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

强制性的政府和行业发布的标准要求减少运输燃料中的硫（例如，汽油、柴油和喷气燃料）降至接近零的水平。加氢脱硫（HDS）是广泛接受的商业炼油厂技术，用于脱除燃料中的硫。尽管HDS在这方面是有效的，但它也是能源密集型的，特别是当炼油厂试图满足更严格的硫监管标准时。该项目将建立一个新的技术平台和相关的基础科学，从而能够开发环境友好的“过滤器”，以便在环境条件下对液态烃燃料进行高效和具有成本效益的吸附脱硫。这种“过滤器”将是便携式的、紧凑的和可再生的，并且最终可能被集成到车辆发动机或加油站中。这些脱硫“过滤器”的成功设计将通过减少基于燃烧的硫排放、能源需求和燃料脱硫的成本来改变燃料加工行业。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利于国家的健康和繁荣。拟议的ADS工艺将基于多孔矿物，称为离子交换沸石。预计ADS工艺将与现有的HDS工艺相结合，专门针对特别难以降解的含硫分子。通过这种方法，可以达到燃料中的超低硫含量。该项目将集中于开发一种综合的实验和建模方法，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。“通过开发一个创新课程，将研究和教育纳入该项目，该课程将通过服务学习教学法培训学生成为参与社区的学者甚至决策者。PI的长期职业目标是为清洁燃料生产创造新材料和工艺。为了实现这一目标，该项目的总体研究目标是推进用于ADS过程的离子交换沸石的基础科学。沸石分子筛是一种优良的分子筛，具有高的比表面积、高的活性中心和多孔结构.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-沸石孔需要足够大以容纳空间位阻的硫分子;（2）容量和选择性-沸石活性位点需要具有高容量并选择性地吸附硫分子（使烃中的其余芳族分子保持完整）;和（3）可行性和寿命-该方法应该是自发的，并且沸石是可再生的和可重复使用的。为了应对这些挑战，将开发一种动态学习方法，该方法将材料定制和表征、在模型燃料中使用硫模型化合物的ADS测试以及数据科学集成在一起。该方法将是实验和建模之间的迭代过程，并将创建关于金属和双金属交换Y沸石的性质如何影响ADS过程的基础知识，例如孔径、金属性质、位置、氧化态和相互作用。该研究的结果将是基础知识，导致预测和设计的最佳分子筛的ADS。最佳沸石将使用真实的燃料进行测试，即汽油，喷气燃料和柴油。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.