Understanding Liquid Phase Tandem Catalysis on Zeolite Encapsulated Metal Nanoparticles

生物质正在成为燃料和化学品可再生制造的日益重要的能源来源。然而，生物质原料是复杂的，它们转化为高价值燃料和化学产品在很大程度上依赖于催化来加速化学反应和促进所需产品的形成。该项目将探索能够串联催化的新型催化剂设计，即催化剂的结构使得它们可以在单个催化反应器中按特定顺序执行多个反应步骤。串联催化比基于连续反应器的传统工艺效率更高，涉及的资本成本更低，后者通常需要在反应器之间进行昂贵的分离步骤。到目前为止，大多数关于串联催化的研究都是在个案的基础上针对特定的燃料或化学产品进行的。这项研究的重点是开发通用的设计指南，以促进串联催化在整个化工制造和燃料精炼行业中更快、更广泛地采用。这项工作将有助于美国在特种化学品、药品、平台燃料和商品化学等领域的化学和燃料制造方面的领先地位。拟议工作的总体目标是开发沸石包裹金属(M@沸石)催化剂的设计原则，以实现选择性液相串联反应，其中包括：1)合成和表征具有可控中心密度和分布的M@沸石催化剂；2)了解M@沸石催化剂中的溶剂效应和限制效应对速率和选择性的影响；3)建立活性中心的结构、位置分布和局部环境与串联反应性能之间的关联。该项目将利用一种新的阳离子聚合物辅助合成策略来制备M@沸石催化剂，并利用研究人员实验室最近开发的液相技术表征其性质和活性中心密度。特别是，将确定M@沸石分子筛晶体中酸中心的分布。这项研究将通过动力学和光谱研究相结合的方法，通过测定本征活化能来阐明溶剂和限制对M@沸石上的模型液相反应的影响。以一锅串联反应为模型反应，考察了M@沸石分子筛晶体中酸中心的密度和分布对串联催化过程和催化剂失活的影响。在教育方面，调查员将开发一个项目，向高中生和本科生介绍3D打印技术的基础知识，作为一项动手活动，以激发人们对STEM相关职业机会的兴奋，特别是对背景较少的学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Biomass is becoming an increasingly important source of energy for the renewable manufacturing of fuels and chemicals. Biomass feedstocks are complex, however, and their conversion to high-value fuel and chemical products relies heavily on catalysis to accelerate chemical reactions and promote the formation of desired products. The project will explore novel catalyst designs that are capable of tandem catalysis, that is, catalysts structured such that they can carry out multiple reaction steps in a specific order in a single catalytic reactor. Tandem catalysis is more efficient and involves lower capital costs than traditional processes based on sequential reactors, which often carry the need for costly separation steps between reactors. To date, most research related to tandem catalysis has been done on a case-by-case basis targeting specific fuels or chemical products. This study focuses on developing generalized design guidelines that will promote faster and wider-scale adoption of tandem catalysis throughout the chemical manufacturing and fuel refining industries. The work will contribute to U.S. leadership in chemical and fuels manufacturing in areas as diverse as specialty chemicals, pharmaceuticals, and platform fuels and commodity chemicals.The overarching goal of the proposed work is to develop design principles for zeolite encapsulated metal (M@zeolite) catalysts to enable selective liquid phase tandem reactions, which include: 1) synthesize and characterize M@zeolite catalysts with controlled site density and distribution; 2) understand the solvent effect and the confinement effect in M@zeolite catalysts on rates and selectivities; and 3) establish correlations of the architecture, site distribution, and local environment of active sites with performance in tandem reactions. The project will leverage a novel cationic polymer assisted synthetic strategy to prepare M@zeolite catalysts, and characterize their properties and density of active sites with liquid phase techniques recently developed in the investigator's laboratory. In particular, the distribution of acid sites in the zeolite crystals of M@zeolite will be determined. The study will elucidate solvent and confinement effects on model liquid phase reactions over M@zeolite via a combination of kinetic and spectroscopic investigations by determining intrinsic activation energies. One-pot tandem reactions to upgrade furfural to C8 oxygenates/hydrocarbons, as well as pentanoic acid, will be employed as model reactions to investigate the impact of the density and distribution of acid sites in the zeolite crystal of M@zeolite on tandem catalytic processes and catalyst deactivation. On the educational front, the investigator will develop a program to introduce the basics of 3D printing technology to high school and undergraduate students as a hands-on activity to stimulate excitement about STEM related career opportunities, especially for students from underrepresented backgrounds.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.