Collaborative Research: Manufacturing of Hollow Particles with Encapsulated Active Sites for Use as Nanoreactors

该项目通过开发一种简单的过程来控制纳米结构颗粒设计，从而产生新的技术和基本概念，从而导致科学进步和经济进步。纳米制造工艺致力于设计具有可控壳孔结构的中空颗粒，这些结构固有地用于对能源、环境和医疗保健部门至关重要的技术中。中空纳米颗粒的内部体积用于包裹材料或在受限环境中进行反应。由于在催化、气敏和药物输送方面的应用，这种中空颗粒的可用性引起了人们的极大兴趣。该奖项专注于一步合成方法，用于大规模制造功能空心颗粒，使用停留时间较短的半连续气雾剂工艺。这项技术的新颖性不仅在于能够产生中空颗粒，还在于能够在其中封装功能纳米颗粒。这类材料包括壳体，它作为封装的金属/金属氧化物的载体，这些金属/金属氧化物充当对化学和能源工业至关重要的化学品的精密合成的催化剂。这是纳米级的过程强化，即进入含有催化材料的中空颗粒的化学物种有时间进行广泛的反应，从而实现高效的反应和化学合成。这项研究成果惠及众多依赖催化的行业，造福国民经济和社会。这些研究成果被整合到一门为本科生和研究生设计的新课程中，该课程将材料制造、反应工程和工业实践联系起来。在过程技术方面向K-12和社区学院的学生进行宣传是教育活动的一个方面。这项工作背后的科学概念是在气溶胶液滴通过加热区的受限体积内合成陶瓷材料的液滴中的化学。当应用于模板化介孔二氧化硅合成时，二氧化硅从液滴表面向内生长。盐桥接剂的引入导致结构导向的有机模板在内部积累，导致模板关闭，并为二氧化硅的向内推进提供障碍，从而导致在焙烧时生成含有中空陶瓷的金属氧化物。该项目的重点是对这一想法的理解和进一步发展，以及在中空颗粒中包括催化活性中心，如沸石。该项目研究控制这些材料性能的方法，包括壳层厚度和介孔，以产生轻质陶瓷。它们在两个主要应用方面的有效性，(A)氯化环境污染物的还原脱氯和(B)非氧化性甲烷偶联反应作为环境修复和催化的例子被研究。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。

This project generates new technology and fundamental concepts through the development of a facile process to control nanostructured particle design leading to scientific advancement and economic progress. The nanomanufacturing process addresses the design of hollow particles with controlled shell-pore structures of inherent use in technologies vital to the energy, environment and healthcare sectors. The interior volume of the hollow nanoparticles is used to encapsulate materials or conduct reactions in confined environments. The availability of such hollow particles is of great interest due to applications in catalysis, gas sensing, and pharmaceuticals delivery. This award focusses on a one-step synthesis method for the large-scale manufacturing of functional hollow particles, using a semi-continuous aerosol-based process with short residence times. The novelty of this technology is the ability not just to generate hollow particles, but also to encapsulate functional nanoparticles within them. Such materials include the shell which acts as the support for the encapsulated metals/metal-oxides which serve as catalysts for the precision synthesis of chemicals vital to the chemical and energy industries. This is process intensification at the nanoscale, where chemical species entering the hollow particles containing catalytic materials, have time to react extensively leading to highly efficient reaction and chemical synthesis. The results of this research benefits many industries that rely on catalysis, which benefits national economy and society. The research findings are integrated in a new course designed for undergraduate and graduate students, linking materials manufacturing, reaction engineering and industrial practice. Outreach to K-12 and community college students in process technology are aspects of the educational activities. The scientific concept behind the work is the chemistry-in-a-droplet aspect of ceramic materials synthesis in the confined volume of an aerosol droplet passing through a heated zone. When applied to templated mesoporous silica synthesis, the silica grows inwards from the surface of the droplet. Introduction of a salt bridging agent leads to accumulation of a structure-directing organic template in the interior, leading to the shut-down of templating and providing a barrier to inward progression of the silica thus leading to a metal oxide containing hollow ceramic upon calcination. The project focuses on the understanding and further development of this idea and the inclusion of catalytic active sites, such as zeolites, within the hollow particles. The project investigates methods to control the properties of these materials, including shell thickness and mesoporosity to generate lightweight ceramics. Their effectiveness on two major applications, (a) the reductive dechlorination of chlorinated environmental contaminants and (b) the non-oxidative methane coupling reaction are studied as examples in environmental remediation and catalysis.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.