CAREER: Revolutionizing sulfur removal in transportation fuels via adsorption in ion exchanged zeolites

政府和行业发布的强制性标准要求将运输燃料(如汽油、柴油和喷气燃料)中的硫降低到接近零的水平。加氢脱硫(HDS)是被广泛接受的用于脱除燃料中硫的商业炼油技术。尽管HDS对于这一目的是有效的，但它也是能源密集型的，特别是在炼油厂试图满足更严格的硫磺监管标准的情况下。该项目将建立一个新的技术平台和相关的基础科学，以开发环境友好型“过滤器”，在环境条件下高效和经济地吸附脱除液态碳氢燃料(ADS)。这种“过滤器”将是便携的、紧凑的、可再生的，最终可能被集成到汽车发动机或加油站。这些脱硫“过滤器”的成功设计将减少基于燃烧的硫排放、能源需求和燃料脱硫成本，从而改变燃料加工行业。实现无硫燃料具有广泛的人类健康和环境影响；因此，这项研究的结果也有可能有益于国家健康和繁荣。拟议的ADS工艺将基于称为离子交换沸石的多孔矿物。预计ADS工艺将与现有的HDS工艺相结合，专门针对特别难降解的含硫分子。通过这种方法，燃料中的硫含量可以达到超低水平。该项目将致力于开发一种综合的实验和模拟方法，以研究离子交换沸石的内在性质与其作为硫分子“过滤器”的性能之间的相关性。通过开发一个创新的班级，将把研究和教育结合到该项目中，该班级将通过服务学习教学法将学生培养成社区参与的学者，甚至是政策制定者。PI的长期职业目标是为清洁燃料生产创造新的材料和工艺。为了实现这一目标，本项目的主要研究目标是促进离子交换沸石用于ADS过程的基础科学。沸石分子筛因其活性中心、高比表面积和孔道结构而成为优良的分子筛。然而，要将沸石转化为有效的硫吸附剂，需要解决以下研究挑战：(1)扩散沸石的孔必须足够大，以容纳空间位阻的硫分子；(2)容量和选择性-沸石活性中心需要具有高容量并选择性地吸附硫分子(保持碳氢化合物中剩余的芳香族分子不变)；以及(3)可行性和寿命-该过程应该是自发的，沸石分子筛应该是可再生和可重复使用的。为了应对这些挑战，将开发一种动态学习方法，将材料定制和表征、使用模型燃料中的硫模型化合物进行ADS测试以及数据科学相结合。这一方法将是实验和建模之间的迭代过程，并将创造关于金属和双金属交换的Y沸石的性质如何影响ADS过程的基础知识，如孔径、金属性质、位置、氧化状态和相互作用。研究的结果将是指导预测和设计ADS的最佳沸石的基础知识。然后，将使用真实的燃料，即汽油、喷气燃料和柴油对最佳沸石进行测试。这一奖项反映了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。

Mandatory government- and industry-issued standards require the reduction of sulfur in transportation fuels (e.g., gasoline, diesel, and jet fuels) to near-zero levels. Hydrodesulfurization (HDS) is the widely-accepted commercial refinery technology used for the removal of sulfur in fuels. Although HDS is effective for this purpose, it is also energy intensive, particularly as refineries attempt to meet tighter regulatory standards of sulfur. This project will establish a new technological platform and associated fundamental science enabling the development of environment-friendly "filters" for the efficient and cost-effective adsorptive desulfurization (ADS) of liquid hydrocarbon fuels at ambient conditions. Such "filters" will be portable, compact, and regenerable and may eventually be integrated into vehicle engines or gas stations. Successful design of these desulfurization "filters" will transform the fuel processing industry by reducing combustion-based sulfur emissions, the energy requirements, and the cost of fuel desulfurization. Achieving sulfur-free fuels has widespread human health and environmental implications; thus, the results of this research also have the potential to benefit national health and prosperity. The proposed ADS process will be based on porous minerals, called ion-exchanged zeolites. It is expected that the ADS process will be combined with existing HDS processes to specifically target the sulfur-containing molecules that are particularly difficult to degrade. Through this approach, ultra-low sulfur levels in fuels can be reached. This project will focus on developing an integrated experimental and modeling methodology to investigate correlation of the intrinsic properties of the ion-exchanged zeolites and their performance as a sulfur molecule "filter." Research and education are integrated in the project through the development of an innovative class that will train the students to become community-engaged scholars and even policy makers through a service learning pedagogy. The PI's long-term career goal is to create novel materials and processes for clean fuels production. Toward this goal, the overarching research objective for this project is to advance the fundamental science of ion-exchanged zeolites for use in the ADS process. Zeolites are excellent molecular sieves due to their active sites, high surface area, and porous structure. However, to transform zeolites into effective sulfur sorbents, the following research challenges need to be addressed: (1) diffusion - zeolite pores need to be large enough to accommodate the sterically hindered sulfur molecules; (2) capacity and selectivity - zeolite active sites need to have high capacity and adsorb sulfur molecules selectively (leaving the rest of the aromatic molecules in the hydrocarbons intact); and (3) feasibility and lifetime - the process should be spontaneous, and the zeolites regenerative and reusable. To address these challenges, a dynamic-learning methodology will be developed that integrates materials tailoring and characterization, ADS testing using sulfur model compounds in model fuels, and data science. This methodology will be an iterative process between experiments and modeling and will create fundamental knowledge on how the properties of metal and bimetal-exchanged Y zeolites, such as pore size, metals properties, location, oxidation state and interaction, affect the ADS process. The outcome of the study will be fundamental knowledge leading to the prediction and design of optimum zeolites for ADS. The optimum zeolite will then be tested using real fuels, namely gasoline, jet fuel, and diesel.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.