Understanding and Exploiting the Favorable Role of Non-Stoichiometric Oxygen in Bulk Metal Oxide Catalyzed Partial Oxidation of Light Alkanes

我国向清洁能源的过渡需要更有效地利用化石燃料，同时过渡到通过太阳能或风能发电等替代能源产生的可持续或生物可再生燃料。目前的化学品市场严重依赖于乙烯--从乙烷(从天然气中)蒸汽裂解产生的乙烯--来生产各种商品化学品。蒸汽裂解是一种能源密集型工艺。该项目探索了一种通过乙烷氧化脱氢(ODHE)生产乙烯的替代工艺，能耗较低。氧气的受控引入--以促进乙烯生产的方式，而不会更深地氧化成一氧化碳(CO)和二氧化碳(CO2)等废物--一直是ODHE技术商业化引入的主要障碍。该项目通过探索一种新的催化方法来解决这一技术差距，以提高乙烯产量，同时降低能源消耗。新的催化剂合成技术将与反应工程概念相结合，以实现最佳的氧气供应。除了促进清洁能源过渡，该项目还包括教育和外联工作，提高人们对与碳排放和气候影响有关的清洁能源必要性的认识，同时还培训未来的科学家和工程师。在低碳烷烃ODH中引入过量的非化学计量比氧，虽然有利于产生放热和降低反应温度，但由于与产生CO和CO2相关的较低的烯烃选择性，传统上一直被避免。该项目寻求块体金属氧化物催化剂研究和设计的范式转变，通过证明和开发存在的氧的潜在有利作用超过金属氧化物催化剂化学计量比所规定的作用。评估氧化物表面活性中心要求的新方法，包括一系列动力学、同位素和光谱工具，以评估非化学计量比氧的机械功能，将与先进的合成策略相结合，通过控制掺杂分布和晶体习惯来操纵表面氧部分的催化功能。这种协同方法结合了机理研究和熔盐合成等先进的结晶技术，虽然只适用于氧化镍催化的ODHE，但可能被证明广泛适用于具有工业意义的高温催化部分氧化反应。作为拟议工作的一部分而开发的催化剂可以为廉价、节能的乙烯生产方法奠定基础，因为与传统工艺相比，操作温度要低得多。调查人员将把这些研究的结果用于他们机构的研究生课程，同时继续在休斯顿地区正在进行的STEM外联活动，包括休斯顿大学能源日和雪佛龙女孩工程未来日，为高中生提供实践研究经验(项目ACS种子)，并指导本科生研究人员。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。

Our Nation’s transition to clean energy requires more efficient utilization of fossil fuels combined with a transition to sustainable or biorenewable fuels generated through alternative energy sources such electricity produced from solar or wind energy. The current chemical market relies heavily on ethene – produced from the steam cracking of ethane (from natural gas) - to manufacture a wide range of commodity chemicals. Steam cracking is an energy-intensive process. The project explores an alternative, less energy-intensive, process for ethene manufacture via the oxidative dehydrogenation of ethane (ODHE). Controlled introduction of oxygen – in ways that promote ethene production without deeper oxidation to waste products such as carbon monoxide (CO) and carbon dioxide (CO2) – has been a major impediment to the commercial introduction of ODHE technology. The project addresses this technology gap by exploring a novel catalytic approach for enhancing ethene production while decreasing energy consumption. New catalyst synthesis techniques will be combined with reaction engineering concepts to achieve optimal supply of oxygen. In addition to facilitating the clean energy transition, the project includes educational and outreach efforts that raise awareness of the need for clean energy as related to carbon emissions and climate impact, while also training future scientists and engineers. Introduction of excess, non-stoichiometric oxygen in light-alkane ODH, while favorable for producing exothermicity and lowering the reaction temperature, has traditionally been avoided due to lower olefin selectivity associated with production of CO and CO2. The project seeks a paradigm shift in the study and design of bulk metal oxide catalysts by evidencing and exploiting a potentially favorable role of oxygen present in excess of that stipulated by metal oxide catalyst stoichiometry. Novel methods for assessing active site requirements on oxide surfaces, involving a range of kinetic, isotopic, and spectroscopic tools to assess the mechanistic function of non-stoichiometric oxygen, will be combined with advanced synthetic strategies for manipulating the catalytic function of surface oxygen moieties through control over dopant distribution and crystal habit. This synergistic approach - combining mechanistic investigations and advanced crystallization techniques such as molten salt syntheses - although applied specifically to nickel oxide catalyzed ODHE, may prove broadly applicable to high temperature catalytic partial oxidation reactions of industrial importance. Catalysts developed as part of the proposed work could form the basis for an inexpensive, energy-efficient route to producing ethene due to significantly lower operation temperatures compared to conventional processes. The investigators will use the findings of these studies in graduate-level courses at their institution, while continuing on-going STEM outreach activities in the Houston area including UH Energy Day and Chevron Girls Engineering the Future Day, providing high school students with hands-on research experience (Project ACS SEED), and mentoring undergraduate researchers.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.