The research seeks to investigate scientific aspects of nanocatalytic combustion that are necessary for creating palm-size electric generators. Such portable power devices could be recharged quickly and fueled with high-energy-density liquid fuels (e.g., methanol: 22 MJ/kg, ethanol: 25 MJ/kg) compared to batteries (~0.5 MJ/kg), potentially valuable for many applications. One key is to use catalytic combustion, and the high reactivity of nano-sized catalytic metal particles could reduce the amount of catalyst needed, reduce the required operating temperatures, reduce heat loss, and increase overall system efficiency. In light of all of their advantages, too little is however known about the specifics that control the increased reactivity observed using nano-sized catalytic particles.
To improve fundamental understanding of the reactivity of nano-sized catalytic particles and enable their use in commercial technology, proposed study would involve an experimental investigation of catalytic combustion utilizing nano-sized particles in a flow reactor. The PIs have conducted preliminary experiments to demonstrate low light-off temperatures and low-temperature oxidation of methanol in a quartz-tube reactor, and they now propose to study the effects of catalyst particle size, catalyst mass loading, and catalyst deactivation systematically. Proposed experiments will characterize the combustion process in the catalytic bed reactor from temperature measurements and the catalyst by ex-situ analysis using SEM and TEM. Additionally, design and characterization of a meso-scale reactor in a planar geometry is proposed, interfacing with a thermo-electric generator as a means of palm-size electric generator. Modeling will be carried out utilizing commercial computational-fluid-dynamics software coupled with the Surface CHEMKIN chemical-kinetics model.
In additional to the scientific and technological impact of this work, it provides a valuable opportunity to train students in the promising area of catalytic combustion. Special attention will be given to attracting students from under-represented groups who might not otherwise consider advanced education or combustion science through existing programs at Drexel. Current outreach programs at Drexel University work with Philadelphia and Delaware Middle and High School teachers (MSP, RET) and will be enhanced with exercises in combustion, catalysis, nanotechnology and energy issues. By introducing these issues to a broad group of largely under-represented minority students, it will hopefully help them to further their interest in STEM fields.
This project explored nano-sized platinum particles for catalytic combustion of methanol-air mixtures. Our work demonstrated that these platinum nanoparticles can ignite a methanol-air mixture at room temperature without any external energy source. This phenomenon is unique to nanoparticles of platinum since bulk platinum does not demonstrate such high reactivity. This work also demonstrate the catalytic activity of the nanoparticles can be controlled by designing a microcombustor with specific amount of catalyst material and altering the flow rate of fuel-oxidizer mixture. We additionally showed that the reactivity of the nanoparticles is size-dependent in the sub-micron sizes. Furthermore, by careful design and deposition of catalyst a repeatable ignition and high methanol-air conversion rates can be achieved. These are important steps towards its future application. We also explored alternative fuels such as ethanol to demonstrate comparable trends. Such cyclic catalytic combustion can be useful in microcombustion devices such as those that integrate thermoelectrics. These integrated devices are promising future portable power sources with superior energy densities when compared to traditional batteries. Further work is being conducted to apply the outcomes of this work to develop portable power sources for use in commercial applications. Beyond the technical and research outcomes of this work, the PI and the collaborators gained crucial expertise in materials fabrication and characterization along with the eventual application of these materials. This work has inspired future explorations and collaborations in related technologies. Both graduate and undergraduate students participated in this work and gain valuable research experience as a result. Students acquired highly technical skills related to materials characterization and instrumentation. This work was also used to demonstrate the benefits of nanomaterials in a number of courses within engineering.
