Bioinspired and Sustainable Catalysis for Chlorite Conversion and Dioxygen Reduction

在这个由化学系化学催化计划资助的项目中，普渡大学的Mahdi Abu-Omar教授正在开发催化剂，通过更绿色的工艺制造重要的化学品。催化剂是一种试剂，可以加速和引导反应生成所需的产品，而不会消耗自身。一个很受欢迎的例子是汽车中的催化转化器，它减少了某些气体的排放，如一氧化碳，使车辆的污染显著减少。催化剂通常以稀有和昂贵的贵重元素为基础，如铂和铑。相比之下，生物催化剂或酶往往使用丰富而廉价的元素，如铁和铜来进行重要的生理反应。阿布-奥马尔教授正在从生物学中获得灵感，开发和研究基于锰和铁的催化剂，这些元素富含地球上丰富的元素，用于对能源和环境至关重要的化学反应：直接从空气中制造过氧化氢，将由氯和氧原子组成的环境污染物分解成无害的盐和氧气，并根据需要在水中和室温下将这种污染物转化为消毒剂。阿布-奥马尔教授正在开发第一排过渡金属的高价氧配合物，特别是锰和铁，由考拉尔、卟啉和吡啶或酰胺大环配体支撑。其中一些配合物正被用于研究锰(V)-氧代钴中质子耦合电子转移(PCET)的动力学和机理，以建立一个选择性地将双电子还原为过氧化氢的催化体系。直接从空气中产生过氧化氢将为制造这种重要的工业化学品提供更环保的方法，并有助于可再生能源转换和储存的战略。这些络合物中的其他一些正被用于研究氧阴离子亚氯酸盐的反应化学性质。阿布-奥马尔教授正在开发催化剂，通过在第二配位球中加入氢键口袋，将亚氯酸盐选择性地歧化为氧气和无毒的氯。通过对催化分解亚氯酸盐的机理和活性口袋的结构和功能特征的计算研究，指导了栅栏卟啉配体的设计。人们正在研究铁非血红素催化剂，用于在常温和非腐蚀性条件下从亚氯酸盐按需生产二氧化氯。二氧化氯用于纸浆漂白以及消毒和净水。这项研究的其他更广泛的影响包括为一群高中生和高中和中学教师开展外联活动，向他们介绍可持续催化科学。

In this project funded by the Chemical Catalysis Program of the Chemistry Division, Professor Mahdi Abu-Omar of Purdue University is developing catalysts to make important chemicals via greener processes. Catalysts are reagents that accelerate and direct reactions toward desirable products without themselves being consumed. A popular example is the catalytic converter in automobiles, which reduces certain gaseous emissions such as carbon monoxide and renders vehicles significantly less polluting. Often catalysts are based on precious elements that are rare and expensive such as platinum and rhodium. In contrast, biological catalysts or enzymes, often use abundant and inexpensive elements such as iron and copper to carry out important physiological reactions. Professor Abu-Omar is drawing inspiration from biology to develop and study catalysts based on manganese and iron, earth-abundant elements, for chemical reactions that are important for energy and the environment: making hydrogen peroxide directly from air, decomposing an environmental contaminant made up of chlorine and oxygen atoms into harmless table salt and oxygen, and also converting this contaminant into a disinfectant on-demand in water and at room temperature. Professor Abu-Omar is developing high-valent oxo complexes of first row transition metals, specifically manganese and iron, supported by corrole, prophyrin, and pyridyl or amidato macrocylic ligands. Some of these complexes are being used to study the kinetics and mechanism of proton coupled electron transfer (PCET) in manganese(V)-oxo corrole to establish a catalytic system for the selective two-electron reduction of dioxygen to hydrogen peroxide. Generation of hydrogen peroxide directly from air would provide greener methods for making this important industrial chemical and contribute to strategies for renewable energy conversion and storage. Others of these complexes are being used to study the reaction chemistry of the oxyanion, chlorite. Professor Abu-Omar is developing catalysts for the selective dismutation of chlorite to dioxygen and innocuous chloride by incorporating a hydrogen bonding pocket in the second-coordination sphere. Picket fence porphyrin ligand designs are being guided by computational investigations into the mechanism of catalytic chlorite decomposition and the structural and functional features of the active pocket. Iron non-heme catalysts are being studied for the production of chlorine dioxide on-demand from chlorite under ambient temperature and noncorrosive conditions. Chlorine dioxide is used in pulp bleaching as well as in disinfection and water purification. Other broader impacts of the research include outreach activities for a group of high school students and high and middle school teachers to introduce them to sustainable catalysis science.