This GOALI project addresses several needs in the area of diffusion in nanoporous materials, focusing particularly on zeolites as one important example. Nanoporous materials are widely used in catalysis, adsorption separations, and ion exchange. They also hold promise in new applications such as membranes, energy storage, and radioactive waste containment. In these applications, rates of mass transport can play a crucial role. Experimental studies and molecular modeling will be used to attain the following objectives:
o Develop a Hydrocarbon Trap for Cold-Start Automotive Exhaust Treatment. The Northwestern group has recently demonstrated a novel method for trapping molecules inside of zeolites by exploiting one-dimensional pores that exhibit single-file diffusion. Further experimental work is proposed to advance this concept for treating an important environmental problem. If time permits, molecular modeling will be applied to better understand whether particular systems exhibit single-file diffusion and the desired trapping.
o Create a Data Set of Multicomponent Diffusivities in Zeolites. Pulsed field gradient (PFG) NMR measurements will be used to obtain self-diffusion coefficients for a variety of multicomponent systems in zeolites. The lack of such data is holding back validation of theoretical models for multicomponent diffusion in zeolites. The data will be used to test theories for predicting multicomponent diffusivities from single-component values.
Broader Impact: This project will contribute to graduate education of 1 PhD student. Having both simulation and experiment in the same research group will enhance the research training. To go beyond traditional faculty mentoring, the student will also work closely with the industrial collaborator. This arrangement allows significant interaction with industry and industrial input to the research direction. In addition, graduate students can see how industrial research is done. Undergraduates will also be involved in smaller research projects, drawing particularly from summer research programs at Northwestern that make a special effort to recruit minority students.
The societal impact of trapping in one-dimensional zeolites is potentially very large if a hydrocarbon trap for vehicles can be developed. This could substantially reduce automotive hydrocarbon emissions and contribute to improved air quality. The project also demonstrates how fundamental science (single-file diffusion in this case) can help satisfy industrial and society needs in unexpected ways. Better understanding of multicomponent diffusion in zeolites could impact zeolite catalysis and adsorption separations, and particularly the development of zeolite membranes. These membranes promise energy-efficient separations processes and potentially highly selective membrane reactors.
