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

该项目通过开发一个简单的过程来控制纳米结构粒子的设计，从而促进科学进步和经济发展，从而产生新的技术和基本概念。纳米制造工艺解决了具有受控壳孔结构的中空颗粒的设计问题，这些空心颗粒在能源、环境和医疗保健部门至关重要的技术中具有固有的用途。中空纳米颗粒的内部体积用于封装材料或在密闭环境中进行反应。由于在催化、气体传感和药物输送方面的应用，这种空心颗粒的可用性引起了极大的兴趣。该奖项的重点是一步合成方法，用于大规模制造功能性中空颗粒，使用半连续气溶胶为基础的工艺，停留时间短。这项技术的新颖之处在于，它不仅能够产生中空颗粒，而且还能将功能纳米颗粒封装在其中。这类材料包括外壳，外壳作为封装金属/金属氧化物的支撑，金属氧化物作为催化剂，用于精密合成对化学和能源工业至关重要的化学品。这是纳米级的过程强化，化学物质进入含有催化材料的空心颗粒，有时间进行广泛的反应，从而实现高效的反应和化学合成。这一研究成果使许多依赖催化的行业受益，使国民经济和社会受益。将研究成果整合到一门面向本科生和研究生的新课程中，将材料制造、反应工程和工业实践联系起来。向K-12和社区大学学生推广工艺技术是教育活动的一个方面。这项工作背后的科学概念是在通过加热区的气溶胶液滴的有限体积中合成陶瓷材料的化学方面。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内部结构导向有机模板的积累，导致模板的关闭并为二氧化硅的向内进展提供屏障，从而导致在煅烧时含有空心陶瓷的金属氧化物。该项目的重点是理解和进一步发展这一想法，并在空心颗粒中包含催化活性位点，如沸石。该项目研究了控制这些材料性能的方法，包括壳厚度和介孔率，以产生轻质陶瓷。它们在两个主要应用中的有效性，(a)氯化环境污染物的还原性脱氯和(b)非氧化甲烷偶联反应在环境修复和催化中的应用。该奖项反映了美国国家科学基金会的法定使命，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。

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.