的国际合作将为参与研究的学生提供独特的文化和教育体验。该项目旨在对乙酰丙酸电化学胺化生产吡咯烷酮进行综合实验和理论研究。Sautet小组将专注于电催化表面反应的第一性原理模拟，旨在全面了解机理。RWTH-Aachen小组将对转化进行实验研究，重点研究电催化剂和工艺参数的影响。该项目可能会提高人们对电化学胺化机理的基本理解。这也将为控制电催化剂的催化表面反应性的因素提供关键的见解。最后，对主要工艺参数进行了实验研究。这项研究的主要目的是让协作团队进行详细的机械性调查。为此，将分别考虑可分为三个子步骤的反应。首先从计算和实验两个方面研究亚胺在模型底物上的生成，然后电催化加氢生成胺，最后缩合成吡咯烷酮。所提出的反应途径将通过详细的机理研究来检验，并将通过与模型底物的比较来进一步研究。例如，丙酮是第一步和第二步反应的合适模型化合物。然而，通过改变链长以及相应模型底物中存在的官能团的扩展，将提供更深层次的实验见解。此外，所有的实验研究都将伴随着电极材料和反应条件的优化。将根据动力学模型和比例关系对不同的电催化剂进行计算筛选。这项研究是在NSF-DFG领导机构电合成和电催化活动(NSF-DFG eChem)机会NSF 20-578下资助的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Today's chemical, energy, and transportation industry is increasingly confronted with a depletion of fossil resources. In addition, anthropogenic climate change is strongly related to utilization of fossil oil, gas, and coal. For later generations, it is of major importance to valorize renewable carbon sources for industrial applications and avoid further increase of CO2 emissions. Biomass presents a promising renewable carbon source bearing the potential to create closed carbon cycles, with net zero CO2 emissions. With funding from the NSF Division of Chemistry, Professor Philippe Sautet of the University of California-Los Angeles, in collaboration with German colleagues at the RWTH-Aachen, is developing bio-based routes to fine chemicals. Renewable energy sources (solar, wind, etc.) already generate an excess of electricity and the electrochemical conversion of renewable raw materials into fine chemicals or fuel additives is one way of making sensible use of this excess. The chosen reactant, levulinic acid, is one of the twelve most promising platform chemicals identified by the US Department of Energy. The project focuses on its electrochemical transformation into pyrrolidones, important intermediates for pharmaceutical products, solvents, and polymers. In general, electrochemistry enables milder reaction conditions compared to chemocatalysis and provides the potential to integrate renewable electrical energy into chemical value chains. In the case of the proposed pyrrolidone synthesis, high hydrogen pressure can be avoided, and aqueous electrolytes are projected to facilitate an integration along the bio-refinery value chain. In addition to the broader socioeconomic impacts of the research outcomes on a sustainable economy and on climate, the international collaboration between the US and German research teams will provide the students involved in the research with a unique cultural and educational experience.The project aims for an integrated experimental and theoretical investigation of the electrochemical amination of levulinic acid to produce pyrrolidones. The Sautet group will focus on first-principle simulations of the electrocatalytic surface reaction aiming for a comprehensive mechanistic understanding. The RWTH-Aachen group will experimentally investigate the transformation with emphasis on the influence of electrocatalyst and process parameters. The project will likely improve fundamental understanding of the mechanism of electrochemical amination. It will also provide key insights into the factors controlling catalytic surface reactivity of the electrocatalyst. Finally, major process parameters will be explored experimentally. The major objective of this study is for the collaborative team to conduct a detailed mechanistic investigation. For this purpose, the reaction, which can be divided into three sub-steps, will be considered separately. First, the imine formation on model substrates, then the electrocatalytic hydrogenation to the amine and finally the condensation to the pyrrolidone will be investigated both computationally and experimentally. The proposed reaction pathway will be examined by detailed mechanistic studies and will be further investigated by comparison with model substrates. Acetone, for example, is a suitable model compound for the first and second reaction steps. However, deeper experimental insights will be given by variation of the chain length as well as expansion of the functional groups present in the corresponding model substrates. Moreover, all experimental investigations will be accompanied by an optimization of the electrode material and the reaction conditions. A computational screening of different electrocatalysts will be performed, based on kinetic modelling and scaling relations.This research was funded under the NSF-DFG Lead Agency Activity in Electrosynthesis and Electrocatalysis (NSF-DFG EChem) opportunity NSF 20-578.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.