EFRI DCheM: Precise but Tunable Reactions Through Tunably Precise Surfaces

EFRI DCheM：通过可调节精确表面实现精确但可调节的反应

• 批准号: 2029359
• 负责人: William Epling
• 金额: $ 200万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2029359&HistoricalAwards=false
• 关键词: EFRI; DCheM; Precise; but; Tunable

The use of geographically distributed resources such as biomass, stranded natural gas, biogas and municipal solid waste for localizable, clean chemical manufacturing has the potential to transform the U.S. domestic manufacturing landscape. However, those resources are typically produced in relatively small quantities that make their collection and transport to large centralized chemical plants impractical and often uneconomical. In addition, the centralized plants – because of their size – are constrained to operating under steady conditions with little flexibility with respect to process conditions, feedstock variability, and end products. In contrast, small-scale reactor systems relax such constraints and therefore, the smaller scale of distributed chemical manufacturing (DCheM) systems offers new opportunities to change operating conditions rapidly to increase processing efficiency and respond to feedstock variability. The overarching goal of the project is thus to develop a radically new approach to catalytic reactor design by modulating reactor operating parameters to achieve improved rates, product selectivity, and catalyst lifetime. The project focuses on valorizing methane and ethane, the main components of natural gas, but the concept of transiently-operated, flexible, small-scale reactors that can convert distributed feedstocks of different qualities to higher-value liquid products is broadly applicable. The development of such reactors opens the door to point-of-source chemical processing of abundant resources distributed throughout the U.S., thereby transforming regional economies as well as the overall chemical manufacturing landscape.The project introduces a new dynamically-oscillated catalytic reactor that periodically modulates the reacting gas environment about a catalytic site. The goal is to identify – at a fundamental level – catalytic reactor design and operating parameters that improve rates, selectivity, and catalyst longevity beyond levels accessible in steady-state operation. Methane oxidative reforming (MOR) and ethane oxidative dehydrogenation (EODH) are chosen as two probe reactions, both having tunable reaction chemistry between exothermic/endothermic operating conditions. To demonstrate the enhanced performance, the coverage dependence of fundamental surface processes during the oxidation and reduction catalytic half-cycles for MOR will be characterized via density functional theory (DFT), ab-initio molecular dynamics (AIMD), and kinetic Monte Carlo (kMC) methods. This will be coupled with ultrasensitive experimental temporal analysis of products (TAP) to reveal surface transients that diverge from classical steady-state reaction rate kinetics. The resolution of the temporal steps will describe operation through new reaction pathways that utilize externally induced periodic feed modulations. The effect of modulation will be demonstrated experimentally in micro- and monolithic-reactors coupled with in situ techniques to demonstrate pathways to rate/selectivity and longevity enhancements. Finally, a reactor-scale model will be built to unify the experiments and theory by describing reactor performance and predicting optimal dynamical operating conditions. Collectively, the combined experimental-computational approach pro-posed here will establish a new strategy for heterogeneous catalysis and push beyond the conventional steady-state thermodynamic/kinetic limits manifested in the Sabatier volcano by using innovative reaction engineering concepts. The project will include education and outreach activities emphasizing opportunities for underrepresented student groups. To this end, the project will engage a collaborator to coordinate diversity workshops that will engage all of the project researchers. The collaborator will also recruit underrepresented minority students through attending conferences targeted at promoting diversity in STEM education and workforce development.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.

利用生物质、滞留天然气、沼气和城市固体废物等地理上分布的资源进行本地化的清洁化学品制造，有可能改变美国国内的制造业格局。然而，这些资源通常以相对小的数量生产，这使得它们的收集和运输到大型集中式化工厂不切实际并且通常不经济。 此外，集中式工厂-由于其规模-被限制在稳定条件下运行，在工艺条件、原料可变性和最终产品方面几乎没有灵活性。 相比之下，小规模反应器系统放宽了这些限制，因此，较小规模的分布式化学制造（DCheM）系统提供了快速改变操作条件以提高加工效率并响应原料变化的新机会。 因此，该项目的总体目标是通过调节反应器操作参数来开发一种全新的催化反应器设计方法，以提高反应速率、产品选择性和催化剂寿命。该项目的重点是稳定天然气的主要成分甲烷和乙烷，但可以将不同质量的分布式原料转化为更高价值的液体产品的瞬时操作，灵活，小型反应器的概念是广泛适用的。这种反应器的发展为分布在美国各地的丰富资源的源点化学处理打开了大门，该项目引入了一种新型动态振荡催化反应器，该反应器周期性地调节催化场所周围的反应气体环境。其目标是确定-在一个基本的水平-催化反应器的设计和操作参数，提高速率，选择性，和催化剂寿命超过在稳态操作中可达到的水平。 甲烷氧化重整（莫尔）和乙烷氧化脱氢（EODH）被选择作为两个探针反应，两者在放热/吸热操作条件之间具有可调的反应化学。为了证明增强的性能，在氧化和还原催化半周期的莫尔的基本表面过程的覆盖依赖性将通过密度泛函理论（DFT），从头算分子动力学（AIMD），和动力学蒙特卡罗（kMC）方法的特点。这将是再加上超灵敏的实验时间分析的产品（TAP），以揭示表面瞬态偏离经典的稳态反应速率动力学。时间步骤的分辨率将描述通过利用外部诱导的周期性进料调制的新反应途径的操作。调制的效果将在微型和整体反应器中进行实验证明，并结合原位技术，以证明速率/选择性和寿命增强的途径。最后，将建立反应器规模模型，通过描述反应器性能和预测最佳动态操作条件来统一实验和理论。总的来说，这里提出的实验-计算相结合的方法将建立一个新的多相催化策略，并通过使用创新的反应工程概念，超越传统的稳态热力学/动力学极限。 该项目将包括教育和外联活动，强调为代表性不足的学生群体提供机会。 为此，该项目将聘请一名合作者协调多样性研讨会，让所有项目研究人员参与。合作者还将通过参加旨在促进STEM教育和劳动力发展多样性的会议来招募代表性不足的少数民族学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估而被认为值得支持。