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.
